| Heat Exchanger Network(HENS)is an important subsystem of energy recovery process in a chemical production.The retrofit of heat exchanger network is how to improve a heat exchanger network with a certain structure or operated and makes it to be optimal while the flows and the inlet and outlet temperatures of steams are changed and the heat exchanger network can also meet the technological demand and operation under the optimum condition or close to optimum.Optimal heat exchanger network structure,a comprehensive integration device can avoid the overall low heat with heat exchange network and the phenomenon of low thermal useless,solve all increase in the amount of hot and cold utilities unreasonable energy-using status,break down the entire network are optimized by the coordinating the bottleneck of low temperature heat recovery.This paper separately provides critical reviews of the literature on synthesis of heat exchanger net(HENS),optimal analysis of HENS,optimal design of heat exchangers,optimal simulation of HENS.The contents,methods as well as the chronological milestone in the development of these methods are presented.The heat-exchanger network to 2.5million tons/year atmospheric and vacuum plant oil refinery factory were analyzed and diagnosed by the use of HENS.At last,the whole captial cost and benefit were calculated,the cost and payback period were also listed.In this paper,based on the heat exchanger network software package(HENS),synthesis,analysis,optimal design of heat exchangers and simulation of heatexchanger network to 2.5million tons/year atmospheric and vacuum plant oil refinery factory,some problems in the existing HENS are found out.After making synthesis of HENS,analysis of HENS,the methods are proposed for optimal design and process simulation of heat exchangers in optimally retrofitting existing HENS.The leaving HENS temperature of the oil from the bottom of the initial column is risen form 284? to 306?.The fuel oil saved directly is 12 719.39 tons per year,benefit of energy saving is 61 180 300 yuan per year,gaining great benefit of energy saving,which provides reliable technique bags to the plant.After the improved heat exchange network,the temperature reached the respective requirements,the heat recovery volume was greatly improved,and the original three-part heat exchange structure was utilized to reduce the investment in transforming the economy.Through the heat exchanger through accounting,improve the heat exchange unit heat exchange area and optimization of each shunt flow,eventually make the bottom oil in at the beginning of the temperature to 306 ?,after 12 sets of new heat exchanger,the equipment investment is 42.636 million yuan,the payback period is 8.26 months.Finally,the sensitivity analysis of the optimized heat exchange network,in normal working condition of each logistics flow,upper and lower limits as a benchmark,given logistics inlet temperature,outlet temperature and pressure of simulate logistics are within the scope of the target requirements,the optimized results show that the heat exchange network has good elasticity of operation,for 2.5 million tons/year oil heat exchange network of atmospheric and vacuum workshop energy-saving technological transformation provides the technical basis.Heat exchange network optimization should use more utilities,for all the utilities price differential,reasonable configuration utility system,makes the energy to meet use step by step,at the same time considering the device of the utility system and configuration and requirements.Application relaxation reduce network investment costs,and by removing heat load is small,not economic heat exchanger,and is not convenient to break up the logistics to improve its operability. |
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