| 摘要 |
PURPOSE:To cool a radiant heat shielding plate requiring no power in ordinary circumstances, and to make it possible to continuously precool the shielding plate while the powder is being economized by a method wherein a liquid nitrogen vessel, a refrigerant feeding tube, a regrigerant recovering tube, a liquid injection/precooling tube and the like are provided in the title device. CONSTITUTION:A refrigerant is allowed to flow from a vessel 4 to a refrigerant feeding tube 5 utilizing the difference of density between the vaporized refrigerant and liquefied refrigerant in a piping and the weight of liquid nitrogen 3 itself which is collected in a liquid nitrogen vessel 4 when a normal cooling operation is conducted, the above-mentioned refrigerant reaches a radiant heat shielding plate 2, and it returns to the vessel 4 passing through a refrigerant recovering tube 6. Also, when a precooling operation is conducted, a pump is operated, and the refrigerant is forcedly press-fed toward the aperture part 8a of the connection box 8 of a liquid injection/precooling tube using forcedly circulating force. Accordingly, the refregerant is allowed to flow from the tube 10 to the tube 5 utilizing the difference in the speed and quantity of flow of the refrigerant, and besides, the refrigerant returns to the vessel 4 from the tube 6 through the plate 2. As a result, the phenomenon such as gas lock and oscillation caused by the backward flow and the like of the vaporized refrigerant can be prevented, the forced circulation of the refrigerant can be made possible, and the precooling time can also be cut down sharply. |
