Method and apparatus for coating a carrier

Patent metadata

Field	Value
Publication number	US-10441949-B2
Application number	US-55335904-A
Country	US
Kind code	B2
Filing date	Apr 16, 2004
Priority date	Apr 17, 2003
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

This invention relates to a method and a corresponding apparatus for coating open-pored bodies with at least one coating suspension. In particular, the coating suspension has solids and solutes in a liquid medium in a quantity in wet state which is to correspond to at least a required target quantity. The coating operation has a variation in the applied wet coating quantity from one body to the other. The method according to the invention is characterized by the steps of: coating the body with an actual quantity of the coating suspension, which is always larger than the required target quantity taking the variation of the coating operation into account, determining the difference between the actual quantity and the required target quantity, and reducing the difference between actual quantity and target quantity by removing still wet coating suspension.

First claim

What is claimed is:

1. A method for coating a plurality of ceramic honeycomb carrier bodies, comprising flow ducts or flow pores, with at least one coating suspension, wherein the coating suspension comprises solids in a liquid medium, in a quantity in a wet state that corresponds to at least a required target quantity, wherein the required target quantity is an amount necessary to coat the flow ducts or flow pores in order to achieve a target catalytic activity, and the coating operation includes a variation in an applied wet coating quantity from one body to the other, the method comprising, for each carrier body in a production run:
(a) placing a raw coating onto a body at a coating station by
(i) delivering a quantity of the coating suspension to the body at the coating station; and
(ii) removing an amount of surplus coating suspension by pumping or suction to leave a quantity of wet coating suspension on the body in the form of a raw coating, the raw coating being present in a quantity that is larger than the required target quantity;

(b) determining, after step (a)(ii) and prior to any further removal of coating suspension from the body, a differential quantity representing a difference between an actual quantity of the raw coating and the required target quantity, and
(c) reducing the difference between the actual quantity of raw coating and the target quantity by removing still wet coating suspension,
wherein the removal of surplus coating suspension performed in the raw coating step (a) is performed with a pressure and a duration that has been predetermined to yield, on average for the plurality of the carrier bodies coated, an overloaded raw coating comprising a wet coating suspension that is not less than 102% of the target quantity and not more than 105% of the target quantity, the amount of the overloaded raw coating being set to correspond to the sum of the target quantity plus the variation amount of the coating operation,
wherein the determination of the differential quantity in step (b) involves a determination of the actual quantity of raw coating suspension present on each body comprising weighing each body after coating step (a)(ii),
wherein reducing step (c) involves reducing the difference between the actual quantity of raw coating and the target quantity comprising application of a pressure or suction at an intensity, a duration, or both an intensity and a duration that is set with reference to the magnitude of the differential quantity, which differential quantity is determined based on the weighing of the body in step (b), in order to reduce the magnitude of the differential quantity of still wet coating suspension on the weighed body,
wherein the solids of the coating suspension comprises a support material and the liquid medium of the coating suspension comprises water, with the solids having a concentration between 20 and 65 wt.-% based on the total weight of the coating suspension,
wherein the removal of still wet coating suspension in step (c) is performed for a duration set within a range between 0.5 and 2 seconds at a pressure set within a range between 50 and 500 millibars, and
wherein the removal of still wet coating suspension in step (c) results, on average for the plurality of the carrier bodies coated in the production run, in an excessive final coating that is within 1% of the target quantity.

2. The method according to claim 1 , wherein suction is used in step (c) and the intensity, the duration, or both the intensity and the duration of the suction are set corresponding to the measured actual quantity of raw coating based on tabulated data established in preliminary tests prior to the coating operation.

3. The method according to claim 1 , wherein suction is used in step (c) and the duration, the intensity, or both the intensity and the duration of the suction are controlled in accordance with:
the values for the actual quantity of raw coating, the duration of suction, and/or the intensity of suction determined for one or more bodies coated prior to the current body; and
the associated reduction obtained in the difference between the actual quantity of raw coating and the target quantity in the one or more bodies.

4. The method according to claim 1 , wherein the removal of still wet coating suspension is effected by suction or blowing with compressed air.

5. The method according to claim 4 , wherein the reduction in the difference between the actual quantity of raw coating and the target quantity in step (c) is performed each time said difference exceeds a previously specified threshold value.

6. The method according to claim 1 , wherein steps (b) and (c) are run at least twice until the actual quantity of raw coating is within a previously specified tolerance range above the target quantity.

7. The method according to claim 6 , wherein suction during the second run, is applied to an end of the body that is opposite to an end at which suction was applied in a first run.

8. The method according to claim 6 , wherein the reduction in the difference between the actual quantity of raw coating and the target quantity in step (c) is performed each time said difference exceeds a previously specified threshold value, with said threshold value reduced after each run.

9. The method according to claim 1 , wherein the reduction in the difference between the actual quantity of raw coating and the target quantity in step (c) is repeated until the actual quantity of raw coating corresponds with the target quantity, with the exception that the reduction in step (c) is not repeated despite the actual quantity of raw coating not corresponding with the target quantity when the actual quantity is determined to be below a threshold value that is above the target quantity though which is predetermined to present a risk of yielding an actual quantity of raw coating that is below the target quantity upon the performance of a further reduction.

10. A method for coating a plurality of carrier bodies comprising flow ducts or flow pores, the method comprising, for each carrier body in a production run:
(a) weighing said carrier body to determine the weight of the uncoated carrier body;
(b) delivering a coating suspension to the carrier body;
(c) removing surplus coating suspension from said carrier body by pumping or suction to leave a quantity of wet coating suspension on the carrier body in the form of a raw coating that is present in a quantity greater than a desired target quantity for the carrier body;
(d) weighing said carrier body, after step (c) and prior to any further removal of coating suspension from the carrier body, to determine the weight of said raw coated carrier body;
(e) determining a differential quantity which is the difference between the quantity of raw coating on said carrier body and the desired target quantity of coating on said carrier body; and
(f) reducing the difference between the raw coating quantity and the desired target quantity by applying suction or pressure to still wet raw coating on the carrier body at an intensity, a duration, or both an intensity and a duration that is based on the magnitude of the differential quantity determined following weighing of the raw coated carrier body,
wherein the delivery step (b) and removal step (c) together yield, on average for the plurality of the carrier bodies coated, an overloaded raw coating comprising a wet coating suspension that is not less than 102% of the target quantity and not more than 105% of the target quantity, the amount of the overloaded raw coating being set to correspond to the sum of the target quantity plus a variation amount of the wet coating quantity applied among carrier bodies coated in the produ

Assignees

• Harris Michael
• Detterbeck Dieter
• Lox Egbert
• Kreuzer Thomas
• Umicore Ag & Co Kg

Inventors

• Harris Michael
• Detterbeck Dieter
• Lox Egbert
• Kreuzer Thomas

Classifications

• B01J37/0215 Primary

  Coating · CPC title

• B05D7/22

  to internal surfaces, e.g. of tubes · CPC title

• B05D3/0493

  using vacuum · CPC title

• B01J35/04 Primary

  Operations & Transport · mapped topic

• B01J35/57

  Honeycombs · CPC title