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A mathematical model for cement kilns Darabi, Pirooz
Abstract
Rotary kilns have numerous industrial applications including cement production. Frequent operational problems such as low thermal efficiency, refractory failure, and poor product quality have prompted extensive efforts to improve and optimize their design. Mathematical modeling and Computational Fluid Dynamics constitute effective tools recently used for these purposes. A cement kiln consists of three major parts: the hot flow, the bed, and the wall. A CFD code which had the capability of simulating the hot gas was developed further to simulate the kiln. In the present work, two 1-D mathematical models are proposed and implemented in the existing CFD code. The first model consists of the steady-state solution for the material and temperature evolution within the bed. The second one simulates tire combustion in the kiln. The tire burning model assumes that tire combustion occurs in two major successive steps, devolatization and char combustion. For the devolatization model, external heat and mass transfer, three parallel reactions, and enthalpy effects are considered the dominant phenomena. The char combustion model considers the enthalpy effect and the external mass transfer. With the aid of the developed model, full-scale industrial cement kilns under steady-state and realistic operational conditions are simulated. In addition, cement kilns with combustion of full scrap tires in the middle of them are mathematically modeled. The limits and feasibility of tire combustion are further explored by running numerical simulations with different tire flow rates and different injector locations. The flow field, temperature distribution and species distribution are presented. Analysis of the results indicates that, with the help of the proposed model, a better understanding of the important processes within cement kilns can be obtained. The model can be used for addressing operational problems and optimizing designs. It is also concluded that successful firing of tires can lead to a cheaper, longer lasting, and less polluting kiln.
Item Metadata
Title |
A mathematical model for cement kilns
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2007
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Description |
Rotary kilns have numerous industrial applications including cement production. Frequent operational
problems such as low thermal efficiency, refractory failure, and poor product quality have prompted
extensive efforts to improve and optimize their design. Mathematical modeling and Computational Fluid
Dynamics constitute effective tools recently used for these purposes.
A cement kiln consists of three major parts: the hot flow, the bed, and the wall. A CFD code which had
the capability of simulating the hot gas was developed further to simulate the kiln. In the present work,
two 1-D mathematical models are proposed and implemented in the existing CFD code. The first model
consists of the steady-state solution for the material and temperature evolution within the bed. The second
one simulates tire combustion in the kiln. The tire burning model assumes that tire combustion occurs in
two major successive steps, devolatization and char combustion. For the devolatization model, external
heat and mass transfer, three parallel reactions, and enthalpy effects are considered the dominant
phenomena. The char combustion model considers the enthalpy effect and the external mass transfer.
With the aid of the developed model, full-scale industrial cement kilns under steady-state and realistic
operational conditions are simulated. In addition, cement kilns with combustion of full scrap tires in the
middle of them are mathematically modeled. The limits and feasibility of tire combustion are further
explored by running numerical simulations with different tire flow rates and different injector locations.
The flow field, temperature distribution and species distribution are presented. Analysis of the results
indicates that, with the help of the proposed model, a better understanding of the important processes
within cement kilns can be obtained. The model can be used for addressing operational problems and
optimizing designs. It is also concluded that successful firing of tires can lead to a cheaper, longer lasting,
and less polluting kiln.
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Genre | |
Type | |
Language |
eng
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Date Available |
2011-03-11
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0080783
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.