GB2087818A - Tank fluid transfer device - Google Patents

Abstract

The tank fluid transfer device of the invention is operable to transfer fluid back and forth between interconnected tanks particularly the stabilizing tanks of a ship. The device incorporates a gas pump (4) and valve means (11, 14), the valve means (11, 14) being arranged to direct gas alternately from a gas space in one tank (1 or 2) to a gas space in the other tank (2 or 1) or to isolate the pump (4) from both tanks (1, 2) and the tanks from one another. The transfer of gas and thus of liquid from one tank to the other is performed as a closed circuit. <IMAGE>

Description

SPECIFICATION Tank fluid transfer device The subject of this invention is a tank fluid transfer device having for its object the transfer of fluid back and forth between interconnected tanks. Such a transfer of fluid is required, for example, in a tank apparatus for stabilizing and heeling a ship. In such an installation spaced wing tanks in the ship are interconnected by a fluid transfer pipe or duct so that the fluid may be placed in one tank or the other in the correct quantity and at the correct time to supply the required stabilizing or heeling moment.

Methods of fluid transfer are well known. Most commonly a fluid pump is placed in the fluid transfer pipe, but this does not allow the free and rapid transfer of fluid that is required in order to stabilize the roll of the ship and is used mainly for correcting its angle of heel. Methods are also known whereby the transfer of fluid through a large open fluid duct is effected by introducing air into the sealed space above the fluid in one tank so that the air compresses and develops a pressure differential with the air above the fluid in the second tank, which is open to the atmosphere. The fluid then moves until such time as the pressure head of the fluid equals the pressure differential between the two air spaces.

This method allows the tank to be used for both stabilizing and heeling purposes but is inefficient since work must be done to compress the air, and this compressed air is lost to the atmosphere whenever the direction of flow is reversed.

It is an object of the present invention to provide a tank fluid transfer device which is in operation more efficient and less power consuming than known devices.

A fluid transfer device according to the invention incorporates two tanks closed to the atmosphere and interconnected to one another in a manner two permit the free movement of liquid between them, a gas pump and valve means operative according to its setting to direct gas from the pump to the one tank and draw gas from the other tank and simultaneously provide a one-way passage for free flow of gas from the tank from which the gas is being drawn to the tank to which gas is being pumped orto isolate the pump from both tanks and prevent flow of gas either way from one tank to the other.

In one form of the device the valve means comprises two valve devices ganged to one another to operate simultaneously and arranged to have three settings, in one setting both valve devices isolate the upper parts of the tanks from one another, in a second setting one valve device connects the upper part of the one tank to the outlet of the pump and the upper part of the othertankto the inlet of the pump and the other valve connects the upper part of said one tank with the other tank by way of a one-way valve which permits movement of gas in the direction only from said other tank to said one tank and in the third setting of which said one valve device connects the upper part of said other tank to the outlet of the pump and the upper part of said one tank to the inlet of the pump and the other valve connects the upper part of said other tank with said one tank by way of a one-way valve which permits movement of gas in the direction only from said one tank to said other tank.

Each tank may comprise several subsidiary tanks interconnected to one another so that there is provision for free flow of fluid between them.

The gas pump may be an air blower for example of the type known as a Roots blower or may be an air pump of conventional rotary or piston type.

The two valve devices may be rotary valves having rotary elements formed with valve passages. The passages constituting the two valve devices may be formed on the same rotary element or there may be two separate elements rigidly coupled to one another to rotate together. Alternatively the valve devices may be slide valves whereupon the passages constituting the two valve devices may be formed on the same sliding element. The elements of the two valve devices may be formed on a single valve element or may consist of two separate elements rigidly coupled to one another.

The valve devices arranged to connect the tanks selectively to the pump may be formed with a passage so arranged that when the valve devices are in their first setting the inlet and the outlet ports of the pump are connected to one another. There may be provided at the connection of each tank to the valve device a float valve operable to close said connection if the liquid level in the respective tank rises beyond a predetermined level. Each tank may be provided with a venting valve which may be solenoid operated.

A gas inlet valve may be provided in the inlet connection of the pump for access of gas from an external source of gas. The valve may be a one-way valve arranged to allow gas to flow into the inlet of the pump only. Where the gas to be used is atmospheric air said valve provides a connection open to the atmosphere.

A practical embodiment of the invention arranged as a stabilizing apparatus for a ship is illustrated in the accompanying diagrammatic drawing in which 1 and 2 denote starboard and port tanks connected by a permanently open duct 3. 4 denotes an air pump having an inlet port 5 and an outlet port 6.7 and 8 denote two valve devices constituting a valve means incorporating rotary valve elements 9 and 10 which are ganged to one another to move in unison. The valve elements 9 and 10 are movable by servomechanism sensitive to the appropriate movement of the ship. The valve element 9 is formed with passages 11, 12 and 13 and the valve element 10 is formed with passages 14 and 15.The tank 1 is connected to the valve 9 by a conduit 16 and the tank 2 is connected ro the valve 9 by a conduit 17. 18 denotes a conduit connecting the inlet 5 of the pump 2 to the valve 9. the conduit 18 incorporates a one-way air inlet valve 19 and silencers 20. The valve 10 is connected to the conduit 16 by a conduit 21 and is also connected to the conduit 17 by two conduits 22 and 23 containing one-way valves 24 and 25 providing passage in the direction only towards and from the valve 10 respectively. 26 denotes float valves in the tanks 1 and 2 and 27 denotes solenoid operated vent valves in the tanks 1 and 2 respectively.

