RU2069085C1 - Method of manufacturing diaphragm roll member - Google Patents

Abstract

FIELD: film welding. SUBSTANCE: method comes to assembling two diaphragms with drain gauze in between into pack. Drain gauze plays the part of permeate outlet channel. Then diaphragm pack is welded over perimeter and connected hermetically to permeate outlet pipe with provision of communication between pipe inner space with permeate outlet channel. This done, diaphragm pack is wound around permeate outlet pipe with turbulizer placed between pipe coils. Weld seam is covered with polymer film over perimeter of diaphragm pack and additional weld seams are made over diaphragm pack in parallel with pack working sides, pitch being 100-450 mm. Diaphragm pack is impregnated with liquid, and vacuum not lower than 750 mm Hg is built in inner space of permeate outlet channel. Width of weld seams over perimeter is 5 - 10 mm, and that of auxiliary seams, 2-3 mm. Width of polymer film is 2-5 mm greater than width of weld seam over pack perimeter. EFFECT: enlarged operating capabilities. 3 cl, 3 dwg, 1 tbl

Description

 The invention relates to membrane technology, and in particular, to methods for the manufacture of spiral-wound coil membrane elements made using heat sealing, designed to separate liquid media by reverse osmosis and ultrafiltration methods.

 The most common method for manufacturing rolled membrane elements is a method in which the edges of the drainage sheet are impregnated with a special adhesive during winding of the bag onto a permeate outlet tube to tightly separate the pressure cavity and the permeate collection cavity.

 Existing technology provides for the operation of trimming the ends, i.e. when the package is wound, uneven edges are formed, which leads to a decrease in the filtering surface and a significant consumption of membrane material and glue.

 Currently, information has appeared that in the manufacture of a rolled membrane element using heat sealing.

 A known method of manufacturing a roll element, which consists in the fact that between the bearing surfaces of the membranes, a permeate discharge layer is laid, and the membranes themselves are welded around the perimeter. A stack of membranes is wound around the permeate outlet tube so that the permeate channel seals tightly with the layer of axial holes to provide a tight connection between the permeate outlet layer and the permeate outlet tube.

 However, during heat sealing along the perimeter of the package, there is a high probability of distortions and, as a result, creases and cracks in the weld. There are various ways to address these shortcomings.

 For example, there is a known method of manufacturing a spiral-wound membrane element [3] where a membrane package together with temporary mounting elements is wound in a spiral, the edges of the wound package are temporarily fastened. The bag is gradually unwound while the fastened edges are pulled through the welding fixture so as to weld the bag inside (temporary fastening is then removed).

 However, the known method has the following disadvantages: welding of the membrane package around the perimeter, primarily on the side of the working edges, is carried out in the process of winding the package on a permeate tube and is carried out with a certain step, with an overlap of the welds. At the same time, the package is in the winded state, which requires sophisticated special equipment.

 The objective of the invention is to increase labor productivity by reducing the complexity of manufacturing a membrane roll element by heat sealing while maintaining the quality of the weld.

 The problem is achieved due to the fact that in the known method, which includes assembling two membranes in a bag and a drainage mesh placed between them, which acts as a permeate outlet channel, heat sealing along the perimeter of the bag, hermetically connecting the bag to the permeate discharge tube to ensure that its inner surface communicates with the permeate discharge channel and subsequent spiral winding of the membrane package around the permeate tube with placement between the turns of the turbulator, according to the invention, around the perimeter of the weld along covered with a polymer film, along the entire package parallel to its working sides with an increment of 100 450 mm, auxiliary seams are made, the membrane package is impregnated with liquid and a vacuum below 750 mm Hg is created in the internal cavity of the permeate transfer channel.

 The width of the welds along the perimeter is 5 10 mm, and the auxiliary 2 3 mm, and the width of the polymer film by 2 5 mm exceeds the width of the weld.

 To increase the efficiency of the manufacturing process of the rolled membrane element, heat sealing is carried out along the perimeter of a flat package, and before winding the package onto the permeate pipe, auxiliary welds are made and a vacuum is created in the permeate pipe.

 A comparative analysis of the proposed solution with the known one shows that the proposed method is characterized in that along the perimeter of the package the weld is covered with a polymer film, along the entire package parallel to the working edges in increments of 100 450 mm, auxiliary joints are made, the membrane package is impregnated with liquid and created in the internal cavity of the permeate channel vacuum below 750 mmHg

 In the proposed method, heat sealing of the main and auxiliary seams is performed on a flat package with subsequent evacuation in order to remove air between the elements of the package. In this case, all the elements of the bag fit very tightly together, forming a "whole", and with the subsequent winding of the bag on a permeate tube, the formation of transverse folds does not occur. Moreover, the greater the vacuum, the denser the fit of the components of the package to each other. However, too much vacuum is impractical, because requires special equipment, the process time increases, therefore, productivity decreases.

 It was experimentally determined that the creation of a vacuum below 750 mm Hg is optimal.

 When winding roll packages of membranes of large width, even with preliminary evacuation, transverse folds can form. In this case, before winding along the entire package of membranes parallel to the working sides, auxiliary seams are made, the main purpose of which is to prevent the displacement of the elements of the package relative to each other during winding and to ensure the mechanical strength of the package.

 With an increase in the pitch of the auxiliary joints, the probability of the formation of transverse folds increases when the package is wound on a permeate tube due to the mechanical shift of the membrane elements during winding. With a decrease in the pitch of the auxiliary seams, the possibility of the formation of transverse folds during winding decreases, but the likelihood of the formation of through holes increases, which leads to a decrease in the quality of the package itself.

