Paper A7 to the Institution of Mathematics and its Applications Symposium on Partial Differential Equations and distributed Parameter Control Systems, University of Warwick, England, 13th-16th July 1971.

S F Bush with P Sinclair.

Introduction

By far the most general technical problem in the operation of an industrial-scale chemical process is the optimisation of performance by selecting appropriate steady-state values of the manipulable variables. This is thus more truly a design than a control problem. An exception to this generalisation is provided by the class of vapour-phase hydrocarbon oxidative processes of which combustion and chlorination systems are notable sub-divisions. Here there are often genuine problems of (a) moving between steady-states without entering regions in which explosions or excessive degradation of product can occur, and (b) determining steady-states which are sufficiently stable in some sense.

A feature of these systems is that the reactions are exothermic and carried out in combustion chambers or reactors designed to permit or induce an internal feedback of material by means of which hot reacted gas is mixed with cool feed gas, diluting it and bringing it rapidly to reaction temperature. In the system referred to here, chlorine and hydrocarbon are premixed and enter the reactor in an entraining jet which induces the recirculation and which is also allowed to impinge on the walls of the reactor.