Predication control technology-based denitration control method and denitration system thereof

Abstract

The invention discloses a prediction control technology-based denitration control method and a denitration system thereof, and belongs to the fields of power station denitration systems and control methods thereof. The method and the system are designed to solve the problem of low ammonia utilization rate of present control methods. The prediction control technology-based denitration control method comprises the following steps: respectively obtaining the total ammonia spraying amount of every flue area and the respective ammonia spraying amount of every subarea through a predication control technology; and judging integral ammonia spraying or subarea ammonia spraying according to a comparison result of the concentration deviation of NOx at the inlet of an SCR reactor in every flue area and a preset value. The denitration system used for realizing the control method comprises a flue divided into two areas in the flue gas flowing direction, SCR reactors and an ammonia spraying device, and every flue area is divided into at least four subareas through guiding plates. The prediction control technology-based denitration control method can improve the ammonia utilization rate. The denitration system has the advantages of high working efficiency and low running cost.

Description

technical field [0001] The invention relates to a denitrification control method based on predictive control technology and a denitrification system adopting the control method. Background technique [0002] Thermal power coal-fired boilers will produce a large amount of nitrogen oxides (NO x ), nitrogen oxides are one of the main sources of air pollution, are toxic to humans and animals, and are one of the main causes of acid rain and acid fog. Therefore, SCR (selective catalytic Reduction method) denitrification device is of great significance. Based on this, the amount of ammonia injection and the control method of ammonia injection valve are also particularly important. [0003] The control of ammonia flow generally adopts a fixed molar ratio control method and a fixed outlet NO x Concentration control mode (feedforward + PID control scheme), these two kinds of control are control logics built on the basis of uniform flue gas flow field and ammonia gas mixing; in the a...

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Problems solved by technology

[0003] The control of ammonia flow generally adopts a fixed molar ratio control method and a fixed outlet NO x Concentration control mode (feedforward + PID control scheme), these two kinds of control are control logics built on the basis of uniform flue gas flow field and ammonia gas mixing; in the actual operation process, due to structural design problems, Fluctuations in load, changes in equipment operating conditions, and other factors, the flue gas flow field is uneven, resulting in a mismatch between the ammonia concentration at each ammonia injection point and the flue gas concentration, resulting in an increase in the amount of ammonia injection, which in turn leads to local ammonia The overall operation and management level of the SCR device is low due to excessive escape, which affects the safe operation of the air preheater and electrostatic precipitator, and increases the cost of equipment maintenance and operation

[0004] The above control methods mainly have the following problems: low utilization rate of ammonia gas and low SCR denitrification efficiency; the control method belongs to the extensive type and after-the-fact type; for the controlled objects with non-uniformity and long delay, the control quality is poor, and the amount of ammonia injected It is difficult to meet the requirements in real time and accurately in the formulation; the cost of the control system is high

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