制氢装置开停工运行过程优化

Optimization of start-up and shutdown process in hydrogen production unit

针对中国石油兰州石化公司炼油厂5万m^3/h制氢装置开停工过程中废气排放量较大且排放时间较长的问题,采取了调整工艺操作步骤、优化开停工方案等措施。结果表明:在开工过程中,采取将先2.0 MPa氮气气密调整为先0.4 MPa氮气气密,利用火炬与燃料系统将置换废气排入60 m高空,在氢气质量调整阶段提前回收解吸气等操作,使装置开工时火炬排放时间缩短了6 h,火炬排放总量下降39 000 m^3,同时节约了20 000 m^3的氮气用量;在停工过程中,采取将造气和变压吸附系统调整为串联置换,切断装置进料前通过系统降压将氢气回收至1.3 MPa管网,调整解吸气火嘴切换降低解吸气排放量等操作,使装置停工时火炬排放时间缩短了6 h,火炬气排放总量下降30 000 m^3,同时节约了4 000 m^3的氮气用量。

Based on the problem of the large amount and the long time of exhaust gas emission in the 50 000 m^3/h hydrogen production unit during the start-up and shutdown period in the refinery of Lanzhou Petrochemical Company, PetroChina, the several measures were taken, such as adjusting process operation steps and optimizing start-up and shutdown schemes were taken. The results showed that after taking the countermeasures in the start-up, including adjusting the nitrogen gas sealing from 2.0 to 0.4 MPa, discharging the replaced flue gas to 60-meter high altitude via torch and fuel system, recycling the desorbed gas ahead of the hydrogen quality adjustment stage, the torch discharge time was shortened to 6 h, the total torch discharge amount was reduced by 39 000 m^3, and the nitrogen consumption was saved by 20 000 m^3;after taking the steps in the shutdown, such as adjusting the gas-making and pressure-switching adsorption system into the series-type replacement, recovering the hydrogen to 1.3 MPa pipeline network through system depressurization before stopping feedstock, adjusting the desorption nozzle switch to reduce the desorption discharge, etc, the discharge time of the torch was shortened to 6 h, the total torch discharge amount was reduced by 30 000 m^3,and the nitrogen consumption was saved by 4 000 m^3.