EP4701786A1

EP4701786A1 - Method and apparatus for applying inorganic particles to a filter body with dry aerosol and binder

Info

Publication number: EP4701786A1
Application number: EP24724670.5A
Authority: EP
Inventors: Huiqing Wu
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2023-04-26
Filing date: 2024-04-04
Publication date: 2026-03-04
Also published as: CN121693393A; WO2024226251A1

Abstract

Apparatus and methods are disclosed which apply inorganic particles to a filter body such as a plugged honeycomb body with dry aerosol and liquid binder.

Description

METHOD AND APPARATUS FOR APPLYING INORGANIC PARTICLES TO A FILTER BODY WITH DRY AEROSOL AND BINDER

Cross Reference to Related Application

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63/462085, filed on April 26, 2023, the content of which is relied upon and incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] Embodiments of the present disclosure generally relate to methods and apparatus for aerosol deposition of inorganic particles to filter bodies with porous honeycomb structures, and the filter bodies having the inorganic deposits.

BACKGROUND

[0003] Particulate filters, for example, diesel particulate filters and gasoline particulate filters (GPFs), filter particulates from the exhaust stream from vehicle engines burning diesel or gasoline fuel, respectively.

[0004] There is a need for improved methods and apparatus to achieve filters with higher filtration efficiency.

SUMMARY

[0005] In one or more aspects, an apparatus is disclosed herein which is configured to apply inorganic particles to a target body. The target body may be a plugged honeycomb body comprising a honeycomb structure comprised of porous walls, an inlet end and an outlet end, the porous walls extending axially from the inlet end to the outlet end and intersecting in a cellular configuration, the porous walls comprising surfaces which define axial channels. The apparatus comprises: a mixing duct comprising one or more internal surfaces defining a chamber extending from a proximal portion to a distal portion; a powder delivery device (which serves as a dry powder source) comprising a powder inlet conduit configured to deliver powder particles to the chamber; a liquid delivery device comprising a liquid inlet conduit configured

1

SUBSTITUTE SHEET (RULE 26) to deliver liquid droplets to the chamber; and a target body holding device connected to the distal portion of the mixing duct, wherein the mixing duct is configured to accommodate flow in a downstream direction from the proximal portion to the distal portion; wherein the powder inlet conduit is connected to the proximal portion of the mixing duct at a powder inlet location; and wherein the liquid inlet conduit is connected to the proximal portion of the mixing duct at a liquid inlet location.

[0006] In other aspects, a method is disclosed herein of applying inorganic particles to a target body, the method comprising: flowing powder particles into a chamber of a mixing duct; flowing liquid droplets into the chamber, wherein the liquid droplets comprise a binder material (binder-containing liquid droplets), and wherein the powder particles and the liquid droplets are kept separated prior to entry into the chamber; mixing the powder particles and the liquid droplets in the chamber to form agglomerates of the powder particles and the binder material; flowing the agglomerates toward a target body; and depositing the agglomerates on the target body. The target body can then be heated to cure the binder and adhere the agglomerates to the target body and/or to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0008] FIG. 1 schematically illustrates an embodiment of an apparatus disclosed herein, which may also be referred to as a DAwB deposition unit for a DAwB process.

[0009] FIG. 2 schematically illustrates in flow chart form a process flow disclosed herein of dry aerosol with binder deposition DAwB.

[0010] FIG. 3 shows droplet size distribution of binder aerosol for an embodiment disclosed herein.

[0011] FIG. 4 shows binder aerosol throughput measurements wherein the throughput of binder aerosol was measured by weighing in an embodiment disclosed herein. [0012] FIG. 5 shows a comparison of performance of (a) filtration efficiency vs filtration deposit material loading and (b) smoke FE/dP tradeoff for an SBB apparatus and process vs. a

DAwB apparatus and process disclosed herein.

[0013] FIG. 6 shows water resistance of DAWB vs SBB at 93% smoke FE.

