METHOD TO FORM A DUST COLLECTING LAYER ON A POROUS BODY WITHOUT USING A BINDER

Abstract

The present invention provides a method for producing a filter element that does not have any peeling of fine particles constituting a dust collection layer, and maintains high performance for long periods of time even when scaled up. The method includes depositing to form a layer of fine particles including low melting fine particles and small diameter fine particles, on a surface of a filter element material while suctioning the filter element material, and heating the layer of the fine particles by using a heater such as an infrared heater or an oven to sinter the fine particles to form the dust collection layer.

Claims

1. A method for producing a filter element, comprising: mixing two or more kinds of fine particles sufficiently; forming a layer made of the two or more kinds of fine particles on a surface of a filter element material; heating by using a heater to melt one or more kinds of fine particles of the fine particles; and forming a dust collection layer after cooling; wherein a softening point of one or more kinds of fine particles of the two or more kinds of fine particles is lower than a softening point of other fine particles and particles constituting the filter element material.

2. The method for producing a filter element according to claim 1, wherein a particle diameter of one or more kinds of fine particles of the two or more kinds of fine particles is/are smaller than a particle diameter of resin constituting the filter element material.

3. The method for producing a filter element according to claim 1, wherein the two or more kinds of fine particles are sufficiently mixed in advance and then sucked onto the filter element material to form the filter element on a surface of the filter element material.

4. The method for producing a filter element according to claim 1, wherein the two or more kinds of fine particles are separately sucked onto the filter element material to form the filter element in a layered form on a surface of the filter element material.

5. The method for producing a filter element according to claim 1, wherein in the heating the heater comprises an infrared heater or oven.

6. The method for producing a filter element according to claim 1, wherein the filter element comprises at least one pocket-like or bag-like structure; the at least one pocket-like or bag-like structure has an internal space enclosed by at least one wall of the filter element, leaving at least one clean fluid outlet opening; and the filter element has an inner surface facing the internal space) and an outer surface oriented in an opposite direction to the internal space, and a dust collection layer is formed on the outer surface of the filter element.

7. The method for producing a filter element according to claim 1, wherein the filter element comprises at least one pocket-like or bag-like structure; the at least one pocket-like or bag-like structure has an internal space enclosed by at least one wall of the filter element, leaving at least one unprocessed fluid inlet opening; the filter element has an inner surface facing the internal space and an outer surface facing in an opposite direction to the internal space; and a dust collection layer is formed on the inner surface of the filter element.

8. The method for producing a filter element according to claim 1, wherein the filter element is formed with at least one filter element wall defining a lamellar structure; and the lamellar structure comprises a geometric configuration having a convex portion and a concave portion on at least one of two opposite sides of the at least one filter element wall.

9. The method for producing a filter element according to claim 8, wherein the geometric configuration comprises a plurality of convex portions and concave portions on both sides of the at least one filter element wall.

10. The method for producing a filter element according to claim 8, wherein the convex portion and the concave portion of the at least one filter element wall are shaped to form at least one undercut portion of the geometric configuration.

11. The method for producing a filter element according to claim 8, wherein the geometric configuration of the lamellar structure comprises a helical structure.

12. The method for producing a filter element according to claim 8, wherein the filter element is formed with at least one pocket-like or bag-like structure having a cylindrical, conical, or other rotational symmetric shape defined by the at least one filter element wall; and the convex portion and the concave portion of the at least one filter element wall are shaped to form the geometric configuration of the lamellar structure.

13. The method for producing a filter element according to claim 1, wherein one of the two or more kinds of fine particles constitutes a matrix material of the dust collection layer and is made of a same resin material as the filter element material.

14. The method for producing a filter element according to claim 13, wherein one of two kinds of fine particles constituting the matrix material of the dust collection layer comprises polyethylene.

15. The method for producing a filter element according to claim 1, wherein the dust collection layer is formed without using any binder or solvents.

16. The method for producing a filter element according to claim 1, wherein the two or more kinds of fine particles do not include perfluoroalkoxy alkane (PFA).

17. A filter element produced by using the method according to claim 1.

18. The method for producing a filter element according to claim 1, wherein the two or more kinds of fine particles are dry particles.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0119] FIG. 1 (1) is an external view of a general dust collector.

[0120] FIG. 1 (2) is an external view of a filter element (sintered-lamellar).

[0121] FIG. 1 (3) is a perspective view of a P-P cross section.

[0122] FIG. 2 is a heating means (oven).

[0123] FIG. 3 is a cross-sectional view of a jig for suction of a filter element material.

[0124] FIG. 4 is a photograph of a material of a 2-core element.

[0125] FIG. 5 is a cross-sectional image of an example.

[0126] FIG. 6 is a laboratory load testing device for a 2-core element.

[0127] FIG. 7 is a load testing device for a filter element in actual production size.

[0128] FIG. 8 is a graph illustrating the change in pressure loss of a filter element over time in actual production size, together with experimental results for conventional examples.

