Powder spray nozzles and corresponding method

Abstract

A powder spray nozzle (1) comprising: a powder inlet (2) configured to receive powder from a source of powder; a powder outlet (3) having an outlet orifice (4) configured to spray powder out of the powder spray nozzle (1); a first conduit (5) extending between the powder inlet (2) and the powder outlet (3); and an unclogging member (6) configured to be movable between a retracted position wherein the unclogging member (6) is held clear of the outlet orifice and a projected position wherein a distal end of the unclogging member (6) is projected at least partially into the outlet orifice (4).

Description

[0001] POWDER SPRAY NOZZLES AND CORRESPONDING METHOD

[0002] The present disclosure relates to improvements in powder spray nozzles. In particular it relates to a powder spray nozzle, a powder spraying system comprising the powder spray nozzle and a method of operating a powder spray nozzle. In some example embodiments the powder spray nozzle, powder spray system and method find application in the coating of porous substrates having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure. The porous substrates may be, for example, a flow-through substrate or a filter, for example for an emissions control device of an internal combustion engine.

[0003] Background to the Disclosure

[0004] WO2021028691 A1 (which is hereby incorporated by reference in its entirety) describes a method for treating a filter for filtering particulate matter from exhaust gas, the method comprising the steps of: a) containing a dry powder in a reservoir; b) locating a filter in a filter holder, the filter comprising a porous substrate having an inlet face and an outlet face, the inlet face and the outlet face being separated by a porous structure; c) establishing a primary 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 spray device located upstream of the inlet face of the filter; and e) spraying the dry powder, using the spray device, towards the inlet face of the filter such that the dry powder is entrained in the primary gas flow and passes through the inlet face of the filter to contact the porous structure.

[0005] While the methods and apparatus of WO2021028691 A1 have been found to be effective in producing improved filters there is still a desire to improve the methods and apparatus, in particular in the handling and spraying of powders, in particular dry powders.

[0006] Summary of the Disclosure

[0007] In a first aspect the present disclosure provides a powder spray nozzle comprising: a powder inlet configured to receive powder from a source of powder; a powder outlet having an outlet orifice configured to spray powder out of the powder spray nozzle; a first conduit extending between the powder inlet and the powder outlet; and an unclogging member configured to be movable between a retracted position in which the unclogging member is held clear of the outlet orifice and a projected position in which a distal end of the unclogging member is projected at least partially into the outlet orifice.

[0008] The powder spray nozzle provides improved handling and spraying of powders. In particular, the provision of the unclogging member allows for the intermittent clearing of powder that may accumulate in outlet orifice during spraying. This has been found to be of particular use when spraying powders that are especially sticky and / or cohesive - cohesive either to itself or to metal surfaces the powder may come into contact with. The unclogging member provides a convenient and quick way of effecting the clearing of the outlet orifice. By incorporating the unclogging member as part of the powder spray nozzle the requirement for additional .separate tools is avoided.

[0009] In some embodiments the unclogging member is a rod. In some embodiments the rod is a straight elongate member. In some embodiments the unclogging member, e.g. rod, has a cross-sectional shape that matches the shape of the outlet orifice, for example a round cross-sectional shape and a circular outlet orifice. In some embodiments the unclogging member, e.g. rod, is a solid rod. In some embodiments the unclogging member, e.g. rod, has a tapered, pointed or rounded distal end. In some embodiments the rod is a metal rod, for example formed from stainless steel. In some embodiments the unclogging member may be a slim, needle-like rod. In some embodiments the rod may have an external diameter of 0.5 to 5.0 mm, optionally 1.0 to 2.5 mm, optionally 1.0 to 2.0 mm, optionally 1.5 to 1.6 mm.

[0010] The amount of movement of the unclogging member between its retracted and projected positions may be varied as necessary dependent on the design and dimensions of the powder spray nozzle. In some embodiments, for example, the unclogging member is moved a distance of 5 to 40 mm between its retracted and projected positions.

[0011] The unclogging member may extend within the first conduit and in the retracted position the distal end of the unclogging member may be located within the first conduit. In this way the unclogging member may be largely retained within an interior of the powder spray nozzle. Locating the distal end of the unclogging member in the first conduit reduces the risk of a user contacting the unclogging member during spraying, reducing the chance of injury.

[0012] In some embodiments the powder spray nozzle further comprises an actuator coupled to the unclogging member for moving the unclogging member from the projected position to the retracted position and / or from the retracted position to the projected position. The actuator permits a powered operation of the clearing of the outlet orifice, for example under computer control. In some embodiments the actuator comprises a pneumatic cylinder. Use of a pneumatic cylinder provides a convenient operation of the unclogging member and allows for fast movement of the unclogging member between the retracted position and the projected position.

[0013] The pneumatic cylinder may be housed in a housing separate from a nozzle body of the powder spray nozzle. In this way the workings of the pneumatic cylinder may be kept isolated from the powder passing through the first conduit. For example, only the unclogging member may be exposed to the first conduit with the pneumatic cylinder being outside a nozzle body of the powder spray nozzle. In some embodiments the unclogging member, e.g. a rod, extends through an exterior wall of a nozzle body of the powder spray nozzle. One or more seal members may be provided at an interface between the unclogging member and the nozzle body to reduce or prevent leakage of powder from the first conduit.

[0014] In some embodiments the powder spray nozzle further comprises a spring force member for moving the unclogging member from the retracted position to the projected position and / or from the projected position to the retracted position. In alternative embodiments another source of motive force may be used, for example, an hydraulic actuator or electromagnetic solenoid.

