Treatment of particle filters

Abstract

A method and apparatus (1) for applying dry powder to a porous substrate (10): a) positioning the porous substrate (10) in a holder (2) such that an inlet face (11) is in communication with an inlet chamber (15) and an outlet face (12) is in communication with a vacuum generator; b) establishing a gas flow through the porous substrate (10) from the inlet face (11) to the outlet face (12) by applying a reduced pressure to the outlet face (12) using a vacuum generator; c) spraying a dry powder to entrain it in a gas stream and passing it through the inlet face (11) to contact the porous structure (13) of the porous substrate (10); and d) activating the annular air blade (30) to blow off the dry powder accumulated on the inlet face (11), where the vacuum generator remains active during activation of the annular air blade (30) such that the dry powder blown off from the inlet face (11) is entrained in a gas stream and passes through the inlet face (11) of the porous substrate (10).

Description

[0001] This disclosure relates to methods and apparatus for applying dry powder to a porous substrate. In some embodiments, the invention relates to improvements in methods and apparatus for coating filters, the filters comprising a porous substrate having an inlet face and an outlet face, wherein the inlet face is separated from the outlet face by a porous structure. The filter may be a wall-flow filter. Background Technology

[0002] EP 4013954 A1 describes a method and apparatus for treating a filter used to filter particulate matter from exhaust gas, the method comprising the steps of: a) containing dry powder in a reservoir; b) positioning a filter in a filter holder, the filter comprising a porous substrate having an inlet face and an outlet face separated by a porous structure; c) establishing a main gas flow through the porous structure of the filter by applying a pressure reduction to the outlet face of the filter; d) transferring the dry powder from the reservoir to a spraying device located upstream of the inlet face of the filter; and e) spraying the dry powder toward the inlet face of the filter using the spraying device such that the dry powder is entrained in the main gas flow and passes through the inlet face of the filter to contact the porous structure.

[0003] While the method and apparatus have proven effective in loading dry powder into porous structures, accumulation of dry powder on the filter's inlet face can occur during spraying. This leads to reduced dry powder utilization efficiency and potentially clogs the channels due to powder buildup at the inlet face after filter calcination, thereby increasing the filter's scrap rate.

[0004] WO 2021 / 160572 A1 describes the use of ultrasonic waves to clean dried deposits from the coating of a wall-flow filter plug. Specifically, ultrasonic electrodes and additional reflectors are used to generate sound pressure waves to clean dried deposits from the inlet face of the wall-flow filter.

[0005] However, the use of ultrasonic welding electrodes can be expensive in practice and requires careful setup, maintenance, and operator knowledge to be used effectively. In practice, ensuring that the ultrasonic welding electrode is guided across the entire surface of the entry face can be complex, and while additional reflectors can be used, these increase the cost of the system and may also suppress or impede the incoming gas flow and dry powder during spraying, potentially leading to reduced uniformity of dry powder application.

[0006] This disclosure attempts to address at least some of the problems associated with the prior art or to provide at least a commercially acceptable alternative solution. Summary of the Invention

[0007] In a first aspect, this disclosure provides a method for applying dry powder to a porous substrate having an inlet face and an outlet face, wherein the inlet face and the outlet face are separated by a porous structure, the method comprising the following steps:

[0008] a) Position the porous substrate in the retainer such that the inlet face is in communication with the inlet chamber and the outlet face is in communication with the vacuum generator;

[0009] b) By using the vacuum generator to apply pressure to the outlet surface of the porous substrate, a gas flow from the inlet surface to the outlet surface through the porous substrate is established;

[0010] c) Spraying the dry powder into the inlet chamber or spraying the dry powder into the inlet chamber, such that the dry powder is entrained in the gas flow and passes through the inlet surface of the porous substrate to contact the porous structure; and

[0011] d) Activate the annular air vane to blow away dry powder accumulated on the inlet surface of the porous substrate, wherein the vacuum generator remains active during the activation of the annular air vane, such that the dry powder blown away from the inlet surface is entrained in the gas flow and passes through the inlet surface of the porous substrate.

[0012] Advantageously, the use of the annular air vane provides a practical, easy-to-operate, and low-maintenance means for cleaning the inlet face of the porous substrate. The annular air vane may not require any electricity during use and does not obstruct the gas flow when it approaches the inlet face. Advantageously, keeping the vacuum generator active during the operation of the annular air vane increases the utilization rate of the dry powder by allowing it to enter the porous structure through the inlet face.

