Method and system for cleaning a surface with CO.sub.2 pellets that are delivered through a temperature controlled conduit

A system for cleaning a surface comprising:

• forming means forming carbon dioxide pellets;
• collecting means for collecting said pellets;
• supply means for supplying pressurized air;
• introducing means for introducing said pellets from said collecting means into a stream of high pressure air supplied by said supplying means;
• a conduit having opposing ends, said conduit connected at one end to said introducing means for receipt of said pellets and said pressurized air;
• a high pressure nozzle connected to the opposing end of said conduit;
• cooling means for cooling said high pressure air;
• and
• a control means comprising means for monitoring the temperature in the interior of said conduit, and means responsive to signals from said temperature monitoring means for controlling said cooling means to maintain a predetermined temperature of about -120.degree. F. of said high pressure air.

A method for cleaning a surface, comprising the steps of:

• forming pellets made of carbon dioxide;
• collecting the pellets in a hopper;
• providing a source of pressurized air;
• introducing the pressurized air into a feeder;
• introducing the pellets from the hopper into the feeder to combine the pellets and the pressurized air;
• maintaining the temperature of the pressurized air at a predetermined temperature level comprising the steps of:
• measuring the temperature of the pressurized air;
• and
• controlling the introduction of a coolant into the pressurized air in correspondence with the temperature of the pressurized air, to maintain the temperature below the sublimation point of carbon dioxide;
• and
• propelling the pellets onto a surface to be cleaned.