[0015] In some embodiments the pneumatic cylinder (or other powered source of motive force) may be used to move the unclogging member from the projected position into the retracted position and the spring force member may be used to move the unclogging member in the opposite direction from the retracted position into the projected position. In this way the force of the spring force member (which will generally be less than that imparted by the pneumatic cylinder) may be used to move the unclogging member into a potentially exposed position, thus reducing the likelihood of any spiking injury of a user handling the powder spray nozzle. In particular, the spring force of the spring force member may be chosen to be at a suitable level.

[0016] While projecting the unclogging member at least partially into the outlet orifice can be used to clear accumulated powder from the outlet orifice, in some embodiments it may be preferred that in the projected position the unclogging member is projected fully into the outlet orifice, and optionally is projected into and through the outlet orifice. In this way, a better clearing of the accumulated powder may be achieved.

[0017] In some embodiments in the projected position an annular clearance is provided between the unclogging member and a body of the powder spray nozzle such that the outlet orifice is not sealed in a fluid-tight manner. In some embodiments, the annular clearance may have a width of 0.05 mm to 0.4 mm, optionally 0.1 mm to 0.2 mm. For example the unclogging member may have an external diameter of 1.6 mm and the outlet orifice may have an internal diameter of 2.0 mm, giving an annular clearance width of 0.2 mm.

[0018] In some embodiments the powder spray nozzle further comprises a second conduit for gas, the second conduit extending between a gas inlet and a gas outlet, the gas outlet being located in proximity to the powder outlet such that a gas flowing through the second conduit and out of the gas outlet produces a suction force at the outlet orifice of the powder outlet to promote flow of the powder through the first conduit and out of the outlet orifice.

[0019] The provision of a suction force at the powder outlet may improve the dispersion and mixing of the particles of the powder in a carrier gas into which the powder is sprayed. For example, the powder spray nozzle may impart increased shear forces and / or an increased pressure drop on the powder as it passes through the powder spray nozzle. This may beneficially act to de-agglomerate the powder, for example where the particles of the dry have a tendency to form cohesive agglomerates.

[0020] Additionally, the provision of a suction force at the powder outlet to promote flow of the powder through the first conduit and out of the powder outlet and the nozzle outlet may beneficially help to enable the feeding of the powder into the powder spray nozzle by gravity. For example, using a suction force at the powder outlet promotes flow of the powder through the first conduit and out of the powder outlet and the nozzle outlet. This means that the powder spray nozzle does not necessarily require to be fed with a mixture of gas (e.g. compressed air) and powder into the first conduit in order to convey the powder to and through the powder spray nozzle. Rather, the powder spray nozzle may be fed with the powder from a source of powder (or at least the part of the source of powder that communicates with the supply conduit) through the supply conduit without the use of a gas stream, e.g. the powder does not need to be entrained in a gas stream as is passes along the supply conduit but rather moves along the supply conduit under the action of gravity assisted by the suction force generated in the powder spray nozzle. This may permit the flow of the powder to be more precisely controlled and the dispersion of the powder into the carrier gas to be more homogenous. Additionally, the powder may be sprayed less energetically if desired.

[0021] The powder outlet and the gas outlet may be orientated to promote mixing of the gas with the powder.

[0022] In some embodiments the powder outlet is located within the nozzle body upstream of the nozzle outlet such that an initial mixing of the gas with the powder occurs within an interior of the nozzle body upstream of the nozzle outlet.

[0023] In other embodiments the powder outlet is located at or near the nozzle outlet of the nozzle body such that an initial mixing of the gas with the powder occurs outside of the nozzle body.

[0024] In some embodiments the gas outlet is located at or near the nozzle outlet of the nozzle body.

[0025] In some embodiments the gas outlet comprises an annular outlet that surrounds the powder outlet.

[0026] In some embodiments the powder outlet is centrally located on a longitudinal axis of the nozzle body.

[0027] In some embodiments the powder outlet comprises a single powder aperture.

[0028] In some embodiments the powder inlet, powder outlet, and the first conduit are comprised in a nozzle body of the powder spray nozzle.

[0029] In some embodiments the nozzle body comprises a tubular element defining at least the powder outlet of the first conduit and a cap element, wherein a clearance between the tubular element and the cap element defines the gas outlet.

[0030] In some embodiments the clearance between the tubular element and the cap element is 0.2 to 2.0 mm, optionally 0.2 to 1.0 mm, optionally 0.25 to 0.9 mm, optionally 0.6 mm. In some embodiments the first conduit comprises a bore whose internal diameter decreases from a first diameter at the powder inlet to a second diameter at or adjacent the powder outlet. In some embodiments the first conduit comprises a bore whose internal diameter smoothly decreases from a first diameter at the powder inlet to a second diameter at or adjacent the powder outlet. In some embodiments the first conduit comprises a bore whose internal diameter decreases from a first diameter at the powder inlet to a second diameter at or adjacent the powder outlet exclusively via one or more tapered sections. In these ways, the movement of the powder along the first conduit under gravity may be promoted.

[0031] In a second aspect the present disclosure provides a powder spraying system comprising: a) a source of dry powder; b) a powder spray nozzle of the first aspect; and c) a supply conduit connecting the source of dry powder with the powder inlet of the powder spray nozzle.

