GB893642A - Process and apparatus for preventing losses from storage vessels for volatile liquids - Google Patents

Abstract

<PICT:0893642/III/1> In a plant for preventing losses from storage vessels for volatile liquids, a storage vessel 10 containing a volatile liquid, e.g. a petroleum fraction, is connected to a liquid-ring pump 20 by a pipe 13 connected to the vapour, space of the vessel 10 and by a pipe 24 connected to the liquid space of the vessel. The pump 20, the construction of which is described in Specification 813,420, is driven by a motor 18 which is automatically operated by a pressure-sensitive switch 14 when the pressure in the vessel 10 rises to a predetermined value and is cut off by a pressure-sensitive switch 16 when the pressure in the vessel 10 is sufficiently low. The solenoid valve 22 permits liquid to flow from the vessel 10 to the pump 20 only when the motor 18 is in operation. The effect of the arrangement is that vapour withdrawn through the pipe 13 is compressed in the pump 20 and reabsorbed, at least in part, in the liquid fed to the pump through the pipe 24, the liquid containing reabsorbed vapour passing from the outlet 28 of the pump to the vessel 10 through a pipe 32 having a non-return valve 30. Unabsorbed vapour from the pump 20 passes through a pipe 36 to a storage tank 40 for use in repressurizing the vessel 10 when required. For this purpose the tank 40 communicates with the vessel 10 through a pipe 48 carrying a valve 52 which is responsive to the pressure in the vessel 10, to which it is connected by a pipe 56. Vapour may be discharged from the tank 40, if necessary, through a pipe 50, or additional gas for pressurizing the vessel 10 may be supplied through a pipe 58.