[0129] FIG. 9 shows a schematic view of a processing box body configured to form a dust collection layer on an outside of a pocket-shaped or bag-shaped filter element material, according to a further embodiment.

[0130] FIG. 10 shows a schematic cross-sectional view of a filter element produced by using the processing box body shown in FIG. 9.

[0131] FIG. 11 shows a schematic cross-sectional view of a processing box body configured to form a dust collection layer on an inside of a pocket-shaped or bag-shaped filter element material, according to a further embodiment.

[0132] FIG. 12 shows a schematic cross-sectional view of a filter element produced by using the processing box body shown in FIG. 11.

[0133] FIG. 13 shows a schematic view of a processing box body configured to form a dust collection layer on an inside of a pocket shaped or bag-shaped filter element material, according to a further embodiment.

[0134] FIG. 14 shows a different view of a filter element material in which a dust collection layer can be formed on an inside or outside of the filter element material, according to any one of embodiments of the present invention.

[0135] FIG. 15 shows a different view of a further filter element material in which a dust collection layer can be formed on an inside or outside of the filter element material, according to any one of embodiments of the present invention.

[0136] FIG. 16 shows a graph illustrating the change in pressure loss of the filter element over time in Example 9.

DESCRIPTION OF EMBODIMENTS

[0137] Hereinafter, the present invention will be described in detail based on examples of the present invention. However, the present invention is not limited to the following examples.

[0138] Moreover, a filter element used in the examples and comparative examples of the present invention includes a 2-core integrated element. The 2-core integrated element is a filter element for a scale-up testing having a structure with two sets of hollow chambers inside the filter element. The 2-core integrated element is obtained by forming a dust collection layer according to the present invention on an element material obtained by integrally sintering.

Example 1

[0139] A material of a 2-core element was placed in a jig for suction in FIG. 3. Mixed particles of 5 g were placed at the bottom of the jig, with a weight ratio of LLDPE (linear low molecular weight PE, D50=45 m): HDPE (high density PE, D50=10 m): PTFE (D50=3.7 m)=5:4:1. A ring blower disposed in communication with the jig through a pipe was used to blow compressed air from the compressed air blowoff port 92 at the bottom of the jig while suctioning at a filtration air velocity of 2.0 m/min. The mixed particles were then blown up, allowing them to sufficiently spread out over pores on the surface of the filter element material.

[0140] A gear oven (ACR45A, manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used to perform the heating and fusion bonding at an ambient temperature of 130 C. for 30 min to produce a 2-core filter element (filtration area 0.16 m.sup.2) with a dust collection layer.

[0141] The 2-core element obtained above was secured to a laboratory dust collection load testing device for the 2-core element (FIG. 6, manufactured by Nittetsu Mining Co., Ltd.). As an experimental dust collection powder, calcium carbonate powder for flue gas desulfurization (average particle diameter: 12 m, manufactured by Nittetsu Mining Co., Ltd.) was used to perform a dust collection load confirmation test for 5 minutes under a filtration air velocity of 1 m/min (processing air volume of 0.16 m.sup.3/min), and a dust feed concentration of (10 g/m.sup.3). In the dust collection load confirmation test, the pressure loss (kPa) and dust-containing concentration in exhaust air (LD-3K2, manufactured by SIBATA SCIENTIFIC TECHNOLOGY LTD.) at the start and end of the test were evaluated.

[0142] The obtained results are shown in the table together with an result of a similar experiment using a filter element made of a classification product (D50=24 m) of low molecular weight polyethylene powder (manufactured by Mitsui Fine Chemicals, Inc., Hi-WAX HP10A) used in Example 8 in Patent Literature 3.

[0143] Although the pressure loss of the filter element in the Example 1 was slightly higher than that in Patent Literature 3 (Example 8), the dust-containing concentration in exhaust air was significantly lower than that in Patent Literature 3 (Example 8).

Example 2

[0144] The filter element in actual production size produced above was secured to a load test device for a filter element in actual production size (FIG. 7: manufactured by Nittetsu Mining Co., Ltd.), and a dust collection load confirmation test was conducted. The structure of the load test device for a filter element in actual production size is the same as the general dust collector in FIG. 1, with the inside of the sealed casing divided into an upper clean air chamber 103 and a lower dust collection chamber 107 by an upper top plate 108 that is a partition wall.

[0145] Calcium carbonate powder for flue gas desulfurization (average particle diameter: 12 m, manufactured by Nittetsu Mining Co., Ltd.) was used for the experimental dust collection powder. The experimental dust collection powder was extracted by a quantitative supply device 101 installed downstream of an upper tank 102 to achieve the predetermined dust content. The experimental dust powder became dust-containing air in the pipe to flow into the dust collection chamber under the conditions of a filtration air velocity of 1 m/min (processing air volume of 18 m.sup.3/min) and a dust feed concentration of 5 g/m.sup.3. The dust-containing air was separated into dust and air by a testing filter element 106, which was secured in the dust collection chamber at a specified interval and numbers.

