DE2618482A1 - FILTER - Google Patents

Description

PATENT Attorneys £ 7 APR 1976

DR.-ING.- H. FiNCKE D I P L. - I N G. H. B O ri R DIPL-ING, S. STAZGER DR. Rer. no. R. KNEISSL MÜLLERSTSASSE 31

8000 M Cl N C H E N 5

Folder 23 969 ICI Case Nr.Du.27784

IMPERIAL CHEMICAL INDUSTRIES LIMITED London, England

filter

The invention relates to filters and, more particularly, to filters useful for removing solid particles from large volumes of fluid with low viscosity, such as gases or water, are suitable.

When filtration processes are usually carried out, the fluid to be filtered is passed through a porous membrane or mass passed, the pores of which are generally smaller than the particles to be removed. It is still general known to separate solids from the fluid phase by using physical forces, for example centrifugal forces. In this method, the energy required to separate the particles from the fluid is relatively large. if porous filter media are used, it becomes even larger,

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when the particles collect on the filter surface. This either reduces the filtration rate or there is a greater pressure difference between the feed and Drainage surfaces of the filter medium required. This-' there are limits to the material that can be used. When high pressures occur, it is necessary to remove molten, To use porous, ceramic products or classified sand layers in order to increase the forces or strengths create, which are necessary for the counteraction against these pressures.

The common way to remove a filtered solid from the filter in a liquid filtration process is the backwash. This can be an expensive operation, especially when filtering a large volume of liquid and when backwashing occurs frequently. Many filter elements cannot be backwashed satisfactorily are and must be thrown away.

According to the invention, many of these difficulties and disadvantages are eliminated. The invention includes the following Characteristics:

(1) According to the present invention, there is a method of filtering Large volumes of fluid created, which initially works with a very low pressure drop across the filter medium.

(2) The mass of particles removed does not adhere firmly to the filter surface, and the time it takes for a substantial one Pressure drop occurs is surprisingly long.

(3) The filter element used is easily backwashed and there are only small amounts of fluid and one a short time is required for this purpose.

(4) The passageway per unit surface area is considerably higher than that of previously used units.

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The invention relates to a filtration device, which comprises the following parts: a chamber, a hollow, porous filter element so mounted in the chamber is to create an annular space, sealing means for isolating the annular space from the interior of the element, means for feeding the fluid into the "annular space" and means for discharging it of the filtered fluid from the interior of the element, the filter element being provided with a rough surface and the device is so constructed and configured that the fluid in the annular space is above the surface of the filter element flows.

There are a number of ways to ensure that the fluid in the annular space is above the surface of the filter element flows. The annular space can be equipped with a shaft below the filter into the through the inlet the fluid is introduced, so that the latter must rise vertically out of the well before it is with the Filter element surface comes into contact. A second possibility is that the inlet is arranged so that the out the fluid coming out of it is passed directly over the surface of the filter element. A third possibility is to arranging the inlet so that the fluid is dispensed in a direction perpendicular to the surface, but one Attaches baffle therebetween so that the direction of movement of the fluid is changed so that it over the surface of the Filter element flows.

It is also essential that the surface of the filter element be rough. The preferred form of device contains a hollow, cylindrical filter element which is mounted centrally within a cylinder chamber. Suitable elements of this type can be obtained by coating particles of compact shape with a liquid which

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solidifies and bonds the particles together, whereby If an insufficient amount of liquid is used to fill the spaces between the compacted particles, the mixture Pour into a cylindrical mold and solidify or solidify the liquid.

The particles can be organic in nature, for example particles made of a polyamide, polyester or polyolefin, However, they are preferably inorganic and in particular of mineral origin. The term "compact form" means that the longest dimension should not be more than twice the other dimensions at right angles to it and that the Surfaces are essentially free of protrusions. The preferred particles are granite, flint or sand particles, it is particularly preferred to use a mixture of two different sizes of sand or a mixture of sand and use either flint or granite. The size of the particles in this context can be determined by the passage through and the retention on BSS sieves can be defined.

The liquid binder can be inorganic, for example a cement / water mixture; however, it is preferred an organic binder such as an unsaturated polyester, epoxy resin, or polyurethane binder.

By using a mixture, the sand or other compact mineral particles with two or more different ones Sizes, the porosity and surface roughness of the filter element can be within a wide range can be varied. It has been found in practice that uniform mixtures of sand with different sizes are preferred in the manufacture of the filter elements, since this results in a uniform filtration flow on the one hand is obtained over the surface of the filter element and, on the other hand, also achieves a uniform strength of the material.

