JP2012166122A - Cylindrical filter element and filtration device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical filter element having a large treatment flow rate and a long filter service life while maintaining filtration accuracy required for a fluid, and used for classification filtration of a high-concentration particle fluid or a high-viscosity particle fluid.SOLUTION: This cylindrical filter element 1 is used for the classification filtration of the high-concentration or high-viscosity fine particle fluid, is formed of filter materials 9, 10 made of synthetic resin fiber disposed in a nearly concentric circular state, and makes a flow direction of the fluid directed to the peripheral direction from a center part. The cylindrical filter element 1 is formed such that the filtration efficiency of the filter materials stepwise increases in at least two stages to a direction to which a diameter of the cylindrical filter element increases, and is configured such that classified particles can pass. A flux of the outermost filter material is increased to enhance the filtration service life.

Description

The present invention relates to a cylindrical filter element useful for classification filtration of a high-concentration particulate fluid or a high-viscosity particulate fluid, and a filtration apparatus including the filter element. Specifically, the filtration life is significantly improved as compared with the conventional one. The present invention relates to a cylindrical filter element and a filtration device including the filter element.

  Typical examples of high-concentration particle-containing fluids include ferromagnetic particle fluids for magnetic recording media, high dielectric particle fluids for ceramic capacitors, and positive electrode active material particle fluids and negative electrode active material particle fluids for secondary batteries. It is a fluid. These fluids are applied on a substrate to a thickness of several microns or more, and are formed into a film by binding particles through heat drying and the like. For this reason, the particle concentration of each fluid is approximately 10 wt% or more, and since the binder or dispersant such as a polymer is contained, the viscosity of the fluid is approximately 500 cP (0.1 Pa · sec) or more. . Also, depending on the type of polymer contained, in addition to the fluid flow characteristics exhibiting Newtonian fluid, those exhibiting pseudoplasticity in which the apparent viscosity decreases as the shear stress to the fluid increases, and appear as the shear stress increases. Some exhibit dilatants with increasing viscosity. If such fluid contains coarse particles produced in the pulverization step or coarse particles due to secondary aggregation, the quality of the film formed on the substrate is degraded, so classification filtration is performed for the purpose of removing coarse particles. Yes.

  Conventionally, a cylindrical filter element having a filter medium layer formed of a metal mesh, glass fiber, or synthetic resin fiber has been used for such high-concentration fluid or high-viscosity fluid classification filtration. The cylindrical filter element is housed in a metal housing or synthetic resin housing. When the filter element reaches its end of life due to clogging, etc., the filter element can be replaced by opening the housing for the metal housing. Or replace the entire synthetic resin housing. When the filter element is replaced, the film forming process is interrupted, and the fluid remaining in the filter element and the housing is discarded without being used. For this reason, it is required to remove particles having a coarse particle size required for such a cylindrical filter element, to have a large treatment flow rate and to have a long life. As the cylindrical element, one having an outer diameter of φ60-65 and a substantially constant size is used.

  FIG. 1 schematically shows an example of the structure of a filter medium of a conventional cylindrical filter element 1. FIG. 2 is a cross-sectional view taken along the line AA in FIG.

  The example shown in FIG. 1 forms a cylindrical element by winding polymer nonwoven fabrics 2 to 5 having four types of filtration efficiency on a core (porous tubular body) 6 a plurality of times in descending order of filtration efficiency. Is an example in which the end plate 7 is made of a synthetic resin and the other end is bonded to a top plate 8 having a fluid connection port by thermal bonding.

  The example shown in FIG. 1 uses a synthetic resin nonwoven fabric having four types of filtration efficiencies so that the filter medium layers having different filtration efficiencies are gradually increased in a concentric manner from the outer periphery of the cylindrical filter element toward the center. However, even in a cylindrical filter element formed by winding one type of nonwoven fabric, the filtration efficiency of each wound layer is continuously increased in the central direction by consolidation of the filter medium by the winding pressure. Can be formed.