[0013] In some embodiments, the annular air vane is activated to blow away the dry powder after the application of dry powder into or into the inlet chamber has been stopped. Alternatively or additionally, the annular air vane may be activated during the application of dry powder into or into the inlet chamber.

[0014] The annular air vane can be oriented to guide a gas flow at a downward angle toward the inlet face of a porous substrate. For example, the annular air vane may include a shaped outlet that uses the Coanda effect to deflect a radially inward gas flow downward to create a tapered gas flow that can be guided toward the inlet face.

[0015] The annular air vane can emit a gas flow of 360° or substantially 360°. In some embodiments, the annular air vane may include two semi-circular elements, each supplied with gas from an inlet. When these two elements are combined, a complete ring can be formed surrounding the inlet face. With two elements, the outlet opening may not extend a full 360° due to the presence of end walls. However, it will be understood that the emitted gas flow will still extend around approximately 360°.

[0016] The plane of the gas outlet of the annular air blade can be positioned between 1 cm and 10 cm above the plane of the inlet surface.

[0017] The annular air blade may be located within the inlet chamber or between the inlet chamber and the inlet surface of the porous substrate, or arranged in series between portions of the inlet chamber. In some embodiments, the outer diameter of the annular air blade may be smaller than that of the inlet chamber and it may be concentrically located within the inlet chamber. In other embodiments, the annular air blade may have an outer diameter similar to that of the inlet chamber and may be stacked in series between the inlet chamber and the inlet surface of the porous substrate.

[0018] The inlet chamber may be, for example, a tube, optionally having an open upper end. The lower end of the tube may be in fluid communication with the inlet surface of the porous substrate.

[0019] Gas can be supplied to the annular air blade at pressures up to 8 bar, optionally at 3 to 8 bar, optionally at 3 to 6 bar, optionally at 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, 7 bar, or 8 bar. In some embodiments, a minimum pressure of 2 bar has been found to be effective in blowing away the dry powder.

[0020] The annular air blade can emit gas at a flow rate greater than 150 liters / minute, optionally greater than 200 liters / minute, or optionally greater than 250 liters / minute.

[0021] The dry powder can be sprayed into the inlet chamber using a spraying device, or optionally using a nozzle, or sprayed into the inlet chamber. The nozzle can use a gas flow to entrain the dry powder during spraying. For example, the spraying device includes a compressed air gun. A non-limiting example of a suitable compressed air gun is the STAR Professional Gravity Feed Spray Gun 1.4mm, part number STA2591100C.

[0022] The spraying device can be located at a distance of 50cm to 250cm from the inlet surface, optionally at a distance of 50cm to 200cm from the inlet surface, optionally at a distance of 100cm to 200cm from the inlet surface, optionally at a distance of 150cm to 200cm from the inlet surface, or optionally at a distance of 200cm from the inlet surface.

[0023] The gas flow generated by the vacuum generator can be an air flow or other suitable gas flow. The annular air blade can be supplied with pressurized air or other suitable gas.

[0024] In a second aspect, this disclosure provides an apparatus for applying dry powder to a porous substrate having an inlet face and an outlet face, wherein the inlet face and the outlet face are separated by a porous structure, the apparatus comprising:

[0025] a) A retainer for holding the porous substrate;

[0026] b) An entrance chamber that is connected to the entrance face;

[0027] c) A vacuum generator connected to the outlet surface and used to establish a gas flow from the inlet surface to the outlet surface through the porous substrate;

[0028] d) A spraying apparatus for spraying the dry powder into or within the inlet chamber; and

[0029] e) Annular air blades.

[0030] As noted above, the annular air vane can be oriented to guide a gas flow at a downward angle to the inlet face of the porous substrate when the porous substrate is located in the retainer, to blow away dry powder that may accumulate on the inlet face of the porous substrate. The annular air vane can be configured to emit a 360° or substantially 360° gas flow. The plane of the gas outlet of the annular air vane can be positioned between 1 cm and 10 cm above the plane of the inlet face. The annular air vane can be located in the inlet chamber or between the inlet chamber and the inlet face of the porous substrate. The spraying device may include a nozzle. The spraying device can be located at a distance of 50 cm to 250 cm from the inlet face, optionally at a distance of 50 cm to 200 cm, optionally at a distance of 100 cm to 200 cm, optionally at a distance of 150 cm to 200 cm, optionally at a distance of 200 cm.

