Solution phase inversion membrane preparation solvent replacement and digestion device

Abstract

The invention relates to a solution phase inversion membrane preparation solvent replacement and digestion device and solves problems of present devices, such as high recovery cost, large solvent residual quantity in the membrane, low recovery rate of the solvent and difficulty in realizing solvent replacement and digestion continuous production. The technical scheme is as follows: the device provided by the invention contains a plurality of coagulation baths which are sequentially arranged from front to back; the first coagulation bath is provided with an outlet; the last coagulation bath is provided with an inlet; and adjacent coagulation baths communicate with each other through pipelines or openings on bath walls. The device provided by the invention has advantages of simple structure, high recovery rate of the solvent, low recovery cost and no sewage discharge, and can be used to realize continuous operation of the system.

Description

technical field [0001] The invention relates to a device used in the film-making process in water treatment, in particular to a solution phase inversion method film-making solvent replacement stripping device. Background technique [0002] The phase inversion method is to prepare a homogeneous polymer solution of a certain composition, and through a certain physical method to make the solution perform mass transfer and exchange of solvent and non-solvent in the surrounding environment, change the thermodynamic state of the solution, and make it change from homogeneous polymerization The solution undergoes phase separation, transforms into a three-dimensional macromolecular network gel structure, and finally solidifies to form a film. According to the different physical methods of changing the thermodynamic state of the solution, the phase inversion membrane method can be divided into the following types: solvent evaporation phase inversion method, heat induced phase inversio...

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Problems solved by technology

[0003] The above-mentioned solvent displacement dissolution process has the following problems: (1) The cost of solvent recovery is high: since the coagulation baths are not connected to each other, and the direction of the film in the coagulation bath is from front to back, the solvent contained in the solution in different coagulation baths The concentration is different. The solution contains the highest concentration of solvent in the first coagulation bath that contacts the membrane at the front, and the concentration is lower as it goes further back.

Considering the cost and efficiency of solvent recovery, usually only the solvent in the effluent of the first 1 to 2 coagulation baths is recovered, and the solution with low solvent content discharged from other coagulation baths is discharged as wastewater and enters the sewage treatment system. On the one hand, it leads to waste of water resources, and the solvent in the water will also bring environmental impact; on the other hand, it is necessary to build a sewage treatment system, which increases the investment and operating costs of membrane production, and the loss of some solvents will also lead to a further increase in operating costs

(2) The residual amount of solvent in the film is large, and the solvent recovery rate is low: as the production continues, due to the gradual increase of the solvent concentration in the solution in each coagulation bath, the driving force for the dissolution of the solvent from the film in the same coagulation bath gradually increases. Decrease, the amount of residual solvent in the film gradually increases, and reaches the maximum when the coagulation bath solution needs to be replaced, resulting in an unstable dissolution rate of the solvent from the film, and a large amount of residual solvent in the film

(3) The continuous production of solvent replacement and dissolution cannot be realized: when the concentration of the solution in the coagulation bath reaches a predetermined value, it must be discharged regularly (or recovered or discharged as waste water) and re-injected for production. During the replacement of the solution, the membrane production facility must be stopped. transport, affecting the continuity of production

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