Flammable gas dilution

Patent metadata

Field	Value
Publication number	US-12397270-B2
Application number	US-202117995891-A
Country	US
Kind code	B2
Filing date	Apr 7, 2021
Priority date	Apr 16, 2020
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A flammable gas diluter includes: a dilution vessel comprising an outer envelope defining a longitudinal flow passage from an inlet to an outlet; at least one air inlet for directing a flow of air into the inlet of the diluter; and a flammable gas inlet arrangement. The dilution vessel has a plurality of gas flow directing formations arranged between the flammable gas inlet arrangement and the outlet, each being at a different position along a length of the dilution vessel. At least one of the plurality of gas flow formations is an inwardly directing gas flow formation for directing gas flow away from the outer envelope and at least one of the gas flow formations is an outwardly directing gas flow formation for directing gas flow towards the outer envelope.

First claim

The invention claimed is:

1. A flammable gas diluter for diluting a flow of flammable gas to a concentration below the flammability limit of said flammable gas, said diluter comprising:
a dilution vessel comprising an outer envelope defining a longitudinal flow passage from an inlet to an outlet;
at least one air inlet assembly for directing a flow of air into said inlet of said dilution vessel;
a flammable gas inlet arrangement comprising a plurality of apertures at least some being arranged at different distances from said outer envelope of said dilution vessel across a cross section of said dilution vessel towards said inlet end of said dilution vessel;
a plurality of gas flow directing formations arranged between said flammable gas inlet arrangement and said outlet, each being at a different position along a length of said dilution vessel; wherein
at least one of said plurality of gas flow formations is an inwardly directing gas flow formation for directing gas flow away from said outer envelope and at least one of said gas flow formations is an outwardly directing gas flow formation for directing gas flow towards said outer envelope; and
wherein said dilution vessel comprises a constricted portion, said flammable gas inlet arrangement being located within said constricted portion such that said air is accelerated prior to passing said flammable gas inlet.

2. The flammable gas diluter according to claim 1 , comprising at least one gas flow generator for pumping a flow of air into said air inlet assembly, said at least one gas flow generator being located upstream of said flammable gas inlet arrangement.

3. The flammable gas diluter according to claim 2 , comprising two gas flow generators configured to operate as operational and backup gas flow generators.

4. The flammable gas diluter according to claim 2 , wherein said at least one gas flow generator and dilution vessel are configured such that a speed of flow of said air at said flammable gas inlet arrangement is greater than a flame speed of flammable gas.

5. The flammable gas diluter according to claim 1 , wherein said flammable gas inlet arrangement is configured such that said apertures are facing away from said gas outlet.

6. The flammable gas diluter according to claim 5 , wherein said apertures of said flammable gas inlet arrangement are between 2 and 5 mm in diameter.

7. The flammable gas diluter according to claim 1 , wherein said flammable gas inlet arrangement comprises an outer ring channel and radial channels running from said outer ring channel towards a centre of said ring, said radial channels comprising said apertures.

8. The flammable gas diluter according to claim 1 , wherein said flammable gas comprises hydrogen.

9. The flammable gas diluter according to claim 1 , wherein said dilution vessel, flammable gas inlet arrangement and gas directing formations are formed from metal and are earthed.

10. The flammable gas diluter according to claim 1 , wherein said inwardly directing gas flow formation comprises a ring-like baffle projecting in from said outer envelope and said outwardly directing gas flow formation comprising a centrally located cone shaped baffle an apex of said cone facing said inlet of said dilution vessel.

11. The flammable gas diluter according to claim 1 , said dilution vessel comprising a volume of less than 70 litres, said flammable gas diluter being configured to dilute a flow of flammable gas of up to 1,000 standard litres per minute.

12. The flammable gas diluter according to claim 1 , said flammable gas diluter comprising a flammable gas sampler adjacent to said outlet, said flammable gas sampler being in fluid communication with a flammable gas sensor, said flammable gas diluter further comprising control circuitry for inhibiting a flow of flammable gas to said diluter in response to said flammable gas sensor indicating a concentration of flammable gas above a predetermined level.

13. A vacuum pumping system for evacuating at least one vacuum chamber in a semiconductor processing tool, said vacuum pumping system comprising:
a plurality of vacuum pumps for evacuating said at least one vacuum chamber; and
an abatement system for receiving an exhaust from at least one of said at least one vacuum chamber, wherein said abatement system comprises a flammable gas diluter according to claim 1 .

14. The vacuum pumping system according to claim 13 , wherein said semiconductor processing tool comprises an extreme ultraviolet lithography tool and said flammable gas comprises hydrogen.

15. The vacuum pumping system according to claim 13 , further comprising a housing for housing said plurality of pumps; and
a vacuum system air flow generator configured to cause an air flow to flow through said housing to an air flow duct;
said air flow duct being in fluid communication with said at least one air inlet assembly for supplying said air to said flammable gas diluter.

Assignees

• Edwards Ltd

Inventors

• Greenwood Joanne Rachel
• Rechert Hans
• Knight Gary
• Galtry Michael

Classifications

• G03F7/70841

  Constructional issues related to vacuum environment, e.g. load-lock chamber · CPC title

• B01F35/2211

  Amount of delivered fluid during a period · CPC title

• B01F25/3131

  with additional mixing means other than injector mixers, e.g. screens, baffles or rotating elements · CPC title

• G03F7/708

  Construction of apparatus, e.g. environment aspects, hygiene aspects or materials · CPC title

• B01F35/2202

  Controlling the mixing process by feed-back, i.e. a measured parameter of the mixture is measured, compared with the set-value and the feed values are corrected · CPC title