[0031] In this specification, the term "dry powder" refers to a particulate composition that is not suspended or dissolved in a liquid. This does not necessarily mean the complete absence of all water molecules. The dry powder is preferably free-flowing.

[0032] In some embodiments, the dry powder may contain or be composed of silicone resin. Silicone resins are known and are branched cage-like oligomeric siloxanes and polysiloxanes. The branching in silicone resins is due to the presence of so-called "T" and / or "Q" units in the resin, which refer to RSiO3 and SiO4 units respectively (R being alkyl or aryl), where additional silicon units are bonded to oxygen atoms. "M" units (i.e., R3SiO units) are terminal units where oxygen atoms provide a connection to the resin backbone. Similarly, "D" units (i.e., R2SiO2 units) provide a linear connection across two oxygen atoms. A well-known unbranched and linear polysiloxane is polydimethylsiloxane (PDMS; i.e., (Me2SiO)). n ).

[0033] Preferably, the silicone resin is solid at room temperature (e.g., about 25°C). Therefore, the silicone resin preferably has a melting point greater than 25°C, more preferably greater than 30°C, and more preferably greater than 35°C. Preferably, the silicone resin has a melting point less than 100°C, more preferably less than 95°C, less than 90°C, less than 85°C, or less than 80°C. Unbranched polysiloxanes such as PDMS typically have lower melting points than branched silicone resins. For example, the melting point of PDMS is about -40°C. WO 2011 / 151711 discloses treating a powder bonded at the appropriate location with a polydimethylsiloxane, which hydrolyzes at a sufficiently high temperature to form silica.

[0034] Similarly, it is preferable that the silicone resin has a glass transition temperature (T0) greater than 30°C, preferably greater than 35°C, and / or less than 100°C, preferably less than 80°C. g Without being bound by theory, silicone resins believed to have such melting points and / or glass transition temperatures are particularly suitable for powder coating processes, i.e., for effective particle dispersion across porous substrates, but with melting points and / or glass transition temperatures low enough to allow for low-temperature calcination, thereby effectively and efficiently adhering inorganic particles to the gas contact surfaces of the channel walls of porous substrates.

[0035] Preferably, the silicone resin has a molecular weight greater than 1,000, preferably greater than 2,000, preferably greater than 5,000, preferably greater than 10,000, and / or less than 500,000, preferably less than 200,000.

[0036] As used in this article, molecular weight refers to weight-average molecular weight (M). WThe molecular weight can be measured using any conventional apparatus in the art. In some embodiments, the molecular weight may be relatively low because the hydrogen bonding provided by the hydroxyl functional groups gives the silicone resin a sufficiently high melting point and / or glass transition temperature. Thus, in some embodiments, the molecular weight of the silicone resin may be 1,000 to 10,000, preferably 1,000 to 5,000, preferably 1,200 to 3,500, such as 1,500 to 2,000. Silicone resins with a molecular weight below 1,000 are less preferred because these silicone resins are typically liquid and not suitable for dry spraying, or do not have as much branching as larger molecules, which are believed to enhance the bonding of inorganic particles to porous substrates.

[0037] However, the molecular weight of the silicone resin is preferably from 15,000 to 150,000, preferably from 20,000 to 120,000, and preferably from 60,000 to 100,000. Some preferred resins have an M value of 8,000 to 15,000. w Some resins have a value of 20,000 to 60,000, while others have a value of 80,000 to 120,000.

[0038] Particularly preferred is that the organosilicon resin has the formula [R] x SiX y O z ] n Where R is an alkyl or aryl group, X is a functional group bonded to silicon, and z is greater than 1 and less than 2. As will be understood, n is large in order to provide the desired oligomers or polymers of silicone resins, particularly resins that are solid at room temperature. Although dependent on the molecular weight of the R and X groups, when n is greater than 10, M > 1,000 can be obtained. W When n is greater than 100, an M greater than 10,000 can be obtained. W Furthermore, when n is greater than 1,000, an M greater than 100,000 can be obtained. W Therefore, n can preferably be greater than 10, greater than 100, or greater than 1,000.

[0039] As will be understood, R is an alkyl or aryl group bonded to silicon, and X is a non-hydrocarbon functional group bonded to silicon. Similarly, since silicon is a tetravalent atom, it should be understood that x + y + 2z = 4. z is less than 2 because where z = 2, x and y = 0, providing silicon dioxide (i.e., silicon dioxide; (SiO2)). n Similarly, z is greater than 1 because where z = 1, x + y = 2, resulting in substituted polysiloxanes (e.g., (RXSiO)) composed of "D" units. nThis yields linear resins (e.g., –O–(SiRX)–O–(SiRX)–O–). One example is polydimethylsiloxane. Therefore, O refers to the oxygen atom bridging two silicon atoms in the polymer backbone of the silicone resin.

