RU2392039C2 - Membrane filtering roll element - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to design of membrane filtering roll elements intended for separation of liquid mediums. Membrane filtering roll element consists of filter discharging perforated tube, sealed adjacent membrane packs and sheets of turbulence promoter. Membrane packs are displaced relative to each other. Besides membrane packs with total number n are arranged in the form of two groups arranged alternately with number n₁ and n₂ of membrane packs accordingly, at the same time value of membrane packs displacement inside each group and value of membrane packs displacement of the second group relative to membrane packs of the first group are different values. Value of displacement between membrane packs of the second and first groups makes

where d is diametre of filter discharging tube. Length of membrane packs of the second group is less than length of membrane packs of the first group by value δ-Δ, where Δ is displacement of membrane packs relative to each other between membrane packs inside every group.

EFFECT: invention makes it possible to increase efficiency of membrane element, to achieve repeatability of parametres and stability of membrane element operation.

2 ex, 1 tbl, 1 dwg

Description

The invention relates to the design of devices used in membrane technology, namely membrane filtering roll elements (hereinafter - MFRE), and can find wide application in the technique of separation of liquid media in various industries, in particular for desalination of brackish and sea waters, in wastewater treatment industrial production, the concentration of biologically active products, enzyme solutions, dairy products, proteins, curd and cheese whey, skim milk, for the separation of organic compounds from inorganic in solutions, water softening and surface water purification from low molecular weight substances and drinking water in household appliances. Depending on the areas of use, on the nature and properties of the media to be separated, various types of semipermeable membranes, including micro-, ultra-, nano-, reverse osmosis membranes, are used in the manufacture of MFRE. The use of appropriate semi-permeable membranes of the highest quality is insufficient to ensure high technological and operational characteristics of MFRE. The high performance indicators of MFRE are also determined by the design of their individual units and elements, as well as the technology of manufacturing MFRE. It is to the designs of individual units of MFRE that the modern technique for separating liquid media on semipermeable membranes places ever higher demands on reliability, reproducibility of properties, and service life.

The well-known designs of MFRE differ in both the general design and the features of the individual nodes and elements included in it - semi-permeable membranes, membrane bags, turbulators, drains, as well as the technology of winding membrane bags and turbulators on the filter tube and the methods of sealing them (Japanese Application No. 54 - 151571, 52 - 5431, 54 - 149384, 54 - 149383, 53 - 124179; U.S. Patent Nos. 3,966,616, 3,417,870, 4,235,723, 5,538,642; USSR Copyright Certificates No. 1205359, 1213100, 1595553).

To improve the operational properties of MFRE, in particular, to increase their productivity and selectivity, there are several common techniques.

An increase in the selectivity of the roll elements is achieved: 1) through the use of more selective membranes, 2) by reducing the concentration polarization on the surface of the membranes, which, in turn, is achieved by increasing the turbulization of the initial flow due to a change in the hydrodynamic conditions of separation or through structural changes in the pressure channels.

An increase in the performance of MFRE is possible due to: 1) an increase in the effective surface of the separating membrane, which is achieved, first of all, by changing (increasing) the geometrical size of the element, 2) increasing the specific productivity of the membranes used, and 3) reducing the hydrodynamic resistance in the filtration channels of the membrane packages of MFRE.

The basis of the claimed invention is the principle of reducing the hydrodynamic resistance in the filtration channels of the MPFE membrane packages to increase its productivity. The hydrodynamic resistance in the drainage channel is proportional to its length. Therefore, a decrease in the length of the drainage channel leads to a decrease in the hydrodynamic resistance, an increase in the driving force of the process (the difference in pressure applied to the outer side of the membrane and the pressure of the hydrodynamic resistance of the filtrate outlet channel) and, as a result, to an increase in the performance of the MFRE.

This technique in the manufacture of MFRE is used by Film Tec (Technical Bulletin Form No. 609-00485-704, published on the company website www.filmtec.com). The eight-inch diameter MFREs manufactured by this company consist of 30-31 membrane bags 75-77 cm long, with all membrane bags located around and all in contact with a filtrate outlet tube of the same diameter (38 mm). The disadvantage of these technical solutions is the possibility of distortion of the correct cylindrical shape of the MFRE when it is assembled at the stage of spiral winding, in particular, the possibility of violating the coaxiality of the filter tube and the MFRE itself, which leads to the complexity of the operation of these packages in the MFRE. Such an undesirable fact is explained by the objective difficulty in arranging a large number of membrane packets around a filtrate outlet tube of a certain diameter. So, in this case, the offset of the packets relative to each other should be

что довольно затруднительно на практике.

which is quite difficult in practice.

