Lignite drying method and lignite drying system

Abstract

The invention discloses a lignite drying method and a lignite drying system. The lignite drying method comprises the following steps that (1) lignite is placed into a raw material tower; (2) gas in the raw material tower is exhausted to a drying tower so that the pressure in the raw material tower can be reduced, wherein the drying tower carries out drying processing on the gas; (3) the gas processed through drying in the step (2) is fed into the raw material tower again; (4) the step (2) and the step (3) are repeated until dry lignite is obtained. According to the lignite drying method, due to the fact that the gas in the raw material tower is exhausted to the drying tower, the pressure in the raw material tower can be reduced, moisture in the lignite can rapidly evaporate at a low temperature, energy consumption can be reduced, the drying rate can be increased, and meanwhile, the accidents such as spontaneous combustion and explosion, caused by local high temperature, of the lignite are avoided; in addition, due to the fact that the whole lignite drying system runs at the low pressure, the amount of dust generated by air flow when the air flow passes through the raw material tower is reduced.

Description

Technical field [0001] The invention relates to the field of industrial technology, in particular to a lignite drying method and a lignite drying system. Background technique [0002] Lignite is a coal with a low degree of coalification, and its reserves account for more than 13% of my country's current coal reserves. Lignite is characterized by high water content, large porosity, high volatile content and low calorific value. my country's lignite generally contains about 20-50% of total water, while in some countries, such as Australia's lignite, the water content can reach more than 70%. A large amount of lignite with high moisture content is directly used for combustion, not only the boiler combustion is unstable, but also the efficiency is low. Because the process of water evaporation will take away a lot of heat energy, the combustion exhaust heat loss is large, and the thermal efficiency of power generation is low. In addition, the high moisture content makes lignite onl...

AI Technical Summary

Problems solved by technology

[0005] For the first technology, due to the high volatile content of lignite and the low ignition temperature, it is easy to cause overheating, which will deteriorate the coal quality and cause spontaneous combustion or explosion if the control is not good.

In order to prevent explosion, the method of lower hot air temperature has problems such as low drying strength and slow speed, and is not suitable for industrial production requirements.

[0006] For the second technology, although this technology has the characteristics of safety and high reliability, however, this technology still removes water through evaporation, so the energy consumption is high and the exhaust emission is large

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