Temperature Control Method of Indirect Flue Gas Heat Exchanger for 600mw Coal-fired Boiler

Abstract

The embodiment of the invention discloses a temperature control method for a 600MW coal-fired boiler indirect gas-gas heater. According to the temperature control method, control over the chimney exhaust gas temperature is a final control objective of the indirect gas-gas heater, the final control objective can be realized through reasonable control of the inlet water temperature of a first-class heat exchanger, the inlet water temperature of a second-class heat exchanger and the outlet gas temperature of the first-class heat exchanger, and adjustment can be made specifically through a steam heater regulating valve, a first-class heat exchanger by-pass regulating valve and a heat medium water-circulating pump frequency converter. The embodiment of the invention further discloses a temperature control device for the 600MW coal-fired boiler indirect gas-gas heater.

Description

technical field [0001] The invention relates to the field of indirect flue gas heat exchangers for 600MW coal-fired boilers, in particular to a temperature control method for indirect flue gas heat exchangers for 600MW coal-fired boilers. Background technique [0002] With the serious smog problem in northern my country, the country pays more and more attention to environmental protection. For coal-fired boilers in power stations, the concept of ultra-low emissions is proposed, that is, the pollutant emissions from boiler chimneys must be controlled within: NOx≤ 50mg / m 3 , SO 2 ≤35mg / m 3 , dust≤10mg / m 3 . In December 2015, the State Council issued a work plan for the comprehensive implementation of ultra-low emission and energy-saving transformation of coal-fired power plants, requiring coal-fired power plants across the country to complete ultra-low emission transformation by 2020. Among them, power plants in the central and eastern regions are required to complete befor...

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Problems solved by technology

[0003] Although the indirect flue gas heat exchanger is widely used in ultra-low emission projects of power plant boilers, its parameter control is a difficult point in its operation control due to the influence of the flue gas temperature characteristics of different load sections of the boiler.

In the low-load stage after the boiler is ignited, since the exhaust gas temperature of the boiler itself is low, and the exhaust gas temperature of the chimney needs to be controlled at a higher temperature (not lower than 80°C), this requires the control of an indirect flue gas heat exchanger In addition, in the stage of boiler load increase, as the exhaust gas temperature increases, the heat medium water temperature of the indirect flue gas heat exchanger also increases. There is a critical point between them, and the parameter control strategy before and after the critical point It is also different, how to accurately distinguish the critical point is also a difficult point of control; in addition, in the low-to-medium load stage, the coordinated control of the steam volume of the auxiliary steam heater and the flow rate of the heat medium water entering the primary heat exchanger is also an indirect flue gas Difficulties in heat exchanger control

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