Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The correlation of true boiling point and equilibrium flash vaporization curves for some Canadian crude… Hayduk, Walter 1955

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1956_A7 H2 C6.pdf [ 2.87MB ]
Metadata
JSON: 831-1.0059288.json
JSON-LD: 831-1.0059288-ld.json
RDF/XML (Pretty): 831-1.0059288-rdf.xml
RDF/JSON: 831-1.0059288-rdf.json
Turtle: 831-1.0059288-turtle.txt
N-Triples: 831-1.0059288-rdf-ntriples.txt
Original Record: 831-1.0059288-source.json
Full Text
831-1.0059288-fulltext.txt
Citation
831-1.0059288.ris

Full Text

THE CORRELATION OF TRUE BOILING POINT AND EQUILIBRIUM FLASH VAPORIZATION CURVES FOR SOME CANADIAN CRUDE OILS by WALTER HAYDUK A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n the Department of Chemical Engineering We accept t h i s t h e s i s as conforming t o the standard r e q u i r e d from candidates f o r the degree of MASTER OF APPLIED SCIENCE Members of the Department of Chemical Engineering THE UNIVERSITY OF BRITISH COLUMBIA October, 1955. ABSTRACT An Ofchmer r e c i r c u l a t i n g s t i l l and a standard packed column f r a c t i o n a t i n g u n i t were us«d i n d e t e r -mining the e q u i l i b r i u m f l a s h v a p o r i z a t i o n and t r u e b o i l i n g p o i n t curves r e s p e c t i v e l y , f o r e i g h t samples of crude o i l s from producing o i l - f i e l d s i n A l b e r t a . The EFV curves, at 10 mm. absolute pressure were a l s o obtained f o r these samples. Determinations at atmospheric pressure were used f o r modifying Okamoto and Van Winkle's c o r r e l -a t i o n , which a l l o w s the p r e d i c t i o n of the EFV curves from the TBP curves, f o r a p p l i c a t i o n t o crude o i l s . The c o r r e l a t i o n r e l a t e s the 50 percent p o i n t s and the slopes of the two curves. I n s p i t e of i t s s i m p l -i c i t y , i t r e s u l t s i n p r e d i c t e d curves of good accuracy. I t i s b e l i e v e d t h a t t h i s method i s s u i t a b l e f o r a l a r g e number of crudes and can give dependable phase e q u i l i b r i u m data. ACKNOWLEDGEMENTS Ap p r e c i a t i o n i s expressed f o r the suggestions and guidance given by Dr. L. W. Sherailt under whose super-v i s i o n t h i s research was performed. Acknowledgement i s a l s o made t o the Im p e r i a l O i l Company of Canada and the Standard O i l Company of Canada who sup p l i e d the samples. TABLE OF CONTENTS Page I , INTRODUCTION 1 # I I . PREVIOUS CORRELATIONS 3. 5. I I I . APPARATUS (a) TBP S t i l l (b) EFV S t i l l (c) Temperature Measurement IV. SAMPLES AND MATERIALS X 6 # V. PROCEDURE 20. (a) TBP S t i l l (b) EFV S t i l l (c) C a l i b r a t i o n of TBP column VI. RESULTS 29. •VII. DISCUSSION OF RESULTS 5 6 # V I I I . BIBLIOGRAPHY 6 1 # TABLES Page Table I Numerical Data f o r TBP and EFT Experimental P o i n t s 51 Table I I Numerical Data f o r TBP and EFV C o r r e l a t i o n s 55 ILLUSTRATIONS 1. Diagram of TBP S t i l l , F i g . 1. 6 2. Diagram of EFV S t i l l , F i g . 2. 10 3. C a l i b r a t i o n curve f o r thermometers, F i g . 3. 14 4. Cox ch a r t , F i g . 4. 23 5. McCabe-Thiele Method f o r TBP column E f f i c i e n c y , F i g . 5. 28 6. C o r r e l a t i o n of TBP and EFV 50 percent points., F i g . 6. 30 7. C o r r e l a t i o n of TBP and EFV s l o p e s , F i g . 7. 31 8. Atmospheric and 10 mm. EFV curves, F i g . 8a-8h. 32 9. Phase Diagrams f o r crude o i l samples, F i g . 9. 41 10. Atmospheric TBP and EFV curves, F i g . lOa-lOh. 43 1. I . INTRODUCTION Such operations as the v a p o r i z a t i o n and condensation of hydrocarbon mixtures are bas i c i n the production and r e f i n i n g of petroleum. I t i s o f t e n necessary t o p r e d i c t vapor-l i q u i d phase e q u i l i b r i u m c o n d i t i o n s i n process design c a l c u t l a t i o n s and i n a n a l y z i n g commercial operations. The a b i l i t y to p r e d i c t a c c u r a t e l y the product d i s t r i b u t i o n of a new crude mixture, or the operating c o n d i t i o n s t o gi v e d e s i r e d y i e l d s of c e r t a i n f r a c t i o n s , i s of prime economic importance. For the s o l u t i o n of problems concerned w i t h the phase e q u i l i b r i a of complex hydrocarbon mixtures, e m p i r i c a l methods based on the common l a b o r a t o r y , d i s t i l l a t i o n s , m u s t s t i l l be used. Petroleum d i s t i l l a t i o n processes i m v a r i a b l y e n t a i l the preheating of the stock or crude w i t h subsequent f l a s h i n g i n the d i s t i l l a t i o n column. C a l c u l a t i o n s f o r the c o n d i t i o n s of temperature and pressure r e q u i r e d t o give a p a r t i c u l a r residuum are s i m p l i f i e d by the use of e q u i l i b r i u m flash£ vapor-i z a t i o n (EFV) curves. These c o n s i s t of p l o t s showing i s o b a r i c curves of percent vaporized versus the v a p o r - l i q u i d e q u i l i b r i u m temperature. The small l a b o r a t o r y EFV s t i l l designed by Othmer (15) has proven t o be s u c c e s s f u l f o r o b t a i n i n g EFV curves at subatmospheric pressures. Since subatmospheric pressures r are general i n petroleum r e f i n i n g , the EFV curves are w i d e l y a p p l i c a b l e . Because these s t i l l s are not as yfct standard l a b o r a t o r y equipment and because of the experiemental d i f f i c u l t i e s i n v o l v e d , EFV curves are u s u a l l y p r e d i c t e d from the more common true b o i l i n g point (TBP) and A.S.T.M. d i s t i l l a t i o n curves. C o r r e l a t i o n s f o r p r e d i c t i n g EFV curves which can be ap p l i e d t o petroleum f r a c t i o n s are u n s a t i s f a c t o r y f o r crudes. A s u i t a b l e c o r r e l a t i o n f o r crudes was the subject of t h i s i n v e s t i g a t i o n . Because the A.S.T.M. d i s t i l l a t i o n i s not very repr o d u c i b l e and i s d i f f i c u l t t o complete f o r crudes, the TBP d i s t i l l a t i o n was chosen as being the more s u i t a b l e f o r c o r r e l a t i n g purposes. 3 . I I . PREVIOUS CORRELATIONS Two t y p e s of e m p i r i c a l c o r r e l a t i o n s a p p l y i n g g e n e r a l l y t o petroleum f r a c t i o n s are a v a i l a b l e i n the l i t e r a t u r e f o r p r e d i c t i n g the EFV curve at atmospheric pressure. One type uses the i n t e r s e c t i o n p o i n t and the slopes of the f l a s h and A.S.T.M. or TBP curves, and the other uses the 50 percent b o i l i n g p o i n t s and slopes. I n the method proposed by Piroomov and Beiswenger (17) the f l a s h curve was assumed t o be a s t r a i g h t l i n e and was l o c a t e d by e s t i m a t i n g the p o i n t of i n t e r s e c t i o n and i t s slope from the smoothed A.S.T.M. or TBP d i s t i l l a t i o n s . I n the method proposed by Nelson and Souders (11) and mod i f i e d by . Katz and Brown (9) the EFV curve was a l s o assumed t o be a s t r a i g h t l i n e and was p r e d i c t e d by e s t i m a t i n g i t s 50 percent p o i n t and slope from the 50 percent p o i n t and 10-70 percent slope of the A.S.T.M. or TBP d i s t i l l a t i o n s . Experiment aLL EFV data i n d i c a t e t h a t the l i n e s are not a c t u a l l y s t r a i g h t although the curvature f o r a l a r g e p o r t i o n of the curve i s s l i g h t ( 1 6 ) . I n the method presented by Packie (16) and