[0032] In a third aspect the present disclosure provides a method of operating a powder spray nozzle comprising the steps of: receiving powder from a source of powder into a powder inlet of the powder spray nozzle; conveying the powder along a first conduit to a powder outlet of the powder spray nozzle and spraying the powder out of the powder spray nozzle through an outlet orifice; and intermittently clearing accumulated powder from the outlet orifice by using an unclogging member of the powder spray nozzle wherein the unclogging member is moved from a retracted position in which the unclogging member is held clear of the outlet orifice into a projected position in which a distal end of the unclogging member is projected at least partially into the outlet orifice to dislodge accumulated powder from the outlet orifice.

[0033] In some embodiments after each clearing the unclogging member is retracted into the retracted position. In this way the outlet orifice is left unimpeded for further spraying of powder.

[0034] In some embodiments movement of the unclogging member is effected by an actuator, optionally a pneumatic cylinder, hydraulic actuator or electromagnetic solenoid. In some embodiments the intermittent clearing is performed in between spraying operations. In other embodiments the intermittent clearing is performed during a spraying operation. In some embodiments the intermittent clearing is carried out at a pre-determined frequency during spraying. Alternatively, the intermittent clearing may be performed on detection of an accumulation of powder in the outlet orifice.

[0035] The powder spraying system and the powder spray nozzle may find particular application when used in a method of treatment of a porous substrate. The method of treatment of the porous substrate may comprise the steps of: a) containing the powder in the source of powder, for example in a reservoir; b) locating a porous substrate in a substrate holder, the porous substrate having an inlet face and an outlet face, the inlet face and the outlet face being separated by a porous structure; c) establishing a primary gas flow through the porous structure by applying a pressure reduction to the outlet face of the porous substrate; d) transferring the powder from the source of powder through the supply conduit to the powder spray nozzle that is located upstream of the inlet face of the porous substrate; and e) spraying the powder, using the powder spray nozzle, towards the inlet face of the porous substrate such that the powder is entrained in the primary gas flow and passes through the inlet face to contact the porous structure.

[0036] The powder spraying system and / or the powder spray nozzle as described above may be incorporated as part of an apparatus for treating a porous substrate. The apparatus may further comprise a substrate holder for holding the porous substrate, wherein the nozzle outlet of the powder spray nozzle is orientated to spray the powder towards an inlet face of the porous substrate. The apparatus may further comprise a vacuum generator in communication with an outlet face of the porous substrate for generating a primary flow of gas through the porous substrate, wherein the powder spray nozzle is located upstream of the inlet face of the porous substrate and is orientated to spray the powder into the primary flow of gas upstream of the inlet face of the porous substrate. The apparatus may further comprise a flow conduit upstream of the inlet face for channelling the primary flow of gas towards the inlet face of the porous substrate.

[0037] In some embodiments the powder comprises or consists of dry powder. In this specification the term “dry powder” refers to a particulate composition that is not suspended or dissolved in a liquid. It is not meant to necessarily imply a complete absence of all water molecules. In some embodiments the dry powder is free-flowing.

[0038] In some embodiments the dry powder comprises or consists of a silicone resin. Silicone resins are known and are branched, cagelike oligosiloxanes and polysiloxanes. The branching in silicone resins results from the presence of so called “T” and / or “Q” units in the resin which refer to RSiCh and SiC units (R is an alkyl or aryl group), respectively, wherein further silicon units are bonded to the oxygen atoms. “M” units, i.e. , RsSiO unit are terminal units wherein the oxygen atom provides a link to the resin backbone. Similarly, “D” units, i.e., R2SiC>2 units provide linear connectivity across the two oxygen atoms. One well known nonbranched and linear polysiloxane is polydimethylsiloxane (PDMS; i.e., (Me2SiO)n).

[0039] Preferably, the silicone resin is a solid at room temperature (e.g., about 25°C). Accordingly, the silicone resin preferably has a melting point of greater than 25°C, preferably greater than 30°C, more preferably greater than 35°C. Preferably, the melting point of the silicone resin is less than 100°C, preferably less than 95°C, less than 90°C, less than 85°C or less than 80°C. Non-branched polysiloxanes such as PDMS typically have lower melting points than silicone resins which are branched. For example, the melting point of PDMS is about - 40°C. WO 2011 / 151711 discloses binding powder in place by treatment with polydimethylsiloxane which forms silica when hydrolysed at sufficiently high temperature.

[0040] Similarly, it may be preferable that the silicone resin has a glass transition temperature (Tg) of greater than 30°C, preferably greater than 35°C, and / or less than 100°C, preferably less than 80°C. Without wishing to be bound by theory, it is believed that silicone resins which have such melting points and / or glass transition temperatures are particularly suited for the powder coating process, i.e., for effective particulate dispersion across the porous substrate, yet low enough to permit low temperature calcination thereby effectively and efficiently adhering inorganic particles to gas contacting surfaces of the channel walls of the porous substrate.

[0041] Preferably, the silicone resin has a molecular weight of greater than 1 ,000, preferably greater than 2,000, preferably greater than 5,000, preferably greater than 10,000, and / or a molecular weight of less than 500,000, preferably less than 200,000.

[0042] As used herein, molecular weight refers to the weight average molecular weight (Mw) which may be measured using any conventional means in the art. In some embodiments, the molecular weight may be relatively low since the hydrogen bonding provided by hydroxy functionalities provides the silicone resin with a sufficiently high melting point and / or glass transition temperature. Accordingly, in some embodiments the molecular weight of the silicon resin may be from 1,000 to 10,000, preferably from 1 ,000 to 5,000, preferably from 1 ,200 to 3,500, such as from 1 ,500 to 2,000. Silicone resins having molecular weights below 1,000 are less preferred since they are typically either liquid and not suitable for dry spraying or do not have as much branching as larger molecules which is believed to provide enhanced binding of the inorganic particles to the porous substrate.

