Process method and system for recovering water from lignite drying flue gas

Abstract

The invention relates to a process and a system for recovering water from lignite drying flue gas. With the process and the system, problems such as complicated water recovery process, large land occupation, high fixed asset investment, and high operation cost are solved. A technical scheme provided by the invention comprises the steps that: water-containing high-temperature flue gas enters from a lower section of a washing tower, and is subjected to direct reflux contact and washing heat exchange with process water in the washing tower; vapor in the flue gas is partially condensed and enters dust-containing grey water; washed flue gas is discharged from a flue gas outlet at the top of the washing tower; dust-containing and oil-containing grey water after washing is delivered into a cooler from a grey water outlet at the bottom, and is further cooled to 45-50 DEG C; the grey water is delivered into an oil-water separator, such that waste oil is separated and discharged; the dust-containing grey water is delivered into a clarifier, such that upper-layer grey water and lower-layer slurry are obtained by separation; the upper-layer grey water is subjected to clarification and overflowing, and is delivered into a grey water tank, wherein a suspended solid concentration of the clarified upper-layer grey water is lower than 100ppm; and the upper-layer grey water is filtered, such that clean water with a dust content lower than 5ppm is obtained. The method and the system provided by the invention have the advantages of small investment, low land occupation, compact equipment, high operation rate, and low operation cost.

Description

technical field [0001] The invention relates to a process method and a system for recovering water from lignite drying flue gas. Background technique [0002] my country is rich in lignite resources, with proven reserves of 130.3 billion tons, accounting for about 13% of the country's coal reserves, mainly distributed in the northeast, northwest, southwest, and north China, concentrated in Inner Mongolia, Yunnan, and Heilongjiang provinces. my country's lignite resources are mainly processed and utilized by upgrading methods. [0003] The moisture content of lignite in northern my country is generally 30% to 50%. During the lignite upgrading process, about 90% of the moisture in lignite can be squeezed out, and a large amount of moisture will be taken out with the lignite drying flue gas. Generally, these drying The flue gas is directly vented, which not only causes pollution to the atmospheric environment, but also causes a large amount of water loss. For lignite producing...

AI Technical Summary

Problems solved by technology

The first two methods are biological treatment of reused water, this biological method covers a large area, high investment in fixed assets and high operating costs

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