Study On Coolant Balance Of The Ethylene Plant

As the exploiting Of Daqing oilfield goes further , the amount of accompanying gas in crude (i.e wet nature gas)decreases. Thus the amount of nature gas liquid produced by nature gas liquid plant, which uses wet nature gas as a field decreases, and the light hydrocarbon from crude stabilization plant turns to heavier. This results in that the feedstock Of ethylene plant turns to heavier too, the plant can not suit the changed feedstock well, and it is hard to keep coolant of refrigeration system in balance. To solve this problem, there are two ways: one is to revamp the refrigeration system, and expand its capacity; the other is to reduce the consumption of coolant in the process with the refrigeration system kept unchanged, In this paper, Several revamping schemes of cold box section of Daqing ethylene plant, which is the main user of coolant of refrigeration System were compared. And revamping proposal to reduce the consumption of coolant, and lower the loads of ethylene, and propylene compressors was given.By comparing the vapour-liquid equilibrium and physical property data calculated with SRK BWRS PR property methods, and considering the fact that SRK property method was used in preliminary design by designer -Stone & WebSter International Projects Corporation,SRK property method is Selected to calculate the thermodynamics function.A process simulation software-ASPEN PLUS was used to build the models of cold box section and refrigeration system. The simulation results were compared with design data provided by S&W, and the models proved to be good.Based on the proved models, three selected revamping schemes of the flowsheet sections were simulated, and the power consumption and recycle flows of coolants were obtained. It provides reliable data for revamping of the plant.