RU2262978C2 - Diaphragm ultra-microfiltration roll material and method of restoration of its serviceability - Google Patents

Abstract

FIELD: filtration.

SUBSTANCE: proposed diaphragm ultra-microfiltration roll material consist of perforated tube to let out filtrate, diaphragm packs spirally wound on tube through turbulizing net and sealing cup arranged on one end face of roll element. Diaphragm packs contain drain plate and semipenetrable diaphragm. Drain plate consists of two sheets, one place onto the other, forming common drain channels. From outside, roll element is provided with free outlet of turbulizers separating diaphragm packs and is wrapped in turbulizing net. Sealing cup of definite diameter is arranged at end face of roll material opposite to delivery of liquid to be filtered. Method of restoration of serviceability of diaphragm ultra-microfiltration element includes washing by filtrate delivered in counterflow through let-out line of filtrate and treatment with water-air mixture delivered in line of flow of filtered medium. Method is effected at definite parameters of flow rate of washing liquid and mixture and time of washing and treatment.

EFFECT: possibility of restoration of serviceability of filtering element in service, improved service characteristics.

3 cl, 1 tbl, 1 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to the design of a membrane ultramicro-filtration roll element operating by the method of "dead end filtration" ("Dead End Filtration" provides for the separation of the filtered fluid into two parts - sediment and filtrate. "Flow filtration" provides for the separation into three parts - sediment, concentrate and filtrate. ), and to a method for restoring its performance during operation. Such a roll element (hereinafter for brevity - MFRE), as well as membrane roll elements of known constructions operating according to the “flow filtration” method, consists of a filtrate-discharge perforated tube spirally wound thereon through a turbulent mesh of membrane bags containing a drainage sheet and a semi-permeable a membrane, and a sealing sleeve located at one of the ends of the roll element. Semi-permeable ultramicro-filtration membranes used in MFRE have through holes - pores whose size (average diameter) is from 0.005 to 5.0 μm, respectively, smaller than the average particle size of the substance that is separated (filtered) on the MFRE from the filtered liquid and which are in it in the form of dispersions, emulsions, colloidal or true solutions.

According to our data, MFRE, which would implement the “dead end filtration method” (this method is used in cartridges or cartridge filters), is not known in the literature and industry.

Known designs of roll and cartridge membrane filtration elements equipped with ultra- or microfiltration membranes are widely used to obtain drinking water from contaminated sources, to purify various liquids from suspended solids, colloids and bacteria, in particular for the treatment of saline water before desalination using reverse osmosis.

During the operation of the MFRE, due to the contamination of its film membrane with substances released from it from the filtered liquid, it lowers its initial working capacity (productivity decreases and the working pressure rises) to the point where it becomes necessary to clean the MFRE, which is usually carried out by washing with chemical reagents. Finding an effective way to restore the operability of a membrane ultramicro-filtration roll element operating by the "dead-end filtration" method (today, in general, there are no ways to restore the operability of membrane filtration elements operating in this mode), and the corresponding MFRE design is an urgent task, to ensure the competitiveness of MFRE compared with the cartridge roll element, i.e. provide higher performance, increased service life, compactness, low cost, simplicity and reliability in operation.

BACKGROUND

Known designs of membrane filtration roll elements operating according to the "flow filtration" method differ both in the general layout and in separate units and elements (parts), semi-permeable membranes, membrane bags, turbulators and drains, gaskets, sealing cuffs, as well as restoration technology operability during the period of operation (Japanese patents No. 53-124179, 54-151571, 54-149384, 54-149383; US patents No. 3966616, 3417870, 4235723.5598642; USSR copyright certificates No. 1205359, 1213100, 1595553; "Technical described ie and instruction manual for filter elements of nanofiltration type ERN-KP ", Vladimir, 1999, CJSC Scientific and Technical Center" Vladipor ";" Technical description and instruction manual for filter elements of ultrafiltration type ERU-P ", Vladimir, 2000, Scientific and Technical Center "Vladipor" CJSC; Technical Bulletin "Contaminants of reverse osmosis membranes and their removal", 1999, TSB 10706, Hydranautics).

Membrane ultrafiltration roll elements operating according to the "dead end filtration" method are unknown to us.

