Filtering gas from pelletized co{hd 2 {l snow

Claim 2

The method of making carbon dioxide pellets according to claim 2, wherein the snow in the chamber is compressed by movement of a ram in the chamber toward the perforate head.

Claim 3

The method of making carbon dioxide pellets according to claim 3, further comprising the step of interrupting the flashing of the liquid carbon dioxide during movement of the ram toward the perforate head.

Claim 4

Apparatus for making carbon dioxide pellets, comprising: a chamber adapted to confine carbon dioxide snow except at one end, means for flashing liquid carbon dioxide to cause carbon dioxide snow and gas to fill the chamber, means for venting carbon dioxide gas from said chamber, a snow and gas filter impervious to carbon dioxide snow and pervious to carbon dioxide gas, said filter being disposed between said means for flashing liquid carbon dioxide and said means for venting carbon dioxide gas to sepaRate said snow from said gas without reference to gravity and deposit the separated snow in said chamber, a perforate head at said one end of said chamber having at least one opening of substantially reduced cross section relative to the chamber, a ram reciprocable in said chamber toward and away from said head, and means for actuating said ram, the end of said ram terminating short of said opening to provide a gastight seal at said head composed of carbon dioxide snow compressed by the ram and thus prevent gaseous communication between the atmosphere and said chamber

Claim 5

Apparatus as claimed in claim 5, wherein said liquid carbon dioxide flashing means is adapted to flash liquid carbon dioxide directly into the chamber.

Claim 6

Apparatus as claimed in claim 6, wherein said filter is tubular and forms part of the chamber.

Claim 7

Apparatus as claimed in claim 7, wherein said tubular filter is composed of sintered metal. 9 Apparatus as claimed in claim 7, wherein the end of said ram has a recess terminating in a sharp peripheral edge.

Claim 8

Apparatus as claimed in claim 7, including first conduit means for supplying liquid to be flashed, second conduit means for venting the vapor, and means for defrosting the apparatus by passing vapor from said second conduit means through said first conduit means and into said chamber.

Claim 9

Apparatus as claimed in claim 5, wherein said liquid carbon dioxide flashing means comprises a valve assembly, said valve assembly having an orifice and a valve element adapted to be actuated to selectively open and close said orifice, and means for actuating said ram and said valve element in timed relationship.

Claim 10

Apparatus for making carbon dioxide pellets, comprising: a chamber adapted to confine carbon dioxide snow except for an opening of substantially reduced cross section relative to the chamber; means for flashing liquid carbon dioxide to cause carbon dioxide snow and gas to fill the chamber; means for venting carbon dioxide gas from the chamber, said means comprising a snow and gas filter impervious to carbon dioxide snow and pervious to carbon dioxide gas, said filter being disposed between said means for flashing liquid carbon dioxide and said means for venting carbon dioxide gas to separate said snow from said gas without reference to gravity and deposit the filtered snow in the chamber; and means for compressing the snow in the chamber and forcing a substantial portion of the compressed snow through said opening while forming a gastight seal from the remainder of the compressed snow at said opening.

Claim 11

Apparatus as claimed in claim 12, wherein said filter is composed of sintered metal.