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Recovery of steam-distilled extractives from Douglas fir veneer drying. Jeffrey, David Sinclair 1960

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RECOVERY OF STEAM-DISTILLED EXTRACTIVES PROM DOUGLAS FIR VENEER DRYING by DAVID SINCLAIR JEFFREY B . S c . ( F o r e s t r y ) U n i v e r s i t y of Aberdeen S c o t l a n d , 1953 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY i n the F a c u l t y of FORESTRY We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , I960 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada. A b s t r a c t A p i l o t study was conducted on the exhaust vapour which i s e x p e l l e d through the r o o f - v e n t i l a t o r s t a c k s of a Moore c r o s s c i r c u l a t i o n veneer d r y e r , i n order t o determine whether or not any by-products of commercial importance could be recovered from Douglas f i r veneer w h i l e i t i s undergoing normal d r y i n g o p e r a t i o n s p r i o r t o the manufacture of plywood, Separate s t u d i e s were made on the heartwood and sapwood veneer of t h i s s p e c i e s . Some s t e a m - d i s t i l l e d v o l a t i l e o i l was recovered from the st a c k gases, but because of the s m a l l amount which was c o l l e c t e d , t h i s m a t e r i a l was considered to be of no commercial v a l u e . Recommendations have been made f o r f u t u r e work i n t h i s f i e l d . i i CONTENTS Page Introduction 1 Review of L i t e r a t u r e 4 Wood composition 4 Naval stores industry 5 General 5 Processes 7 ( 1 ) Destructive d i s t i l l a t i o n 7 (2) Non-destructive d i s t i l l a t i o n 8 Some t h e o r e t i c a l aspects.of steam decomposition of wood 9 Steam d i s t i l l a t i o n 9 Steam and solvent e x t r a c t i o n . . . . . . . . 10 Steam d i s t i l l a t i o n v a r i a b l e s and t h e i r e f f e c t (upon the products obtained) 11 Chemical treatment p r i o r to f r a c t i o n a l d i s t i l l a t i o n 12 Hot a i r process 13 . Species c h a r a c t e r i s t i c s . . 13 Past h i s t o r y using Douglas f i r 17 Marketing 18 Turpentine 19 Summary of s a l i e n t points '. 21 Veneer Drying Equipment and Conditions of Drying.... 23 i i i Page C o l l e c t i o n of the Dryer Vapour 27 Sampling procedure 27 Method of c o l l e c t i o n 28 Q u a n t i t a t i v e A n a l y s i s of the Condensate 33 D e s c r i p t i o n of the condensate 33 Assumptions of the a n a l y s i s 33 A n a l y t i c a l procedure 34 C a l c u l a t i o n of R e s u l t s 41 T o t a l condensate ( t h e o r e t i c a l l o s s of moisture i n d r y i n g ) 41 T o t a l v o l a t i l e o i l f r a c t i o n of the condensate.. 45 Summary, of c a l c u l a t i o n s 52 D i s c u s s i o n of R e s u l t s 53 Assumptions i n the t h e o r e t i c a l c a l c u l a t i o n s . . . . 53 T o t a l condensate 55 V o l a t i l e o i l 58 Summary 63 B i b l i o g r a p h y 65 Appendix A P l a n of a cro s s c i r c u l a t i o n veneer d r y e r . . . . 68 B Dryer temperature study 69 C Stack a i r v e l o c i t y 70 D B o i l i n g p o i n t range d e t e r m i n a t i o n 71 E Q u a n t i t a t i v e a n a l y s i s r e s u l t s f o r t o t a l condensate 72 i v TABLES TABLE PAGE 1. R e l a t i o n s h i p between t h e o r e t i c a l and experimental y i e l d s of t o t a l condensate 43 2. V o l a t i l e o i l recovered from the d r y e r s 4-7 3 . R e l a t i o n s h i p between t h e o r e t i c a l and experimental y i e l d s of v o l a t i l e o i l 51 4. Summarized comparison between t h e o r e t i c a l and a c t u a l y i e l d s 53 V FIGURES FIGURE PAGE 1. Steam d i s t i l l a t i o n of wood 8 2 . Condensing apparatus i n p o s i t i o n 2 9 3 . Condensing apparatus i n p o s i t i o n 2 9 4 . Condenser 3 0 5 . Condenser (with l i d removed) 3 0 6 . Condenser (showing c o i l s ) 3 0 7 . Analysis of the condensate 34-v i Acknowledgement The author wishes to express h i s g r a t i t u d e to Dr. R.W. Wellwood and Mr. R.W. Kennedy of the F a c u l t y of F o r e s t r y at the U n i v e r s i t y of B r i t i s h Columbia, f o r t h e i r d i r e c t i o n and c o n s t r u c t i v e c r i t i c i s m . He i s g r e a t l y indebted to Mr. J . Burch of MacMillan, B l o e d e l , and P o w e l l R i v e r L i m i t e d , f o r h i s "guid'ahce and i n v a l u a b l e c o o p e r a t i o n i n a l l p r a c t i c a l -aspects of the p r o j e c t . The author would a l s o l i k e t o thank Mr. G. Barton of the F o r e s t Products L a b o r a t o r i e s of Canada (Vancouver), f o r i n s t r u c t i o n on the q u a n t i t a t i v e a n a l y s i s work, and Mr. A.W. N e s b i t t of The Moore Dry K i l n Company L i m i t e d , f o r p r o v i d i n g t e c h n i c a l i n f o r m a t i o n about the veneer d r y e r . RECOVERY OP STEAM-DISTILLED EXTRACTIVES PROM DOUGLAS FIR VENEER DRYING I n t r o d u c t i o n Research i s the key to i n d u s t r i a l p r o g r e s s . The main o b j e c t i v e of i n d u s t r i a l r e s e a r c h i s to apply s c i e n t i f i c knowledge i n order to creat e new prod u c t s , enhance the value of o l d pro d u c t s , and i n c r e a s e the e f f i c i e n c y of p r o d u c t i o n , by d e s i g n i n g new machines, reducing and u t i l i z i n g waste, and upgrading the average q u a l i t y of the product. In 1958 the Vancouver Plywood D i v i s i o n of MacMillan, B l o e d e l and Powell R i v e r L t d . , l o c a t e d i n Vancouver, B r i t i s h Columbia, surveyed the p o s s i b i l i t y of o b t a i n i n g commercial by-products from vapour d r i v e n o f f i n veneer d r y i n g . T h i s d r y i n g was done by means of mechanical.veneer d r y e r s i n t o which the veneer was f e d on r o l l s . As i t moved through these d r y i n g ovens, the veneer was subj e c t e d to temperatures ranging from 174 deg. C to 204 deg. G which r e s u l t e d i n the moisture content of the wood being lowered to a l e v e l of between 2 per cent and 5 per cent. Moisture from the wood was d r i v e n o f f i n gaseous form and t h i s vapour was e i t h e r exhausted through roof v e n t i l a t o r stacks or was condensed on the inside of the dryer w a l l s . Because of the high temperatures involved, i t was f e l t that these exhaust gases might contain some products which would be of commercial importance and which would be capable of being recovered by a simple i n d u s t r i a l d i s t i l l a t i o n procedure. The large volume of vapour which was driven o f f each day from a veneer dryer added optimism to. t h i s b e l i e f and l e d to a recommendation, at that time, that t h i s question merited further and more c a r e f u l i n v e s t i g a t i o n to determine whether or not such a development would be commercially p r o f i t a b l e . An a d d i t i o n a l i n v e s t i g a t i o n was c a r r i e d out by the author. The objectives were as follows: (1) To determine the quantity of vapour which i s exhausted through the roof v e n t i l a t o r stacks. (2) To determine the proportion of chemical extractives i n t h i s vapour. ( 3 ) To investigate the composition of t h i s e x t r active material i n an e f f o r t to determine the major components present and the r e l a t i v e quantities of these components. ( 4 ) To make a commercial evaluation of the recovery process on the basis of these r e s u l t s . Douglas f i r (Pseudotsuga menziesii (Mirb.) Franco) has f o r many years been the leading species used by the 3 softwood plywood i n d u s t r y i n the P a c i f i c northwest. In order to r e l a t e t h i s work as much as p o s s i b l e to the normal manufacturing c o n d i t i o n s of the softwood plywood i n d u s t r y i n B r i t i s h Columbia, i t was decided t h a t o n l y Douglas f i r veneer would be i n v e s t i g a t e d . No sharp l i n e of demarcation e x i s t s between fundamental and a p p l i e d r e s e a r c h i n f o r e s t p r o ducts, o r between a p p l i e d r e s e a r c h and wood products development. T h i s p r o j e c t was not intended to be a fundamental r e s e a r c h study i n t o the elementary chemical composition of exhaust vapours. I t was a u t i l i z a t i o n problem which sought a method of re d u c i n g p h y s i c a l wastage by r e t r i e v i n g m a t e r i a l which i s at present r e j e c t e d and u s i n g t h i s m a t e r i a l f o r the manufacture of a v a r i e t y of commercial products. In o t h e r words, i t was an attempt towards a h i g h e r and more e f f e c t i v e u t i l i z a t i o n of the wood m a t e r i a l which i s p r e s e n t l y used f o r the manufacture of plywood, by determining whether or not chemical e x t r a c t i v e s , d e r i v a t i v e s or products of commercial value could be p r o f i t a b l y recovered from t h i s m a t e r i a l without a d v e r s e l y e f f e c t i n g normal veneer d r y i n g o p e r a t i o n s . Some of the many b e n e f i t s to be gained from the recovery of chemicals by t h i s means are: (a) There would be no c o m p e t i t i o n f o r wood raw m a t e r i a l , or f o r markets, between plywood and the chemical by-products. 4 (b) A greater economic return would be r e a l i s e d f o r the same wood resources. This higher conversion rate f o r avail a b l e wood raw material, along with a d d i t i o n a l revenue from the sale of the by-products, would help to reduce the expense of veneer drying f o r the production of plywood. (c) The recovery process would not require a large investment i n a d d i t i o n a l equipment, nor would a d d i t i o n a l supplies of f u e l f o r heating the veneer dryers be needed. (d) Greater product d i v e r s i f i c a t i o n would lend s t a b i l i t y to the plywood industry and make i t l e s s vulnerable to market f l u c t u a t i o n i h p r i c e or demand. (e) The future p o t e n t i a l of chemical products derived from wood i s very great and these products may eventually become as important and valuable as the primary wood products of today. Review of L i t e r a t u r e Wood composition Wood as i t occurs i n nature i s made up of c e l l u l o s e , hemicellulose, l i g n i n and extraneous components. The extraneous components are not an i n t e g r a l part of the c e l l w all and can 5 u s u a l l y be removed by n e u t r a l s o l v e n t s such as e t h e r , a l c o h o l , water, e t c . , without a f f e c t i n g e i t h e r the chemical composition of the wood substance, or the p h y s i c a l s t r u c t u r e of the c e l l w a l l . They a l s o have a non-uniform d i s t r i b u t i o n throughout the bole of the t r e e . Extraneous components can be .subdivided i n t o two groups. The f i r s t group, c a l l e d " e x t r a c t i v e s " , i s composed of chemicals which can be removed e a s i l y by n e u t r a l s o l v e n t s . Among these e x t r a c t i v e s are substances such as r e s i n a c i d s , c o l o u r i n g matter, waxes, e t c . . The second group c o n s i s t s of miscellaneous components. These are substances i n the wood which cannot be removed e a s i l y by s o l v e n t s but which n e v e r t h e l e s s are q u i t e d i s t i n c t from the c e l l w a l l , f o r example, s t a r c h g r a i n s , s i l i c a , and c a l c i u m o x a l a t e c r y s t a l s . E x t r a c t i v e s are g e n e r a l l y found i n the c e l l c a v i t i e s , but they may a l s o be present i n very f i n e c a p i l l a r i e s of the c e l l w a l l thereby making t h e i r complete removal q u i t e i m p o s s i b l e . The heartwood of softwoods has a h i g h content of water, eth e r , and a l k a l i - s o l u b l e e x t r a c t i v e s ( 2 7 ) . Naval s t o r e s i n d u s t r y General Naval s t o r e s can be d e f i n e d as "Chemically r e a c t i v e o i l s , - r e s i n s , t a r s and p i t c h e s d e r i v e d from the o l e o r e s i n contained i n , exuded by, or e x t r a c t e d from t r e e s , c h i e f l y of the pine s p e c i e s (Genus P i n u s ) , or from the wood of such t r e e s " ( 2 ) . 6 O l e o r e s i n i s the non-aqueous s e c r e t i o n of r e s i n a c i d s d i s s o l v e d i n a terpene hydrocarbon o i l which i s ; (1) Produced or exuded from the i n t e r c e l l u l a r r e s i n ducts of a l i v i n g t r e e . ( 2) Accumulated, t o g e t h e r w i t h o x i d a t i o n p r o d u c t s , i n the dead wood of weathered limbs and stumps ( 2 ) . The outmoded but unshed name of the n a v a l s t o r e s i n d u s t r y was d e r i v e d from the former uses of i t s products, namely, wood t a r and p i t c h , f o r c a u l k i n g wooden ships and f o r p r e s e r v a t i v e treatment of t h e i r r i g g i n g . The c h i e f products of the n a v a l s t o r e s i n d u s t r y are now t u r p e n t i n e and r o s i n . Turpentine i s a v o l a t i l e o i l which c o n s i s t s of a number of terpene hydro-carbons and i s obtained by d i s t i l l i n g the o l e o r e s i n exuded by, or contained i n , the wood of c e r t a i n s p e c i e s of pine t r e e s ( 2 ) . Rosin i s a s p e c i f i c k i n d of n a t u r a l r e s i n obtained as a v i t r e o u s , water i n s o l u b l e m a t e r i a l from pine o l e o r e s i n by the removal of the v o l a t i l e o i l s ( 2 ) . Naval s t o r e s are c l a s s i f i e d a c c o r d i n g to the method of o b t a i n i n g the re s i n o u s raw m a t e r i a l . "Gum" n a v a l s t o r e s c o n s i s t , of products which are d e r i v e d from the s e c r e t i o n or exudate of the l i v i n g t r e e , t h i s exudate having been c o l l e c t e d by the process known as t u r p e n t i n i n g . "Wood" n a v a l s t o r e s on the other hand, are products which have been manufactured from the wood substance a f t e r the t r e e has been cut. This wood u s u a l l y c o n s i s t s of f o r e s t and i n d u s t r i a l r e s i d u e s which have been s p e c i a l l y s e l e c t e d because of t h e i r h i g h r e s i n content. 