JPS61249512A - Slurry force feeder for solid and liquid separation - Google Patents

Abstract

PURPOSE:To freely regulate the rating of the titled slurry force feeder by connecting the suction and discharge chambers of a liq. discharge pump, one and the other pressurized chamber of a liq. feed pump and an oil tank to the liq.-operated chamber of a free-piston pump. CONSTITUTION:Actuating oil is filled in a pressurized chamber 45 on one side of a liq. feed pump 39 to temporarily return the actuating oil in the liq.-operated chamber 32 of a free-piston pump 14 to the feed and discharge chamber 48 of a liq. discharge pump 42. The actuating oil is supplied and sent into the liq.-operated chamber 32 of the free-piston pump 14 from a suction pipe 34 through a pipe 46, a change-over valve 36 and a flexible hose. Furthermore, a slurry from a slurry tank 13 which has been sucked and filled in a slurry chamber 33 is pressurized by pressing a free piston 30 and supplied to a filter press 15 from a line 25 while preventing the return of the slurry to the slurry tank 13 by a check valve 22.

Description

[Detailed Description of the Invention] Industrial Application Fields The disclosed technology is applicable to solid-liquid separators such as filter presses,
This field belongs to the structure of devices that pump slurry such as sludge, and its control technology.

<Summary of the gist> The invention of this application provides a solid-liquid separator that is connected to an oil tank when supplying a predetermined can of slurry from a slurry tank to a solid-liquid separator such as a filter press that obtains a cake from slurry. In a slurry pumping device that supplies working oil by operating a slurry supply pump, the hydraulic chamber of the free piston type pump is connected to the supply/discharge pump through the switching operation of a switching valve. This invention relates to a slurry pumping device for solid-liquid separation, which pumps slurry to a solid-liquid separation device by the operation of a type pump, and in particular, the invention relates to a slurry pumping device for solid-liquid separation, in which the slurry is pumped to a solid-liquid separation device by the operation of a pump. It consists of a liquid pump and a drain pump, and the drain pump is a dedicated pump that sucks working oil from the hydraulic pressure chamber of the free piston pump into its suction and discharge chamber and returns it to the oil tank. One of the pressurizing chambers of the liquid pump is connected to the oil tank via a switching valve to perform pressurizing operation only, and the other pressurizing chamber receives operating oil from the oil tank via the switching valve. Cooled working oil is forced into the hydraulic chamber of the piston type pump, and in the free piston type pump, the free piston moves back and forth to maintain a predetermined posture when discharging the working oil. This invention relates to a slurry pumping device for solid-liquid separation, in which a rod is fixed to a free piston so as to be slidable between the front and rear lids of a casing of a free piston pump so that the pump can be operated.

<Prior art> As is well known, domestic wastewater, industrial wastewater, etc. are separated into solid and liquid using a filter press, etc., water is returned to the water system as clear water, and sludge such as cake is disposed of by incineration, etc. In recent years, due to the large scale of industry and the increasing demand for domestic water, the gap between domestic wastewater and industrial wastewater has become increasingly large.As a result, solid-liquid separation equipment for slurry in wastewater has become a large-scale plant. As a result, there is a strong desire for highly accurate control and management to ensure accurate operation, and failure to do so may lead to large-scale secondary pollution.

Therefore, as a solid-liquid separator for slurry, the fifth
As schematically shown in the figure, the slurry 2 in the slurry tank 1 is supplied via a pipe 3 to a solid-liquid separator 6 such as a fill-press by a pump 4 via a valve 5 to produce clear water and sludge such as cake. It is designed to be processed separately.

Thus, the slurry 2 is fed under pressure to the solid-liquid separator 6 i!
The pump 4 used as i Plunger pumps and the like cannot meet these needs, and diaphragm pumps and the like, which can handle large output and large volumes, are being used.

Therefore, the aspect of such large-capacity batch processing and flow processing will be briefly explained with reference to FIG. The diaphragm pump 7
A switching valve 10 is interposed in the connection pipe 9 between the hydraulic fluid tank 8 that supplies hydraulic fluid to the diaphragm pump 7 and the hydraulic fluid is supplied to the diaphragm pump 7 by a pump 11 such as a plunger pump or vane pump. Feedback was provided from the diaphragm pump 7 to the hydraulic fluid tank 8.

<Problems to be Solved by the Invention> As mentioned above, as the amount of slurry processed has become extremely large in recent years, the capacity and output of the diaphragm pump 7 have also increased, resulting in an abnormal output state. This causes damage to the diaphragm pump 1, resulting in a problem that the plant cannot operate smoothly.

