ENERGY CONSERVATION IN REFINERY WASTE GAS INCINERATION

Abstract

New incineration process designs are based on integrating the incineration system with heat recovery section so that the energy liberated on incineration is used in complementing the heat load requirements.

The operation of such systems should allow sufficient flexibilities in order to cope with a variable pollution load and a variable demand of heat in the waste heat recovery unit; while keeping the temperatures of incineration and flue gases within the limit dictated by incineration requirements and by the tolerance of the material of construction of downstream units.

The purpose of this work is therefore to suggest a computer control system aiming at coordinating the control actions manipulating the various fuel inputs and internal process streams to satisfy the above requirements simultaneously.

A rigorous heat-balance based steady-state model is first developed to generate the relationship among the various disturbances and manipulated variables. The computer generated model results are correlated as simple equations suitable for on-line computations.

An on-line computer control algorithm is then suggested on the basis of the above derived correlations. The control strategy is based on the inclusion of a feed-forward control action in addition to conventional feedback controllers. The suggested algorithm takes into account the effects of pollutant rate, heat load disturbances, and the availability of alternative gaseous and liquid backup fuels.