7 1; . T Processes Wood n a v a l s t o r e s can be produced i n two ways: (1) d e s t r u c t i v e d i s t i l l a t i o n . T h i s c o n s i s t s of h e a t i n g the wood i n a c l o s e d r e t o r t equipped w i t h an opening l e a d i n g to a condenser where the vapours escape, condense and are c o l l e c t e d . The wood i s d i s i n t e g r a t e d as a r e s u l t of t h i s heat treatment. A more recent development i n t h i s f i e l d has been the a l k a l i s o l v e n t process which i s the recovery of P.M.L. (pulp m i l l l i q u o r ) grade t u r p e n t i n e as a by-product from the spent cooking l i q u o r s of sulphate pulp m i l l s . T h i s i s used f o r terpene-based chemicals ( f o r example, s y n t h e t i c pine o i l ) and i t s p r o d u c t i o n has become a p r o f i t a b l e venture i n some areas of the U.S.A. where some companies have r e p o r t e d a net r e t u r n of 29.6 per cent on P.M.L. grade t u r p e n t i n e recovery ( 4 ) . A c t u a l areas i n which t h i s p r o f i t a b l e o p e r a t i o n i s being conducted were not r e p o r t e d , but i t most probably r e f e r s t o the southern pine r e g i o n of the U.S.A. Newmarch"1" r e p o r t e d t h a t the recovery of t u r p e n t i n e from k r a f t p u l p , c o n s i s t i n g of 50 per cent Douglas f i r mixed w i t h hemlock and cedar, would only be p r o f i t a b l e i f allowance were made f o r heat recovery from the hot water coming from the t u r p e n t i n e condensers. Y i e l d s were recorded of 0.9 U.S. g a l l o n s of t u r p e n t i n e and 2.1 U.S. g a l l o n s of water at 180 deg.G, 1 Newmarch, O.H., Recovery of Turpentine from Douglas  F i r K r a f t P u l p . Unpublished r e p o r t , M a c M i l l a n , B l o e d e l and Powell R i v e r L i m i t e d , Harmac D i v i s i o n , November 1959» 8 per ton of f i r pulp. I t was observed t h a t d i r e c t steaming g r e a t l y i n c r e a s e d the y i e l d of t u r p e n t i n e , but t h a t a heavy steam fl o w of up to 20,000 pounds per hour was r e q u i r e d f o r a s i g n i f i c a n t e f f e c t . A h i g h e r than normal r a t e of d i g e s t e r r e l i e f was a l s o necessary i n order t o get a y i e l d approaching t h a t r e p o r t e d by othe r s . Newmarch s t a t e d t h a t as more v o l a t i l were r e l e a s e d e a r l y i n the steaming, an improved product, w i t h a lower b o i l i n g p o i n t range, would probably be obtained i f l a t e r r e l i e f gases were n e g l e c t e d . (2) Non-destructive d i s t i l l a t i o n . I n t h i s p rocess, the wood i s not destroyed but i s t r e a t e d w i t h a medium which e x t r a c t s some of the r e s i n o u s products from the wood, producing a chemical composition change, but not a marked p h y s i c a l chang In normal commercial p r a c t i c e the wood i s ground or cut i n t o p a r t i c l e s p r i o r to d i s t i l l a t i o n . A common medium used f o r t h i s work i s steam, which removes v a r i o u s products from wood, as i l l u s t r a t e d i n Figu r e 1 Softwood i n r e t o r t + steam [Residual wood"! |Vapours" Condenser i S e p a r a t i o n i n s e t t l i n g v a t s Crude o i l s Water F r a c t i o n a t i o n i ' Wood t u r p s . & steam Pine o i l F i g . 1. Steam d i s t i l l a t i o n of wood ( 7 ) 9 Pine o i l i s a c o l o u r l e s s to amber coloured v o l a t i l e o i l w i t h c h a r a c t e r i s t i c pinaceous odour, c o n s i s t i n g p r i n c i p a l l y of t e r t i a r y and secondary terpene a l c o h o l s , w i t h v a r i a b l e q u a n t i t i e s of terpene hydrocarbons, e t h e r s , phenols, e t c . , the amount and c h a r a c t e r : o f which depend on the source and method of manufacture ( 2 ) . Some t h e o r e t i c a l aspects of steam decomposition of wood When two non-miscible (mutually i n s o l u b l e ) l i q u i d s , such as o i l and water, are heated w h i l e kept i n e q u i l i b r i u m (by s t i r r i n g ) , the mixture w i l l b egin to b o i l when the sum of the vapour pressures of the c o n s t i t u e n t s equals atmospheric pr e s s u r e . The mixture w i l l t h e r e f o r e b o i l at a temperature which w i l l be lower than the b o i l i n g p o i n t of e i t h e r o i l or water. When c o n s i d e r i n g the o i l and water contained i n wood, however, t h i s concept becomes complicated because the wood substance i t s e l f prevents f r e e contact between steam and the o i l s to be d i s t i l l e d , so t h a t there i s not a true e q u i l i b r i u m e x i s t i n g w i t h i n the wood. Steam d i s t i l l a t i o n Hawley ( 17) r e p o r t e d t h a t i n the presence of steam, some v o l a t i l e o i l s were d i s t i l l e d below 100 deg. C, and i f enough water was i n the wood to f u r n i s h steam, these v o l a t i l e s might d i s t i l l completely at temperatures below 100 deg.C. I t was noted f u r t h e r that most of the v o l a t i l e o i l s would d i s t i l l below the temperature (approximately 250 deg.C) at which wood 10 begins to decompose s t r o n g l y , but t h a t r o s i n a l s o decomposed below t h i s temperature, and some contamination of the t u r p e n t i n e by t h i s r o s i n might occur. Such contamination, however, was f e l t to be very s l i g h t below 200 deg.C. Hawley observed f u r t h e r t h a t not much water and t u r p e n t i n e d i s t i l l a t e was r e c e i v e d below 160 deg.C because a t r u e e q u i l i b r i u m d i d not e x i s t w i t h i n the wood, and not u n t i l the r e s i n became a t h i n f l u i d w i t h the heat, and began to f l o w i n the wood, d i d much d i s t i l l i n g take p l a c e . I t was s t a t e d t h a t i n s t e a d of g e t t i n g an i n i t i a l d i s t i l l a t i o n of t u r p e n t i n e and some pine o i l , f o l l o w e d by r o s i n , o f t e n a l l three would be d i s t i l l e d at the same time. I n steam d i s t i l l a t i o n , the condensate, i f allowed to s e t t l e , w i l l separate i n t o an upper o i l l a y e r and a lower aqueous l a y e r . The o i l l a y e r i s drawn o f f and f r a c t i o n a l l y d i s t i l l e d i n t o a lower b o i l i n g f r a c t i o n (temperature not exceeding 180 deg.C) c o n s i s t i n g of steam and t u r p e n t i n e , and a higher b o i l i n g f r a c t i o n of pine o i l . Steam and s o l v e n t e x t r a c t i o n The steam and s o l v e n t process c o n s i s t s of normal steam d i s t i l l a t i o n , f o l l o w e d by treatment of the steam-extracted wood w i t h a s o l v e n t , such as ammonium hydroxide, to remove the remainder of the r o s i n i n the wood. In d e s c r i b i n g t h i s process, Hawley and Palmer (18) r e p o r t e d t h a t the steaming produced a very good q u a l i t y of 11 "crude t u r p e n t i n e " c o n s i s t i n g e s s e n t i a l l y of t u r p e n t i n e and pine o i l , "but because t h i s was the o n l y product obta i n e d , and because the y i e l d of t h i s product was g e n e r a l l y lower than t h a t of "crude t u r p e n t i n e " from other processes, steam and s o l v e n t process p l a n t s were o n l y s u c c e s s f u l when e s p e c i a l l y f a v o u r a b l e c o n d i t i o n s e x i s t e d . Palmer's (24) account of t h i s process s t a t e d t h a t the b u l k of the v o l a t i l e o i l present i n wood was d r i v e n o f f by the steam. This primary d i s t i l l a t e c o n s i s t e d e s s e n t i a l l y of t u r p e n t i n e and pine o i l i n v a r y i n g p r o p o r t i o n s depending upon the c o n d i t i o n s of steaming. Some terpene hydrocarbons ( f o r example, limoneney dipentene, e t c . ) , w i t h a b o i l i n g range between t h a t of pinene (the p r i n c i p a l c o n s t i t u e n t of t u r p e n t i n e ) and pine o i l , might a l s o be present but t h i s f r a c t i o n c ould be removed i n f r a c t i o n a l d i s t i l l a t i o n . I n modern p r a c t i c e f o r the p r o d u c t i o n of wood naval s t o r e s , steam d i s t i l l a t i o n i s e l i m i n a t e d , and a l l e x t r a c t i o n s of the wood raw m a t e r i a l i s done by s o l v e n t s , such as benzene and naphtha. Steam d i s t i l l a t i o n v a r i a b l e s and t h e i r e f f e c t (upon the products obtained) Palmer (24) s t a t e d t h a t the t o t a l y i e l d of crude o i l , the composition of t h i s o i l and the amount of steam r e q u i r e d to remove the o i l , would be a f f e c t e d by v a r i a b l e s such as: 12 (1) Wood c h a r a c t e r i s t i c s ( f o r example, s p e c i e s , r e s i n content, dimension of the wood m a t e r i a l ) (2) Steam pressure (3) Speed of d i s t i l l a t i o n (4-) The end p o i n t at which d i s t i l l a t i o n i s stopped. Hawley and Palmer (18) e s t a b l i s h e d t h a t the y i e l d of crude o i l was improved by i n c r e a s i n g steam pressure and decreasing the speed of d i s t i l l a t i o n as w e l l as by u s i n g h i g h l y r e s i n o u s , small s i z e d wood raw m a t e r i a l . This p o i n t p was r e a f f i r m e d by Newmarch i n h i s recent i n v e s t i g a t i o n i n t o the recovery of t u r p e n t i n e from k r a f t pulp l i q u o r . Hawley (16) found t h a t the p r o p o r t i o n of dipentene i n r e f i n e d t u r p e n t i n e i n c r e a s e d i n d i r e c t r e l a t i o n to the maximum temperature of p r o d u c t i o n . Hawley and Palmer (18) observed t h a t i n c r e a s e i n steam pressure had no e f f e c t on the p r o p o r t i o n of pine o i l contained i n the d i s t i l l a t e but t h a t i t d i d i n c r e a s e the amount of dipentene present. The l i g h t o i l ( b o i l i n g p o i n t below 175 deg. C) f r a c t i o n had a high e r s p e c i f i c g r a v i t y which i n d i c a t e d t h a t substances of low b o i l i n g p o i n t and high s p e c i f i c g r a v i t y were produced at higher steam p r e s s u r e s . Chemical treatment p r i o r to f r a c t i o n a l d i s t i l l a t i o n Hawley (16) d e c l a r e d t h a t a chemical treatment was 2 0p_. c i t . 13 r e q u i r e d before f r a c t i o n a l d i s t i l l a t i o n of the crude wood o i l would produce a good grade of r e f i n e d t u r p e n t i n e because i t would remove the l i g h t o i l s which had b o i l i n g p o i n t s lower than t h a t of t u r p e n t i n e , thereby improving the c o l o u r and odour of the r e f i n e d t u r p e n t i n e . Palmer (24) r e f e r r e d to a chemical d i s t i l l a t i o n w i t h c a u s t i c soda p r i o r to f r a c t i o n a l d i s t i l l a t i o n by which any wood a c i d s which might be present would be n e u t r a l i s e d , and contaminous m a t e r i a l , such as l i g h t o i l s , which a d v e r s e l y e f f e c t grade, c o l o u r , and odour would be polymerised. The American S o c i e t y f o r T e s t i n g M a t e r i a l s ( 3 ) , however, suggested t h a t chemical treatment p r i o r t o f r a c t i o n a l d i s t i l l a t i o n was not necessary i n cases where d i s t i l l a t i o n temperatures would be kept below 200 deg.C. Hot a i r process I t i s of i n t e r e s t to note t h a t a n o n - d e s t r u c t i v e d i s t i l l a t i o n process u s i n g hot a i r as a medium f o r the removal of v o l a t i l e o i l s , along w i t h a s m a l l amount of low grade r o s i n , has been attempted, but w i t h no apparent commercial success (13). Species c h a r a c t e r i s t i c s Although hardwoods, such as beech (Genus Fagus) and oak (Genus Quercus), are used t o produce wood n a v a l s t o r e s , t h i s i n d u s t r y mainly r e l i e s upon softwoods f o r the manufacture of i t s products. Each s p e c i e s of wood y i e l d s a crude o i l which i s more or l e s s d i f f e r e n t from those of the o t h e r s . Only a few of the many s p e c i e s of c o n i f e r s y i e l d s a t i s f a c t o r y 14 q u a n t i t i e s of t u r p e n t i n e and wood o i l . The commercial softwood species c o n s i s t mainly of the pines although other s p e c i e s , among which i s Douglas f i r , have been used w i t h a c e r t a i n amount of success. In the Uni t e s S t a t e s , which produces about 53 per cent of the world's n a v a l s t o r e s requirements (4-), the p r i n c i p a l s p e c i e s used are the l o n g l e a f pine (Pinus p a l u s t r i s M i l l . ) and the s l a s h pine (P. e l l i o t t i i Engelm.). France, on the other hand, mainly uses the maritime pine (P. p i n a s t e r A i t o n . ) and the aleppo pine (P. h a l e p e n s i s M i l l e r . ) to produce 20 per cent of the world's supply ( 4 ) . The amount of r e s i n o u s e x t r a c t i v e s i n common Canadian woods i s r e l a t i v e l y low. Harkom and C o l l e a r y ( 1 3 ) p o i n t e d out t h a t apart from the southern pines (P. p a l u s t r i s M i l l . , P. r i g i d a M i l l . , P. e l l i o t t i i Engelm., e t c . ) , o n l y three other s p e c i e s , Norway pine (P. r e s i n o s a A i t o n . ) , western y e l l o w pine (P. ponderosa Dougl.), and Douglas f i r had been suggested as o f f e r i n g p o s s i b i l i t i e s as a source of raw m a t e r i a l . These were a l s o the o n l y Canadian species r e g a r d i n g which p r o d u c t i o n y i e l d s from commercial p r a c t i c e or i n d u s t r i a l r e s e a r c h were a v a i l a b l e . One of the measures of the r e s i n o u s content of a wood i s i t s ether s o l u b i l i t y . T h i s i s the weight of d r i e d e t h e r -e x t r a c t e d r e s i d u e c a l c u l a t e d as a percentage of the weight of the oven-dry ( 105 deg. C) i n i t i a l wood sample. While ether 15 s o l u b i l i t y does not i n c l u d e a l l e x t r a c t i v e s i n wood, i t p r o v i d e s some i n d i c a t i o n of the amount of e x t r a c t i v e s p r e s e n t , e x c l u s i v e of most w a t e r - s o l u b l e m a t e r i a l s ( 1 2 ) . Hawley (17) determined the ether s o l u b i l i t y of s e v e r a l softwood s p e c i e s as shown i n the f o l l o w i n g t a b l e : E t h e r s o l u b i l i t y of some softwood s p e c i e s Species Per cent O.D. Weight Western y e l l o w pine (Pinus ponderosa) 8 .52 Longleaf pine (Pinus p a l u s t r i s ) 6 . 