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Although systems with three or four different particle sizes can be used, as described for example in GB-PS 1,373,214, it is preferred to use mixtures to use from two sizes, each size in an amount of AO to 60 wt.%, based on the total mixture, is available. This effect is explained using the following tables, where the relative porosities and compressive strengths of 7.6 cm square cubes of compositions made from the mixtures will. The resin used to bond the particles is a mixture of an oxypropylated toluenediamine having a MW von 460 and Suprasec DN, which is a commercially available diisocyanatodiphenylmethane and other poly (isocyanatophenyl) polymethylenes together with 20% by weight of methyl ethyl ketone and has an NCO value of 250 with an NCO: OH ratio of 1: 1. The amount of resin used is between 10 and 5% by weight, based on the particles.

To make the cubes, the particles are in. Mix well when dry, then add the resin and mix for an additional 5 to 10 minutes to ensure that the particles are well coated. The particles are then placed in a 7.6 cm cube form which is tamped several times to allow the particles to settle, and then excess material is removed from the surface, which is slightly pressed to make a smooth , upper surface is obtained. The cube is hardened by standing at room temperature for 2 days or by heating to 110 ^° C. for 2 hours.

Compressive strengths are measured on a Farnell Compressive Strength Tester, Row 500, definitely.

The porosities are determined in a relative manner using the following test procedure. Four surfaces

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surfaces of the cube are covered with a water-repellent polyurethane coating coated, leaving two opposing surfaces * exposed. The cube is arranged so that the free surfaces are horizontal, i.e. at the top and at the bottom. A 15.2 cm long cylinder 6.35 cm in diameter is placed on top. The rest of the surface outside the cylinder is then sealed in a similar manner to the sides of the cube. Water is poured into the cylinder and at one Maintained a depth of 10.16 cm. The one from the lower part of the The water running off the cube is collected and weighed. In the column in which the porosity is given, the cm measurement on the inner cross-sectional area of the cylinder.

Table I.

Particles - Granite, sizes 5.0 to 6.3 mm and 0.5 to 1.0 mm Resin: Particle Ratio = 15: 1

ratio of

5 to 6.3 mm: 0.5 to 1 mm

0: 100 10:90 20:80 30:70 40:60 50:50 60:40 70:30 80:20 90:10 100: 0

Outside the ratio of 40:60 to 60:40, the distribution of the smaller particles is less homogeneous. the The following tables relate to mixtures of equal weights of the two sizes in question.

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porosity Compressive strength l / h / cm2 kg / cm2 3.9 74.3 3.7 110 3.0 118 3.9 140 1.9 164.5 2.0 161 2.7 134 7.1 146 7.1 144 8.9 63 17.8 62

- 7 - Resin part
chen-ver
ratio porosity
l / h / cm2 2618482 8th Druckfe
sturdiness
kg / cm * ¹ Table II 1:20 5.08 9 74 Granite particles 1:15 3.96 0 102 Small size
well 1:15 2.37 7th 157 Big size
mm 2.0-3.35 1:15 2.09 porosity
1 / h / cEi ² 7th 133 5.0-6.3 1.4-2.0 1:15 1.62 17, 4th 141 Il 0.5 - 1.0 1:15 0.85 8th, 1 108 Il 0.3-0.41 1:15 4.18 2, 7th 111 η 0.25-0.33 1:15 4.44 O, 4th 97 It 0.21-0.25 1:10 2.54 O, 7th 129 η 0.5 - 1 1:10 1.04 0, 5 129 2.0-3.35 0.21-0.25 1:10 5, 132 η 0.25-0.355 Table III O, 0.5 - 1.0 0.21-0.25 (Resin: sand ratio = 1:20) 1, η 0.09-0.21 Small size
τητη O, Compressive strength
kg / cm ² η 1.4-2.0 O, 1.0 - 1.4 171 Sand particles 0.85 - 1.0 Big size
mm 0.71-0.85 not determined 2.0-3.35 0.60-0.71 π 0.30-0.60 If 1.0 - 1.4 It 0.85 - 1.0 It 0.71-0.85 dd 0.50-0.60 1.4-2.0 Il It 161 π 165 172 180 182 151 165 143

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- 2618482 Compressive strength - 8th Table IV kg / cm ^ Granite (Flintag) - sand mixtures 169 Big size Small size Resin: Particle Ratio = 1:20 189 now τπτη porosity 172 3.35-5.0 1.4-2.0 l / h / cm ² 199 ¹¹ 1.0-1.4 3.23 267 "0.85-1.0 2.22 "0.71-0.85 1.11 "0.50-0.60 1.18 0.83

From these tables it can be seen that for all series with a constant size of the large particles the Porosity decreases as the size of the smaller particles increases and those with larger particles have higher porosity exhibit. It is thus possible to manufacture composite materials with similar porosities, their surfaces but varying degrees of "roughness", roughly the size of the larger particles used to make the Composition used corresponds.

