JPS6240048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter element for use in equipment used to filter or purify liquids. In particular, the present invention relates to an over-element having two types of winding layers on a central support core and a method for purifying liquids with this over-element.

In the prior art, certain liquid passing devices typically include a perforated cylindrical support core and a winding of strand material around the support core, as described in U.S. Pat. No. 1,751,000. including.
These over-elements are adapted to remove undissolved particles from the liquid as the liquid passes through the over-elements in a direction from the outside through the wrapped material and into the support core. Undissolved particulates are trapped in the wrapped material.

Other over-elements in the prior art have multiple layers of material wrapped around a central support core, the layers having varying densities. As described in US Pat. No. 3,680,709, the density decreases away from the support core. This is because the turns are tight close to the support core and taper outwards.

Prior art superelements having multiple layers, where the outermost layer is less dense than the innermost layer, can have drawbacks resulting from clogging tendencies, limited backwashing, and improper flow distribution. I understand. These disadvantages are particularly noticeable when prior art wrap-around elements are used to support precoats of particles in the size range of about 60 to 400 meshes. Precoated particles are typically particles of cation and anion exchange resins. These precoated superelements reduce the concentration of dissolved and undissolved impurities from a level of approximately 50 parts per billion.
Used to purify water by reducing it to less than 10 parts.

Prior art superelements that progressively decreased the density of the wound layers in the direction away from the central support core
As liquid passes through the over-element in a direction from the outer layer to the inner layer and then through the central support core during the use cycle, it can easily become clogged with particulate material penetrating toward the center of the wrapped layers. Due to the close spacing of the windings close to the supporting core, the flow of liquid through the over-element in the backwash direction is
It is difficult to achieve sufficient speed to dislodge and remove particulate matter trapped within the windings of the over-element.

According to the present invention, the over-element with a large number of wrapped layers improves the flow distribution pattern to facilitate back-cleaning of the over-element and to reduce the tendency towards clogging in the direction of the use cycle. The shortcomings of These advantages, according to the present invention, include a perforated tubular support core, an innermost layer of overmaterial disposed around the tubular support core, and an outermost layer of overmaterial disposed around the inner layer. It is obtained in a superelement having a layer. The outermost layer has the ability to trap smaller particles than the innermost layer. This ability expressed in terms of particle size is called the nominal particle retention number.

According to a preferred embodiment of the invention, the over-element has multiple layers of strand material and is adapted to be precoated with particles in the size range of 60 to 400 mesh. The filter element is usually arranged in a tank, through which the liquid to be purified is passed according to methods well known in the art.

In accordance with the method of the present invention, the liquid is purified by precoating a wrapper element constructed in accordance with the present invention with particles ranging in size from about 60 to 400 mesh. The liquid to be filtered is fed to the precoated filter element. Periodically, the over-element is backwashed to remove pre-coated particles and trapped impurities, and the over-element is pre-coated with a new layer of particles.

The layer closest to the support core, or the inner layer, has the highest nominal particle retention number and therefore the lowest density, and the layer furthest from the support core, or the outer layer, has the lowest nominal particle retention number and therefore the highest density. In such a wound layer structure, the outer layer has the ability to trap smaller particles than the inner layer, and the area of the permeable element used to pass liquid through the permeable element is substantially larger than the permeable element. restricted to the outer layer of That is, undissolved particles are collected in a relatively thin annular portion of the outer layer and do not penetrate into the inner layer. Therefore, when the backwash liquid is flowed back through the filtration element,
Removal of undissolved particles is facilitated because they remain adjacent to the outer surface of the over-element.
Limiting the excess area to a relatively thin annular portion is
It is particularly desirable when using the over-element in over-element equipment where the over-element is precoated with fine resin particles in the 600 to 400 mesh size range. In the pre-coated over-element according to the invention, the areas prone to clogging are substantially reduced, and undissolved particles are located below the outer surface of the over-element, making them difficult to remove by backwashing. It doesn't fit in tightly.

Also, if the flow rate of liquid through the over-element increases rapidly and the resin or other particles are forced through the outermost layer, the particles will become distributed throughout the layers of the over-element. In this way, some particles will be trapped by the winding layer as a result of taking a detour when passing through the over-element, but the opening area through which the liquid will flow is small enough to significantly impair the liquid-passing ability of the over-element. It won't happen. Particles passing through the outer or denser layer are distributed throughout the inner or less dense layer. The distribution of these particles in the inner layer does not reduce the flow rate to an extent that significantly reduces the ability of the element to pass liquid during the use cycle.