3 2 Western white pine (Pinus monticola) 4.26 White spruce ( P i c e a g l a u c a X " 1.36 Douglas f i r (Pseudotsuga m e n z i e s i i ) 1 . 0 2 I t i s not known what type of wood (sapwood, heartwood, stumpwood, e t c . ) was used f o r these d e t e r m i n a t i o n s , or the moisture content of the wood. Greaves and Schwartz (12) found the ether s o l u b i l i t y of Douglas f i r heartwood t o be 1.14 per cent. I t can be seen from these f i g u r e s t h a t the s p e c i e s of g r e a t e s t commercial use i n the U n i t e d S t a t e s n a v a l s t o r e s i n d u s t r y , namely l o n g l e a f p i n e , has a c o n s i d e r a b l y h i g h e r e t h e r s o l u b i l i t y f a c t o r than Douglas f i r . R e s i n i s not evenly d i s t r i b u t e d i n the t r e e . Sapwood co n t a i n s very l i t t l e of i t , w hile heartwood of the stump and b u t t l o g may be v e r y r e s i n o u s . Heartwood of the main bole of the t r e e i s i n t e r m e d i a t e i n i t s r e s i n content. I n l o n g l e a f p i n e , sapwood may c o n t a i n about 2 per cent r e s i n , the average heartwood 7 to 10 per cent, heartwood of the b u t t l o g 15 per cent, and the heartwood of the stump 25 per cent or more ( 1 3 ) . 16 I t i s important to note t h a t the wood which i s a c t u a l l y used as a raw m a t e r i a l f o r the commercial p r o d u c t i o n of n a v a l s t o r e s i s s p e c i a l l y s e l e c t e d f o r i t s e x t r a h i g h r e s i n content. The wood raw m a t e r i a l which i s most p r e f e r r e d i s c a l l e d "lightwood", i n which the gum i n the wood c e l l has hardened and become sealed i n t o the c e l l and wood s t r u c t u r e . Longleaf pine "lightwood" i s a v a i l a b l e i n commercial q u a n t i t i e s i n c e r t a i n p a r t s of the southern s t a t e s r e g i o n of the Uni t e d S t a t e s , where i t i s re p o r t e d to have an average r e s i n content of 20 to 25 per cent ( 1 3 ) • Schorger (29) examined the composition of o l e o r e s i n which was e x t r a c t e d from the base of l i v i n g Douglas f i r t r e e s and h i s r e s u l t s were: Composition of o l e o r e s i n of Douglas f i r Source of o l e o r e s i n Vola-b i l e o i l s Colophony % Water and l o s s e s % p r o p o r t i o n % S p e c i f i c g r a v i t y Heartwood 30.40 0.862 68.82 0.78 Heartwood 28.64 0.863 69.77 1.59 Sapwood 22.70 0.863 Not given Not given The i n i t i a l moisture contents of n e i t h e r the heartwood nor the sapwood of these s t a n d i n g t r e e s were determined by Schorger. 17 Past h i s t o r y u s i n g Douglas f i r There appears to be no doubt t h a t c e r t a i n t r e e s c o n t a i n a h i g h e r r e s i n content than o t h e r s , but i t i s g e n e r a l l y conceded t h a t the average y i e l d from western c o n i f e r s i s low compared t o t h a t of t r e e s i n the southern pine r e g i o n of the Uni t e d S t a t e s . Frequent ref e r e n c e has been made to Douglas f i r as a probable source of both wood and gum t u r p e n t i n e , and r o s i n . Between 1910 and 1914, a few companies attempted to e x t r a c t t u r p e n t i n e and r o s i n from Douglas f i r by both steam d i s t i l l a t i o n and d e s t r u c t i v e d i s t i l l a t i o n , but these p l a n t s were small and app a r e n t l y d i d not meet w i t h s u f f i c i e n t l y pronounced success to induce others to i n v e s t i n s i m i l a r e n t e r p r i s e s . One such company was formed i n Vancouver, B r i t i s h Columbia, around 1910. T h i s p l a n t employed a method of d e s t r u c t i v e d i s t i l l a t i o n known as the Snyder e l e c t r i c a l process f o r the removal of t u r p e n t i n e from Douglas f i r m i l l r e s i d u e (9 , 1 3 ) . The e f f e c t of the 1914 to 1918 war i n c u r t a i l i n g p r o d u c t i o n of n a v a l s t o r e s i n the U n i t e d S t a t e s , and b r i n g i n g an i n c r e a s e i n p r i c e s f o r these p r o d u c t s , r e v i v e d an i n t e r e s t i n Douglas f i r . A t t e n t i o n became ce n t r e d more on gum products r a t h e r than wood products, and a few companies were e s t a b l i s h e d i n the P a c i f i c northwest to manufacture the former. The Douglas F i r Turpentine Co. of Vancouver, B r i t i s h Columbia, pioneered the p r o d u c t i o n on a commercial s c a l e of 18 gum t u r p e n t i n e and r o s i n from Douglas f i r i n B r i t i s h Columbia. T h i s company secured sap r i g h t s to l a r g e b l o c k s of p r i v a t e l y -owned f o r e s t on Cortez I s l a n d , which i s s i t u a t e d due east of Campbell R i v e r on Vancouver I s l a n d , and began t u r p e n t i n i n g operations i n a s m a l l way ( 9 ) . This e n t e r p r i s e , however, e v e n t u a l l y f a i l e d . No work was r e p o r t e d to have been done u s i n g e i t h e r Douglas f i r heartwood or sapwood i n the bole of the t r e e as a wood raw m a t e r i a l . The U n i v e r s i t y of Washington En g i n e e r i n g Experimental S t a t i o n ( 1 3 ) , however, r e p o r t e d a c e r t a i n amount of success from steam and s o l v e n t e x t r a c t i o n of o r d i n a r y stumpwood of t h i s s p e c i e s . The r e s u l t s of t h i s d i s t i l l a t i o n work were: T o t a l o i l f r a c t i o n 0.9 U.S. g a l l o n s from 3800 l b . wood Turpentine 0.6 11 " 11 . 11 " " Pine o i l 0.3 " " " " " 11 Rosin 75 pounds from 3800 l b . wood Marketing No wood or gum n a v a l s t o r e s have been produced i n Canada s u c c e s s f u l l y on a commercial s c a l e . The main reasons f o r t h i s are f i r s t l y , because the average r e s i n content of the t r e e s grown i n t h i s country i s c o n s i d e r a b l y lower than t h a t of the southern p i n e s ; secondly, the wood raw m a t e r i a l would have to be s p e c i a l l y s e l e c t e d to g i v e commercially p r o f i t a b l e y i e l d s , and f i n a l l y , because the cost of o b t a i n i n g the raw m a t e r i a l 19 would be exc e s s i v e ( 3 0 ) . H a r r i s ( 1 5 ) s t a t e d t h a t any attempt to produce n a v a l s t o r e s from the B r i t i s h Columbia f o r e s t s would be doomed to f a i l u r e because of severe c o m p e t i t i o n from the southern pine r e g i o n , but tha t the p o s s i b i l i t y of o b t a i n i n g these n a v a l s t o r e s as by-products of another wood products i n d u s t r y would be a ve r y d i f f e r e n t s t o r y . I t was p o i n t e d out t h a t a company producing n a v a l s t o r e s as a by-product would not be dependent upon the s a l e of these secondary products as a source of revenue. In a d d i t i o n to t h i s , these chemical by-products would have no d e t r i m e n t a l e f f e c t upon the market f o r the major product and t h e i r s a l e would f u r t h e r i n c r e a s e the revenue d e r i v e d from the o r i g i n a l wood raw m a t e r i a l . The n a v a l s t o r e s i n d u s t r y today i s s t i l l a m i l l i o n -d o l l a r b u s i n e s s , even though the market value of gum t u r p e n t i n e and r o s i n has been cut i n h a l f i n the p e r i o d from 1949 t o 1959 ( 4 ) . The i n c r e a s i n g need f o r both t u r p e n t i n e and r o s i n as chemical r a w i m a t e r i a l s has been met by s u p p l i e s of wood n a v a l s t o r e s from d i v e r s i f i e d sources. For example, P.M.L. grade t u r p e n t i n e d e r i v e d from spent sulphate pulp l i q u o r i s combined w i t h steam d i s t i l l e d t u r p e n t i n e i n the manufacture of 30 per cent of the world's s y n t h e t i c pine o i l p r o d u c t i o n ( 4 ) . Turpentine Crude o i l produced by steam d i s t i l l a t i o n i s almost e n t i r e l y f r e e from r o s i n s p i r i t s and r o s i n o i l owing to the f a c t t h a t r o s i n i s not decomposed by the steaming and remains 20 i n the wood a f t e r the t u r p e n t i n e has been d i s t i l l e d o f f . The normal products of d i s t i l l a t i o n are t u r p e n t i n e , which has a b o i l i n g p o i n t range of 150 deg. C t o 175-180 deg. C, and pine o i l , whose b o i l i n g p o i n t range i s 175-180 deg. C to 240-250 deg. C (16). The temperature of a mechanical veneer d r y e r seldom exceeds 205 deg. C, and u s u a l l y f l u c t u a t e s w i t h i n the range of 175 deg. C and 197 deg. C. Because of these h i g h temperatures, some crude wood o i l w i l l probably be steam d i s t i l l e d out of the veneer. I t i s t o be expected t h a t some of t h i s crude o i l w i l l be d r i v e n out of the d r y e r through the r o o f v e n t i l a t o r s t a c k s . When c o n s i d e r i n g the temperature range i n v o l v e d i n the d r y i n g o p e r a t i o n , there i s some j u s t i f i c a t i o n i n assuming t h a t the major product to be d e r i v e d from the crude wood o i l w i l l be t u r p e n t i n e . I t has been p r e d i c t e d by the chemical i n d u s t r y (25) t h a t 16 per cent of chemical s a l e s i n I960 w i l l be i n the form of new products. I t i s a l s o estimated t h a t due t o re s e a r c h work i n t h i s f i e l d , about 10,000 new chemical products are made a n n u a l l y , 400'of which are•of* commercial s i g n i f i c a n c e . Two use p a t t e r n s of t u r p e n t i n e are i l l u s t r a t e d i n . t h e t a b l e below. Because these examples are d e r i v e d from d i f f e r e n t sources, however, they are not d i r e c t l y comparable. 21 The uses of t u r p e n t i n e 1941 ( 1 0 ) 1959 ( 4 ) Chemicals and pharmacy 8 . 9 % % P a i n t s , v a r n i s h , l a c q u e r 1 1 . 1 1 .3 Shoe p o l i s h , shoe m a t e r i a l 2 . 7 0 . 5 Rubber - 0 . 1 Over the counter s a l e s 7 5 . 1 -M i s c e l l a n e o u s 2 . 2 0 . 2 The most important modern uses of t u r p e n t i n e occur i n the manufacture of s y n t h e t i c pine o i l , i n s e c t i c i d e s , s y n t h e t i c r e s i n and as a p a i n t t h i n n e r and a petroleum a d d i t i v e . The American S o c i e t y f o r T e s t i n g M a t e r i a l s has suggested standard s p e c i f i c a t i o n s t o a s s i s t i n the t a s k of grading s t e a m - d i s t i l l e d t u r p e n t i n e ( 1 ) . A.S.T.M. standards f o r s t e a m - d i s t i l l e d t u r p e n t i n e Max. Min. S p e c i f i c g r a v i t y at 20 deg. C 0 . 8 7 5 0.860 R e f r a c t i v e Index at 20 deg. C 1 . 4 7 8 1 . 4 6 5 Residue after*. P o l y m e r i z a t i o n w i t h 38 N s u l p h u r i c a c i d ; volume per cent 2 r e f r a c t i v e index at 20 deg. C 1 . 5 0 0 I n i t i a l b o i l i n g p o i n t at 760 -mm. p r e s s u r e , °C 160 150 D i s t i l l i n g below 170°C at 760 .mm. pressure per cent - 90 Summary of s a l i e n t p joints ( 1 ) Douglas f i r has a much lower r e s i n content than the pine species upon which the n a v a l s t o r e s i n d u s t r y i s based. This d i f f e r e n c e i s c o n s i d e r a b l y 22 i n c r e a s e d when comparison i s made between Douglas f i r and the s e l e c t e d h i g h l y r e s i n o u s lightwood of southern p i n e , which i s commonly used. (2) Heartwood has a much higher r e s i n content than sapwood, and t h i s r e s i n i s not u n i f o r m l y d i s t r i b u t e d throughout the wood of the t r e e . (3) Steam produces crude wood o i l i n small q u a n t i t y . A commercial e n t e r p r i s e employing onl y steam must have an abundant and r e a d i l y a v a i l a b l e supply of h i g h l y r e s i n o u s m a t e r i a l i n order to be p r o f i t a b l e . (4) S t e a m - d i s t i l l e d crude wood o i l i s mainly composed of t u r p e n t i n e and pine o i l . The b o i l i n g p o i n t ranges of these f r a c t i o n s are separate and d i s t i n c t , the t u r p e n t i n e being lower than t h a t of pine o i l . A s m a l l f r a c t i o n which has an in t e r m e d i a t e b o i l i n g range between the main c o n s t i t u e n t of t u r p e n t i n e (namely.i pinene) and pine o i l may a l s o be present. ( 5 ) Steam d i s t i l l a t i o n has only been commercially s u c c e s s f u l w i t h wood which has been broken down i n t o s mall c h i p s . No p r o d u c t i o n of n a v a l s t o r e s has been r e p o r t e d u s i n g wood m a t e r i a l i n the form of veneer. (6) Veneer d r y e r o p e r a t i n g temperatures s l i g h t l y exceed the upper l i m i t of the t u r p e n t i n e f r a c t i o n ' s b o i l i n g p o i n t range. (7) Increased speed of d i s t i l l a t i o n and decreased steam pressure reduces t o t a l y i e l d of crude o i l . (8) A good p o t e n t i a l market e x i s t s f o r wood na v a l s t o r e s products of s u i t a b l e q u a l i t y . There i s an i n c r e a s i n g a b s o r p t i o n by markets of wood n a v a l s t o r e s which have been manufactured as by-products of other wood u s i n g i n d u s t r i e s , but the market value of gum n a v a l s t o r e s i s s t e a d i l y d e c l i n i n g . (9) A company i n Canada which produces o n l y n a v a l s t o r e s apparently cannot compete s u c c e s s f u l l y w i t h the corresponding i n d u s t r y i n the U n i t e d S t a t e s because of a tremendous raw m a t e r i a l advantage i n the l a t t e r country. Veneer Drying Equipment and C o n d i t i o n s of Drying The i n v e s t i g a t i o n was conducted at the Vancouver Plywood D i v i s i o n of M a c M i l l a n , B l o e d e l and P o w e l l R i v e r L t d . i n Vancouver, B r i t i s h Columbia. A c t u a l sampling was performed on No. 1 and No. 2 d r y e r s of "B" m i l l i n t h i s d i v i s i o n . Both d r y e r s were i d e n t i c a l i n design and a s i m p l i f i e d p l a n of one of them can be found i n Appendix A. The d r y e r i s a c r o s s - c i r c u l a t i o n type c o n s t r u c t e d by the Moore Dry K i l n Company. The d r y i n g p r i n c i p l e i s t o have the a i r come o f f the f a n s , c i r c u l a t e across the top duct, through the h e a t i n g c o i l s and i n t o the plenum chamber at the s i d e of the d r y e r , between the doors and the veneer r o l l s . This a i r then passes across the veneer before r e t u r n i n g t o the f a n i n t a k e . The manner of c i r c u l a t i n g the a i r i s s i m i l a r i n every zone of the d r y e r , but i t s d i r e c t i o n of f l o w i s r e v e r s e d i n 24 a l t e r n a t e z o n e s . The d r y e r had s i x d e c k s and c o n s i s t e d o f s i x t e e n 6 3 - i n c h d r y i n g , and two 6 3 - i n c h c o o l i n g s e c t i o n s . T o t a l d i m e n s i o n s o f t h e d r y e r were as f o l l o w s : l e n g t h 117 f t . 