  The filtration efficiency of the filter medium is the percentage of the ratio between the difference between the number of inflow particles and the number of outflow particles and the ratio of the number of inflow particles by measuring the number of particles with a specific particle size flowing into the filter medium and the number of particles with the same diameter flowing out from the filter medium. This is different from the filtration efficiency based on the total particle concentration of the inflowing fluid.

  In general, coarse particles are captured by a filter medium having a low filtration efficiency, and finer particles are captured by a filter medium having a higher filtration efficiency. For this reason, providing a gradient in filtration efficiency is due to the intention of extending the filter life by allowing coarser particles to be captured by a filter medium having a lower filtration efficiency and allowing the entire filter medium to capture particles. In particular, in the fluid to be filtered with a relatively large number of coarse particles, the filter medium area is larger toward the outer peripheral side of the cylindrical filter element, so that more particles can be captured and the filtration life is longer.

  However, in the conventional cylindrical filter element, a filter medium with high filtration efficiency is wound in order from the core toward the outer periphery, and the filter medium layer with higher filtration efficiency has a smaller filtration area and fluid flux. Since the (fluid flow rate per unit filter medium area) is high, the filtration differential pressure increases. For this reason, the filtration resistance of the cylindrical filter element has an increase factor due to the structure of the filter medium layer in addition to the filter resistance inherent to the filter medium, and there is a tendency that the filtration flow rate cannot be increased.

  In particular, when the fluid to be filtered is a slurry such as a high-viscosity / high-concentration particle-dispersed fluid, the conventional cylindrical filter element has a problem that a sufficient filtration flow rate and filtration life cannot be obtained. Further, the particle size distribution in the slurry generally shows a first peak necessary for the slurry and a second peak having a large particle diameter, and the coarse particles of the second peak are captured, and the first peak is necessary. It is desirable not to capture particles having a large particle size as much as possible. However, in the conventional cylindrical filter element, the trapped amount of particles having a required particle size increases in accordance with the trapped amount of coarse particles trapped by the filter medium having a low filtration efficiency, but the trapped voids of the particles remain sufficiently. Therefore, there was a problem that a sufficient filtration flow rate and filtration life could not be obtained.

  As a cylindrical filter element having a long lifetime, a cylindrical filter element has been proposed in which a filter medium layer is formed thick and more coarse particles are captured by the filter medium. Patent Document 1 proposes a cylindrical filter element in which a polymer meltblown fiber is combined with a support fiber and a filtration fiber and laminated in the radial direction on a perforated circular tube (hereinafter referred to as a core). Patent Document 1 refers to an example of a cylindrical filter element in which filtration fibers having a mean fiber diameter that decreases from the outer surface toward the center. Patent Document 2 proposes a cylindrical filter element in which first filtration portions and second filtration portions are alternately arranged concentrically in a radial direction.

  Unlike the pleated filter element in which the filter medium layer described in Patent Documents 1 and 2 is formed into a tubular shape by weaving the filter medium, the filter medium is formed in several layers adjacent to the ring. In many cases, a structure in which coarse particles are selectively captured over the entire thickness and a gradient of filtration efficiency is obtained in the thickness direction of the filter medium with respect to the particle diameter is employed. Further, with respect to the flow direction of the fluid to be filtered, the flow from the outer surface of the cylindrical filter element to the core direction is assumed, and a filtration efficiency gradient that increases from the outer surface having a large filtration area to the core direction having a small filtration area is obtained. By adopting the structure, the filter medium of the cylindrical filter element is prevented from being blocked and the filter life is increased.

  The filtration part or the filter medium layer having the highest filtration efficiency determines the minimum particle size of the trappable particles of the cylindrical filter element. For this reason, the filtration part with the highest filtration efficiency or the filtration part preceding the filter medium layer may be referred to as a pre-filtration part or a pre-filter medium.

  Patent Document 3 proposes a liquid purification apparatus in which a fluid flow direction of a cylindrical filter element using an activated carbon material as an adsorbing element is a side surface direction from a hollow center portion. The cylindrical filter element described in Patent Document 3 is a pressure-tight structure, and when a fluid is flowed from the side surface of the cylindrical filter element, the cylindrical filter element is compressed and deformed by the fluid pressure of the fluid, thereby reducing the filtration life. As a countermeasure.

