Apparatus and method to control deflagration of gases

• US 5,495,893 A
• Filed: 05/10/1994
• Issued: 03/05/1996
• Est. Priority Date: 05/10/1994
• Status: Expired due to Fees

• Current Assignee: FWM Technologies, LLC
• Original Assignee: ADA Technologies, Inc.
• Inventors: Butz, James R., Roberts, Daryl
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): HOGE, GARY CHAPMAN
• Application Number:
  US08/240,271
• Time in Patent Office: 665 Days
• Field of Search: 169/37, 169/46, 239/423, 239/594, 239/499, 137/896, 137/602, 261/78.2
• US Class Current: 169/37
• CPC Class Codes: A62C 31/03 adjustable, e.g. from spray to jet or vice versa
• CPC Class Codes: A62C 99/0072 using sprayed or atomised water
• CPC Class Codes: B05B 7/0012 Apparatus for achieving spraying before discharge from the apparatus
• CPC Class Codes: Y10T 137/87652 With means to promote mixing or combining of plural fluids

Abstract

One aspect of the present invention discloses a deflagration suppression system, which is particularly applicable to deflagrations involving combustible gases. The deflagration suppressant in the system is typically water which is dispersed in the combustible gas as a stream of droplets having a Sauter mean Diameter of no more than about 80 microns. The system can include a combustible substance detector to detect potentially explosive concentrations of a combustible substance, such as the combustible gas, before the onset of a deflagration.

Another aspect of the subject invention discloses a liquid atomizing device which is particularly applicable to the deflagration suppression system. The liquid atomizing device atomizes the liquid in a carrier gas and the liquid droplets are further decreased in size by increasing the velocity of the droplets to a supersonic velocity.

Claims

1. In a system for suppressing an exothermic reaction in a defined region in response to a signal generated by a sensing device, an apparatus for dispersing a stream of liquid droplets in the defined region comprising:

means for contacting a gas with a liquid to form a fluid;

a channel communicating with and extending radially outward from the contacting means, wherein the cross-sectional area of the channel at a first radial distance from the contacting means is more than the channel cross-sectional area at a second radial distance from the contacting means, the first radial distance being less than the second radial distance;

whereby the fluid is accelerated as it passes through the channel and

an outlet at the outer perimeter of the channel, said outlet having a cross-sectional area at a third radial distance from the contacting means that is less than the outlet cross-sectional area at a fourth radial distance from the contacting means, the third radial distance being less than the fourth radial distance, wherein the liquid has a supersonic velocity in at least one of the channel and the outlet and the outlet disperses a plurality of liquid droplets outward from the device.

2. The apparatus, as claimed in claim 1, wherein:

the outlet extends substantially the length of the outer perimeter such that the plurality of liquid droplets are dispersed radially outward from the device.

3. The apparatus, as claimed in claim 1, wherein:

the gas is generated by combusting a propellant selected from the group consisting of lead azide, sodium azide, and mixtures thereof.

4. The apparatus, as claimed in claim 1, wherein the contacting means comprises:

a porous surface for introducing one of the gas and liquid into the other of the gas and liquid.

5. The apparatus, as claimed in claim 4, wherein:

the average pore size of the porous surface ranges from about 1 to about 20 microns.

6. The apparatus, as claimed in claim 4, wherein:

the mass ratio of the gas to the liquid in the fluid adjacent to the porous surface is no more than about 0.25.

7. The apparatus, as claimed in claim 1, wherein:

the contacting means comprises a first conduit for transporting the gas, and a second conduit for transporting the liquid, an output of the first conduit being located inside of the second conduit, the output including a porous surface for contacting the liquid with the gas as the liquid moves past the porous surface.

8. The apparatus, as claimed in claim 7, wherein:

the first conduit extends through the channel and is positioned transverse to the channel; and

further comprising;

a liquid source located above the channel; and

a gas source located below the channel.

9. The apparatus, as claimed in claim 7, wherein:

the channel has a larger cross-sectional area than the area between the first and second conduit, such that, when the fluid enters the channel, the liquid forms a plurality of droplets suspended in the gas.

10. The apparatus, as claimed in claim 7, wherein:

the fluid in the area between said first and second conduits is from about 20 to about 70 percent by volume gas and the fluid in the channel is from about 50 to about 95 percent by volume gas.

11. The apparatus, as claimed in claim 1, wherein:

the maximum pressure of the fluid in the outlet is no more than about 53% of the maximum pressure of the fluid in the channel.

12. The apparatus, as claimed in claim 1, wherein:

the fluid has a supersonic velocity at a first location along the outlet and a sonic velocity at a second location along the outlet that is downstream of the first location.

13. The apparatus, as claimed in claim 1, wherein the dispersing means apparatus comprises:

two elongated coaxial disks forming an inner space there between, the inner space containing the channel and outlet with the contacting means being located along the axis of the elongated coaxial disks and positioned transverse to the channel, the elongated coaxial disks dispersing the fluid from a plurality of locations around the periphery of the elongated coaxial disks.

14. The apparatus, as claimed in claim 1, wherein:

the channel is tapered between the first radial distance and second radial distance.

15. The apparatus, as claimed in claim 1, wherein:

the outlet is tapered between the third radial distance and the fourth radial distance.

16. In a system for suppressing an exothermic reaction in a defined region in response to a signal generated by a sensing device, an apparatus for dispersing a stream of liquid droplets in the defined region comprising:

means for contacting a gas with a liquid to form a fluid;

a channel communicating with the contacting means, wherein the channel has a cross sectional area that decreases in the direction of fluid flow such that the velocity of said fluid in a portion of the channel is sonic; and

an outlet from the channel, wherein the outlet has a cross sectional area that increases in the direction of fluid flow such that the velocity of the fluid in a first portion of the outlet is supersonic and in a second portion is sonic, the outlet disperses a plurality of liquid droplets with the decrease in fluid velocity from supersonic to sonic decreasing the Sauter Mean Diameter of the liquid droplets exiting the outlet.