[0043] Nevertheless, the molecular weight of the silicone resin may preferably be from 15,000 to 150,000, preferably from 20,000 to 120,000, preferably from 60,000 to 100,000. Some preferable resins have an Mwof from 8,000 to 15,000, some from 20,000 to 60,000 and others from 80,000 to 120,000.

[0044] It is particularly preferred that the silicone resin has the formula [RxSiXyOz]n, wherein R is an alkyl or aryl group, X is a functional group bonded to silicon, and wherein z is more than 1 and less than 2. As will be appreciated, n is large so as to provide an oligomer or polymer necessary for a silicone resin, particularly a resin which is solid at room temperature. Whilst dependent on the molecular mass of the R and X groups, an Mw of greater than 1,000 may be achieved where n is greater than 10, an Mw of greater than 10,000 may be achieved where n is greater than 100 and an Mw of greater than 100,000 may be achieved where n is greater than 1,000. Accordingly, n may preferably be greater than 10, greater than 100, greater than 1 ,000.

[0045] As will be appreciated, R is an alkyl or an aryl bonded to silicon and X is a nonhydrocarbon functional group bonded to silicon. Equally, since silicon is a tetravalent atom, it will be appreciated that x + y + 2z = 4. z is less than 2 since where z = 2, x and y = 0 providing silica (i.e., silicon dioxide; (SiC>2)n). Similarly, z is greater than 1 since where z = 1 , x + y = 2 providing a substituted polysiloxane (e.g. (RXSiO)n) consisting of “D” units providing a linear resin (e.g. -O-(SiRX)-O-(SiRX)-O-). One example is polydimethylsiloxane. Accordingly, O refers to oxygen bridging two silicon atoms in the polymeric backbone of the silicone resin.

[0046] Preferably, 0 < x + y < 2, preferably 0 < x + y < 1.5, preferably 0 < x + y < 1. Preferably, x, y and / or x + y is greater than 0.1 , preferably greater than 0.2. In one preferred embodiment, x + y is 1 providing a silicone resin known generally as a 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 where the polysilsesquioxane is a polyalkylsilsesquioxane such as polymethylsilsesquioxane (MeSiC>3 / 2)n.

[0047] Typically, where present, X is one or more of H, hydroxy (OH), Cl and Ci-Ce alkoxy, preferably one or more of OH and Ci-Ce alkoxy, preferably wherein the Ci-Ce alkoxy is 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 aminyl (NH2, NR2), epoxy, acrylate, and vinyl, though these are less preferred since the presence of hydroxy or alkoxy groups is believed to provide more effective cross-linking during calcination. As described above, any oxygen present in the terminal functional group does not contribute to “Oz” in the above formula which refers to silicon bridging oxygen atoms.

[0048] In some embodiments the dry powder may comprise or consist of a zeolite. Zeolites are structures formed from alumina and silica and the SAR determines the reactive sites within the zeolite structure. The zeolite may be a small pore zeolite (e.g. a zeolite having a maximum ring size of eight tetrahedral atoms), a medium pore zeolite (e.g. a zeolite having a maximum ring size of ten tetrahedral atoms) or a large pore zeolite (e.g. a zeolite having a maximum ring size of twelve tetrahedral atoms) or a combination of two or more thereof.

[0049] Examples of suitable zeolites include silicate zeolite, aluminosilicate zeolite, metal- substituted aluminosilicate zeolite, AIPO, MeAIPO, SAPO, MeAPSO, and the like. In some embodiments, the zeolites are selected from aluminosilicate, borosilicate, gallosilicate, SAPO, AIPO, MeAPSO, and MeAPO zeolites.

[0050] When the zeolite is a small pore zeolite, then the small pore zeolite may have a framework structure represented by a Framework Type Code (FTC) selected from the group comprising (e.g. 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 a mixture and / or combination and / or an intergrowth of two or more thereof. In some embodiments, the small pore zeolite has a framework structure selected from the group comprising (e.g. consisting of) CHA, LEV, AEI, AFX, ERI, LTA, SFW, KFI, DDR and ITE. In some embodiments, the small pore zeolite has a framework structure selected from the group comprising (e.g. consisting of) CHA and AEI. The small pore zeolite may have a CHA framework structure.

[0051] When the zeolite is a medium pore zeolite, then the medium pore zeolite may have a framework structure represented by a Framework Type Code (FTC) selected from the group comprising (e.g. consisting of) 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 and / or an intergrowth of two or more thereof. In some embodiments, the medium pore zeolite has a framework structure selected from the group comprising (e.g. consisting of) FER, MEL, MFI, and STT. In some embodiments, the medium pore zeolite has a framework structure selected from the group comprising (e.g. consisting of) FER and MFI, particularly MFI. When the medium pore molecular sieve has a FER or MFI framework, then the zeolite may be ferrierite, silicalite or ZSM-5.

[0052] When the zeolite is a large pore zeolite, then the large pore zeolite may have a framework structure represented by a Framework Type Code (FTC) selected from the group comprising (e.g. consisting of) 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 a mixture and / or an intergrowth of two or more thereof. In some embodiments, the large pore zeolite has a framework structure selected from the group comprising (e.g. consisting of) AFI, BEA, MAZ, MOR, and OFF. In some embodiments, the large pore zeolite has a framework structure selected from the group comprising (e.g. consisting of) BEA, MOR and FAU. When the large pore molecular has a framework structure of FTC BEA, FAU or MOR, then the zeolite may be a beta zeolite, faujasite, zeolite Y, zeolite X or mordenite.