  This is because the conventional cylindrical filter element provided with the filter medium layer was filtered from the outside to the inside, but it was thought that this would prevent the filtration life from being shortened due to clogging of the surface. . However, in the case of the classification filtration of the high concentration or high clay fine particle fluid of the present invention, the filtration life is extremely shortened in this way.

  When high-concentration particulate fluid or high-viscosity particulate fluid is classified and filtered with a cylindrical filter element, there is a trade-off relationship between the filtration accuracy required for the fluid, the processing flow rate and the filter life. In particular, there is a problem that the filter life is not sufficiently improved.

Patent No. 4049812 JP2010-253419 JP-A-9-206503

Of the present inventions, the invention described in claim 1 is for solving such problems, and maintains a high filtration accuracy required for a fluid while maintaining a high processing flow rate and a long filter life. An object of the present invention is to provide a cylindrical filter element used for classification filtration of particulate fluid or high-viscosity particulate fluid.

  In addition to the above object, an object of the present invention is to provide a cylindrical filter element that further enhances the filtration accuracy by preventing the filter medium from spreading due to the pressure of the fluid.

As a result of extensive research on the structure of the filter medium of the cylindrical filter element that filters a high-concentration particle fluid having a particle concentration of 10 wt% or more and a viscosity of 500 cP or more, the present inventor has ensured filtration accuracy and has a filtration flow rate The present inventors have found a structure of a cylindrical filter element that increases and has a long filtration life.

  That is, as a result of diligent research, the present inventor has arranged the flow direction of the fluid from the central part (core side) of the cylindrical filter element to the outer peripheral direction, and arranges a filter medium with high filtration efficiency at the outermost diameter part of the cylindrical filter element. The inventors have found that the filter differential pressure can be reduced by maximizing the filtration area of the filter medium having the highest filtration efficiency, and that a cylindrical filter element having a long filter life can be obtained. In particular, since the fluid flux of the cylindrical element is inversely proportional to the diameter of the cylindrical element, a high-viscosity fluid has a great effect of reducing the filtration differential pressure.

The present invention is a cylindrical filter that is used for classification filtration of high-concentration or high-clay fine particle fluid, is formed of a filter material made of synthetic resin fibers arranged substantially concentrically, and has a fluid flow direction from the central portion to the outer peripheral direction. The filter element is formed so that the filtration efficiency of the filter medium in the thickness direction of the filter medium increases stepwise in at least two stages with respect to the direction in which the diameter of the cylindrical filter element increases. It is preferable that the fine particle fluid is a fluid that can be filtered with a fine particle concentration of 10 wt% or more and clay of 500 cP or more.

  The synthetic resin fiber filter medium arranged substantially concentrically is a nonwoven fabric, and the average fiber diameter of the nonwoven fabric is in the thickness direction of the filter medium of the cylindrical filter element and the direction in which the diameter of the cylindrical filter element increases. It is preferable to form it so that it becomes smaller in steps of at least two steps.

  The two stages are composed of a first filtration part composed of a non-woven fabric arranged substantially concentrically and a non-woven fabric having an average fiber diameter smaller than that of the first filtration part arranged on the outer diameter part of the first filtration part It is preferable that the second filtering unit is constructed.

  The average fiber diameter of the nonwoven fabric constituting the first filtration part is 1.5 times to 3 times the average fiber diameter of the nonwoven fabric constituting the second filtration part, and the radial direction of the first filtration part is It is preferable that the thickness is not less than 1 and not more than 5 times the radial thickness of the second filtration part.

  It is preferable that the second filtration unit suppresses the expansion of the filter medium due to the pressure of the fluid by the support material.

  It is preferable that the second filtration part alternately arranges the support material and the nonwoven fabric constituting the second filtration part (Claim 7).

  It is preferable that the second filtration part alternately arranges a nonwoven fabric having an average fiber diameter equal to or larger than that of the nonwoven fabric constituting the first filtration part and a nonwoven fabric constituting the second filtration part (invention). Item 8). It is preferable that the synthetic resin fiber filter medium is disposed concentrically on the porous cylinder (claim 9).

