Optimization of WFR strategy for ultra-supercritical units with high heating load

Abstract

A certain ultra supercritical unit has a rated load of 670mw and has been undertaking industrial steam supply for a long time, with a maximum steam supply of 500t / h. During the load change process of the unit, the main steam pressure and temperature fluctuate greatly, and the load regulation does not meet the requirements, so the unit cannot operate safely and stably. It is optimized from ratio of water quantity to coal quantity(WFR) strategy. The logic related to the correction of the intermediate point temperature on the fuel quantity is deleted. The position of the intermediate point is changed from the inlet of the primary superheater to the outlet of the steam water separator. The adjustment of the WFR through the intermediate point temperature is changed to the adjustment method based on the calculation of enthalpy value. The heating load is converted into electrical load and added to the boiler main control command. After optimization, the speed and accuracy of load regulation are greatly improved, and the main steam pressure and temperature fluctuate within a reasonable range. This optimization strategy can be used for reference for the same type of units.