Reheat steam temperature control method of four-corner tangential boiler under low-nitrogen combustion mode

Abstract

The invention discloses a reheat steam temperature control method of a four-corner tangential boiler under a low-nitrogen combustion mode. The method comprises the following steps: the advanced heat support is provided for variable load of a set through dynamic advanced feedforward in a main control loop of the boiler; a ratio of upper-layer powder feeders to lower-layer powder feeders is reasonably controlled; and an air volume ratio of a main combustion area to a burnout area is reasonably controlled. The method effectively solves the technical problems of easy movement of the flame center position of a hearth, difficulty of stable control of reheat steam temperature and in particular, increment of desuperheater water of a reheater due to the overheat phenomenon of the boiler caused by high fluctuation of the reheat steam temperature under the working condition of variable load.

Description

technical field [0001] The invention relates to the field of thermal process control in thermal power plants, in particular to a method for controlling the reheating steam temperature of a boiler. Background technique [0002] The current national environmental protection policy is becoming increasingly stringent. The "Emission Standards of Air Pollutants for Thermal Power Plants" GB13223-2011 puts forward clear limit requirements for the NOx emission concentration of thermal power units. The new emission reduction subsidy policy further encourages power plants to carry out the reduction of NOx emissions from boilers. Relevant technological transformation. Boiler low-nitrogen combustion technology is an effective means to reduce NOx generation from the source, and can greatly reduce the operating cost of tail flue gas denitrification. In recent years, most thermal power units in China have completed boiler low-nitrogen burner transformation. [0003] However, under the low...

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Problems solved by technology

[0003] However, under the low-nitrogen combustion mode, the combustion characteristics of the boiler change, especially for the four-corner tangential combustion mode boiler, the combustion in the furnace is divided into two heat load centers, the main combustion zone and the burnout zone, and the center of the furnace flame is easy to move. The reheat steam temperature is difficult to control stably, especially under variable load conditions, the reheat steam temperature fluctuates greatly, prone to boiler overheating, and the amount of desuperheating water in the reheater increases, which seriously affects the safety and economy of boiler operation

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