某天然气处理厂乙烷回收装置换热网络优化研究

Optimization of Heat Exchange Network for Ethane Recovery Unit in a Natural Gas Processing Plant

目前国内运行的乙烷回收装置很少进行换热网络分析,导致乙烷回收系统中能量未综合回收利用。为了乙烷回收装置能够得到有效综合利用,针对某天然气处理厂乙烷回收装置进行换热网络优化分析,发现该乙烷回收装置换热网络跨夹点换热较多,流程有较大的优化空间。对乙烷回收流程中脱乙烷塔顶回流方式、脱甲烷塔底重沸器热源、脱丙丁烷塔塔底换热方式进行改进,并用Aspen Energy Analyzer软件进行模拟分析,发现整个流程跨夹点换热量减小,能耗降低11.2%,改进后乙烷回收装置较原乙烷回收装置功率降低了3393 kW。将乙烷回收装置脱丙丁烷塔进料与稳定轻烃换热,增设换热器,稳定轻烃物流通过与脱丙丁烷塔进料物流换热回收热量以后进入脱丙丁烷塔中部,使脱丙丁烷塔底重沸器热负荷降低了313 kW,循环水量减少29.09 m^(3)/h。

At present,the heat exchange network analysis is rarely carried out in ethane recovery units operating in China,resulting in the lack of comprehensive recovery of energy in ethane recovery systems.In order to achieve effective comprehensive utilization of the ethane recovery unit,an optimization analysis of the heat exchange network for the ethane recovery unit in a natural gas processing plant is carried out.It is found that the ethane recovery unit has a high amount of cross pinch points heat exchange in the heat exchange network,and there is significant space for optimization in the process.Through the improvement of the top reflux mode of the deethanizer,the heat source of the reboiler at the bottom of the demethanizer,and the heat transfer mode at the bottom of the depbutane tower in the ethane recovery process,the simulation analysis with Aspen Energy Analyzer software shows that the heat exchange across the pinch points of the whole process is reduced,and the energy consumption is reduced by 11.2%.The power of the improved ethane recovery unit is 3393 kW lower than that of the original ethane recovery unit.Heat exchange is carried out between the feed of the depbutane tower in the ethane recovery device and stable light hydrocarbon,and an additional heat exchanger is added.The stable light hydrocarbon flow entered the middle of the depbutane tower after heat exchange,and recovery heat with the feed flow of the depbutane tower.Thus,the heat load of the reboiler at the bottom of the depbutane tower is reduced by 313 kW,the amount of circulating water is decreased by 29.09 m^(3)/h.