Open pulverizing exhaust gas heating type boiler unit

Abstract

The invention provides an exhaust warm air type boiler unit for open coal pulverization. The boiler unit is used for burning raw coal and is characterized in that an exhaust air preheater is used for further heating a part of warm air to obtain hot air, a part of the hot air and the other part of the warm air are mixed to be used as primary air, an air-pulverized-coal mixer mixes the primary air and pulverized coal to obtain air-pulverized-coal mixture, the other part of the hot air is used as secondary air to be directly sent into a pulverized coal burner, an exhaust air water recovery device is used for leading a part of exhaust air in and recovering water in the exhaust air, the exhaust air preheater is connected with the exhaust air water recovery device to heat the part of cold exhaust air after water recovery to obtain hot exhaust air, a drying agent mixing chamber is connected with a smoke extracting opening and a gas outlet of the pulverized coal collector respectively, and the other part of the exhaust air, a part of smoke extracted from the smoke extracting opening and the hot exhaust air are mixed and then used as a drying agent to be sent 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

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