指導教授：吳哲夫臺灣大學：化學工程學研究所蘇乾元Su, Chien-YuanChien-YuanSu2014-11-252018-06-282014-11-252018-06-282014http://ntur.lib.ntu.edu.tw//handle/246246/261163近年來由於對環境保護意識的逐漸重視，在自然環境中遇熱可分解的環保素材如環保乳膠手套等環保物質在現今越來越受到重視。而環保乳膠手套正是乳酸的聚合產物，因此乳酸的需求也因此逐年增加，乳酸有兩種形式，L型和R型，其中L型的乳酸可以製造出較高品質的乳膠產品。 由於乳酸的傳統製程是必須透過發酵反應，而製程中其中會含有許多的雜質和未反應的原料有待分離，因此乳酸純化的議題近年來也越來越受到重視，純化方式有很多種，例如：分離方式加入熟石灰再經過過濾或是加入溶劑做萃取分離或是利用電極吸引分離，但是都會有乳酸回收率不高或是總處理量不大的缺點。因此利用乳酸與醇類的酯化以及乳酸酯與水的水解反應來純化乳酸具有高的處理量以及較高的乳酸回收率等優點。 本研究針對粗乳酸的純化製程做出設計，利用五種不同的醇類來設計此純化製程，並透過年總成本來選擇最經濟的純化製程，結果顯示甲醇以及丁醇有最少的年總成本，兩者會依據不同的回償年限而改變兩者的排名。 接下來針對甲醇以及丁醇系統的最適化穩態流程做控制架構的設計以及控制性能的測試。其中，控制架構以溫度控制以及組成控制為主，最後也嘗試串級控制，並且將原本的最適化的穩態架構做推廣，將水回流接上以期能夠有更好的能源運用。結果顯示甲醇系統的控制效果優於丁醇系統，可在較短的時間內達到新的穩態結果:甲醇的控制架構能通過流量正負10%以及乳酸5%以及重成分雜質3%的進料組成的擾動;丁醇的控制架構能通過流量正負10%以及乳酸5%以及重成分雜質3%的進料組成的擾動。Process designs for the continuous recovery of lactic acid from fermentation broth by reactive distillation (esterification and hydrolysis with C1 to C4 alcohols) are developed and optimized to minimize cost. The best designs are qualitatively different for different alcohols because of differing volatility ranking of reactants and products and the formation of a two liquid phase zone in some cases. The results suggest that the methanol and butanol processes are the most attractive solution. The costs of these two processes are similar, and the ranking depends on the payback period (when payback period is 3 butanol is more economical, vise versa). The ethanol and isopropanol processes are more expensive because an entrainer is required to break the alcohol/water azeotrope. Control structures for the methanol and butanol processes are designed and tested for the performance through feed flowrate, lactic acid composition and impurity composition disturbances. Designed control structures can be separated into 2 scenarios. One is 1-recycle stream of recovered alcohol. Another one is 2-recycle streams with recovered alcohol and water. Methanol system can implement 2 recycle streams and butanol system can implement 1 recycle stream. Results show that 1-recycle scenario is more robust than 2-recycle scenario because it has a more straight forward flowsheet. Combined composition and temperature control structures can handle more disturbances and maintain the constraints. Both methanol and butanol control structures can pass flow rate and composition disturbances. Methanol control structure is more robust than butanol control structure because it can handle the disturbances in less time.Contents 誌謝 i 中文摘要 iii Abstract iv List of Figures ix List of Tables xiv 1 Introduction 1 1.1 Review of lactic acid 1 1.2 Review of reactive distillation 5 1.3 Literature survey 7 1.4 Research motivation 9 1.5 Dissertation organization 10 2 Steady state flowsheet design 12 2.1 Process block description and design variables 12 2.2 Design procedure and objective function 18 2.3 Thermodynamics properties 22 2.4 Reaction kinetics 28 2.5 Pretest of conventional and reactive distillation configuration 33 3 Optimal steady state flowsheet result 36 3.1 Methanol system 36 3.2 Ethanol system 42 3.3 Isopropanol system 48 3.4 Butanol system 54 3.5 Pentanol system 60 3.6 Discussion and conclusion 67 4 Control structure design procedure 70 4.1 Methanol system temperature control structure 73 4.1.1 MCS1:Methanol 1-Recycle temperature control structure 82 4.1.2 MCS2:Methanol 1-Recycle composition control structure 89 4.1.3 MCS3:Methanol 2-Recycle temperature control structure 97 4.1.4 MCS4:Methanol 2-Recycle composition control structure 106 4.1.5 MCS5:Methanol 1-Recycle Cascade control structure 114 4.1.6 Summary and remarks 123 4.2 Butanol system control structure 125 4.2.1 BCS1 Butanol 1-Recycle Temperature control structure 132 4.2.2 BCS2 Butanol 1-Recycle composition control structure 140 4.2.3 BCS3 Butanol 2-Recycle temperature control structure 148 4.2.4 BCS4 Butanol 2-Recycle composition control structure 156 4.2.5 Summary and remarks 163 5 Conclusions 164 6 References 166 Appendix A: TAC Calculation Formula 172 Appendix B: UniQuac binary parameters 175 Appendix C: Inventory Control loop parameters 183 List of Figures Fig. 1 1 Conventional manufacture process for lactic acid from carbohydrate2 2 Fig. 1 2 Typical reactive distillation column. 