Decompression combined air-gap membrane distillation method and device thereof

Abstract

The invention provides a decompression combination airgap membrane distillation method and a device thereof. The device comprises an airgap membrane distillation component, a decompression membrane distillation component, a first heat exchanger, a second heat exchanger, a first membrane distillation water producing collecting tank, a second membrane distillation water producing collecting tank, a circulating pump, a heat pump, a vacuum pump, a raw water tank and a connecting pipeline. The decompression combination airgap membrane distillation method comprises the following steps: feed liquid entering the airgap membrane distillation component is additionally heated through the heat pump; the heat pump produces cold water which is used for cooling producing water of the two membrane distillation units, namely the airgap membrane distillation component and the decompression membrane distillation component; after being cooled, the unevaporated feed liquid entering the decompression membrane distillation component flows in the raw water tank to converge with new raw water, then is sent to the airgap membrane distillation component through the circulating pump to absorb heat for temperature rise, enters the heat pump to continue to add heat, and finally enters the next cycle. The cooling effect of vacuum membrane distillation is utilized, so that the outlet temperature of decompression membrane distillation feed liquid is lowered. Heat transfer of cold and hot fluid is carried out by the heat pump, and therefore a high-flux airgap membrane distillation process is realized.

Description

technical field [0001] The invention relates to a membrane distillation process and a device thereof, in particular to a decompression combined air-gap membrane distillation method and a device thereof applied to water purification treatment, chemical industry separation of concentrated liquid and water desalination. Background technique [0002] Membrane distillation technology is a new type of liquid separation technology combined with membrane technology and traditional distillation technology. Compared with ordinary evaporators, one of the most notable features of membrane distillation is that the effective evaporation area per unit volume is large, so that the device can be used under normal pressure, It operates efficiently in the evaporation process at a lower temperature, and the equipment is made of plastic materials, which avoids the corrosion of metal materials under high salinity. Compared with reverse osmosis, membrane distillation is a heat-driven process with ...

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Problems solved by technology

Therefore, the membrane distillation process requires a large amount of additional cooling water to condense the steam of the membrane distillation. If the raw water is used as the cooling water, the water vapor generated during the membrane distillation process is directly exchanged with the raw water through a heat exchanger, such as air-gap membrane distillation. Then the raw water cannot fully absorb the latent heat of steam. In order to increase the water production ratio, the temperature difference between the membrane filament and the heat exchange tube must be reduced, which will result in low membrane distillation flux.

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