[0053] In some embodiments, the zeolite has a framework type selected from 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, CFI, 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, MTT, 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, Wl, VNI, VSV, WIE, WEN, YUG, ZON, or combinations thereof. In some embodiments, the zeolite has a framework type selected from 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.

[0054] In another embodiment, the dry powder comprises or consists of refractory oxide particles which can be based on an oxide selected from the group consisting of alumina, silica, zirconia, ceria, chromia, magnesia, calcia, titania and mixed oxides of any two or more thereof. Preferably, the refractory oxide particles comprise calcium aluminate, fumed alumina, fumed silica, fumed titania, fumed zirconia, fumed ceria, alumina aerogel, silica aerogel, titania aerogel, zirconia aerogel, ceria aerogel or a mixture thereof. The one or more fumed refractory powders (refractory oxide particles) may be produced by a pyrogenic process, for example flame pyrolysis.

[0055] In some embodiments the dry powder comprises or consists of a metal compound for forming by thermal decomposition a metal oxide. The dry powder may consist of a single metal compound of may consist of a mixture or blend or successive doses of two or more metal compounds. The or each metal compound may contain one or more metal cations. Where a plurality of metal cations is present these may be of the same or of different metals. The metal compound may comprise or consist of a metal hydroxide, a metal phosphate, a metal carbonate, a metal sulphate, a metal perchlorate, a metal iodide, a metal oxalate, a metal acetate, a metal chlorate or a mixture thereof. The metal of the metal compound may comprise or consist of one or more of magnesium, calcium, strontium, barium, aluminium, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium. The dry powder may additionally comprise a metal oxide or mixed metal oxide. Optionally the dry powder comprises 90 wt% or greater of the metal compound for forming by thermal decomposition a metal oxide and 10 wt% or less of the metal oxide or mixed metal oxide. Optionally the dry powder comprises 95 wt% or greater of the metal compound for forming by thermal decomposition a metal oxide and 5 wt% or less of the metal oxide or mixed metal oxide. Optionally the dry powder comprises 99 wt% or greater of the metal compound for forming by thermal decomposition a metal oxide and 1 wt% or less of the metal oxide or mixed metal oxide. The metal of the metal oxide or mixed metal oxide may comprise or consist of one or more of aluminium, magnesium, calcium, strontium, barium, aluminium, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium. Optionally the dry powder comprises or consists of a metal hydroxide, a metal phosphate, a metal carbonate or a mixture thereof. The metal hydroxide may be selected from the group consisting of magnesium hydroxide, calcium hydroxide, strontium hydroxide and barium hydroxide. The metal phosphate may be selected from the group consisting of magnesium phosphate, calcium phosphate, strontium phosphate and barium phosphate. The metal carbonate may be selected from the group consisting of magnesium carbonate, calcium carbonate, strontium carbonate and barium carbonate.

[0056] The dry powder may consist of a single powder type or a mixture of powder types. For example the dry powder may comprise or consist of a mixture of zeolite and silicone resin.

[0057] In this specification the expression that a powder “consists of’ means a powder that essentially consists of only the specified constituent(s), other than for unavoidable impurities as normally encountered as will be recognised by the person skilled in the art.

[0058] The porous substrate can be a ceramic substrate or a metallic substrate. The ceramic substrate may be made of any suitable refractory material, e.g., alumina, silica, titania, ceria, zirconia, magnesia, zeolites, silicon nitride, silicon carbide, zirconium silicates, magnesium silicates, aluminosilicates, metalloaluminosilicates (such as cordierite and spudomene), or a mixture or mixed oxide of any two or more thereof. The metallic substrate may be made of any suitable metal, and in particular heat-resistant metals and metal alloys such as titanium and stainless steel as well as ferritic alloys containing iron, nickel, chromium, and / or aluminum in addition to other trace metals.

[0059] The porous substrate may be a flow-through substrate, e.g., a flow-through monolith having a honeycomb structure with many small, parallel thin-walled channels running axially through the porous substrate and extending throughout from an inlet end to an outlet end of the porous substrate.

[0060] The porous substrate can be a filter. The filter may be a wall-flow filter having, for example, a monolith filter substrate. The channels of a wall-flow filter are alternately blocked, which allow the exhaust gas stream to enter a channel from the inlet, then flow through the channel walls, and exit the filter from a different channel leading to the outlet.

[0061] The filter may be a "bare" filter or alternatively may be one with an incorporated catalytic function ability such as oxidation, NOx-trapping, or selective catalytic reduction activity. The porous substrate may comprise a composition (known as a washcoat) that coats the porous structure of the filter. The washcoat may be a catalytic washcoat. The catalytic washcoat may comprise a catalyst, selected from the group consisting of a hydrocarbon trap, a three-way catalyst (TWC), a NOx absorber, an oxidation catalyst, a selective catalytic reduction (SCR) catalyst, a lean NOx catalyst and combinations of any two or more thereof. The catalyst, for example the TWC, NOx absorber, oxidation catalyst, hydrocarbon trap and the lean NOx catalyst, may contain one or more platinum group metals, particularly those selected from the group consisting of platinum, palladium and rhodium.

