Catalytic thermal debind furnaces with feedback control

Patent metadata

Field	Value
Publication number	US-11988381-B2
Application number	US-202016897529-A
Country	US
Kind code	B2
Filing date	Jun 10, 2020
Priority date	Jun 12, 2019
Publication date	May 21, 2024
Grant date	May 21, 2024

Abstract

Apparatus and methods for debinding articles. The apparatus and methods may transform binder from furnace exhaust before the exhaust is discharged to the atmosphere. The apparatus may include a furnace retort and a reactor. The furnace retort may be configured to: exclude ambient air; and receive a carrier gas. The reactor may be configured to: receive from the retort (a) the carrier gas and (b) material removed in the retort from the article; and combust, at a temperature no greater than 750° C., the material. The material may be decomposed binder. The material may be hydrocarbon from binder that is pyrolyzed in the retort. The carrier gas may include gas that is nonflammable gas.

First claim

What is claimed is:

1. Apparatus for processing an article, the apparatus comprising:
a furnace retort configured to:
exclude ambient air; and
receive a carrier gas, said carrier gas consisting of a gas selected from an inert gas, a noble gas, and hydrogen gas; and

a reactor comprising an “oxi-cat” catalytic trap that is configured to:
receive, at an entry temperature at or above 200° C., from the retort the carrier gas and hydrocarbon pyrolyzed in the retort;
combust, at a temperature no greater than 750° C., the hydrocarbon; and

a control system that comprises a processor that is configured to:
receive from a sensor a first value of a characteristic that is responsive to a rate of a reaction in the reactor; and
determine a variance between the first value and a target;

transmit to a process control element a reactor input instruction corresponding to a reduction in the variance based on a stoichiometric relationship between the carrier gas and the hydrocarbon, wherein the processor is configured to adjust a carrier gas flow rate to which the pyrolytic debinding process is subjected.

2. The apparatus of claim 1 further comprising a channel configured to conduct the carrier gas and the hydrocarbon from the retort to the reactor; wherein, along the channel, no vessel configured to oxidize hydrocarbon in a reaction having a temperature greater than 750° C. is included.

3. The apparatus of claim 1 further comprising a channel configured to conduct the carrier gas and the hydrocarbon from the retort to the reactor, the channel including a fixture configured to receive oxygen-bearing gas from a dispenser.

4. The apparatus of claim 1 further comprising a channel configured to conduct the carrier gas and the hydrocarbon from the retort to the reactor.

5. The apparatus of claim 4 wherein:
the reactor includes a fixture configured to receive oxygen-bearing gas from a dispenser; and
the fixture is not part of the channel.

6. The apparatus of claim 1 , wherein the input is a hydrocarbon production rate in a pyrolytic debinding process in the retort.

7. The apparatus of claim 6 wherein the processor is configured to adjust a temperature ramp to which the pyrolytic debinding process is subjected.

8. The apparatus of claim 1 , wherein the input is a supply rate of oxygen-bearing gas to the reaction.

Assignees

• Markforged Inc

Inventors

• Chao Michelle
• Durand Keith
• Woodruff Rick Bryan
• Gallup Benjamin Hodsdon

Classifications

• F27D17/20

  Arrangements for treatment or cleaning of waste gases · CPC title

• F27D17/22

  for removing solid constituents · CPC title

• F23G7/065 Primary

  using gaseous or liquid fuel · CPC title

• B22F3/003

  Apparatus, e.g. furnaces (in general F27B) · CPC title

• F23G7/07

  in which combustion takes place in the presence of catalytic material · CPC title