[0146] The dust collected by adhering to and depositing in the dust collection layer formed on the surface of the filter element material was discharged to a hopper 109 below the dust collection chamber at one-minute intervals by backwashing pulse air at 0.5 MPa, and stored in a lower tank 105 by using a dust conveyance device 104. The experimental dust powder stored in the lower tank was conveyed to the upper tank by an air transport device (not shown).

[0147] In the dust collection load confirmation test, the pressure loss (kPa) and the dust-containing concentration in exhaust air (LD-3K2, manufactured by SIBATA SCIENTIFIC TECHNOLOGY LTD.) at the start and end of the test were evaluated.

[0148] The test results are shown in FIG. 8.

[0149] From the graph in FIG. 8, it was found that the initial pressure loss of the filter element produced in Example 2 was slightly higher than that in Patent Literature 3 (Example 8); however, this quickly reversed, and the pressure loss of the filter element in Example 2 remained significantly lower as compared with the dust collection layer produced by the conventional technology.

[0150] This can be considered as follows. Under the conditions in Patent Literature 3 (Example 8), low-molecular-weight PE fine particles was melted, and the large-diameter particles that approximately left undissolved acted the formation of the pores of the dust collection layer. On the other hand, the dust collection layer produced in Example 2 is formed by a mixture of three kinds of fine particles, two of which is a mixture of fine particles that do not melt at the heating temperature, as well as the fine particles that do not melt by heating contribute to the formation of extremely fine pores. Thus, it is considered to be due to the formation of the dust collection layer that has fewer large pores causing blockages, although it has the high initial pressure loss.

Example 3

[0151] A material of a 2-core element was installed in the jig for suction in FIG. 3. Powders of LLDPE, HDPE, and PTFE were each placed separately at the bottom of the jig, and the ring blower disposed in communication with the jig through the pipe was used to blow compressed air from the compressed air blowoff port 92 at the bottom of the jig while suctioning at a filtration air velocity of 2.0 m/min. The mixed particles were then blown up, allowing them to sufficiently spread out over the pores on the surface of the filter element material. Specifically, the particles were each adhered to the surface of the element material in the following order: HDPE (D50=120 m), LLDPE (D50=20 m), HDPE (D50=10 m), LLDPE (D50=20 m), and PTFE (D50=3.7 m). After removing them from the jig, the gear oven (ACR45A, manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used to perform the heating and fusion bonding at an ambient temperature of 130 C. for 30 minutes to produce the 2-core element with the dust collection layer.

[0152] The 2-core element obtained above was secured to the laboratory dust collection load testing device for the 2-core element (FIG. 6, manufactured by Nittetsu Mining Co., Ltd.). Calcium carbonate powder for flue gas desulfurization (average particle diameter: 12 m, manufactured by Nittetsu Mining Co., Ltd.) was used for an experimental dust collection powder to perform a dust collection load confirmation test for 5 minutes under the conditions of a filtration air velocity of 1 m/min (processing air volume of 0.16 m.sup.3/min) and a dust feed concentration of 10 g/m.sup.3. In the dust collection load confirmation test, the pressure loss (kPa) and the dust-containing concentration in the exhaust air (LD-3K2, Shibata Scientific Instruments) at the start and end of the test were evaluated.

[0153] As is clear from the results shown in the table, in Example 3, it was possible to achieve a lower pressure loss while maintaining the collection performance in Example 1.

Table 1

TABLE-US-00001 TABLE Exhaust dust concentration Pressure loss [kPa] [g/m.sup.3] Test start End of test Test start End of test Patent Document 3 0.20 0.25 67 34 Example 1 0.29 0.36 28 4 Example 3 0.25 0.30 15 5

Example 4

[0154] FIG. 9 shows a schematic view of a processing box body 200 configured to form a dust collection layer 202 on an outside of a pocket-like filter element material 206, according to a further example.

[0155] The processing box body 200 has a processing box body housing 214 that completely encloses a processing space 222.

[0156] The processing box body housing 214 has an inlet opening 218 through which an aerosol including a carrier fluid and a powder mixture (i.e., a mixture of two or more kinds of fine particles dispersed in the carrier fluid) can enter the processing space 222 (see arrow A).

[0157] The processing box body housing 214 further has a mounting hole 216 configured to insert and mount a mounting flange 220.

[0158] The filter element material 206 of a filter element 204 including the dust collection layer 202 is fitted to the mounting flange 220.

[0159] In FIG. 9, the processing box body housing 214 is drawn in a partially cut-out configuration to better show the processing space 222 including the mounting flange 220 and the filter element material 206.

[0160] The filter element material 206, and thus the filter element 204 is also formed with at least one pocket-like or bag-like structure 310 having a pocket or bag shape (see FIGS. 14 and 15).

[0161] The pocket-like or bag-like structure 310 defines an internal space 208 of the filter element material 206 or the filter element 204.

