Desulfurization wastewater evaporation and concentration zero discharge system and process based on double circulation loops

Abstract

The invention discloses a desulfurization wastewater evaporation and concentration zero discharge system and process based on double circulation loops. The system comprises a tower body, wherein the tower body is sequentially provided with a thick slurry circulation pool, a hot flue gas inlet, a thick slurry spraying layer, a partition plate and a thin slurry spraying layer from bottom to top; a plurality of gas rising caps are arranged on the partition plate; the thick slurry circulating pool is connected with the thick slurry spraying layer through a circulating pump; the hot flue gas inlet is connected with a hot flue gas source and is provided with a quenching spraying device, and the quenching spraying device is connected with a waste water thin slurry system. By adopting the arrangement mode, blockage caused by precipitation of calcium sulfate crystals can be effectively prevented, so that safe and stable operation of the demister and even the whole evaporation and concentration system is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of desulfurization wastewater treatment, and in particular relates to a zero-discharge system and process for desulfurization wastewater evaporation and concentration based on double circulation loops. Background technique [0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] At present, the process of using the waste heat of low-temperature hot flue gas (>150°C) to concentrate, reduce and zero-discharge desulfurization wastewater is as follows: in the desulfurization wastewater spray concentration tower, the hot flue gas is directly introduced from the bottom, and the spraying The desulfurization wastewater below is directly in contact with heat exchange and mass transfer to realize evaporation and concentration of desulfurization wastewater. A demister is installed on the top of the spray concentration ...

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Problems solved by technology

[0004] The inventor found in the research that the desulfurization wastewater treatment method has the following problems: a) The desulfurization wastewater contains supersaturated calcium ion Ca2+ion and sulfate ion SO42+, once it is rapidly heated by hot flue gas, it will cause a large amount of calcium sulfate crystals in the desulfurization wastewater to precipitate, and in the circulating spray pipe, nozzle 1. Adhesive deposits occur on the circulating pump, which makes the flow section rapidly decrease, and then blocks the channel, making it impossible to maintain long-term normal operation; b) After spraying the hot flue gas introduced into the concentration tower, it may also cause atomized spraying of wastewater in the tower The rapid drying of the particles, attached to the surface of the internal parts of the spray concentration tower, causes the blockage of crystal particles inside the spray concentration tower, and may cause accidents such as the collapse of the demister in severe cases; c) the precipitation of calcium sulfate crystals in the desulfurization wastewater is Endothermic reaction, therefore, a large amount of precipitation of calcium sulfate will absorb a large amount of heat in low-temperature flue gas, which reduces the utilization rate of waste heat of low-temperature hot flue gas

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