RU2290256C1 - Membrane filtering element of the roll type - Google Patents

Abstract

FIELD: designs of the membrane filtering elements of the roll type.

SUBSTANCE: the invention is pertaining to the designs of the membrane filtering elements of the roll type used for separation of the liquid mediums in the processes of the reverse osmosis, nano-, ultra- and micro- filtration. The technical result of the invention is the increased productivity and provision of realization of the filtration of both in the flowing and in the dead-end modes. The membrane filtering elements (MFE) includes the filtrate-withdrawing tube with radial holes along its length, around which there are helically reeled one or several membrane packets consisting of the folded with active side inside of the semi-permeable membrane with the inserted in it turbulizing net the interleaved sheets of the porous material. The butts of the elements are completely sealed by the method of potting with the thermoreactive glue composition or with the melt of the thermoplastic material, and its pressure-channels are open from the external cylindrical surface of the element. On the external cylindrical surface of the membrane filtering element there is the resilient shell fixed on the butt one side end on the disk, having the channels for entering of the subjected to filtration medium under the resilient shell. On the butt disk there is the seal collar of the double-side action, preventing the streamlining of the membrane filtering element by the filtered medium both from the right to the left and from the left to the right.

EFFECT: the invention ensures the increased productivity and provision of realization of the filtration of both in the flowing and in the dead-end modes.

3 cl, 4 dwg, 1 tbl

Description

FIELD OF TECHNOLOGY

The invention relates to the field of construction (device) of a roll-type membrane filter element (hereinafter ME).

ME consists of membrane bags alternating with sheets of drainage material for permeate removal, wound on a perforated perforated filter tube and sealed in a certain way.

MEs are widely used in almost all areas of industry in the processes of reverse osmosis, nano-, ultra-, microfiltration. The most widely used MEs are used for desalination of natural and waste waters of industrial enterprises, for the treatment of technological water for various industries, for the production of drinking water, including for domestic use.

The appearance of new ME structures is an inevitable consequence, first of all, of the creation of new membranes and an increase in the requirements for ME.

BACKGROUND

Various ME designs are known. MEs differ from each other in general design, manufacturing technology, applied structural materials, and sealing (Japan Patents No. 54-151571, 54-149384, 54-149383, 53-124179; US Patents No. 3966616, 3417870, 4235723, 4906372, 5538642 ; Copyright certificates No. 1205359, 1213100, 1595553).

Closest to the claimed design ME is shown in US patent No. 4906372. According to this patent, the ME contains a tube with holes for draining the filtrate, on which the sheets of the folded membrane are wound, inside each sheet there is a grid sheet, the sheets of the folded membrane are separated by a porous material. After winding, an ME is formed, which is a cylinder with an axial filtrate outlet pipe, inside which channels of the source water and filtrate are formed. Channels for water supply are open on both sides (ends) of the ME and from its outer cylindrical surface. The initial liquid is fed into one end of the ME and discharged through the other end. The filtrate is discharged through a filtrate outlet pipe.

The disadvantage of ME according to US patent No. 4906372 is the large sealing zone of the membrane bags, which reduces the working surface of the ME and its performance, as well as the inability to use ME for filtration in dead-end mode with regular regenerative countercurrent flushing and purging with compressed air.

SUMMARY OF THE INVENTION

The aim of the invention is to create a design ME with increased performance, which would provide optimal conditions for filtering both in flow and deadlock mode with regular regenerative countercurrent flushing and purging with compressed air.

According to the invention, the ME consists of a filtrate outlet tube 1 with radial holes along the length around which one or more membrane packets are spirally wound, each of which consists of a doubled semi-permeable membrane 7 with the active side inward with a sheet of turbulent mesh 8 and an intermediate porous material 9, the pressure channels of the element are open from its outer cylindrical surface (figure 1).

To reduce the sealing zone of the membrane packages and to increase the productivity of the ME due to this, its ends are completely sealed by pouring a thermoset adhesive composition or by melting a thermoplastic material 11.

According to the invention, in order to create optimal filtration conditions both in flowing and deadlock conditions with regular recovery countercurrent flushing and blowing with compressed air, an elastic, easily radially stretched shell 6 is mounted on the outer cylindrical surface of the ME, fixed from one end to the disk 3, having channels 4 for the entry of the filtered medium both into the end part of the element and under the elastic membrane, which occupies 70-80% of the ME length. A double-acting sealing cuff 5 is installed on the end disk, which prevents the filter medium from flowing through the ME both from left to right and from left to right. The ratio of the length of the membrane package to its width is from 1: 1 to 1: 3.

