Lignite drying water recycling and drying tail gas recycling system

Abstract

The invention relates to a lignite drying water recycling and drying tail gas recycling system which comprises a hot blast heater, a drier, a dry type deduster, a heat pump machine set, a mixing chamber and a water spraying chamber, wherein the mixing chamber is used for mixing fume of the hot blast heater and a recycled tail gas heated by the heat pump machine set into low-temperature hot fume to be used as a drying medium of the drier; the dried tail gas and the cold water sprayed out from a nozzle of the water spraying chamber are sufficiently mixed and subjected to heat-humidity exchange in the water spraying chamber; part of steam in the dried tail gas is condensed into water to be recycled; at the same time, visible heat and latent heat of vaporization are released; the cold water used in the water spraying chamber is supplied by the heat pump machine set; the water recycled in the water spraying chamber flows out through an overflowing tube and is collected. The fume discharged from the water spraying chamber is heated by an air cooling condenser of the heat pump machine set, is subsequently fed into the mixing chamber, is mixed with the fume generated from the hot blast furnace, and is subsequently used as the drying medium of the drier. The system is at a low temperature and is dry, and the oxygen content of the drying medium is low, so that volatiles in coal are prevented from being lost, and precious water resource is recycled.

Description

technical field [0001] The invention relates to lignite drying and upgrading equipment, in particular to a lignite drying water recovery and drying tail gas recycling system. Background technique [0002] Lignite has huge reserves in my country and the world. Because the water content is more than 30%, it directly participates in combustion. The evaporation process of water will take away a lot of heat energy, resulting in a large heat loss in combustion exhaust, low power generation efficiency, and a large amount of greenhouse gas emissions. Therefore, high The use of moisture lignite presents special challenges. High-moisture lignite is directly used for combustion, which not only causes unstable combustion of the boiler, but also has low efficiency. High moisture makes these coals only available locally, and it is impossible to transport them over long distances, which greatly limits the scale of coal mining. [0003] The dry upgrading of lignite rich in water is to unde...

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Problems solved by technology

Among them, the energy-saving and environment-friendly drying method and device for coal slime and lignite (publication number CN101881191A) is the prior art closest to the present invention. This method uses a heating furnace as a heat source, uses a drum dryer to dry lignite, and utilizes a heat pump unit Recovering the waste heat and moisture in the drying tail gas improves the drying efficiency of the drum dryer. However, in this patent, high-temperature flue gas is used for direct drying, which inevitably produces volatiles such as CO, and the system safety is poor. At the same time, the system uses surface Type indirect heat exchanger recovers the moisture and heat energy in the dry tail gas, the heat and mass exchange efficiency is low, the heat exchanger equipment is huge, the investment is high, and the water recovery efficiency is low

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