Economizer hot water recirculation system applicable for subcritical steam drum boiler generator set, and working method thereof

Abstract

The invention relates to an economizer hot water recirculation system applicable for a subcritical steam drum boiler generator set, and a working method thereof. The hot water recirculation system comprises an economizer, a steam drum, a drop pipe and a water supply pipe, and a water outlet of the economizer, the steam drum and the drop pipe communicate with each other in sequence; the water supply pipe communicates with an inlet of the economizer; the hot water recirculation system further comprises a No.1 electric regulating valve, a No.2 electric regulating valve, a manual shutoff valve, aNo.1 check valve, a No.2 check valve, a circulating pump, a recirculation pipe and a bypass; the recirculation pipe communicates with a lower collection box of the drop pipe, and further communicateswith an inlet collection box of the economizer at the time; the recirculation pipe is provided with the circulating pump of which the both sides are provided with the No.1 electric regulating valve and the manual shutoff valve; the circulating pump is provided with the bypass which is provided with the No.2 electric regulating valve; and the recirculation pipe is provided with the No.1 check valve, and the water supply pipe is provided with the No.2 check valve. The hot water recirculation system can be used for preventing the economizer from being dry-burnt in the start-stop process, and improving the outlet smoke temperature of the economizer under the low load condition, so that the wide load denitrification is achieved.

Description

technical field [0001] The invention relates to an economizer hot water recirculation system suitable for a subcritical drum boiler generator set and a working method thereof, belonging to the field of power generation boilers, in particular to a subcritical drum boiler with wide-load denitrification requirements. Background technique [0002] During the start-up and shutdown phases of power plant boilers, due to the small amount of evaporation, there is no need to supply water to the steam drum, and the working medium in the economizer basically does not flow, and it is prone to dry burning, which will cause the working medium in the economizer to boil, and even cause water hammer. result in damage to the equipment. The traditional boiler design will set up a recirculation pipeline between the lower header of the downcomer and the inlet of the economizer. When the boiler starts and stops, the recirculation pipe is opened, and the working medium in the boiler is driven by th...

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Problems solved by technology

The traditional recirculation pipeline has a simple structure and is shut off after the boiler is in normal operation, such as the Chinese patent application number 201510052561.0, mainly because after the feedwater pump is put into operation, the pressure at the inlet side of the economizer is greater than the pressure at the lower header of the downcomer , it is easy to cause low-temperature feedwater to flow back to the header of the downcomer

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