催化裂化联合装置开停工不放火炬措施

The Measures for Zero Flare Emission in FCCU Startup/Shutdown

在装置低负荷下,气压机因入口流量不足,容易产生喘振。因此,在开工反应喷油15 min 内和停工切断进料后,气压机往往无法正常运行,需通过入口放火炬阀控制反应压力。镇海炼化通过不断实践,摸索出一套新的操作方法,解决了以往开停工过程中气压机组喘振的问题,实现了开、停工火炬零排放。该方法即停工时,在切断进料前预提升干气不提前切换成蒸汽,切断进料后引部分再吸收塔干气返回分馏塔,维持气压机运转,减少前部单元气体总量;开工时,反应喷油前气压机提前暖机,喷油后气压机升速时就将富气并入吸收-解吸系统,避免用入口放火炬阀控制反应压力。

In FCC unit under low-load operation, gas compressor surge was usually caused by insufficient inlet flow. Therefore, flare valve at the inlet of the compressor must be used to control the reactor pressure in 15 minutes after feed injection or after feed cut-off when the compressor was not in normal operating condition. Through continuous practices in ZRCC, a new method was found to solve the surge problem in previous startup/shutdown, and achieved zero flare emission. The main contents of the method were as follows: when shutdown, pre-lifting gas was not switched to steam before feed cut-off, and part of dry gas from re-absorption column, after feed cut-off, was led back to fractionating column to maintain the compressor at work and reduce the total amount of gas ahead of the unit;when startup, the compressor warm-up was got ready before feed injection, and rich gas was directly injected into absorption-desorption system with compressor accelerating after oil injection, which could avoid using flare valve to control reactor pressure.