[0062] Consequently, the coated filter may, for example, be a catalysed soot filter (CSF), a selective catalytic reduction filter (SCRF), a lean NOx trap filter (LNTF), a gasoline particulate filter (GPF), an ammonia slip catalyst filter (ASCF) or a combination of two or more thereof (e.g. a filter comprising a selective catalytic reduction (SCR) catalyst and an ammonia slip catalyst (ASC).

[0063] The shape and dimensions of the filter, for example properties such as the channel wall thickness and its porosity etc. may be varied depending on the intended application for the filter. The filter may be configured for use with an internal combustion engine to filter the exhaust gas emitted by the internal combustion engine. The internal combustion engine may be a gasoline spark ignition engine. However, the filter finds particular application when configured for use with an internal combustion engine in the form of a diesel or gasoline engine.

[0064] In this specification the term “vacuum generator” refers to an apparatus or combination of apparatus that function to produce a pressure reduction. Non-limiting examples of suitable apparatus include vacuum generators that operate on the venturi principle, vacuum pumps, for example rotary vane and liquid ring vacuum pumps, and regenerative blowers.

[0065] Brief Description of the Drawings Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0066] Figure 1 is a schematic diagram of a powder spray nozzle according to the present disclosure;

[0067] Figure 2 is a cross-sectional view of a powder spray nozzle according to the present disclosure with its unclogging member in a retracted position;

[0068] Figure 3 is another cross-sectional view of the powder spray nozzle of Figure 2; Figure 4 in an enlarged view of a portion of the powder spray nozzle of Figure 2 showing the unclogging member in its retracted position, in solid lines, and in its projected position, in broken lines; and

[0069] Figure 5 is a schematic view of a powder spraying system according to the present disclosure.

[0070] Detailed Description

[0071] The skilled reader will recognise that one or more features of one aspect or embodiment of the present disclosure may be combined with one or more features of any other aspect or embodiment of the present disclosure unless the immediate context teaches otherwise.

[0072] Figure 1 shows schematically a powder spray nozzle 1 according to the present disclosure that comprises a powder inlet 2 configured to receive powder from a source of powder and a powder outlet 3 having an outlet orifice 4 configured to spray powder out of the powder spray nozzle 1. A first conduit 5 extends between the powder inlet 2 and the powder outlet 3. An unclogging member 6 is provided that is configured to be movable between a retracted position wherein the unclogging member 6 is held clear of the outlet orifice 4 and a projected position wherein a distal end of the unclogging member 6 is projected at least partially into the outlet orifice 4. In Figure 1 the unclogging member 6 is shown in its projected position.

[0073] In the example embodiments of the Figures the unclogging member 6 is illustrated as a rod 6.

[0074] In the example of Figure 1 an actuator 7, in the form of a pneumatic cylinder, is provided. The pneumatic cylinder is housed in a housing 8 separate from a nozzle body 9 of the powder spray nozzle 1. The pneumatic cylinder is configured to move the rod 6 from its projected position to its retracted position. The actuator 7 further comprises a spring force member 10 for moving the rod 6 from the retracted position to the projected position, for example when the pneumatic cylinder is deactivated.

[0075] In the example of Figure 1 a second conduit 11 for gas is provided. The second conduit 11 extends between a gas inlet 12 and a gas outlet 13, the gas outlet 13 being located in proximity to the powder outlet 3 such that a gas flowing through the second conduit 11 and out of the gas outlet 13 produces a suction force at the outlet orifice 4 of the powder outlet 3 to promote flow of a powder through the first conduit 5 and out of the outlet orifice 4.

[0076] Figures 2 to 4 show an example embodiment of a powder spray nozzle 1 according to the present disclosure. The powder spray nozzle 1 comprises a nozzle body 9 having a nozzle outlet 20, a first conduit 5 for the powder, and a second conduit 11 for gas. The first conduit 5 extends between the powder inlet 2, that may be connected to be in communication with a supply conduit, and the powder outlet 3. The second conduit 11 extends between the gas inlet 12 and the gas outlet 13. The gas outlet 13 is located in proximity to the powder outlet 3 such that a gas flowing through the second conduit 11 and out of the gas outlet 13 causes a reduction in pressure that produces a suction force at the powder outlet 3 to promote flow of the powder through the first conduit 5 and out of the powder outlet 3 and the nozzle outlet 20. The powder outlet 3 and the gas outlet 13 are orientated to promote mixing of the gas with the powder.

[0077] In the example embodiment of Figures 2 to 4 the nozzle body 9 comprises a plurality of parts that are assembled together. For example the nozzle body 9 as shown comprises a first body element 21, a second body element 22 and a cap element 23.

[0078] In the example embodiment of Figures 2 to 4 the second body element 22 is connected to the first body element 21 and the elements are sealed together with O-ring seals 24. Alternatively, the first body element 21 and the second body element 22 may be formed as a unitary part. The cap element 23 is connected to the second body element 22 and the elements are sealed together with a gasket seal 25.

[0079] In the example embodiment of Figures 2 to 4 a first tubular element 26 is provided that defines at least a portion of the first conduit 5 and the powder outlet 3. The first tubular element 26 is connected to, or comprises an integral part of, the second body element 22 of the nozzle body 9. The first tubular element 26 has a proximal portion that is cylindrical and of constant internal diameter. It further has a distal portion that is tapered with a decreasing internal diameter in the direction of the powder outlet. It further has a terminal portion that itself defines the outlet orifice 4 of the powder outlet 3 that is cylindrical and of constant internal diameter.

