A new approach to construct dynamic models for NOx control in a FGR furnace

Abstract

This paper presents a new approach to construct dynamic models for NOx control of an industrial furnace with flue gas recirculation (FGR). In this paper, the full‐scale computational fluid dynamics (CFD) simulations are carried out for the FGR furnace and the CFD results are used to construct the transfer functions to represent the linearized dynamic models of the furnace. The controllers are then designed based on these models. Finally, the results obtained from full‐scale CFD simulation are used to validate the dynamic models. It is indicated that the dynamic models obtained by the new approach are capable of capturing the dynamic characteristics of the combustion system. The numerical simulation of the turbulent non‐premixed combustion process in the furnace is conducted using a moment closure method with the assumed – probability density function (PDF) for the mixture fraction. The combustion model is derived based on the assumption of instantaneous full chemical equilibrium. The discrete transfer radiation model is chosen as the radiation heat transfer model, and the weighted‐sum‐of‐gray‐gases model is used to calculate the absorption coefficient.