[0040] Preferably, 0 < x + y < 2, preferably 0 < x + y ≤ 1.5, preferably 0 < x + y ≤ 1. Preferably, x, y, and / or x + y are greater than 0.1, preferably greater than 0.2. In a preferred embodiment, x + y is 1, resulting in an organosilicon resin commonly referred to as polysilsesquioxane. Preferably, y is less than 1 and / or y is less than x. Even more preferably, 2y ≤ x, preferably 5y ≤ x, preferably 10y ≤ x. In one embodiment, y is 0. For example, y is 0, wherein the polysilsesquioxane is a polyalkylsilsesquioxane, such as polymethylsilsesquioxane (MeSiO2). 3 / 2 ) n .

[0041] Typically, when present, X is one or more of H, hydroxyl (OH), Cl, and C1–C6 alkoxy groups, preferably one or more of OH and C1–C6 alkoxy groups, preferably wherein the C1–C6 alkoxy groups are selected from methoxy (OCH3) and ethoxy (OCH2CH3). In a particularly preferred embodiment, X is one or both of OH and ethoxy. However, X is a functional group, which can also be a reactive functional group, such as an amino group (NH2, NR2), an epoxy group, an acrylate group, and a vinyl group, but these functional groups are less preferred because the presence of hydroxyl or alkoxy groups is considered to provide more efficient crosslinking during calcination. As mentioned above, any oxygen present in the terminal functional group corresponds to the "O" in the above formula. z "No one contributed, the 'O'" z "" refers to silicon bridging oxygen atoms.

[0042] In some embodiments, the dry powder may contain or consist of zeolite. Zeolite is a structure formed from alumina and silica, and SAR determines the reactive sites within the zeolite structure. Zeolite may be a microporous zeolite (e.g., a zeolite with a maximum ring size of eight tetrahedral atoms), a mesoporous zeolite (e.g., a zeolite with a maximum ring size of ten tetrahedral atoms), or a macroporous zeolite (e.g., a zeolite with a maximum ring size of twelve tetrahedral atoms), or a combination of two or more of these.

[0043] Examples of suitable zeolites include silicate zeolites, aluminosilicate zeolites, metal-substituted aluminosilicate zeolites, AlPO, MeAlPO, SAPO, MeAPSO, etc. In some embodiments, the zeolite is selected from aluminosilicate zeolites, borosilicate zeolites, gallium silicate zeolites, SAPO zeolites, AlPO zeolites, MeAPSO zeolites, and MeAPO zeolites.

[0044] When the zeolite is a microporous zeolite, it may have a skeletal structure represented by a skeletal type code (FTC) selected from the group consisting of: ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, LTA, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SFW, SIV, THO, TSC, UEI, UFI, VNI, YUG, and ZON, or mixtures and / or combinations and / or commensal forms of two or more of these. In some embodiments, the microporous zeolite has a skeletal structure selected from the group consisting of: CHA, LEV, AEI, AFX, ERI, LTA, SFW, KFI, DDR, and ITE. In some embodiments, the pore zeolite has a framework structure selected from the group consisting of (e.g., composed of) the following: CHA and AEI. The pore zeolite may have a CHA framework structure.

[0045] In the case of mesoporous zeolite, the mesoporous zeolite may have a skeletal structure represented by a skeletal type code (FTC) selected from the group consisting of (e.g., composed of) the following: AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, and WEN, or a mixture of two or more of them and / or commensal organisms. In some embodiments, the mesoporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) FER, MEL, MFI, and STT. In some embodiments, the mesoporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) FER and MFI, specifically MFI. When the mesoporous molecular sieve has an FER or MFI framework, the zeolite can be magnesium alkali zeolite, silica rock, or ZSM-5.

[0046] In the case of macroporous zeolite, macroporous zeolite may have a skeletal structure represented by a skeletal type code (FTC) selected from the group consisting of (e.g., composed of) the following: AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OKO, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, and VET, or mixtures and / or commensal forms of two or more of these. In some embodiments, the macroporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) the following: AFI, BEA, MAZ, MOR, and OFF. In some embodiments, the macroporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) the following: BEA, MOR, and FAU. When the macroporous molecules have a framework structure of FTC BEA, FAU, or MOR, the zeolite can be a β-zeolite, octahedral zeolite, Y-type zeolite, X-type zeolite, or mordenite.