[0014] FIG. 7 shows photographs of top views (a) and cross-sectional cutaway views (b) of filtration material deposits on ceramic honeycomb walls as produced by DAwB and as produced by SBB.

DETAILED DESCRIPTION

[0015] Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.

[0016] In aspects disclosed herein, an apparatus is configured to apply inorganic particles to a target body. In embodiments, the target body is a plugged honeycomb body comprising a honeycomb structure comprised of porous walls, an inlet end and an outlet end, the porous walls extending axially from the inlet end to the outlet end and intersecting in a cellular configuration, the porous walls comprising surfaces which define axial channels. Unless otherwise noted herein, powder refers to dry powder, comprising dry inorganic particles.

[0017] In embodiments, the apparatus comprises: a mixing duct comprising one or more internal surfaces defining a chamber extending from a proximal portion to a distal portion; a powder delivery device, or powder source, comprising a powder inlet conduit configured to deliver dry powder particles to the chamber; a liquid delivery device, or liquid delivery source, comprising a liquid inlet conduit configured to deliver liquid droplets to the chamber; and a target body holding device connected to the distal portion of the mixing duct, wherein the mixing duct is configured to accommodate flow from the proximal portion to the distal portion, i.e. in a downstream direction; wherein the powder inlet conduit is connected to the proximal portion of the mixing duct at a powder inlet location; and wherein the liquid inlet conduit is connected to the proximal portion of the mixing duct at a liquid inlet location.

[0018] Preferably, the liquid inlet location is disposed closer to the distal portion of the chamber than the powder inlet location. [0019] In embodiments, the mixing duct is vertically oriented with the proximal portion disposed above the distal portion.

[0020] In embodiments, the powder inlet location is configured to allow the powder particles to flow vertically downward into the chamber. In embodiments, the powder inlet location is upstream of the liquid inlet location.

[0021] In embodiments, the liquid inlet location is configured to allow the liquid droplets to enter the chamber horizontally.

[0022] In embodiments, the chamber is configured to allow mixing of the powder particles and the liquid droplets before reaching the target holding portion.

[0023] In embodiments, the powder delivery device further comprises a powder disperser configured to disperse powder particles and to deliver the powder particles to the powder inlet conduit. In embodiments, the powder delivery device further comprises a blower configured to transport the powder particles to the powder inlet conduit with a carrier gas. In embodiments, the carrier gas provides motive force to the powder particles and the liquid droplets to flow through the chamber toward the target. In embodiments, the carrier gas aids gravity in providing a motive force to the powder particles and the liquid droplets to flow through the chamber toward the target.

[0024] In embodiments, the liquid delivery device further comprises a liquid aerosol generator configured to atomize a liquid into liquid droplets and to deliver the liquid droplets to the liquid inlet conduit.

[0025] In embodiments, the target body is a honeycomb body comprising a honeycomb structure comprised of porous walls, an inlet end and an outlet end, the porous walls extending axially from the inlet end to the outlet end and intersecting in a cellular configuration defining a plurality of axial channels, the porous walls comprising surfaces which define axial channels. [0026] In embodiments, a first subset of the channels are plugged near the outlet end and are open at the inlet end, and a second subset of the channels are plugged near the inlet end and are open at the outlet end.

[0027] In embodiments, a dry powder inlet conduit is configured to deliver dry powder particles to the chamber.

[0028] In embodiments, the apparatus further comprises a HEPA filter downstream of the target holding portion. [0029] In embodiments, the apparatus contains no heater. In embodiments, the apparatus is configured to operate at room temperatures.

[0030] In other aspects disclosed herein, a method of applying inorganic particles to a target body, the method comprising: flowing powder particles into a chamber of a mixing duct; flowing liquid droplets (preferably binder-containing liquid droplets) into the chamber, wherein the liquid droplets comprise a binder material, and wherein the powder particles and the liquid droplets are kept separated prior to entry into the chamber; mixing the powder particles and the liquid droplets in the chamber to form agglomerates of the powder particles and the binder material; flowing the agglomerates toward a target body; and depositing the agglomerates on the target body.