[0162] The internal space 208 is enclosed by at least one filter element wall 210 (see FIG. 10).

[0163] At least one filter element wall 210 completely encloses the internal space 208, except for at least one clean fluid outlet opening 212.

[0164] Therefore, the filter element 204 has an inner surface facing the internal space 208 and an outer surface facing in the opposite direction to the internal space 208.

[0165] When the filter element wall 210 is made of a porous material (e.g., porous polyethylene), fluid (e.g., gas or air) enters the internal space 208 of the filter element 204 through the filter element wall 210 and flows out of the internal space 208 through the clean fluid outlet opening 212.

[0166] However, a powder material (i.e., one or more kinds of fine particles dispersed in the carrier fluid injected through the inlet opening 218) cannot pass through the filter element wall 210.

[0167] The filter element material 206 provided with the mounting flange 220 is inserted into the mounting hole 216. At that time, a closed side of the filter element material 206 is extended into the processing space 222, and the clean fluid outlet 212 of the filter element 204 is mounted so that it opens toward the outside of the processing box body housing 214.

[0168] The mounting flange 220 provided with the filter element body is inserted into and mounted to the mounting hole 216 as described below.

[0169] As shown in FIG. 9, the mounting hole 216 and the mounting flange 220, and the mounting flange 220 and the filter element wall 210 fluid seal the processing space 222 against the environment of the processing box body housing 214. For a seal means, a seal means that is outside the scope of common engineering practice, for example a seal ring can also be used.

[0170] Therefore, in a configuration shown in FIG. 9, fluid can only flow out of the processing space 222 through the clean fluid outlet 212 of the filter element 204, as indicated by the arrow B in FIG. 9.

[0171] Due to the orientation of the filter element 204 and the mounting flange 220 shown in FIG. 9, the powder material cannot enter the internal space 208 of the filter element material 206. Rather, the powder material is adhered to the outside of the filter element material 206 to form the dust collection layer 202 on the outside of the filter element 204.

[0172] Therefore, in the processing box body 200 in FIG. 9, the pocket-shaped or bag-shaped filter element 204 is inserted into the processing box body 200 with the outer surface of the filter element 204 exposed to the processing space 222.

[0173] Therefore, the processing box body 200 in FIG. 9 is configured to form the dust collection layer 202 on the outer surface of the pocket-like filter element 204.

[0174] FIG. 10 shows a schematic cross-sectional view of the filter element 204 produced by using the processing box body in FIG. 9.

[0175] A process of forming the dust collection layer 202 on the outside of the pocket-like filter element 204 proceeds as the following steps:

[0176] (i) An aerosol fluid of a mixture powder material of two or more kinds of fine particles constituting the dust collection layer dispersed in pressurized carrier fluid (e.g., air) is injected into the processing space 222 through an inlet opening 218 (see arrow A in FIG. 9).

[0177] (ii) The clean fluid outlet 212 of the filter element material 206 is coupled to a fan, a blower, a pump, or a similar device. The clean fluid outlet 212 sucks a fluid flow (e.g., air) that passes through the filter element wall 210 from the processing space 222 and does not contain any more powder materials.

[0178] Rather, the powder material is applied to the outer surface of the filter element material 206 when the fluid injected into the processing space passes through the processing space 222 through the filter element wall 210.

[0179] (iii) The aerosol in the processing space 222 is sucked in by the fan, the blower, or the pump coupled to the clean fluid outlet 212 of the filter element 204 (see arrow B in FIG. 9). Due to this suction action, the powder mixture dispersed in the carrier fluid in the processing space 222 adheres to the outer surface of the filter element material 206 (more precisely, the outer surface of the filter element wall 210 facing the processing space 222).

[0180] The adhesion of the powder material to the filter element material 206 helps to form the dust collection layer 202 on the outer surface of the filter element 204.

[0181] (iv) The processing box body 200 is provided with a nozzle device 226 with at least one conduit including a plurality of nozzles.

[0182] Fluid pulses are injected into the processing space 222 through the nozzle device 226 (see arrow C in FIG. 9).

[0183] These fluid pulses further help to maintain a well-dispersed and uniformly mixed state of the aerosol of the powder mixture dispersed in the carrier fluid in the processing space 222 until the application of the material for the dust collection layer 202 is completed.

[0184] The installation of such a nozzle device 226 is optional.

[0185] This process enables to provide a uniform distribution of the powder material on the surface of the filter element wall 210, even when the filter element wall 210 has a complex surface shape, for example, when the filter element wall 210 has an undercut portion.

[0186] For example, in the example of the filter element material 206 shown in FIGS. 14 and 15, the filter element wall 210 forming the filter element material 206 includes a lamellar structure 300 having a complex surface shape including a helical structure 302 of a convex portion 304 and a concave portion 306.

[0187] The convex portion 304 and the concave portion 306 form the undercut portion on the outside of the filter element material 206.

