高含氮天然气液化工艺的探讨

摘要

The natural gas with high content of nitrogen has the low combustion heat and large energy consumption in the oil - gas gathering and transportation. In order to remove the redundant nitrogen gas, a natural gas liquefaction process with cryo - denitrification was brought forward. The effects of raw natural gas＇properties, refrigerants＇properties, denitrification degree and the rectification pressure on the energy consumption were simulated and analyzed using the software of HYSYS. The optimization of operating conditions showed that when the pressure and temperature of refrigerants and natural gas were 0.4MPaG and 35℃, 2.6 MPaG and 20℃ respectively and the column pressure was 0.6MPaG, the energy consumption of the liquefied unit was least （ 0. 527 kW/Nm3 ）. The designed process provided important reference for the natural gas liquefaction with high -content nitrogen.%在不同气源中，含氮量较高的天然气热值低、集输过程中能耗大，为脱除天然气中过高含量的氮气，设计了深冷脱氮的天然气液化工艺。利用过程系统软件HYSYS模拟了深冷脱氮及液化天然气的过程，并分析了原料天然气特性、制冷剂特性及精馏塔操作条件对液化单元能耗的影响，对工艺条件进行了优化。结果表明，在制冷剂循环压力和温度为0．4MPaG和35℃，原料天然气压力和温度分别为2．6MPaG和20℃．精馏塔压力为0．6MPaG，氮气所占比例为0．5时，该液化单元的功耗最小，为0．527kW／Nm2，该工艺模拟和优化为高含氮气源进行液化利用提供了重要的参考。