LT4471B - Device for electrodialysis - Google Patents

Abstract

The electrical dialyser is designed for electrochemical treatment of liquid electrolytes, i.e. for salt removal and concentration. The electrical dialyser consists of electrodes, tightening disks (1, 2) with an installed in-between package made of interchanging anion (3) and cation (4) metabolic membranes and gasket frames (5), that are put in the middle of these membranes (3, 4), thus limiting salt removal and concentration chambers (6) to neighbouring membranes (3, 4). The gasket frames (5) have behind membranes (3, 4) protruding edge parts (7) with holes (8), which after the electrical dialyser is put together make liquid feeding and removal collectors. Every second aforementioned hole (8) is connected by channels (9) to a relevant salt removal or concentration chamber (6). The gasket frame (5) parts (10) with channels (9) are thicker than adjacent relevant gasket frame (5) parts (11) without channels - these are thinner than the rest of the gasket frame.

Description

The invention relates to the field of electrochemical treatment of liquids - electrolytes and can be used for the construction of filter press type electrodialysis machines with labyrinth frames or frames.

There is a known electrodialyzer (see SU1681433 A1, B01D61 / 42 ONLY, dated 30.03.1989) having electrodes, clamping plates, interposed with a package consisting of alternately anionic and cationic exchange membranes and frame spacers disposed between those membranes and limiting salt removal and concentration chambers between adjacent membranes. Frames - Gaskets have portions protruding beyond the membrane edges, with openings that, when the electrodialysis device is assembled, form collectors for supplying and removing fluids. Every other aforementioned hole is connected by ducts to an appropriate desalination or concentration chamber. The thickness of the frames and spacers of this electrodialyzer is the same throughout their area.

The disadvantage of the known electrodialysis device is the relatively high energy loss. To reduce them, the distances between the membranes, i.e. reduce the thickness of the frames - spacers. However, in frames 0.6-0.8 mm thick, the gaskets 20 would be difficult to make channels connecting the manifolds forming the manifolds to the desalting chambers. In addition, these channels could only be of very small cross-section and would thus result in an inadequate distribution of fluid flows in the multi-chamber apparatus, resulting in a reduction in the reliability of the apparatus.

The object of the present invention is to improve the reliability of the electrodialysis machine and to simplify its manufacturing technology.

The object of the achievement is that, in a known electrodialysis device having electrodes, the clamping plates are provided with a package consisting of alternately arranged anionic and cationic exchange membranes and frames - spacers disposed between those membranes and limiting salt removal and concentration chambers between adjacent membranes frames - spacers having protruding portions of membrane edges with apertures which, when the electrodialysis device is assembled, form collectors for supplying and removing fluids, wherein each of said apertures is connected by ducts to a respective desalination or concentration chamber, and frame-spacer portions with said ducts are made to a greater thickness, and adjacent corresponding portions, which have no channels, are just as thick as the rest of the frame-gasket. This makes it possible to increase the cross-sectional area of the ducts connecting the manifolds to the desalination chambers, thereby increasing the reliability of the electrodialysis machine and simplifying its manufacturing technology.

The invention is explained by the drawings, wherein FIG. 1 is a schematic side view of an electrodialyzer, FIG. 2 - FIG. 1, section A-A, figs. 3 - FIG. 2 Section B-B.

The proposed electrodialyzer has clamping plates 1 and 2 and electrodes (not shown). Between the plates 1 and 2 is a pack consisting of alternately anionic membrane 3 and cationic membrane 4 and frames-spacers 5 disposed between these membranes 3 and 4 (Fig. 1). Frame spacers 5 restrict respective desalination or concentration chambers 6 (Fig. 2) between adjacent membranes 3 and 4. Frame spacers 5 have protruding portions 7 of membrane edges 7 with apertures 8 which, when the electrodialysis unit is assembled, form collectors for fluid delivery and for removal.

Every second hole 8 of the same frame 8 is connected to the respective desalination or concentration chamber 6 by the channels 9 and 9 respectively. The frame gasket 5 parts 10 with the said channels 9 (fig. 3) are of a larger thickness and , having no channels, just as thick as the rest of the frame-spacer 5. The packet of membranes 3 and 4 and frame-spacer 5 are assembled such that each frame-spacer 5 is sandwiched between the membranes of anionic exchange 3 and cationic circulation 4. Each successive frame spacer 5 is rotated 180 ° about its longitudinal axis with respect to the frame spacer 5 preceding it, and it will already be between the membranes of the cationic circulation 4 and the anionic circulation 3. Thus, the thickened portions 10 of the frames-spacers 5 with the channels 9 and the thickened portions 11 without the channels are arranged alternately, so that the package thickness remains the same.

The membranes of the anionic metabolism 3 and the cationic metabolism 4 are alternately arranged. Between the two adjacent membranes 3 and 4, a corresponding desalting or concentration chamber 6 (alternately) is formed, bounded at the edges by a frame-spacer 5.

The electrodialysis works as follows.

The fluid (electrolyte) to be treated, such as desalinated water for desalting, is fed through a manifold consisting of holes 8 when the electrodialysis package is clamped by clamping plates 1, 2. The fluid under pressure 9 passes into the respective desalting or concentration chamber 6 and at the working membrane surface. The treated liquid is then removed through another manifold.

The proposed electrodialyzer completely avoids leakage between the desalting and concentration chambers due to the fact that due to the alternating thicknesses of the spacers 5 and 10 at the openings 8, the ends of the membranes are compressed very well and the respective chambers are sealed apart.

In addition, the proposed design allows to reduce energy loss and increase the reliability of the apparatus by reducing the membrane distances, resulting in the possibility of reducing the thickness of the frames-spacers.

The following table shows the technical characteristics of the proposed electrodialyzer compared to the prototype:

Technical characteristic Prototype Suggested Technical solution Membranes dimensions, mm 740x480 1500x480 Average Frame - gasket thickness, mm 1.6 0.8 Frame-spacers number in apparatus, pcs 600 800 Electricity consumption, kWh for 1 m ³ desalinated water 1.2 0.7

DEFINITION OF INVENTION

Claims (4)

DEFINITION OF INVENTION Electrodialysis device having electrodes, clamping plates (1,2), interposed with a pack consisting of alternately anionic (3) and 5 cationic (4) diaphragms and frames - spacers (5) disposed between said membranes (3) and (4) and restricting salt removal and concentration chambers (6) between adjacent membranes (3) and (4), frames - spacers (5) have protruding portions (7) of the membranes (3), (4) with holes (8) which, when the electrodialysis device is 10, forming collectors for supplying and removing fluids, and each of said second orifices (8) is connected by channels (9) to a respective desalting or concentration chamber (6), characterized in that the frame (5) said channels (9) being of greater thickness and adjacent frames 15-spacers (5) portions (11) having no channels - less than the rest of the frame-spacer (5).