Liquid-piston type slurry pumping system

Claim 2

A liquid-piston type slurry pumping system operable in a slurry pipe line, said system comprising: a pump unit of a type continuously delivering a pressurized operating fluid which is of a specific gravity different from that of slurry to be pumped and is substantially immiscible with, insoluble in, and unreactive with the slurry; at least two valve boxes each including a suction valve and a discharge valve connected respectively to the pipe line; at least a pair of liquid containers connected respectively to the valve boxes; passage means connecting said containers and said pump unit; means for changing over said passages between the pump unit and the liquid containers, thereby to introduce the operating fluid into the liquid containers alternately; detecting means provided in each of the containers for detecting any displacement in excess of a predetermined value of a boundary surface formed between the fluid and the slurry coexisting in the containers; a controller for controlling the operation of the fluid-passage changeover means in response to signals from said detecting means, whereby the pulsations of the boundary surfaces in the containers are controlled in response to the detected results of the detecting means, and the operation of the pumping system is thereby stabilized; and a piston-cylinder device provided between the liquid containers and said fluid-passage changeover means, said device being comprised of means isolating the operating fluid from the slurry but transmitting hydraulic displacement between the operating fluid and the slurry, first and third cylinders respectively including pistons connected together operatively, and second and fourth cylinders respectively including pistons connected together operatively, the first side of the piston in the first cylinder and the second side of the piston in the second cylinder being connected to a passage in said fluid passages changing over means, the second side of the piston in the first cylinder and the first side of the piston in the second cylinder being connected to another passage in said fluid passages changing over means, the first side of the piston in the third cylinder and the second side of the piston in the fourth cylinder being connected to one liquid container, the second side of the piston in the third cylinder and the first side of the piston in the fourth cylinder being connected to the other liquid container, said operating fluid occupying both sides of each of the first and second cylinders, and the interiors of the third and fourth cylinders being occupied by an additional operating fluid which forms a boundary surface in each of the liquid containers between itself and the slurry.

Claim 3

a liquid-piston type slurry pumping system as set forth in claim 1 wherein said operating fluid used in the pumping unit is a gas such as air or steam.

Claim 4

In a liquid-piston type slurry pumping system for conducting a slurry through a pipeline and including pumping means having a suction side and a pressure side and continuously delivering a pressurized operating fluid having a specific gravity lower than that of the slurry and substantially immiscible with, insoluble in, and unreactive with the slurry, at least one pair of valve boxes connected, respectively, to the pipeline in parallel relationship to each other and each including a suction valve and a discharge valve, at leAst one pair of liquid containers respectively connected to said valve boxes, a boundary surface formed in each of said containers between operating fluid and slurry contained therein, passage means connecting said containers and said pumping means, means for changing over said passage means to alternatively introduce the operating fluid delivered from said pumping means into one of said containers, detector means for detecting a level of said boundary surface in each of said containers, and control means for controlling the operation of said changeover means in response to detection of the level by said detecting means, the improvements comprising: said detector means for each container being comprised of means for detecting a displacement of said boundary surface beyond a predetermined raised level in the container, each container being connected at an upper portion thereof to said passage means; said changover means being comprised of a single sliding changeover valve movable between a first position in which a first of said containers is connected to the suction side of said pumping means and a second container is connected to the pressure side and a second position in which said first container is connected to the pressure side of said pumping means and said second container is connected to the suction side of said pumping means; said control means being adapted to shift said changeover valve from said first position to said second position when said boundary surface in said first container reaches said predetermined raised level, and from said second position to said first position when said boundary surface in said second container reaches said predetermined raised level; a piston-cylinder device interposed between said liquid containers and said changeover valve, said piston-cylinder device separating said passage means into a first section containing a first operating fluid adapted to be pumped by said pumping means and a second section containing a second operating fluid, said boundary surface in each container being formed between said second operating fluid and the slurry, said piston-cylinder device isolating the first operating fluid from the slurry but transmitting hydraulic displacement between said first operating fluid and the slurry, said piston-cylinder device being comprised of first and third cylinders each including a piston, said respective pistons operatively connected together, and second and fourth cylinders each including a piston, said pistons being operatively connected together, said pistons of each cylinder dividing said cylinder into two regions, said first and second cylinders being connected to a first common passage adapted to be selectively connected to the pressure and suction sides of said pumping means by said changeover valve, said first and second cylinders being connected to a second common passage adapted to be selectively connected to the suction and pressure sides of said pumping means by said changeover valve, said first and second common passages respectively communicating with different regions in said first and second cylinders, said third and fourth cylinders being connected to said first and second liquid containers in different regions thereof, said first operating fluid occupying both regions of said first and second cylinders, both regions of said third and fourth cylinders being occupied by said second operating fluid.

Claim 5

In a liquid-piston type slurry pumping system for conducting a slurry through a pipeline and including pumping means having a suction side and a pressure side and continuously delivering a pressurized operating fluid having a specific gravity lower than that of the slurry and substantially immiscible with, insoluble in, and unreactive with the slurry, at least one pair of valve boxes connected, respectively, to the pipeline in parallel relationship to each other and each including a suction valve and a discharge valve, at leAst one pair of liquid containers respectively connected to said valve boxes, a boundary surface formed in each of said containers between operating fluid and slurry contained therein, passage means connecting said containers and said pumping means, means for changing over said passage means to alternatively introduce the operating fluid delivered from said pumping means into one of said containers, detector means for detecting a level of said boundary surface in each of said containers, and control means for controlling the operation of said changeover means in response to detection of the level by said detecting means, the improvements comprising: said detector means for each container being comprised of means for detecting a displacement of said boundary surface beyond a predetermined raised level in the container, each container being connected at an upper portion thereof to said passage means; said changover means being comprised of a single sliding changeover valve movable between a first position in which a first of said containers is connected to the suction side of said pumping means and a second container is connected to the pressure side and a second position in which said first container is connected to the pressure side of said pumping means and said second container is connected to the suction side of said pumping means; said control means being adapted to shift said changeover valve from said first position to said second position when said boundary surface in said first container reaches said predetermined raised level, and from said second position to said first position when said boundary surface in said second container reaches said predetermined raised level; a piston-cylinder device interposed between said liquid containers and said changeover valve, said piston-cylinder device separating said passage means into a first section containing a first operating fluid adapted to be pumped by said pumping means and a second section containing a second operating fluid, said boundary surface in each container being formed between said second operating fluid and the slurry, said piston-cylinder device isolating the first operating fluid from the slurry but transmitting hydraulic displacement between said first operating fluid and the slurry, said piston-cylinder device being comprised of first and third cylinders each including a piston, said respective pistons operatively connected together, and second and fourth cylinders each including a piston, said pistons being operatively connected together, said pistons of each cylinder dividing said cylinder into two regions, said first and second cylinders being connected to a first common passage adapted to be selectively connected to the pressure and suction sides of said pumping means by said changeover valve, said first and second cylinders being connected to a second common passage adapted to be selectively connected to the suction and pressure sides of said pumping means by said changeover valve, said first and second common passages respectively communicating with different regions in said first and second cylinders, said third and fourth cylinders being connected to said first and second liquid containers in different regions thereof, said first operating fluid occupying both regions of said first and second cylinders, both regions of said third and fourth cylinders being occupied by said second operating fluid.

Claim 6

The improved liquid-piston type slurry pumping system as set forth in claim 3, wherein said first operating fluid is a gas such as air or steam.