Refrigeration – Cryogenic treatment of gas or gas mixture – Solidification
Reexamination Certificate
2001-10-30
2002-09-03
Capossela, Ronald (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Solidification
Reexamination Certificate
active
06442968
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lightweight, highly mobile and efficient apparatus for instantaneously producing a high volume of compacted, solid carbon dioxide (CO
2
) pellets. The apparatus utilizes liquid CO
2
that is discharged through nozzles and expanded to reach a triple point condition in which solid, liquid and gaseous forms of CO
2
can coexist and flash to a mixture of CO
2
in a gaseous phase and particles of snow in a process well known in the art. The gaseous CO
2
is discharged into atmosphere or recovered for converting back to liquid by a vacuum recovery system or for use in extinguishing fire. The snow particles are aggregated into larger snowflakes which are compressed into pellets by an eccentrically supported rotor having radially movable vanes or blades mounted in radial slots in the rotor. The rotor and blades form circumferentially moving pockets associated with the interior surface of a partial rotor housing to compress the flakes into pellets as the volume of the pockets reduce as the rotor and blades rotate to a point of pellet discharge. The blades include slots extending to their outer edges which receive dividers rigidly mounted on the partial housing to divide the elongated pockets along the length of the rotor, housing and adjacent blades into smaller pockets to form smaller pellets. The smaller pellets are discharged from the partial rotor housing into an air lock which includes a housing and bladed rotor to convey the pellets to a discharge that is isolated from the pellet compression structure. The air lock includes an air discharge for the pellets to facilitate conveyance of the pellets to a point of use, such as the site of a fire in order to extinguish the fire.
2. Description of the Prior Art
The formation of CO
2
pellets from CO
2
snow is well known. Such pellets have been used for various purposes such as abrasive blasting when projected against a surface, conveying materials, neutralizing harmful substances in ambient air, quick freezing foods or other materials and the like.
The following U.S. patents disclose various uses of liquid CO
2
including apparatuses to form CO
2
pellets from liquid CO
2
.
U.S. Pat. No. 4,033,736
U.S. Pat. No. 4,389,820
U.S. Pat. No. 4,977,910
U.S. Pat. No. 5,355,962
U.S. Pat. No. 5,419,138
While certain of the prior patents disclose apparatuses for forming CO
2
pellets, the operational characteristics including slow start up, low production volume and structural details including large heavy components and power requirements for operation have restricted the use of CO
2
pellets for various uses.
For example, in U.S. Pat. No. 4,033,736, the impeller
80
is eccentrically mounted with respect to the housing
30
. Snow is formed from liquid CO
2
between the housing and impeller. When the impeller rotates, the snow is displaced radially through the extrusion passageways
52
in which the snow is compacted essentially by the reaction of springs
76
. In the present invention, the snow is compressed as it moves circumferentially between the rotor and the housing in the pockets formed by the housing, rotor and radially movable blades on the rotor as the pockets move circumferentially and reduce in volume due to the eccentric relationship of the rotor and housing.
U.S. Pat. No. 5,419,138 discloses the use of a hydraulic ram to compact CO
2
snow into pellets and discusses the development of prior apparatuses for producing CO
2
pellets and snow, the uses of such pellets and snow and the operational parameters of the prior art. The production volume of the apparatus is low and the start up time is long. Also, the structure is heavy and requires substantial power to operate.
In contrast, the apparatus of the present invention provides instantaneous, high volume production of high density solid CO
2
pellets and requires a small power input to produce pellets “on the spot” where such pellets are desired to suppress fires, reduce pollution and other various uses.
SUMMARY OF THE INVENTION
Gaseous carbon dioxide with or without snow particles has been used to suppress fires, especially under certain hazardous conditions, for many years. Until the development of halon systems, CO
2
was the only gaseous fire suppressant to effectively suppress fires of most materials with the exception of certain active metals and material containing their own oxygen source. Gaseous carbon dioxide is a desirable fire suppressant since it is not combustible, does not produce its own products of decomposition, provides its own pressurization for discharge from a storage container thereby eliminating the need for additional pressurization, leaves no residue thereby precluding the need of agent cleanup, relatively nonreactive with most materials, provides three dimensional protection because it is a gas under ambient conditions, is electrically nonconductive and can be used in the presence of energized electrical equipment. However, the use of gaseous CO
2
has been somewhat restricted as a fire suppressant or extinguisher due to the inability of delivering gaseous CO
2
to the site of a fire for distances much greater than 10 to 15 feet. Also, prior art devices do not produce sufficiently high volumes of CO
2
pellets that can be delivered long distances to effectively fight fires and pollution.
Halon based systems are being phased out due to regulations of the Environmental Protection Agency (EPA) mandating phase out of ozone depleting substances. Carbon dioxide is considered an alternative technology and this invention provides for the use of CO
2
as a replacement for halon and other ozone depleting substances which may harm the environment such as various foaming agents and the like.
It is an object of the present invention to provide an apparatus for instantaneously producing a high volume of high density solid carbon dioxide pellets from pressurized liquid carbon dioxide utilizing a relatively small, lightweight structure which is highly mobile. One embodiment of the invention has a total weight less than approximately 100 pounds, a height of approximately 30 inches and a depth and width of approximately 6 to 12 inches and powered by a small horsepower electric motor. The above dimensions may vary depending on the output desired. Alternatively, the unit can be powered by a gasoline or diesel powered engine of small horsepower. The above embodiment is capable of producing about 600 to 800 pounds of CO
2
pellets per hour depending upon the size of the components and the rotational speed of a rotor. The apparatus has a startup time of approximately 3 seconds thereby providing a very effective and inexpensive and rapidly activated fire suppressant system.
Another object of the invention is to provide an apparatus for producing carbon dioxide pellets in accordance with the present invention and the preceding object which includes a manifold receiving pressurized liquid carbon dioxide that is discharged through a plurality of nozzles into square expansion tubes in which the liquid carbon dioxide is transformed into a mixture of gaseous carbon dioxide and snow particles. The gaseous carbon dioxide is vented to atmosphere or discharged into a vapor recovery system. The snow particles formed in the tubes by the expanding CO
2
are aggregated in the pockets of a rotor system and compressed into solid carbon dioxide pellets.
A further object of the invention is to provide an apparatus for producing solid carbon dioxide pellets in accordance with the preceding objects in which the structure for compressing aggregated snow particles into pellets includes a partial generally cylindrical housing having a cylindrical rotor journalled therein with the rotational axis of the rotor being eccentric to the center of curvature of the partial cylindrical housing. The rotor includes radial slots receiving radially moveable vanes or blades having outer edges which are maintained in close contact with the interior of the partial cylindrical housing to form a plurality of closed pockets except fo
Elias Marc C.
Proni Oscar
Capossela Ronald
Elias Albert S.
Jacobson & Holman PLLC
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