Prevention of Loss of Control in Chemical Plants under Computer Control

As the use of direct computer control in chemical plants increases, loss of control due to computer failure becomes a major concern. A fault tolerant computer control system is constructed and tested using a heat exchanger network. Redundancy and diversity are created both in hardware and software. Tolerance to sensor failure is created by control system reconfiguration. With reassignment of control duties, computer failure cause process upsets similar to temporary process disturbances. The magnitude and duration of upsets are closely related to the takeover time of the substitute computer.