8}£ i n . , h e i g h t 13 f t . 8 i n . , w i d t h 21 f t . 3 i n . E l e c t r i c power s u p p l y was 440 v o l t s , 60 c y c l e s and 3 p h a s e s . An e i g h t - b l a d e p r o p e l l e r - t y p e f a n , w i t h an o u t s i d e d i a m e t e r o f 42 i n . , and a r a t e d c a p a c i t y o f 30,000 c u . f t . p e r m i n u t e , p r o v i d e d c i r c u l a t i o n . E a ch f a n on t h e d r y e r s e c t i o n s was d r i v e n by a 10 hp G e n e r a l E l e c t r i c i n d u c t i o n motor a t speeds o f up t o 1760 rpm. E a c h o f t h e two f a n s i n the c o o l i n g s e c t i o n was d r i v e n by a 15 hp G e n e r a l E l e c t r i c i n d u c t i o n motor a t t h e same speed as u s e d i n t h e d r y e r . Steam was s u p p l i e d t h r o u g h one 4 - i n c h main and two 2}4-inch sub-mains a t a p r e s s u r e o f 260 pounds p e r square i n c h ( p s i ) . P r e s s u r e was r e c o r d e d on an a u t o m a t i c a l l y c o n t r o l l e d M o o r e - K i l n P r e s s u r e R e c o r d e r w h i c h had a range of z e r o t o 300 p s i . The d r y e r was e q u i p p e d w i t h 162 r e h e a t e r c o i l s o f 114-inch f i n p i p e . The c o i l f e e d s d e c r e a s e d i n d i a m e t e r from 2-in-, a t t h e g r e e n end t o l 1 A - i n . ' a t the d r y end. No steam t r a p s were p r e s e n t , t h e c o n d e nsate b e i n g d r a i n e d t h r o u g h check v a l v e s and c a r r i e d d i r e c t l y a l o n g a 6 - i n c h main t o t h e a d j o i n i n g C a n a d i a n White P i n e D i v i s i o n o f t h e same company, where i t was r e u s e d . A The d r y e r was e q u i p p e d w i t h a u t o m a t i c f e e d e r s , and speed r a t e s c o u l d range f r o m 4# t o 54 m i n u t e s . Normal d r y i n g speeds f o r D o u g l a s f i r , however, were as f o l l o w s : 25 Dryer times f o r Douglas f i r 1/10 i n . sap 17 min. 1/8 " " 22 » 1/6 '* " 29 11 3/16 " " 36 *' 1/7 11 " 25 " In w i n t e r the time i n the d r y e r f o r a l l t h i c k n e s s e s was one minute l o n g e r than the above times. S i x r o o f - v e n t i l a t o r stacks were l o c a t e d as shown on the p l a n i n Appendix A. These s t a c k s had a t o t a l h e i g ht of 24 f t . and an i n s i d e diameter of 19'-in";-. Because of the curvature of the f a c t o r y r o o f , the v e n t i l a t o r s t a c k s on No. 1 d r y e r p r o j e c t e d Tk f t . above the r o o f , w h i l e those on No. 2 d r y e r p r o j e c t e d only 4 f t . above the r o o f . Each stac k was equipped w i t h a damper s i t u a t e d 6 f t . above the top of the d r y e r . Each damper was c i r c u l a r i n c r o s s s e c t i o n (18-insh d i a m e t e r ) , and made of s o l i d sheet metal. This was welded to a )£-irch diameter pipe through which ran a metal r o d , t h i s rod being h e l d s e c u r e l y i n p o s i t i o n by set screws. For convenience of d e s c r i p t i o n , the s t a c k s were numbered, s t a r t i n g at the green end of the d r y e r , as shown i n Appendix B. Dampers were set as wide open as p o s s i b l e , p r o v i d e d s u i t a b l e zone temperatures c o u l d be maintained. I f the temperature i n any zone c o u l d not be maintained w i t h i n a range of 175 "bo 188 deg. C, then the damper was p r o g r e s s i v e l y c l o s e d to accomplish t h i s c o n d i t i o n . The most commonly used damper s e t t i n g s are shown i n Appendix C. 1/10 i n . c l e a r 71/z min. 1/8 " " 11 " 1/6 " " 16)6 " 3/16 " 11 18 1/7 " " 14 » 26 Moore-Kiln Recording Thermometers, each w i t h a range of 93 to 204 deg. C, measured the temperature of the a i r as i t emerged from the r e h e a t e r s . Thermometer bulbs were f i l l e d w i t h pure, theophane-free benzene vapour. Two 3-pen r e c o r d e r s were used f o r s e c t i o n s one to s i x , and seven to twelve, the former having tube l e n g t h s of 30 f t . , 70 f t . , and 60 f t . , and the l a t t e r 90 f t . , 70 f t . , and 110 f t . One 2-pen r e c o r d e r , used on s e c t i o n s t h i r t e e n to s i x t e e n , was equipped w i t h tubes which were 55 f t . and 65 f t . l ong r e s p e c t i v e l y . An examination of the twenty-four hour, a u t o m a t i c a l l y - r e c o r d e d temperature c h a r t s f o r the p e r i o d d u r i n g which a c t u a l sampling took p l a c e , gave the f i g u r e s f o r maximum, minimum, and average temperatures which are shown i n Appendix B. The temperature of zone one was low because the c i r c u l a t e d a i r i n t h i s zone was c o n t i n u a l l y i n contact w i t h a mass of c o l d green veneer which had j u s t entered the k i l n , w h i l e the temperature of zone e i g h t was lower because of i t s c l o s e p r o x i m i t y to the c o o l i n g s e c t i o n s of the d r y e r . P r i o r to sampling the d r y e r vapours, a b r i e f temperature study of No. 2 d r y e r was conducted. T h i s was done under normal o p e r a t i n g c o n d i t i o n s of d r y i n g , i n order to determine the temperature of these vapours both at the damper l e v e l and at the top of the stac k . The temperatures were measured by al"Brown P o r t a b l e Potentiometer (Model 126 W3) u s i n g a copper-constantan thermocouple. These temperatures were compared w i t h the maximum temperatures recorded on the Moore-Kiln Temperature Recorder c h a r t s at the exact times of measurement. R e s u l t s of 27 t h i s i n v e s t i g a t i o n are shown i n Appendix B. From the r e s u l t s i t i s seen t h a t there i s no temperature g r a d i e n t along the l e n g t h of the v e n t i l a t o r s t a c k . Any d i f f e r e n c e i n temperature between the a i r i n the sta c k and the a i r i n the d r y e r would be caused by vapour which had been p i c k e d up by the exhausted a i r d u r i n g d r y i n g o p e r a t i o n s . The v e l o c i t y of the a i r emerging from the sta c k v a r i e d through a f a i r l y wide range. These v e l o c i t i e s were measured by an Anemotherm A i r Meter (Model 60) manufactured by the Anemostat C o r p o r a t i o n of America, New York, and r e s u l t s o b tained by t h i s instrument are recorded i n Appendix C. A i r v e l o c i t y w i l l v a ry due t o s e v e r a l f a c t o r s , among which are damper s e t t i n g ; the p o s i t i o n of the stack i n r e l a t i o n to the fans ; i n i t i a l moisture content of the wood; temperature, humidity, and wind v e l o c i t y of the atmosphere at the top of the s t a c k ; speed, dimensions, and type of f a n used i n the d r y e r , and vapour pressure of the d r y e r zones. C o l l e c t i o n of the Dryer Vapour Sampling procedure Only the vapour which emerged from the top of the stacks of the d r y e r was c o l l e c t e d . Because No. 1 d r y e r handled only Douglas f i r sapwood, whereas No. 2 d r y e r used o n l y Douglas f i r heartwood, each dr y e r was sampled s e p a r a t e l y so t h a t a 28 comparison c o u l d be made between the amounts of e x t r a c t i v e recovered from each type of wood. The st a c k s were sampled i n d i v i d u a l l y so tha t a comparison of the r e l a t i v e y i e l d s from d i f f e r e n t p o i n t s on the d r y e r could be made, both along the l e n g t h of each d r y e r as w e l l as between corresponding l o c a t i o n s on the two d r y e r s . Each sample was gathered i n one continuous o p e r a t i o n which l a s t e d over a p e r i o d of s e v e r a l hours. Method of c o l l e c t i o n The apparatus was ere c t e d as i l l u s t r a t e d i n F i g u r e s 2 t o 6 ( i n c l u s i v e ) . The stack was capped w i t h a c i r c u l a r (24-inch diameter) metal l i d which had a c i r c u l a r h o l e , ~"4:'iriv. i n diameter, removed from i t s c e n t r e . This l i d was he l d down by heavy rocks which gave a f a i r l y t i g h t s e a l around the perime t e r of the l i d . A 4-inch diameter stove pipe elbow, made of n o n - i n s u l a t e d , g a l v a n i z e d metal, was i n s e r t e d i n t o the centre of the l i d before being connected to a 6 - f t . l e n g t h of stove p i p e , made of the same m a t e r i a l , and having the same diameter as the elbow. T h i s pipe l e d down to a condenser ( F i g u r e s 4,5,6) which was supported i n a h o r i z o n t a l p o s i t i o n by a c r a d l e made of 3/4-inch plywood. The condenser had three i n d i v i d u a l components.namely^ l i d , water j a c k e t , and condensing c o i l s . The f i r s t two were made of c a s t i r o n (3/4-inch t h i c k ) whereas the c o i l s were made of 1/2-inch ( i n s i d e diameter) copper t u b i n g . These three components 29 F i g . 3« C o n d e n s i n g a p p a r a t u s i n p o s i t i o n 30 F i g . 6 . Condenser (showing c o i l s ) 31 were h e l d f i r m l y together by t h i r t e e n 5/8-inch b o l t s . The condensing c o i l s were arranged i n f i v e rows, each row having a d i f f e r e n t l e n g t h . Measuring from the centre of the condenser towards the o u t s i d e , the numbers of tubes and t h e i r lengths were: Row No. of Tubes Length per Tube ( i n . ) Inner 12 " 39 2 11 40 3 10 42 4 9 44 Outer 6 45 The dimensions of the assembled condenser were as f o l l o w s : T o t a l l e n g t h 34 i n . Water j a c k e t diameter ( i n s i d e ) 10}£ i n . Upper r i m diameter 1454 i n . Diameter of o u t l e t s / i n l e t ' s : I n s i d e y/z i n . Outside 4 i n . Water was f e d to the condenser through a 5 0 - f t . l e n g t h of 3/4-inch p l a s t i c pipe connected to a f i r e hydrant which was l o c a t e d on the r o o f of the p l a n t . Both the condenser and the c r a d l e were mounted on a four-wheeled, f l a t - d e c k e d c a r t f o r ease of t r a n s p o r t a t i o n between s t a c k s . A 3#-ft. l e n g t h of 1-inch rubber hosepipe l e d from the o u t l e t v a l v e at the base of the condenser to a f i v e g a l l o n drum i n which the condensate was c o l l e c t e d . T h i s drum was f i t t e d w i t h a handle which f a c i l i t a t e d h a n d l i n g when i t was f u l l . While c o l l e c t i o n of condensate was i n pr o g r e s s , the top of the drum was completely sealed o f f from the atmosphere by means of a sheet of aluminum 32 wrapping f o i l . The period of time taken to c o l l e c t each sample of condensate was recorded, as we l l as the actual date and times of sampling. This l a t t e r information was necessary i n order to determine maximum temperatures during the period of sampling, these temperatures "being read subsequently from the Moore-Kiln Temperature Recorder charts. Instead of using the condenser i n the conventional way with water going into the surrounding water jacket and the vapour being condensed within the c o i l s , i t proved more advantageous to reverse t h i s procedure. This was done because of t e c h n i c a l d i f f i c u l t i e s which became evident during t r i a l runs with the equipment. The weight of the condenser, combined with the height of the stacks of No. 1 dryer above the roof of the plant, prevented the condenser from being used i n a v e r t i c a l p o s i t i o n , d i r e c t l y above the stack opening. Further d i f f i c u l t y was caused by the high v e l o c i t y of the emergent vapour. When the condenser was mounted h o r i z o n t a l l y i n i t s cradle and was connected to the stack opening i n the conventional manner, i t was found that the high v e l o c i t y of the emergent vapour created a back pressure at the entrance to the condenser c o i l s . This negative pressure forced some of the vapour back up the l e a d - i n pipe. As a r e s u l t of t h i s back flow., much of the vapour was forced out of the system at j o i n t s i n the pipe. When connected i n a reverse manner to that intended by the designer, and f i t t e d with a regulatory valve attached to i t s o u t l e t , the condenser was found to function with s a t i s f a c t o r y 33 e f f i c i e n c y . Consequently, i t was used i n t h i s manner throughout the i n v e s t i g a t i o n . Q u a n t i t a t i v e A n a l y s i s of the Condensate D e s c r i p t i o n of the condensate The condensate c o n s i s t e d of three general l a y e r s . The f i r s t of these was a l a y e r of s m a l l , i n d i v i d u a l s o l i d p a r t i c l e s of wood. These were y e l l o w ochre i n c o l o u r and covered the bottom of the r e c e i v i n g drum. Above t h i s was the main body of condensate c o n s i s t i n g of a c o l o u r l e s s , t r a n s l u c e n t aqueous mass. The surf a c e of the condensate was covered by a t h i n f i l m whose m u l t i - c o l o u r e d appearance was s i m i l a r to t h a t of g a s o l i n e f l o a t i n g on water. A l s o f l o a t i n g on the s u r f a c e . were s m a l l amounts of two d i f f e r e n t substances, both of which were t a c k y to the touch, and had a s l i g h t l y h i g h e r v i s c o s i t y than water. One of these substances was b l a c k i n c o l o u r w h i l e the other was p r u s s i a n green. Most of t h i s m a t e r i a l , however, was not f l o a t i n g on top of the condensate, but had become adhered to the metal w a l l of the c o n t a i n e r from which i t could not be e a s i l y removed by the aqueous condensate. Assumptions of the a n a l y s i s The f o l l o w i n g assumptions were made p r i o r t o the commencement of quantitative a n a l y s i s work: 34 (1) The s t e a m - d i s t i l l e d crude wood o i l i s composed of t u r p e n t i n e , and pine . " o i l . (2) Components are a l l simple substances which are completely s o l u b l e i n one another. (3) None of the components i s s o l u b l e i n water. These assumptions were based upon work done by Hawley and Palmer (18), and Palmer (24), and w h i l e they are not s t r i c t l y t r u e i n a l l cases, none of them i s s u f f i c i e n t l y i n c o r r e c t to have a s e r i o u s e f f e c t upon the r e s u l t s and c o n c l u s i o n s of the a n a l y s i s . A n a l y t i c a l procedure A diagrammatical o u t l i n e of the a n a l y s i s of the condensate would be as f o l l o w s : Condensate f i l t e r Aqueous Phase I S o l i d M a t e r i a l ether washes ether e x t r a c t i o n i n s e p a r a t o r y f u n n e l weigh Water-So ruble's] E t h e r - S o l u b l e s weight of suspended s o l i d s - evaporate 1000 ml. to dryness concentrate determine volume, s p e c i f i c g r a v i t y , r e f r a c t i v e index, b o i l i n g p o i n t range P i g . 