r e v i s e d by Edmister and P o l l o c k (4) t h i s departure from a s t r a i g h t l i n e was taken i n t o c o n s i d e r a t i o n . None of the e x i s t i n g methods of . c o r r e l a t i o n are constructed to apply s p e c i f i c a l l y f o r crudes. The Edmister and P o l l o c k c o r r e l a t i o n , f o r example, uses the TBP slopes as parameters on a p l o t of TBP 50 percent versus the d i f f e r e n c e i n TBP and EFV 50 percent p o i n t s . The s l o p e s , however, have too s m a l l a range t o account f o r the steep slopes of TBP curves 4. f o r crudes. As a r e s u l t a s i m p l i f i e d c o r r e l a t i o n by Okamoto and Van Winkle (14)^which shows general r e l a t i o n s h i p s between TBP and EFV curves, has been chosen as a b a s i s f o r the present c o r r e l a t i o n . In t h i s c o r r e l a t i o n the' EFV 50 percent p o i n t i s determined from the TBP 50 percent points, and the 10-70 percent s l o p e i f r o m the TBP. 10-70 percent s l o p e . The values f o r the crude o i l s are compared d i r e c t l y w i t h the c o r r e l a t i o n of Okamoto and Van Winkle. 5 I I I . APPARATUS (a) True B o i l i n g P o i n t S t i l l The TBP apparatus c o n s i s t s of an a l l - g l a s s a n a l y t i c a l d i s t i l l a t i o n u n i t w i t h an e f f i c i e n t f r a c t i o n a t i n g column s u i t a b l e f o r crude e v a l u a t i o n . Accessories i n c l u d e a l i q u i d - d i v i d i n g s t i l l - h e a d f o r convenient r e f l u x c o n t r o l , a vacuum u n i t w i t h a pressure c o n t r o l l e r and d r y - i c e t r a p , a mercury manometer, and a manifold p e r m i t t i n g separate evacuation of the d i s t i l l a t e r e c e i v e r during vacuum ope r a t i o n . F i g u r e 1 shows the arrangement of the apparatus. A g l a s - c o l heater provides the necessary heat input to the s t i l l - p o t ; f o r reducing the l a r g e heat l o s s at the h i g h temperatures used, a u x i l i a r y ribbon heaters covered w i t h i n s u l a t i o n enclose the column and s t i l l - h e a d . The u n i t i s compact and simple i n o p e r a t i o n , designed t o operate w i t h a minimum amount of a t t e n t i o n . The column i s a standard type 1-inch s i l v e r e d vacuum-jacketed column packed t o height of 22 inches w i t h 1/8 i n c h g l a s s h e l i c e s . Twelve expansion bellows along the outer j a c k e t permit the necessary expansion f o r the h i g h temperatures encountered i n crude d i s t i l l a t i o n . The performance of the column when c a l c u l a t e d by the McCabie and T h i e l e method (10) using a benzene-carbon t e t r a c h l o r i d e t e s t mixture, i s 11.4 t h e o r e t i c a l p l a t e s . This performance corresponds t o o p e r a t i o n at atmospheric pressure, at t o t a l r e f l u x , and a d i s t i l l a t i o n r a t e of about 1500 ml. REFLUX TIMER V s " POTENTIOMETER 7. per hour, the r a t e normally used. The column i n conjunction w i t h the r e f l u x c o n t r o l s t i l l - h e a d has an a v a i l a b l e feed c a p a c i t y considerably higher than that used i n these d e t e r -minations; however, f o r convenience, r e l a t i v e l y s m a l l samples, (2 l i t r e s ) were d i s t i l l e d . At 10 mm. pressure no s i g n i f i c a n t d i f f e r e n c e i n column o p e r a t i o n was obsejrved. In a l l respects the column operated s u c c e s s f u l l y . An automatic l i q u i d - d i v i d i n g s t i l l - h e a d (manu-f a c t u r e d by the Glass Engineering L a b o r a t o r i e s , San C a r l o s , C a l i f o r n i a ) (3) a c t i v a t e d by a s o l e n o i d , along w i t h a water-cooled condenser, provides any d e s i r e d r e f l u x r a t i o . The s t i l l - h e a d i s so constructed that the vapor stream r i s i n g from the column f l o w s past a ground-joint p a r t i a l - i m m e r s i o n thermometer, then d i r e c t l y to the condenser. The condensate flows down through the s t i l l - h e a d by a d i f f e r e n t route, passing through a small t i p p i n g f u nnel which normally d i r e c t s the l i q u i d stream t o the centre of the column packing. Contained i n the t i p p i n g f u n n e l i s a piece of s o f t i r o n which can be a t t r a c t e d by a s o l e n o i d outside the s t i l l - h e a d . When so a t t r a c t e d the funnel d i r e c t s the l i q u i d stream through a vapor t r a p t o the product r e c e i v e r . The s o l e n o i d i s a c t i v a t e d by an e l e c t r o n i c t i mer which s u p p l i e s power f o r three seconds at a time. R e f l u x c o n t r o l i s e f f e c t e d by changing the on-off time r a t i o of the t i m e r and assuming t h a t t h i s corresponds t o the l i q u i d r e f l u x r a t i o obtained. Tests have i n d i c a t e d t h a t the r e f l u x r a t i o - c o n t r o l l e r g i v e s a somewhat hi g h e r r e f l u x 8. r a t i o than i n d i c a t e d by the timer (3); however, t h i s does not s i g n i f i c a n t l y e f f e c t the operation of the column. The vacuum u n i t i n c l u d e d an o i l - f i l l e d fore-pump-type, vacuum pump, a surge tank, a Cartesian-type manostat, and a d r y - i c e t r a p connected i n s e r i e s . The surge tank was equipped w i t h a needle valve t o a l l o w an approximate pressure adjustment t o a value somewhat lower than r e q u i r e d i n the u n i t ; the pressure was maintained p r e c i s e l y by the manostat. The d r y - i c e t r a p was used i n the main evacuating l i n e to prevent the escape of l i g h t f r a c t i o n s . The pressure i n the u n i t was measured by a mercury manometer connected to the vacuum l i n e from the condenser. 9. ( b ) E q u l t i b r i u m F l a s h : V a p o r i z a t i o n S t i l l The most s u c c e s s f u l l a b o r a t o r y v a p o r - l i q u i d e q u i l i b r i u m s t i l l s almost i n v a r i a b l y employ condensate r e -c i r c u l a t i o n . The vapor i n e q u i l i b r i u m w i t h the b o i l i n g l i q u i d i s passed i n t o a condenser, and the condensate i s c o l l e c t e d i n a r e s e r v o i r from which i t i s r e c i r c u l a t e d back i n t o the b o i l i n g l i q u i d . When the e n t i r e s t i l l has reached a steady s t a t e , the s a t u r a t e d vapor r i s i n g from the b o i l i n g l i q u i d i s of the same composition as the r e c i r c u l a t i n g condensate, and i s at the same temperature as the b o i l i n g l i q u i d . The v a p o r - l i q u i d s t i l l designed by Othmer.^(l$)) f o r the determination of EFV curves of crudes and petroleum f r a c t i o n s e n t a i l s two b a s i c m o d i f i c a t i o n s : a method of v a r y i n g the volume of condensate h e l d up i n the r e s e r v o i r , and of a c c u r a t e l y determining t h i s volume without i n t e r r u p t i n g the operation of the s t i l l . A graduated r e s e r v o i r w i t h a c a p i l l a r y stopcock i n the r e c y c l e l i n e e f f e c t i v e l y solve these problems. The Othmer s t i l l along w i t h a u x i l i a r y equip-ment i n c l u d i n g a vacuum pump, surge tank, d r y - i c e t r a p and manometer, i s shown i n F i g u r e 2. The; s t i l l c o n s i s t s of a complete.pyrex g l a s s u n i t : a 500 ml. s t i l l - p o t , vapor-arm, primary condenser, graduated r e c e i v e r , and r e f l u x l i n e . Nichrome r e s i s t a n c e heaters provide e x t e r n a l h e a t i n g t o the s t i l l - p o t , vapor-arm, and r e f l u x l i n e ; these s e c t i o n s are a l s o i n s u l a t e d w i t h asbestos l a g g i n g coated w i t h aluminum p a i n t to prevent excess heat l o s s by r a d i a t i o n . 