The present invention will now be explained with reference to the accompanying drawings, in which FIG. 1 shows a cross section a filter device according to the invention is shown, in particular for removing suspended solids from Water is suitable, and Fig. 2 is a plan view of the filter device, seen from above, together with that associated therewith Shows feed piping and backwash assemblies.

In the drawing, 1 denotes a cylindrical housing screwed thereto end plates 2 and 3, an outlet pipe 4, which extends into the housing and expands to form the inner cylinder 5, contains. An opening 6 in the The wall of the chamber gives an inlet opposite the wall of this inner cylinder. The top surface of this Cylinder contains a circular hole 7 through which a

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"y -

is surrounded by a small edge which contains a sealing ring 8.

A porous filter element 9 that contains a mixture of two sizes of sand and / or granite or flint and that bound by polyurethane resin in a manner similar to the previously described cubes, and has the shape of a hollow Has cylinder is mounted centrally within the housing, the lower end rests on the seal and the upper end is sealed by a steel plate 10 and a gasket. A threaded rod 12 goes through a hole in the plate, and a thumb screw 13 and sealing washer 14 cause the plate and the filter element against the seals 8 and 11 can be sealed.

The lower end of the housing forms a shaft. The plate 3 is equipped with a drain pipe 15. A Flood relief valve 16 is fitted in the plate at the top of the housing.

The opening in the housing for the outlet pipe and the opening 6 are surrounded by flanges 17 and 18, which with Bolts (not shown) are equipped to allow the fitting of the inlet and outlet pipes 19 and 20, Each of which has a valve tube 21, which serves as a manometer point, and a valve tube 22, which serves as a sampling point serves, is equipped. The tubes 19 and 20 are via the valves 23, 24, 25 and 26 with the inlet supply of the to filtering fluids and connected to a collection point for the filtered fluid. A tube 27 with a valve 28 connects the inlet and outlet pipes at locations between valves 23 and 24 and the valves, respectively and 26.

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A valve 29 is fitted into the extraction pipe 15.

During operation, the valves 28, 29 and those of the pipes 21 and 22 are closed and the valves 16, 23, 24, 25 ' and 26 are opened. The liquid is pumped onto the filter and air in the space between the filter element and the housing escapes through the valve 16 until the Space is filled. Then the valve 16 is closed.

When the filtration takes place in the usual way, the pressure difference between the tubes 21 is usually smaller than 0.35 kg / cm. In most cases, the material to be filtered from the liquid collects on the surface of the filter element and falls into the shaft. An increase in pressure on the filter element is usually a sign that the shaft is full and must be opened. To do this, open the drain valve 29. At the same time, this can be done on the Material adhering to the surface of the element, provided it is not greasy, can be removed by briefly backwashing. In addition reverse flow is used by closing valves 23 and 26 and opening valve 28. That falls Material also into the shaft and can be via the extraction valve removed.

Successful operation of the filter seems to depend on the formation of turbulence in the liquid, caused by the flow of the latter on the roughened side of the filter element. Until this turbulence forms, the performance of the element is greatly reduced. The turbulence is caused by various factors the most important of which appear to be the following:

(1) flow rate of the supplied liquid,

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"Roughness" of the surface of the filter element and (3) the pressure of the liquid supplied.

It has been shown that many of the binders used to manufacture the filter elements affect the behavior of the Do not affect the elements. The selection of the binding agent is made in terms of its cost and / or its durability properties under operating conditions. At a aqueous filtration process, an epoxy resin and particularly preferably a crosslinked polyurethane resin is preferably used. A resin is preferably used which is obtained from a polyether as the hydroxyl component, for example the oxypropylated one Reaction product of glycerol, trimethylolethane or trimethylolpropane, or of an aliphatic or aromatic one Diamine, e.g., tolylenediamine.

