SCR nitrogen oxide content prediction control method and system

Abstract

The embodiment of the invention discloses an SCR nitrogen oxide content predictive control method and system. The method and the system are used for solving the problems of large overshoot, long regulation time and difficulty in stabilization of an existing SCR control system of a coal-fired power plant. According to the technical scheme, a type-2 fuzzy logic system is adopted as a nitrogen oxide content model in the SCR process, type reduction operation of the type-2 fuzzy logic system is considered, and an NT method is adopted to overcome the time-consuming iterative process of a KM method; according to the model, model parameters can be updated in real time through a feedback correction technology, and the time-varying characteristic of SCR system parameters is overcome; and based on an SCR process nitrogen oxide content model approximated by a type-2 fuzzy logic system, a constraint generalized prediction controller is adopted to realize multi-step prediction and rolling optimization of the SCR process nitrogen oxide content, the problems of inertia and time lag of an SCR system are solved, and meanwhile, various process constraints of an actual SCR process are met. Ammonia spraying control is achieved through a DCS bias module, an original PI controller does not need to be replaced, engineering implementation is greatly facilitated, and meanwhile DCS safety is guaranteed.

Description

technical field [0001] The embodiments of the present application relate to the technical field of SCR in coal-fired power plants, and in particular to a method and system for predicting and controlling the content of nitrogen oxides in SCR. Background technique [0002] With the urgent need of environmental protection, coal-fired power plants adopt low-nitrogen technology to reduce the emission of nitrogen oxides, so as to meet the strict exhaust emission requirements. Among the low-nitrogen technologies, selective catalytic reduction (SCR) has attracted widespread attention due to its advantages such as high denitrification rate, compact structure, and low transformation cost. SCR is a post-treatment denitrification technology installed in the tail flue of the boiler to reduce the concentration of nitrogen oxides in the flue gas. During the nitrogen oxide degradation process, ammonia gas enters the tail flue through the ammonia injection grille and mixes with the nitrogen...

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Problems solved by technology

In addition, the denitrification process is also affected by uncertain disturbances such as flue gas temperature, flow rate, and catalyst activity, resulting in time-varying and uncertain parameters.

[0003] The above characteristics in the SCR denitrification process of coal-fired power plants make it difficult to achieve effective control

Although the PI controller has been most widely used in the SCR denitrification process of coal-fired power plants due to its simplicity and mature technology, the performance of the PI controller is far from meeting the requirements, resulting in the overshoot of the NOx concentration at the SCR outlet Large, long adjustment cycle, difficult to stabilize the problem

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