Openloop unstable reactors present probably the most interesting and challenging control problem in chemical engineering. They can occur when the reactions are exothermic and irreversible and when reactant per-pass conversion is not high so that there is “fuel” available in the reactor to cause a temperature runaway. An openloop unstable process cannot be operated without a feedback controller on automatic. In a typical CSTR process the reactor temperature is controlled by manipulating the flowrate of the cooling medium. Closedloop stability may be achieved if the reactor is designed with sufficient heat-transfer area. The temperature control loop exhibits “conditional stability” since the controller gain must lie inside some range of values whose span depends on the heat-transfer area selected in the design. The purpose of this paper is to demonstrate the critical design trade-off between heat-transfer area and dynamic controllability in openloop unstable CSTRs.

开环不稳定反应器可能是化学工程中最有趣和最具挑战性的控制问题。当反应放热且不可逆，并且反应物的单程转化率不高，从而导致反应器中存在“燃料”以致温度失控时，会发生反应。如果没有自动反馈控制器，则无法运行开环不稳定过程。在典型的CSTR工艺中，通过控制冷却介质的流量来控制反应器温度。如果反应器设计成具有足够的传热面积，则可以实现闭环稳定性。温度控制回路具有“条件稳定性”，因为控制器增益必须在一定范围内的值内，该范围的跨度取决于设计中选择的传热面积。