燃煤机组烟气脱硫系统供浆控制策略研究与应用

Research and Application of Slurry Supply Control Strategy for WFGD System of Coal-fired Power Plants

为了有效控制火电厂SO_(2)排放浓度,满足超低排放要求,实现石灰石供浆量自动控制,针对现有的以吸收塔浆液pH值为被控量的石灰石供浆泵控制系统存在的抗扰动能力弱、控制效果差、自动化程度低等问题,提出了一种新型的以净烟气SO_(2)浓度为被控对象的石灰石供浆泵自动控制方案,创新性地引入在线计算的补偿修正系数对理论供浆量进行修正,以此作为供浆量的前馈信号,并引入模糊控制进一步提高控制质量,结合串级控制系统实现石灰石供浆泵的自动控制。最后,将所设计的控制策略应用于山西某电厂脱硫系统。运行结果表明:石灰石供浆泵自动控制系统能够长期稳定运行,降低了运行人员工作强度,实现了SO_(2)超低排放的自动控制,减少了人为因素导致的脱硫净烟气二氧化硫超标事故。

In order to effectively control the SO_(2) emission concentration of thermal power plants and meet the ultra-low emission requirements,automatic control of limestone slurry supply needs to be realized.The existing control system of limestone slurry pump which uses the pH value of the absorption tower slurry as controlled quantity has problems such as weak anti-disturbance ability,poor control effect,and low degree of automation.A new type of automatic control scheme for the limestone slurry supply pump with the concentration of the net flue gas SO_(2) as the controlled object is proposed.It innovatively introduces the compensation correction coefficient of online calculation to correct the theoretical slurry supply,using this as the feedforward signal of the pulp supply,and introduces fuzzy control to further improve control quality,which is combined with cascade control system to realize automatic control of limestone slurry pump.Finally,the designed control strategy is applied to the desulfurization system of a power plant in Shanxi.The operation results show that the automatic control system of the limestone slurry supply pump can operate stably for a long time,reduce the work intensity of the operators,realize the automatic control of ultra-low SO_(2) emissions,and reduce the accidents of excessive sulfur dioxide in the desulfurization flue gas caused by human factors.