| 摘要 |
812,998. Storing liquefied gases; reciprocating pumps; forcing liquids by gaseous pressure. UNION CARBIDE CORPORATION. Nov. 6, 1956 [Dec. 2, 1955], No. 33894/56. Classes 8(2), 102(1) and 102(2). A storage and pumping system for liquefied gas comprises a heat insulated tank for holding the liquified gas at normal storage pressure, a pump for withdrawing liquid from the tank and a pressure building means adapted to raise the pressure in the tank above the normal storage pressure in which the pump control means are arranged to render operative pressure control means which in response to the pressure within the tank control the flow of a pressure building gas to the tank to maintain the pressure within a higher pressure range during the pumping period. Three embodiments are described which are suitable for use with cold pumps. Pressure building is obtained by an evaporating coil 208 connected between the top and bottom of the tank S. Flow through the coil 208 is controlled by a solenoid operated valve 209 the solenoid of which is controlled by a pressure switch 211 subjected to the tank pressure, the switch 211 being in series with a switch 212 operated by the motor control circuit. In the second embodiment, Fig. 2 (not shown). the valve in the evaporating circuit is under the control of two pressure switches the lower pressure switch being by-passed when the pump circuit is energised. In the third embodiment, Fig. 4 (not shown), the evaporating circuit control valve is under the control of a pressure switch brought into circuit when the motor circuit is energised and the valve and pressure switch are by-passed by a low range pressure operated valve. The evaporating circuit also includes a relief valve under the control of two pressure switches one of which is operated in the high range and the other in the low range. In the second and third embodiments liquid may be withdrawn from the tank by the gaseous pressure only acting on the liquid. In a modification, Fig. 3 (not shown), the pressure building circuit comprises an external source of pressure gas which is fed to the upper part of the tank S through two pressure operated valves in parallel the higher pressure branch including a valve which is opened when the pumping circuit is energised. |