5 Fig. 1 3 proposed process for recovery of lactic acid using methanol19 8 Fig. 1 4 proposed process for recovery of lactic acid using Butanol25 8 Fig. 2 1 Process block flow diagram 12 Fig. 2 2 three different esterification column configurations. 15 Fig. 2 3 vapor-liquid experiment data fitting curve: 26 Fig. 2 4 Liquid-Liquid envelope and azeotropic points for four systems. 27 Fig. 2 5 conventional methanol esterification reaction process 33 Fig. 3 1 Process flowsheet for methanol system 38 Fig. 3 2 Different design variable value effect on TAC of methanol system 40 Fig. 3 3 Optimal temperature and composition profile in methanol esterification column 41 Fig. 3 4 Optimal temperature and composition profile in methanol hydrolysis column 41 Fig. 3 5 Process flowsheet for ethanol system 44 Fig. 3 6 Different design variable value effect on TAC of ethanol system 46 Fig. 3 7 Optimal temperature and composition profile in ethanol esterification column 47 Fig. 3 8 Optimal temperature and composition profile in ethanol hydrolysis column 47 Fig. 3 9 Process flowsheet for isopropanol system 49 Fig. 3 10 Different design variable value effect on TAC of isopropanol system 52 Fig. 3 11 Optimal temperature and composition profile in isopropanol esterification column 53 Fig. 3 12 Optimal temperature and composition profile in isopropanol hydrolysis column 53 Fig. 3 13 Process flowsheet for butanol system 55 Fig. 3 14 Different design variable value effect on TAC of butanol system 57 Fig. 3 15 Optimal temperature and composition profile in butanol esterification column 58 Fig. 3 16 Optimal temperature and composition profile in butanol hydrolysis column 58 Fig. 3 17 Liquid-liquid envelope comparison between n-pentanol and butanol 60 Fig. 3 18 Process flowsheet for pentanol system 63 Fig. 3 19 Optimal temperature and composition profile in pentanol esterification column 65 Fig. 3 20 Optimal temperature and composition profile in pentanol hydrolysis column 65 Fig. 4 1 Sensitivities of tray temperatures for ±0.1% manipulated variables changes in preconcentrator 75 Fig. 4 2 Sensitivities of tray temperatures for ±0.1% manipulated variables changes in esterification column 75 Fig. 4 3 Sensitivities of tray temperatures for ±0.1% manipulated variables changes in hydrolysis column 76 Fig. 4 4 Sensitivities of tray temperatures for ±0.1% manipulated variables changes in recovery column 76 Fig. 4 5 Row sum of individual tray temperature for all 4 columns 77 Fig. 4 6 Methanol 1-recycle temperature control structure 81 Fig. 4 7 MCS1 ±10% flow rate disturbance dynamic response 83 Fig. 4 8 MCS1 ±5% lactic acid composition disturbance dynamic response 84 Fig. 4 9 MCS1 ±3% Impurity composition disturbance dynamic response 86 Fig. 4 10 MCS1 ±3% Impurity composition disturbance dynamic response 88 Fig. 4 11 Methanol 1-recycle composition control structure 90 Fig. 4 12 MCS2 ±10% flow rate disturbance dynamic response 91 Fig. 4 13 MCS2:±5% lactic acid composition disturbance dynamic response 93 Fig. 4 14 MCS2 ±3% Impurity composition disturbance dynamic response 95 Fig. 4 15 Methanol 2-recycle temperature control structure 98 Fig. 4 16 MCS3 ±10% flow rate disturbance dynamic response 99 Fig. 4 17 MCS3 ±5% lactic acid composition disturbance