Modeling And Control Of A Reverse Flow Reactor For VOCs Catalytic Combustion

Volatile organic compounds (VOCs) are the main components of atmospheric pollutants. More and more attention has been paid to their purification. Although catalytic decomposition has always been considered as the best technology to purify VOCs with high flow rates and low concentrations, catalytic combustion of VOCs in a reverse flow reactor (RFR) has unique advantages from the point of view of efficiency and energy consumption. As the adiabatic temperature rises and the flow rate of the feed changes, the simple and efficient control strategies are essential to avoid both catalytic overheating and reaction extinction.Based on some acceptable assumptions, a heterogeneous one dimensional model taking account of axial dispersion in the beds of a RFR consisted of one catalyst bed in the middle and two inert beds has been proposed. The axial dispersion may be due to the movement of heat wave from the inlet to the outlet. The effects of the operation parameters, such as the packing structure of reactor, the fluctuation of concentration and the flow rate of VOCs on the performance of the reactor have been investigated. In this work, several temperature measuring points have been set in the highest temperature area of the reactor. The maximum temperature has been polynomial fitted and substituted as the maximum temperature solved by the model. A single point control scheme, as well as a direct control scheme, has been designed on the basis of the fitted maximum temperature. These two simple control schemes have been model validated and their adaptability and sensitivity to disturbance have been contrasted. The results show that the direct control scheme is better than the single point control scheme in terms of energy efficiency.