In practice, when fluid transfer operations are to commence the solenoid operated vent valves 27 are closed and the pump 2 started with the valve means 9, 10 in the centre position so that the air from the pump outlet 6 is returned directly to the pump inlet 5 and the only work done by the pump is to overcome pipe losses in the circuit 9, 18.

To transfer fluid from the starboard tank 1 to the port tank 2 the valve means 9, 10 is rotated clockwise so that air from the pump 4 is directed to the starboard tank 1 and drawn from the porttank4. As the air is compressed into the starboard tank 1 the pump 4 will tend to create a suction at the air inlet 5 and draw in sufficient air through the valve 19 to maintain atmospheric pressure at the pump inletS.

When the transfer of fluid to the port tank 2 is complete the rotary valve means 9, 10 is centred and the air is locked in the port tank 2 at atmospheric pressure and in the starboard tank 1 at a pressure equal to atmospheric pressure plus the additional pressure head of the fluid in the tank 2. There is a net increase in the mass of air in the system and this increased mass of air is retained, effectively supercharging the system so that it operates henceforth at a mean pressure above atmospheric pressure.

To transfer the fluid back from the port tank 2 to the starboard tank 1 the valve means 9, 10 is rotated counter-clockwise so that the pump 4 now draws air at a high pressure from the starboard tank 1 and acting as a baffle delivers it at a lower pressure to the port tank 2. While the fluid level in the port tank 2 remains higher than that in the starboard tank 1 the pressure head will cause air to flow through the valve device 10 of the valve means 9, 10 from the starboard tank 1 to the port tank 2 throgh the circuit 21, 15, 23, 25, 17. When the fluid levels in the port and starboard tanks 1 and 2 become the same the air pressures in the two tanks will be equal, but above atmospheric pressure.Thereafter as the liquid level in the tank 2 drops below that in the tank 1 air will no longer flow through the valve device 10 and the pump 4 will now draw air from the starboard tank 1 and deliver it at a higher pressure to the port tank 2.

As air is drawn from the starboard tank 1 so the pressure in the tank will be reduced, but no extra air will be drawn into the system unless there is a requirement to develop a larger pressure differential than has hitherto been used.

On completion of the first action of fluid transfer the valve means 9, 10 is again centred and thereafter fluid transfers can be made as described without any further requirement to draw in and compress atmospheric air. The continued operation of the device is thus rather a matter of transferring already compressed airthan compressing air and then releasing it each time a movement of liquid is to take place.

The apparatus is thus economical and quiet in operation.

Claims (10)

1. A fluid transfer device incorporating two tanks closed to the atmosphere and interconnected to one another in a manner to permit the free movement of liquid between them, a gas pump and valve means operative according to its setting to direct gas from the pump to one tank and draw gas from the other tank and simultaneously provide a one-way passage for free flow of gas from the tank from which the gas is being drawn to the tank to which gas is being pumped or to isolate the pump from both tanks and prevent flow of gas either way from one tank to the other.

2. Afluid transfer device as claimed in claim 1 in which each tank comprises several separate spaced interconnected subsidiary tanks.

3. Afluid transfer device as claimed in claim 1 in which the valve means comprises two valve devices ganged to one another to operate simultaneously and arranged to have three settings, in one setting both valve devices isolate the upper parts of the tanks from one another, in a second setting one valve device connects the upper part of the one tank to the outlet of the pump and the upper part of the other tank to the inlet of the pump and the other valve connects the upper part of said one tank with the other tank by way of a one-way valve which permits movement of gas in the direction only only from said other tank to said one tank and in a third setting of which said one valve device connects the upper part of said other tank to the outlet of the pump and the upper part of said one tankto the inlet of the pump and the other valve connects the upper part of said other tank with said one tank by way of a one-way valve which permits movement of gas in the direction only from said one tank to said other tank.

4. A fluid transfer device as claimed in claim 3 in which the two valve devices are rotary valves, the passages constituting the two valve devices being formed on the same rotary element.

5. Afluid transfer device as claimed in claim 3 in which the valve devices are slide valves, the passages consituting the two valve devices being formed on the said sliding element.

6. Afluid transfer device as claimed in claim 3 in which the valve devices are formed with a passage so arranged that when the valve devices are in their first setting the inlet and the outlet ports of the pump are connected to one another.

7. Afluid transfer device as claimed in claim 3 incorporating a float valve arranged at the connection of each tank to the valve device and operable to close said connection if the liquid level in the respective tank rises beyond a predetermined level.

8. A fluid transfer device as claimed in claim 1 in which each tank is provided with a venting valve.

9. A fluid transfer device as claimed in claim 1 in which a gas inlet valve is provided in the inlet connection of the pump for access of gas from an external source of gas.

10. Afluid transfer device substantially as described with reference to the accompanying drawing.