页岩气返排液处理单效MVR系统性能分析

Performance Analysis of Mechanical Vapor Recompression System in Shale Gas Flow-back Liquid Treatment

取样检测西南地区某页岩气田三个处于不同返排期的返排液,其具有TDS高、溶解性物质以氯化钠为主等特点,提出采用单效机械蒸汽再压缩(MVR)系统浓缩返排液的技术方案。通过建立数学模型,计算分析了料液浓度、进料温差和传热温差对系统性能影响。结果表明,适当提高料液浓度,可以降低系统的换热面积和比耗功;进料温差和传热温差对系统性能的影响类似,减小温差可以降低比耗功,但系统总换热面积增加;该系统能效比高,具有良好的能量循环利用效果。

Three flow-back water samples during different operating periods from a shale gas field situated at southwest China were tested.The results indicated that flow-back liquid had a high TDS and most of the dissolved substances were sodium chloride.Therefore,a mechanical vapor recompression system applied to flow-back fluid treatment was proposed.The effects of feed concentration,feed temperature difference and heat transfer temperature difference to the thermodynamic performance were discussed through a mathematical model.The simulating results showed that raising the feed concentration could reduce heat-transfer area and the specific compressor power.The effects of feed temperature difference and heat transfer temperature difference were similar,decreasing temperature difference could reduce the specific compressor power,but it also could increase the total heat transfer area.The proposed system had an efficient COP and a well energy cycling performance.