[0047] In some embodiments, the zeolite has a framework type selected from the following: ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, SCO, C FI, SGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, IFY, IHW, IRN, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU , LEV, LIO, LIT, LOS, LOV, LTA, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MSO, MTF, MTN, M TT, MTW, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SFW, SGT, SOD, SOS , SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, WI, VNI, VSV, WIE, WEN, YUG, ZON, or their combination. In some embodiments, the zeolite has a framework type selected from the following: AEI, AFT, AFV, AFX, AVL, BEA, CHA, DDR, EAB, EEI, ERI, FAU, FER, IFY, IRN, KFI, LEV, LTA, LTN, MER, MOR, MWF, MFI, NPT, PAU, RHO, RIE, RTH, SAS, SAT, SAV, SFW, TSC, and UFI.

[0048] In another embodiment, the inorganic particles are refractory oxide particles, which may be based on oxides selected from the group consisting of: alumina, silica, zirconium oxide, cerium dioxide, chromium oxide, magnesium oxide, calcium oxide, titanium dioxide, and mixtures of any two or more of these. Preferably, the refractory oxide particles include calcium aluminate, pyrolytic alumina, pyrolytic silica, pyrolytic titanium dioxide, pyrolytic zirconium oxide, pyrolytic cerium dioxide, alumina aerogel, silica aerogel, titanium dioxide aerogel, zirconium oxide aerogel, cerium dioxide aerogel, or mixtures thereof. The one or more refractory powders (refractory oxide particles) can be produced by a pyrochemical process, such as flame pyrolysis.

[0049] In some embodiments, the dry powder may contain or consist of a metal compound for forming a metal oxide through thermal decomposition. The dry powder may consist of a single metal compound, or may consist of a mixture or blend, or a continuous dose of two or more metal compounds. The metal compound, or each metal compound, may contain one or more metal cations. In the presence of multiple metal cations, these metal compounds may use the same or different metals. The metal compound may contain or consist of: metal hydroxides, metal phosphates, metal carbonates, metal sulfates, metal perchlorates, metal iodides, metal oxalates, metal acetates, metal chlorates, or mixtures thereof. The metal of the metal compound may contain or consist of: magnesium, calcium, strontium, barium, aluminum, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium, or more than one or more of these. The dry powder may additionally contain metal oxides or mixed metal oxides. Optionally, the dry powder contains 90% by weight or more of a metal compound for forming a metal oxide through thermal decomposition, and 10% by weight or less of a metal oxide or mixed metal oxide. Optionally, the dry powder contains 95% by weight or more of a metal compound for forming a metal oxide by thermal decomposition, and 5% by weight or less of a metal oxide or mixed metal oxide. Optionally, the dry powder contains 99% by weight or more of a metal compound for forming a metal oxide by thermal decomposition, and 1% by weight or less of a metal oxide or mixed metal oxide. The metal in the metal oxide or mixed metal oxide may contain or consist of one or more of the following: aluminum, magnesium, calcium, strontium, barium, aluminum, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium. Optionally, the dry powder contains or consists of the following: metal hydroxides, metal phosphates, metal carbonates, or mixtures thereof. Metal hydroxides may be selected from the group consisting of: magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. Metal phosphates may be selected from the group consisting of: magnesium phosphate, calcium phosphate, strontium phosphate, and barium phosphate. Metal carbonates may be selected from the group consisting of: magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate.

[0050] Dry powder can consist of a single powder type or a mixture of powder types. For example, dry powder may contain or consist of a mixture of zeolite and silicone resin.

[0051] Porous substrates can be, for example, flow-through monolithic materials or filters. In this specification, the term "filter" refers to a porous substrate having a porous structure suitable for filtering particulate matter from exhaust gases. Porous substrates can be formed, for example, from sintered metals, ceramics, or metal fibers. Filters can be wall-flow type made of porous materials (e.g., ceramics), manufactured as a monolithic array of numerous small channels extending along the length of the substrate. For example, filters can be formed from cordierite, various forms of silicon carbide, or aluminum titanate.

