Internal Heating Fluidized Bed Drying System Applicable to Lignite Air-cooled Generating Units

Abstract

The invention discloses an inner heating fluidized bed drying system applicable to a brown coal air cooling generator set and belongs to the field of power station energy conservation. In the brown coal air cooling generator set, a coal cabin is fixed above a weighting belt, and an inner heating fluidized bed dryingmachine with a built-in heat exchanger is additionally arranged between the weighting belt and a pulverizer. Hot air at an air cooling island outlet is used as a fluidizing and drying medium, part of exhaust steam of a turbine main body is used as a drying heat source. A dust remover is arranged at the air outlet of the drying machine, recovered dry pulverized coal and pulverized coal at the outlet of the drying machine are mixed and sent to the pulverizer for continued grinding; condensed water in a drying process enters into a backheating and heating unit. According to the invention, the turbine of an air cooling unit is used for discharging waste heat and hot air dried brown coal at the air cooling island outlet, so that energy intensity of the brown coal is increased, and the boiler efficiency is improved; cold source loss of the air cooling unit is reduced greatly, the energy recovering cost is low, and system economic benefits are good; temperature is maintained in a lower level during the drying process, and safety and reliability are good.

Description

technical field [0001] The invention belongs to the field of power station energy-saving equipment, and in particular relates to an internal heating fluidized bed drying system suitable for lignite air-cooled generating sets. Background technique [0002] my country's proven lignite resources amount to more than 130 billion tons, accounting for 13% of the country's coal reserves. Lignite is the youngest coal in raw coal, its volatile content is generally 40% to 50%, the total moisture can reach 20% to 50%, the air-dried base moisture is 10% to 20%, and the low calorific value is generally only 7 to 15MJ / kg. Due to the high moisture content of lignite itself, the amount of flue gas generated by combustion is relatively large, which makes the loss of boiler exhaust smoke larger than that of low-moisture coal. The direct combustion efficiency of boilers is low, the economy is limited, and the greenhouse gas emissions are also large. In addition, the high-moisture lignite has...

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Problems solved by technology

[0004] It should be noted that the main factories of lignite in my country are all located in the three north regions of China, and due to the unfavorable geographical conditions such as drought and little rain, the newly-built power stations in the above-mentioned areas mostly use air-cooling units, and the air-cooling units use ambient air as the cooling medium for steam turbine exhaust. Hot air (45°C-50°C), exhaust steam pressure 15kpa-35kpa, exhaust steam condensation temperature 50°C-65°C, and the current hot air at the outlet of the air-cooling island is generally directly discharged into the atmosphere, which not only causes a lot of cooling source loss, but also A certain degree of heat pollution to the environment

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