[0188] The convex portion 304 and the concave portion 306 also form the undercut portion on the inside of the filter element material 206.

[0189] The rotation of the filter element 204 in the processing box body 200 is an optional means.

[0190] As a result, in the method described above, a process such as a filtration is utilized to adhere the powder mixture in order to form the dust collection layer 202 to the outer surface of the filter element 204.

[0191] After the powder mixture for forming the dust collection layer 202 is adhered to the outer surface of the filter element 204, the filter element 204 is removed from the processing box body 200 and a thermal treatment is subjected as described with reference to the above examples.

[0192] This thermal treatment causes one of the two or more kinds of particles contained in the powder mixture applied to the surface of the filter element material 206 to melt, and the dust collection layer 202 to adhere to the filter element material 206 after the thermal treatment is completed.

[0193] It will be appreciated that more details about the thermal treatment are referred to FIG. 2 and the descriptions, as well as the above-mentioned Example 1.

Example 5

[0194] FIG. 11 shows a schematic view of the processing box body 200 configured to form the dust collection layer 202 on the pocket-like filter element 204 on the inside thereof, according to a further example.

[0195] FIG. 12 shows a schematic cross-sectional view of the filter element produced by using the processing box body in FIG. 11.

[0196] The processing box body in FIG. 11 basically corresponds to the processing box body in FIG. 9.

[0197] Therefore, the same reference numbers as those shown in FIG. 9 are also used in FIG. 11.

[0198] It will be appreciated that components in FIG. 11 that have the same reference numbers as those in FIG. 9 are referred to the above description in FIG. 9 unless otherwise specified.

[0199] The differences between the examples in FIG. 9 and FIG. 11 will be described below.

[0200] As the same in FIG. 9, the processing box body housing 214 has the mounting hole 216 configured to insert and mount the mounting flange 220.

[0201] The filter element material 206 including the dust collection layer 202 is mounted to the mounting flange 220.

[0202] In FIG. 11, the processing box body housing 214 is drawn partially cut away to better show the processing space 222 provided with the mounting flange 220 and the filter element material 206 therein.

[0203] In order to form the dust collection layer 202 on the inside of the pocket-like or bag-like filter element 204, the configuration of the mounting flange 220 is changed with respect to FIG. 9, and the pocket-like or bag-like filter element material 206 is mounted to the mounting flange 220 in a different way.

[0204] Unlike the mounting flange 220 in FIG. 9, the mounting flange 220 in FIG. 11 includes an additional mounting flange receiver 230.

[0205] The mounting flange receiver 230 provides an extension of the mounting flange 220 to the processing box body 222 and is configured to accommodate the filter element material 206 of the filter element 202 to which the dust collection layer 202 is applied.

[0206] As the same with those shown in relation to FIG. 9, the filter element material 206, and thus the filter element 204 is also formed with at least one pocket-like or bag-like structure 310 having a pocket or bag shape.

[0207] The pocket-like or bag-like structure 310 defines the internal space 208 of the filter element material 206 or the filter element 204.

[0208] The internal space 208 is enclosed by at least one filter element wall 210 (see FIG. 12).

[0209] Therefore, the filter element 204 has an inner surface facing the internal space 208 and an outer surface facing in the opposite direction to the internal space 208.

[0210] In particular, the same filter element material 206 used in the example in FIG. 9 may also be used in the example in FIG. 11.

[0211] However, in the example in FIG. 11, the filter element material 206 is mounted to the mounting flange receiver 230 of the mounting flange 220 in a different orientation, i.e., an orientation such that at least one filter element wall 210 completely encloses the internal space 208, except for at least one raw material fluid inlet opening 228.

[0212] The raw material fluid inlet opening 228 is open towards the processing space 222.

[0213] Therefore, the aerosol (i.e., carrier fluid in which the powder mixture is dispersed, for example gas or air) in the processing space 222 flows into the internal space 208 of the filter element material 206 through the raw material fluid inlet opening 228.

[0214] When the filter element wall 210 is made of porous material (e.g., porous polyethylene), the fluid phase of the aerosol (e.g., gas or air) can pass through the filter element wall 210 and flow into a space 234 formed between the outer surface of the filter element material 206 and the mounting flange receiver 230.

[0215] The space 234 is in fluid communication with the fan, the blower, or the pump that draws the fluid out of the space 234 through a mounting flange outlet 238.

[0216] The mounting flange receiver 230, into which the filter element material 206 is inserted, is mounted into the mounting hole 216 as follows.

[0217] As shown in FIG. 11, the mounting hole 216 and the mounting flange 220 seal the processing space 222 airtight from the periphery of the processing box body housing 214. The mounting flange receiver 230 and the filter element material 206 seal the processing space 222 airtight against the space 234 formed between the outer side of the filter element material 206 and the mounting flange receiver 230. As a sealing means, a sealing means that is not in line with general engineering practice, for example a sealing ring, can also be used.