[0031] In embodiments, upon entering the chamber, the liquid droplets are comprised of the binder material and a mixture liquid.

[0032] In embodiments, the agglomerates are dried in the chamber to remove the mixture liquid from the agglomerates prior to the depositing. In embodiments, the drying in the chamber occurs at one or more temperatures which are less than 50 °C.

[0033] In embodiments, the powder particles are introduced into the chamber at a proximal portion of the duct, the liquid droplets are introduced into the chamber at a liquid droplet inlet portion downstream of the proximal portion, and the target body is disposed downstream of the liquid droplet inlet portion.

[0034] In embodiments, the downstream direction comprises a vertical orientation with the proximal portion disposed above the distal portion.

[0035] In embodiments, a binder-containing liquid is atomized to form the liquid droplets prior to the liquid droplets entering into the chamber.

[0036] In embodiments, the binder material comprises a siloxane.

[0037] In embodiments, the powder particles are dispersed and conveyed by a carrier gas prior to the powder particles entering into the chamber.

[0038] In embodiments, the method further comprises curing the binder material in the agglomerates on the target body. In embodiments, the curing step comprises heating the target body after the agglomerates have been deposited on the target body. In embodiments, the target body is exposed to a gaseous flow at one or more temperatures greater than 50 °C. In embodiments, the target body is exposed to a gaseous flow at one or more temperatures greater than 70 °C. In embodiments, the target body is exposed to a gaseous flow at one or more temperatures greater than 90 °C. In embodiments, the target body is exposed to a gaseous flow at one or more temperatures greater than 100 °C. In embodiments, the target body is exposed to a gaseous flow at one or more temperatures greater than 150 °C. In embodiments, the target body is exposed to a gaseous flow at one or more temperatures greater than 190 °C for 20 to 120 minutes.

[0039] In embodiments, the binder material is water soluble.

[0040] In embodiments, the binder material is silicon-containing. In embodiments, the binder material is a silicone resin, a siloxane, an alkalisiloxane, alkoxysiloxane, or a silicate. In embodiments, the binder material is one or more of a silicone resin, a siloxane, an alkalisiloxane, an alkoxy siloxane, a silicate, or combinations thereof. In embodiments, the binder material is a water-soluble silicon containing binder material. In embodiments, the binder material is an alkaline silicate or sodium silicate.

[0041] In embodiments, the binder-containing liquid further comprises water.

[0042] In embodiments, the powder comprises one or more of alumina, silica, cordierite, silicon carbide, or combinations thereof. In embodiments, the alumina is alpha alumina (a- AI2O3).

[0043] In other aspects, a method is disclosed herein of applying an inorganic deposit treatment to a honeycomb body comprising a honeycomb structure comprised of a plurality of walls extending in an axial direction from an inlet end to an outlet end, wherein at least some of the walls intersect with each other in a network of cells comprised of cell walls defining a plurality of channels, the method comprising: delivering a dry powder of inorganic particles, i.e. “powder particles”, into a mixing chamber; delivering binder droplets into the mixing chamber at the same time the powder particles are delivered; mixing the powder particles with the binder droplets in the mixing chamber to generate a mixture flow of inorganic particles and binder; and delivering the mixture flow to the honeycomb structure of the honeycomb body.

[0044] In embodiments, the binder droplets comprise a binder-containing liquid comprising a binder material. In embodiments, the binder material is silicon-containing. In embodiments, the binder material is a silicone resin, or a siloxane, or an alkalisiloxane, or an alkoxysiloxane, or a silicate, e.g., an alkaline silicate or sodium silicate. In embodiments, the binder material is one or more of a silicone resin, a siloxane, an alkalisiloxane, an alkoxysiloxane, a silicate, or combinations thereof. In embodiments, the binder material is a water soluble silicon containing binder material. In embodiments, the binder material is an alkaline silicate or sodium silicate. In embodiments, the binder-containing liquid further comprises a mixture liquid. In embodiments, the mixture liquid is water.