It has been shown that for the filtration of solids the best results are obtained from water when the pressure drop between the circular space and the interior of the element on the order of 0.035 to 0.07 kg / cm lies. The separation efficiency is reduced in the range of 0.14 to 0.35 kg / cm of pressure drop. Above the latter In terms of value, the separation occurs only to a small extent, i.e. it proceeds relatively slowly. To achieve the full performance it is important to balance the porosity of the filter element with the desired flow rate of the fluid, so that a pressure drop of 0.035 to 0.07 kg / cm between the annular space and the interior of the element takes place.

Although these values are not completely independent of the surface area of the filter element, this holds true the following relationship between the porosity determined as above described, and the flow velocity for filter elements with an area of 0.0929 to 0.557 m and at a

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Operating at an inlet pressure of 3 _f 52 kg / cm to get the required pressure drop:

Porosity (l / h / cm) flow velocity (l / h)

1.8 11 360

4.3 22 710

4.7 26 500

6.0. '34 070

If the inlet pressure or the flow rate deviates from the optimal values for the selected porosity, the performance of the filter element decreases. It is therefore important in operation that the inlet pressure or flow rate deviates slightly from the specified values, preferably not more than 5% of these values.

It has been found that when flow rates below 11,360 l / h are required, the mixture will run out Sand particles that are required to achieve the corresponding porosities of 2 l / h / cm and a small size possesses, results in surfaces that are not rough enough to be effective. This can solve this problem be that one applies an outer layer of larger particles to the filter element, for example by one applying such a layer of particles with a diameter of 5.0 to 6.3 mm to the outer surface of the element, when using the minimum effective amount of binder. Other means of applying a layer of larger particles in close proximity to the outer layer of the element are also effective.

The results obtained with the filters of the present invention are explained below.

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example 1

A mixture of equal parts by weight of Garside sand with 1.0 to 1.4 mm and 1.4 to 2.0 minutes is 5% by weight oxypropylated tolylenediamine / Suprasec DN resin, as mentioned above, mixed and cut into a 62 cm high and 2.54 cm thick Cast hollow cylinder shape with an outside diameter of 25.4 cm. This cylinder has a surface of 0.49 m The mixture poured into a cube has a porosity of determined in the same manner as described above 4 l / h / cm. This filter element is in a filter chamber of the type described above with an inner diameter of 55 »88 cm fitted so that the annular space has a radial dimension of about 15.24 cm.

At an inlet pressure of 3 »52 kg / cm, water is pumped through at a rate of 18,930 to 22,710 l / h. Included the solids content is reduced from 1.9 ppm to 0.36 ppm. At an inlet pressure of 0.42 to 0.56 kg / cm, the solid becomes content, even with a flow of 26,500 to 30,280 l / h, only reduced from 8.6 to 5.4 ppm. '

Example 2

In a smaller scale device, a

element made in the same way is used. It owns

2 but only a surface of 0.12 m. Operation is at an inlet pressure of 3 »52 kg / cm with less than 7 570 l / h. The solids content is reduced from 2.4 to 1.6 ppm « The filter contains a 30.5 cm high element with an outer diameter of 12.7 cm and is in a chamber fitted with a radial distance of 7.6 cm. When operating at 1.48 kg / cm pressure, 7570 l / h, the content of suspended Solids decreased from 1.8 to 1.3 ppm. For an element with similar dimensions but a rougher surface, that of flint particles with a size of 5.0 to 6.3 mm and sand with a size of 1.4 to 2 mm with a

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Epoxy resin is produced, the suspended solids content is reduced from 1.25 to 0.2 ppm. This The mixture has a porosity of 4 l / h / cm. The resin is a mixture of 100 parts by weight Epophen ET-2 and 65 parts by weight EHT-3 hardener (Borden Chemical Co.). The mixture is cured for 4 days at room temperature.

Example 3

In a device with the dimensions of the device of Example 1 is fitted a filter element which has been made from equal parts by weight of flint particles of 3.35 to 5.0 mm and sand of 1 to 1.4 mm and which has a urethane binder as above described has been bonded at a 1:20 binder: aggregate ratio. This element is used to filter river water containing 400 to 500 ppm solids at an inlet pressure of 3.52 kg / cm ² and a rate of 18,930 to 22,271 liters / hour. The effluent contains 8 ppm solids. Drainage is required at daily intervals. 5.7 million liters flow through the filter before the experiment is terminated. Then the element is checked. You can see that it is obviously unchanged.

In another attempt, the runoff water contains 9 ppm solid material. This water comes with a laboratory sample from distilled water on a Coulter Electronics Limited particle counter compared (in each case two samples). The following results are obtained.