  It is preferable that the fibrous polymer contains at least one of polypropylene, polyethylene, polyester, polyamide, and fluororesin (claim 10).

  The filtration device of the present invention is a filtration device in which the tubular filter element according to any one of claims 1 to 9 is installed in a filter housing, and the air vent pipe passes through an end plate of the tubular filter element. And the top plate of the tubular filter is connected to the inlet connection of the filter housing.

According to the present invention, a cylindrical filter element having a long filter life and a large processing flow rate can be provided, so that the cylindrical filter element can be reduced in size, and when the filter is replaced, the fluid remaining in the filter element and the housing is removed. There is an advantage that the amount of liquid discarded without being used can be reduced.

  It is thought that the cause of the effect of the present invention is that the flux of the filter medium having a high filtration efficiency in the outermost layer is increased.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 3 schematically shows an example of the structure of the filter medium of the cylindrical filter element 1 which is one embodiment of the present invention. FIG. 4 is a cross-sectional view taken along the line BB in FIG. FIG. 3 is an example of a cylindrical filter element formed by winding a synthetic resin nonwoven fabric on a core 6, and the nonwoven fabric is wound a plurality of times at a constant winding pressure to a predetermined diameter to form a first filtration unit 9. The second filtration unit 10 was formed on the first filtration unit 9 by wrapping a non-woven fabric smaller than the nonwoven fabric constituting the first filtration unit 9 and a net serving as a support material on the first filtration unit 9. Is. As with the conventional cylindrical filter element shown in FIG. 1, the cylindrical filter element is formed by thermally bonding one end to a synthetic resin end plate 7 and the other end to a top plate 8 having a fluid connection port. The

  The filtration efficiency of the filter medium depends on the average fiber diameter of the filter medium and the porosity of the filter medium. When a tubular filter element is formed by winding a nonwoven fabric, the compressive force generated by the winding becomes higher as the layer is closer to the center, and the porosity of the nonwoven fabric is lowered and the filtration efficiency is increased. For this reason, when the same nonwoven fabric is wound to form a cylindrical filter element, the gradient of the filtration efficiency is increased in the direction of the center of the cylindrical filter element due to the consolidation of the nonwoven fabric. However, since the rate of increase in consolidation of the nonwoven fabric decreases as the average fiber diameter increases, the nonwoven fabric is wound several times on the core in the order of increasing average fiber diameter. The gradient can be formed so as to increase in the direction in which the diameter of the cylindrical filter element increases.

  If a nonwoven fabric with multiple average fiber diameters is formed by winding the core multiple times in order of increasing average fiber diameter, the filtration efficiency can be changed in stages, which is effective for filtering a fluid with a broad particle size distribution. Is. In addition, when filtering a slurry having two peaks as described above, a cylindrical filter element having a two-stage filtration efficiency using two types of non-woven fabric is used to form a filtration layer having a high filtration efficiency. The effect of arranging the outer diameter portion of the element is high.

  In particular, the average fiber diameter of the nonwoven fabric constituting the first filtration portion 9 located on the core side of the cylindrical filter element is the nonwoven fabric constituting the second filtration portion 10 located on the outer peripheral side of the first filtration portion 9. The average fiber diameter is 1.5 to 3 times, and the radial thickness of the cylindrical element of the first filtration unit 9 is 1 to 5 times the radial thickness of the second filtration unit 10 A cylindrical filter element characterized by the above is preferred.

  The second filtration unit 10 selects a filter medium having a filtration efficiency that allows particles having a particle size of the first peak in the slurry to pass through and traps a particle size that is not permitted as a slurry. For example, when the second filtration unit 10 is configured with a filter medium having a particle size with filtration efficiency of 80% (hereinafter referred to as filtration accuracy of the filter medium) close to the particle diameter of the first peak, the shape of the particle size distribution of the slurry However, except for special cases, the filtration accuracy of the filter medium of the first filtration unit 9 may be at most several times the filtration accuracy of the second filtration unit 10.