7« A n a l y s i s of the condensate 35 A c t u a l a n a l y s i s was conducted i n a s e r i e s of stages: Stage 1. Removal of s o l i d m a t e r i a l This was done by means of vacuum f i l t r a t i o n . The condensate was poured i n t o Buchner-style p o r c e l a i n f i l t e r i n g f u n n e l . The c o l o u r l e s s , t r a n s l u c e n t f i ' l t r a t e was poured from the f i l t e r i n g f l a s k i n t o a 1000-ml. graduated c y l i n d e r which had a graduation i n t e r v a l of one m i l l i l i t e r . Each 1000-ml. q u a n t i t y , or measured p o r t i o n t h e r e o f , was then t r a n s f e r r e d f o r storage t o a short-necked, narrow-mouthed, 2450-ml. round b o t t l e equipped w i t h a p l a s t i c screw cap. When the r a t e of f i l t r a t i o n d e c l i n e d a p p r e c i a b l y , the Buchner f u n n e l was t r a n s f e r r e d t o another f i l t e r i n g f l a s k of s i m i l a r c a p a c i t y and des i g n t o t h a t a l r e a d y used, and the p r e c i p i t a t e was washed w i t h an ether s o l v e n t , u s i n g vacuum f i l t r a t i o n . A minimum of three washes was a p p l i e d , and washing was continued u n t i l the f i l t r a t e became c o l o u r l e s s . The f u n n e l was f i l l e d almost t o the r i m f o r each wash. The s o l v e n t used was reagent grade petroleum e t h e r w i t h a b o i l i n g range of 30 t o 60 deg. C ( l i g r o i n e ) . The condensates from stacks number 4 and 6 of No. 2 d r y e r were t r e a t e d throughout w i t h p u r i f i e d dry e t h y l e t h e r . Eor s i m p l i c i t y , however, only petroleum ether w i l l be named as th© s o l v e n t used i n t h i s i n v e s t i g a t i o n . The c l e a r , amber-coloured s o l v e n t was was t r a n s f e r r e d from the f i l t e r i n g f l a s k to a separate 2450-ml. b o t t l e from t h a t used f o r the i n i t i a l f i l t r a t e . 36 Stage 2. Weight d e t e r m i n a t i o n of s o l i d m a t e r i a l A l l f i l t e r papers c o n t a i n i n g the e n t i r e s o l i d p o r t i o n from one sample of condensate were p l a c e d i n a c l e a n , d ry, weighed, P e t r i d i s h . The d i s h was then weighed again before being p l a c e d , f o r a minimum of f o r t y - e i g h t hours, i n an oven which was kept at a constant temperature of 105 deg. C. P e r i o d i c check weighings were made, and when l o s s of weight became n e g l i g i b l e , the d i s h and contents were reweighed, the weight of the f i l t e r paper deducted, and the exact weight of the s o l i d . ^ m a t e r i a l c a l c u l a t e d . A l l weighings were done us i n g a Spoerhase A n a l y t i c a l Rapid Balance (Type No. 10). Stage 3« S e p a r a t i o n of e t h e r - s o l u b l e s from water -s o l u b l e s Two globe-shaped separatory f u n n e l s were used f o r t h i s purpose. One had a c a p a c i t y of 2000- ml. w h i l e the other had o n l y a 250-ml. c a p a c i t y . The f i l t r a t e from Stage 1. was poured through a short-stemmed f i l t e r f u n n e l i n t o the separatory f u n n e l , f o l l o w e d by a s u b s t a n t i a l q u a n t i t y of the same type of s o l v e n t which was used i n Stage 1. The mixture i n the f u n n e l was then shaken v i g o r o u s l y before b e i n g allowed to s e t t l e i n t o an upper s o l v e n t l a y e r and a lower aqueous l a y e r . The w a t e r - s o l u b l e l a y e r was drawn o f f i n t o 800^ml. beakers and the e t h e r - s o l u b l e l a y e r was run o f f i n t o another 2450-ml. b o t t l e . Removal of the water was done q u i t e s l o w l y i n order to avoid a w h i r l p o o l e f f e c t i n the f u n n e l , which would have r e s u l t e d i n a 37 l o s s of some e t h e r - s o l u b l e m a t e r i a l . The w a t e r - s o l u b l e p o r t i o n i n the beakers was again p l a c e d i n the separatory f u n n e l and the procedure repeated before t h i s w a t e r - s o l u b l e p o r t i o n was d i s c a r d e d . The amber-coloured wash m a t e r i a l from Stage 1. was a l s o p l a c e d i n the separatory funnel along w i t h some of the i n i t i a l f i l t r a t e and f r e s h s o l v e n t , and the s e p a r a t i o n process conducted i n a s i m i l a r manner to t h a t d e s c r i b e d . Stage 4 . Recovery of s o l v e n t Much of the s o l v e n t used i n the a n a l y s i s was recovered f o r re-use by the f o l l o w i n g method: Some of the e t h e r - s o l u b l e s o l u t i o n was p l a c e d i n a 1 0 0 0 -ml. long-necked, round-bottomed b o i l i n g f l a s k . This was f i t t e d to a f l a s h - e v a p o r a t o r , and the eth e r recovered a t a temperature not exceeding 37 deg. C and at a vacuum of 15 to 20 inches of mercury. The vandyke-brown-co l o u r e d mixture of crude o i l and s o l v e n t was t r a n s f e r r e d to a 4 5 0 -ml. short-necked, narrow-mouthed, round b o t t l e equipped w i t h a p l a s t i c screw cap, and the b o t t l e l a b e l l e d w i t h the app r o p r i a t e sample number. Stage 5 ' Determination of the weight of suspended s o l i d s i n the w a t e r - s o l u b l e p o r t i o n E x a c t l y 1000--ml. of the w a t e r - s o l u b l e s o l u t i o n which was d i s c a r d e d from Stage 3« were b o i l e d to dryness i n a 250-ml. beaker whose i n i t i a l c l e a n d r y weight was known. The beaker was weighed a f t e r e v a p o r a t i o n had been completed, and the weight of the l i g h t r e d , s o l i d m a t e r i a l contained i n i t was 38 ca l c u l a t e d i n r e l a t i o n to 100 ml. of t h i s water-soluble portion. Because of the small t o t a l volume c o l l e c t e d from number 6 stack on No. 1 dryer, only 200 ml. of the water-soluble s o l u t i o n was bo i l e d to dryness. Before heat was applied, the aqueous l i q u i d was colourless and translucent, but s h o r t l y t h e r e a f t e r i t turned a pale chrome-yellow colour. This colour became darker as more sol u t i o n was evaporated from the beaker, and ended as a l i g h t red, s o l i d material. Stage 6.Determination of ether-soluble content The ether-soluble material from Stage 4-. was placed i n a 250-ml. d i s t i l l i n g f l a s k . This f l a s k was connected to a L i e b i g condenser which was made of heat r e s i s t a n t glass. A 100-ml. graduated c y l i n d e r with graduations at 0.1-ml. i n t e r v a l s was used to c o l l e c t the ether solvent. A total-immersion, nitrogen-f i l l e d thermometer, graduated at 1 deg. C i n t e r v a l s , and with a range of zero to 200 deg. C, was inser t e d i n the neck of the d i s t i l l i n g f l a s k so that the top of the mercury bulb was l e v e l with the bottom of the side tube. Heat was applied by a bunsen burner to the base of the d i s t i l l i n g f l a s k . Maximum temperature of evaporation was kept below 80 deg. C. Solvent was d i s t i l l e d o f f and the dark brown material l e f t i n the d i s t i l l i n g f l a s k was poured out into a 10-ml. graduated c y l i n d e r , which had 0.2-ml. graduation i n t e r v a l s , whereupon i t s volume was measured. Allowance had to be made at t h i s stage f o r the very small amount of material which did not enter the graduated c y l i n d e r because of i t s surface tension. 39 A f t e r measurement, t h i s m a t e r i a l was t r a n s f e r r e d i n t o a 120-ml. French square b o t t l e equipped w i t h a p l a s t i c screw cap. The d i s t i l l i n g f l a s k and graduated c y l i n d e r were washed out w i t h petroleum e t h e r s o l v e n t and t h i s wash m a t e r i a l was a l s o poured i n t o the bottle'. This b o t t l e was used to c o l l e c t a l l other s o l u b l e m a t e r i a l coming from one d r y e r so t h a t at the c o n c l u s i o n of t h i s stage of the a n a l y s i s , the t o t a l amount of e t h e r - s o l u b l e m a t e r i a l c o l l e c t e d from No. 1 d r y e r was i n one b o t t l e , w h i l e the corresponding m a t e r i a l f o r No. 2 d r y e r was contained i n a second b o t t l e . Stage 7» Determination of b o i l i n g p o i n t ranges M i c r o - d i s t i l l a t i o n equipment had to be used f o r t h i s work because of the s m a l l q u a n t i t y of e t h e r - s d l u b l e m a t e r i a l obtained i n Stage 6. A connecting three-way tube w i t h a 75-degree s i d e tube was i n s e r t e d i n the top of a 2^>-ml. micro b o i l i n g f l a s k which had a c o n i c a l bottom. T h i s f l a s k was immersed i n a b a t h of C P . grade b u t y l p h t h a l a t e ( b o i l i n g p o i n t of 340 deg. C) so t h a t the l e v e l of the bath was above t h a t of the m a t e r i a l i n s i d e the f l a s k . A L i e b i g micro condenser was attached to the side tube. A 10-ml. graduated c y l i n d e r w i t h 0.2-ml. graduation i n t e r v a l s was used as a r e c e i v i n g c y l i n d e r . A n i t r o g e n - f i l l e d thermometer was f i t t e d i n t o the top of the connecting tube so t h a t the top of the mercury bulb was l e v e l w i t h the bottom of the s i d e tube. T h i s thermometer was graduated i n 2 deg. C i n t e r v a l s w i t h a range of zero to 250 deg. C. 40 The e t h e r - s o l u b l e m a t e r i a l was poured i n t o the b o i l i n g f l a s k and a s m a l l piece of pumice added to promote smooth d i s t i l l a t i o n i n case the sample contained any d i s s o l v e d or suspended water. The f l a s k was then attached to the apparatus. Heat from a bunsen flame was a p p l i e d c a u t i o u s l y to the bath. The temperature was r a i s e d to 70 deg. C and a l l d i s t i l l a t e c o l l e c t e d up to t h i s p o i n t was d i s c a r d e d because i t mainly c o n s i s t e d of the ether s o l v e n t . The f l a s k was allowed to c o o l s l i g h t l y , a f t e r which i t was removed and had more e t h e r - s o l u b l e m a t e r i a l added to i t , T h i s procedure was continued u n t i l a l l e t h e r - s o l u b l e m a t e r i a l had been poured i n t o the b o i l i n g f l a s k , and a l l d i s t i l l a t e up to 70 deg. C was d i s c a r d e d . The temperature was then r a i s e d c a u t i o u s l y , and the i n i t i a l b o i l i n g p o i n t was taken as the thermometer r e a d i n g at the i n s t a n t when the f i r s t drop f e l l from the end of the condenser. When the temperature reached 150 deg. C, the flame was removed, and the volume of d i s t i l l a t e i n the graduated c y l i n d e r recorded. This m a t e r i a l was re t u r n e d to the o r i g i n a l b o t t l e which had contained the e t h e r - s o l u b l e m a t e r i a l . The flame was then r e p l a c e d under the bath, and the temperature r a i s e d v e r y s l o w l y u n t i l 170 deg. C was reached, whereupon i t was again removed. The volume of t h i s f r a c t i o n was recorded a f t e r which i t was poured i n t o a s m a l l g l a s s capsule f o r f u r t h e r examination. The flame was then r e p l a c e d , and the volume of d i s t i l l a t e was measured between 170 and 200 deg. C before 41 r e t u r n i n g both t h i s f r a c t i o n , and the f r a c t i o n above 200 deg. C which remained i n the d i s t i l l i n g f l a s k , to the b o t t l e which had contained the e t h e r - s o l u b l e m a t e r i a l . D i s t i l l a t i o n took p l a c e s l o w l y and f a i r l y u n i f o r m l y throughout these three temperature ranges. Stage 8. Determination of s p e c i f i c g r a v i t y and r e f r a c t i v e index at 20 deg. C E x a c t l y 0.5 ml. of the c l e a r , pale lemon-yellow f r a c t i o n w i t h the b o i l i n g p o i n t range of 150 and 170 deg. C was p i p e t t e d i n t o a c l e a n dry weighed b o t t l e and i t s weight determined on an A n a l y t i c a l Rapid Balance. S p e c i f i c g r a v i t y c o u l d be c a l c u l a t e d from t h i s i n f o r m a t i o n . R e f r a c t i v e index of the same m a t e r i a l was measured on an Abbe Refractometer. The temperature of the instrument room where both measurements were made was e x a c t l y 20 deg. C, so t h a t no c o r r e c t i o n of the r e s u l t s was necessary because of temperature d i f f e r e n c e . C a l c u l a t i o n of R e s u l t s T o t a l condensate - ( t h e o r e t i c a l l o s s of moisture i n d r y i n g ) The r e s u l t s obtained from the a n a l y s i s of the condensate are shown i n Appendices D and E. 42 The i n i t i a l moisture content of Douglas f i r sapwood i s approximately 116 per cent w h i l e t h a t of the heartwood of the same s p e c i e s i s approximately 40 per cent (26). A l l veneer i s d r i e d to a maximum moisture content of 5 per cent. The average s p e c i f i c g r a v i t y of Douglas f i r (green volume, oven-dry weight of wood) i s 0.45. T o t a l weight of wood at any moisture content can he c a l c u l a t e d from the formula: W = WQ (1 + M/100) where W = weight of wood at moisture content M. WQ = oven-dry weight of wood. The oven-dry weight of one cub i c f o o t of Douglas f i r i s 0.45 x 62.4 = 28.1 l b . Using the above formula, t h e r e f o r e , the moisture l o s s e s i n d r y i n g the d i f f e r e n t types of Douglas f i r wood to a 5 per cent moisture content w i l l be as shown below: (Weights i n l b . per cu. f t . ) w '. , , Wt. at i n i t i a l M.C. Wt. at f i n a l M.C. w«;ign-c Loss Sapwood 60.7 29-5 31.2 Heartwood 39.3 29-5 9.8 The average amounts of wood used i n each d r y e r are as f o l l o w s : No. 1 d r y e r = 25,000 square f e e t of 1/16-in. veneer per hour, or approximately 130 cubic f e e t per hour. No. 2 d r y e r = 50,000 square f e e t of 1/16-in. veneer per hour, or approximately 260 cubic f e e t per hour. 43 The t h e o r e t i c a l weight l o s s e s from these d r y e r s are? (Conversion f a c t o r : 1 l h . = 453*6 gnr.) .