Particle blast cleaning apparatus

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, wherein like numerals indicate the same elements throughout the views, an improved particle-blast cleaning apparatus 10 of the present invention is shown in FIG.
1.
In particular, cleaning system 10 is illustrated in the form it would most preferably take for use wherein the particulate media is formed from liquid carbon dioxide.
Such liquid carbon dioxide is stored in a storage chamber 29 at relatively high pressure (e.
g.
about 300 psig) prior to injection via inlet 21 into a pellet extrusion cylinder 22 at approximately atmospheric pressure where such liquid carbon dioxide passes into the solid stage.
Liquid carbon dioxide (CO.
sub.
2) is maintained at about 300 psi and about 0.
degree.
F.
(-18.
degree.
C.
) in storage chamber 29 prior to being injected via the inlet 21 into extrusion cylinder 22 which is maintained at approximately atmospheric pressure.
Due to the sudden drop in pressure, a portion of the liquid CO.
sub.
2 crystallizes from its liquid phase to a solid or "snow" phase.
The snowflakes are retained within extrusion cylinder 22 by screens (not shown) which cover the outlet 23 through which waste gas is discharged.
Upon collection of a predetermined amount of such snow within cylinder 22, a hydraulic ram 24 drives a piston forward within extrusion cylinder 22 to compress the snowflakes to a solid block, which in turn is extruded through a die in pelletizer 25.
The resulting solid CO.
sub.
2 pellets pass through pellet conduit 28 to diverter means 50.
During the initial start-up of the subject particle blast cleaning apparatus, extrusion cylinder 22 and pelletizer 25 must chill down to proper operating temperature (i.
e.
about -100.
degree.
F.
or -74.
degree.
C.
).
During this chill-down time, imperfect pellets often result which are preferably disposed of as opposed to being run through the entire apparatus.
It is for this reason that it is preferred that particle blast apparatus 10 include means 50 for diverting these imperfect pellets immediately outside of the apparatus