[0045] In embodiments, the inorganic particles of the powder are dry upon delivery to the mixing chamber. In embodiments, the inorganic particles are sprayed into the mixing chamber. In embodiments, the binder droplets are sprayed into the mixing chamber.

[0046] In embodiments, the inorganic particles are wetted by the binder droplets within the mixture flow to produce binder-wetted inorganic particles. In embodiments, the binder-wetted inorganic particles are delivered to the honeycomb structure.

[0047] In embodiments, the mixture flow is comprised of binder-wetted inorganic particles. In embodiments, the mixture flow further comprises dry inorganic particles and binder droplets, for example those which may have not yet contacted each other.

[0048] In embodiments, the powder is dispersed upon entry to the mixing chamber. In embodiments, the powder is dispersed via a flow of air, preferably compressed air. In embodiments, the powder is dispersed via transport through a venturi tube.

[0049] In embodiments, the binder droplets are delivered to the mixing chamber as a liquid aerosol. In embodiments, the liquid aerosol is comprised of binder droplets generated by an air flow and a liquid binder material. In embodiments, the binder droplets are generated by atomizing liquid binder with an air flow.

[0050] In embodiments, the mixture flow is delivered to the honeycomb structure of the filter body via a duct.

[0051] In embodiments, the binder-wetted inorganic particles are deposited within the honeycomb structure. In embodiments, the binder-wetted inorganic particles are deposited on surfaces of the walls, or within the walls, or both, of the honeycomb structure. In embodiments, the binder-wetted inorganic particles are deposited on surfaces of the walls, or within the walls, or both, of the honeycomb structure.

[0052] In embodiments, the honeycomb body comprises a plurality of plugs which seal a first subset of cells at or near the inlet end (“outlet cells”) and a second subset of cells at or near the outlet end (“inlet cells”). In embodiments, the binder-wetted inorganic particles are deposited on or in inlet cell walls. In embodiments, the binder-wetted inorganic particles are deposited on or in outlet cell walls.

[0053] In embodiments, the honeycomb body is exposed to a heat treatment sufficient to cure the binder material. In embodiments, curing the binder material causes the inorganic particles to physically adhere to the cell walls, to each other, or both. In embodiments, curing the binder material completely dries the inorganic particles. In embodiments, curing the binder material causes silica content from the binder to adhere to the inorganic particles, the cell walls, or both. In embodiments, the curing comprises exposing the honeycomb body to temperatures of 100 C to 500 C for a time from 0.5 hours to 4 hours. In embodiments, the honeycomb body is exposed to a heat treatment of 600 to 1200 °C for a period of 1 to 24 hours. In embodiments, the honeycomb body supports 1 g/L to 10 g/L, or 1 g/L to 7 g/L, of inorganic particles per volume of honeycomb body.

[0054] In embodiments, the heat treatment is sufficient to cause the honeycomb body to exhibit a clean-state filtration efficiency as measured by smoke FE test of greater than 90%, and in some embodiments greater than 91%, and in some embodiments greater than 92%, and in some embodiments greater than 93%.

[0055] In embodiments, the heat treatment is sufficient to cause the honeycomb body to exhibit a clean-state filtration efficiency as measured by smoke FE test, and a change in clean-state filtration efficiency of less than 3% after the honeycomb body is exposed to a nebulizer test.

[0056] In embodiments, (1) the delivering the dry powder into the mixing chamber, (2) the delivering binder droplets into the mixing chamber simultaneously with the delivering the dispersed powder, (3) the mixing the dispersed powder with the binder droplets in the mixing chamber to generate a mixture flow of powder particles and binder, and (4) the delivering the mixture flow to the honeycomb structure of the filter body, are each carried out at one or more temperatures below 50 C, or below 40 C, or below 35 C, for example greater than 0 C and less than 35 C.

