Analysis of Control Strategies for Gas Boiler Flue Gas Return Modification

With the increasingly stringent requirements for energy saving and environmental protection, it has become an inevitable trend for gas boilers around the world to be retrofitted with nitrogen reduction. In this paper, the combustion process of the boiler is precisely regulated by adopting the flue gas return control strategy in order to realize effective nitrogen reduction retrofit. Through detailed analysis of natural gas, air and their reactant compositions, combined with the design conditions of the boiler, the effects of regulating the circulating air volume and boiler load on the thermal efficiency and nitrogen oxide ($\text{NO}_{\mathrm{x}}$) concentration of the boiler are investigated. The simulation results show that reasonable adjustment of the return airflow and boiler load can effectively improve the thermal efficiency of the boiler and reduce $\text{NO}_{\mathrm{x}}$ emissions. The study provides practical guidance based on the optimization of control strategy for the flue gas external recirculation nitrogen reduction retrofit, which has important reference value.