[0218] Therefore, in the configuration shown in FIG. 11, fluid passes through the filter element wall 210, as indicated by arrow B in FIG. 11, and after reaching the space 234 formed between the outside of the filter element material 206 and the mounting flange receiver 230, it can flow out of the processing space 222 only through the mounting flange outlet 238.

[0219] However, since the filter element wall 210 is not permeable to the powder material, the powder material cannot escape from the processing space 222 at all.

[0220] As the same with the orientation of the filter element 204 and the mounting flange 220 shown in FIG. 11, although only the fluid phase of the aerosol injected into the processing space 222 can pass through the filter element wall 210, the powder material (i.e., one or more kinds of fine particles dispersed in the carrier fluid injected through the inlet opening 218) cannot pass through the filter element wall 210, and thus the powder material adheres on the inside of the filter element material 206.

[0221] The adhesion of the powder on the inside of the filter element 204 helps to form the dust collection layer 202 on the inside of the filter element 204.

[0222] Therefore, in the processing box body 200 in FIG. 11, the pocket-like or bag-like filter element 204 is inserted into the processing box body 200 with the inside of the filter element 204 exposed to the processing space 222.

[0223] Therefore, the processing box body 200 in FIG. 11 is configured to form the dust collection layer 202 on the inside of the pocket-like filter element 204.

[0224] FIG. 12 shows a schematic cross-sectional view of the filter element produced by using the processing box body in FIG. 11.

[0225] The remaining process steps are the same as those described above with regard to the examples in FIGS. 9 and 10.

[0226] The dust collection layer 202 is secured to the filter element material 206 by referring to the above processes (i)-(iv) and the subsequent heating process.

Example 6

[0227] FIG. 13 shows a schematic view of the processing box body 200 configured to form the dust collection layer 202 on the pocket-like filter element 204 on the inside thereof, according to a further example.

[0228] FIG. 10 shows a schematic cross-sectional view of the filter element produced by using the processing box body in FIG. 13.

[0229] The processing box body in FIG. 13 basically corresponds to the processing box body in FIG. 11.

[0230] Therefore, the same reference numbers are also used in FIG. 13 as shown in FIG. 11.

[0231] Unless otherwise specified, it will be appreciated that components in FIG. 13 that have the same reference numbers as those shown in FIG. 11 are referred to the description in FIG. 11 above.

[0232] The differences between the examples in FIG. 11 and FIG. 13 will be described below.

[0233] As the same with those shown in relation to FIG. 11, the filter element material 206, and thus the filter element 204 is also formed with at least one pocket-like or bag-like structure 310 having a pocket or bag shape.

[0234] The pocket-like or bag-like structure 310 defines the inner space 208 of the filter element material 206 or the filter element 204.

[0235] The internal space 208 is enclosed by at least one filter element wall 210 (see FIG. 12).

[0236] Therefore, the filter element 204 has an inner surface facing the internal space 208 and an outer surface facing in the opposite direction to the internal space 208.

[0237] In particular, the same filter element material 206 as used in the examples in FIGS. 11 and 12 may also be used in the example in FIG. 13.

[0238] However, in the example in FIG. 13, the filter element material 206 is mounted to the mounting flange 220, i.e., from the outside of the processing box body housing 214, and in an orientation such that at least one filter element wall 210 completely encloses the internal space 208, except for at least one raw material fluid inlet opening 228.

[0239] The raw material fluid inlet opening 228 is open towards the processing space 222.

[0240] Therefore, an aerosol (i.e., carrier fluid, in which the powder mixture is dispersed, for example gas or air) in the processing space 222 can enter the internal space 208 of the filter element material 206 through the raw material fluid inlet opening 228.

[0241] Since the filter element wall 210 is made of porous material (e.g., porous polyethylene), the fluid phase of the aerosol (e.g., gas or air) can pass through the filter element wall 210 and flow into the external space outside the filter element 204.

[0242] From the external space outside the filter element 204, the fluid phase is sucked in by the action of a fan, a blower, or a pump that draws the fluid from the external space. For example, the processing box body housing 214 and the filter element 204 can be inserted into a second housing 236 coupled to the fan, the blower, or the pump.

[0243] The example in FIG. 13 does not require the mounting flange receiver 230 as described in relation to the example in FIG. 11.

[0244] In the processing chamber 290 in FIG. 13, the filter element 204 having a pocket or a bag shape is secured to the processing box body 200 by being fitted to the processing box body housing 214 so that the inside of the filter element 204 is exposed to the processing space 222, in the same way as the processing box body 200 in FIG. 11.

[0245] Therefore, the processing chamber 290 in FIG. 13 is configured to form the dust collection layer 202 inside the pocket-like filter element 204.

[0246] The remaining process steps are the same as those described above for the examples of FIGS. 11 and 12.

[0247] Referring to the above processes (i)-(v) and the subsequent heating process, the dust collection layer 202 is secured to the filter element material 206.

