SCR denitration intelligent ammonia spraying optimization method and system based on zone control and advanced control

Abstract

The invention discloses an SCR denitration intelligent ammonia spraying optimization method and system based on zone control and advanced control. The method comprises the steps that 1, based on running data, an inlet oxynitride concentration model is established; the model and currently collected running data are utilized to obtain a predicted value of the concentration of inlet oxynitride; 2, ammonia spraying amount under a current working condition is calculated according to the predicted value to be sent to an SCR denitration system as a feed-forward signal; 3, a deviation between a measured value of the concentration of outlet oxynitride and a set value is solved and then input into a self-adaptive PID controller to obtain an ammonia spraying amount feedback control signal and send the signal to the SCR denitration system; 4, the SCR denitration system controls the ammonia spraying amount of an SCR denitration reactor according to the ammonia spraying amount feed-forward signal and the ammonia spraying amount feedback control signal; the SCR denitration reactor is divided into a plurality of zones, and the SCR denitration system adjusts an automatic adjusting valve of each zone according to the smoke oxynitride concentration and smoke flow rate of the corresponding zone to control the ammonia spraying amount of the corresponding zone.

Description

technical field [0001] The invention belongs to the technical field of out-of-stock thermal power, and relates to an SCR (Selective Catalytic Reduction) denitrification intelligent ammonia injection optimization method and system, in particular to an SCR denitrification intelligent ammonia injection optimization method and system based on partition control and advanced control. Background technique [0002] At present, in order to achieve ultra-low emissions of nitrogen oxides, most coal-fired thermal power plants have installed SCR denitrification devices, using the CEMS system (flue gas online monitoring system) to collect the concentration of nitrogen oxides at the inlet and outlet, and then perform PID (proportion- Integral-derivative) feedback control. [0003] PID feedback control such as figure 1 As shown, the calculated value of the ammonia flow rate is (the measured value of the concentration of nitrogen oxides at the inlet - the measured value of the concentration...

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Problems solved by technology

[0006] 1. The concentration of nitrogen oxides at the inlet and outlet is measured by the CEMS system. The sampling pipeline of the CEMS system is relatively long, resulting in a large pure delay in measurement, and the measured value has a delay of 2-3 minutes;

[0007] 2. The existing CEMS system uses single-point sampling measurement, so the measurement data cannot represent the average concentration of the entire cross-section;

[0008] 3. PID control is adopted, and the PID parameters will not change after the initial setting. Therefore, when the operating conditions of the unit load change, the denitrification system is not adjusted in time, and excessive emissions are prone to occur;

[0009] 4. In order to ensure discharge standards, the operator of the power plant set the PID parameter setting value very low, resulting in excessive ammonia injection, large overshoot of the control system, and low system response rate

Due to the frequent changes of the flue gas flow field in actual operation and the influence of pipe clogging, if the branch pipes are not adjusted in time, it is easy to cause uneven ammonia injection

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