[0052] The filter can be a "bare" filter or alternatively a filter with incorporated catalytic capabilities, such as oxidation, NOx capture, or selective catalytic reduction activity. The porous substrate can include a composition of porous structures coated on the filter (referred to as a support coating). The support coating can be a catalytic support coating. The catalytic support coating can include catalysts selected from the group consisting of: hydrocarbon traps, three-way catalysts (TWCs), NOx absorbers, oxidation catalysts, selective catalytic reduction (SCR) catalysts, lean NOx catalysts, and any combination of two or more of these. The catalyst (e.g., TWCs, NOx absorbers, oxidation catalysts, hydrocarbon traps, and lean NOx catalysts) may contain one or more platinum group metals, particularly those selected from the group consisting of platinum, palladium, and rhodium.

[0053] The filter may be, for example, a diesel particulate filter (DPF), a catalytic soot filter (CSF), a selective catalytic reduction filter (SCRF), a lean NOx trap filter (LNTF), a gasoline particulate filter (GPF), an ammonia leak catalyst filter (ASCF), or a combination of two or more of these (e.g., a filter that includes a selective catalytic reduction (SCR) catalyst and an ammonia leak catalyst (ASC).

[0054] The shape and dimensions of a filter (e.g., characteristics such as channel wall thickness and porosity) can vary depending on the intended application of the filter. A filter can be configured for use with an internal combustion engine to filter exhaust gases emitted by that engine. The internal combustion engine can be a gasoline spark-ignition engine. However, when configured for use with an internal combustion engine in the form of a diesel or gasoline engine, the filter has a specific application.

[0055] In this specification, the terms "inlet" and "outlet" refer to the orientation of the porous substrate when subjected to a gas flow generated by a vacuum generator, wherein the gas flow is from the inlet face or inlet end toward the outlet face or outlet end. It should be understood that the porous substrate may employ other orientations in subsequent processing steps or applications, such as when used in vehicles to treat exhaust gases. For example, the exhaust gas flow through the porous substrate during use may be from the "inlet" to the "outlet," or vice versa.

[0056] In this specification, the term "vacuum generator" refers to a device or combination of devices used to generate a reduced pressure. Non-limiting examples of suitable devices include vacuum generators operating according to the Venturi principle, vacuum pumps such as rotary vane and liquid ring vacuum pumps, and regenerative blowers.

[0057] In this specification, the term "controller" can refer to a function that may include hardware and / or software. A controller may include a control unit or a computer program that runs on dedicated or shared computing resources. A controller may include a single unit or may consist of multiple subunits operatively connected. A controller may reside on a single processing resource or may be distributed across spatially separated processing resources. A controller may include a microcontroller, one or more processors (such as one or more microprocessors), memory, configurable logic, firmware, etc. Attached Figure Description

[0058] Aspects and embodiments of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0059] Figure 1 This is a schematic diagram of the device according to this disclosure;

[0060] Figure 2 yes Figure 1 A schematic diagram of the annular air blades and the inlet surface of the porous substrate of the device;

[0061] Figure 3 From Figure 2 A schematic diagram of the side of the annular air blade and the porous substrate;

[0062] Figure 4 This is a photograph of the inlet surface of the porous substrate after the dry powder coating has been applied; and

[0063] Figure 5 After the operation of the annular air blades Figure 4 Photographs of porous substrates. Detailed Implementation

[0064] Readers in the art will recognize that, unless the present context otherwise teaches, one or more features of one aspect or embodiment of this disclosure may be combined with one or more features of any other aspect or embodiment of this disclosure.

[0065] Now refer to Figure 1 The illustration describes an example of an apparatus according to the present disclosure, showing a schematic diagram of an apparatus 1 for processing a porous substrate 10 for filtering particulate matter from exhaust gas. The porous substrate 10 is of the type having an inlet surface 11 and an outlet surface 12, which are separated by a porous structure 13.

[0066] The device 1 includes: a retainer 2 for holding a porous substrate 10; an inlet chamber 15 communicating with an inlet surface 11; a vacuum generator communicating with an outlet surface 12 and for establishing a gas flow from the inlet surface 11 to the outlet surface 12 through the porous substrate 10; a spraying device for spraying dry powder into or within the inlet chamber 15; and an annular air vane 30.

[0067] The retainer 2 may include means for securely holding the porous substrate 10. The retainer 2 may include an upper inflatable collar 3 supplied by an inflation line 5 and a lower inflatable collar 4 supplied by an inflation line 6.

[0068] The vacuum generator may include a vacuum cone 17 connected via a line 16 to, for example, a regenerative blower.

