Optimization of ammonia injection control in the SCR system of coal-fired power stations for ammonia production by urea hydrolysis
Aims:This paper aims to optimize the control scheme of ammonia injection branch pipes of the SCR system of coal-fired power stations under urea hydrolysis to produce ammonia with its application effect analyzed.Methods:The urea hydrolysis system based on Aspen Plus was simulated;and the ammonia change characteristics were analyzed.The ammonia injection control optimization of the SCR system was completed in combination with engineering applications;and a targeted evaluation scheme to analyze the control optimization effect was established by using the actual operation data before and after the commissioning.Results:The simulation found that the reaction temperature,reaction pressure,and urea feed mass fraction all helped to increase the volume fraction of ammonia in the product gas.After the optimization of the ammonia injection control of the SCR system,the operating parameters of the SCR system before and after the commissioning of the two periods of time were selected for analysis.Through the calculation of the average ammonia consumption rate of the SCR system it was found that the average ammonia consumption rate of the SCR system decreased by 28.13% compared with that of the pre-commissioning after the commissioning of the SCR system,and the average ammonia consumption rate decreased by 30.27% after the commissioning of the SCR system compared with the average ammonia consumption rate of the SCR system in the two periods of time under the same evaporation rate of the boiler and the same concentration of the inlet NOx.Comparing the average ammonia consumption of the same boiler evaporation rate and the inlet NOx concentration during the two operation periods,it was found that the average ammonia consumption after commissioning was 30.27% lower than that before commissioning.Conclusions:The optimized control scheme of ammonia injection in the SCR system of coal-fired power stations with ammonia hydrolysis from urea can improve the denitrification performance of the unit and reduce the ammonia consumption of the system.
urea hydrolysis systemSCR systemammonia injection optimizationchemical reactionammonia-nitrogen mixing equivalent ratio
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