A control method for scr ammonia injection in power plants based on denitrification reaction kinetic equation

Abstract

The invention belongs to the field of thermotechnical automatic control, and particularly discloses a power station SCR (selective catalytic reduction) ammonia spraying control method based on a denitration reaction kinetic equation. The method specifically comprises the following steps: equally dividing an SCR system to n reaction areas and building a model, determining an unknown parameter of the model, so as to obtain a practical reaction model, forecasting for p moments in future according to a working condition parameter at a current moment, and through optimizing a performance index, acquiring an optimal ammonia spraying quantity change rate, after executing an ammonia spraying quantity in the next moment, repeatedly performing the above steps, so as to realize rolling optimization.According to the method, through building the reaction model and optimizing the performance index, the on-line rolling optimization to an ammonia spraying flow is realized, thereby the problems of great inertia and uncertainty of the SCR system are solved, the precision, speed and stable capacity of SCR ammonia spraying control are improved, and the problems that NOx discharge exceeds a standard or ammonia escapes are effectively avoided, and the method is particularly suitable for a set with frequently fluctuant load.

Description

technical field [0001] The invention belongs to the field of thermal automatic control, and more specifically relates to a power station SCR ammonia injection control method based on a denitrification reaction kinetic equation. Background technique [0002] In order to reduce the emission of nitrogen oxides, currently coal-fired power plants mainly use selective catalytic reduction technology (selective catalytic reduction, SCR) for control. The key to efficient and safe operation of the SCR denitrification system of power plant boilers is high-speed and precise ammonia injection control. Too little ammonia injection will lead to excessive NOx concentration at the outlet, while excessive ammonia injection will lead to ammonia escape and increase the formation of ammonium bisulfate. The air preheater is blocked, which endangers the safe production of the power plant. [0003] Under stable working conditions, parameters such as flue gas flow rate, flue gas temperature, and NO...

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Problems solved by technology

Frequent changes in unit load will lead to frequent and large changes in inlet NOx concentration, flue gas temperature, and flue gas flow rate, and the SCR denitrification system of power plant boilers has the characteristics of large inertia, so the existing ammonia injection control method is not competent, which will lead to outlet NOx The concentration fluctuates frequently, affecting the normal operation of the unit

[0004] Based on the above defects and deficiencies, there is an urgent need in this field to further improve the ammonia injection control method of the existing SCR denitrification system of power plant boilers, so as to avoid the problem of frequent fluctuations in outlet NOx concentration caused by the large inertia of the system

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