Introduction to Computational Mass Transfer: With Applications to Chemical Engineering

425 Pages·2017·15.648 MB·English

by  Kuo-Tsung Yu, Xigang Yuan (auth.)

Heat and Mass Transfer
Kuo-Tsung Yu
Xigang Yuan
Introduction to
Computational
Mass Transfer
With Applications to Chemical
Engineering
Second Edition
Heat and Mass Transfer
Series editors
D. Mewes, Hannover, Germany
F. Mayinger, München, Germany
More information about this series at http://www.springer.com/series/4247
Kuo-Tsung Yu Xigang Yuan
(cid:129)
Introduction
to Computational
Mass Transfer
With Applications to Chemical Engineering
Second Edition
123
Kuo-TsungYu Xigang Yuan
Schoolof Chemical Engineering Schoolof Chemical Engineering
andTechnology andTechnology
Tianjin University Tianjin University
Tianjin Tianjin
People’sRepublic ofChina People’sRepublic ofChina
Additional material tothis bookcanbedownloaded from http://extras.springer.com.
ISSN 1860-4846 ISSN 1860-4854 (electronic)
Heat andMassTransfer
ISBN978-981-10-2497-9 ISBN978-981-10-2498-6 (eBook)
DOI 10.1007/978-981-10-2498-6
LibraryofCongressControlNumber:2013957426
©SpringerNatureSingaporePteLtd.2014,2017
Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart
of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,
recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission
orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar
methodologynowknownorhereafterdeveloped.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this
publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom
therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
The publisher, the authors and the editors are safe to assume that the advice and information in this
book are believed to be true and accurate at the date of publication. Neither the publisher nor the
authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor
foranyerrorsoromissionsthatmayhavebeenmade.
Printedonacid-freepaper
ThisSpringerimprintispublishedbySpringerNature
TheregisteredcompanyisSpringerNatureSingaporePteLtd.
Theregisteredcompanyaddressis:152BeachRoad,#22-06/08GatewayEast,Singapore189721,Singapore
Preface
Withtherapiddevelopmentandcontinuingadvancesofcomputertechnologiesand
numerical computation, many new multidisciplinary research areas have emerged,
includingcomputational chemistry, computational physics, computational biology,
and others. It is recognized that computational methodology has now became one
ofthethreebasicmethodologiesofconductingscientificandengineeringresearch,
along with theoretical investigation and experimental studies.
In the 1970s, the cross-disciplinary studies of fluid dynamics and numerical
computation had led to the new research area of computational fluid dynamics
(CFD). This multidisciplinary development later on extended to heat transfer; and
consequently the field of computational heat transfer (CHT) or numerical heat
transfer (NHT) wasintroduced. Theestablishmentofthese twonewresearchareas
has helped scientists and engineers solve many difficult problems, such as the
prediction of flow and heat transfer behaviors in engineering design and
applications.
Nevertheless, what chemical engineers deal with includes not only fluid flows
and heat transfer but also mass transfer and chemical reactions. The detailed
informationofmasstransfer,especiallytheconcentrationdistribution,isessentialto
the design and the assessment of chemical equipment as it serves as the basis in
evaluating the process effectiveness or efficiency. The conventional approach to
predict the concentration field is by the empirical method which is not only unre-
liable but also lacking of theoretical foundation. Thus a rigorous method for
accurate predictions needs to be investigated.
Mass transfer processes are complicated, usually involving turbulent flow, heat
transfer, multiple phases, chemical reactions, unsteady operation, as well as the
influences from internal construction of the equipment and many other factors. To
study such a complicated system, we propose a novel scientific computing
framework in which all the relevant equations on mass transfer, fluid dynamics,
heat transfer, chemical reactions,andall otherinfluencingfactorsareinvolvedand
solved numerically. This is the main task and research methodology of computa-
tional mass transfer (CMT).
v
vi Preface
Moreover,allmasstransferprocessesinvolvethediffusionthroughtheinterface
between adjacentphases.Interfacialeffects,suchastheMarangoniconvectionand
the Rayleigh convection, cannot be ignored. Therefore, the study of interfacial
effects is another important aspect of CMT.
In recent years, we explored in this new area on the closure of the differential
turbulentmasstransferequationbyproposingthetwo-equationc02(cid:2)ec0 modeland
the Reynold’s mass flux (fluctuating mass flux) u0c model. Our approach has been
successfully applied to various chemical processes and equipments, including
distillation, absorption, adsorption, catalytic reaction, and fluidized chemical
processes. The interfacial behaviors of mass transfer were also studied by both
simulations and experiments.
This book is chiefly based on our published research work and graduate dis-
sertationsintheareaofCMT.Thepurposeofwritingthisbookisfirsttoserveasa
textbook for the graduate course titled “Introduction to the Computational Mass
Transfer”, offered to the graduate students of Chemical Engineering discipline in
Tianjin University; and second as a reference book for those who are interested in
this area.