[0057] In embodiments, the powder comprises one or more of alumina, silica, cordierite, silicon carbide, or combinations thereof. In embodiments, the alumina is alpha alumina (a- AI2O3).

[0058] In embodiments, the carrier gas that transports the powder, as well as the liquid droplets and agglomerates, is air, such as from a compressed air source. Preferably, such as due to potential extra cost and extra supporting equipment, no separate nitrogen gas or other gas such as inert gas is injected into the chamber. Preferably the powder particles are not mixed with any solvent and are dry or essentially dry.

[0059] In embodiments, a dry powder, or dry powders and a liquid binder are capable of being separately controlled, i.e., under separate control, and their mixing and deposition is preferably in air flow, preferably at room temperature or ambient temperature at the time of deposition. Such embodiments may be referred to herein as “dry aerosol with binder deposition” method and/or apparatus (DAwB).

[0060] In exemplary embodiments, the dry powder is an inorganic refractory material such as a-A12O3 (alpha alumina), cordierite, or silicon carbide; The liquid binder is a siloxane binder or sodium silicate binder. The apparatuses and methods disclosed to herein allow such materials to be used without pre-treatment.

[0061] In embodiments, the mixing of dispersed powders and binder droplets is conducted in the deposition chamber.

[0062] In embodiments, the only gas needed is compressed air for the dispersion and delivery of dry powders and liquid aerosol droplets.

[0063] For example, the presently disclosed dry powder aerosol delivery plus liquid binder delivery are controlled as two separate inlet spray streams which avoids the need of known apparatuses/methods for mixing together the inorganic particles (for example in a liquid suspension) and the liquid binder to form a suspension which is then atomized and delivered to the chamber of the duct, such as with a spray-drying and deposition (“SDD”) process for improving the filtration performance of ceramic filter products like gasoline particulate filter (GPF) and/or diesel particulate filter (DPF), wherein for the SDD process, a liquid suspension of powders and solvent is atomized and sprayed into a heated chamber to form dry agglomerates, which are then directed or drawn into filters by a blower and/or a vacuum blower to deposit filtration material on the porous filter channel walls.

[0064] In embodiments herein, a commercially available dry powder disperser can be used to help generate a flow of the dry powder particles. In embodiments, a commercially available liquid aerosol generator can be used to supply the liquid droplets. The disperser and generator may be attached to the chamber through respective conduits.

[0065] We have found that the presently disclosed aspects can provide filtration deposits on ceramic honeycomb filter bodies in an alternative way which has fewer requirements and/or variables of material and process than known methods or apparatuses, and surprisingly produce filter bodies with filtration deposits that provide comparable performance in filtration deposit loading efficiency, and robustness in durability and and/or reliability in preserving such performance features, without negatively impacting the filtration efficiency/pressure drop (FE/dP) tradeoff of any significance, while providing enhanced filtration efficiency with minimal increase or impact to pressure drop through the filter, and with durability of the deposited filtration material to stay in place during use of the filter (such as a gasoline particular filter GPF) such that degradation of filtration efficiency after exposure to water, for example, is small and the impact to pressure drop remains small as well.

[0066] FIG. 1 schematically illustrates an embodiment of an apparatus disclosed herein, which may also be referred to as a DAwB deposition unit for a DAwB process. A prototype was built for validation and process parameter studies. The deposition unit comprised a dry powder disperser, a liquid aerosol generator and a dual-section chamber. The powder disperser and dual-section chamber were as described in PCT Patent Application Publication Serial No. PCT/CN2022/089704 filed on 04/28/2022 which is incorporated herein by reference. The liquid aerosol generator was commercially available and was used to generate a polydisperse aerosol in high concentrations. The system had a built-in pressure regulator and pressure gauge, as well as a self-contained dilution system. External controls allow one through six particlegenerating atomizer jets to be selected, each producing aerosol concentrations greater than 10E7 particles/cm³ at 6.5 L/min (nominal at 25 psig pressure), allowing both the aerosol number concentration and the total aerosol output to be adjusted. Precise control of dilution air flow rate allows further control over the output concentration and aerosol emission. Different from the position where dispersed powders introduced, atomized liquid aerosol was sprayed into the upper section of the deposition chamber but downstream of the dry powder stream inlet. And the dry powder particles were mixed with the atomized liquid aerosol before they were deposited into a GPF target body. A powder dispenser delivered dry powder particles to the air stream generated by the blower and flowed through the conduit into the top of the duct for entry into the chamber of the duct.

