Flue gas hot air drying closed type pulverization coal-fired boiler unit with exhaust water recycling function

Abstract

The invention provides a flue gas hot air drying closed type pulverization coal-fired boiler unit with an exhaust water recycling function. The boiler unit used for combusting raw coal is characterized in that an air exhaust preheater heats environment cold air to obtain hot air, the first part of the hot air which serves as secondary air is directly fed into a pulverized coal burner, the second part of the hot air is directly fed into a drying agent mixing chamber to be mixed with flue gas pumped from a flue gas pumping opening, the mixture is used as drying agent and fed into a raw coal pre-drying device, the drying agent mixing chamber is respectively connected with the flue gas pumping opening and the air exhaust preheater, an exhaust water recycling device cools exhaust, high in humidity, discharged by a pulverization sub-system to obtain a large amount of condensate and discharges cold exhaust, one part of the cold exhaust is heated by the air exhaust preheater to form hot exhaust, the hot exhaust is mixed with the other part of the cold exhaust to form primary air, and the primary air enters an air-pulverized coal mixer to be mixed with pulverized coal to obtain air-pulverized coal mixture.

Description

technical field [0001] The invention relates to a closed pulverizing coal-fired boiler unit with fume and hot air drying for 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 addition, the predic...

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

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