According to the invention, backwashing action is also improved since the outermost layer has a greater pressure barrier to backwash liquid entering from the support core than the innermost layer of strand material. The backwash liquid will therefore distribute itself evenly along the length of the over-element when faced with the large pressure barrier created by the outer layer.

Other advantages, objects and features of the invention will become apparent from the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.

Referring now to the drawings, and in particular to FIG.
10 is generally indicated. This device is covered by U.S. Pat. No. 3,279,608, assigned to the assignee of this application.
of the type shown and described in No. The filtration device 10 is adapted to receive and pass an incoming stream and to discharge a liquid or effluent stream.

The filter device 10 or tank is a generally cylindrical container made of steel having an outwardly convex top 11 and an outwardly convex bottom 13. The tank 10 is divided into an inlet zone 15 and a liquid zone 16 by a downwardly curved pipe plate 17 which is suitably fixed to the interior of the tank 10 by welding or the like. The inlet line 12 extends through the bottom 13 of the tank and communicates with the inlet zone 15 so that all incoming water passes directly into the inlet zone 15. An inflow pipe 12 is attached to a pipe plate 17 by welding or the like. In this way, direct communication between the inflow zone 15 and the liquid zone 16 is prevented.

Received within the inlet zone 15 are a number of filtration elements 18 through which the influent water passes before entering the liquid zone 16 and before being discharged from the filtration tank 10 through the outlet line 14. There must be. The over-element 18 is a toroidally wound over-element having multiple layers with constant particle retention capacity in accordance with the present invention. Each excess element 18 is
Overtank 10 with the holding device indicated by reference number 20
is maintained in the inflow zone 15 of the This holding device is
The overload element 18 is adapted to be releasably retained in overload seat means 30 attached to the tube plate 17. The excess element 18 is the excess tank 1
Excess tank 10 from the small manhole opening 22 of 0
It can be put into the tank or taken out from the overtank 10 through the manhole opening 22. The manhole opening 22 has cover means 24 which can be removed or opened as required to provide access to the interior of the overtank 10.

The tank 10 also includes a vent 26 and a spare nozzle 28, which in this example is capped. Vent 26 is of any suitable construction, and a suitable vent is selected depending on the use of overtank 10 and within the ordinary skill in the art.

The overload seat means 30 consists of a small tube made of steel or the like that passes through a hole in the tube plate 17 and is attached to the tube plate 17 by welding or other suitable means. The overflow seat means 30 are substantially parallel to the longitudinal axis of the overtank 10 and communicate the inlet zone 15 with the liquid zone 16. The over-seat means 30 forms the base of the over-element 18, which is held firmly to the seat means 30 by a retaining device 20. The overlay element 18 typically has a length of 50 inches (127 cm) to 80 inches (203.2 cm) and an outer diameter of 1 inch (2.54 cm) to 3 inches (7.62 cm).
inches) and typically has a length of 25.4 cm (10 inches)
It may consist of a single element or several cartridges, which are combined to form one element.

The over-element 18 according to the invention is shown in FIGS.
It is shown in detail in the figure. This element 18 includes a tubular support core 82 and a plurality of layers 84, 8 of strand material.
6. Tubular support core 82 is preferably made of stainless steel and includes a number of spaced holes in the outer surface of support core 82 to create an approximately 20 percent open area. The preferred range for the percent open area or pores of the support core is 5 percent to 65 percent, and the inner diameter of the support core 82 is preferably 19.05 mm (3/4 inch) and 34.9 mm.
(13/8 inches).

The innermost layer 84 and the outermost layer 86 may be made of yarns such as nylon, Orlon (trade name for acrylic fiber manufactured by DuPont), polypropylene, cotton, etc., as is known in the art. Core 8 supporting continuous strands of other strand materials
It is formed by winding it spirally around 2. The cross-section of the yarn or other strand material may be round, circular, triangular or the like as long as the particle retention capacity according to the invention is achieved. fact,
The cross-section of the yarn changes due to the contact of adjacent strands and the winding tension as the yarn is wound.

The spacing between adjacent strands of material is 1.58 (1/
16 inches) or less, creating an open area of less than 1 percent so that the protruding fibers or other irregularities on the surface of the yarn trap the particles, thereby creating a relatively strong bond between the particles and each yarn strand. increases the overall particle retention capacity. The particle retention capacity of each layer of yarn or other material depends on many factors in addition to spacing. For example, particle retention capacity can be varied by changing the tension with which the thread is wound, the thickness of each layer of thread, or by changing the pattern formed as the strand is wound back and forth. It can be changed by twisting it. The ability to retain particles can also be varied by the type of thread, the material of the thread and the manner in which the thread is handled. For example, nylon threads can be fluffed to create a rough surface;
Affects the particle retention capacity of the final over-cartridge.

