1000MW机组交叉限制动作原因及处理

Research on the Causes and Treatments of the Crossing Restriction in 1000MW Unit

直流炉对燃料、给水、风量的比例有着严格的要求,所以水—燃料比、风—燃料比平衡是锅炉稳定运行的基础,一旦失调将造成主、再热蒸汽温度的大幅变化或者燃烧不稳定,甚至造成锅炉严重超温、水冲击或炉膛爆炸事故的发生。为了保证这种平衡,在控制逻辑中增加了交叉限制回路,使锅炉输入量的变化不能超出预定的比率。本文以邹县电厂2×1000MW机组为例,详细阐述了5种交叉限制的控制逻辑、作用、原因、对机组的影响以及动作处理,避免机组参数大幅波动等不安全事件的发生。

Concerning the strict limits on the ratio of fuel, feedwater and air quantity for once- through boiler, the stable operation of boiler relies heavily on the balance of water - fuel ratio and air - fuel ratio, the lack of which will result in the sharp changes of main and reheat steam temperature or combustion instability, or even serious overheat of boiler, water shock or furnace explosion accidents. In order to maintain the stable balance mentioned above, a crossing restriction loop is introduced to the control logic to limit the changes of boiler input within the preset ratio. This paper, taking 2× 1000MW units in Zouxian Power Plant as an example, expounds the control logic, functions, causes, effects on units and handle actions of 5 crossing restrictions, which will prevent unsafe incidents as sharp variation of parameters from happening.