PLC-based low-nitrogen combustion control method and system

Abstract

The invention discloses a PLC-based low-nitrogen combustion control method and system. According to the boiler operating parameters fed back by the distributed control system DCS, the programmable controller PLC obtains the corresponding secondary damper opening command and the separate overburning air SOFA damper opening command in the pre-set low-nitrogen combustion control model, And the corresponding target value of nitrogen oxide emission; so that DCS can use the secondary damper opening command and SOFA damper opening command to control the corresponding secondary damper and SOFA damper; PLC according to the measured value of nitrogen oxide fed back by DCS and the current The NOx emission target value is used to determine the SOFA damper bias; the PLC superimposes the SOFA damper bias with the current SOFA damper opening instruction obtained from the low-nitrogen combustion control model to obtain the corrected SOFA damper opening instruction, So that the DCS uses the corrected SOFA damper opening command to control the SOFA damper. In this way, the low-nitrogen combustion control of the boiler can be effectively realized, and the economic and environmental protection optimization operation of the boiler can be realized.

Description

technical field [0001] The invention relates to the field of boiler optimization combustion control, in particular to a PLC-based low-nitrogen combustion control method and system. Background technique [0002] In 2012, the Ministry of Environmental Protection issued the new "Emission Standards of Air Pollutants for Thermal Power Plants", which clearly stipulates strict emission standards for nitrogen oxides (NOx) in coal-fired power plants. Domestic coal-fired power plants have successively carried out low-nitrogen combustion for boilers Reconstruction Project. After the low-nitrogen combustion transformation project is completed, in order to achieve the ideal low-nitrogen combustion effect, both the boiler efficiency and the nitrogen oxide emissions must be considered, which requires that the pulverized coal, secondary air and separate burn-off air ( SeparateOverFireAir, referred to as: SOFA) ratio relationship. [0003] At present, in coal-fired power plant boilers usin...

AI Technical Summary

Problems solved by technology

Under this control method, the load does not change, but when factors such as boiler coal quality, coal mill operation mode, and nitrogen oxide emissions change, the combustion characteristics of the boiler also change accordingly. The original secondary air and SOFA air The air distribution scheme is no longer applicable to the combustion characteristics at this time. Under this control method, the secondary air and SOFA air distribution schemes cannot be adjusted simultaneously with the boiler combustion characteristics, resulting in a mismatch between the air distribution scheme and the combustion characteristics requirements, and ultimately resulting in NOx emissions and boiler combustion efficiency are adversely affected

This control method is relatively extensive, and does not have the ability to optimally control low-nitrogen combustion when factors such as boiler coal quality, coal mill operation mode, and NOx emissions change.

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