富气乙烷回收工艺改进及能耗分析

Improvement of rich gas ethane recovery and energy consumption analysis

关键词:  乙烷回收  冷干气回汽流程(CRR)  带闪蒸的冷干气回流流程(CRR-FE)  部分气原料气过冷分离的冷干气回流流程(CRR-PS)  综合能耗分析  火用分析 

Key words:  ethane recovery  CRR  CRR-FE  CRR-PS  comprehensive energy consumption  exergy analysis

摘要:

目的 针对国内处理原料气在气质较富时乙烷回收装置单一、产物回收率低的问题,在原有工艺冷干气回流流程(cold residue reflux process, CRR)的基础上提出两种高效乙烷回收流程,即带闪蒸的冷干气回流流程(cold residue reflux process with flash evaporator, CRR-FE)和部分原料气过冷分离的冷干气回流流程(cold residue reflux process with feed subcooled, CRR-PS)。方法 在保证乙烷回收率高于95%的条件下,利用HYSYS软件模拟改进工艺流程,设置了3组逐渐变富的气质对CRR及改进流程进行了综合能耗和火用分析对比。结果 改进后的流程有很好的节能效果,其中CRR-PS流程节能效果明显,在GPM值为4.3时,CRR-PS流程综合能耗节约了9.4%。3种流程火用损最大为主体设备压缩机中的外输压缩机,其次是塔设备中脱甲烷塔和丙烷制冷,最后是换热器、空冷器及水冷器；改进后的流程性能很好,整体火用效率在80%以上,总火用效率排序为CRR-PS＞CRR-FE＞CRR；当GPM值为4.3时,CRR-PS火用损为28 471 kW,相比于CRR降低了3.9%,表明CRR-PS火用损失较少,有很好的节能潜力。结论 CRR-PS流程对富气适应性更强,节能效果更好。 

Abstract:

Objective Aiming at the problems of using single device and low recovery rate for ethane recovery process to the rich raw gas at home, based on the former cold residue reflux process(CRR), two efficient ethane recovery processes, namely cold residue reflux process with flash evaporator(CRR-FE) and cold residue reflux process with feed subcooled(CRR-PS) are proposed in this paper. Methods The simulation was improved by using HYSYS software under the condition that the ethane recovery rate was maitained higher than 95%. Three groups of progressively richer gas were set up to compare the CRR and the improved process with a comprehensive energy consumption and exergy analysis. Results The improved process has good energy saving effect, among which the CRR-PS has obvious energy saving effect, and the CRR-PS saves 9.4% of the integrated energy consumption when the gallons per minute(GPM) is 4.3. The three processes have the highest yield loss for the external compressor in the main equipment compressor, followed by the demethanization tower and propane refrigeration in the tower equipment, and then the heat exchanger, air coolers, water coolers; the improved process has a very good performance, and the overall exergy efficiency is higher than 80%, and the size of the total exergy efficiency is in the order of CRR-PS > CRR-FE > CRR; When the GPM is 4.3, the CRR-PS exergy losses are 28 471 kW, which is 3.9% lower compared to the CRR, indicating that the CRR-PS has less exergy losses and has a good potential for energy savings. Conclusion sThe CRR-PS is highly adaptable to rich gas and provides the better energy savings.