Volume: 0.05 ml

Particle size, / U Distilled water Filtered water

5.03 30, 32 80, 72

3.99 52, 52 146, 135

3.17 112, 107 272, 246

2.51 195, 190 582, 546

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- 15 particle size, / U Distilled water Filtered water

1 B e i s ρ , 99 4th 275 237 1138, 1147 1 , 58 589, 574 3192, 3119 1 , 26 7019 , 8017 18021 , 16204 i e.l

Mm, a mixture of equal parts by weight limestone particles with 6.3 to 8.0, and is 0.71 to 1.0 mm with 6% by weight epoxy resin and a hardener in a ratio of 10:. 7 and mixed in a high and 62 cm 2 , 5 cm thick hollow cylindrical shape with an outer diameter of 25.4 cm. This cylinder has a surface of 0.49 m ² . The mixture cast into a cube has a porosity of 2.3 l / h / cm, determined as above. A uniformly rough surface is obtained by applying a single layer of 6.3 to 8.0 mm limestone particles to the surface of the cylinder. An epoxy adhesive is used for this.

From Fig. 1 it can be seen that for an element with

a porosity of 2.3 l / h / cm the optimal conditions for the flow rate are 3200 g / h.

With water pumped through this unit at 3000 g / h with an inlet pressure of 4.22 kg / cm, the Solid content reduced from 8.8 to 3.5 ppm. One observes less than 0.07 kg / cm differential pressure on the element.

Water is pumped through the same unit at 3000 g / h with an inlet pressure of 2.81 kg / cm. The solids content is reduced from 35 to only 31 ppm.

With water pumped through the unit at 4800 g / h with an inlet pressure of 4.22 kg / cm, the solids content is reduced from 52 to only 44 ppm.

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The epoxy resin used in the construction of the element used in this example is Epophen EL and Hardeners EHL3, which are used in a ratio of 10: 7.

The filter described above is suitable for removing suspended particles from aqueous media. Such Applications include, for example, the removal of suspended inorganic and organic materials from water for manufacture potable or technical qualities of water for use in boiler feeders or feed waterers for aqueous processes or for the treatment of aqueous effluents to remove undesired inorganic or organic solid residues. Other uses are the removal of small amounts of suspended solids aqueous solutions of chemicals during chemical treatment or removal of suspended solids non-aqueous solvents.

The effectiveness and performance of the filters are very surprising as it removes particles from the liquid which have a much smaller diameter than the pores of the filter element. The inventive Filter behaves differently than known filters. It is believed that removing the solids from the formation depends on turbulence in the liquid in the annular space. If this assumption is correct, it should be possible be similar devices for removing particulate materials from gases such as flue gases from melting devices, boilers or cement plants, to use.

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Claims (8)

- 17 claims 1 .J Filtration device, characterized by a chamber, a hollow, porous filter element which is arranged within the chamber so that an annular space is formed, a sealing device for insulation of the annular space from the interior of the element, means for supplying fluid into the annular space and means for withdrawing filtered fluid from within the element, the filter element having a rough surface is provided and the device is so built and designed that the fluid in the annular space flows over the surface of the filter element. 2. Filtration device according to claim 1, characterized in that it is a porous, cylindrical Contains filter element which is mounted centrally within the cylinder chamber. 3. Element for use in a filtration device according to one of claims 1 or 2, characterized through a hollow, open-ended cylinder with a porous wall of mineral particles attached to a synthetic resin. . 4. Element according to claim 3, characterized in that g e k e η η that it contains at least two classified particle sizes. 5. Element according to any one of claims 3 or 4, characterized in that it is a synthetic resin contains a polyurethane resin. 6. Element according to any one of claims 3 or 4, characterized characterized in that it contains an epoxy resin as a synthetic resin. 609847/0671 7. A method for removing solid particles from their suspensions in a liquid, thereby g e k e η η draws the liquid in an annular chamber of the filtration device as defined in claim 1, directs and the filtered liquid from inside of the filter element decreases, the porosity of the filter element being dependent on the flow rate of the liquid in such relationship is that a pressure drop of 0.35 kg / cm or less between the outside and the inside of the element arises. 8. The method according to claim 7, characterized in that the pressure drop is 0.035 to 0.07 kg / cm ² . patent attorney dr. -ing. H. fincke, dipl.-ing. H. βοη * OIFL'INQ. S. STACQEi ;, OR. rer. nat. R. KNElSSL 609847/0671