4 11. An i n t e r n a l nichrome r e s i s t a n c e heater e f f e c t s smooth b o i l i n g , without bumping of or superheating of even s m a l l l i q u i d volumes. The bottom s e c t i o n of the s t i l l - p o t i s f a b r i c a t e d w i t h a s m a l l e r bubble so that the depth of l i q u i d i s s u f f i c i e n t f o r h e a t i n g and a c c u r a t e l y measuring the temperature when most of the change i s i n the condensate r e s e r v o i r . The vapor-arm i s of a s i z e determined by two requirements: t h a t the pressure drop of the vapor passing to the r e s e r v o i r should be n e g l i g i b l e , and that the t o t a l volume of the vapor i n the f r e e space of the s t i l l - p o t and vapor-arm should be s m a l l enough t o introduce n e g l i g i b l e e r r o r i n the l i q u i d volume measurement. The pressure drop across the vapor-arm depends on the vapor-i z a t i o n r a t e which, at low pressures (10 mm), can be c o n s i d e r a b l e ; f o r t h i s reason a uniform slow d i s t i l l a t i o n r a t e i s i m p e r a t i v e . The e r r o r introduced by n e g l e c t i n g the amount of vapor i n the s t i l l i n measuring the condensate volume corresponds t o l e s s than 5 n i l . of condensate during adverse c o n d i t i o n s ( 1 5 ) . A c o r r e c t i o n can be a p p l i e d i n very p r e c i s e work; however, t h i s i s u s u a l l y not necessary since i t i s d the order of accuracy f o r reading the volume i n the r e s e r v o i r . At reduced pressures, t h i s e r r o r g r e a t l y decreases i n magnitude. The condenser i s constructed i n two p a r t s f o r handling crudes or heavy f r a c t i o n s . The primary condenser can be operated at a temperature j u s t s u f f i c i e n t t o condense the h i g h e r b o i l i n g p o r t i o n of the vapors and s t i l l a l l o w the condensate t o f l o w f r e e l y down the w a l l s without f r e e z i n g out the waxy . m a t e r i a l . The more v o l a t i l e p o r t i o n i s condensed i n the secondary condenser cooled t o a lower temperature. Since a 'small p o r t i o n of the crude o i l s c o n s i s t s of a h i g h l y v o l a t i l e f r a c t i o n , the d r y - i c e t r a p serves as an a u x i l i a r y condenser; during 10 mm. pressure operation w i t h l i g h t crudes as much as 25 ml. of condensate was c o n s i s t e n t l y c o l l e c t e d i n the t r a p . The volume was c a r e f u l l y measured and added to t h a t i n the r e s e r v o i r ; i t was i m p r a c t i c a l t o attempt t o keep t h i s v o l a t i l e f r a c t i o n i n the r e s e r v o i r because i t b o i l e d at the r e s e r v o i r temperature. The pressure i n the u n i t was measured by an absolute manometer and maintained at a constant value by a C a r t e s i a n -type manostat. (c) Temperature Measurement Three devices are commonly used f o r measuring temperatures, the mercury thermometer, thermocouple, and r e s i s t a n c e thermometer. The mercury thermometer i s a v a i l a b l e f o r use e i t h e r as a total-immersion o r a p a r t i a l - i m m e r s i o n thermometer. I n both cases s i m i l a r problems are presented i f very p r e c i s e temperature measurement of the vapor phase i n a v a p o r - l i q u i d e q u i l i b r i u m determination i s r e q u i r e d . I t i s d i f f i c u l t t o construct a s t i l l - h e a d or s t i l l - p o t t h a t a l l o w s adequate c i r c u l a t i o n of the vapor or l i q u i d around the s e c t i o n of the thermometer s p e c i f i e d f o r immersion. The p a r t i a l -immersion thermometer u s u a l l y creates a vapor pocket where 13. i t enters the s t i l l - h e a d ; the emergent stem i s a l s o exposed t o v a r i a b l e temperatures. These problems l i m i t the use of mercury thermometers i n very p r e c i s e work. Both the thermocouple and r e s i s t a n c e thermometer can given h i g h l y accurate temperature measurements. Although the r e s i s t a n c e thermometer o f f e r s the gr e a t e s t accuracy as w e l l as maximum r e l i a b i l i t y and r e p r o d u c i b i l i t y , the thermocouple i s of more general use because i t i s l e s s bulky, has l i t t l e temperature l a g , and r e q u i r e s the use of only a potentiometer. The r e s i s t a n c e thermometer i s e s p e c i a l l y s u i t a b l e f o r c a l i b r a t i n g purposes. In both the TBP and EFV determinations p a r t i a l -immersion thermometers were used to measure the v a p o r - l i q u i d e q u i l i b r i u m temperatures. The accuracy d e s i r e d , * 1.0°F, i n s p i t e of the inherent p o s s i b l e e r r o r , was r e a d i l y obtained as shown when these thermometers were c a l i b r a t e d against the N a t i o n a l Bureau of Standards No. 169314; r e s i s t a n c e thermometer. The c a l i b r a t i o n curves appear i n F i g u r e 3. The thermometers were used i n preference t o thermocouples because the o r i g i n a l designs of both u n i t s i n c l u d e d ground-joint p a r t i a l - i m m e r s i o n thermometers. These were convenient- because of ease i n reading throughout the whole range of temperatures encountered. I n the EFV apparatus a s p e c i a l advantage of the use of a p a r t i a l - i m m e r s i o n thermometer was that the l i q u i d temper-ature i n the s t i l l could be watched and checked r e a d i l y w h i l e adjustments were made to the hea t e r s . Other temperatures could be measured by thermocouples l o c a t e d at v a r i o u s p o i n t s CALIBRATION OF THERMOMETERS 15. of the s t i l l - p o t , vapor-arm and r e c y c l e l i n e at the g l a s s -i n s u l a t i o n i n t e r f a c e . By means of a m u l t i p l e - s w i t c h and Leeds and Northrup type K potentiometer, the temperature at any point r e q u i r e d could be obtained. An a u x i l i a r y thermometer was placed i n the vapor-arm thermometer w e l l by which a check on the extent of superheating could be made. The TBP u n i t r e q u i r e d a p a r t i a l - i m m e r s i o n thermometer s p e c i f i e d t o f i t the s t i l l - h e a d ; the s t i l l - h e a d i s designed to reduce the thermometer e r r o r due to poor vapor c i r c u l a t i o n . The thermometer i s centred i n the vapor-stream a l l o w i n g a maximum amount of contact. Another thermometer was used t o give an approximate i n d i c a t i o n of the temperature of the ribbon heater surrounding the s t i l l - h e a d . The crude charge temperature was measured by means of an iron-constantan thermo-couple and potentiometer. This thermocouple was used only as an approximate check f o r keeping the charge temperature below 650°F and, t h e r e f o r e , was not c a l i b r a t e d . 16. IV. SAMPLES AND MATERIALS (a) Crude O i l Samples Eight samples of A l b e r t a crude o i l were analyzed. Assurance was given t h a t the samples were drawn t o giv e r e p r e s e n t a t i v e composite samples of the o i l - f i e l d or p i p e l i n e . Storage i n a c o o l place avoided excessive vapor l o s s . Relevant i n f o r mation about the samples i s l i s t e d below: API G r a v i t y 1. Pembina crude - r e p r e s e n t a t i v e sample from Pembina P i p e l i n e stream d e l -i v e r e d i n 10 g a l l o n drum August 16, 1955, by I m p e r i a l O i l Company L i m i t e d . 