dynamic response 101 Fig. 4 18 MCS3 ±3% Impurity composition disturbance dynamic response 103 Fig. 4 19 MCS3 ±3% Impurity composition disturbance dynamic response 105 Fig. 4 20 Methanol 2-recycle composition control structure 107 Fig. 4 21 MCS4 ±10% flowrate disturbance dynamic response 108 Fig. 4 22 MCS4 ±5% lactic acid composition disturbance dynamic response 110 Fig. 4 23 MCS4 ±3% Impurity composition disturbance dynamic response 112 Fig. 4 24 Methanol 1-recycle cascade control structure 116 Fig. 4 25 MCS5 ±10% flow rate disturbance dynamic response 117 Fig. 4 26 MCS5 ±5% lactic acid composition disturbance dynamic response 119 Fig. 4 27 MCS5 ±3% Impurity composition disturbance dynamic response 121 Fig. 4 28 Sensitivity of tray temperature for ±0.1% manipulated variables changes in preconcentrator 127 Fig. 4 29 Sensitivity of tray temperature for ±0.1% manipulated variables changes in esterification column 127 Fig. 4 30 Sensitivity of tray temperature for ±0.1% manipulated variables changes in Esterification-separation column 128 Fig. 4 31 Sensitivity of tray temperature for ±0.1% manipulated variables changes in Hydrolysis column 128 Fig. 4 32 Row sum of individual tray temperature for 4 columns 129 Fig. 4 33 Control structure of 1-recycle temperature control structure 131 Fig. 4 34 BCS1 ±10% Feed flow rate disturbance dynamic response 133 Fig. 4 35BCS1 ±5% lactic acid composition disturbance dynamic response 135 Fig. 4 36BCS1 ±3% Impurity composition disturbance dynamic response 137 Fig. 4 37 Control structure of 1-recycle composition control structure 139 Fig. 4 38 BCS2 ±10% Feed flow rate disturbance dynamic response 141 Fig. 4 39 BCS2 ±5% lactic acid composition disturbance dynamic response 143 Fig. 4 40 BCS2 ±3% Impurity composition disturbance dynamic response 145 Fig. 4 41 Control structure of 2-recycle temperature control structure 147 Fig. 4 42 BCS3 ±10% Feed flow rate disturbance dynamic response 149 Fig. 4 43 BCS3 ±5% lactic acid composition disturbance dynamic response 151 Fig. 4 44 BCS3 ±3% Impurity composition disturbance dynamic response 153 Fig. 4 45 Control structure of 2-recycle composition control structure 155 Fig. 4 46 BCS4 ±10% Feed flow rate disturbance dynamic response 157 Fig. 4 47 BCS4 ±5% Lactic acid composition disturbance dynamic response 159 Fig. 4 48 BCS4 ±3% Impurity composition disturbance dynamic response 161 List of Tables Table 1 1 Lactic acid purification methods comparison 4 Table 2 1 Four systems optimal design specifications and design variables. 17 Table 2 2 Prices for alcohols and entrainers. 20 Table 2 3 Sources of binary interaction parameters. 24 Table 2 4 Ranking of azeotropic Temperatures and Pure Component NBP Temperatures 25 Table 2 5 Kinetic equations for four esterification reactions 31 Table 2 6 Kinetic equations for lactic acid oligomerization reactions 32 Table 2 7 TAC comparison between conventional and reactive distillation 34 Table 3 1 MeOH system optimal flowsheet design result 39 Table 3 2 Ethanol system optimal flowsheet design result 45 Table 3 3 iPrOH system optimal flowsheet design result 50 Table 3 4 BuOH system optimal flowsheet design result 56 Table 3 5 AmOH system optimal flowsheet design result 64 Table 3 6 Process TAC comparison 68 Table 3 7 TAC of methanol and butanol process sections for different payback periods 69 Table 4 1 Controlled variables, manipulated variables and relative gain array for four columns in methanol system 79 Table 4 2 Controlled variables, manipulated variables and relative gain array for four columns in butanol system 1303638679 bytesapplication/pdf論文公開時間：2016/07/22論文使用權限：同意有償授權(權利金給回饋學校)乳酸純化反應蒸餾最適化流程動態控制thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/261163/1/ntu-103-D96524019-1.pdf