, которое является зависимой величиной от наружного диаметра фильтратотводящей трубки, толщины мембранного пакета вместе с толщиной листа дренажа и числа мембранных пакетов. Число мембранных пакетов в МФРЭ устанавливают в зависимости от требуемых показателей фильтрующего элемента.The closest technical solution to the claimed is the design of MFRE according to the patent of the Russian Federation No. 2225187, publ. in 2005, which consists of a filtrate-discharge perforated tube with holes for receiving the filtrate coming from the drainage sheets and spirally wound membrane packets adjoining each other through sheets of turbulator, sealed (with glue) from the turbulence (pressure) zone. A feature of the solution according to the prototype was that the membrane packets are placed relative to each other with an offset

, which is a dependent value on the outer diameter of the filtrate outlet tube, the thickness of the membrane bag along with the thickness of the drainage sheet and the number of membrane bags. The number of membrane bags in MFRE set depending on the required performance of the filter element.

The disadvantages of MFRE according to the solution of the prototype are the limited ability to increase the number of membrane packages, which entails a limited increase in productivity, insufficient reproducibility of properties when increasing the number of membrane packages due to the appearance of a violation of coaxiality when assembling MFRE - the so-called “ellipse” effect, a change in operational properties during filtering.

The essence of the invention is as follows.

An object of the invention was the development of the design of MFRE, providing for the possibility of a new and efficient arrangement of its individual nodes.

The technical result of the invention is to increase the performance of MFRE while maintaining other conditions, reproducibility, stability of operation of MFRE, ensuring the absence of ellipse with an increase in the number of membrane packages.

According to the invention, MFRE consists of a perforated perforated tube 1; sheets of turbulator 2, spirally wound on a perforated tube 1, forming pressure channels (not indicated), semi-permeable membranes 3, folded in half, inside of which there are sheets of turbulator 2; membrane packs, which are divided into two groups: membrane packs of the first group 4 and membrane packs of the second group 5. Membrane packs of the first group 4 are in direct contact with the perforated perforated tube 1 provided with holes, and the membrane packs of the second group 5 are shifted relative to the membrane packs of the first group 4 a few centimeters (δ), providing direct contact with the permeate perforated tube 1 only of its drainage sheet 6.

To achieve a technical result, you can either increase the shift between the membrane bags within each group (value "A"), for example 2 times, which greatly simplifies and ensures the stability of the production of MFRE from these packages, or allows you to increase 2 times the number of packages while reducing their length also 2 times (while maintaining the value of "Δ"). In this case, direct contact with the perforated filtrate tube 1 of the drainage sheets of all packages is ensured and the requirement of coaxiality and the cylindrical shape of the MFRE are maintained.

The drawing shows a schematic representation of the claimed MFRE, where:

1 - perforated perforated tube

2 - turbulator sheets

3 - semipermeable membranes

4 - membrane packets of the first group

5 - membrane packs of the second group

6 - drainage sheets

l ₁ - the length of the membrane package of the first group

l ₂ - the length of the membrane package of the second group

D - diameter MFRE

d is the outer diameter of the filtrate outlet perforated tube

n is the total number of membrane packets

n ₁ - the number of membrane packets of the first group

n ₂ - the number of membrane packets of the second group

δ is the shift of the membrane packets of the second group relative to the packets of the first group

Δ is the shift of the membrane packets relative to the membrane packets within each group

The following abbreviations were also used for further calculations:

S _m - the thickness of the semipermeable membrane in the membrane package

S _t - turbulizer sheet thickness

S _d - the thickness of the drainage sheet

S _p - the thickness of the membrane package

In accordance with the claimed invention, the membrane packets of the second group should be shorter than the membrane packets of the first group by δ-Δ.

The thickness of the membrane package is:

S _p = 2S _m + S _t + S _d ,

n = n ₁ + n ₂

n ₁ = n ₂ + m, where m = 0 or 1; moreover, m = 1 if n is an odd number, and m = 0 if n is an even number.

l ₂ = l ₁ -δ + Δ,

The interval 3-10 is established by the authors experimentally and determines the multiplicity of the shift of packets of groups 1 and 2 relative to each other relative to the shift of packets relative to each other within each of the groups.

When the interval value is less than 3, the difference in the values of δ and Δ for the technological process of manufacturing roll filter elements and their properties becomes insignificant, i.e. δ → Δ.

The value of the interval greater than 10 leads to an unreasonable loss of the active area of the membrane in the element by reducing the length of the packets l _{2 of the} second group.

It should be noted that δ is determined in each case depending on “d” and “n”.

Although the invention is universal in nature, cases where Δ≤15 mm are of practical importance.

The inventive MFRE operates as follows.

The initial liquid to be separated is fed into the pressure channels formed by the sheets of the turbulizer 2, under the action of the working pressure, a part of the liquid, which is a filtrate, penetrates through the semipermeable membrane 3 and enters the drainage channels formed by the sheets of drainage 6, which has longitudinal grooves located perpendicular to the perforated perforated tube 1. The filtrate passes through the indicated grooves to the filtrate outlet perforated tube 1, getting inside it through the holes, and then it is removed from M EED. The concentrate is discharged from the opposite end of the MFRE.