  If the filtration accuracy of the filter medium of the first filter unit 9 is too high, the filter medium of the first filter unit 9 cannot sufficiently capture the coarse particles in the slurry, and the second filter unit 10 is blocked by the coarse particles. Conversely, if the filtration accuracy of the filter medium of the first filtration unit 9 is too close to the filtration accuracy of the second filtration unit 10, the first filtration unit 9 is blocked and the filter life is shortened.

  For this reason, when setting the ratio of the average fiber diameter of the first filtration part 9 to the average fiber diameter of the second filtration part 10 (hereinafter referred to as the ratio of the average fiber diameter) to be small, the thickness of the first filtration part 9 If the average fiber diameter ratio is large, the thickness of the first filtration part 9 is increased, but if the average fiber diameter ratio exceeds 3, the filtration accuracy is too far away and the second filtration part If the ratio of the thickness of the first filtration part 9 to the thickness of 10 exceeds 5, the outer diameter of the cylindrical filter element is almost constant, so the thickness of the second filtration part 10 becomes too small Stable filtration accuracy cannot be maintained.

  The second filtration unit 10 is made of a composite material having a large average fiber diameter equal to or greater than that of the net material or the nonwoven fabric constituting the first filtration unit 9 as a support material. can get. This is because the nonwoven fabric constituting the second filtration unit 10 receives tensile stress from the filtration fluid and prevents a reduction in filtration efficiency due to the elongation of the nonwoven fabric. The support material having high rigidity and the nonwoven fabric constituting the second filtration unit 10 are alternately arranged to suppress the elongation of the nonwoven fabric. In particular, the first filtration unit 9 is configured as a support material. When a non-woven fabric is used, the number of constituent filter media can be reduced, which is economical.

  As the material of the filter medium constituting the cylindrical filter element, inorganic fibers such as glass fiber and carbon fiber can be used, but polyolefins such as polypropylene and polyethylene, thermoplastic polyamide, polyester, polyethersulfone, acrylic, polystyrene, fluororesin A polymer nonwoven fabric such as a thermoplastic polyurethane resin can be used.

  FIG. 5 is a schematic cross-sectional view illustrating the structure of a filter module 11 in which the cylindrical filter element 1 of the present invention is housed in a synthetic resin housing. The housing made of synthetic resin is composed of a shell cap 11a having a fluid inlet connection portion 12 and an outlet connection portion 13, and a shell 11b having an air vent connection portion 14, and a top plate 8 having a fluid connection port of the cylindrical filter element 1. And the inlet connection portion 12 are coaxially and liquid-tightly connected, and the shell cap 9a and the shell 9b are bonded.

  Since the flow direction of the fluid is from the center of the cylindrical filter element to the outer peripheral direction, a space 15 into which the fluid to be filtered flows is formed inside the core, and the fluid to be filtered is filtered by the pressure from the inlet connection portion 12. The fluid flows from the center of the element 1 toward the outer surface via the core and is output from the outlet connection 13. Air bubbles contained in the fluid to be filtered and air remaining in the space 15 are appropriately discharged from the air vent connection part 14 through the pipe 16 installed through the end plate 7 to contain air bubbles in the filtered fluid. To prevent.

The following examples further illustrate the present invention.
(Adjustment of filtration accuracy measurement solution)
A measurement liquid having a particle concentration of 10 ppm was prepared by dispersing alumina powder (800 mesh pass) in pure water.

(Measurement of filtration accuracy)
The measurement liquid is filtered at a constant flow rate of 2.5 liters / min using a cylindrical filter element with a total length of 62.5 mm, and the particle size distribution of the measurement liquid (liquid before filtration) and the liquid after filtration are measured by a laser scattering type particle counter. Measured with Using the particle count value for each particle size, (N ₀ −N ₁ ) x100 / N ₀
The filtration efficiency indicated by is calculated, and the particle size at which the filtration efficiency is 80% is defined as the filtration accuracy. Here, N ₀ is the particle count value of the specific particle size of the liquid before filtration, and N ₁ is the particle count value of the specific particle size of the liquid after filtration.