[0067] FIG. 2 schematically illustrates in flow chart form a process flow disclosed herein of dry aerosol with binder deposition. The process can be described as separate spray of solid particles and liquid binder into the chamber, mixing of dispersed particles and binder droplets, filter material deposits or filtration layer deposition or membrane deposition, and cure treatment. The powder dispersion process was as described in PCT Patent Application Publication Number WO2021/217389 published on 04 November 2021. When using the prototype shown in FIG. 1, dry powders were sheared sharply and rushed out through the rear of a Venturi tube into the deposition chamber. In the trials, the air pressure was controlled at 6 bar and particle loading rate at 4 cm/min. At the same time, commercial siloxane binder was dispersed into small droplets by a six-jet atomizer with the aid of compressed air flow. The air pressure was set at 8 bar and the dilution flow was controlled at 100 L/min. When the binder droplets encountered the dry powders, they mixed with each other. A GPF part (target body) was fixed at the lower section of chamber, so that the mixture of particle and binder, which formed agglomerates and/or aggregates of the mixture, could be directly blown into GPF filter channels by air flow managed by a fan. An inline smoke FE/DP measurement of as-deposited filter was measured to determine the termination of deposition. Finally, the filter was removed from the deposition apparatus and was treated at 200°C for 1 hour to complete the cure of binder for filtration membrane binding strength (durability) enhancement. Each step of this DAwB process was completed at room temperature except the cure. Also, no solvent was involved in this process, and therefore no heating was needed.

[0068] FIG. 3 shows droplet size distribution of binder aerosol. The droplet size distribution (DSD) and throughput of binder aerosol were measured with all six atomizer jets turned on. DSD was tested by a light-scattering aerosol spectrometer and the number-based d50 was around 0.56 pm with a span (dB = (d90-dl0)/d50) of 1.25.

[0069] FIG. 4 shows binder aerosol throughput measurements wherein the throughput of binder aerosol was measured by weighing. Weight of the generator was recorded every minute with all six jets opened and the average output was around 0.418 g/min.

[0070] FIG. 5 shows performance of (a) filtration efficiency vs filtration deposit material loading and (b) smoke FE/dP tradeoff. Loading efficiency and FE/dP tradeoff may be used to assess filtration material deposition performance. As shown in FIG. 5, the DAwB deposition required more filtration material loading amount to reach the same FE target as SBB, which if all other parameters are the same means the DAwB loading efficiency was lower. For example, the loading for DAwB to reach 93%FE was 4.99 g/L while it was 4.12g/L for SBB. One adjustment may be to increase the loading to achieve similar FE. As to the FE/dP tradeoff, DAwB performed better and provided lower dP.

[0071] FIG. 6 shows water resistance of DAWB vs SBB at 93% smoke FE. Besides the deposition performance, water reliability was another criterion for assessing filtration deposit performance. FIG. 6 shows that filtration deposits, after the ceramic bodies and their deposited filtration materials were exposed to a nebulizer (water) test, produced by DAwB provided similar water resistance as SBB and the total FE loss was <5% at 93%FE. [0072] FIG. 7 shows photographs of top views (a) and cross-sectional cutaway views of filtration material deposits on ceramic honeycomb walls as produced by DAwB and as produced by SBB. Both DAwB and SBB produce similar morphologies of filtration material deposits, for example agglomerate size, deposited patterns, depth of penetration into the porous ceramic walls.

