Multistage continuous overheated steam drying system and method of low-rank coal

Abstract

The invention discloses a multistage continuous overheated steam drying system and method of low-rank coal. The multistage continuous overheated steam drying system comprises at least two stages of fluidized bed drying devices, wherein a discharging port of the first stage of fluidized bed drying device is connected with a feeding port of the second stage of fluidized bed drying device, and an air outlet at the top of the second stage of fluidized bed drying device is connected with an air inlet at the bottom of the first stage of the fluidized bed drying device; a feeding hole of the first stage of fluidized bed drying device is connected with a raw coal feeding device, an air outlet at the top of the first stage of fluidized bed drying device is connected with a dust removing device, an air outlet of the dust removing device is connected with a circulating fan, and an air outlet of the circulating fan is connected with a heating furnace; and a discharge port of the last stage of fluidized bed drying device is connected with a dry coal warehouse, and an air inlet at the bottom of the last stage of the fluidized bed drying device is connected with the heating furnace. Overheated steam and raw coal are dried by adopting a countercurrent operation, and partial purified steam can be recycled, therefore high heat utilization rate is achieved; and the multistage continuous overheated steam drying system and method disclosed by the invention have the advantages of simple whole drying process, continuous operation capability in an anaerobic environment, safety and reliability.

Description

technical field [0001] The invention relates to a technology for drying low-rank coal, in particular to a multi-stage continuous drying system and method for superheated steam of low-rank coal. Background technique [0002] Low-rank coal (such as lignite, long-flame coal, weakly caking coal and non-caking coal, etc.) usually has the characteristics of high moisture, high ash content, low calorific value, good chemical reactivity, flammability and fragility, so it is not suitable for long-distance transportation And long-term storage; but the direct combustion of unupgraded low-rank coal will cause serious environmental pollution, and the energy utilization rate of coal is low. Therefore, the drying and upgrading of low-rank coal is an important link to solve its efficient and clean utilization. [0003] In the prior art, the industrial application of low-rank coal drying has not been carried out on a large scale. The quasi-industrial-scale drying technologies mainly include...

AI Technical Summary

Problems solved by technology

Among them, the high-temperature flue gas tube drying technology has high power consumption and maintenance costs, and there are certain safety hazards in direct contact between pulverized coal and flue gas

Tubular dryers using low-pressure saturated steam or superheated steam as the drying medium have problems such as small drying capacity of a single device, small pipe diameter, easy blockage, high investment, and large pollution, which have not been widely promoted in the industrial field.

However, the internal heating steam fluidized bed drying technology also has problems such as serious wear of internal components, large exhaust gas emissions, unrecoverable waste heat, low thermal efficiency, low dehydration rate, and a lot of dust. The application in the field of industrial coal drying has also been greatly restricted.

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