Study On The Integration Of Crude Oil Distillation And Heat Exchanger Network System

Crude oil distillation is a process of major importance in the refining industry.The performance of crude oil distillation affects the product yield and quality ofpetroleum distillate, and has an influence on the economic benefits. And the crude oildistillation is the major energy-intensive unit in the refinery, its energy consumptionaccounts for about20%~30%of the total energy consumption in refinery. So theresearch of crude oil distillation unit has great significance.In this paper, the crude oil distillation unit in Dagang petrochemical company wasstudied. To reduce energy consumption and improve system energy efficiency andsystem profit, a synthetic optimization technique based on ASPEN PLUS processsimulation software was employed which considered product quality and systemenergy consumption comprehensively. The coupling relationship between crude oildistillation and heat exchanger network was investigated. The optimization andintegration between crude oil distillation, heat exchanger network and utility wasachieved while meeting required product qualities.Based on steady-state simulation of the existing process and comparison with theactual operating data, suitable rigorous model, convergence method and propertymethod were selected, and a rigorous simulation system was build which couldrepresent the actual operation condition accurately. The profile of temperature andvapor/liquid flow rate in the tower.was investigated. The pumparound duty and interreflux’s effect on product quality, product yield and heat recovery was analyzed. Areliable evaluation method was provided for the system integration.In this paper, based on the SCFrac shortcut model, particle swarm optimizationalgorithm and pinch technology, a systematic optimization approach whichconsidered the product profit and energy recovery simultaneously was presented. Thedistillation operating parameters’ effect on product quality, product yield and heatrecovery was analyzed. With the objective of maximum annual net profit, the optimalproduct yield distribution and operating parameters were obtained while meetingrequired product qualities. The optimization and integration between crude oildistillation and heat exchanger network was realized. By taking the results of shortcutmodel as the initial value, the rigorous simulation was carried out to verify the feasibility of the results, and the final optimal result was obtained. After optimization,the annual net profit of the4.5Mt/a crude oil distillation unit was increased by33.66M$/a.Based on the data of the actual streams, the heat exchanger network was designedby using pinch analysis, and two schemes were presented: multi-splitting heatexchanger network and two-splitting heat exchanger network. The operatingflexibility of the two schemes was considered and the performance of the twoschemes was compared with the existing heat exchanger network. The results showedthat the two schemes had better heat recovery performance and lower total annualcost.