Ammonia spraying amount controlling method for SNCR (selective no catalytic reduction) flue gas denitrating system for cement manufacturing

Abstract

An ammonia spraying amount controlling method for an SNCR (selective no catalytic reduction) flue gas denitrating system for cement manufacturing includes the steps of firstly, arranging at least two layers of ammonia spraying areas in a cement kiln decomposing furnace; secondly, arranging a temperature sensor, a glue gas flow detecting sensor and a first NOx concentration detecting sensor at an entrance of the ammonia spraying areas, and arranging a second NOx concentration detecting sensor and an NH3 concentration detecting sensor at an exit of the cement kiln decomposing furnace; thirdly, by the aid of an ammonia spraying amount controlling system which is provided with an ammonia spraying amount BP (back propagation) neural-network predicting model, giving a total ammonia spraying amount and an ammonia spraying amount proportion between each two layers of the ammonia spraying areas via the ammonia spraying amount BP neural-network predicting model according to received flue gas temperature information, flue gas flow information and concentration information of NOx in flue gas at an entrance of the cement kiln decomposing furnace and concentration information of the NOx in the flue gas and NH3 concentration information at the exit of the cement kiln decomposing furnace, and controlling states of a total ammonia flow adjusting valve and branch ammonia flow adjusting valves according to the total ammonia spraying amount and the ammonia spraying amount proportions among the layers of the ammonia spraying areas to achieve real-time controlling of the ammonia spraying amount.

Description

technical field [0001] The invention belongs to the technical field of flue gas denitrification in cement production, and in particular relates to a method for controlling the amount of ammonia sprayed in a selective non-catalytic reduction flue gas denitrification system in cement production. Background technique [0002] Currently, nitrogen oxides (NO X ) governance has become the top priority of my country's air pollution control. my country's cement production accounts for about 50% of the world's total. In recent years, it has shown a rapid increase trend. The annual new cement production accounts for more than 80% of the global new production. The NOx emitted by the cement industry X Accounting for about 10-12% of the total emissions, it is already the third largest NOx emitter after thermal power generation and vehicle exhaust. my country proposed in the "Twelfth Five-Year Plan" "Guiding Opinions on Energy Conservation and Emission Reduction in the Cement Industry" ...

AI Technical Summary

Problems solved by technology

However, it is difficult to overcome the nonlinearity and hysteresis of the system, and it is difficult to achieve real-time and accurate control of the amount of ammonia injection after the PID controller calculates and sends out the command of the opening degree of the regulating valve to control the flow of ammonia injection.

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