According to the invention, to improve drainage of the filtrate, the porous material may include at least two sheets of drainage material. The porous material may include one or more nets of a thickness of 0.2 to 2 mm.

The inventors found that the construction of the ME in accordance with the above features allows to increase its performance and use it for filtration in a dead end mode with regular regenerative countercurrent flushing and purging with compressed air.

The sealing of the ends of the MEs by pouring a thermoset adhesive composition or by melt of a thermoplastic material allowed to reduce the sealing area by 80-100% and thereby increase productivity by an average of 10%. The optimal conditions for filtering both in the flow-through and in the dead-end modes, which are traditional for membrane elements with regular recovery countercurrent flushing and blowing with compressed air, are achieved by the fact that an elastic, easily stretched in the radial direction shell is fixed on its outer cylindrical surface, fixed from one end to a disk having channels for the entry of the filtered medium both into the end part of the element and under the elastic shell and occupying 70-80% of the ME length. An increase in the length of the elastic shell to values exceeding 80% of the length of the ME leads to an increase in its resistance. Elastic sheath lengths of less than 70% of the ME length can lead to the formation of stagnant zones in the pressure channels of the ME and reduce its efficiency. At the same time, a double-acting sealing cuff is installed on the end disk, which prevents the filter medium from flowing around the ME both from right to left and from left to right.

In the operating mode of dead-end filtration (ultra-, microfiltration), the filtered medium enters the ME channels and under the elastic membrane. The elastic shell 6 is stretched in the radial direction and forms the collector of the original filtered medium, from where it has access to all parts of the membrane (figure 2). When conducting countercurrent re-flushing (Fig. 3), water or a water-air mixture for flushing is supplied from the side of the opposite end of the ME, while the elastic shell 6 is pressed against the outer cylindrical surface of the ME, providing high linear flow rates of water in the pressure channels necessary for effective washing. During washing, water is also supplied to the filtrate outlet pipe from the drainage channel.

When using the inventive ME in the flow filtration mode (reverse osmosis, nanofiltration), the initial filtered medium is supplied to the ME from the end face opposite to the end face with a disk 3 on which a double-acting sealing sleeve 5 is installed (Fig. 4). In this case, the elastic shell 6 is pressed against the outer cylindrical surface of the ME, thereby ensuring high linear flow rates of water in the channels, necessary for the efficient implementation of the reverse osmosis or nanofiltration process.

As the turbulizer mesh 8, it is preferable to use knotless mesh from 0.3 to 2 mm thick. The best drainage material is a knitted warp knit fabric made from Dacron yarn, impregnated with a solution of epoxy resin and its subsequent curing.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a sketch of the inventive ME with showing its main details and their location relative to each other.

Figure 2 shows a sketch of the inventive ME indicating the direction of flows of the original filtered medium and the filtrate in the operating mode of dead-end filtration.

Figure 3 shows a sketch of the inventive ME indicating the direction of flow of the original filtered medium and the filtrate in the recovery countercurrent washing of dead-end filtration.

Figure 4 shows a sketch of the proposed ME indicating the direction of flow of the original filtered medium, concentrate and filtrate in the operating mode of flow filtration:

1 - leachate tube;

2 - holes in the tube to drain the filtrate;

3 - disk;

4 - holes in the disk for receipt of the original filtered medium;

5 - a sealing cuff of bilateral action;

6 - elastic shell;

7 - membrane;

8 - sheet turbulence mesh;

9 - porous material;

10 - the place of the sealed connection of the porous material with adjacent membranes (connection membrane - porous material-membrane) in the area of the outer cylindrical surface of the ME;

11 - place of the sealed connection of the ends of the ME (membrane-porous material-membrane-turbulent mesh connection).

DETAILED DESCRIPTION OF THE INVENTION

The applicant, together with the inventors, made and tested prototype MEs with an external diameter of 65 and 100 mm and a length of 1016 mm.

The main design features, starting materials and test results of the prototype ME are shown in the table.

The main parameters and test results of prototype ME.