38.0 2. Wizard Lake crude - r e p r e s e n t a t i v e sample from b a t t e r y r e c e i v i n g crude from s e v e r a l producing w e l l s i n the Wizard Lake f i e l d d e l i v e r e d i n 10 g a l l o n drum August 16, 1955, by I m p e r i a l O i l Company L i m i t e d . 37.5 3. Leduc-Woodbend crude - r e p r e s e n t a t i v e sample from I m p e r i a l Pipe Li n e Leduc gathe r i n g system d e l i v e r e d i n 10 g a l l o n drum August 16, 1955, by I m p e r i a l O i l Company L i m i t e d . 40.1 API G r a v i t y 4. Texaco P i p e l i n e crude - r e p r e s e n t a t i v e sample of crude mixture from Texaco Pipe L i n e b a t t e r y as Received through Trans-Mountain Pipe L i n e , d e l i v e r e d i n 5 g a l l o n can J u l y , 1955, by Standard O i l Company L i m i t e d . 40.6 5. Redwater crude - r e p r e s e n t a t i v e sample of crude from I m p e r i a l Pipe Line Redwater system as re c e i v e d through Trans Mountain P i p e l i n e , d e l i v e r e d i n 5 g a l l o n can J u l y , 1955, hy Standard O i l Company L i m i t e d . 35»5 6« S t e t t l e r crude - r e p r e s e n t a t i v e sample of crude from S t e t t l e r f i e l d d e l i v e r e d i n 5 g a l l o n can i n 1952, by I m p e r i a l O i l Company L i m i t e d . 28.8 7. Joseph Lake crude - r e p r e s e n t a t i v e sample of crude from Joseph Lake f i e l d d e l i v e r e d i n 5 g a l l o n can i n 1952 by I m p e r i a l O i l Company L i m i t e d . 37*3 8. Golden Spike crude - r e p r e s e n t a t i v e sample of crude from Golden Spike f i e l d d e l i v e r e d i n 5 g a l l o n can i n 1952 by I m p e r i a l O i l Company L i m i t e d . 38.9 Since both the TBP and EFV curves were t o be determined on a volume percent b a s i s , accurate measurement of the volume of crude charge t o the s t i l l s was r e q u i r e d . The 18. charge p o r t i o n s to the TBP and EFV s t i l l s were 2000 ml. and 500 ml., r e s p e c t i v e l y . Since the samples were at an approx-imate temperature of 60°F and not very v i s c o u s , they were poured d i r e c t l y i n t o a graduated c y l i n d e r of appropriate s i z e t o a l e v e l somewhat higher than the volume to be d e l i v e r e d . When the graduate was emptied and o i l allowed t o d r a i n t o the bott©m'f the remaining volume could be estimated. By p r a c t i c e the volume of charge r e q u i r e d could be r e a d i l y obtained by t h i s method. (b) Benzene and Carbon T e t r a c h l o r i d e 'A. t e s t mixture of benzene-carbon t e t r a c h l o r i d e was used t o determine the e f f i c i e n c y of the TBP d i s t i l l a t i o n column. P u r i f i c a t i o n was r e q u i r e d t o o b t a i n a r e f r a c t i v e index f o r the benzene which compared favourably w i t h published r e s u l t s . A commercially pure grade of benzene was s u p p l i e d by the N i c h o l s Chemical Company. Thiophene was removed by shaking a mixture of benzene and concentrated s u l f u r i c a c i d i n a l a r g e s e p a r a t i n g f u n n e l . The operation was repeated w i t h new p o r t i o n s of a c i d u n t i l no thiophene d i s c o l o r a t i o n appeared. The concentrated a c i d would a l s o remove most of the water i f i t was present. A f t e r c a r e f u l s e p a r a t i o n of the a c i d l a y e r the thiophene-free benzene was placed i n a clean 2 1 . d i s t i l l a t i o n f l a s k over sodium ribbon and allowed t o stand f o r a day. The top of the f l a s k was closed w i t h a d r y i n g f u n n e l of calcium oxide a l l o w i n g f r e e e v o l u t i o n of hydrogen. 19, D i s t i l l a t i o n f o r f i n a l p u r i f i c a t i o n was performed i n a packed column of 14 equivalent plates previously used f o r p u r i f i c a t i o n purposes (19). The column was c a r e f u l l y cleaned with acetone and dried. D i s t i l l a t i o n of the benzene was carr i e d out over sodium at a r e f l u x r a t i o of 30:1. The i n i t i a l 200 ml. portion was discarded a f t e r which about 1 1. of pure benzene of b o i l i n g point 80.4 °C was obtained f o r t e s t i n g purposes. The carbon tetra c h l o r i d e obtained from the Baker and Adamson Company was p u r i f i e d by d i s t i l l a t i o n only. D i s t i l l a t i o n at a ref l u x r a t i o of 30:1 gave carbon tetra c h l o r i d e of a re f r a c t i v e index that checked favourably with that given i n the l i t e r a t u r e . Refractive indices obtained at 25°C were 1.4572 and 1.4980 f o r carbon t e t r a chloride and benzene, respectively, compared with l i t e r a t u r e values of 1.45734 and 1.49794 (8). 20. PROCEDURE (a) TBP S t i l l The o p e r a t i o n of the TBP s t i l l was e s s e n t i a l l y the same as t h a t of any l a b o r a t o r y f r a c t i o n a t i n g u n i t . A b a s i c d i f f e r e n c e , however, was t h a t two pressures were used d u r i n g the d i s t i l l a t i o n of crudes: atmospheric d i s t i l l a t i o n u n t i l the charge reached a temperature of about 6 5 O 0 F . a f t e r which the column was cooled, then 10 mm. pressure u n t i l the temperature again reached about 6$0°F. Some comparable TBP s t i l l s f u r t h e r reduce the pressure t o 1 mm. but since t h i s p a r t i c u l a r apparatus was not designed f o r such low pressures, the d i s t i l l a t i o n was terminated at 10 mm. To begin operations at atmospheric pressure, a f t e r the s t i l l - p o t was charggd and attached t o the column, c o o l i n g water was passed through the condensers, powdered d r y - i c e placed i n the c o l d t r a p and the g l a s - c o l heater was turned on. A normal procedure i n the operation of packed columns i s t o p r e f l o o d the column before the a c t u a l d i s t i l l a t i o n begins; the purpose of t h i s i s t o completely wet the packing surface t o ensure maximum column e f f i c i e n c y . For two reasons t h i s procedure was not f o l l o w e d : the l i q u i d - d i v i d i n g s t i l l - h e a d has too small a cap a c i t y t o cause column f l o o d i n g and i s i t s e l f f l o o d e d f i r s t . A l s o , i f f l o o d i n g was even approached 21. during the i n i t i a l r e f l u x i n g of a crude, too l a r g e a f r a c t i o n would be l o s t to the c o l d t r a p . As a r e s u l t , the normal slow r a t e of r e f l u x i n g , 1500 t o 2000 ml. per hour, was permitted throughout the complete d i s t i l l a t i o n ; the p o s s i b l e l o s s i n i n i t i a l column e f f i c i e n c y was considered to be not s i g n i f i c a n t . A p r e l i m i n a r y e q u i l i b r i u m p e r i o d of about h a l f an hour was allowed before any d i s t i l l a t e was drawn i n t o the r e c e i v e r . A f t e r t h i s time at the normal r e f l u x i n g r a t e , the r e f l u x - t i m e r was set to give a r e f l u x - r a t i o of 10:1. The d i s t i l l a t e volume and corresponding vapor temperature were obtained by reading the thermometer, c l o s i n g the i n l e t r e c e i v e r stopcock, and then d r a i n i n g the d i s t i l l a t e i n t o a 250 ml. graduated c y l i n d e r . The s t i l l - p o t temperature was a l s o noted. To o b t a i n the i n i t i a l c o r r e c t volume d i s t i l l e d r e ading, a volume of naphtha corresponding t o t h a t c o l l e c t e d i n the c o l d t r a p , was added t o the graduated c y l i n d e r . The l i g h t f r a c t i o n , as much as 40 ml., was not i t s e l f added t o the d i s t i l l a t e i n the graduate because of i t s h i g h v o l a t i l i t y , but was d iscarded. Subsequent readings, taken at approximate volume i n t e r v a l s of 100 ml. d i d not need f u r t h e r c o r r e c t i o n . A f a l l i n g - o f f of the d i s t i l l a t i o n r a t e due t o i n s u f -f i c i e n t heat input t o the s t i l l - p o t was observed by counting the number of drops f a l l i n g i n t o the d i s t i l l a t e r e c e i v e r during a r e c e i v i n g p e r i o d . The g l a s - c o l heater input was a c c o r d i n g l y adjusted. When the r e f l u x temperature reached o about 250 F., the column and s t i l l - h e a d r i b b o n heaters were 22. turned on. The temperature of the ribbon heater at the s t i l l - h e a d was maintained at about 30°F. below the vapor temperature as i n d i c a t e d by a thermometer placed i n s i d e the heater. An i d e n t i c a l e l e c t r i c a l input was s u p p l i e d to the column ribbon heater; the e x t e r n a l temperature of the column, although undetermined, would be somewhat higher because of the e x t r a i n s u l a t i o n c o v e r i n g the heater. There was l i t t l e danger of d i s r u p t i n g the column operation by sup p l y i n g too much heat by means of the ribbon heaters since both the s t i l l - h e a d and column were vacuum-jacketed; moreover, at high temperature o p e r a t i o n , the heaters and i n s u l a t i o n were e s s e n t i a l i n reducing heat l o s s e s s u f f i c i e n t l y f o r normal d i s t i l l a t i o n . A f t e r the system was evacuated to 10 mm., and the manostat adjusted, d i s t i l l a t i o n at the reduced pressure was performed i n the same way as at atmospheric pressure.. To measure d i s t i l l a t e volumes, however, was a problem. When a conveniehtt volume, again about 100 ml., was c o l l e c t e d i n the r e c e i v e r , the vapor and s t i l l - p o t temperatures were read and the r e c e i v e r i n l e t and evacuating l i n e stopcocks were cl o s e d . The r e c e i v e r was thus i s o l a t e d from the r e s t of the u n i t ; a i r could be vented i n t o i t , the d i s t i l l a t e d rained, and volume measured without d i s r u p t i n g the column o p e r a t i o n . To again evacuate the closed and the r e c e i v e r evacuated, a l s o without d i s r u p t i n g the column o p e r a t i o n . This method r e q u i r e d the readjustment of the manostat each time the d i s t i l l a t e volume was measured. Another method which e l i m i n a t e d the readjustment of the manostat was t o evacuate COX CHART FOR TBP EXTRAPOLATION 24. the r e c e i v e r w i t h an a u x i l i a r y vacuum pump. To o b t a i n the complete TBP curve at atmospheric pressure, the temperatures of the 10 mm. d i s t i l l a t i o n were extra p o l a t e d by means of an enlarged Cox chart (5) as shown i n reduced s i z e i n Figure 4« This chart was constructed i n - the usual way and the f o c a l point determined using vapor pressure values from the l i t e r a t u r e f o r s e v e r a l normal hydrocarbons (18). E x t r a p o l a t i o n gave temperature values c o n s i s t e n t w i t h the atmospheric data when p l o t t e d on a graph of temperature versus volume percent. For example, temperatures of 350oF. and 400°F. at 10 mm. gave c o r r e s -ponding e x t r a p o l a t e d values of 6l5°F. and 670°F. at 760 mm. pressure; (the p r e c i s i o n of the e x t r a p o l a t e d temperatures decreased t o about £5°F. at high temperatures due t o the condensed temperature s c a l e of the Cox chart.) I n t h i s way, data f o r TBP curves, complete t o a temperature of about 300°F., were computed. (b) EFV S t i l l The procedure f o l l o w e d f o r the EFV determinations was e s s e n t i a l l y as p r e s c r i b e d by Othmer e t , a l . ( 1 5 ) • Both atmospheric and reduced pressure d i s t i l l a t i o n s were c a r r i e d out by the same method. P r e l i m i n a r y p r e parations c o n s i s t e d of p l a c i n g d r y - i c e i n t o the c o l d t r a p and s t a r t i n g the cooling-water through the condensers. The s t i l l was charged through the thermometer w e l l , a f t e r which the system was evacuated to the d e s i r e d operating pressure. Heat was 25. s u p p l i e d t o the s t i l l - p o t and vapor-arm, the vapor-arm being kept at a temperature about 30OF. higher than the expected i n i t i a l b o i l i n g p o i n t . The temperature of t h e i n i t i a l b o i l i n g p o i n t corresponded t o the f i f t h drop of d i s t i l l a t e f a l l i n g i n t o the d i s t i l l a t e (as suggested by Othmer e t , a l . ) ; the corresponding volume measurement wan not taken as zero, but as the volume of the l i g h t f r a c t i o n s c o l l e c t e d i n the c o l d t r a p . To help i n making the r e c y c l e c o n t r o l e f f e c t i v e a p o i n t e r was attached t o the end of the stopcock so t h a t the proper p o s i t i o n could be r e a d i l y a t t a i n e d as shown by a c i r c u l a r s c a l e . Furthermore, the r e c y c l e stream was p a r t i a l l y v aporized by means of the r e c y c l e heater so t h a t i n t e r m i t t e n t bubble's passed through the stopcock. The bubbles aided i n es t i m a t i n g the r a t e of r e c y c l e as w e l l as prevented super-h e a t i n g of the charge i n the s t i l l - p o t . The volume i n the r e s e r v o i r was increased by i n c r e a s i n g the s t i l l - p o t heater. E q u i l i b r i u m was e s t a b l i s h e d when the d i s t i l l a t e was of the same composition as the vapor i n e q u i l i b r i u m w i t h the l i q u i d charge. To accomplish t h i s the l i q u i d temperature was kept constant r a t h e r than the d i s t i l l a t e volume as suggested by Othmer et a l . I n t h i s way small temperature changes could be n o t i c e d and heat s u p p l i e d a c c o r d i n g l y , whereas small volume changes could not be n o t i c e d soon enough to permit easy c o r r e c t i v e adjustment. A f t e r normal d i s t i l l a t i o n and r e c y c l e r a t e s of about 120 drops 26. per hour were e s t a b l i s h e d , the only c o n t r o l necessary was the heat input t o the s t i l l ; the r e c y c l e stopcock was kept i n the same p o s i t i o n throughout the d i s t i l l a t i o n . For ob t a i n i n g increased volumes of d i s t i l l a t e , the s t i l l temperature was slow l y increased i n increments of about 50°F., w i t h a corresponding increase i n vapor-arm temperature. As the temperature increased the d i s t i l l a t i o n r a t e would i n c r e a s e w i t h r e s u l t i n g higher volumes of d i s t i l l a t e . E q u i l i b r i u m was assumed when no volume change was observed over a pe r i o d of about i hour at a constant s t i l l temperature, the complete time f o r a s i n g l e measurement t a k i n g up to 4 hours. Since the whole determination could not be made i n one eight hour day, the d i s t i l l a t i o n had t o be d i s c o n t i n u e d before i t was completed. To permit easy s t a r t - u p next day, the r e c y c l e stopcock was closed t r a p p i n g the d i s t i l l a t e i n the r e s e r v o i r . The vacuum l i n e a l s o was cl o s e d w i t h a p i n c h -cock (during reduced pressure d i s t i l l a t i o n ) . The f o l l o w i n g day the d i s t i l l a t i o n c o uld be conveniently continued a t a temperature another increment above the one used p r e v i o u s l y . The volume i n the c o l d t r a p was checked f o r l o s s due t o evaporation. The f l a s h curves at e i t h e r atmospheric o r 10 mm. pressure could be drawn d i r e c t l y from the data f o r the l i q u i d temperature and the c o r r e c t e d volume o f d i s t i l l a t e . 