(Adjustment of test slurry 1)
Dissolve carboxymethyl cellulose (CMC) in pure water, add organic particles having a peak at 12 um and a dispersant, stir well, particle concentration 10 wt%, fluid viscosity 733 cP (B type viscometer, rotor rotation speed 12 rpm Measured value).

(Adjustment of test slurry 2)

Carboxymethylcellulose (CMC) is dissolved in pure water, organic particles having a peak at 12 um and a dispersant are added and sufficiently stirred, particle concentration 40 wt%, fluid viscosity 5051 cP (B type viscometer, rotor rotation speed 12 rpm Measured value).

(Slurry filtration test)
A cylindrical filter element with a total length of 62.5mm is built in a synthetic resin housing, and the pressure at the connecting pipe connected to the fluid inlet connection is adjusted to 100 kPa to perform constant pressure filtration. The liquid was introduced into a weigh scale and the change with time of the weight was recorded. Using the change in weight over time, the total flow rate when the flow rate was reduced to 20% of the initial flow rate (g / min) and the initial flow rate was calculated as the throughput.

As a first filtration part, a polypropylene nonwoven fabric with an average fiber diameter of 40 um is wound around a core part with a diameter of 36 mm with a constant winding pressure up to a diameter of 52 mm, and further an average fiber as a second filtration part above the first filtration part A cylindrical filter element having a total length of 62.5 mm wound up to a diameter of 62 mm is produced by alternately arranging a polypropylene nonwoven fabric having a diameter of 20 μm and a polypropylene nonwoven fabric having an average fiber diameter of 40 μm, so that the filter module structure shown in FIG. A module was manufactured in a polypropylene filter housing, and the flow direction of fluid was from the center of the element to the outer peripheral direction. The thickness of the first filtration part is 8 mm, and the thickness of the second filtration part is 5 mm.

As a first filtration part, a polypropylene nonwoven fabric with an average fiber diameter of 40 um is wound around a core part with a diameter of 36 mm with a constant winding pressure up to a diameter of 56 mm, and further, as an upper layer second filtration part of the first filtration part, an average fiber diameter A cylindrical filter element with a total length of 62.5mm, which is a 20um polypropylene non-woven fabric wound to a diameter of 62mm, is manufactured, and is installed in a polypropylene filter housing so that the filter module structure 11 shown in Fig. 6 is achieved. A module having an outer peripheral direction from the center of the element was manufactured. The thickness of the first filtration part is 10 mm, and the thickness of the second filtration part is 3 mm.
(Comparative Example 1)

A tubular filter element with a total length of 62.5 mm is produced by winding a polypropylene nonwoven fabric with an average fiber diameter of 40 um around a core of 36 mm diameter with a constant winding pressure up to a diameter of 54 mm so that the structure 11 of the filter module shown in FIG. 6 is obtained. Then, a module was manufactured in a polypropylene filter housing, and the flow direction of fluid was from the center of the element to the outer peripheral direction.
(Comparative Example 2)

The cylindrical filter element described in Comparative Example 1 is mounted in a polypropylene filter housing so as to have the filter module structure 17 shown in FIG. 7, and the flow direction of the fluid is from the outer periphery of the cylindrical filter element to the central direction. A conventional filter module was manufactured.
(Comparative Example 3)

A filtration unit consisting of polypropylene nonwoven fabric with an average fiber diameter of 20um and polypropylene nonwoven fabric with an average fiber diameter of 40um is wound around a core of 36mm with a constant winding pressure up to a diameter of 42mm. A cylindrical filter element with a total length of 62.5 mm wound to a diameter of 62 mm is manufactured, and is installed in a polypropylene filter housing so as to have the filter module structure 11 shown in FIG. 6, and the fluid flow direction is the center of the element. A module with an outer peripheral direction was manufactured.
(Comparative Example 4)

The cylindrical filter element described in Comparative Example 3 is mounted in a polypropylene filter housing so as to have the filter module structure 17 shown in FIG. 7, and the flow direction of the fluid is from the outer periphery of the cylindrical filter element to the central direction. A conventional filter module was manufactured.
The structure of the cylindrical filter element of each Example and Comparative Example and the fluid flow direction are shown together in FIG.
(Test results)
Table 1 shows the measurement results of the filtration accuracy of the filter modules of Examples 1 and 2 and Comparative Examples 1 to 4, and the measurement results of the initial flow rate and the processing amount when the experimental slurries 1 and 2 are fluids to be filtered. .