[0069] The spraying apparatus may include a nozzle 20, which supplies dry powder, for example, by gravity supply along a powder supply line 21. A gas feed line 22 may supply compressed gas (e.g., compressed air) to the nozzle 20 for entraining, moving, and expelling the dry powder from the nozzle 20. The nozzle 20 may be as follows: Figure 1 The powder is located inside the entrance chamber 15, or alternatively outside the entrance chamber 15, but is oriented to spray dry powder into the entrance chamber 15.

[0070] The nozzle 20 can be positioned at a height h above the plane of the inlet surface 11 of the porous substrate 10. The height h can be 50cm to 250cm, optionally 50cm to 200cm, optionally 100cm to 200cm, optionally 150cm to 200cm, or optionally 200cm.

[0071] The entrance chamber 15 may include a pipe 15, which optionally has an open upper end. The pipe 15 may have a shape conforming to the shape of the entrance surface 11 and a size equal to or greater than that of the entrance surface 11.

[0072] Annular air blades 30 can be like Figure 1 The annular air vane 30 is located within the inlet chamber 15, or may be arranged in series with one or more portions of the inlet chamber 15, or is located between the inlet chamber 15 and the inlet surface 11. The gas supply source 31 supplies pressurized gas (e.g., air) to the annular air vane 30.

[0073] like Figure 2 and Figure 3 As shown, the annular air blade 30 may include two semi-circular elements 32 and 33, which together form an annulus extending 360° around the inlet surface 11 of the porous substrate 10. Each semi-circular element 32 and 33 may have its own gas inlet 31a and 31b, which can be supplied from a common gas supply source 31.

[0074] The annular air blade 30 may have a gas outlet 35 that extends around the inner peripheral wall of each semicircular element 32, 33 and is as follows: Figure 3 As shown, it is oriented approximately radially inward. Therefore, as... Figure 2 As indicated by the arrows, the gas entering each semicircular element 32, 33 is guided around its element 32, 33 and exits approximately radially, such that the gas is emitted around all or substantially all 360° of the annular air blade 30.

[0075] The lower surface 36 of the gas outlet 35 can be circular so that, due to the Coanda effect, the gas leaving the gas outlet 35 is deflected downwards toward the inlet surface 11, such as... Figure 3 As shown. Therefore, a roughly conical airflow can be obtained.

[0076] The plane of the gas outlet 35 of the annular air blade 30 can be positioned between 1 cm and 10 cm above the plane of the inlet surface 11, such as... Figure 3 The figure is schematically illustrated using the reference numeral d.

[0077] In use, the porous substrate 10 is initially positioned in the retainer 2, such that the inlet surface 11 communicates with the inlet chamber 15 and the outlet surface 12 communicates with the vacuum generator (e.g., vacuum cone 17). The upper inflatable collar 3 and the lower inflatable collar 4 can be inflated to secure the porous substrate 10.

[0078] Next, by using a vacuum generator to apply pressure to the outlet surface 12 of the porous substrate 10, a gas flow from the inlet surface 11 to the outlet surface 12 through the porous substrate 10 is established.

[0079] For example, dry powder is sprayed into the inlet chamber 15 using nozzle 20 or sprayed into the inlet chamber, such that the dry powder is entrained in the gas flow and passes through the inlet surface 11 of the porous substrate 10 to contact the porous structure. Example

[0080] like Figure 4 As shown, this process can lead to the accumulation of dry powder on the inlet face 11, particularly on the ends of the walls that separate the inlet channels and / or on any channels that are blocked at their inlet ends.

[0081] Therefore, the annular air vane 30 can be activated to direct the gas flow downwards onto the inlet face 11 to blow away the dry powder accumulated on the inlet face 11 of the porous substrate 10. The vacuum generator can remain active during the activation of the annular air vane 30, such that the dry powder blown away from the inlet face 11 is entrained in the gas flow and passes through the inlet face 11 of the porous substrate 10.

[0082] like Figure 5 As shown, the result is that the accumulation of dry powder can be effectively removed from the inlet surface 11.

[0083] After the application of dry powder into or into the inlet chamber 15 has been stopped (but the vacuum generator is still running), the annular air vane 30 may be activated to blow away the dry powder. Alternatively or additionally, the annular air vane 30 may be activated during the application of dry powder into or into the inlet chamber 15.

[0084] Gas can be supplied to the annular air vane 30 at pressures up to 8 bar, optionally at 3 to 8 bar, optionally at 3 to 6 bar, optionally at 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, 7 bar, or 8 bar. The annular air vane 30 can emit gas at a flow rate greater than 150 liters / minute, optionally greater than 200 liters / minute, optionally greater than 250 liters / minute.