27. ( c ) C a l i b r a t i o n of Column The t h e o r e t i c a l p l a t e e f f i c i e n c y of the TBP column was checked by r e f l u x i n g at t o t a l r e f l u x a mixture of the p u r i f i e d benzene and carbon t e t r a c h l o r i d e . A charge of about 2 1. of 20 mole percent carbon t e t r a c h l o r i d e was r e f l u x e d f o r two hours, then s m a l l samples of the overhead and s t i l l -pot mixturds were taken. These were analyzed by r e f r a c t i v e index a f t e r which r e f l u x i n g was continued f o r another three hours to ensure that e q u i l i b r i u m had been a t t a i n e d . Second samples drawn gave the same r e f r a c t i v e index values as the f i r s t . The r e f r a c t i v e index values at 2 5 ° C f o r the s t i l l -pot composition and overhead were 1.4916 and 1.4783, r e s -p e c t i v e l y . The r e f r a c t i v e index-composition r e l a t i o n s h i p was t h a t recommended by the U.S. Bureau of Mines (20) and the benzene-carbon t e t r a c h l o r i d e v a p o r - l i q u i d e q u i l i b r i u m data were obtained from the I n t e r n a t i o n a l C r i t i c a l Tables ( 7 ) . The p l a t e e f f i c i e n c y of the column was determined by the usual McCabe and T h i e l e method (10) u s i n g an enlarged vapor-l i q u i d e q u i l i b r i u m diagram. The value obtained by t h i s method was 11.4 e q u i v a l e n t t h e o r e t i c a l p l a t e s f o r a column of 22 inches of packing i n c l u d i n g the s t i l l i - p o t * and s t i l l -head as i l l u s t r a t e d i n F i g u r e $. 29. VI. RESULTS For each of the crude o i l s t e s t e d , three charac-t e r i s t i c curves were determined: the atmospheric TBP, ^.atmospheric EFV, and the 10 mm. EFV curves. The curves are a l l p l o t t e d w i t h the volume percent as a b s c i s s a and temperature as o r d i n a t e . F i g u r e s 8a - 8h show the atmospheric TBP and EFV curves; the numerical data appear i n l i a b l e I . The EFV curves at 10 mm. and atmospheric pressure appear i n F i g u r e s lOa-lOh. The r e l a t i o n s h i p between the atmospheric TBP and EFV 50 percent b o i l i n g p o i n t s can be approximated by a straight l i n e . The data p o i n t s are given i n SEable I I and shown g r a p h i c a l l y i n F i g u r e 6 w i t h the best s t r a i g h t l i n e f i t t e d by the method of l e a s t squares. The dotted l i n e corresponds t o the c a l c u l a t e d r e s u l t s of Okamoto and Van Winkle (14) f o r mixtures of pure hydrocarbons assuming i d e a l behaviour. I f the EFV curve i s assumed t o be n e a r l y a s t r a i g h t l i n e , then a slope and the 50 percent p o i n t would c h a r a c t e r -i z e i t . An i n s p e c t i o n of the TBP and EFV slopes i n d i c a t e s that an approximately constant slope d i f f e r e n c e between the two curves e x i s t s . The average slope d i f f e r e n c e i s c a l c u l a t e d t o be 3.511 -0.271 degrees per volume percent where 0.271 i s the p r e c i s i o n . The value 3.511 i s subtracted from the TBP slope g i v i n g the slope of the p r e d i c t e d EFV curve. The constant slope d i f f e r e n c e i s represented by a 30. CORRELATION OF TBP a EFV 5 0 % BOILING POINTS 450 500 550 600 650 X =. EFV 50 PERCENT BOILING POINT ° F. FIG. 6 COMPARISON OF SLOPE CORRELATIONS FIG. 7 L E D U C - W O O D B ' E N D C R U D E 32. J O S E P H L A K E C R U D E 0 I 1 1 1 1 1 1 1 1 J 0 20 40 6 0 80 100 VOLUME PERCENT FIG. 8 b 34. TEXAS PIPELINE CRUDE 0 20 40 60 80 100 V O L U M E P E R C E N T FIG.8C 35 PEMBINA CRUDE o» i 1 1 1 1 1 1 1— J 1 0 2 0 4 0 6 0 8 0 100 V O L U M E P E R C E N T FIG.8d W I Z A R D L A K E C R U D E 37. R E D W A T E R CRUDE For atmosj >heric pressu re A. f 1 j 1 \ / / i 1 1 r ^ ^ ^ ^ i 1 1 O 1 1 1 // / / • 1 i 1 • — — • . 1 i 800 600 • 400 ut or < CC U l Q. U J 200 20 40 VOLUME PERCENT FIG. 8f 60 80 100 S T E T T L E R C R U D E GOLDEN SPIKE CRUDE 40. 45 degree l i n e on a p l o t of EFV slope as ordinate and TBP slope as a b s c i s s a . This p l o t i s given by Okamoto and Van Winkle as c a l c u l a t e d f o r the hydrocarbon mixtures. I t i s reproduced i n F i g u r e 7 showing the data p o i n t s , a l s o l i s t e d i n Table I I , f o r the crudes. Included on t h i s p l o t i s a c o r r e l a t i o n of the TBP and EFV slopes proposed by Nelson and Harvey determined from data on petroleum f r a c t i o n s (12). The a p p l i c a t i o n of the proposed c o r r e l a t i o n s i s i n d i c a t e d i n F i g u r e s 8a - 8h. The atmospheric TBP and EFV experimental curves as w e l l as the p r e d i c t e d curves, the dotted l i n e s , are shown f o r each crude. The p r e d i c t e d curves show the best accuracy i n the r e g i o n 10-60 volume percent. Phase diagrams, constructed from the EFV data at atmospheric and 10 mm. pressures, are shown i n Figu r e 9. The 20 and 60 percent vaporized values were chosen as being most accurate and convenient f o r determining the f o c a l p o i n t s of the v a r i o u s crudes. No f u n c t i o n of e i t h e r the TBP or EFV curves was found to correspond t o the r e l a t i o n between the f o c a l p o i n t s and, as a r e s u l t , no c o r r e l a t i o n i s g i ven f o r l o c a t i n g them. I t i s evident t h a t i f some means were a v a i l a b l e f o r l o c a t i n g the f o c a l p o i n t s then an EFV curve at one pressure would determine i t f o r any other pressure. For comparison, the f o c a l point f o r a petroleum stock, stock I , i s given as determined by Okamoto and Van PHASE DIAGRAM FIG. 9 10 1 0 ' io UJ _ J < o CO CD O - 5 >-IO or O cr UJ U J CO UJ or A GOLDEN SPIKE 0 TEXACO PIPELINE V J O S E P H L A K E <D S T E T T L E R • WIZARD L A K E " f P E M B I N A E D REDWATER O W 0 0 D B E N D - L E D U C ® STOCK I - m m - ® 10 • i r i—|—i I I i j i i i i j I i i i | i 111 j 1 ]—p 2 0 0 0 4 0 0 600 1000 TEMPERATURE F , R E C I P R O C A L S C A L E 1500 42 Winkle (13). This f o c a l p o i n t i s only s l i g h t l y s h i f t e d f o r a s e r i e s of stocks of d i f f e r e n t weights. An attempt was made to u t i l i z e the U.O.P. charac-t e r i z a t i o n f a c t o r , K, fbr c o r r e l a t i n g purposes. Maxwell's method (22) was used i n determining K from the 2 0 , 5 0 , and 80 percent TBP temperatures, the TBP slope, and the API g r a v i t y f o r each crude. The K values determined'ranged from 11 . 6 0 t o 31 .90 w i t h no apparent r e l a t i o n t o the other v a r i a b l e s c o r r e l a t e d . JOSEPH LAKE EFV PEMB INA EFV WIZARD LAKE EFV 47. REDWATER EFV 48. r 8 0 0 20 40 6 0 80 100 PERCENT VAPORIZED FIG. lOf STETTLER EFV WOODBEND-LEDKC E F V 50. 