System adopting high concentration CO2 flue gas as coal dust drying medium in boiler

Abstract

The invention relates to a system adopting a high concentration CO2 flue gas as a coal dust drying medium in a boiler and belongs to the technical field of energy technology application and CO2 capture. The flue gas which is dehydrated and heated to a certain temperature and contains over 95 percent of CO2 is used as the drying medium for coal dust pulverizing. The drying medium is an inert gas with low oxygen content so as to solve the problem of easy explosion of a coal pulverizing system when hot air is used as the drying medium and improve the operational safety of the coal pulverizing system. Meanwhile, compared with the temperature of the hot air, the initial temperature of the drying medium can be greatly improved so as to reduce the power consumption of a coal mill, improve the fineness of coal dust, improve combustion efficiency, reduce the exhaust gas temperature and improve the heat efficiency of the boiler.

Description

technical field [0001] The invention belongs to energy technology application and CO 2 In the field of capture technology, it specifically relates to a CO 2 A system in which flue gas with a content of more than 95% is used as a drying medium for pulverized coal. Background technique [0002] Traditional pulverized coal combustion power plant boilers generally use hot air as the medium for drying and grinding raw coal into pulverized coal. After being preheated by the air preheater, part of the cold air passing through the blower enters the pulverizing system to dry and carry coal powder, and the other part is directly sent into the furnace as secondary air to ensure complete combustion of coal powder. Since the oxygen content of the hot air is 21%, the dried pulverized coal-air mixture has the risk of explosion, and the outlet temperature of the coal mill must be controlled below the explosion limit temperature, so that the temperature of the hot air fed into the coal mil...

AI Technical Summary

Problems solved by technology

Since the oxygen content of the hot air is 21%, the dried pulverized coal-air mixture has the risk of explosion, and the outlet temperature of the coal mill must be controlled below the explosion limit temperature, so that the temperature of the hot air fed into the coal mill is limited, generally Therefore, on the one hand, the drying efficiency of the coal mill is affected; on the other hand, when the moisture content of the raw coal changes, in order to adapt to the limitation of the outlet temperature of the coal mill, some cold air must be mixed in, which displaces the air preheater The hot air flow rate reduces the heat recovery of flue gas at the tail of the boiler and reduces the thermal efficiency of the boiler

Images