Boiler primary air heating device provided with flue gas tubular heat exchanger

Abstract

The invention discloses a boiler primary air heating device provided with a flue gas tubular heat exchanger. The boiler comprises a furnace hearth, a flue, a primary air fan, a boiler economizer, a horizontal low temperature overheater, a chimney, an induced draft fan, a denitration device, an air preheater and a coal mill, wherein the primary air heating device comprises a high temperature furnace smoke tube, the tubular heat exchanger, a cooling furnace smoke branch pipe and a hot furnace smoke fan; one end of the high temperature furnace smoke tube is a smoke extracting opening; the smoke extracting opening is formed in the furnace hearth; the other end of the high temperature furnace smoke tube is connected with the flue gas heating inlet of the tubular heat exchanger; the cooling furnace smoke branch pipe communicating with the chimney and the induced draft fan is further mounted on the high temperature furnace smoke tube; the flue gas outlet of the tubular heat exchanger is connected with the flue between the denitration device and the boiler economizer and the flue between the boiler economizer and the horizontal low temperature overheater through the hot furnace smoke fan and a pipeline; the air outlet of the air preheater is connected with the air inlet of the coal mill through the tubular heat exchanger; and the air from the air preheater enters the coal mill after being heated by the tubular heat exchanger.

Description

technical field [0001] The invention belongs to the technical field of coal-fired power generation, and relates to a pulverizing system and a combustion system of a coal-fired power plant boiler, in particular to a medium-speed pulverizer direct-blowing system for drying and grinding lignite with high moisture content, high volatile content, and low calorific value. Primary air heating with flue gas tube heat exchanger for boilers in powder systems. Background technique [0002] Lignite is a coal with a short formation time in coal resources and the mineral coal with the lowest degree of coalification. It is the initial product of peat deposition and dehydration and compaction into organic biorock. It is named for its brown or dark brown appearance. Lignite is mainly used as fuel in power plants, but also in fields such as the chemical industry. Lignite has high volatile content (dry ash-free base volatile content Vdaf > 37%), high moisture content (over 30% total moistu...

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Problems solved by technology

[0007] The purpose of the invention of this application is to solve the problem that the primary air temperature supplied to the coal mill is lower than the design value, resulting in poor drying capacity and insufficient system output in the pulverizing system, and to provide a boiler with flue gas tube type The primary air heating device of the heat exchanger, the invention extracts the hot furnace smoke in the furnace and heats the primary air, which can effectively overcome the above shortcomings

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