8 0 0 0 20' 40 60 80 100 PERCENT VAPORIZED FIG. lOh 51. TABLE i : WIZARD LAKE TBP Temp. OF V o l . % EFV (ATM) Temp. °F V o l . 93 1.7 152 1.0 124 3.8 248 6.0 165 6.1 288 12.0 190 9.6 325 17.0 203 11.3 363 24.0 237 15.1 392 28.0 279 20.1 457 39.0 336 . 26.0 522 49.0 397 32.2 583 58.0 457 38.6 653 67.0 487 £ 41.7 680 70.0 586 51.7 650 28.2 719 65.2 760 68.3 EFV 10 (MM) Temp. OF V o l . % 179 203 280 343 405 457 588 16.2 20.2 33.2 45.2 53.2 62.2 76.2 ± e x t r a p o l a t e d TBP Temp. °F V o l . % 104 122 157 187 213 257 295 338 372 A 427 472 544 601 670 726 760 4.5 6.0 8 .4 12.0 17.5 21.9 26.1 32.1 33.5 41.6 48.1 54.6 61.1 68.5 73.4 77.0 TEXAS PIPELINE EFV (ATM) Temp. °F V o l . f EFH 10 (MM) Temp. °F V o l . % 133 1.0 172 15.0 -216 6.0 183 18.0 244 7.0 . 205 22.0 261 11.0 215 24.0 279 15.0 270 34.0 313 21.0 327 45.0 .372 32.0 387 55.0 426 41.0 442 63.0 442 44.0 447 67.0 491 < '53.0 531 59.0 563 64.O 615 72.0 ft e x t r a p o l a t e d 52. JOSEPH LAKE TBP EFV (ATM) EFV 10 (MM) Temp. °F V o l . % •femp.oF' V o l . $ Temp. OF V o l . % 108 1.2 208 0.2 158 10.8 124 1.9 286 4.0 226 24.8 183 4.7 293 5.6 306 38.8 200 6.7 302 6.6 345 45.8 225 9.6 322 10.6 394 55.8 261 14.6 340 14.6 417 59.8 318 20.9 385 22.6 484 70.8 358 26.6 437 31.6 ft 498 42.6 429 32.7 558 53.6 471 37.7 615 63.6 544 44.5 673 72.6 587 50.6 644 57.0 704 6 4.I 778 70.8 4 e x t r a p o l a t e d PEMBINA TBP EFV (ATM) EFV (10 MM) Temp. °F V o l . % Temp. °F V o l . $>. Temp. °F V o l . % 93 1.6 158 0.6 189 15.4 122 2.8 262 6.0 214 18.4 .145 4.0 270 8.0 286 30.4 196 8.4 284 1 0 . 0 349 40.4 252 14.8 290 12.0 405 48.4 297 20.0 333 18.0 484 60.4 354 25.7 379 25.0. 540 67.0 414 30.6 455 36.0 591 73.0 468 36.0 520 46.O 507 40.9 581 56.0 ft 646 64.O 566 45.4 682 69.0 628 51.9 691 58.3 772 66.0 ft ex t r a p o l a t e d 53. REDWATER TBP EFV (ATM)- EFV (10 MM) Temp, °F V o l . $ Temp. °F V o l . $ Temp. °F V o l . % 81 2.3 151 0.6 215 22.0 133 4.7 261 7.0 243 27.0 160 6.1 273 8.0 293 36.0 189 8.2 298 12.0 334 43.0 214 11.5 343 19.0 359 47.0 280 19.8 388 26.0 381 52.0 338 25.0 457 37.0 429 60.0 385 29.5 529 48.0 477 65.0 424 32.8 579 56.0 489 66.0 ft • r' 631 63.0 554 72.0 466 35.3 669 69.0 523 42.3 618 50.6 662 55.4 714 60.3 752 66.0 o ft ext r a p o l a t e d LEDUC-WOODBEND TBP Temp. °F V o l . $ 97 ^ H I 2.3 142 3.9 \l\ & 198 io.O 263 2011 307 24.8 401 35.g 484 45.0 Ilk 51.0 5?6 56.5 711 6 4 ' 5 711 70.1 EFV (ATM) EFV (10 MM) Temp. °F V o l . % Temp. °F V o l . % 153 0.6 185 11.6 230 4.0 216 19.6 246 6.2 250 26.6 279 12.2 325 42.6 300 17.2 392 53.6 ... 3 2 ? 23.2 482 66.0 370 31.2 572 77.0 423 40.2 487 52.4 554 61.6 603 68.6 669 77.6 ft ex t r a p o l a t e d 54. TBP Temp. °F V o l . % 102 2.2 111 3.3 138 4.7 174 8.1 226 13.8 255 19.1 298 24.0 322 26.8 365 31.6 ft 441 39.9 492 44.9 520 48.3 576 54.6 651 63.1 696 68.3 744 73.3 ft extrapolated TBP Temp. ° F V o l . % 127 3.3 162 , 6.2 225 10.4 252 13.7 332 19.5 392 24.6 ft 487 31.7 538 36.1 570 39.5 598 43.2 658 48.1 712 53.5 752 58.6 800 62.7 ft extrapolated SOLDEN SPIKE EFV (ATM) EFV (10 MM) Temp. ° F V o l . $ Temp. ° F V o l . % 153 2.0 172 ° 11.0 235 6.0 190 14.0 264 10.0 223 30.0 290 , 15.0 273 30.0 329 22.0 336 41.0 378 31.0 392 50.0 414 37.0 442 57.0 459 46.0 487 63.0 502 52.0 541 58.0 574 64.O 617 70.0 646 . 73.0 680 76.0 STETTLER EFV (ATM! EFV (10 MM) 192 III 351 425 498 563 629 680 V o l . % Temp. ° F V o l . % 1.0 255 19.4 5.0 343 32.4 7.0 399 39.4 12.0 471 49.4 22.0 525 57.0 33.0 586 64.O 42.0 649 70.0 51.0 57.0 TABLE I I SAMPLE TBP EFV P r e d i c t e d EFV 50% p o i n t ° F slopeT / V o l $ 50% point°F slope'F/vol.^ 5<$ point °F slope °F/Vol. % - f t ft Texas P i p e l i n e 503 8.93 477 5.70 464 5.42 Golden Spike 534 9.10 490 5.83 491 5.59 Woodbend-Leduc 527 8.83 475 5.63 485 5.32 Joseph Lake 584 9.10 540 5.63 535 5.59 Pembina 610 .10.33 546 6.67 557 6.82 Wizard Lake 571 9.77 531 6.47 523 6.26 Redwater 604 10.80 541 6.47 552 7.29 S t e t t l e r 678 10.80 621 7.17 616 7.29 ft average d e v i a t i o n of 50 percent p o i n t = 8.1°F 56. VII.DISCUSSION OF RESULTS E m p i r i c a l c o r r e l a t i o n s r e q u i r e a s u f f i c i e n t amount of data t o adequately represent the complete range of v a r i a b l e s . This i s d e f i n i t e l y a l i m i t a t i o n w i t h c o r r e l a t i o n s f o r A l b e r t a crude o i l s ; although TBP data are more e a s i l y a v a i l a b l e , both TBP and the corresponding EFV data i n a d d i t i o n t o those given here are almost n o n - e x i s t e n t . The charts r e s u l t i n g from the t e s t s on the e i g h t A l b e r t a crudes a r e , t h e r e f o r e , somewhat l i m i t e d i n t h e i r value as c o r r e l a t i o n s . The curves obtained f o r the i n d i v i d u a l samples, however, could be u s e f u l i n design c a l c u l a t i o n s . The c o r r e l a t i o n of the TBP and EFV 50 percent b o i l i n g p o i n t s given here adds weight t o t h a t of Okamoto and Van Winkle. I t should be noted that t h e i r 50 percent p o i n t s are not experimentally determined but are c a l c u l a t e d f o r mixtures of pure hydrocarbons s i m u l a t i n g petroleum f r a c t i o n s . P r o p e r t i e s of the components are a v a i l a b l e f o r these c a l c u l a t i o n s , e s p e c i a l l y f o r the common hydrocarbons i n the b o i l i n g range used by Okamoto and Van Winkle (150 t o 350°F). When i t becomes evident t h a t the TBP and EFV slope p l o t i s a l s o corroborated by a s i m i l a r p l o t f o r the crudes, the s i m i l a r i t y i s even more s i g n i f i c a n t . This approach t o the c h a r a c t e r i z a t i o n curves of crude o i l s may prove t o be more u s e f u l t h a n i the reference t o petroleum f r a c t i o n s , the usual method adopted. The accuracy of the EFV 50 percent p o i n t determined 57. by the Okamoto and Van Winkle method i s good when compared w i t h that obtained f o r the best A.S.T.M. - EFV c o r r e l a t i o n . The c o r r e l a t i o n of Edraister and P o l l o c k (4) gives the smallest mean d e v i a t i o n of ±12.5°F. i n the p r e d i c t e d f l a s h 50 percent p o i n t f o r petroleum f r a c t i o n s of a l l the current a v a i l a b l e c o r r e l a t i o n s , as shown by Ghu and S t a f f e l ( 2 ) . The lower value of - 8.1°F. was obtained f o r the crudes. Although t h e A.S.T.M. d i s t i l l a t i o n s are somewhat l e s s r e p r o d u c i b l e than the TBP d i s t i l l a t i o n s , the r e l a t i v e l y s m a ll mean d e v i a t i o n i s very f a v o u r a b l e . In t h e i r slope c o r r e l a t i o n Okamoto and Van Winkle c a l c u l a t e d the 10-70 percent slopes f o r the hydrocarbon mixtures. This i s a slope commonly used i n slope c o r r e l a t i o n s ; however, s i n c e both the TBP and EFV curves f o r crudes are s t r a i g h t only f o r the 25-55 percent range, these slopes were used i n preference. Very l i t t l e change i n slope would be observed i f the 10-30 percent slope was used as suggested by Edmister and P o l l o c k (4). si n c e the v a r i a t i o n i n t h i s r egion was only s l i g h t . Although the TBP slopes are approximately constant over the complete range of 10-70 percent, the EFV slopes have a pronounced curve upward i n the 55-70 percent range. The 25-55 percent slopes, t h e r e f o r e , are most c h a r a c t e r i s t i c . The use of atmospheric TBP and EFV d i s t i l l a t i o n s i n s t e a d of at p r e c i s e l y 760 mm. pressure may be questioned. V a r i a t i o n s i n atmospheric pressure have been noted from 5 8 . 