Separation of n-heptane/isobutanol via eco-efficient vapor recompression-assisted distillation: process optimization and control strategy
Wei Hou1, Qingjun Zhang1, Aiwu Zeng1,2()
1. State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China 2. Chemical Engineering Research Center, Collaborative Innovative Center of Chemical Science and Engineering, Tianjin 300072, China
In this study, vapor recompression and heat integration assisted distillation arrangements with either the low or high pressure in the reflux drum are proposed to reduce and/or eliminate the application of the costly refrigerant for the separation of n-heptane and isobutanol mixture. The high-pressure arrangement with vapor recompression and heat integration is the most attractive among these four intensified configurations since it can reduce total annual cost by 18.10%, CO2 emissions by 75.01% based on natural gas (78.78% based on heavy oil fuel), and second-law efficiency by 61.20% compared to a conventional refrigerated distillation system. Furthermore, exergy destruction in each component is calculated for the heat integration configurations and is shown in pie diagrams. The results demonstrate that the high-pressure configuration presents unique advantages in terms of thermodynamic efficiency compared to the low-pressure case. In addition, dynamic control investigation is performed for the economically efficient arrangement and good product compositions are well controlled through a dual-point temperature control strategy with almost negligible product offsets and quick process responses when addressing 20% step changes in production rate and feed composition. Note that there are no composition measurement loops in our developed control schemes.
. [J]. Frontiers of Chemical Science and Engineering, 2021, 15(5): 1169-1184.
Wei Hou, Qingjun Zhang, Aiwu Zeng. Separation of n-heptane/isobutanol via eco-efficient vapor recompression-assisted distillation: process optimization and control strategy. Front. Chem. Sci. Eng., 2021, 15(5): 1169-1184.
E Hu, Z Gao, Y Liu, G Yin, Z Huang. Experimental and modeling study on ignition delay times of dimethoxy methane/n-heptane blends. Fuel, 2017, 189: 350–357
2
R Danon, E Alhseinat, C Peters, F Banat. Solubility of heptane in aqueous solutions of methyldiethanolamine (MDEA). Fluid Phase Equilibria, 2016, 415: 18–24
3
M N A M Yusoff, N W M Zulkifli, H H Masjuki, M H Harith, A Z Syahir, L S Khuong, M S M Zaharin, A Alabdulkarem. Comparative assessment of ethanol and isobutanol addition in gasoline on engine performance and exhaust emissions. Journal of Cleaner Production, 2018, 190: 483–495
4
W L Magee. Method for preparation of alkyl vanadates. US Patent, 4351775, 1982-09-28
5
Y Wang, Z Zhang, D Xu, W Liu, Z Zhu. Design and control of pressure-swing distillation for azeotropes with different types of boiling behavior at different pressures. Journal of Process Control, 2016, 42: 59–76
6
Q Zhang, P Shi, W Hou, S Yang, A Zeng, Y Ma, X Yuan. Dynamic control analysis of an eco-efficient side-stream extractive distillation configuration. Separation and Purification Technology, 2020, 239: 116525
7
Z Feng, W Shen, G P Rangaiah, L Dong. Design and control of vapor recompression assisted extractive distillation for separating n-hexane and ethyl acetate. Separation and Purification Technology, 2020, 240: 116655
8
Y Wang, S Liang, G Bu, W Liu, Z Zhang, Z Zhu. Effect of solvent flow rates on controllability of extractive distillation for separating binary azeotropic mixture. Industrial & Engineering Chemistry Research, 2015, 54(51): 12908–12919
9
C Cui, S Liu, J Sun. Optimal selection of operating pressure for distillation columns. Chemical Engineering Research & Design, 2018, 137: 291–307
10