Example 7

[0248] FIG. 14 shows three different perspective views of the filter element material 206 to which the dust collection layer 202 can be applied on the inside and/or the outside of the filter element material 206, in accordance with any one of examples according to the present invention.

[0249] The filter element material 206, and thus the filter element 204 is also formed with the pocket-like or bag-like structure 310 having a pocket or bag shape.

[0250] The pocket-like or bag-like structure 310 defines the internal space 208 of the filter element material 206 or the filter element 204.

[0251] The internal space 208 is enclosed by at least one filter element wall 210 (see FIG. 10 or 12).

[0252] Therefore, the filter element 204 or the filter element material 206 has an inside facing the internal space 208 and an outside facing in the opposite direction to the internal space 208.

[0253] As described in Example 4, the dust collection layer 202 can be formed on the outer surface of the filter element material 206 to produce the filter element having the dust collection layer 202 on the outer surface thereof.

[0254] Alternatively or additionally, as described with respect to Examples 5 and 6, the dust collection layer 202 may be formed on the inside of the filter element material 206 to produce the filter element having the dust collection layer 202 on the inside thereof.

[0255] The filter element material 206 is formed with at least one filter element wall 210 defining the lamella structure 300.

[0256] The lamella structure 300 includes a complex geometric configuration of the convex portion 304 and the concave portion 306 on the outside of at least one filter element wall 210.

[0257] Alternatively, the lamella structure 300 includes a complex geometric configuration of the convex portion 304 and the concave portion 306 and may include at least one concave portion 306 on the inside of at least one filter element wall 210.

[0258] In particular, as shown in FIG. 14, the lamellar structure 300 includes a complementary geometric configuration including a plurality of the convex portions 304 and the concave portions 306 on both the outside and inside of at least one filter element wall 210.

[0259] The convex portion 304 and the concave portion 306 of at least one filter element wall 210 are shaped to form at least one undercut portion 308 of the geometric configuration.

[0260] A particular advantage of the filter element wall 210 defining the lamellar structure 300 is that it allows to provide a relatively large filter surface area for a given volume of the filter element material 206.

[0261] However, it is usually difficult to apply the dust collection layer to such a surface of the filter element material 206, especially when the lamellar structure 300 includes an undercut portion 308 or when it has a plurality of undercut portions 308.

[0262] Conventional coating methods have not been able to form the sufficiently uniform dust collection layer 202 on the filter element material 206 having such a complex geometric configuration.

[0263] However, a dry coating method according to the present invention has provided for the first time a method for forming the sufficiently uniform dust collection layer 202 on the filter element material 206 having a complex geometric configuration, such as the lamella structure 300 having the convex portion 304 and the concave portion 306 having at least one undercut portion 308, as described herein.

[0264] In the specific example shown in FIG. 14, the geometric configuration of the lamellar structure includes the helical structure 302.

[0265] The convex portion 304 and the concave portion 306 of at least one filter element wall 210 are shaped to form the helical structure of the lamellar structure.

[0266] The filter element material 206, and thus the filter element 204 are also formed with at least one pocket-like or bag-like structure 310 having a cylindrical shape.

[0267] In another example, the filter element material 206, and thus the filter element 204 can also be formed to have a cone, a truncated cone, or other rotationally symmetric shape defined by at least one filter element wall 210.

[0268] The term rotationally symmetric shape is intended to indicate any shapes having a rotational symmetry along the vertical axis of the filter element material 206.

[0269] The filter element material 206 having such a complex geometric shape can be produced by a sintering process, for example, by sintering polymer particles, particularly polyethylene particles.

Example 8

[0270] FIG. 15 shows a different view of the additional filter element material 206, in which the dust collection layer 202 can be formed on the inside and/or the outside of the filter element material 206, in accordance with any one of examples according to the present invention.

[0271] In the example in FIG. 15, the filter element material 206, and thus the filter element 204 are also formed with a plurality of pocket-like or bag-like structures 310.

[0272] Each of these pocket-like or bag-like structures 310 has a pocket or bag shape.

[0273] The pocket-like or bag-like structure 310 divides the internal space 208 of the filter element material 206 or the filter element 204.

[0274] The internal space 208 is enclosed by at least one filter element wall 210.

[0275] Therefore, the filter element 204 or the filter element material 206 has an inner surface facing the inner space 208 and an outer surface facing in the opposite direction to the inner space 208.

[0276] The above matters to be considered described in relation to FIG. 14 also apply in relation to the example in FIG. 15. Therefore, it will be appreciated that these considerations are also referred.

Example 9

[0277] In accordance with Example 4, a filter element was produced by subjecting a cylindrical filter element material to a process of forming a dust collection layer in a processing box body.

[0278] Next, a dust collection load confirmation test was conducted to this filter element by using the dust collection load test device in FIG. 7.

[0279] The filter element material was produced by sintering polyethylene particles.

[0280] The filter element material had a cylindrical shape having a filter element wall that was almost cylindrical.

