Abstract: An autoacceleration control for a catalytic hydrocracker wherein, by means of a model of the reactor, there is generated a signel predicting the reaction temperature and means under the control of the signal adjusting the rate of application of a corrective agent to thereby inhibit auto acceleration of the hydrocracker.

Abstract: A proportional plus integral plus differential (PID) controller containing an algorithm option is disclosed. The option allows the selection of a classical interacting type of controller or a non-interacting type of controller. The classical interacting type of controller is characterized by the property that tuning any one of the proportional, integral or derivative terms changes the effective value of the other terms. In contrast, the non-interacting type of controller is characterized by the property that tuning any one of the proportional, integral or derivative terms has no effect on the other terms.

Abstract: A control logic system for updating physical property correlations. The difference between the calculated valve of a physical property and the laboratory value of the physical property is determined and combined with the previously determined value of the difference to obtain a new value of the correlation bias. Actuation of remote switches by the system operator allows this new value of correlation bias to pass through the control system and be "set" until an updated correlation bias is desired by the operator.