However, in the conventional slurry processing plant, the control of pressure-feeding the hydraulic fluid from the hydraulic fluid tank 8 to the diaphragm pump 7 by the pump 11 was performed by a simple pressure switch, etc., so that the upper and lower limits of the pressure switch If the detection operation of the diaphragm pump 7 unexpectedly becomes unstable or does not operate, there is a risk that the amount of working fluid from the pump 11 to the diaphragm pump 7 will become abnormally large, resulting in overpressure. If the device is constructed using a so-called high-grade detection mechanism such as electronic control, failures are likely to occur, and the more complicated the device is, the more difficult it becomes to control.

Furthermore, since there are the piping 9 and the switching valve 10, as well as flow control valves, check valves, relief valves (not shown), etc. between the hydraulic fluid tank 8 and the diaphragm pump 1, the energy when sucking and discharging the hydraulic fluid is reduced. is converted into thermal energy and the temperature of the working fluid tank 8 rises,
This has the drawback of causing inconveniences such as expansion of the hydraulic fluid, which also has the disadvantage of preventing the control device from operating accurately.

To deal with this, it is possible to manually switch the hydraulic fluid for the diaphragm pump 7, but this is an extremely primitive and inefficient process, and the above-mentioned unforeseen circumstances may occur. It has the disadvantage of being easy.

Furthermore, in order to operate a large-capacity diaphragm pump, the cycle of supplying and discharging hydraulic fluid such as oil to the hydraulic chamber is easy, but with a single diaphragm pump, the suction and discharge cycle is long, and the cooling There is a tendency to not match the cycle.

Although diaphragm pumps have the capacity to handle large volumes, they also have disadvantages in that the diaphragm itself is prone to fatigue, requires irregular maintenance, and is cumbersome to manage.

The purpose of the invention of this application is to solve the problems of the diaphragm pump of a slurry processing plant based on the above-mentioned prior art, which is a technical problem that can be operated at the rated value, can be freely adjusted, and can be easily managed and controlled. It is an object of the present invention to provide an excellent slurry pumping device for a solid-liquid separator that does not require much maintenance, does not cause failures, and is useful in the field of slurry treatment technology in the pollution treatment industry.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the invention of this application, which is summarized in the above-mentioned claims, provides a slurry pumping device attached to a solid-liquid separation device. The slurry chamber of the free piston pump is filled with slurry from the slurry tank.
When the switching valve is operated and working oil is supplied from the oil tank to one pressurizing chamber of the fluid supply pump via the oil pump, the working oil in the other pressurizing chamber is supplied to the free piston pump via the switching valve. The slurry is fed into the hydraulic pressure chamber and pressurizes the free piston, and the free piston supplies the filled slurry to a solid-liquid separator such as a filter press, and the solid-liquid separator operates in a predetermined manner to perform solid-liquid separation. The slurry is separated and solidified, and the clarified water is returned to the water system.When supplying the slurry again to the opened solid-liquid separator, the liquid supply pump is used to supply the slurry from the oil tank via the switching valve. An oil pump is used to supply working oil to the other pressurizing chamber, and the working oil in the pressurizing chamber on one side is returned to the oil tank via a switching valve, while being mechanically connected to the liquid supply pump. The suction and discharge chamber of the drain pump expands to generate negative pressure, and the working oil in the hydraulic pressure chamber of the free piston pump is sucked into the suction and discharge chamber of the drain pump through a switching valve installed in the passage. Therefore, the free piston in the free piston pump moves back to suck in and fill the slurry from the slurry tank, and during this time the free piston moves back and forth based on the shaft, which is loosely attached to the casing in the free piston pump. In the process of moving forward and backward in the direction, no differential pressure is generated before and after the free piston, so no slurry leaks to the free piston, and therefore no failure occurs, and the slurry suction and filling operation is not hindered in any way. By repeating this cycle, the free piston pump moves back and forth to repeatedly supply slurry from the slurry tank to the solid-liquid separator, and thus, the free piston pump moves back and forth to repeatedly supply slurry from the slurry tank to the solid-liquid separator. The working oil is once supplied to the pressurizing chamber via the pressurizing chamber of the liquid supply pump, and then is supplied into the hydraulic chamber of the free piston pump, and on the other hand, the working oil in the hydraulic chamber is drained. The oil is once discharged into the suction and discharge chamber of the pump and then returned to the oil tank. Therefore, the working oil in the hydraulic pressure chamber of the free piston pump is efficiently supplied and discharged by the supply pump. As for the oil tank, the discharged working oil from the hydraulic pressure chamber is not simultaneously mixed with the pumped oil in the oil tank, so that the cooled working oil is reliably pumped into the hydraulic pressure chamber of the free piston pump. This was achieved by taking technical measures to

<Embodiments - Configuration> Next, embodiments of the invention of this application will be described below based on the drawings of FIGS. 1 to 4.