A Risco, V Plesu, J A Heydenreich, J Bonet, A E Bonet-Ruiz, A Calvet, P Iancu, J Llorens. Pressure selection for non-reactive and reactive pressure-swing distillation. Chemical Engineering and Processing-Process Intensification, 2019, 135: 9–21
11
X You, I Rodriguez-Donis, V Gerbaud. Low pressure design for reducing energy cost of extractive distillation for separating diisopropyl ether and isopropyl alcohol. Chemical Engineering Research & Design, 2016, 109: 540–552
12
W L Luyben. Distillation column pressure selection. Separation and Purification Technology, 2016, 168: 62–67
13
C Cui, J Sun. Rigorous design and simultaneous optimization of extractive distillation systems considering the effect of column pressures. Chemical Engineering and Processing-Process Intensification, 2019, 139: 68–77
14
Y Wang, P Qi, X Yang, Z Zhu, J Gao, F Zhang. Exploration of a heat-integrated pressure-swing distillation process with a varied-diameter column for binary azeotrope separation. Chemical Engineering Communications, 2019, 206(12): 1689–1705
15
W L Luyben. Design and control comparison of alternative separation methods for n-heptane/isobutanol. Chemical Engineering & Technology, 2017, 40(10): 1895–1906
16
Z Feng, W Shen, G P Rangaiah, L Lv, L Dong. Process development, assessment, and control of reactive dividing-wall column with vapor recompression for producing n-propyl acetate. Industrial & Engineering Chemistry Research, 2018, 58(1): 276–295
17
Q Li, Z Feng, G P Rangaiah, L Dong. Process optimization of heat-integrated extractive dividing-wall columns for energy-saving separation of CO2 and hydrocarbons. Industrial & Engineering Chemistry Research, 2020, 59(23): 11000–11011
18
M B Leo, A Dutta, S Farooq. Process synthesis and optimization of heat pump assisted distillation for ethylene-ethane separation. Industrial & Engineering Chemistry Research, 2018, 57(34): 11747–11756
19
W L Luyben. High-pressure versus low-pressure auxiliary condensers in distillation vapor recompression. Computers & Chemical Engineering, 2019, 125: 427–433
20
V Pleşu, A E Bonet Ruiz, J Bonet, J Llorens. Simple equation for suitability of heat pump sse in distillation. Computer-Aided Chemical Engineering, 2014, 33: 1327–1332
21
J M Douglas. Conceptual design of chemical processes. New York: McGraw-Hill, 1988, 289–315
22
M A Gadalla, Z Olujic, P J Jansens, M Jobson, R Smith. Reducing CO2 emissions and energy consumption of heat-integrated distillation systems. Environmental Science & Technology, 2005, 39(17): 6860–6870
23
M A Waheed, A O Oni, S B Adejuyigbe, B A Adewumi, D A Fadare. Performance enhancement of vapor recompression heat pump. Applied Energy, 2014, 114: 69–79
24
J D Seader, E J Henley, D K Roper. Separation Process Principles. Hoboken: John Wiley & Sons, Inc, 2010, 258–286
25
Q Zhang, M Liu, A Zeng. Performance enhancement of pressure-swing distillation process by the combined use of vapor recompression and thermal integration. Computers & Chemical Engineering, 2019, 120: 30–45
26
Q Zhang, S Yang, P Shi, W Hou, A Zeng, Y Ma, X Yuan. Economically and thermodynamically efficient heat pump-assisted side-stream pressure-swing distillation arrangement for separating a maximum-boiling azeotrope. Applied Thermal Engineering, 2020, 173: 115228
27
P Shi, Q Zhang, A Zeng, Y Ma, X Yuan. Eco-efficient vapor recompression-assisted pressure-swing distillation process for the separation of a maximum-boiling azeotrope. Energy, 2020, 196: 117095
28
S Yang, Q Zhang, Y Ma, X Yuan, A Zeng. Eco-efficient self-heat recuperative vapor recompression-assisted side-stream pressure-swing distillation arrangement for separating a minimum-boiling azeotrope. Industrial & Engineering Chemistry Research, 2020, 59(29): 13190–13203
29
W L Luyben. Distillation Design and Control Using AspenTM Simulation. Hoboken: John Wiley & Sons, Inc, 2013, 145–184