[0080] In the example embodiment of Figures 2 to 4 a second tubular element 27 is provided that defines another portion of the first conduit 5 and the powder inlet 2. The second tubular element 27 is connected to, or comprises an integral part of, the first body element 21 of the nozzle body 9. The second tubular element 27 has a proximal portion that itself defines the powder inlet 2 and is cylindrical and of constant internal diameter. It further has a distal portion that is tapered with a decreasing internal diameter in the direction of the first tubular element 26. It may optionally further have a terminal portion that is connected to the proximal portion of the first tubular element 26 that is cylindrical and of constant internal diameter.

[0081] In the example embodiment of Figures 2 to 4 the first conduit 5 comprises a bore whose internal diameter decreases from a first diameter at the powder inlet 2 to a second diameter at or adjacent the powder outlet, for example exclusively via one or more tapered sections, i.e. the distal portion and the distal portion. The bore of the first conduit 5 is smooth and absent any abrupt inwardly-directed shoulders or crevices that might present obstructions or collection points for the powder, e.g. dry powder, in use.

[0082] In the example embodiment of Figures 2 to 4 the cap element 23 is coupled over a distal end of the first tubular element 26. The cap element 23 comprises an aperture that constitutes the nozzle outlet 20. When coupled together, the distal end of the first tubular element 26 is arranged in or adjacent the aperture in the cap element 23 such that an annular clearance 28 between the first tubular element 26 and the cap element 23 defines the gas outlet 13. The annular clearance 28 between the first tubular element 26 and the cap element 23 may be 0.2 to 2.0 mm, optionally 0.2 to 1.0 mm, optionally 0.25 to 0.9 mm, optionally 0.6 mm.

[0083] In the example embodiment of Figures 2 to 4 the second body element 22 defines in part the second conduit 11. The gas inlet 12 is orientated in a transverse direction, e.g. located on a side face of the nozzle body 9. The second conduit 11 comprises a first portion that extends transversely from the gas inlet 12 and a second portion that extends longitudinally from the first portion to the gas outlet 13. In the example embodiment of Figures 2 to 4 the first tubular element 26 is received within the second portion of the second conduit 11 such that the second conduit 11 in that region comprises an annular conduit 29 extending between an interior face of the second body element 22 and an exterior face of the first body element 21.

[0084] The powder outlet 3 in this embodiment has a single outlet orifice 4. The outlet orifice 4 is provided in the distal end of the first tubular element 26 and is orientated along the longitudinal axis of the nozzle body 9. The outlet orifice 4 may have an orifice diameter of 0.5 to 5.0 mm, optionally 1.0 to 2.5 mm, optionally 1.0 to 2.0 mm.

[0085] In use, the powder inlet 2 is connected to a supply conduit 102 of a powder spraying system 100 as shown schematically in Figure 5. The gas inlet 12 is connected to a feed line. A flow of gas from the feed line enters the powder spray nozzle 1 through the gas inlet 12 and passes along the first portion and second portion before exiting through the gas outlet 13 and nozzle outlet 20. The flow of the gas passing in proximity to the powder outlet 3 causes a reduction in pressure producing a suction force at the powder outlet 3. This suction force assists flow of the powder down through the first conduit 5. The powder from the supply conduit 102 is fed into the powder inlet 2 by gravity and the action of gravity drives the powder down the first conduit 5. The suction force at the powder outlet 3 assists in the movement of the powder, for example by helping to draw the powder towards the powder outlet 3 and / or by fluidising the powder in the first conduit 5 in the vicinity of the powder outlet 3.

[0086] The powder outlet 3 and the gas outlet 13 are orientated to promote mixing of the gas with the powder, for example in the region exterior to the nozzle body 9 and downstream of the nozzle outlet 20. The mixing of the gas with the powder assists in dispersion and / or deagglomeration of the powder.

[0087] In the example embodiment of Figures 2 to 4 the rod 6 is provided as part of the powder spray nozzle 1 that is configured to be movable between the retracted position and the projected position. The retracted position is shown in Figure 2 wherein the rod 6 is held clear of the outlet orifice 4. Figure 4 illustrates the relative movement of the rod 6 - the retracted position of the distal end is shown in the solid lines 31 and its projected position is shown in broken lines 32. In the illustrated example in the projected position the distal end 30 of the rod 6 is projected at least partially into the outlet orifice 4 of the powder outlet. In the example embodiment of Figures 2 to 4 the rod 6 is a straight elongate stainless steel rod having a cross-sectional shape that matches the shape of the outlet orifice 4, for example a round cross-sectional shape and a circular outlet orifice 4. In the embodiment of Figures 2 to 4 the rod 6 is a solid rod. In the embodiment of Figures 2 to 4 the distal end 30 is squared off. However, in alternative embodiments the distal end 30 may be tapered, pointed or rounded.

[0088] In the example embodiment of Figures 2 to 4 the amount of movement of the rod 6 between its retracted and projected positions is set at 5 to 40 mm.

[0089] In the example embodiment of Figures 2 to 4 the rod 6 extends within the first conduit 5 and in the retracted position the distal end of the rod 6 is located within the first conduit 5.

[0090] A proximal end of the rod 6 may extend through an exterior wall of the nozzle body 9 and be coupled in a suitable manner with the actuator 7, for example the pneumatic cylinder as illustrated schematically in Figure 1.