• No. 1 d r y e r = 130 x 31.2 = 4056 l h . per hour = 1,840 kg. per hour No. 2 d r y e r = 260 x 9.8 = 2548 l b . per hour = 1,156 kg. per hour Table 1. R e l a t i o n s h i p between t h e o r e t i c a l and experimental y i e l d s of t o t a l condensate (a) (b) (c) (d) Tot . condensate T h e o r e t i c a l wt. % of (c) Dryer c o l l e c t e d per hour l o s s per h r . on a c t u a l l y No. Stack Amount % of t o t . amount b a s i s of (b) c o l l e c t e d . •'• (gm.) (kg.) 1 1 197 7 129 0 . 1 5 2 257 10 184 0.14 3 743 28 515 0.14 4 1221 46 846 0.14 5 210 8 14? 0.14 6 14 1 19 0 . 0 7 T o t a l 100 1,840 Av:. , 0.14 2 1 318 18 208 0 . 1 5 2 365 20 231 0.16 3 242 14 161 0 . 1 5 4 600 33 382 0.16 5 189 11 127 0 . 1 5 6 78 4 46 0 . 1 7 T o t a l 100 1,156 Av:. • 0.15 44 I x p l a n a t i o n of Table 1. Column ( a ) : The p e r i o d of time taken to c o l l e c t the t o t a l condensate v a r i e d from sta c k t o sta c k . Because d i f f e r e n t l e n g t h s of time were used f o r t h i s work, i t was necessary to c a l c u l a t e each y i e l d of t o t a l condensate i n terms of the same common time b a s i s before any comparison of r e l a t i v e y i e l d s from the s t a c k s could be made. T o t a l condensate f i g u r e s were t h e r e f o r e c a l c u l a t e d on the b a s i s of t o t a l q u a n t i t y c o l l e c t e d per hour. T h i s was done by d i v i d i n g column ( c ) , Appendix E, by column ( a ) i n the same Appendix. -As the condensate c o n s i s t e d l a r g e l y of water i t s weight was considered to-be 1 gram per m i l l i l i t e r . Column ( b ) : T h i s s t a t e s the amount of t o t a l condensate c o l l e c t e d per hour from each s t a c k expressed as a percentage of the t o t a l amount of condensate c o l l e c t e d per hour from the e n t i r e d r y e r . Column ( c ) : The t h e o r e t i c a l weight l o s s f o r the wood i n the d r y e r d i s t r i b u t e d between the d r y e r stacks on the b a s i s of the percentages i n column ( b ) . T h i s gives an i n d i c a t i o n of the t h e o r e t i c a l amount of moisture which should be c o l l e c t e d from each stack of the d r y e r . Column ( d ) : The amount of t o t a l condensate a c t u a l l y c o l l e c t e d (a) expressed as a percentage of the t h e o r e t i c a l amount which could be c o l l e c t e d ( c ) . . . T o t a l v o l a t i l e o'dl f r a c t i o n of the Condensate T h e o r e t i c a l d e t e r m i n a t i o n of the amount of v o l a t i l e o i l d r i v e n o f f i n steaming can be made i f the ether s o l u b i l i t y and the composition of the r e s i n are known. The ether s o l u b i l i t y of Douglas f i r was found by Hawley ( 1 7 ) to be 1 . 0 2 per cent of the i n t i a l oven-dry weight of wood. In h i s work on Douglas f i r , Schorger ( 2 9 ) concluded t h a t the v o l a t i l e o i l comprised o n l y 2 9 * 5 per cent (average) of the heartwood o l e o r e s i n and 2 2 . 7 per cent of the sapwood o l e o r e s i n . Using Hawley's e t h e r s o l u b i l i t y f a c t o r as a measure of the average r e s i n content of both the heartwood and sapwood of Douglas f i r , i t i s seen t h a t , on the b a s i s of Schorger's r e s u l t s , the amount of v o l a t i l e o i l i n heartwood w i l l be approximately 0 . 3 0 per cent of the oven-dry weight of t h i s type of wood. The corresponding value f o r sapwood w i l l be 0 . 2 3 per cent of the oven-dry weight of sapwood. The assumption t h a t none of the n o n - v o l a t i l e r o s i n m a t e r i a l comes o f f i s not s t r i c t l y c o r r e c t . As o n l y a very s m a l l amount of t h i s m a t e r i a l might be present (16, 1 7 , 2 3 ) i t 46 i s f e l t t h a t i t s e x c l u s i o n w i l l n o t have a s e r i o u s e f f e c t upon d e d u c t i o n s and c o n c l u s i o n s o f t h e a n a l y s i s . No. 1 d r y e r : The average o v e n - d r y w e i g h t o f Douglas f i r = 28.1 l b . p e r cu. f t . The y i e l d o f v o l a t i l e o i l = 28.1 x 0.23% = 0.065 l b . p e r cu. f t . = 29.5 gin. p e r c u . f t . S p e c i f i c g r a v i t y o f v o l a t i l e o i l = 0.863 ( T a b l e 6) Weight o f an e q u a l volume o f w a t e r = 29«5 * 0.863 gm. = 34.2 gm. Y i e l d o f v o l a t i l e o i l , t h e r e f o r e , e q u a l s 34.2 m l . p e r c u . f t . Volume o f wood u s e d i n d r y e r = 130 c u . f t . p e r hour T h e o r e t i c a l volume o f v o l a t i l e o i l d r i v e n o f f f r o m sapwood, t h e r e f o r e , w i l l be 34.2 x 130 = 4446 m l . p e r hour No. 2 d r y e r : Y i e l d o f v o l a t i l e o i l = 28.1 x 0.30% = 0.084 l b . p e r c u . f t . = 38.1 gm. p e r c u . f t . Volume y i e l d o f v o l a t i l e o i l s = 38.1 * 0.863 = 44.1 ml. p e r c u . f t . o f wood Volume o f wood used i n the d r y e r = 260 c u . f t . p e r hour T h e o r e t i c a l volume o f v o l a t i l e o i l d r i v e n o f f from heartwood, t h e r e f o r e , w i l l be 44.1 x 260 = 11,466 m l . p e r hour The a c t u a l y i e l d s o f e t h e r - s o l u b l e s w h i c h were c o l l e c t e d f r o m t h e d r y e r s have been c a l c u l a t e d f r o m A p p e n d i x E t o g i v e t h e r e s u l t s shown i n T a b l e 2. 4? Table 2. V o l a t i l e o i l recovered from the d r y e r s (a) ( b ) ( O % of t o t a l V o l a t i l e o i l Dryer Stack V o l a t i l e o i l v o l . of o i l f r a c t i o n as % No. No. recovered per h r recovered of t o t a l condensate (ml.; 1 1 0.04 4 0.01 2 0.13 14 0.05 3 0.28 29 0.04 4 0.39 40 0.03 5 0.07 7 0.03 6 0.06 6 0.43 T o t a l 0.97 100 Av... 0.10 2 1 0.07 9 0.02 2 0.09 11 0.03 3 0.21 26 0.09 4 0.33 41 0.06 5 0.06 8 0.03 6 0.04 5 0.05 T o t a l 0.80 100 Av.. • 0.05 E x p l a n a t i o n of Table 2. Column ( a ) : The e t h e r - s o l u b l e f r a c t i o n of the t o t a l condensate recovered from each stack was c a l c u l a t e d on the b a s i s of q u a n t i t y recovered per hour, f o r the same reason t h a t was given f o r doing s i m i l a r c a l c u l a t i o n s to the f i g u r e s f o r t o t a l condensate (Table 1 ) . R e s u l t s i n t h i s column were c a l c u l a t e d from Appendix E 48 by d i v i d i n g the f i g u r e s i n column (e) by those i n column ( a ) . Column ( b ) : T h i s i s the amount of v o l a t i l e o i l c o l l e c t e d per hour from each stack expressed as a percentage of the t o t a l amount of these o i l s c o l l e c t e d per hour from the e n t i r e d r y e r . Column ( c ) : The volume of v o l a t i l e o i l s c o l l e c t e d per hour (a) c a l c u l a t e d as a percentage of the t o t a l volume of condensate c o l l e c t e d per hour (column ( a ) , Table 1 ) . T h e o r e t i c a l percentage of v o l a t i l e o i l s recovered i n the experiment. No. 1 d r y e r : T h e o r e t i c a l volume of v o l a t i l e o i l s d r i v e n g f f was c a l c u l a t e d to be 4446 ml. per hour. A c t u a l volume c o l l e c t e d = 0.97 ml« per hour T h e o r e t i c a l recovery = 0.97 + 4446 = 0.022% No. 2 d r y e r : T h e o r e t i c a l recovery = 0.80 + 11,466 = 0.007% These are assessments of the percentage r e c o v e r i e s achieved i n the experiment based upon the ether s o l u b i l i t y c a l c u l a t i o n s of Hawley ( 1 7 ) , and the work done by Schorger (29) on the composition of Douglas f i r o l e o r e s i n . 49 The most important l i m i t a t i o n s of t h i s t h e o r e t i c a l data have a l r e a d y been p o i n t e d out, but t h i s method g i v e s some i n d i c a t i o n of the p r o p o r t i o n of v o l a t i l e o i l m a t e r i a l which was probably recovered i n the experiment. An assessment of the p r o p o r t i o n of v o l a t i l e o i l m a t e r i a l which was recovered i n the experiment can a l s o be made by comparing the experimental r e s u l t s w i t h y i e l d s from a c t u a l commercial d i s t i l l a t i o n work which has been done i n the p a s t . For t h i s purpose the y i e l d s from steam and s o l v e n t d i s t i l l a t i o n of o r d i n a r y stumpwood of Douglas f i r (13) w i l l be used as a standard, as t h i s wood raw m a t e r i a l most c l o s e l y approximates to the r e s i n content of the wood from the bole of the t r e e which was used to manufacture veneer. The heartwood-to-sapwood r a t i o i n t h i s stumpwood i s not known. As the stumpwood i s termed " o r d i n a r y " i t i s f e l t t h a t i t s moisture content w i l l be between the green c o n d i t i o n and the a i r - d r y (12 per cent) c o n d i t i o n . Weight of wood at 12 per cent moisture content ( a i r - d r y ) = 31.5 l b . per cu. f t . Weight of wood at 116 per cent moisture content (green sapwood) = 60 .7 l b . per cu. f t . Weight of wood at 40 per cent moisture content (green heartwood) = 39*3 l b . per cu. f t . The r e s u l t s of the steam and s o l v e n t e x t r a c t i o n of o r d i n a r y Douglas f i r stumpwood (13) are recorded on page 18. The t o t a l o i l f r a c t i o n recovered was 0.9 U.S. g a l . = 7«2 U.S. p i n t s = 3430 ml. (1000 ml. = 2.1 U.S. p i n t s ) . T h i s was 50 e x t r a c t e d from 3800 l b . of wood, t h e r e f o r e , 1 gram of wood should y i e l d 0.002 ml. of v o l a t i l e o i l . No. 1 d r y e r : (1) Green wood: T o t a l weight of wood d r i e d per hour. = 60 . 7 x 130 = 7891 l b . per hour = 3 ,579,280 gm. per hour Y i e l d of stump v o l a t i l e o i l = 3 ,579,280 x 0.002 = 7160 ml. per hour Y i e l d from the d r y e r = 0.97 ml. per hour Recovery = 0.97 + 7160 = 0.01 per cent. (2) A i r - d r y wood: Recovery = 0.97 3715 = 0 . 0 2 per cent. No. 2 d r y e r : (1) Green wood: T o t a l weight of wood d r i e d per hour = 39.3 x 260 = 10,218 l b . per hour = 4,634,780 gm. per hour Y i e l d of stump v o l a t i l e o i l = 4,634,780 x 0.002 = 9,270 ml. per hour Y i e l d from the d r y e r = 0.80 ml. per hour Recovery = 0.80 + 9,270 = 0.0086 per cent. (2) A i r - d r y wood: Recovery = 0.80 * 7430 = 0.01 per cent. The c a l c u l a t i o n s of v o l a t i l e o i l from the veneer d r y e r s based on the y i e l d s recorded from o r d i n a r y Douglas f i r stumpwood show d i s t i n c t s i m i l a r i t y t o the corresponding c a l c u l a t i o n s u s i n g the data of Hawley and Schorger. E x a c t l y s i m i l a r r e c o v e r i e s occur i f the sapwood of o r d i n a r y Douglas f i r stumpwood was i n an a i r - d r y c o n d i t i o n w h i l e the heartwood 51 was i n a green s t a t e . One p o s s i b l e e x p l a n a t i o n f o r s i m i l a r i t y i n r e c o v e r i e s i s t h a t the o r d i n a r y stumpwood which was d i s t i l l e d i n a commercial steam and s o l v e n t p l a n t was f r e s h c u t , green and c o n s i s t e d l a r g e l y of heartwood, w i t h o n l y a narrow zone of sapwood being present. The y i e l d s from o r d i n a r y Douglas f i r stumpwood w i l l be used f o r f u r t h e r c a l c u l a t i o n s because these are based on a c t u a l r e c o v e r i e s and are not merely t h e o r e t i c a l amounts which might be recovered. I t i s a l s o f e l t t h a t r e s u l t s c a l c u l a t e d on the b a s i s of green wood w i l l be more r e a l i s t i c of the a c t u a l c o n d i t i o n of the wood which was d i s t i l l e d . The t h e o r e t i c a l y i e l d of v o l a t i l e o i l from the d r y e r s based on o r d i n a r y Douglas f i r stumpwood r e c o v e r i e s are t h e r e f o r e as f o l l o w s : No. 1 d r y e r = 7160 ml. per hour No. 2 d r y e r = 9270 ml. per hour These y i e l d s can be su b d i v i d e d i n t o t u r p e n t i n e and pine o i l f r a c t i o n s on the b a s i s of the a c t u a l r e c o v e r i e s which were achieved from the e x t r a c t i o n of t h i s same stumpwood m a t e r i a l . Table 3. R e l a t i o n s h i p between t h e o r e t i c a l and experimental y i e l d s of v o l a t i l e o i l s . No. 1 Dryer No. 2 Dryer T o t a l v o l a t i l e o i l (ml. per hour) 7,160 9,270 Recovery from d r y e r (per cent) 0.01 0.008 Turpentine f r a c t i o n (ml. per hour) 4,-770 6,180 Recovery from d r y e r (per cent) 0.002 0 .0005 Pine o i l f r a c t i o n (ml. per hour) 2,390 3 , 0 9 0 Recovery from d r y e r (per cent) Not known Not known 5 2 E x p l a n a t i o n of Table 3 R e s u l t s of the work done on Douglas f i r stumpwood ( 1 3 ) show the t o t a l v o l a t i l e o i l m a t e r i a l to c o n s i s t of 6 7 per cent t u r p e n t i n e and 3 3 per cent pine o i l . The above volumes were c a l c u l a t e d on the b a s i s of these percentages, u s i n g values f o r t h e o r e t i c a l v o l a t i l e o i l y i e l d s of 7 1 6 0 ml. per hour f o r No. 1 d r y e r , and 9 , 2 7 0 ml. per hour f o r No. 2 d r y e r . The t o t a l amount of v o l a t i l e o i l , and the volume of the t u r p e n t i n e f r a c t i o n ( b o i l i n g p o i n t range of 1 5 0 to 1 7 0 deg. C) of t h i s v o l a t i l e o i l were determined from data i n Appendix D and Table 2 , and these amounts were c a l c u l a t e d as a percentage of the t h e o r e t i c a l v o l a t i l e o i l y i e l d . Summary of c a l c u l a t i o n s The f o l l o w i n g i s a summary of the volume y i e l d s obtained by the i n v e s t i g a t i o n . A l s o shown are t h e o r e t i c a l volumes which have been c a l c u l a t e d i n order to provide standards f o r comparison between a c t u a l y i e l d s and the volumes which t h e o r e t i c a l l y could have been recovered. r 53 Table 4. Summarized comparison between t h e o r e t i c a l and a c t u a l y i e l d s (Volumes expressed . i n U.S. s a l I o n s per 24-hour dav) Dryer No. T h e o r e t i c a l y i e l d A c t u a l y i e l d Percentage recovered 1 T o t a l condensate T o t a l v o l a t i l e o i l s Turpentine Pine o i l 11,590 45 30 15 16.5 0.006 0.0006 0 . 