The method of producing adequate particle retention capacity is not critical to the present invention, and most of the techniques described above are well known to those skilled in the art. However, it is essential that the over-element 18 be wrapped in such a way as to produce a variable capacity to retain particles as described herein and explained by the term "nominal particle retention number." The nominal particle retention number of the superelement layer is:
Particles in the form of Fine Arizona Air Dust in a water suspension at approximately 70°C (21°C) at a flow rate of 3.5 gallons per minute per square foot (0.14m ³ /m ² /min) is the maximum length of the smallest particle that can be removed by more than 90% by a layer of superelements when introduced at . Therefore, a higher nominal particle retention number means a larger size of the smallest particle that can be removed and therefore a coarser density of superelements. Conversely, a small nominal particle retention number means that the density of superelements is fine. For example, if the layer of the superelement has a nominal particle retention number of 25 microns and a large amount of Fine Arizona Air Dust is passed through the superelement in a water suspension as described above, then the largest dimension of 25 microns or more 90 percent or more of the particles having . The inlet concentration of Huain Arizona Air Dust was not critical and was tested at a concentration of 100 ± 25 milligrams per liter.

Fine Arizona Air Dust is a commercially available material utilized to make the type of measurements made in this text. This material is obtained from natural Arizona dust and is provided by General Motors' AC Spark Plug Division. The material has the following particle distribution:

Micron Range Percentage 0-5 39±2 5-10 18±3 10-20 16±3 20-40 18±3 40-80 9±3 Any other material with the same particle distribution can be employed according to the present invention You may do so.

In a preferred embodiment of the invention, there are at least two layers of strand material: an outermost layer 86 and an innermost layer 84. As used herein, the term "layer" refers to a wrap of strand material sufficient to produce the desired nominal particle retention number uniformly along the superelement. A "layer" thus includes many overlapping strands of material, depending on the particle wrapping pattern employed. Conversely, the upper layer is not visually distinct from the lower layer and has the same nominal particle retention number.

The number of passes of the winding unit along the support core and the growing lead position of the winding unit are determined by the desired particle retention capacity. outermost layer 86
The nominal particle retention number of is less than the nominal particle retention number of the innermost layer 84.

If the filter element 18 includes layers in addition to the innermost layer 84 and the outermost layer 86, each of these layers, in addition to the innermost layer, contains nominal particles smaller than the adjacent inner layer. It is desirable to have a retention number. In this method, the over-element 18 comprises a plurality of layers having a nominal particle retention number that decreases from the innermost layer 84 to the outermost layer 86.

Contains impurities in water from about 50 parts per 1 billion to 1 billion parts per billion.
It has been reduced to 10 copies, and 60 to 60 copies.
For use with overunits that have been precoated with a mixture of cation and anion exchange resins in the particle size range of 400 mesh, a preferred embodiment of the present invention has a nominal particle size between 1 micron and 25 microns. It includes an outermost layer 86 having a retention number and an innermost layer 84 having a nominal particle retention number between 25 and 100 microns. According to this preferred construction of the invention, overlay element 18 is a surface overlay, ie, overlay whose effective overdepth is limited to a "minimum depth" at or near the surface.

According to the invention, the innermost layer 84 of wrapped material
improves the backwash flow distribution by increasing the pressure drop between the beginning and end of the path that the backwash liquid must take before reaching the outermost layer 86. In other words, the pressure drop between the main chamber (e.g., support core 82) and a number of smaller communicating chambers (e.g., the gaps between strands 84) causes Flow equalization is enhanced. The narrow, tortuous path provided by these gaps creates these pressure drops and therefore the flow of backwash fluid reaching the outermost layer 86 is reduced over the length of the outermost layer 86. becomes more uniform along the line. Additionally, the innermost layer 84 increases the area of surface overfill that can be provided by the outermost layer 86 in a less expensive manner than increasing the diameter and increasing the amount of material deposited within the core 82. This increased area is
The over-element 18 has a main over-element near the relatively small diameter support core 82.
useful life until consumption. an outermost layer 86 having a smaller nominal particle retention number than the innermost layer 84;
The utilization of the over-element 18 according to the present invention having a
The layer of yarn material in the innermost layer 84 is the layer of yarn material in the outermost layer 8
This provides the advantage of trapping particles pushed into the 6. Accordingly, such "streaming" particles are normally trapped but do not significantly impair the flow rate of liquid through the overbody in the direction of the use cycle.