The contents of this book can be divided into two parts. The first part, Process
Computation, involves the prediction of concentration, velocity, and temperature
distributions in chemical engineering equipment. The second part, Interface
Computation, concerns the prediction of interfacial effect on mass transfer
behaviors.
Chapter 1 of this book covers the basic equation and models of computational
mass transfer. Chapters 2–6 present the application of computational mass transfer
to discuss the process computation of various gas–liquid contacting and catalytic
reaction as well as fluidized processes and equipment in chemical engineering.
Chapters 7 and 8 deal with the multi-component mass transfer and concentration
behaviornearinterface.Chapters9and10introducethecomputationofMarangoni
andRayleighconvectionsandtheirinfluenceonmasstransferbyusingrespectively
differential equations and the lattice Boltzmann method.
The research works presented in this book were performed in the State Key
Laboratory for Chemical Engineering at Tianjin University under the support of
Chinese National Science Foundation (contract number 20136010, 20736005, and
91434204).ThehelpandencouragementfromtheChemicalEngineeringResearch
Center of Tianjin University is acknowledged.
We warmly welcome any suggestions, discussions, and criticism on this book.
Tianjin, China Kuo-Tsung Yu
December 2015 Xigang Yuan
Contents
1 Basic Models of Computational Mass Transfer.... .... ..... .... 1
1.1 Equation of Mass Conservation and Its Closure.... ..... .... 3
1.2 Turbulent Mass Diffusivity Model .. .... .... .... ..... .... 6
1.3 Conventional Turbulent Mass Diffusivity Model ... ..... .... 6
1.3.1 Turbulent Schmidt Number Model ... .... ..... .... 6
1.3.2 Inert Tracer Model ... .... .... .... .... ..... .... 7
1.4 c02(cid:2)ec Model (Two-Equation Model) ... .... .... ..... .... 7
1.4.1 The c02 and ec0 Equations... .... .... .... ..... .... 8
1.4.2 The c02(cid:2)ec0 Model Equation Sets.... .... ..... .... 17
1.4.3 Determination of Boundary Conditions.... ..... .... 21
1.4.4 Experimental Verification of Model Prediction ... .... 24
1.4.5 Analogy Between Transport Diffusivities .. ..... .... 26
1.4.6 Generalized Equations of Two-Equation Model .. .... 28
1.5 Reynolds Mass Flux Model ... .... .... .... .... ..... .... 29
1.5.1 Standard Reynolds Mass Flux Model . .... ..... .... 29
1.5.2 Hybrid Reynolds Mass Flux Model... .... ..... .... 37
1.5.3 Algebraic Reynolds Mass Flux Model. .... ..... .... 38
1.6 Simulation of Gas (Vapor)–Liquid Two-Phase Flow ..... .... 39
1.7 Model System of CMT Process Computation.. .... ..... .... 45
1.8 Summary .... .... ..... .... .... .... .... .... ..... .... 46
References. .... .... .... ..... .... .... .... .... .... ..... .... 47
2 Application of Computational Mass Transfer (I) Distillation
Process... .... .... .... ..... .... .... .... .... .... ..... .... 51
2.1 Tray Column . .... ..... .... .... .... .... .... ..... .... 54
2.1.1 c02(cid:2)ec0 Two-Equation Model... .... .... ..... .... 54
2.1.2 Reynolds Mass Flux Model. .... .... .... ..... .... 69
2.1.3 Prediction of Multicomponent Point Efficiency... .... 78
vii
viii Contents
2.2 Packed Column.... ..... .... .... .... .... .... ..... .... 90
2.2.1 c02(cid:2)ec Two-Equation Model ... .... .... ..... .... 90
2.2.2 Reynolds Mass Flux Model. .... .... .... ..... .... 95
2.3 Separation of Benzene and Thiophene by Extractive
Distillation ... .... ..... .... .... .... .... .... ..... .... 103
2.4 Summary .... .... ..... .... .... .... .... .... ..... .... 108
References. .... .... .... ..... .... .... .... .... .... ..... .... 109
3 Application of Computational Mass Transfer (II) Chemical
Absorption Process . .... ..... .... .... .... .... .... ..... .... 111
3.1 c02(cid:2)ec Two-Equation Model.. .... .... .... .... ..... .... 113
3.1.1 Absorption of CO by Aqueous MEA in Packed
2
Column... ..... .... .... .... .... .... ..... .... 118
3.1.2 Absorption of CO by Aqueous AMP in Packed
2
Column... ..... .... .... .... .... .... ..... .... 125
3.1.3 Absorption of CO by Aqueous NaOH in Packed
