The Effects On Dynamic Characteristics And Heating Surface Absorption Of Low NO_x Combustion In Utility Boiler

In order to satisfy the new atmospheric pollutant emission standard, the transformation of low-nitrogen combustion has been carried out in most of the domestic utility boiler units currently. This technique can effectively reduce NOx emissions, but it brings some problems to boiler operation control,such as main steam pressure deviation becomes larger, reheat steam temperature becomes lower. Low NOx combustion transformation affect the unit coordinated control and operating parameters characteristic. But targeted research for this problem is still lacking. Therefore, further study of the static and dynamic characteristics of the boiler has important practical implications for low-nitrogen combustion burner operation control.In this paper, the operation conditions, heating surface absorption and dynamic characteristics of the unit before and after low NOx combustion transformation are studied. Firstly, on-site operating data are processed, and the steady-state operating parameters and heating surface absorption of the units under different operating conditions are obtained. According to the results of data fitting, combined with the design parameters, the operating law of the unit and the heat absorption law of heating surface are summarized. Then, the mathematical model of boiler system is set up based on the principle of mechanism analysis and lumped parameters, and the model is built on the Matlab/Simulink simulation platform. The simulation model has been verified by the variable load operation data, which proves its accuracy is high. Finally, the dynamic characteristics of the boiler are studied by using three typical load cases, such as 350MW,450MW and 550MW, as the initial steady state. Simulation results show that:in the same load lifting range, variation range of key parameters after the transformation is less than that of before. Unit operation seems easier to control, but if the unit control mode dose not chang, it will cause problems to the stable and secure operation of the unit.Combined operating data processing and analysis and dynamic modeling and simulation, multi-aspect studies on the performance of boiler before and after low NOx combustion transformation are conducted in this paper, which is also necessary for in-depth study of boiler operation rules and unit coordinated control optimization.