Furnace flue heat exhaust gas drying closed pulverizing coal-fired boiler unit with exhaust water recovery

Abstract

The invention provides a fume and hot exhaust dried closed pulverization coal-fired boiler unit with a function of exhaust water recovery. The fume and hot exhaust dried closed pulverization coal-fired boiler unit is characterized in that a weighing coal feeder controls coal feed for a boiler, an air-locking powder feeder is used for conveying pulverized coal and preventing the pulverized coal from channeling with air, an air exhaust preheater heats a part of ambient cold air into hot air, a part of the hot air, the other part of ambient cold air and a part of hot exhaust are mixed into primary air, the primary air and the pulverized coal are mixed in an air-powder mixer into air-powder mixture, the other part of the hot air is used as secondary air to be fed into a pulverized coal burner, an exhaust water recovery device cools high-humidity exhaust discharged by a pulverization subsystem so as to obtain a great deal of condensate and discharge cold exhaust, an air exhaust preheater is connected with the exhaust water recovery device and heats the cold exhaust into hot exhaust, and fume extracted from a fume suction opening and the other part of the hot exhaust are mixed into drier which is then fed into a raw coal pre-drying device.

Description

technical field [0001] The invention relates to a coal-fired coal-fired boiler unit of a coal-fired power station with exhaust gas and water recovery, and specifically relates to boiler air supply, pulverization, pulverized coal combustion and flue gas water recovery technologies. Background technique [0002] Lignite has the characteristics of high moisture, high volatile content, low calorific value, low ash melting point, low abrasiveness and easy spontaneous combustion. Lignite accounts for about 40% of the world's total coal reserves worldwide. my country's lignite accounts for about 16% of the total domestic coal reserves, mainly distributed in the eastern part of Inner Mongolia and the junction of the three northeastern provinces and Yunnan. The lignite in Inner Mongolia and Northeast China belongs to aged lignite, with a total moisture of 25-40%; the lignite in Yunnan belongs to young lignite, with a total moisture of 40-60%, and contains wood fiber. In addition, t...

AI Technical Summary

Problems solved by technology

However, compared with conventional bituminous coal boilers, the thermal efficiency of these lignite boilers is lower (about 2 percentage points lower) and the price is higher. This is mainly due to the large amount of flue gas in the lignite boiler, so the heat loss of the boiler exhaust is higher. , the boiler volume is also larger

In addition, the high-moisture coal-fired direct blowing pulverizing system needs to extract high-temperature furnace smoke as the main component of the desiccant of the pulverizing system, which makes the primary air contain a large amount of inert gases such as furnace smoke and water vapor, which makes the stable combustion of the boiler more difficult. difficulty

[0006] In conventional intermediate storage bunker-type pulverizing system boilers, in order to have a certain coal feeding buffer capacity and make the pulverizing process and the combustion process relatively independent, a pulverized coal bunker is often provided. However, for lignite and Zhundong coal with high volatility In terms of coal types, setting up a pulverized coal bunker in the pulverizing system to store flammable, explosive and highly volatile pulverized coal requires high requirements for the explosion-proof design of the pulverized coal bunker, which increases the difficulty of ensuring the safe operation of the pulverizing system

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