 It was experimentally determined that the optimal value of the pitch of the auxiliary joints is 100 450 mm.

 The width of the auxiliary weld is selected from the conditions for ensuring a snug fit of the elements of the package to each other and to prevent their displacement during subsequent winding. With an increase in the width of the auxiliary weld, the probability of displacement decreases, but the filter surface decreases, with a decrease in the width of the weld, the filter surface increases, but certain technological problems arise during welding, since with a decrease in the width of the weld the probability of electrode displacement relative to each other increases, which can lead to undigested package and can cause mechanical damage to the package (breakthrough, etc.).

 It was experimentally determined that the optimal value of the width of the auxiliary weld is 2 3 mm.

 During liquid separation processes using roll-on membrane elements, the fluid flow is supplied to the end face of the membrane filter element, i.e., the weld zone is constantly under the influence of a moving fluid flow, the speed of which can vary from 0.1 to 2 3 m / s.

 Under the influence of hydraulic shock, stratification of the weld can occur, membrane integrity in the transition zone from the weld to the filter surface (boundary zone) can be damaged, which leads to depressurization of the filter element and its premature failure.

 To ensure the mechanical strength of the filter element after welding around the perimeter of the packet, the weld zone is covered with a film, for example, by applying adhesive, and, in order to protect from damage to the boundary zone, the width of the polymer film exceeds the width of the weld. An increase in the width of the polymer film leads to a decrease in the filtering surface; a decrease in the width of the polymer film increases the likelihood of cracking in the boundary zone, which can lead to depressurization of the packet.

 It has been experimentally determined that the excess of the width of the film with respect to the width of the weld by 2 5 mm is optimal.

 The proposed technical solution will be clear from the following example and the accompanying drawings.

 In FIG. 1 shows a welded membrane pack with a drainage mesh.

 In FIG. 2 shows the process of winding a membrane pack onto a permeate tube.

 In FIG. 3 shows a roll membrane element assembly.

The following notation is used in the figures and in the text:
1 membrane;
2 membrane;
3 docking holes;
4 drainage mesh;
5 turbulizer;
6 weld along the perimeter of the membrane package;
7 auxiliary weld;
8 protective polymer film;
9 permeate tube.

The membrane filter element is assembled from two membranes 1 and 2 (material
ultrafiltration cellulose acetate membrane UAM-100 TU 6-05-221-339-79) and drainage mesh (fabric material knitted fabric, knitted base, for draining TU 17-09-168-85) in a bag (400 x 500 mm) thus that the drainage grid 3 is located between the bearing surfaces of the first and second membranes. In this case, one of the membranes has docking holes 3 for connection to the permeate tube 9.

 The folded package is welded around the perimeter using a welding unit containing pressure carriages with heating elements (10 x 530 mm), a pneumatic unit and a control unit with a time relay.

Welding mode: current strength 33 A, heating time 20 s, specific compression force 5 kg / cm ² , holding time 50 s.

 The width of the obtained weld along the perimeter of the filter element (6) is 10 mm.

 Auxiliary welds are performed on a welding machine with a heating element width of 3 mm. Since the width of the package is 400 mm, then perform one auxiliary shock 7.

 Welding mode: current strength 15A, heating time 10 s.

 Then, a protective polymer film 8 of epoxy adhesive is applied to the surface of the weld along the perimeter 6 in the ratio of resin: hardener as 5: 1 (Epoxy resin grade ED-20, GOST 10-587-84. Hardener grade UP-583 TU 6-05 -241-331-84).

 The width of the polymer film is 12 mm. Cure time 4 hours at room temperature.

 The welded bag is joined with the permeate pipe 9 by combining the docking holes 3 on the membrane 2 and the permeate pipe 9. The joint is sealed with epoxy adhesive in the ratio of resin: hardener as 5: 1 (epoxy resin grade GOST 10-587-84 ED-20 , hardener UP-583 TU 6-05-241-331-84). Cure time 4 hours at room temperature.

 The permeate tube 9 with a membrane package hermetically attached to it is mounted on a winding machine. The package is wetted with water and a vacuum of 750 mm Hg is created through the permeate tube 9 in the internal cavity of the permeate channel Vacuum leak time 120 s.

 Then a turbulent mesh 5 (material kapron fabric for sieves 8 ПЧ 300 ТУ 17-62-1038-82) is placed on the membrane package and the roll is wound (see Fig. 2). After winding the roll, its surface is wrapped with an adhesive tape LT-19 TU 6-17-626-79 and the vacuum is turned off (see table 1).

Claims (3)

 1. A method of manufacturing a rolled membrane element, comprising assembling two membranes in a bag and a drainage mesh placed between them, which acts as a permeate transfer channel, heat sealing along the perimeter of the package, tightly connecting the membrane package to the permeate transfer tube to ensure that its internal cavity communicates with the permeate transfer channel and the subsequent spiral winding the membrane package around the permeate tube with placement between the turns of the turbulator, characterized in that the weld around the perimeter is covered with poly measuring film, along the entire membrane package parallel to its working sides with increments of 100 to 450 mm, auxiliary welds are made, the membrane package is impregnated with liquid and a vacuum below 750 mm Hg is created in the internal cavity of the permeate transfer channel. Art.  2. The method according to claim 1, characterized in that the width of the welds along the perimeter is 5 10 mm, and the auxiliary welds 2 3 mm  3. The method according to claim 1, characterized in that the width of the polymer film is 2 5 mm greater than the width of the weld along the perimeter of the package.

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