级联式天然气液化工艺能耗优化

Optimization of energy consumption of natural gas cascading liquefaction process

以脱酸、脱水、脱汞等净化处理后的天然气为原料,丙烷、乙烯和甲烷为制冷剂,采用级联式制冷工艺,利用HYSYS软件建立了天然气液化工艺流程模型。以单位能耗为流程优化的目标函数,各制冷循环的制冷剂压力、温度和循环量作为决策变量,并设定相关约束条件,对液化工艺能耗进行了优化。结果表明:在优化操作条件下,单位能耗为1 301 k J/m^3,压缩机总功耗为90.37 MW,二者分别低于优化前;随着天然气处理量的增加,压缩机功耗增加;当CH_4摩尔分数较高时,功耗相对较低;C_2H_6摩尔分数较高时,功耗相对也较高;N_2摩尔分数较高时,功耗变化不明显。

The natural gas liquefaction process model using a cascade refrigeration technology was established by HYSYS simulation software with natu- ral gas of deacidification, dehydration and demercu- ration as raw material, and propane, ethylene and methane as the refrigerants. Energy consumption of liquefaction technology was optimized with unit ener- gy consumption as objective function for optimizing process, refrigerant pressure, temperature and cycle refrigeration amount as decision variables, and the relevant constraints were set. The results showed that under the optimized conditions, the unit energy con-sumption was 1 301 kJ/m^3 ,and the total power con- sumption of compressor was 90.37 MW,which were lower than optimization before;the power consump- tion of compressor increased with the rising of natu- ral gas processing; when the mole fraction of CH4 was higher, the power consumption was relatively lower;when the mole fraction of C2H6 was higher,it was comparatively higher; when the mole fraction of N2 was higher,it did not change significantly.