Retrofit of heat exchanger network based on exchanger reassignment and genetic algorithm (GA)

doi:10.16085/j.issn.1000-6613.2016-2349

Abstract

Abstract: In process industry,many existing heat exchanger networks have huge energy recovery potential due to the unreasonable network structure. Therefore,it is necessary to retrofit those heat exchanger networks. This paper combined the exchanger reassignment strategy with the stage-wise superstructure. The exchanger reassignment strategy was improved further to make full use of existing heat exchangers. Meanwhile,more economic option was chosen by comparing the additional heat transfer area cost and the new heat exchanger cost when an existing heat exchanger was reused,ensuring a lower investment cost under the same energy-saving. A MINLP (mixed integer nonlinear programming) model to retrofit the heat exchanger network was built based on the stage-wise superstructure. The model considered the tradeoff among the additional heat transfer area cost,the new heat exchanger cost and the utility saving by retrofit. The retrofit of heat exchanger network was solved by genetic algorithm(GA). In a case study,the utility cost was reduced more than 60% and the retrofit profit would be 1.49×10⁷$/a. The total annual cost of the retrofit network was 1.290×10⁷$/a,which was 31.2% and 9.2% lower than the literatures,respectively. The utility cost was 42.4% and 17.0% lower than the literatures. A better retrofit result was achieved by the method proposed in this work.

Key words: heat exchanger network, retrofit, genetic algorithm, reassignment strategy

摘要： 在过程工业中，现存的许多换热网络由于结构和工艺的不合理，存在较大的能量回收潜力，使得许多换热网络有改造的需要。本文结合了分级超结构模型和换热器再分配策略，并对现有换热器再分配策略做了进一步改进，充分利用现有换热器，而当再利用现有换热器时，对比新增面积费用和新增换热器费用的大小，选择较小的方案，使相同的改造效果下的投资费用最小化。基于分级超结构模型，建立了换热网络优化改造的MINLP数学模型，充分考虑改造后节省的公用工程、原有换热器增加面积的投资费用、新增换热器的投资费用；基于遗传算法求解得到优化改造的换热网络。案例研究表明，改造所得到的换热网络与原换热网络相比，公用工程费用的降幅超过60%，改造收益为1.49×10⁷$/a；年度总费用为1.290×10⁷$/a，比相关文献低31.2%和9.2%，公用工程费用也比文献节省了42.4%和17.0%，实现了更优的改造效果。

关键词: 换热网络, 改造, 遗传算法, 再分配策略

CLC Number:

TQ021.8

JIANG Ning, YU Hangsheng, HAN Wenqiao. Retrofit of heat exchanger network based on exchanger reassignment and genetic algorithm (GA)[J]. Chemical Industry and Engineering Progress, 2017, 36(08): 2830-2837.

蒋宁, 俞杭生, 韩文巧. 基于面积再分配和遗传算法的换热网络改造[J]. 化工进展, 2017, 36(08): 2830-2837.

