Gas-disturbance type membrane distilling method and membrane distilling device

Abstract

The invention discloses a gas-disturbance type membrane distilling method and a membrane distilling device. The method comprises the following steps of: enabling air to pass through a hydrophobic membrane from one side of a heat-side solution chamber of the membrane distilling device to enter into a heat-side solution chamber, and performing disturbance on a to-be-processed solution in the heat-side solution chamber; allowing the air introduced into the heat-side solution chamber and steam of a purified product to pass through the hydrophobic membrane from the heat-side solution chamber and enter a cold-side purifying chamber positioned on the other side of the heat-side solution chamber; and finally collecting the purified product. The membrane distilling device at least comprises three independent areas, namely a compressed air chamber (1), the heat-side solution chamber (2) and the cold-side purifying chamber (3), wherein the compressed air chamber (1) and the cold-side purifying chamber (3) are respectively positioned on the two sides of the heat-side solution chamber (2); and each area is separated from each other by using the hydrophobic membrane (4). By using the method, the temperature and concentration polarization are effectively reduced, membrane pollution is reduced, and membrane distillation flux is improved; and the membrane distilling device has the characteristics of low cost, simplicity in operation and easiness for maintenance.

Description

technical field [0001] The invention relates to the technical fields of extraction of volatile solute or gas dissolved in solution, treatment of saline waste water, desalination of sea water, preparation of ultrapure water, etc., specifically a method for reducing temperature polarization and concentration polarization 1. A method and a membrane distillation device for air-disturbed membrane distillation that reduce membrane fouling and increase membrane distillation flux. Background technique [0002] Membrane distillation technology originated in the United States in the 1960s, and it did not develop rapidly until the 1980s. It is a new type of membrane separation technology. It is widely used to extract volatile solutes or gases dissolved in solutions due to its advantages of working under normal temperature and pressure, simple equipment and easy to master, and utilization of waste heat. Salt wastewater treatment, seawater desalination, ultrapure water preparation and ...

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Problems solved by technology

[0004] ① In the process of membrane distillation, the distillation flux of the membrane is very low, and no membrane with high distillation flux has been developed so far; among the four forms of membrane distillation, the distillation flux of vacuum membrane distillation is the largest, but it is still not enough. satisfactory

[0005] ② Due to the existence of temperature polarization and concentration polarization, the operating state of the system is unstable, resulting in a rapid decline in the distillation flux of the membrane; especially in vacuum membrane distillation, because its distillation flux is compared with the other three forms is larger, so the temperature polarization and concentration polarization are more serious, and the distillation flux of the membrane is also most affected by temperature polarization and concentration polarization

[0006] ③ Membrane pollution is also very prominent in the process of membrane distillation. With the prolongation of use time, on the one hand, due to the effect of concentration polarization, the local concentration on the surface of the membrane will increase, which will usually promote the saturation of some solute components in the solution. Under certain conditions, it will even crystallize and deposit, or become a colloidal substance attached to the membrane surface, blocking the membrane pores and forming membrane pollution; on the other hand, when the salt crystal particles adhere to the membrane surface, it can cause the membrane to wet, Even leakage seriously affects the service life of the membrane

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