Closest to the claimed design of MFRE and the method for restoring the health of the roll element is described in the "Technical description for elements of the type ERU-P". According to this description, the ERU-P consists of a filtrate-discharge perforated tube spirally wound on it through a turbulizer grid (turbulizer) of membrane packets containing a drainage sheet and a semipermeable membrane, and a sealing cuff located at one of the ends of the roll element.

The method of restoring the efficiency of the ERU-P, which works according to the "flow filtration" method, consists in washing it with a stream of filtrate, softened or demineralized water at a pressure of 0.5-1.0 kg / cm ² , complementing this washing by treating the element with solutions of chemical compounds ( the so-called "chemical washing") such as phosphates, citric acid, surfactants, sodium hypochlorite.

The disadvantages of the known design (element type ERU-P) are:

- the use of the method of "flow filtration", which does not allow you to clean the filtered fluid completely, and therefore, a limited scope;

- the use of a relatively expensive and insufficiently effective method of restoring performance during operation, requiring the use of special chemicals.

SUMMARY OF THE INVENTION

The objective of the invention is to create a design MFRE, which would implement a "dead-end filtration method" in relation to the roll element and due to this would be characterized by increased performance compared to the membrane cartridge filter element. But at the same time, it would allow to restore the efficiency of the filtration element during its operation. In this regard, the objective of the invention is also the development of a method of washing MFRE during its operation.

According to the invention, the tasks are solved in that in the known design of the membrane filter element, which consists of

- filtrate-discharge perforated tube;

- spirally wound on this tube through a turbulent grid of membrane bags containing a drainage web and a semipermeable membrane, and

- a sealing cuff located on one of the ends of the roll element;

fundamental changes are introduced, which consist in the fact that

- the drainage web is made of two sheets superimposed on each other, the grooves of which are located inside the double layer and form common drainage channels;

- outside, the roll element has a free exit of turbulators separating the membrane packets, and is wrapped with a turbulizer grid;

- the sealing cuff is located on the opposite end of the roll element relative to the supply of the filtered fluid and has an outer diameter selected from the ratio

D _m = D + (5 ÷ 10 mm),

where D is the outer diameter of the roll element, mm; D = d + 2δ;

d is the average outer diameter of the roll element after winding the membrane bags, mm;

δ is the thickness of the layer of the outer turbulence grid, mm.

In order to increase the performance of MFRE and the effectiveness of the claimed restoration of its performance during operation, the membrane packages of the claimed MFRE are performed in a shape close to square. This makes it possible to equalize the velocity of the filtered fluid and flushing media over the entire area of the membrane bags, eliminate stagnant zones, and increase the reliability of the structure throughout the entire period of operation.

According to the invention, a method of restoring the health of the claimed MFRE is that the washing of the roll element is carried out in two stages:

- at the first stage, the roll element is washed with the filtrate, feeding it countercurrently through the output line of the working filtrate with a flow rate of 0.5 to 10.0 m ³ / h for 2 to 10 seconds;

- at the second stage, the roll element is treated with a water-air mixture in a ratio of 5 to 30 volume parts of air per 1 volume part of water, feeding this mixture along the line of movement of the filtered medium with a flow rate of 1.0 to 15 m ³ / h for 2 to 10 sec

The inventors found that the design of the roll membrane ultramicro-filtration element in accordance with the above features made it possible to create a roll element that implements the "dead end filtration method", and at the same time capable of multiple restoration of its performance during operation. A membrane filter element has been created that has not only all the positive properties of the membrane cartridge element, but also superior to these properties. And what is especially remarkable is the creation of an element capable of regeneration, which is absent in the cartridge microfilter.

To implement the invention in an industrial environment, all available materials can be used if they meet the above-mentioned features of MPE and the method of washing it.

So, for the manufacture of membrane bags, it is possible to use ultra- and microfiltration membranes on a woven and non-woven base substrate made of various polymers, including polyamides, polysulfone, cellulose esters, polyethersulfones, polyarylates, fluoroplast. The limitation here is the condition of the mechanical strength of the membranes: so that a membrane package can be formed from them - 180 ° bending and the ability to glue or weld.

Almost all rigid polymers are suitable for the manufacture of a filtrate-discharge tube - polyvinyl chloride, polyethylene, polypropylene, aminoplast, polycarbonate, including filled ones, as well as inorganic materials such as ceramics and metals.

As a turbulizer separating the membrane packets and an external turbulizer, which wraps the roll element on the outside, mesh-free meshless materials with a thickness of 0.6 to 2.0 mm and having a mesh size of 2 × 2 to 6 × 6 mm can be used.

