System and method for comprehensive utilization of waste heat and pressure of coal-fired boilers

Abstract

The invention discloses a comprehensive utilization system and method for waste heat and pressure of a coal-fired boiler. The system includes a sewage expansion vessel, a heat exchanger, an expander, a condenser and a working medium pump; , the sewage expander has two water outlets, wherein the first outlet of the sewage expander is connected to the second expander, and the second expander is connected to the condenser hot well of the coal-fired unit; the second outlet of the sewage expander is connected to the first heat exchanger The inlet is connected, the outlet of the first heat exchanger is connected to the inlet of the third heat exchanger; the inlet of the second heat exchanger is connected to the flue gas pipe of the boiler flue; the working medium outlet of the first heat exchanger is connected to the first expander, After the outlet of the first expander is connected to the condenser, the working medium pump is connected to the working medium inlet of the third heat exchanger. The system can comprehensively utilize the residual heat and residual pressure of the boiler's continuous sewage discharge, and generate electricity, so as to improve the system performance of the subcritical coal-fired power station.

Description

technical field [0001] The invention relates to the technical field of power generation by utilizing waste heat of working medium, in particular to a comprehensive utilization system and method for waste heat and pressure of a coal-fired boiler. Background technique [0002] In subcritical coal-fired power plants, the boiler feed water, although chemically treated, still contains some salt. During the operation of the power station, the salt in the steam drum will gradually increase. In order to ensure the safe operation of the boiler and steam turbine, some high-salt water will be discharged from the steam drum to control the quality of the water in the steam drum, which is called boiler blowdown. Boiler blowdown is generally divided into continuous blowdown and regular blowdown. Continuous sewage discharge refers to the continuous discharge of sewage from the steam drum during the operation of the boiler. Power stations generally use continuous expansion vessels to recove...

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Problems solved by technology

However, this part of the boiler exhaust gas is directly discharged into the atmosphere after dust removal, desulfurization and denitrification treatment, resulting in a large amount of energy loss.

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