SNCR脱硝系统的广义预测控制

Generalized Predictive Control on SNCR Denitration System

由于脱硝回路具有大滞后、强非线性等特点,热电锅炉基于PID控制器的脱硝回路自动控制系统存在控制品质差、自控投运率低等问题。分析了SNCR工艺流程特点及现有控制策略的不足,提出了一种基于广义预测控制算法的SNCR脱硝系统控制策略。针对回路特点改进控制策略,利用最小二乘法获得氨水阀门开度与氮氧化物质量浓度的一阶惯性纯滞后模型,使用广义预测控制算法控制氮氧化物质量浓度,在原有DCS的基础上设计并实现了SNCR脱硝回路先进控制系统。现场投运结果表明:基于广义预测控制的脱硝系统氮氧化物排放量波动幅度降低,回路自控投运率提高。

Due to the characteristics of large lag and strong nonlinearity of denitration loop, PID-based automatic control system of power plants owns poor control quality and low loop automatic operation rate for denitration loop. The characteristics of SNCR process and shortage of existing control strategy are analyzed with proposal of a new SNCR denitration system control strategy based on one generalized predictive control algorithm. Design and implement of advanced control system for SNCR denitration loop are realized on the basis of original DCS with improving control strategy focusing on loop characteristics, and first order inertia pure lag model with least squares method to obtain valve opening degree and nitrogen oxide mass concentration, and application of generalized predictive control algorithm to control nitrogen oxides mass concentration. The on-site operation results show fluctuation of nitrogen oxide emissions amount of denitration system is reduced and automatic control loop operation rate is increased for denitration system based on generalized predictive control.