References

[1] 英国石油公司.BP世界能源统计年鉴[R]. 2016. British Petroleum Co. Ltd.. BP satistical review of world energy[R]. 2016.
[2] 吴敏,肖武,贺高红.基于遗传/模拟退火算法考虑压降的换热网络优化改造[J].化工进展,2015,34(4):1171-1177. WU M,XIAO W,HE G H. Retrofit of heat exchanging net work considering pressure drop based on GA/SA[J]. Journal of Chemical Industry and Engineering Society of China,2015,34(4):1171-1177.
[3] LINNHOFF B,VREDEVELD D R.Pinch technology has come of age[J].Chemical Engineering Progress,1984,80(7):33-40.
[4] WESTERBERG A W.Synthesis in engineering design[J].Computers & Chemical Engineering,1989,13(4/5):365-376.
[5] BRIONES V,KOKOSSIS A.A new approach for the optimal retrofit of heat exchanger networks[J].Computers & Chemical Engineering,1996,20(96):S43-S48.
[6] TJOE T N,LINNHOFF B.Using pinch technology for process retrofit[J].Chemical Engineering,1986,93(8):47-60.
[7] CIRIC A,FLOUDAS C.A retrofit approach for heat exchanger networks[J].Computers & Chemical Engineering,1989,13(6):703-715.
[8] ZHU X X,ASANTE N D K.Diagnosis and optimization approach for heat exchanger network retrofit[J].AIChE Journal,1999,45(7):1488-1503.
[9] YEE T F,GROSSMANN I E.A screening and optimization approach for the retrofit of heat-exchanger networks[J].Industrial & Engineering Chemistry Research,1991,30(1):146-162.
[10] SORŠAK A,KRAVANJA Z.MINLP retrofit of heat exchanger networks comprising different exchanger types[J].Computers & Chemical Engineering,2004,28(1):235-251.
[11] JE?OWSKI J,BOCHENEK R,POPLEWSKI G.On application of stochastic optimization techniques to designing heat exchanger-and water networks[J].Chemical Engineering & Processing Process Intensification,2007,46(11):1160-1174.
[12] SREEPATHI B K,RANGAIAH G P.Improved heat exchanger network retrofitting using exchanger reassignment strategies and multi-objective optimization[J].Energy,2014,67(4):584-594.
[13] SREEPATHI B K,RANGAIAH G P.Retrofitting of heat exchanger networks involving streams with variable heat capacity:application of single and multi-objective optimization[J].Applied Thermal Engineering,2015,75:677-684.
[14] AKPOMIEMIE M O,SMITH R.Retrofit of heat exchanger networks without topology modifications and additional heat transfer area[J].Applied Energy,2015,159:381-390.
[15] AKPOMIEMIE M O,SMITH R.Retrofit of heat exchanger networks with heat transfer enhancement based on an area ratio approach[J].Applied Energy,2016,165:22-35.
[16] PAN M,BULATOV I,SMITH R.Improving heat recovery in retrofitting heat exchanger networks with heat transfer intensification, pressure drop constraint and fouling mitigation[J].Applied Energy,2016,161:611-626.
[17] YEE T F,GROSSMANN I E,KRAVANJA Z.Simultaneous optimization models for heat integration-Ⅰ. Area and energy targeting and modeling of multi-stream exchangers[J].Computers & Chemical Engineering,1990,14(10):1151-1164.
[18] YEE T F,GROSSMANN I E.Simultaneous optimization models for heat integration-Ⅱ. Heat exchanger network synthesis[J]. Computers & Chemical Engineering,1990,14(10):1165-1184.
[19] LUO X,WEN Q Y,FIEG G.A hybrid genetic algorithm for synthesis of heat exchanger networks[J]. Computers & Chemical Engineering,2009,33(6):1169-1181.
[20] LIU X W,LUO X,MA H G.Studies on the retrofit of heat exchanger network based on the hybrid genetic algorithm[J]. Applied Thermal Engineering,2014,62(2):785-790.
[21] LIU X W,LUO X,MA H G.Retrofit of heat exchanger networks by a hybrid genetic algorithm with the full application of existing heat exchangers and structures[J]. Industrial & Engineering Chemistry Research,2014,53(38):14712-14720.
[22] BOGATAJ M,KRAVANJA Z.An alternative strategy for global optimization of heat exchanger networks[J]. Applied Thermal Engineering,2012,43(5):75-90.
[23] PONCE-ORTEGA J M,SERNA-GONZ LEZ M,JIM NEZ-GUTI RREZ A. Synthesis of multipass heat exchanger networks using genetic algorithms[J]. Computers & Chemical Engineering,2008,32(10):2320-2332.
[24] LI G Q,LUO Y S,XIA Y,et al.Improvement on the simultaneous optimization approach for heat exchanger network synthesis[J]. Industrial & Engineering Chemistry Research,2012,51(18):6455-6460.
[25] CHEN L. Heat integrated crude oil distillation system design[D]. Manchester:University of Manchester,2008.
[26] ZHANG H B,RANGAIAH G P. One-step approach for heat exchanger network retrofitting using integrated differential evolution[J]. Computers & Chemical Engineering,2013,50:92-104.