[0073] To evaluate the filtration efficiency of the particulate filter comprising inorganic deposits, one FE test is a Smoke FE test using smoke particles or nanoparticles and the pressure drop across a filter can be measured at different flow rates, even without loading soot into or onto the filter part. The term “clean” refers to a zero soot loading or no soot loading. Unless otherwise noted, a soot loaded backpressure is measured at one flow rate (generally 357Nm³/hr). Procedures are described below for the “Smoke filtration efficiency test”.

[0074] To evaluate durability of the particulate filter comprising inorganic deposits, the abovereferenced filter article tested for filtration performance was further subjected to the following. [0075] A “smoke test” or “smoke FE test”, was conducted as follows. 300 nm median cigarette smoke particulate was used to measure the filtration efficiency. The upstream concentrations were 500,000 particles over 30 seconds which is equal to approximately 353 particles/cc with a 0.1 cfin flow rate into a Lighthouse Handheld 3016 particle counter. The particle number was collected for 30 seconds upstream and downstream simultaneously with two particle counters. The air velocity was 51 m³/h. The filtration efficiency was calculated based on reduction of particulate number concentration at downstream. The pressure drop was measured at the same flow rate by differential pressure gauge. Such smoke FE test could be used to evaluate FE before and after durability testing, and thus provide a measure of the durability of the filtration deposits. Such smoke FEtest could thus be used before and after durability testing of a filter part.

[0076] Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0077] Although the disclosure herein has been described with reference to particular embodiments, those skilled in the art will understand that the embodiments described are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, the present disclosure can include modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. An apparatus configured to apply inorganic particles to a target body, the apparatus comprising: a mixing duct comprising one or more internal surfaces defining a chamber extending from a proximal portion to a distal portion; a powder delivery device comprising a powder inlet conduit configured to deliver powder particles to the chamber; a liquid delivery device comprising a liquid inlet conduit configured to deliver liquid droplets to the chamber; and a target body holding device connected to the distal portion of the mixing duct, wherein the mixing duct is configured to accommodate flow in a downstream direction from the proximal portion to the distal portion; wherein the powder inlet conduit is connected to the proximal portion of the mixing duct at a powder inlet location; and wherein the liquid inlet conduit is connected to the proximal portion of the mixing duct at a liquid inlet location.

2. The apparatus of claim 1 wherein the liquid inlet location is disposed closer to the distal portion of the chamber than the powder inlet location.

3. The apparatus of claim 1 wherein the mixing duct is vertically oriented with the proximal portion disposed above the distal portion.

4. The apparatus of claims 1-3 wherein the powder inlet location is configured to allow the powder particles to flow vertically downward into the chamber.

5. The apparatus of claim 4 wherein the powder inlet location is upstream of the liquid inlet location.

6. The apparatus of claim 5 wherein the liquid inlet location is configured to allow the liquid droplets to enter the chamber horizontally.

7. The apparatus of claim 1 wherein the chamber is configured to allow mixing of the powder particles and the liquid droplets before reaching the target holding portion.

8. The apparatus of claim 1 wherein the powder delivery device further comprises a powder disperser configured to disperse powder particles and to deliver the powder particles to the powder inlet conduit.

9. The apparatus of claim 1 wherein the powder delivery device further comprises a blower configured to transport the powder particles to the powder inlet conduit with a carrier gas.

10. The apparatus of claim 9 wherein the carrier gas provides motive force to the powder particles and the liquid droplets to flow through the chamber toward the target.

11. The apparatus of claim 9 wherein the carrier gas aids gravity in providing a motive force to the powder particles and the liquid droplets to flow through the chamber toward the target.

12. The apparatus of claim 1 wherein the liquid delivery device further comprises a liquid aerosol generator configured to atomize a liquid into liquid droplets and to deliver the liquid droplets to the liquid inlet conduit.