[0281] The filter element wall, which was approximately cylindrical, was provided with a lamella structure having a helical shape.

[0282] The lamella structure was formed with a plurality of helical convex and concave portions, as shown in FIG. 14.

[0283] The filter element body had a diameter of 137 mm and a length of 220 mm.

[0284] After inserting the filter element body into the processing chamber in FIG. 14, a fine particle mixture was flowed into the processing box body to form a dust collection layer on the filter element body.

[0285] The mixture of fine particles was made of 60% by weight of LLDPE (linear low-density polyethylene, D50=45 m) and 40% by weight of UHMWPE (ultra-high-molecular-weight polyethylene, D50=10 m).

[0286] The mixture did not contain PTFE.

[0287] The processing steps followed the steps described in relation to Example 1 and the description above in relation to Example 4.

[0288] The produced filter element had a filtration surface of 0.15 m.sup.2.

[0289] The filter element was inserted into the dust load collection test device in FIG. 7.

[0290] The test parameters were as follows: [0291] Filter surface: 0.15 m.sup.2 [0292] Dust collection load: 1.5 kg clay slate, [0293] equivalent to 2.01 in volume [0294] Air flow: 107.1 m.sup.3/s (start of test)-84 m.sup.3/s (end of test) [0295] Mass flow of dust: 60 g/s [0296] Feed concentration of dust: 2017.0 g/m.sup.3 [0297] Pulse cleaning cycle: 28 seconds [0298] Pulse cleaning duration: 2 seconds [0299] Pressure of cleaning pulse: 0.9 bar [0300] Test period: 2880 cycles=191 hours [0301] Total amount of dust conveyed: 34380 kg

[0302] The pressure loss of the filter element after the pressure cleaning cycle was as follows. [0303] Initial pressure loss: 1750 Pa [0304] Pressure loss after 5 minutes: 2650 Pa [0305] Pressure loss after 30 minutes: 2800 Pa [0306] Pressure loss after 1 hour: 3600 Pa [0307] Pressure loss after 2 hours: 3850 Pa [0308] Pressure loss after 17 hours: 5450 Pa [0309] Pressure loss after 41 hours: 6150 Pa [0310] Pressure loss after 43 hours: 6150 Pa [0311] Pressure loss after 67 hours: 6400 Pa [0312] Pressure loss after 89 hours: 6600 Pa [0313] Pressure loss after 161 hours: 6600 Pa [0314] Pressure loss after 185 hours: 6600 Pa [0315] Pressure loss after 191 hours: 6600 Pa

[0316] The above pressure loss over time is graphed and shown in FIG. 16.

[0317] The maximum dust concentration measured in the clean gas downstream of the filter element was as follows: [0318] 10 minutes later: 0.099 mg/m.sup.2 [0319] 1 hour later: 0.071 mg/m.sup.2 [0320] 43 hours later: 0.099 mg/m.sup.2 The dust concentration was measured by using Hund (registered trademark) Data II device manufactured by Helmut Hund GmbH at Wetzlar, Germany.

[0321] After dismantling the filter element from the dust collection load test device, no traces of the dust substances contaminated in the material of the filter element was found.

REFERENCE SIGNS LIST

[0322] 10 sintered lamellar dust collector [0323] 12 casing [0324] 14 upper top panel [0325] 16 dust collection chamber [0326] 18 clean air chamber [0327] 20 supply port for dust-containing air [0328] 22 exhaust port for the clean air [0329] 24 filter element [0330] 24a hollow chamber [0331] 26 hopper [0332] 28 outlet for dust [0333] 32 large diameter part [0334] 34 frame [0335] 36 fastening bolt [0336] 38 packing [0337] 91 aerosol blowoff port [0338] 92 compressed air blowoff port [0339] 93 dust collection layer composition powder [0340] 100 fan [0341] 101 quantitative supply device [0342] 102 upper tank [0343] 103 upper clean air chamber [0344] 104 dust conveyance device [0345] 105 lower tank [0346] 106 testing filter element [0347] 107 lower dust collection chamber [0348] 108 upper top plate [0349] 109 hopper [0350] 200 processing box body [0351] 202 dust collection layer [0352] 204 filter element [0353] 206 filter element material [0354] 208 internal space [0355] 210 filter element wall [0356] 212 clean air outlet [0357] 214 processing box body housing [0358] 216 mounting hole [0359] 218 inlet opening [0360] 220 mounting flange [0361] 222 processing space [0362] 226 nozzle device [0363] 228 raw material fluid inlet opening [0364] 230 mounting flange receiver [0365] 234 space between filter element and mounting flange receiver [0366] 236 second housing [0367] 238 mounting flange outlet [0368] 290 the processing chamber [0369] 300 lamellar structure [0370] 302 helical structure [0371] 304 convex portion [0372] 306 concave portion [0373] 308 undercut portion [0374] 310 pocket-like or bag-like structure