A system and method for improving low-load operation performance of coal-fired boilers

Abstract

The invention discloses a system and a method for improving the low-load performance of a coal-fired boiler. The method of the present invention includes: according to the coal humidity detected by the coal humidity sensor, adjusting the net flue gas extraction, so that the coal humidity is lower than the target coal humidity; according to the furnace flame temperature, main steam temperature, reheat steam temperature, The relative deviation of flue gas temperature at the SCR inlet controls the first cooling air flow or the second cooling air flow; the system of the present invention includes: a slag cooling system of a slag dryer, a coal-fired drying system and a control system. According to the boiler furnace flame temperature, main steam temperature, reheat steam temperature, SCR inlet flue gas temperature and coal humidity, the invention adjusts the net flue gas extraction volume, the first cooling air flow rate, and the second cooling air flow rate, which can effectively improve the efficiency of coal combustion. When the boiler is under low load, the furnace flame temperature, SCR inlet flue gas temperature, and boiler efficiency can be reduced, and the humidity of the incoming coal can be reduced, thereby effectively improving the low-load performance and operating economy of the coal-fired boiler.

Description

technical field [0001] The invention belongs to the technical field of power plant boilers, in particular to a system and method for improving the low-load operation performance of coal-fired boilers. Background technique [0002] Due to the strong randomness and intermittency of hydropower, wind power, photovoltaic and other renewable energy power generation, the large-scale grid connection of its power generation increases the peak-valley difference of the power grid system, which brings obvious negative effects to the safe and stable operation of the power system. influences. In order to improve the level of renewable energy consumption, improving the deep low-load operation capability of coal-fired thermal power units has become an essential work content. [0003] The air-cooled dry slag discharge system has the advantages of low water consumption, high utilization rate of bottom slag, and small impact on the environment. It has been widely used at home and abroad in re...

AI Technical Summary

Problems solved by technology

[0003] The air-cooled dry slag discharge system has the advantages of low water consumption, high utilization rate of bottom slag, and small impact on the environment. It has been widely used at home and abroad in recent years. When the coal-fired power unit operates at low load, it may bring adverse effects such as a decrease in the overall temperature of the furnace. At the same time, the combined results of the two aspects are not conducive to the stable combustion of pulverized coal due to the external moisture carried by the coal itself.

In addition, when coal-fired units operate at low load, there may be problems that the main steam temperature, reheat steam temperature, and SCR inlet flue gas temperature deviate greatly from the design value. These factors restrict the low-load operation performance of coal-fired units.

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