[0091] In use operating the powder spray nozzle 1 comprises the steps of: receiving powder from a source of powder 101 into a powder inlet 2 of the powder spray nozzle 1 ; conveying the powder along a first conduit 5 to a powder outlet 3 of the powder spray nozzle 1 and spraying the powder out of the powder spray nozzle 1 through an outlet orifice 4 ; and intermittently clearing accumulated powder from the outlet orifice 4 by using a rod 6 of the powder spray nozzle 1 wherein the rod 6 is moved from a retracted position in which the rod 6 is held clear of the outlet orifice 4 into a projected position in which the distal end 30 of the rod 6 is projected at least partially into the outlet orifice 4 to dislodge accumulated powder from the outlet orifice 4.

[0092] In some embodiments after each clearing the rod 6 is retracted into the retracted position. Movement of the rod 6 is effected by an actuator 7, optionally a pneumatic cylinder, hydraulic actuator 7 or electromagnetic solenoid.

[0093] The powder spray nozzle 1 may form a part of a powder spraying system 100 as shown schematically in Figure 5 that comprises a source of dry powder 101, the powder spray nozzle 1 and a supply conduit 102 connecting the source of dry powder 101 with the powder inlet 2 of the powder spray nozzle 1.

[0094] In some embodiments the powder is fed along the supply conduit 102 by gravity. Alternatively a carrier gas may be used to entrain and move the powder.

[0095] In some embodiments the source of powder 101 is a reservoir. The reservoir may comprise one or more hoppers. The reservoir may comprise a dosing device. The dosing device may dose the powder by one or more of by weight, by volume, by particle number, by time. The dosing device may be located at or near an outlet of the reservoir or alternatively within the supply conduit 102. The dosing device may be gravimetrically fed with the powder from the reservoir.

[0096] The supply conduit 102 transports the powder from the source of powder 101 to the powder spray nozzle 1. The supply conduit 102 may comprise one or more components.

[0097] The supply conduit 102 may comprise one or more conduits, for example, passages, pipes, hoses, etc.

Claims

Claims:

1. A powder spray nozzle comprising: a powder inlet configured to receive powder from a source of powder; a powder outlet having an outlet orifice configured to spray powder out of the powder spray nozzle; a first conduit extending between the powder inlet and the powder outlet; and an unclogging member configured to be movable between a retracted position in which the unclogging member is held clear of the outlet orifice and a projected position in which a distal end of the unclogging member is projected at least partially into the outlet orifice.

2. A powder spray nozzle as claimed in claim 1 , wherein the unclogging member extends within the first conduit and in the retracted position the distal end of the unclogging member is located within the first conduit.

3. A powder spray nozzle as claimed in 1 or claim 2, further comprising an actuator coupled to the unclogging member for moving the unclogging member from the projected position to the retracted position and / or from the retracted position to the projected position.

4. A powder spray nozzle as claimed in claim 3, wherein the actuator comprises a pneumatic cylinder.

5. A powder spray nozzle as claimed in claim 4, wherein the pneumatic cylinder is housed in a housing separate from a nozzle body of the powder spray nozzle.

6. A powder spray nozzle as claimed in any preceding claim, further comprising a spring force member for moving the unclogging member from the retracted position to the projected position and / or from the projected position to the retracted position.

7. A powder spray nozzle as claimed in any preceding claim, wherein in the projected position the unclogging member is projected fully into the outlet orifice, and optionally is projected into and through the outlet orifice.

8. A powder spray nozzle as claimed in any preceding claim, wherein in the projected position an annular clearance is provided between the unclogging member and a body of the powder spray nozzle such that the outlet orifice is not sealed in a fluid-tight manner.

9. A powder spray nozzle as claimed in any preceding claim, wherein the unclogging member is a rod.

10. A powder spray nozzle as claimed in any preceding claim, further comprising a second conduit for gas, the second conduit extending between a gas inlet and a gas outlet, the gas outlet being located in proximity to the powder outlet such that a gas flowing through the second conduit and out of the gas outlet produces a suction force at the outlet orifice of the powder outlet to promote flow of a dry powder through the first conduit and out of the outlet orifice.

11. A powder spray nozzle as claimed in any preceding claim, wherein the powder inlet, powder outlet, and the first conduit are comprised in a nozzle body of the powder spray nozzle.

12. A powder spray nozzle as claimed in any preceding claim, wherein the first conduit comprises a bore whose internal diameter decreases from a first diameter at the powder inlet to a second diameter at or adjacent the powder outlet; and optionally: wherein the first conduit comprises a bore whose internal diameter smoothly decreases from a first diameter at the powder inlet to a second diameter at or adjacent the powder outlet; and optionally: wherein the first conduit comprises a bore whose internal diameter decreases from a first diameter at the powder inlet to a second diameter at or adjacent the powder outlet exclusively via one or more tapered sections.

13. A powder spraying system comprising: a) a source of dry powder; b) a powder spray nozzle as claimed in any preceding claim; and c) a supply conduit connecting the source of dry powder with the powder inlet of the powder spray nozzle.

14. A method of operating a powder spray nozzle comprising the steps of: receiving powder from a source of powder into a powder inlet of the powder spray nozzle; conveying the powder along a first conduit to a powder outlet of the powder spray nozzle and spraying the powder out of the powder spray nozzle through an outlet orifice; and intermittently clearing accumulated powder from the outlet orifice by using an unclogging member of the powder spray nozzle wherein the unclogging member is moved from a retracted position in which the unclogging member is held clear of the outlet orifice into a projected position in which a distal end of the unclogging member is projected at least partially into the outlet orifice to dislodge accumulated powder from the outlet orifice.

15. The method of claim 14, wherein after each clearing the unclogging member is retracted into the retracted position; and optionally: wherein movement of the unclogging member is effected by an actuator, optionally a pneumatic cylinder.

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