超低排放限值下烟气脱硫装置SO_(2)控制方案研究

The Control Algorithm of SO_(2) on Flue Gas Desulfurization Unit under Ultra-low Emission Limit

目前湿法烟气脱硫装置出口二氧化硫浓度控制多采用浆液pH值定值控制方案,该方案在超低排放限值下出现净烟气二氧化硫浓度波动大,监控数据超标的问题。以氨法烟气脱硫装置为研究对象,吸收塔塔底供氨与原烟气二氧化硫流量构成随动控制,塔顶供氨采用模糊PID控制。该方案有效解决了净烟气二氧化硫浓度波动大,监控数据超标的问题,同时氨逃逸浓度降低至6.5×10^(-6)。相比于pH值定值控制方案,液氨消耗量大大降低。

The SO_(2) concentration was controlled by the constant pH value control scheme in flue gas desulfurization unit, the outlet SO_(2) concentration fluctuated greatly and the value exceeded the ultra-low emission standard. This study took flue gas desulfurization device as the object, which used liquid ammonia as desulfurizer. The flow rate of ammonia at tower bottom changed with the flow rate of SO_(2) in original gas. The fuzzy PID control method was adopted for the ammonia supply at the top of the tower. The new scheme can effectively solve the problem of large fluctuation of SO_(2) concentration and over standard emission. Meanwhile, the concentration of ammonia not involved in the reaction was reduced to 6.0 ppm. Compared with the pH value control scheme, the liquid ammonia consumption of the unit was greatly reduced.