13. The apparatus of claim 1 wherein the target body is a honeycomb body comprising a honeycomb structure comprised of porous walls, an inlet end and an outlet end, the porous walls extending axially from the inlet end to the outlet end and intersecting in a cellular configuration defining a plurality of axial channels, the porous walls comprising surfaces which define axial channels.

14. The apparatus of claim 13 wherein a first subset of the channels are plugged near the outlet end and are open at the inlet end, and a second subset of the channels are plugged near the inlet end and are open at the outlet end.

15. The apparatus of claim 1 wherein the apparatus further comprises a HEPA filter downstream of the target holding portion.

16. The apparatus of claim 1 wherein the apparatus contains no heater.

17. A method of applying inorganic particles to a target body, the method comprising: flowing powder particles into a chamber of a mixing duct; flowing liquid droplets into the chamber, wherein the liquid droplets comprise a binder material, and wherein the powder particles and the liquid droplets are kept separated prior to entry into the chamber; mixing the powder particles and the liquid droplets in the chamber to form agglomerates of the powder particles and the binder material; flowing the agglomerates toward a target body; depositing the agglomerates on the target body.

18. The method of claim 17 wherein upon entering the chamber, the liquid droplets are comprised of the binder material and a mixture liquid.

19. The method of claim 18 wherein the agglomerates are dried in the chamber to remove the mixture liquid from the agglomerates prior to the depositing.

20. The method of claim 19 wherein the drying in the chamber occurs at one or more temperatures which are less than 50 °C.

21. The method of claim 17 wherein the powder particles are introduced into the chamber at a proximal portion of the duct, the liquid droplets are introduced into the chamber at a liquid droplet inlet portion downstream of the proximal portion, and the target body is disposed downstream of the liquid droplet inlet portion.

22. The method of claim 21 wherein the downstream direction comprises a vertical orientation with the proximal portion disposed above the distal portion.

23. The method of claim 17 wherein a binder-containing liquid is atomized to form the liquid droplets prior to the liquid droplets entering into the chamber.

24. The method of claim 17 wherein the binder material comprises a siloxane.

25. The method of claim 17 wherein the powder particles are dispersed and conveyed by a carrier gas prior to the powder particles entering into the chamber.

26. The method of claim 17 further comprising curing the binder material in the agglomerates on the target body.

27. The method of claim 26 wherein the curing step comprises heating the target body.

28. The method of claim 26 wherein the target body is exposed to a gaseous flow at one or more temperatures greater than 50 °C.

29. The method of claim 28 wherein the target body is exposed to a gaseous flow at one or more temperatures greater than 70 °C.

30. The method of claim 28 wherein the target body is exposed to a gaseous flow at one or more temperatures greater than 90 °C.

31. The method of claim 28 wherein the target body is exposed to a gaseous flow at one or more temperatures greater than 100 °C.

32. The method of claim 28 wherein the target body is exposed to a gaseous flow at one or more temperatures greater than 150 °C.

33. The method of claim 28 wherein the target body is exposed to a gaseous flow at one or more temperatures greater than 190 °C for 20 to 120 minutes.

34. The method of claim 17 wherein the binder material is silicon-containing.

35. The method of claim 17 wherein the binder material is a silicone resin, a siloxane, an alkalisiloxane, alkoxysiloxane, or a silicate.

36. The method of claim 17 wherein the binder material is one or more of a silicone resin, a siloxane, an alkalisiloxane, an alkoxy siloxane, a silicate, or combinations thereof.

37. The method of claim 17 wherein the binder material is a water-soluble silicon containing binder material.

38. The method of claim 17 wherein the binder material is an alkaline silicate or sodium silicate.

39. The method of claim 17 wherein the binder-containing liquid further comprises water.

40. The method of claim 17 wherein the powder comprises one or more of alumina, silica, cordierite, silicon carbide, or combinations thereof.

41. The method of claim 17 wherein the alumina is alpha alumina (a-A12O3).