JPWO2021028691A5 - - Google Patents

Claims (25)

A method of treating a filter for filtering particulate matter from an exhaust gas comprising:
a) placing the dry powder in a reservoir;
b) placing a filter in a filter holder, said filter comprising a porous substrate having an inlet surface and an outlet surface, said inlet surface and said outlet surface being separated by a porous structure; a step of placing,
c) establishing a primary gas flow through said porous structure of said filter by applying a pressure drop to said outlet face of said filter;
d) transferring said dry powder from said reservoir to a spray device located upstream of said inlet face of said filter;
e) directing the dry powder, using the atomizing device, toward the inlet face of the filter so that it is entrained in the primary gas stream, passes through the inlet face of the filter and contacts the porous structure; and spraying said dry powder with a. The transfer of said dry powder from said reservoir to said atomization device is controllable independently of establishing and controlling said primary gas flow, optionally said drying powder towards said inlet face of said filter. 2. The method of claim 1, wherein powder atomization is controllable independently of establishing and controlling the primary gas flow. 3. A method according to claim 1 or 2, wherein the primary gas flow is established before the dry powder is transferred to the atomization device and atomized towards the inlet face. In step d) a secondary gas stream separate from said primary gas stream is used to transport said dry powder from said reservoir to said atomization device, optionally said secondary gas stream is A method according to any one of claims 1 to 3, which is controllable independently of the gas flow. 5. A method according to claim 4, wherein said secondary gas stream comprises a stream of compressed gas, preferably air. A method according to any preceding claim, comprising using a vacuum generator to establish the primary gas flow through the porous structure of the filter. 7. The method of claim 6, wherein the level of pressure drop generated by the vacuum generator is controllable independently of the rate or mass flow rate of the transfer of the dry powder from the reservoir to the atomization device. . A method according to any one of the preceding claims, further comprising monitoring the backpressure of the filter during at least step e). further comprising stopping said spraying of said dry powder towards said inlet face of said filter when a predetermined back pressure of said filter is reached, optionally said predetermined back pressure being an absolute back pressure 9. The method of claim 8, wherein 8. The method of any one of claims 1 to 7, further comprising monitoring the back pressure of the filter during at least steps c) and e), preferably during at least steps c), d) and e). described method. 11. The method of claim 10, further comprising stopping the spraying of the dry powder toward the inlet face of the filter when a predetermined back pressure of the filter is reached. Said predetermined back pressure is a relative back pressure, optionally a first back pressure of said filter is measured in step c) before said dry powder is deposited on said porous structure, A second back pressure is measured in step e) while the dry powder is deposited within the porous structure, wherein the atomization of the dry powder is such that the second back pressure is less than the first back pressure. 12. The method of claim 11, stopped when a predetermined percentage is reached. In step d), further comprising injecting said dry powder from said reservoir, optionally comprising gravimetrically feeding said dry powder to an injection device, optionally said injecting comprising: A method according to any one of claims 1 to 12, wherein a loss-in-weight feeder is used. An apparatus for treating a filter for filtering particulate matter from an exhaust gas, comprising:
i) a reservoir for containing dry powder;
ii) a filter holder for holding a filter, said filter being of the type comprising a porous substrate having an inlet surface and an outlet surface, said inlet surface and said outlet surface being separated by a porous structure; a filter holder;
iii) a vacuum generator for establishing a primary gas flow through said porous structure of said filter during use by applying a pressure drop to said exit face of said filter;
iv) a transport device for transporting the dry powder from the reservoir towards the filter;
iv) a spray device for receiving the dry powder from the transport device and spraying the dry powder towards the inlet face of the filter;
v) a controller configured to control operation of at least said vacuum generator and said atomizing device. The controller is configured to control the transfer of the dry powder from the reservoir to the atomization device by the transport device independently of controlling the primary gas flow generated by the vacuum generator. and optionally, the controller is configured to control the spray of the dry powder towards the inlet face of the filter independently of controlling the primary gas flow. 15. The device according to 14. 4. The controller is configured to operate the vacuum generator to establish the primary gas flow before the dry powder is transferred to the atomization device and atomized toward the inlet surface. 16. Apparatus according to Item 14 or 15. said transport device and/or said atomizing device comprises a secondary gas flow generator separate from said vacuum generator for transferring said dry powder from said reservoir to said atomizing device; is arranged to control the secondary gas flow generator independently of the vacuum generator. 18. Apparatus according to claim 17, wherein said secondary gas flow generator comprises a compressed gas generator, preferably a compressed air generator, and optionally said atomizing device is a compressed air gun. independently of controlling the transport device and/or the spray device to control the velocity or mass flow rate of the dry powder sprayed toward the inlet face of the filter; Apparatus according to any one of claims 14 to 18, configured to control a vacuum generator to control the level of the pressure drop applied to the outlet face of the filter. Further comprising a pressure sensor, preferably a single pressure sensor, for monitoring the back pressure of said filter, said controller being arranged to receive an output from said pressure sensor, optionally said pressure sensor, preferably a single pressure sensor, The device according to any one of claims 14 to 19, wherein said single pressure sensor is arranged in said vacuum generator, preferably in a vacuum cone of said vacuum generator. 21. The apparatus of claim 20, wherein the controller is configured to stop the spraying of the dry powder toward the inlet face of the filter when a predetermined back pressure of the filter is reached. . The transport device comprises a conduit extending at least partially from the reservoir to the atomizing device, the atomizing device being a compressed air gun configured to fluidize the dry powder in at least a portion of the conduit. Apparatus according to any one of claims 14 to 21, comprising a compressed air supply. 11. The claim further comprising an injection device for injecting said dry powder from said reservoir, optionally said injection device being a gravimetric device, optionally said injection device being a loss-in-weight feeder. A device according to any one of claims 14-22. Said filter is arranged in said holder in a vertical orientation with said inlet face uppermost, optionally said spraying device is arranged vertically above said inlet face, preferably said spraying device A device according to any one of claims 14 to 23, wherein the direction is coaxial with the longitudinal axis of the filter, preferably the spray direction and the longitudinal axis coincide. A processed filter obtainable by the method of any one of claims 1-13.