In the embodiment shown in FIG. 1.2, 12 is a slurry pumping device for solid-liquid separation, which constitutes the gist of the invention of this application, and sucks and discharges slurry such as domestic wastewater from a slurry tank 13 via a free piston pump 14. The water is fed to a well-known filter press 15 as a chamber device and compressed to a predetermined degree, cake sludge is discharged to a predetermined value, and clear water is returned to the water system.

In the slurry tank 13, a liquid level switch 16 is provided to control the upper and lower limits of the operation of the stirring device 17 and the supply pump 18, and the supply pump 18 can accidentally - The tank 13 is of a lift type so as not to supply the slurry settling at the inner bottom to the free piston type pump 14, and the lift pressure feeding pipe 1
9, a valve 20, a three-way valve 21, a check valve 22, and a free piston pump 14 for supplying slurry. It is connected.

Furthermore, the free piston type pump 14 is connected to a well-known filter press 15 by a feeding pipe 25 via a drain plug 24.
It is connected to the.

The free piston type pump 14 is equipped with an upper limit pressure switch 26 and a lower limit pressure switch 27, and is also equipped with pressure gauges 28 and 28' connected to the pair of working chambers, and further includes: An initial oil filling port 29 is provided for air bleeding.

The free piston 30 installed in the free piston type pump 14 is slidably inserted into the casing in an axial watertight state, and its circumference is made of stainless steel or other material with sufficient sealing properties as shown in Fig. 2. A predetermined seal ring 31 having a diameter is interposed therebetween.

The number of seal rings 31 is determined in accordance with a design in which no differential pressure occurs between the front and rear pressures of the free piston 30.

One side of the free piston 30 is made into a pressure-feeding hydraulic chamber 32 with a variable capacity, and the other side is separated into a slurry chamber 33 with a variable capacity, which collects slurry from the slurry tank 13. The slurry is sucked and filled, and the slurry is pumped to the filter press 15 under high pressure.

Further, a suction pipe 34 and a discharge pipe 35 for oil as a working fluid are connected to the hydraulic pressure chamber 32.

And the suction pipe 34 of the free piston pump 14
is connected to the hydraulic fluid supply/drainage pump 3 via the switching valves 36 and 37.
The discharge pipe 3 of the free piston pump 14 is connected to the liquid supply pump 39 and the oil tank 40 forming the
5 is connected via a switching valve 41 to a drain pump 42, which is the other side of the supply/drain pump 38, and is also connected to the oil tank 40.

The liquid supply pump a9 and the liquid drainage pump 42 are
As shown in the figure, they are mechanically connected integrally by a connecting bracket 44 via rods 43 and 43 to operate synchronously, and a pressurizing chamber 45 on one side of the liquid supply pump 39 is The other pressurizing chamber 45' is connected to the switching valve 31 via a pipe 47.

On the other hand, the suction/discharge chamber 48 of the drain pump 42 is connected to the switching valve 47 via a pipe 49, and the air chamber 48' is opened to the atmosphere through an appropriate filter.

Further, the oil tank 40 is equipped with a strainer 5 as shown in the figure.
0 to the hydraulic pump 51, and the check valve 5
A pressure gauge 53 and a relief valve 5 are attached to the oil pipe having a pressure gauge 53 and a relief valve 5.
4 and is connected to the switching valve 37.

Incidentally, a fluxipul hose 55 is appropriately interposed in the middle of each of the suction pipe 34 and the discharge pipe 35.

<Example - Effects> In the above-described configuration, in the first step in which the slurry pumping device 12 is operated and the solid-liquid separator 14 sucks slurry from the slurry tank 13 and pumps it to the next stage filter press 15, First, in the switching process, the switching valve 36.3
7.41 is in the neutral state as shown in FIG.

When the control device (not shown) moves the switching valve 36 to the right in the figure, and the switching valves 37 and 41 shift from the neutral state to the left, the hydraulic oil from the oil tank 40 by the hydraulic pump 51 is Switching valve 31
, the check valve 52' is opened, and the liquid enters the pressurizing chamber 45 on the other side of the liquid supply pump 39 via the pipe 46.

