Furnace smoke drying closed pulverization coal-fired boiler unit with exhaust water recovery

Abstract

The invention provides a fume-dried closed pulverization coal-fired boiler unit with a function of exhaust water recovery. The fume-dried closed pulverization coal-fired boiler unit is characterized in that a weighing coal feeder weighs coal fed into a boiler and performs adjustment control, an air-locking powder feeder is provided, a drier mixing chamber is connected with a fume suction opening and a gas outlet of a pulverized coal collector and allows a first part extracted from exhaust and a part of fume extracted from the fume suction opening to be mixed into drier which is fed to a raw coal pre-drying device, 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 heats a part of ambient cold air into hot air and heats the cold exhaust into hot exhaust, a part of the hot air, the other part of the ambient cold air and the hot exhaust are mixed into primary air, an air-powder mixer mixes the primary air and pulverized coal into air-powder mixture, and the other part of the hot air is used as secondary air directly supplied to a pulverized coal burner.

Description

technical field [0001] The invention relates to a smoke-drying closed-type pulverizing coal-fired boiler unit with exhaust gas water recovery in a coal-fired power station, in particular 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 ...

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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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