757 "to 760 mm. f o r the i n d i v i d u a l determinations. The temperature adjustment corresponding t o t h i s pressure v a r i a t i o n i s no more than 2°F. as estimated from the Cox chart and i s of the order of accuracy that the Cox chart can be read. The us u a l method i s t o neglect t h i s small temperature discrepancy. The C a l i f o r n i a Research Corporation p u b l i c a t i o n (1) on the comprehensive a n a l y s i s of Redwater urude showed the TBP curve as obtained at atmospheric pressure (358 mm.) without c o r r e c t i o n . S i m i l a r adjustment of the EFV data was'neglected f o r the same reason. Chu and S t a f f e l ( 2 ) , i n t h e i r recent survey of the c o r r e l a t i o n s of A.S.T.M. and EFV curves gave an i n t e r e s t i n g d i s c u s s i o n on the use of the'U.O.P. c h a r a c t e r i z a t i o n f a c t o r , K, as a c o r r e l a t i n g v a r i a b l e . The w r i t e r s agree t h a t the K f a c t o r c o r r e c t i o n i s a p p l i e d to the 50 percent p o i n t of the p r e d i c t e d f l a s h curve w i t h some advantage i n such c o r r e l a t i o n s as that by Edmister and P o l l o c k ( 4 ) ; however, they doubt th a t i t s use a c t u a l l y accounts f o r the d i f f e r e n c e i n a r o m a t i c i t y of the f r a c t i o n s : " I t i s assumed that the c h a r a c t e r i z a t i o n f a c t o r would have as much e f f e c t on any point on the f l a s h curve as i t does on the 50 percent p o i n t . As i t does not appear t o b e n e f i t the 10 and 70 percent p o i n t s some doubt i s cast on the v a l i d i t y of the c o r r e c t i o n by the c h a r a c t e r i z a t i o n f a c t o r at the 50 percent p o i n t " (2) The a p p l i c a t i o n o f a K f a c t o r c o r r e c t i o n t o the TBP-EFV c o r r e l a t i o n s would be l i k e w i s e c r i t i e i z e d . 59. Some aspects of the i n i t i a l determinations of the TBP and EFV curves should be f u r t h e r considered. One of the problems concerning the TBP d i s t i l l a t i o n was the method of extending the. second p o r t i o n o f the curve obtained at 10 mm. to atmospheric pressure. The standard method has heen to f o l l o w the l i n e f o r the n - p a r a f f i n of equal b o i l i n g p o i n t on a Cox chart to determine the corresponding atmospheric temperature. A p o s s i b i l i t y f o r t e s t i n g the v a l i d i t y of t h i s method of e x t r a p o l a t i o n appeared t o be a complete TBP d i s t i l l a t i o n at 10 mm. pressure and the compar-i s o n with one p a r t i a l l y completed at atmospheric pressure. When.: t h i s was attempted the qu a n t i t y of condensate removed by the dryQice t r a p was excessive making evacuation to 10 mm. im p o s s i b l e . Careful!,, reference t o the Cox chart i n d i c a t e d t h a t a l l the l i g h t e s t f r a c t i o n s , up to about 20 percent would be vaporized at 10 mm. and at room temperature. The reduced pressure d i s t i l l a t i o n was u s u a l l y begun at about 35 volume percent. The overlap of the two d i s t i l l a t i o n s was considered too s m a l l to be s i g n i f i c a n t ; as a r e s u l t , the complete 10 mm. d i s t i l l a t i o n was abandoned. No gross e r r o r i n the TBP curve i s p o s s i b l e , however, si n c e the ext r a p o l a t e d p o r t i o n of the curve f o l l o w s c o n s i s t e n t l y from the i n i t i a l p a r t of the curve. The a p p l i c a t i o n of the Cox chart f o r the e x t r a -p o l a t i o n of EFV curves has, quite j u s t l y , r e c e i v e d more c r i t i c i s m . Since the o i l f r a c t i o n s i n a TBP d i s t i l l a t i o n 60. are r e l a t i v e l y narrow - f r a c t i o n s , i t i s l i k e l y t h a t the assumption t h a t they can be c h a r a c t e r i z e d by n - p a r a f f i n hydrocarbons i s v a l i d . I n the EFV determinations the con-densate volume i n c l u d e s components of a wide b o i l i n g range; the obvious p o s s i b l e e r r o r i s that t h i s o i l f r a c t i o n does not have the same chemical c h a r a c t e r i s t i c s as the n - p a r a f f i n of the same b o i l i n g p o i n t . The Cox chart method f o r extending EFV data t o high pressures has been sh^mm to be i n e r r o r by Edmister and P o l l o c k (4) who a l s o present a c o r r e l a t i o n s u i t a b l e f o r t h i s purpose. For subatmospheric pressures, however, the Cox chart i s g e n e r a l l y accepted as a convenient and dependable means f o r e x t r a p o l a t i n g EFV data a v a i l a b l e at two pressures. S l i g h t l y l e s s dependable i s the p l o t of the l o g a r i t h m of the pressure versus the r e c i p r o c a l temperature (Figure 9)5 however, i t a l s o i s q u i t e adequate i n the low pressure r e g i o n . The f o c a l p o i n t s f o r the crudes, as shown on the l a t t e r p l o t , are l o c a t e d at pressures so f a r beyond the c r i t i c a l pressures of petroleum f r a c t i o n s that the question a r i s e s as t o t h e i r s i g n i f i c a n c e . The l o c a t i o n of a f o c a l p o i n t i s a f u n c t i o n of the absolute value of the 50 percent p o i n t at atmospheric pressure and the temperature d i f f e r e n c e of the two 50 percent p o i n t s . F o c a l p o i n t s o f other crudes would have to be com-pared i n the l i g h t of these two v a r i a b l e s before any conclusions could be drawn. \ 61. V I I I . BIBLIOGRAPHY 1. C a l i f o r n i a Research C o r p o r a t i o , Richmond, C a l i f . , Report on Redwater Crude a n a l y s i s , Feb. 9 (1953)• 2. Chu, J . C , and S t a f f e l , E . J ., J , I n s t , of Pet., Ult 3 7 5 , 9,2 ( 1 9 5 5 ) . 3 . C o l l i n s , F.C., and Vernon, L., ' ' Ind. Eng. Chem., 1 8 , 673 ( 1 9 4 6 ) . 4 . Edmister, W. C , and P o l l o c k , D.H.. Chem. fing. prog., ^ 905 (1948). 5 . Cox, E.R., Ind Eng. Chem., 1£, 592 ( 1 9 2 3 ) . 6 . Gilmont, R., Anal. Chem., 22, 157 (1951) .^ 7 . I n t e r n a t i o n a l C r i t i c a l Tables, McGraw-Hill Book Co., N.Y., 2> 309 ( 1 9 2 8 ) . 8 . I b i d . , 2, 2 8 7 , ( 1 9 2 8 ) . 9 . Katz, O.L., and Brown, G.G., Ind. Eng. Chem., 2 £ , 1278 ( 1 9 3 3 ) . 1 0 . McCabe, W.L., and T h i e l e , E.W., Ind. Eng. Chem., 12, 605 ( 1 9 2 5 ) . 1 1 . Nelson, W.L., and Sonders, M., J . P et. Engr., 2> 1 . 131 ( 1 9 3 1 ) . 1 2 . Nelson, W.L., and Harvey, R.J., O i l Gas J o u r n a l , 22, June 1 7 , ( 1 9 4 8 ) . 1 3 . Okamoto, K.K., and Van Winkle, M., P e t . R e f i n e r , 8, 113 (1949). 1 4 . I b i d . , 1, 729 ( 1 9 5 0 ) . 15. Othmer, D.F., Ten Eyck, E.H., and T o l i n , S., Ind. Eng. Chem., £2, 1607 ( 1 9 5 1 ) . 1 6 . P a c k i e , J.W., Trans. Am. I n s t . Chem. Engrs., 2Z>-51 ( 1 9 4 9 ) . 1 7 . PiroomoV, R.S., and Beiswenger, G.A., Proc. Am. P e t . I n s t . , 1 0 , 2 , Sec. I I , 52 ( 1 9 2 9 ) . 62. 18. Rubber Chemical Company, Handbook of Physicaland Chemistry, 2016; (1953). 19. Waldichuk, M., M.A.Sc. Thesis, U.B.C., (1950). 20. Ward, A.L., U.S. Bur. Mines Tech. Papers, 600 (1939). 21. Watson, K.M., and Nelson, W.L., Ind. Eng. Chem., 2£, 880 (1933). 22. Maxwell, J.B., Data Book on Hydrocarbons, van Nostrand Co., N.Y.,(]9 50). 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0059288/manifest

Comment

Related Items