In operation of the apparatus shown in FIG. 1, a precoat medium, in this example an aqueous slurry of fine ion exchange resin particles ranging in size from about 60 to 400 mesh, is stored in a precoat tank 32. A slurry line 34, controlled by a slurry valve 36, connects the precoat tank and a slurry pump 38.
A transfer line 40 connects the pump 38 and the inlet line 12 of the overtank 10. A transfer valve 42 located in transfer line 40 adjacent pump 38 controls the flow of slurry or liquid from pump 38 .

The water to be treated enters the filtration device through a supply line 44 having an inflow control valve 46. Supply pipe line 4
4 is connected to the transfer line 40 between the transfer control valve 42 and the inlet line 12.

Outlet line 14 from overtank 10 is connected to use line 48 and precoat return line 50 at a T-junction 52 . The service line 48 is connected to a service unit, not shown, such as a steam generator or the like, and has a service valve 54. Precoat return line 50 is connected to precoat tank 32 and has a return valve 56 that controls the flow rate of liquid returned to precoat tank 32 .

Bridge line 58 with bridge valve 60
are precoat return pipe 50 and slurry pipe 3
Connect 4 to each other. Dray line 62 with valve 64 communicates with inlet line 12 .

During the pre-coat stage, a pre-coat layer of fine ion exchange resin particles with a particle size range of about 60 to 400 meshes is applied upstream of over-element 18, i.e., water is applied to over-element 1.
8. Adhere to the side where it is introduced. Similarly, an overstage cake forms upstream of the precoat layer.

In preparing the filter device for operation, the first step is to precoat the filter element 18. For precoating purposes, the overtank 10 is filled with water with low impurities, such as pure water or demineralized water. A slurry of precoat media and purified or demineralized water is provided in precoat tank 32, the precoat media being ion exchange resin particles ranging in size from about 60 to 400 mesh.

All valves are closed except slurry valve 36, transfer valve 42, return valve 56, and bridge valve 60 during the precoat stage. The precoat step is initiated by starting pump 38, which draws resin precoat slurry from precoat tank 32 through slurry line 34 and into pump 38. The slurry is forced by pump 38 through transfer line 40 and inlet line 12 into overtank 10 . The pressure of the incoming slurry is such that the pure water or demineralized water in the overtank 10 is passed through the overtank 18 through the overtank 10.
It is extruded through the liquid zone 16 and exits via the outlet line 14. Part of the pure water or desalinated water is returned to the return pipe 5.
0 to the precoat tank 32 and another portion enters the slurry line 54 through the bridge line 58.
supplied to

As this circulation continues, the precoat slurry contacts the upstream surface of the over-element. The fine resin particles of the precoat media are separated from the slurry and deposited as a precoat layer on the upstream surface of the over-element 18. The slurry is circulated through the filter device in this manner until the resin precoat layer is sufficiently deeply deposited on the upstream surface of the filter element. The pre-coat stage is
Finish by closing slurry valve 36 and return valve 56. The filtration device is thus ready for use in treating feed water. The thickness of the precoat layer is not critical, but the precoat layer is approximately
1.58mm (1/16 inch) to 50.8mm (2 inch),
Preferably about 3.17 mm (1/8 inch) to
25.4mm (1 inch), most preferably 3.17mm (1/8 inch)
Thicknesses range from 15.8 mm (5/8 inch) to 15.8 mm (5/8 inch).

Operation is initiated by opening use valve 54 and inlet valve 46. In this way, untreated water enters the filtration device through the supply line 44, the transfer line 40, the inlet line 12 and the filtration tank 1.
Flows into 0. The pressure of the incoming untreated water forces the untreated water to flow through the resin precoat layer, through element 18 and out through liquid zone 16 and out outlet line 14 . Once the flow of use is established, transfer valve 4
2 and bridge valve 60 are closed, pump 38
to stop.

As untreated water passes through the precoat layer, ion exchange reactions occur to remove dissolved impurities from the water. Additionally, undissolved impurities are removed from the raw water by passing the water through precoated filter element 18. As processing continues, an overcake consisting of undissolved impurities forms in the precoat layer. The purified or treated water flows through the liquid zone 16, the outlet line 14 and into the use line 48. The purified water is directed by service line 48 to a supply tank or suitable device.