2
Column... ..... .... .... .... .... .... ..... .... 128
3.2 Reynolds Mass Flux Model ... .... .... .... .... ..... .... 134
3.2.1 Absorption of CO by Aqueous MEA in Packed
2
Column... ..... .... .... .... .... .... ..... .... 137
3.2.2 The Absorption of CO by Aqueous NaOH
2
in Packed Column.... .... .... .... .... ..... .... 144
3.3 Summary .... .... ..... .... .... .... .... .... ..... .... 148
References. .... .... .... ..... .... .... .... .... .... ..... .... 148
4 Application of Computational Mass Transfer (III)—Adsorption
Process... .... .... .... ..... .... .... .... .... .... ..... .... 151
4.1 c02(cid:2)e Two-Equation Model for Gas Adsorption .. ..... .... 154
c
4.1.1 c02(cid:2)ec0 Model Equations .. .... .... .... ..... .... 154
4.1.2 Boundary Conditions.. .... .... .... .... ..... .... 157
4.1.3 Evaluation of Source Terms .... .... .... ..... .... 158
4.1.4 Simulated Results and Verification ... .... ..... .... 160
4.1.5 Simulation for Desorption (Regeneration)
and Verification.. .... .... .... .... .... ..... .... 165
4.2 Reynolds Mass Flux Model ... .... .... .... .... ..... .... 167
4.2.1 Model Equations. .... .... .... .... .... ..... .... 167
4.2.2 Simulated Results and Verification ... .... ..... .... 169
4.2.3 Simulation for Desorption (Regeneration)
and Verification.. .... .... .... .... .... ..... .... 171
4.3 Summary .... .... ..... .... .... .... .... .... ..... .... 173
References. .... .... .... ..... .... .... .... .... .... ..... .... 173
Contents ix
5 Application of Computational Mass Transfer (IV)
Fixed-Bed Catalytic Reaction.. .... .... .... .... .... ..... .... 175
5.1 c02(cid:2)e Two-Equation Model for Catalytic Reactor . ..... .... 178
c
5.1.1 Model Equation.. .... .... .... .... .... ..... .... 178
5.1.2 Boundary Conditions.. .... .... .... .... ..... .... 182
5.1.3 Determination of the Source Terms... .... ..... .... 182
5.1.4 The Simulated Wall-Cooled Catalytic Reactor.... .... 183
5.1.5 Simulated Result and Verification.... .... ..... .... 185
5.2 Reynolds Mass Flux Model for Catalytic Reactor .. ..... .... 191
5.2.1 Model Equations. .... .... .... .... .... ..... .... 191
5.2.2 Simulated Result and Verification.... .... ..... .... 194
5.2.3 The Anisotropic Mass Diffusivity .... .... ..... .... 197
5.3 Summary .... .... ..... .... .... .... .... .... ..... .... 200
References. .... .... .... ..... .... .... .... .... .... ..... .... 201
6 Application of Computational Mass Transfer (V) Fluidized
Chemical Process... .... ..... .... .... .... .... .... ..... .... 203
6.1 Flow Characteristics of Fluidized Bed ... .... .... ..... .... 205
6.2 c02(cid:2)ec Two-Equation Model for Simulating Fluidized
Process.. .... .... ..... .... .... .... .... .... ..... .... 208
6.2.1 The Removal of CO in Flue Gas in FFB Reactor .... 208
2
6.2.2 Simulation of Ozone Decomposition in the Downer
of CFB Reactor.. .... .... .... .... .... ..... .... 219
6.3 Reynolds Mass Flux Model for Simulating Fluidized
Process.. .... .... ..... .... .... .... .... .... ..... .... 223
6.3.1 Model Equations. .... .... .... .... .... ..... .... 223
6.3.2 Simulation of the Riser in CFB Ozone
Decomposition... .... .... .... .... .... ..... .... 227
6.3.3 Simulation of the Downer in CFB Ozone
Decomposition... .... .... .... .... .... ..... .... 237
6.4 Summary .... .... ..... .... .... .... .... .... ..... .... 239
References. .... .... .... ..... .... .... .... .... .... ..... .... 240
7 Mass Transfer in Multicomponent Systems... .... .... ..... .... 243
7.1 Mass Transfer Rate in Two-Component (Binary) System.. .... 245
7.2 Mass Transfer in Multicomponent System .... .... ..... .... 251
7.2.1 Generalized Fick’s Law.... .... .... .... ..... .... 252
7.2.2 Maxwell–Stefan Equation .. .... .... .... ..... .... 252
7.3 Application of Multicomponent Mass Transfer Equation .. .... 256
7.3.1 Prediction of Point Efficiency of Tray Column ... .... 256
7.3.2 Two-Regime Model for Point Efficiency
Simulation. ..... .... .... .... .... .... ..... .... 257
7.3.3 Example of Simulation .... .... .... .... ..... .... 261