実施例1、2の濾過精度は、実験用スラリーの粒度分布のピーク値を示す粒径の粒子を捕捉しない程度の濾過効率を有する濾材が選定され、10ppmの粒子濃度での濾過精度が実施例1では17um、実施例2では18umであった。比較例3、4は、実施例1の第2の濾過部に使用された濾材をコア近傍に設置した筒形フィルターエレメントの例であり、濾過精度は共に17umであった。また、比較例1、2は、実施例1、2の第1の濾過部に使用された濾材及び濾材厚さ(外径54mm)で構成した筒形フィルターエレメントの例で、濾過精度は共に25umで、流体の流れ方向には依存しなかった。

The filtration accuracy of Examples 1 and 2 is selected as a filter medium having a filtration efficiency that does not capture particles having a particle size showing the peak value of the particle size distribution of the experimental slurry, and the filtration accuracy at a particle concentration of 10 ppm is an example. It was 17 um in 1 and 18 um in Example 2. Comparative Examples 3 and 4 are examples of cylindrical filter elements in which the filter medium used in the second filtration part of Example 1 was installed near the core, and the filtration accuracy was 17 um. Comparative Examples 1 and 2 are examples of a cylindrical filter element constituted by the filter medium used in the first filtration part of Examples 1 and 2 and the filter medium thickness (outer diameter 54 mm), both of which have a filtration accuracy of 25 μm. It did not depend on the direction of fluid flow.

  Comparing the filtration accuracy of Example 1 and Example 2, Example 1 was 1 um smaller, but it can be determined that this is the effect of suppressing the elongation of the filter medium by the support material.

  When comparing the slurry filtration test results of Example 1 and Comparative Example 4, the initial flow rate of Example 1 is about twice that of Comparative Example 4 for both Test Slurry 1 and Test Slurry, and the processing amount is about 5 times as great. Excellent results were obtained. Comparative Example 4 is a conventional cylindrical filter element in which the flow direction of the fluid is from the outer periphery of the cylindrical element to the central direction, and the filter medium layers having different filtration efficiencies are formed in two steps from the outer periphery to the central direction. is there. This shows that the effect of the filter medium structure in which the flow direction of the fluid, which is one form of the present invention, is changed from the center to the outer periphery and the filter medium layers having different filtration efficiencies are arranged in two steps from the center to the outer periphery is extremely large.

  Comparing the slurry filtration test results of Comparative Examples 1 and 2, in the cylindrical filter element of the same filter medium configuration, the initial flow rate is affected by the fluid flow direction, and in Comparative Example 1, that is, the fluid flow direction is changed from the center of the element to the outer periphery. When the direction was set, the result was about 1.2 times larger than that of Comparative Example 2, but the processing amount was smaller than that of Comparative Example 2. Comparative Example 1 is for evaluating the performance as the pre-filtration unit of the second filtration unit of Examples 1 and 2, and Comparative Example 2 is for evaluating the performance as the pre-filtration unit of Comparative Example 4, Comparative Example 1 However, it can be determined that the amount of treatment is smaller than that of Comparative Example 2 to capture coarse particles earlier and reduce the burden of capturing coarse particles in a filtration unit with high filtration accuracy. It can be said that Example 1 is one of the causes that the processing amount is much larger than that of Comparative Example 4.

  When the filtration test results of Examples 1 and 2 were compared for Test Slurry 1 and Test Slurry 2, the initial flow rate showed a decrease in flow rate that was approximately inversely proportional to the viscosity of the slurry. Regarding the change in the processing amount, even when the particle concentration of the slurry was increased from 10 wt% to 40 wt%, no significant decrease was observed, and excellent filtration life characteristics were exhibited even for a high particle concentration fluid.