1 0.01 0.002 2 T o t a l condensate T o t a l v o l a t i l e o i l s Turpentine Pine o i l 7280 58 38 20 11.4 0 . 0 0 5 0.0002 0 . 1 0 .009 0.001 D i s c u s s i o n of R e s u l t s Assumptions i n the t h e o r e t i c a l c a l c u l a t i o n s S e v e r a l important assumptions were made when c a l c u l a t i n g and a s s e s s i n g the r e s u l t s of the i n v e s t i g a t i o n . I n i t i a l moisture contents of both sapwood and heartwood veneer were not measured. The moisture content f i g u r e s which have been used i n c a l c u l a t i n g the t h e o r e t i c a l l o s s of moisture i n d r y i n g , t h e r e f o r e , are averages which were obtained by Peck (26) over a l a r g e number of samples. The p r o x i m i t y of these values to the average moisture content of the veneer d u r i n g the p e r i o d i n which the vapour was c o l l e c t e d i s not known. I f Peck's averages are h i g h e r than the amount of moisture which was a c t u a l l y present i n the veneer, then a l a r g e r p r o p o r t i o n 54 of the vapour would have been c o l l e c t e d than i s i n d i c a t e d by Table 1 . The amounts of veneer p a s s i n g through the dr y e r s per hour were estimated, but these estimates were considered by the management of the p l a n t to be very r e p r e s e n t a t i v e of the average amounts of sapwood and heartwood veneer which are handled each day i n Mo. 1 and Ro. 2 d r y e r s r e s p e c t i v e l y . The l i m i t a t i o n s of both Hawley's ether s o l u b i l i t y v alue and Schorger's data on v o l a t i l e o i l s have a l r e a d y been p o i n t e d out. One most important a d d i t i o n to these l i m i t a t i o n s , however, i s the f a c t t h a t these f i g u r e s were d e r i v e d from stumpwood and not from the o r d i n a r y wood i n the bo l e of the t r e e from which veneer i s made. Stumpwood has a h i g h e r r e s i n content. In l o n g l e a f pine f o r example, o r d i n a r y sapwood co n t a i n s 2 per cent r e s i n , heartwood 7 t o 10 per cent r e s i n , w h i l e the heartwood of the stumpwood c o n t a i n s 25 per cent or more r e s i n . There i s , t h e r e f o r e , a s u b s t a n t i a l d i f f e r e n c e betwe the amount of r e s i n which i s present between the wood of the stump and the wood of the bole of the t r e e . In t h i s i n v e s t i g a t i o n the recovery of v o l a t i l e o i l from, wood which has the l e a s t r e s i n content has had to be r e l a t e d to a corresponding t h e o r e t i c a l recovery from the most r e s i n o u s wood because of a l a c k of more a p p l i c a b l e data from p r e v i o u s work done w i t h Douglas f i r i n t h i s f i e l d . Another assumption which has been made i s t h a t the p r o p o r t i o n of v o l a t i l e o i l i n the e t h e r - s o l u b l e e x t r a c t i v e m a t e r i a l i s f a i r l y constant. In the case of maritime p i n e , however, i t has been r e p o r t e d t h a t the v o l a t i l e o i l content of the e t h e r - s o l u b l e e x t r a c t i v e s may vary from 0 . 5 7 per cent to as low as 0 . 0 7 per cent ( 5 1 ) , and no records are a v a i l a b l e to s u b s t a n t i a t e or deny the p o s s i b i l i t y of a v a r i a t i o n of s i m i l a r magnitude o c c u r r i n g i n the e t h e r - s o l u b l e e x t r a c t i v e s of Douglas f i r . The assumption t h a t none of the n o n - v o l a t i l e r o s i n m a t e r i a l comes o f f was a l s o mentioned above. Should any of t h i s r o s i n be present i n the ether s o l u b l e p o r t i o n of the condensate, t h i s w i l l decrease the y i e l d of v o l a t i l e o i l s Y/hich was thought t o have been c o l l e c t e d . While steam d i s t i l l a t i o n i s known to produce the lowest v o l a t i l e o i l y i e l d of a l l commercial d i s t i l l a t i o n p r ocesses, the standards which were c a l c u l a t e d f o r the assessment of these y i e l d s were based on data d e r i v e d from .more e f f i c i e n t e x t r a c t i v e processes. T o t a l condensate From Table 1 i t can be seen t h a t Wo. 1 d r y e r produced a higher t o t a l volume of condensate than Ro. 2 d r y e r . This i s because the sapwood had a much h i g h e r i n i t i a l moisture content than heartwood, and both were d r i e d to a 5 per cent moisture content. Moisture was d r i v e n o f f f a i r l y u n i f o r m l y along the l e n g t h of Mo. 2 d r y e r although an abrupt i n c r e a s e i n volume of condensate occurred at s t a c k no. 4. Stack nos. 1,2, and 6 56 of t h i s d r y e r produced h i g h e r y i e l d s than the corresponding stacks of the Ho. 1 d r y e r . The volume recovered from stack no. 3 i s q u i t e low compared to r e c o v e r i e s of condensate from the adjacent stacks but there i s no apparent reason f o r t h i s occurrence. In the ease of (Mio. 1 d r y e r , moisture was d r i v e n o f f s l o w l y at f i r s t , but the volume of moisture i n c r e a s e d s h a r p l y at stack no. 3 , and reached a maximum at stack no. 4 , before decreasing markedly at the dry end. This t r e n d i s thought to be due to the high i n i t i a l moisture of the wood. T h i s would i n c r e a s e the time r e q u i r e d f o r the wood substance to reach a temperature l e v e l at which the moisture would be r e a d i l y removed. The d r y e r i s so designed t h a t maximum volume of vapour should be r e l e a s e d from stack nos. 2,3, and 4, and t h i s i s confirmed by the r e s u l t s of the i n v e s t i g a t i o n . These s t a c k s are l o c a t e d i n the centre of the zone and d i r e c t l y i n the path of the main stream of a i r which comes o f f from the fans. Twin fans are used to c i r c u l a t e a i r i n these zones, thereby f o r c i n g more of the moisture-laden a i r up the s t a c k s . The f i r s t stack i s l o c a t e d between zones one and two, as comparatively l i t t l e moisture i s r e l e a s e d i n t h i s i n i t i a l area because the wood i s s t i l l r e l a t i v e l y c o l d . The area of the dry e r from zone 5 "bo zone 8 i s equipped w i t h o n l y one stack between two zones, and only one f a n per zone, because most of the moisture has been removed from the veneer befo r e i t reaches these zones. 57 The most important s i n g l e f a c t o r which caused the t o t a l y i e l d of condensate to he much lower than the amount a n t i c i p a t e d p r i o r t o sampling, i s t h a t o n l y one stack was capped at a time, w h i l e a l l of the f i v e others remained open d u r i n g sampling o p e r a t i o n s . There i s no doubt t h a t a s u b s t a n t i a l amount of vapour was d i v e r t e d up adjacent stacks i n the d r y e r , thereby being allowed to escape, because of the p a r t i a l blockage of the stack which was being sampled. As the i n v e s t i g a t i o n was considered to be o n l y a p i l o t study of the condensate and i t s c o n s t i t u e n t s , a l a r g e investment i n the proper equipment which would have been necessary to condense a l l of the vapour from a l l stacks of the d r y e r s i m u l t a n e o u s l y was not f e l t to be e c o n o m i c a l l y j u s t i f i a b l e . T his work,therefore, had to be done i n the best way p o s s i b l e u s i n g the l i m i t e d amount of equipment which was a v a i l a b l e at t h a t time. I t was a l s o understood t h a t such a study should not a d v e r s e l y a f f e c t , or h i n d e r , normal d r y i n g o p e r a t i o n s at the p l a n t . Any measure which would r e s t r i c t the f r e e escape of d r y e r vapour by p h y s i c a l l y b l o c k i n g o f f a l l stack e x i t s except the one being sampled, t h e r e f o r e , was considered to be out of the q u e s t i o n . The p o s i t i o n of the condenser i n r e l a t i o n t o the d i r e c t i o n of escaping vapour was not i d e a l but was necessary f o r p r a c t i c a l reasons such as the condenser's great weight, together w i t h the f a c t t h a t the s t a c k s on Mo. 1 d r y e r were 734 f e e t h i g h . An a d d i t i o n a l , and important drawback to the 58 condensing apparatus, however, was the f a c t t h a t vapour-laden a i r i n the 1 9 - i n c h diameter stack had to he f e d i n t o the condenser through a 4 - i n c h diameter p i p e . This meant t h a t only a p o r t i o n of the a i r which was f o r c e d up the stack a c t u a l l y entered the condenser. In the case of stac k no. 4 on So. 2 d r y e r , a i r v e l o c i t y was i n c r e a s e d from 2000 f e e t per minute i n the stac k , to 3000 f e e t per minute i n the l e a d - i n p i p e , hut the a c t u a l volume of a i r which was t r a n s f e r r e d was reduced from 3940 to 260 cub i c f e e t per minute. I f the a i r was h e a v i l y m o i s t u r e - l a d e n , t h i s f a c t o r would g r e a t l y reduce the amount of c o l l e c t a b l e condensate. A i r v e l o c i t i e s of adjacent s t a c k s were not n o t i c e a b l y a f f e c t e d by the presence of the condensing apparatus. Damper s e t t i n g appears to have l i t t l e or no e f f e c t upon the amount of vapour which was c o l l e c t e d from each stack as evidenced by the f a c t t h a t the l a r g e s t y i e l d from both dr y e r s was obtained from stack no. 4 of Mo. 1 d r y e r , the damper of which was set i n a " c l o s e d " p o s i t i o n . The h a l f - i n c h gap between the edge of the damper and the i n s i d e w a l l o f the st a c k , t o g e ther w i t h the h i g h v e l o c i t i e s at which the a i r i s c i r c u l a t e d i n s i d e the d r y e r i s thought to render the damper comparatively i n e f f e c t i v e as a means of p r o v i d i n g a p h y s i c a l b a r r i e r to the passage of moist a i r out of the d r y e r . V o l a t i l e o i l The p a t t e r n of v o l a t i l e o i l recovery was v e r y s i m i l a r to t h a t of t o t a l condensate recovery. The condensate from 59 a l m o s t e v e r y s t a c k on Ho. 1 d r y e r p r o d u c e d a h i g h e r volume o f v o l a t i l e o i l t h a n t h e c o r r e s p o n d i n g c o n d e n s a t e f r o m Ho. 2 d r y e r , t h e r e b y r e s u l t i n g i n a h i g h e r t o t a l y i e l d o f v o l a t i l e o i l f r o m t h e f o r m e r . V o l a t i l e o i l r e c o v e r y a l s o showed the same t r e n d a l o n g t h e d r y e r as b e f o r e , w i t h t h e maximum y i e l d s o c c u r r i n g a t s t a c k no. 4 o f each d r y e r . I t i s f e l t t h a t the r e a s o n s f o r t h e s e y i e l d p a t t e r n s a r e s i m i l a r t o t h o s e w h i c h have a l r e a d y been s u g g e s t e d f o r t h e r e c o v e r y o f t h e t o t a l c o n d e n s a t e . There a r e s e v e r a l f a c t o r s a f f e c t i n g t h e y i e l d s o f v o l a t i l e o i l w h i c h t h r o w some l i g h t on p o s s i b l e r e a s o n s b o t h f o r t h e low t o t a l r e c o v e r y o f t h e s e v o l a t i l e o i l s w h i c h was e x p e r i e n c e d , and f o r t h e d i f f e r e n c e i n r e c o v e r y between heartwood and sapwood. The l e n g t h o f t i m e t a k e n f o r steam d i s t i l l a t i o n i s o f m a jor i m p o r t a n c e w i t h r e g a r d t o t h e amount o f v o l a t i l e o i l r e c o v e r e d . I n g e n e r a l , t h e l o n g e r t h e p e r i o d o f d i s t i l l a t i o n , t he b e t t e r w i l l be t h e y i e l d o f v o l a t i l e o i l . I n c o m m e r c i a l p r a c t i c e , wood i s steam d i s t i l l e d f o r t h r e e t o f o u r h o u r s b e f o r e i t g i v e s what i s c o n s i d e r e d t o be a s a t i s f a c t o r y y i e l d o f crude wood o i l . V e n e e r w h i c h p a s s e d t h r o u g h t h e d r y e r s , on t h e o t h e r hand, was o n l y s u b j e c t e d t o a steam d i s t i l l a t i o n f o r a p e r i o d o