基于[火用]分析方法的天然气脱氮工艺优化

为了进一步提高天然气脱氮工艺的生产能效,基于塔河油田的基础数据,利用HYSYS软件对提出的膨胀制冷+LNG辅助制冷多级分离脱氮工艺进行了模拟,对工艺主要设备[火用]进行了分析计算,确定了[火用]损的主要设备,并根据设备[火用]损的分布情况,对提出的脱氮工艺进行了优化。研究结果表明:①不同设备的[火用]损差别较大,冷箱1、入口压缩机及水冷器为本工艺的主要[火用]损设备,三者[火用]损占总设备[火用]损的73.1%;②综合设备[火用]损及[火用]效率分析,冷箱1[火用]效率优化空间较小,入口压缩机[火用]效率优化空间较大;③根据[火用]分析结果提出了进料气入口两级增压方案,根据压缩单元总[火用]损及[火用]效率确定了最优中间压力为1250 kPa;④在优化工艺最优中间压力下,入口压缩机[火用]效率提高到94%,各设备总[火用]损降低了6.3%,总[火用]效率提高到97.1%。

Optimization of natural gas denitrification process based on enthalpy analysis method

In order to further improve the energy efficiency of the natural gas denitrification process, based on the basic data of Tahe Oilfield, the proposed multi-stage separation and denitrification process of expansion refrigeration + LNG auxiliary refrigeration was simulated by HYSYS software, and the main equipments of the process was analyzed and calculated. The main equipments with exergy loss were determined, and the proposed denitrification process was optimized according to the exergy loss distribution of equipments. The results indicated that the exergy loss of different equipment is quite different, and the main equipments with exergy loss are the cold box 1, the inlet compressor and the water cooler, and the total exergy loss of them accounts for 73.1% of the total equipment exergy loss. According to the total equipment exergy loss and exergy efficiency analysis, the optimization space of the exergy efficiency of cold box 1 is small, and that of inlet compressor is large. Based on the exergy analysis results, a two-stage pressurization scheme for feed gas inlet is proposed, and the optimal intermediate pressure is determined to be 1,250 kPa according to the total exergy loss and exergy efficiency of compression unit. Under the optimal intermediate pressure of the optimized process, the exergy efficiency of the inlet compressor is increased to 94%, the total exergy loss of each equipment is reduced by 6.3%, and the total exergy efficiency is increased to 97.1%.