  Example 1 and Example 2 use a non-woven fabric for two types of average fiber diameters, and the tube formed so that the filtration efficiency of the filtration part is gradually reduced in two steps with respect to the direction in which the element diameter increases. This is an example of a filter element, and the test results relate to a slurry in which particles having a single peak in a particle size distribution of 12 μm are dispersed, but the effect of the structure of the present invention is compared to a slurry of other particle size distribution. Is also effective.

It is a schematic cross section of the conventional cylindrical filter element. It is AA sectional drawing of FIG. It is a schematic cross section which shows one Example of the cylindrical filter element of this invention. It is BB sectional drawing of FIG. It is a schematic cross section of the filter module equipped with the cylindrical filter element of the present invention. It is a schematic cross section which shows the structure of the filter module of this invention for a filtration test. It is a schematic cross section which shows the structure of the filter module for filtration tests. It is explanatory drawing of the filter medium structure of an Example and a comparative example, and the flow direction of a fluid.

1 ... Filter element 6 ... Core (porous tube)
7 ··· End plate 8 ··· Top plate 9 ··· First filter portion 10 ··· Second filter portion 11 ··· Filter Module 12 ··· Fluid inlet connection 16 ··· Air bleeding pipe

Claims (11)

A cylindrical filter element that is used for classification filtration of high-concentration or high-clay fine particle fluid, is formed of a filter material made of synthetic resin fibers arranged approximately concentrically, and the fluid flow direction is from the center to the outer periphery. The filter medium is formed so that the filtration efficiency of the filter medium in the thickness direction of the filter medium increases stepwise in at least two stages with respect to the direction in which the diameter of the cylindrical filter element increases, so that the classified particles can pass through. A cylindrical filter element characterized by comprising 2. The cylindrical filter element according to claim 1, wherein the particulate fluid is a fluid having a particulate concentration of 10 wt% or more and clay of 500 cP or more and capable of being filtered. The synthetic resin fiber filter medium arranged substantially concentrically is a nonwoven fabric, and the average fiber diameter of the nonwoven fabric is in the thickness direction of the filter medium of the cylindrical filter element and the direction in which the diameter of the cylindrical filter element increases. The cylindrical filter element according to claim 2, wherein the cylindrical filter element is formed so as to be gradually reduced to at least two stages. The two stages are composed of a first filtration part composed of a non-woven fabric arranged substantially concentrically and a non-woven fabric having an average fiber diameter smaller than that of the first filtration part arranged on the outer diameter part of the first filtration part The cylindrical filter element of Claim 3 comprised from the made 2nd filtration part. The average fiber diameter of the nonwoven fabric constituting the first filtration part is 1.5 times to 3 times the average fiber diameter of the nonwoven fabric constituting the second filtration part, and the radial direction of the first filtration part is The cylindrical filter element according to claim 4 whose thickness is 1 to 5 times the thickness of the diameter direction of the 2nd filtration part. The cylindrical filter element according to any one of claims 1 to 5, wherein the second filtration unit suppresses expansion of the filter medium due to fluid pressure by a support material. The cylindrical filter element according to claim 6, wherein the second filtration part alternately arranges a support material and a nonwoven fabric constituting the second filtration part. The said 2nd filtration part has arrange | positioned the nonwoven fabric which has the average fiber diameter equivalent to or more than the nonwoven fabric which comprises a 1st filtration part, and the nonwoven fabric which comprises a 2nd filtration part alternately. Cylindrical filter element. The cylindrical filter element according to claim 1, wherein the filter material of the synthetic resin fiber is disposed concentrically on a porous cylinder. The cylindrical filter element according to claim 1, wherein the fibrous polymer contains at least one of polypropylene, polyethylene, polyester, polyamide, and fluororesin. In the filter apparatus which equipped the cylindrical filter element in any one of Claims 1-9 in the filter housing, the air vent pipe penetrates the end plate of this cylindrical filter element, and this cylindrical shape The filter top plate is connected to the inlet connection portion of the filter housing.

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