f e i g h t t o e i g h t and a h a l f m i n u t e s i n t h e cease o f ftq. 2 d r y e r , and s e v e n t e e n m i n u t e s i n t h e case o f Mo. 1 d r y e r , t h u s t h e y i e l d s a r e bound t o be c o n s i d e r a b l y l o w e r t h a n t h o s e e x p e r i e n c e d i n c o m m e r c i a l n a v a l s t o r e s p r a c t i c e u s i n g t h e same 60 s p e c i e s . The veneer i n No. 1 d r y e r was steam t r e a t e d f o r twice as long as t h a t i n No. 2 d r y e r and t h i s probably accounts f o r the h i g h e r y i e l d s from the former i n s p i t e of the f a c t t h a t the heartwood i s known to have a l a r g e r r e s i n content than sapwood. Although maximum dr y e r temperatures d i d not g r e a t l y exceed the upper b o i l i n g range of the t u r p e n t i n e f r a c t i o n , the vapour p r e s s u r e s of the v o l a t i l e o i l c o n s t i t u e n t s had a b e n e f i c i a l e f f e c t by l o w e r i n g the b o i l i n g p o i n t of the o i l and water mixture. Examination of vapour pressures of the main v o l a t i l e o i l c o n s t i t u e n t s leads to the c o n c l u s i o n t h a t the temperature w i t h i n the d r y e r i s more than adequate to produce t o t a l d i s t i l l a t i o n of the t u r p e n t i n e f r a c t i o n , and t h a t none of t h i s f r a c t i o n w i l l condense i n s i d e the d r y e r . The same cannot be s a i d f o r the pine o i l f r a c t i o n , which has a h i g h e r b o i l i n g range than t u r p e n t i n e . v a T a r — l i k e d e p o s i t s of a dark brown m a t e r i a l of unknown composition were v i s i b l e along the top of the d r y e r doors i n zones 7 and 8, as w e l l as on the i n s i d e w a l l of s t a c k s 5 and 6 on both d r y e r s . This m a t e r i a l most probably c o n s i s t s of a mixture of pine o i l and wood t a r . One p o s s i b l e reason f o r t h i s d e p o s i t i o n of m a t e r i a l would be the c o o l i n g i n f l u e n c e of the a i r i n the two c o o l i n g s e c t i o n s : s i t u a t e d at the end of the d r y e r . The turbulence of a i r w i t h i n the dryer produces a good mixture of gases, and the d r y e r i s designed to exhaust a l l gases through the r o o f v e n t i l a t o r s t a c k s . 61 The amount of v o l a t i l e o i l recovered from the one-tenth i n c h t h i c k veneer which was d r i e d w i l l be l e s s than the amount c a l c u l a t e d on the b a s i s of y i e l d s from the steam and so l v e n t p rocess, because, i n the l a t t e r case, v o l a t i l e o i l s were e x t r a c t e d from wood which had been broken down i n t o p a r t i c l e form. Wood p a r t i c l e s a l lowed f o r more i n t i m a t e contact w i t h the wood substance by the steam, and the g r e a t e r amount of end g r a i n exposed by the p a r t i c l e s would be b e n e f i c i a l to the amount of e x t r a c t i v e recovered. The method of sampling and the e f f i c i e n c y of the equipment which was used to c o l l e c t the condensate have a l r e a d y been d i s c u s s e d i n r e l a t i o n to t o t a l volume of condensate c o l l e c t e d . The same p o i n t s which were made i n t h i s case a l s o apply to the amount of t o t a l v o l a t i l e o i l m a t e r i a l which was recovered, as t h i s volume i s d i r e c t l y r e l a t e d to the amount of condensate c o l l e c t e d . A f a c t o r which would markedly a f f e c t the v o l a t i l e o i l y i e l d s which were recovered would be the presence of r o s i n i n the e t h e r - s o l u b l e m a t e r i a l . The l a t t e r was assumed to c o n s i s t e n t i r e l y of t u r p e n t i n e and pine o i l . R o s i n lowers the vapour pressure and decreases the o i l - t o - w a t e r r a t i o i n the d i s t i l l a t e . The occurrence of r o s i n would mean a r e d u c t i o n i n the amount of v o l a t i l e o i l which was a c t u a l l y recovered i n the i n v e s t i g a t i o n . This r o s i n , however, would i n c r e a s e the p r o p o r t i o n of the t u r p e n t i n e f r a c t i o n which was a c t u a l l y c o l l e c t e d i n r e l a t i o n to the t o t a l volume of v o l a t i l e o i l which was p r e s e n t , thereby 62 ena b l i n g t h i s f r a c t i o n t o approximate more c l o s e to the t h e o r e t i c a l p r o p o r t i o n of s i x t y - s e v e n per cent which was found i n the case of the v o l a t i l e o i l from Douglas f i r stumpwood. The presence of n o n - v o l a t i l e r o s i n i n the e t h e r - s o l u b l e m a t e r i a l might have been made p o s s i b l e when the s m a l l s o l i d wood p a r t i c l e s which were d r i v e n out of the stacks along w i t h the vapour were washed thoroughly w i t h petroleum ether. I t was noted d u r i n g the q u a n t i t a t i v e a n a l y s i s (stage 1 ) t h a t the ether wash was amber c o l o u r e d and t h a t t h i s c o l o u r became darker as the s o l u t i o n became more concentrated. The b o i l i n g range study on the v o l a t i l e o i l m a t e r i a l produced the r e s u l t s which are recorded i n Appendix D. The c l e a r , pale lemon-ye11ow col o u r e d f r a c t i o n w i t h a b o i l i n g range of 150 to 170 deg. C comprised only 10 per cent and 4 per cent of the t o t a l volumes of v o l a t i l e o i l recovered from Ho'. 1 and No. 2 d r y e r s , r e s p e c t i v e l y . This i s the b o i l i n g range w i t h i n which most of the t u r p e n t i n e w i l l occur. S p e c i f i c g r a v i t y and r e f r a c t i v e index of t h i s f r a c t i o n were measured and gave r e s u l t s which were s l i g h t l y h i gher than the maximum value s f o r wood t u r p e n t i n e suggested by the A.S.T.M. standards ( 1 ) . The volume of t h i s m a t e r i a l was extremely s m a l l compared to t h a t of the t o t a l condensate c o l l e c t e d . I n view of the approximate s e l l i n g p r i c e of t u r p e n t i n e of ninety-two cents per g a l l o n , i t i s q u i t e c l e a r t h a t the amounts, e i t h e r separate or combined, of t h i s m a t e r i a l which were c o l l e c t e d from the d r y e r s were d e f i n i t e l y not of commercial v a l u e . 63 Most of the v o l a t i l e o i l f r a c t i o n c o n s i s t e d of a b l a c k , s l i g h t l y v i s c o u s , o i l y - l o o k i n g substance w i t h a b o i l i n g p o i n t i n excess of 200 deg. C. Summary Crude wood o i l i s steam d i s t i l l e d out of Douglas f i r veneer as i t passes through mechanical d r y e r s . A s m a l l amount of t h i s o i l was c o l l e c t e d from the moisture-laden d r y e r vapours which are f o r c e d out of the r o o f v e n t i l a t o r s t a c k s . More v o l a t i l e o i l v/as c o l l e c t e d from sapwood veneer than from heartwood veneer. A b o i l i n g range d e t e r m i n a t i o n on t h i s o i l showed t h a t over 80 per cent of i t had a b o i l i n g p o i n t i n excess of 200 deg. C, w h i l e o n l y 4 to 10 per cent of i t occurred w i t h i n a b o i l i n g range s i m i l a r to t h a t of wood t u r p e n t i n e ( 1 5 0 to 170 deg The q u a n t i t y of v o l a t i l e o i l which was recovered i n t h i s i n v e s t i g a t i o n was too sm a l l to be considered of commercial val u e . I t i s recommended t h a t no f u r t h e r work of t h i s type should be done on the d r y e r s u n t i l proper standards are determined f o r e v a l u a t i n g both the e f f i c i e n c y of sampling and the q u a l i t y of the e t h e r - s o l u b l e m a t e r i a l c o l l e c t e d . This w i l l r e q u i r e both a q u a n t i t a t i v e and a q u a l i t a t i v e a n a l y s i s of the 64 o r d i n a r y Douglas f i r heartwood and sapwood which i s used to manufacture veneer f o r plywood p r o d u c t i o n . Both analyses should be performed by a q u a l i f i e d chemist and should be conducted under l a b o r a t o r y c o n d i t i o n s so t h a t i d e a l v a l u e s may be determined. I f the r e s u l t s of the analyses are f a v o u r a b l e , an examination of the market p o t e n t i a l of those v o l a t i l e o i l components which w i l l be of commercial importance should then be undertaken. Only i f t h i s market a n a l y s i s work a l s o proves encouraging should f u r t h e r sampling work on the d r y e r s be c a r r i e d out. B e t t e r condensing equipment w i l l be necessary i f more e f f i c i e n t sampling i s d e s i r e d . With regard to sampling, i t appears t h a t any a d d i t i o n a l work on the d r y e r s need o n l y be done on stack numbers 2, 3, and 4, although some method must be found at the same time t o prevent the escape of excessive amounts of vapour from the other s t a c k s , without a d v e r s e l y a f f e c t i n g the normal c o n d i t i o n s of d r y i n g w i t h i n the veneer d r y e r . 65 BIBLIOGRAPHY 1. Amer. Soc. f o r T e s t i n g M a t e r i a l s . 1 9 3 6 . Standard s p e c i f i c a t i o n s f o r s p i r i t s of t u r p e n t i n e . A.S.T.M. Standards, P a r t I I . D e s i g n a t i o n D 13-34. pp. 742-743. 2. . 1949. Standard d e f i n i t i o n s of terms r e l a t i n g to n a v a l s t o r e s and r e l a t e d products. A.S.T.M. Standards, P a r t IV. D e s i g n a t i o n D 804-48. pp. 5 7 2 - 5 7 6 . 3 . 1 9 4 9 . Standard method of sampling and t e s t i n g t u r p e n t i n e . A.S.T.M. Standards, P a r t IV. 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The sap or moisture i n wood. U.S. Dent, of A g r i c . For. Serv. For. Prod. Lab. Rept. No. R 768. 4pp^ 67 2 7 . P r i e s t , G.H. 192?'. Naval s t o r e s : P r o d u c t i o n , Consumption and D i s t r i b u t i o n . U.S. Dept. of Commerce. Trade I n f . B u l l . No. 454. 3 9 p p . 28. H i t t e r , G.J. and L.C. F l e c k . 1926. Chemistry of wood, P a r t V I I I , f u r t h e r s t u d i e s of sapwood and heartwood. Ind. and Eng. Chem. 18(6 ) 5 7 6 - 5 7 7 -29. Schorger, A.W. 1917- O l e o r e s i n i n Douglas f i r . Jour. Amer. Chem. Soc. 32(5):1040-1044. 3 0 . Schwartz, H. and C. Greaves. 1944. P r o d u c t i o n of pine t a r by d e s t r u c t i v e d i s t i l l a t i o n of Canadian softwoods. Canada. For. Prod. Lab. Ottawa. Mimeo. 136. 14pp. 3 1 . V e i t c h , F.P. and V.E. G r o t l i s c h . 1 9 2 0 . Turpentine: i t s sources, p r o p e r t i e s , uses, t r a n s p o r t a t i o n and marketing. U.S. Dept. of A g r i c . For. Serv. B u l l . 898. 1 0 p p . 3 2 . Wise, L.E. and E.C. Jahn. 1 9 5 2 . Wood Chemistry, V o l s . 1 and 2 . Reinhold P u b l i s h i n g Corp., New York. 1343pp. A P P E N D I C E S Appendix A Sim p l i f i e d Plan of a Veneer Dryer (not to scale) Plan view l£nfER»TV«.e CHARTS V E N E E R " N k A V E L C O I I S 14 C0«kS 14 S T A C K FEET> S E C T I O N | Z o M E I | 8 12.' sV-»T« Jo' 13 117 S-t 7 » Side view • • • • • 0 0 0 0 O \ / O O O O End view T>oo»s HSATilts C * U A C0IC4 A l 4 > ROILS T»OOAS Appendix B Dryer Temperatures No. 1 Dryer Temperature J°cl Stack no. Zone no. Min. Max. Average 1 1 174 182 175 1 and 2 2 187 195 192 3 3 189 200 194 4 4 189 195 192 5 : 5 195 204 199 5 6 197 204 201 6 7 196 202 200 6 8 183 202 185 No. 2 Dryer Temperature Stack no. Zone no. Min. Max. Average 1 1 162 177 168 1 and 2 2 182 193 185 3 3 177 191 183 4 4 190 200 192 5 5 194 203 197 5 6 192 199 195 6 7 188 192 190 6 8 189 197 192 Temperature Reduction Due to Moisture Pick-rup and R a d i a t i o n Losses Stack Vapour Temperature (°C) Dryer (°C) . Temperature Top of Stack Damper L e v e l 1 158 158 167 2 154 154 183 3 159 159 180 4 178 178 191 5 1 159 164 194 6 57 82 189 70 Appendix G Stack A i r Velocity-No. 1 Dryer Stack Zone Damper S e t t i n g V e l o c i t y ( f t . per min.) 1 1 and 2 Quarter open 550 2 2 Quarter open 1400 3 3 Quarter open 700 4 4 Closed 1350 5 5 and 6 Closed 700 6 7 and 8 Closed 350 No. 2 Dryer Stack Zone Damper S e t t i n g V e l o c i t y ( f t . per min.) 1 1 and 2 Quarter Open 450 2 2 Quarter open 550 3 3 Quarter open 1400 4 4 H a l f open 2000 5 5 and 6. H a l f open 400 6 7 and 8 Closed 300 Appendix D B o i l i n g P o i n t Range Determination Temperature ( S O Percentage of Sample No. 1 Dryer ,No. 2 Dryer 75 t o 150 2 11 150 t o 170 10 4 170 to 200 4 4 above 200 84 81 Note: R e s u l t s f o r No. 1 d r y e r are "based on a sample of 17.8 ml. R e s u l t s f o r No. 2 d r y e r are based on a 0.9 m l . sample ( i n i t i a l B.P. of 78 deg. C). Examination of 150 deg. C to 170 deg. C F r a c t i o n S p e c i f i c g r a v i t y at 20 deg. C = 0.877 R e f r a c t i v e index at 20 deg. C = 1.4788 72 Appendix E Q u a n t i t a t i v e A n a l y s i s R e s u l t s f o r T o t a l Condensate No. 1 Dryer (a) (b) ( O Cd) (e) Wt. of suspended V o l a t i l e o i l s Vent. No. of Wt. o f T o t . v o l . s o l i d s i n ( E t h e r - s o l u b l e s ) stack hours s o l i d s c o l l e c t e d 100 ml. c o l l e c - (gm-) (ml.) HpO S o l - v o l . t i n g uble s(gm.) (ml.) 1 22 1 .91 4330 0.26 0 . 8 2 23 1 . 10 5920 0.36 3 . 0 3 26 3 . 5 0 19310 0.30 7 . 2 4 16 5 . 4 4 19530 0.08 6.2 5 23 1.46 4840 0.13 1 . 5 6 23 0 . 3 7 330 0.13 1 . 4 T o t a l 133 1 3 . 7 9 54260 2 0 . 1 No. 2 Dryer (a) (b) (c) (d) (e) Wt. of suspended V o l a t i l e o i l s Vent. No. of Wt. of T o t . v o l . s o l i d s i n ( E t h e r - s o l u b l e s ) stack hours s o l i d s c o l l e c t e d 100 ml. c o l l e c - (gm-) (ml.) H2O s o l - v o l . t i n g u b l es (gm.) (ml.) 1 24 7 - 8 7 7640 0 . 0 9 1 .7 2 4 9 5-63 17870 0.06 4.6 3 24 5 . 1 7 5810 0 . 1 3 5 . 0 4 18 3-78 10810 0 . 0 7 6.0 5 23 3 . 2 2 4340 0.10 1 . 4 • 6 64 0.35 4960 0.10 2 . 7 T o t a l 202 26.02 51430 2 1 . 4 Appendix A Si m p l i f i e d Plan of a Veneer Dryer (not to scale) Plan view fEr>fERMVI>.E CHARTS Side view • • • • • o o o o o ^ t o o o o End view 3>O0RS c e i L S COILS A«4» ROLLS 1>OoRs 

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