The following are specific examples of the manufacture of MFRE taking into account the mathematical formula used in the claimed technical solution.

Example 1. (column "2" of the table)

A perforated filtrate outlet tube (1) with a length of 1016 mm and an external diameter of 20 mm is installed in the clamps of the machine for winding roll elements.

Using a heating tool, drainage sheets 6 with a width of 1000 mm are welded to the filtrate outlet pipe. A first packet of the first group 4, length L ₁ = 400 mm, consisting of half double-permeable reverse osmosis membrane 3, inside which sheets of a turbulizer 2 are located, are placed on the drainage tube 1 welded to the filtrate outlet tube 1 and the upper half of the bent semi-permeable membrane 3 is 8 mm longer. A 400 mm long drainage sheet is laid on the first membrane bag. Then, on the three sides of the membrane package (except for the side facing the filtrate outlet tube), an adhesive composition is applied. The next membrane package (the first package of the second group 5) of length L ₂ = 376 mm is laid on the previous one with a shift of δ = 32 mm from the side of the first package of the first group facing the filtrate outlet pipe. A 400 mm long drainage sheet with a shift Δ = 8 mm from the side of the first packet of the first group facing the filtrate outlet pipe is laid on the first packet of the second group. The application of the adhesive composition is repeated. The second packet of the first group is laid flush with the drainage side facing the filtrate outlet pipe. The laying of a 400 mm long drainage sheet is repeated, now on the second membrane bag of the first group, the adhesive composition is repeated, the laying of the second packet of the second group with a length of L ₂ = 376 mm with a shift of δ = 8 mm from the side of the second packet of the first group facing the filtrate outlet is repeated handset, etc. before laying the seventh package of the second group (fourteenth of the total number of all packages).

The drive of rotation of the filtrate discharge tube is turned on, stacked bags are wound on the filtration discharge tube. The resulting cylindrical body has an external diameter of 100 mm, a deviation from the theoretical cylinder of 0.3%.

When testing the obtained roll element on a bench at a pressure of P = 1.05 MPa, the filtrate productivity was 430 l / h.

Example 2. (column "6" of the table)

Similar to the previous except that:

1. instead of a reverse osmosis membrane, a nanofiltration membrane was used;

2. the outer diameter of the filtrate outlet pipe is 40 mm;

3. The length of the package of the first group is 550 mm;

4. the length of the package of the second group is 505 mm;

5. shift δ = 50 mm;

6. shift Δ = 5 mm;

7. The total number of packets is 40.

The resulting cylindrical body has an external diameter of 200 mm, a deviation from the theoretical cylinder of 0.3%. When testing the obtained roll element on a bench at a pressure of 1.5 MPa, the filtrate productivity was 3150 l / h.

The applicant, together with the inventors, manufactured and tested prototypes of MFRE with an outer diameter of 100, 200 and 400 mm and a length of 600 and 1016 mm.

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

Data on samples made in accordance with the decision of the prototype 1, 3, 5, 7, 9, 11 and samples 2, 4, 6, 8, 10, 12 - in the initial period of their testing, on samples 4 *, 6 *, 8 *, 12 * - after life tests for ≈400 hours.

As can be seen from the table, the prototypes are distinguished by increased relative to the samples in accordance with the decision of the prototype cylindrical shape and higher performance. Moreover, the increase in productivity is enhanced by the transition from MFRE, made on the basis of semipermeable membranes with conditionally low specific productivity (reverse osmosis, nanofiltration) to semipermeable membranes with high specific productivity (ultrafiltration and, especially, microfiltration).

Bibliographic data

1. RF patent №2245187, publ. in 2005 (prototype).

2. Film Tec website www.filmtec.com.

Claims (1)

A membrane filter roll element consisting of a perforated perforated tube, sealed adjacent membrane bags, inside which are located drainage sheets spirally wound on a perforated perforated tube, and turbulator sheets located between the membrane bags, with the membrane packages displaced relative to each other, characterized in that the membrane packets with a total number n are made in the form of two groups arranged alternately, moreover, the membrane e packets of the second group in the amount of n _{2 are} made with an offset relative to the membrane packets of the first group in the amount of n ₁ , while the displacement of the membrane packets within each group and the displacement of the membrane packets of the second group relative to the membrane packets of the first group are different values, the displacement of the membrane packets the second group relative to the membrane packets of the first group is

,
where d is the diameter of the filtrate outlet tube, while the length of the membrane packets of the second group is less than the length of the membrane packets of the first group by δ-Δ, where Δ is the displacement of the membrane packets relative to each other between the membrane packets within each group, and the number of membrane packets used in the first group is determined from the calculation of n ₂ + m, where m = 0 or 1, and m = 0 if n is an even number, and m = 1 if n is an odd number.

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