Ammonia desulfurization optimization control method based on multivariable predictive control

Abstract

The invention discloses an ammonia desulfurization optimization control method based on multivariable predictive control. Firstly, the overall ammonia desulfurization system is regarded as a two-in-two-out multivariable object, and the augmented state space model is obtained through identification; then, in combination of multivariable constrained predictive control and interval control, intake ammonia flows in an absorption section and an oxidation section of a desulfurization tower are controlled, and the SO2 concentration after desulfurization and the pH value of circulating slurry are guaranteed to be maintained in a given interval range. Through adopting the multivariable constrained predictive control method based on interval characteristics, the sensitivity to model errors is weakened, the robustness of the controller is enhanced, distribution of the intake ammonia flow in different reaction stages of the desulfurization tower can be better realized, coordination control demands are reduced on the premise of ensuring the desulfurization efficiency, the dynamic adjustment quality of the system is improved, the actuating frequency of an actuator is reduced, the ammonia consumption amount is reduced, and economic and environmental friendly operation of the desulfurization system is further promoted.

Description

technical field [0001] The invention belongs to the field of thermal automatic control, in particular to an ammonia desulfurization optimization control method based on multivariable predictive control. Background technique [0002] Flue gas ammonia desulfurization is a relatively new environmental protection technology. Although it has many incomparable advantages over other desulfurization methods, it also faces many problems: ammonia is a dangerous product. If the amount or method of ammonia addition is improper, It will cause secondary pollution and affect desulfurization efficiency; increasing the concentration of ammonia in the absorbent will help improve desulfurization efficiency, but at the same time it will also increase the amount of ammonia escape; supersaturation of the concentrated solution will not be conducive to SO 2 Absorption and easy crystallization to block the device; the mutual coupling between variables is a typical multivariate constraint process. T...

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Problems solved by technology

[0002] Flue gas ammonia desulfurization is a relatively new environmental protection technology. Although it has many incomparable advantages over other desulfurization methods, it also faces many problems: ammonia is a dangerous product. If the amount or method of ammonia addition is improper, It will cause secondary pollution and affect the desulfurization efficiency; increasing the ammonia concentration of the absorbent is beneficial to improve the desulfurization efficiency, but at the same time it will also increase the amount of ammonia escape; supersaturation of the concentrated solution will not be conducive to SO 2 absorption and easy to crystallize to block the device; the variables are coupled with each other, which is a typical multivariate constraint process

In this case, the traditional PID control scheme cannot solve the contradiction between the stability and quality of the control system at all, and it will inevitably cause instability and oscillation of the control system, which will cause repeated fluctuations in desulfurization efficiency

Especially in the process of changing load, the limited control effect will directly affect the desulfurization efficiency, and also lead to ammonia slip and aerosol

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