关键词: 系统工程, 过程系统, 控制, 催化裂化, 多稳态

Abstract: Analyses of multiple steady states of a fluid catalytic cracking unit (FCCU) with high-efficiency regenerator with the riser reaction temperature under open loop and closed loop control were performed based on the theory of output multiplicity and input multiplicity. The multiple steady states under these two conditions were determined with respect to the amount of the added CO combustion promoter. The heat removal curve was found monotonously increasing with riser reaction temperature under open loop control, which resulted in the existence of three multiple steady states because of weak coupling between regenerator temperature and riser reaction temperature. On the other hand, the heat feedback of regenerator and riser reactor changed under closed loop control because regenerated catalyst flow rate could be used as an extra measure to compensate the difference between regenerator temperature and riser reaction temperature to enhance coupling between regerator temperature and riser reactor temperature. Multiple steady states would exist only when CO promoter was extremely insufficient. Otherwise, only one steady state existed under current operating condition which avoided multiple steady states with riser reaction temperature under open loop control.

Key words: systems engineering, process systems, control, FCCU, multiple steady states