A drainage web, which is used according to the invention in the form of sheets superimposed on one another, can be made, as a preferred option, from a warp knitted polyethylene terephthalate material, impregnated with a curable epoxy resin based on the weight gain of the web when impregnated from 12 to 30% by weight. But you can use any other permeable embossed material. It is important here that the drainage web has grooves from 0.05 to 1.5 mm on one side that extend along the entire web, and a single (in the size of the grooves) batch of this material is used to form a two-layer drainage web whose grooves would form general drainage channels as provided by the invention.

The sealing collar is usually made of thermoplastic polyurethane with a size that is provided according to the invention. The thickness of the cuff is determined by the design data of the MFRE and must withstand the working pressure of the filtered fluid and the flushing system. Typically, the working pressure is in the range from 0.3 to 4.0 kg / cm ² , the flushing pressure is from 0.1 to 3.0 kg / cm ² .

LIST OF DRAWINGS FIGURES

Figure 1 shows the basic design of the inventive MFRE (in longitudinal section), placed in the housing of the membrane module in which the MFRE is operated.

Figure 1-a shows a double layer of the membrane web, which is used according to the invention, and the location of its grooves for the formation of common drainage channels.

1 - a filtrate-discharge perforated tube, which has through holes in its wall (11) in the area of their contact with the drainage sheet (5) of the membrane bags (2).

2 - membrane bags with which this fluid is filtered and which consist of a drainage sheet (5) wrapped (packed) with a semipermeable membrane (4) during the manufacturing (winding and gluing) of MFRE.

3 - a turbulizer grid (turbulizer), which separates the membrane packets (2) and serves as a channel for supplying the filtered medium to the outer surfaces of the membrane packets (2).

4 - semipermeable ultrafiltration or microfiltration membrane.

5 - drainage web (according to the invention - double), which is located inside the membrane bags (2) and which is connected to the filtrate-discharge tube (1).

6 is an external turbulizer grid, which, according to the invention, is wrapped with MFRE (instead of the previously used impermeable film according to the known construction) and which, according to the invention, is spatially connected to turbulators (3) separating the membrane packets (2) and forming channels for supplying a filtered fluid to the membrane bags (2).

7 - a sealing cuff that closes the free exit of the filtered liquid and the washing liquid passing through the external free channel (12) above the external turbulence grid (6) to the drain line (10) of the washing filtrate and the air-water mixture.

8 - the cover of the membrane module housing (13), in which the MFRE is operated and flushed and which is connected to the drain line (10) of the flushing liquids.

9 - shut-off valve on the branch line (10). Closed - during the filtration period, open - during the washing (restoration of operability) MFRE.

10 - line for the removal of washing filtrate and water-air mixture.

11 - through holes in the filtrate-discharge tube, used to drain the filtrate and supply the washing filtrate.

12 - free zone (annular channel) for the passage of the filtered liquid and the flushing water-air mixture to the surface of the external turbulator (6) and then, radially, along the turbulators of the membrane packets to the surface of the semipermeable membrane.

13 - the membrane module housing in which the MFRE is operated and flushed.

14 - common drainage channels formed by a double layer of drainage fabric (5).

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

In accordance with the invention, the authors made and tested 9 different MFRE samples, the indicators of which are shown in the table (items 1, 1.1-1.5).

The tests were carried out on tap water (filtered liquid).

The performance of the tested MFRE samples was measured by the amount of filtrate (calculated per unit time) discharged through the filtrate-outlet pipe (1) with a fully closed tap (9). Filtered fluid, as will be done under real industrial conditions, was supplied from the pressure end face of the MFRE, as shown in Fig. 1 (arrow), using a standard membrane module housing with an internal diameter of D _m = 65 mm, 100 mm and 200 mm respectively.

The washing (restoration of performance) of the contaminated MPE, the pollution level of which is given in paragraph 1.6 of the table, was carried out in two stages, as provided by the invention.

In the first step, the filtrate wash liquid was supplied through the filtrate-discharge tube (1), i.e. countercurrently through the filtrate withdrawal line. The end of the first washing step was controlled by a time relay.

At the second stage, MFRE was treated with a water-air mixture, feeding it along the line of motion of the filtered medium, i.e. from the pressure end face of the MFRE, as shown in Fig. 1 (arrow). In this case, the MFRE flushing at two stages was carried out with the tap fully open (9).