Table Name of the main parameters and operational characteristics Prototype Data one. 2. 3. four. 5. 6. 7. 1. Used membrane web: 1.1. nanofiltration composite membrane + + - - - + - 1.2. Microfiltration membrane (pore size 1.00 μm) - - + + + - + 2. The outer diameter of the sample ME, mm 2.1. 65.0 + + + + - - + 2.2. 100.0 - - - - + + - 3. The ratio of length to width of the membrane package 3.1. 1: 1 + - + - + - - 3.2. 1: 3 - + - + - + + 4. The number of membrane packets in ME four 10 four 10 four 10 10 4.1. The composition of the porous material 4.1.1. 1 sheet of drainage material + + - - - + - 4.1.2. 2 sheets of drainage material and 1 mesh 0.2 mm thick - - + - + - + 4.1.3. 2 sheets of drainage material and 1 mesh 2 mm thick + 5. The length of the elastic sheath - 70% of the length of the element - + - - - - + - 80% of the length of the element - - - + + + - 6. Sealing of membrane bags in ME: 6.1. according to US patent 4906372 + - + - - - - 6.2. according to the present invention - + - + + + +

7. Operational characteristics of ME 7.1. Productivity (per filtrate), l / h 180 205 280 * 320 * 725 * 410 335 * 7.2. Selectivity,%: - according to MgSO ₄ 96.9 97.0 - - - 95.9 - - by turbidity (GOST 3351-74) - - 74 73.5 76.1 - 74 ÷ 76 Test conditions: Pressure, MPa 1,6 1,6 0.15 0.15 0.15 1,6 0.15 Temperature ° C twenty twenty twenty twenty twenty twenty twenty * - initial performance values

Control tests were carried out:

- nanofiltration elements on a 0.2% solution of MgSO ₄ ,

- microfiltration elements on tap water (Klyazma water intake in Vladimir).

Analysis of the test results of experimental samples of elements allows us to draw the following conclusions:

1. Both methods of sealing membrane bags in the elements are quite reliable:

the selectivity of the element (see clause 7.2 of the table) practically corresponds to the selectivity of the membrane used.

2. When sealing by the method of pouring ends in comparison with sealing according to the prototype, an increase in the effective (working) area of the membrane in the element is ensured, and, as a result, an increase in its productivity under other identical conditions (see clause 7.1., Samples of elements 1 and 2; 3 and 4). This effect is observed in the entire range of the ratio of the length to the width of the membrane package from 1: 1 to 1: 3 and in the range of the thickness of the mesh used in the drainage channel, from 0.2 to 2 mm, and also in the range of the length of the elastic membrane 70-80% of the length item.

3. Resource tests of microfiltration elements manufactured according to the present invention, 4, 5, 7 for 100 hours in a dead-end mode in tap water with cyclic recovery reverse-flow leaching, showed them, of course, a positive effect on the life of the element: after each washing, the performance of the element restored to the level of 80-85% of the original. In this case, the adhesive joints experienced multiple alternating loads (compression-tension) without violating the tightness of the ME. The design of the microfiltration element made according to US patent No. 4906372, does not allow cyclic recovery backward washing. Therefore, the performance of the element manufactured according to US patent No. 4906372, after operation during the first hours, drops to 5-10% of the initial productivity.

4. The ME according to the present invention has an increased productivity compared to the prototype and provides optimal conditions for filtering both in flowing and deadlock conditions with regular regenerative countercurrent flushing and blowing with compressed air in the entire range of the ratio of the length to width of the membrane package from 1: 1 to 1: 3 and in the range of thickness of the mesh used in the drainage channel, from 0.2 to 2 mm, as well as in the range of the length of the elastic shell 70-80% of the length of the element.

Claims (3)

1. A roll-type membrane filter element (ME), including a filtration tube with radial holes, around which one or more membrane bags are spirally wound, each consists of a semi-permeable membrane with the active side folded in and a turbulent mesh embedded in it and intermediate sheets of porous material , the pressure channels of the element are open from its outer cylindrical surface, characterized in that the ends of the elements are completely sealed by pouring a thermoset composition or melt of a thermoplastic material, while on its outer cylindrical surface there is an elastic, easily radially stretchable shell, occupying 70-80% of the length of the element, fixed from one end to a disk having channels for the passage of the filtered medium under the elastic shell, and a double-acting sealing cuff is installed on the end disk, which prevents the flow of ME filtered medium both from right to left, and from left to right, the ratio of the length of the membrane package its width is from 1: 1 to 1: 3. 2. The membrane element according to claim 1, characterized in that the porous material includes at least two sheets of drainage material. 3. The membrane element according to claim 1 or 2, characterized in that the porous material includes at least one mesh with a thickness of 0.2 to 2 mm.

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