Open pulverizing exhaust gas heating type boiler unit

Abstract

The invention provides an open powder processing waste steam heater type boiler unit. The unit is characterized in that a weighing coal feeder measures, regulates and controls the weight of raw coal corresponding to the boiler coal supply fed into a furnace, a steam locker is used for preventing air crossflow of coal powder and maintaining smooth circulation of coal powder, an air waste steam pre-heater is used for further heating part of warm air to obtain hot air, part of the hot air and the other part of warm air are mixed to serve as primary air, an air and powder mixer mixes the primary air with the coal powder to obtain an air and powder mixture, the other part of the hot air serves as secondary air to be directly fed into a coal powder burner, and a waste steam water recycling device brings in part of waste steam and recycles water in the waste steam; the air waste steam pre-heater is connected with the waste steam water recycling device to heat part of cold waste steam obtained after water recycling to form hot waste steam, and mixes the other part of the waste steam, part of smoke extracted from a smoke extraction port, and the hot waste steam to serve as drying agents which are fed into a raw coal pre-drying device.

Description

technical field [0001] The invention relates to an open pulverizing exhaust gas heating type boiler unit of a coal-fired power station, in particular to boiler air supply, cold air preheating, pulverizing, 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, the pred...

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 the existing lignite pulverization system, the desiccant of the pulverization system is made by mixing furnace smoke and hot air. On the one hand, this makes the desiccant have a high oxygen content, which is unfavorable for the safe operation of the pulverization system. On the other hand, it also makes the grinding The moisture content of the exhaust gas at the outlet of the coal machine is low, which is unfavorable for the economic recovery of moisture in the exhaust gas

[0007] 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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