Eventually, the resin becomes depleted or fatigued and must be regenerated. At this time, the inflow valve 46 and the use valve 54 are closed to stop the overcycle, that is, the use cycle. Next, the excess tank 10 is cleaned. To this end, the vent 26 and drain valve 64 are opened and water and purge gas, usually air, are passed underneath and into the interior of the filter element 18 to gradually clean the filter element 18 from top to bottom. The valve 66 of the air line 68 communicating with the outlet line 14 is opened to admit air into the interior of the over-element 18 . At the same time, valve 74 of backwash line 76
is opened to introduce water into the over-element 18. This allows air under pressure and backwash water to enter liquid zone 16 and flow upwardly into the interior of filter element 18 . Preferably, the air flow rate is in the range of about 1 to 2 cubic feet per minute per square foot of surface area of the over-element (about 0.3 to 0.6 cubic meters per minute per square meter) and the water flow rate is in the range of about 1 to 2 cubic feet per minute per square foot of surface area of the over-element. Approximately 0.5 gallons per minute (approximately 0.5 gallons per minute per square meter)
0.02 cubic meters). Adjust the drain valve 62 to slowly increase the water level, preferably at about
Lower at a speed of 25.4cm to 266.7cm (10 to 15 inches). Air and water entering the filter tank 10 therefore first pass over the top of the filter element 18 and remove the precoat layer therefrom.

Once the excess tank 10 has been drained, the drain valve 64 is closed and the tank begins to refill with liquid passing through the excess element 18 in reverse flow. When tank 10 is filled to a level approximately 6 inches above the top of over-element 18, valves 66 and 74 in air line 68 and backwash line 76 are closed, and valve 64 is opened to drain the backwash water. is removed from tank 10.

The drain valve 64 is closed, and the air conduit 68 and the valves 66 and 74 of the backwash conduit 76 are opened to backwash the excess element 18 again. A somewhat higher liquid flow rate, e.g., 1 to 2 gallons per minute per square foot of element (approximately 0.04 to 0.08 cubic meters per minute per square meter) is used during this stage. feet (approximately 0.45 cubic meters per minute per square meter).After filling the tank 10 to a level above the top of the excess element 18, the drain valve 64 is re-opened to allow the liquid level to rise between 25.4 cm and 266.7 cm per minute. Reduce speed and continue the flow of air and backwash liquid. Close the backwash valve 74 and continue draining for a short time with only air introduced until complete draining occurs. Once tank 10 is empty,
Close drain valve 64 and air valve 66. Open the backwash valve 74 and fill the tank three times; once the tank 10 is full, close the vent 26 and backwash line valve 74. Tank 10 is filled with water and overlay element 18 is now ready to apply a new precoat as previously described.

Although air has been described as the purge gas, other gases such as nitrogen and oxygen may also be used as the purge gas. However, generally speaking, air is the most economical since it is readily available in most plants. Similarly, liquids other than water may be used during the backwash cycle. Examples of such liquids are alcohol, carbon tetrachloride, detergent solutions and soap solutions. The liquid is about 100〓 to 200〓
(38°C to 93°C).

Representative solid cation exchange resin particles that can be used in the particular filtration process described herein are divinylbenzene-styrene copolymer types, acrylic types, sulfonated coal types, and phenolic types. These may be used, for example, in the sodium, hydrogen or ammonium form. Typical solid anion exchange resin particles that can be used are phenol formaldehyde types, divinylbenzene-styrene copolymer types, acrylic types, and epoxy types. Anionic resin particles may be used, for example, in hydroxide or chloride form. A suitable resin is Amberline IR by Rohm & Haas in the form of large beads.
-120 and Amberline LRA-400, also sold by Dow Chemical Company as Dowex HCR-S and
It is commercially available under the trade name Dowex SBR-P.
Fine resins are prepared by reducing the particle size of these known large bead resins to the desired particle size range. These resin particles are regenerated and cleaned before use.

Although the method has been described for a precoat layer of fine ion exchange precoat particles, as will be understood by those skilled in the art, if the precoat layer is treated or untreated diatomaceous earth, cellulose fibers, polyacrylonitrile fibers or any other precoat material. This method is equally applicable. Moreover, while the embodiments described herein are preferred, many modifications can be devised by those skilled in the art that do not depart from the true spirit and scope of the invention. The claims are intended to include all such modifications.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a typical overtank having replaceable cylindrical overelements embodying the present invention; FIG. 2 is partially cut away to show the wound layers of strand material and the central support core; FIG. FIG. 3 is a cross-sectional view of the over-element of FIG. 2 taken along line 2--2, showing the relationship between the wound layers of strand material and the central support core; . 18... Excess element, 82... Support core, 84...
...Innermost layer, 86...Outermost layer.

Claims (1)

[Claims] 1. A super-element adapted to be precoated with particles in the size range of 60 to 400 mesh, having a perforated tubular core and a nominal particle retention number between 25 and 100 microns; an inner layer of strand material wrapped around the
An over-element having a nominal particle retention number of between 1 and 25 microns and having an outer layer wrapped around said inner layer.