High-moisture-content lignite predrying method and system integrated with thermal power plant

Abstract

The invention discloses a high-moisture-content lignite predrying method and system integrated with a thermal power plant. In the method, lignite is dried by using hot air as a fluidizing agent and a drying medium in a fluidized bed dryer; and a heater is built in the fluidized bed dryer to supply partial heat for drying. The lignite predrying system integrated with the thermal power plant comprises the fluidized bed dryer, the heater built in the dryer, a deduster, a gas-gas heat exchanger, a gas-water heat exchanger, an air heater and a fan. According to the system, waste heat in the system and low-grade heat energy in the power plant are fully utilized to dry the lignite. By applying the method and the system disclosed by the invention, the moisture content of the lignite fed into a furnace can be reduced, the heat loss of a boiler due to exhaust gas can be reduced, and the efficiency of the lignite boiler is increased; the low-grade heat energy and waste heat resources in the thermal power plant are fully utilized, so that the consumption of high-grade energy sources in a drying process is reduced, and the power generation efficiency of a lignite power plant is increased.

Description

technical field [0001] The invention belongs to the field of coal-fired thermal power generation systems, and relates to a method and system for pre-drying high-moisture lignite. Background technique [0002] At present, in most lignite power plants, lignite with a moisture content of 30% to 50% is not pre-dried, but is directly in contact with the high-temperature flue gas extracted from the furnace in the coal mill to achieve the purpose of drying, and the flue gas used for drying And the water vapor produced by drying is sent into the furnace together with the pulverized coal, resulting in a decrease in furnace temperature, poor combustion stability, increased flue gas volume, a corresponding increase in furnace cross-sectional area and volume, and increased boiler manufacturing and installation costs. At the same time, the exhaust heat loss increases, and the thermal efficiency of the boiler decreases, which in turn reduces the power generation efficiency of the power pl...

AI Technical Summary

Problems solved by technology

But on the one hand, the steam compression process needs to consume a considerable amount of high-grade mechanical work, which greatly reduces the efficiency of the power station; on the other hand, there are still many technical problems in the large-scale equipment and work reliability of the steam recompression technology. Therefore, the popularization and application of this technology is greatly limited.

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