Claims

1. A method of applying a dry powder to a porous substrate, the porous substrate having an inlet face and an outlet face, wherein the inlet face and the outlet face are separated by a porous structure, the method comprising the steps of: a) positioning the porous substrate in a holder such that the inlet face is in communication with an inlet chamber and the outlet face is in communication with a vacuum generator; b) establishing a flow of gas through the porous substrate from the inlet face to the outlet face by applying a reduced pressure to the outlet face of the porous substrate using the vacuum generator; c) spraying the dry powder into or within the inlet chamber such that the dry powder is entrained in the flow of gas and passes through the inlet face of the porous substrate to contact the porous structure; and d) activating a ring air blade to blow off dry powder accumulated on the inlet face of the porous substrate, wherein the vacuum generator remains active during activation of the ring air blade such that the dry powder blown off from the inlet face is entrained in the flow of gas and passes through the inlet face of the porous substrate.

2. The method of claim 1, wherein the ring air blade is activated to blow off the dry powder after spraying of the dry powder into or within the inlet chamber has ceased.

3. The method of claim 1 or claim 2, wherein the ring air blade is activated during spraying of the dry powder into or within the inlet chamber.

4. The method of any preceding claim, wherein the ring air blade is oriented to direct a flow of gas at a downward angle onto the inlet face of the porous substrate.

5. The method of any preceding claim, wherein the ring air blade emits a 360° or substantially 360° flow of gas.

6. The method of any preceding claim, wherein a plane of a gas outlet of the ring air blade is positioned between 1 cm and 10 cm above a plane of the inlet face.

7. The method of any preceding claim, wherein the ring air blade is located within the inlet chamber or between the inlet chamber and the inlet face of the porous substrate.

8. The method of any preceding claim, wherein the ring air blade is supplied with gas at a pressure of up to 8 bar, optionally at a pressure of 3 to 8 bar, optionally at a pressure of 3 to 6 bar, optionally at a pressure of 1, 2, 3, 4, 5, 6, 7 or 8 bar.

9. The method of any preceding claim, wherein the ring air blade emits gas at a flow rate of greater than 150 litres / minute, optionally greater than 200 litres / minute, optionally greater than 250 litres / minute.

10. The method of any preceding claim, wherein the dry powder is sprayed into or within the inlet chamber using a spraying device, optionally a nozzle. ​ ​ ​ ​ 11. The method according to claim 10, wherein the spraying device is located at a distance of 50 cm to 250 cm from the inlet face, optionally at a distance of 50 cm to 200 cm from the inlet face, optionally at a distance of 100 cm to 200 cm from the inlet face, optionally at a distance of 150 cm to 200 cm from the inlet face, optionally at a distance of 200 cm from the inlet face.

12. An apparatus for applying a dry powder to a porous substrate having an inlet face and an outlet face, wherein the inlet face and the outlet face are separated by a porous structure, the apparatus comprising: a) a holder for holding the porous substrate; b) an inlet chamber in communication with the inlet face; c) a vacuum generator in communication with the outlet face and for establishing a gas flow through the porous substrate from the inlet face to the outlet face; d) a spraying device for spraying the dry powder into or within the inlet chamber; and e) an annular air blade.

13. The apparatus according to claim 12, wherein the annular air blade is oriented to direct a gas flow at a downward angle onto the inlet face of the porous substrate when the porous substrate is located in the holder to blow off dry powder that can accumulate on the inlet face of the porous substrate.

14. The apparatus according to claim 12 or claim 13, wherein the annular air blade is configured to emit a gas flow of 360° or substantially 360°.

15. The apparatus according to claim 12 or claim 14, wherein a plane of a gas outlet of the annular air blade is positioned between 1 cm and 10 cm above a plane of the inlet face.

16. The apparatus according to any one of claims 12 to 15, wherein the annular air blade is located within the inlet chamber or between the inlet chamber and the inlet face of the porous substrate.

17. The apparatus according to any one of claims 12 to 16, wherein the spraying device comprises a nozzle.

18. The apparatus according to any one of claims 12 to 17, wherein the spraying device is located at a distance of 50 cm to 250 cm from the inlet face, optionally at a distance of 50 cm to 200 cm, optionally at a distance of 100 cm to 200 cm, optionally at a distance of 150 cm to 200 cm, optionally at a distance of 200 cm.

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