Modelling, Validation, and Control of an Industrial Fuel Gas Blending System

Abstract In industrial fuel gas preparation, there are several compositional properties that must be controlled within specified limits. This allows client plants to use the fuel gas mixture without having to adjust and control the composition themselves. These properties are controlled by adjusting the volumetric flow rates of several inlet gas streams of which some are makeup streams (always available) and some are wild streams that vary in composition and availability (by-products of plants). The inlet streams need to be adjusted in the correct ratios to control all the controlled variables (CVs) within limits while minimising the cost of the gas blend. Furthermore, the controller needs to compensate for fluctuations in inlet stream compositions and total fuel gas demand (the total discharge from the header). This paper describes the modelling and model validation of an industrial fuel gas header as well as a simulation study of a Model Predictive Control (MPC) strategy for controlling the system while minimising the overall operating cost.