After a 2-stage washing, the restored MFRE performance was measured (Table 3).

As can be seen from the table, the claimed design MFRE and the method of restoring its performance are highly reproducible, reliable during operation, environmentally friendly (chemicals are not used for washing), are relatively simple and accessible to consumers.

Table
Examples of the implementation of the proposed method for restoring the performance of prototypes of the membrane ultra-microfiltration roll element (MFRE) №№ Names of indicators of MFRE and regimes
implementation of the recovery method
health Data for examples No. 1-10 1 2 3 4 5 6 7 8 nine 10
(cartridge) 1 The parameters of the tested samples MFRE ^x) 1.1 outer diameter, D mm 60 60 60 60 90 90 90 90 190 1.2 length mm 300 400 400 300 400 400 400 300 600 1.3 filtration surface area, m ² 0.5 0.6 0.6 0.5 1,2 1,2 1,2 1,0 16 0.5 1.4 type of used semi-particles. membranes - cellulose acetate ultrafilter + - - - + - - - - - phenylone based ultrafilter - + - - - + - - - - cellulose acetate microfilter - - + - - - + - + - microfilter based on hydrophilized fluoroplastic - - - + - - - + - + (cartridge) 1.5 initial performance MPRE for purified water, l / h 40 45 100 90 90 100 250 230 3500 90 1.6 the performance of MFRE (according to the system of Claim 1.5) before flushing (contaminated MFRE), l / h twenty 25 fifty 40 fifty 60 100 100 2000 10 2 Recovery of performance of MFRE - 2.1 The first stage of flushing. The filtrate obtained from the system of Claim 1.5 was used. the flow rate of the filtrate for washing, m ³ / hour 0.5 0.55 1,0 1,0 1,0 1,0 1,5 1,5 10 - filtrate washing time, sec 5 2 nine 10 10 5 5 5 2.2 The second stage of flushing. The composition of the water-air mixture: - water, volumetric part 1 1 1 1 1 1 1 1 1 - air, volumetric part 10 10 twenty twenty 10 10 twenty twenty thirty Air-water supply mode: - flow rate of the mixture, m ³ / hour 1,0 1,0 1,0 1,0 2.0 2.0 2.0 2.0 fifteen - time flushing with water-air mixture, sec 2 2 3 3 2 2 3 3 10 3 MFRE performance (according to the system of clause 1.5) after restoration of working capacity, l / h 35 40 80 75 85 90 180 160 3000 4 The resulting filtrate volume, l / for the period of full operation 10,000 500 ^x) The tests were carried out in a module having an inner diameter of D _m = 65 mm, 100 mm, 200 mm, respectively, examples No. 1-10

Claims (3)

1. Membrane ultrafiltration roll element, consisting of a filtrate-discharge perforated tube, spirally wound thereon through a turbulent mesh of membrane bags containing a drainage web and a semi-permeable membrane, and a sealing cuff located on one of the ends of the roll element, characterized in that the drainage web consists of two sheets superimposed on each other, the grooves of which are located inside the double layer and form common drainage channels, on the outside the roll element has a free the outlet of the turbulators separating the membrane bags and wrapped in a turbulatory mesh, the sealing sleeve is located on the opposite end of the roll element relative to the supply of the filtered fluid and has an outer diameter selected from the ratio D _m = D + (5 ÷ 10 mm), where D is the outer diameter of the roll element, mm; D = d + 2δ, d is the average outer diameter of the roll element after winding the membrane bags, mm; δ is the thickness of the layer of the outer turbulence grid, mm. 2. Membrane ultrafiltration roll element according to claim 1, characterized in that the membrane bags have a shape close to square. 3. A method of restoring the operability of a membrane ultramicro-filtration roll element having a structure in accordance with paragraphs 1 and 2 by washing with a liquid, feeding it along the line of movement of the filtered medium, characterized in that the washing is carried out in two stages: at the first stage, the roll element is washed with a filtrate feeding it countercurrently through the filtrate outlet line with a flow rate of 0.5-10.0 m ³ / h for 2-10 s, at the second stage, the roll element is treated with a water-air mixture in a ratio of 5-30 vol. hours of air per 1 vol. including water, feeding this mixture along the line of movement of the filtered medium with a flow rate of 1.0-15.0 m ³ / h for 2-10 s.