The hydraulic oil moving to the switching valve 3G side opens the check valve 52, but is also forced into the pressurizing chamber 45 via the pipe 46.

Therefore, the piston of the liquid feed pump 39 normally moves the rod 43 to the right, and the piston of the drain pump 42 is moved to the right by the rod 43 via the connecting bracket 44, also integrally with the rod 43.

Therefore, the air in the air chamber 48' of the drain pump 42 is discharged to the atmosphere, and negative pressure is generated in the suction and discharge chamber 48, which functions to absorb the working oil described below. Since the valve 41 is normally moved to the left side, the suction/discharge chamber 48 and the drain pump 32 of the free piston pump 14 are connected to the discharge pipe 35 via the switching valve 41.

Also, at this time, the valve 20 is controlled via the control device (not shown).
is opened, and the supply pump 18 of the slurry tank 13 supplies slurry through the supply pipe 19 and the check valve 22 to the slurry chamber 33 of the free piston pump 14.

Therefore, an unbalanced state of pressure appears in the hydraulic pressure chamber 32 and the slurry chamber 33, which are separated by the free piston 30 in the free piston type pump 14, and therefore the free piston 30 is moved to the left side in the figure due to the differential pressure. The hydraulic oil in the hydraulic pressure chamber 32 passes through the flexible hose 55 via the discharge pipe 35, and is fed into the suction/discharge chamber 48 of the drain pump 42 via the switching valve 49 and the pipe 49.

During this time, the free piston 30 of the free piston pump 14 moves to the left in the figure, but the seal ring 31 of the free piston 30 prevents the slurry from entering the hydraulic chamber 32.

In this way, the hydraulic chamber 32 of the diaphragm pump 14
The working oil inside is temporarily returned to the suction/discharge chamber 48 of the drain pump 42.

Further, the working oil filled in the pressurizing chamber 45' on one side of the liquid supply pump 39 is passed through the pipe 47 to the switching valve 3.
7 and is returned to the oil tank 40.

When the liquid supply pump 39 and the liquid discharge pump 42 reach their stroke ends, the connection bracket 44 operates a limit switch (not shown), and the solenoid of the switching valve 36 is demagnetized by the control device (also not shown). Shifts to the left side and returns to the state shown, and the switching valve 37.4
1 to the right side from the state shown in the figure.

Therefore, the hydraulic pump 51 supplies the working oil from the oil tank 40 to the pressurizing chamber 45' on the other side of the supply/discharge pump 39.
The piston is normally moved to the left side and connected to the drain pump 42 via the rod 43, 43 and the connecting bracket 44.
The piston also normally moves to the left side.

Therefore, in the suction/discharge chamber 48 of the drain pump 42, as described above, the working oil is returned from the hydraulic pressure chamber 32 of the free piston pump 14, and the supply/discharge chamber 48 of the drain pump 42 is filled. The operating oil that is being used is returned to the oil tank 40 via a vibrator 49 and a switching valve 41.

Therefore, as can be seen from the above process, the working oil in the hydraulic chamber 32 of the free piston pump 14 is returned to the oil tank 40 through the supply/discharge chamber 48 of the waste liquid pump 42.
The oil is returned to the oil tank 40 in two strokes via a one-cushion pump where the oil is once returned to and stored.

On the other hand, in the pressurizing chamber 45 on one side of the liquid supply pump 39,
The pipe 46 is used to return the working oil in the hydraulic chamber 32 of the free piston pump 14 to the supply/discharge chamber 48 of the drain pump 42 and is filled with the working oil.
is fed and passes through the switching valve 36 as shown by the dotted line,
The slurry from the slurry tank 13 is fed into the hydraulic pressure chamber 32 of the free piston pump 14 from the suction pipe 34 via the flexible hose 55, and presses the free piston 30 to add the slurry from the slurry tank 13 that has been sucked into the slurry chamber 33. the slurry tank 13 by the check valve 22.
passage 25 through the drain plug 24.
It is then fed to the filter press 15.

In this process, since the pressurizing force of the working oil in the hydraulic pressure chamber 32 and the compressing force of the slurry in the slurry chamber 33 are equal, the pressure on both sides of the free piston 30 becomes the same, and no pressure difference occurs, so that the slurry and the working oil There is no mutual leakage or intermixing, and operation as designed is guaranteed.

In this way, the pistons of the liquid supply pump 39 and the liquid drainage pump 42 reach their stroke ends, and the working oil in the suction and discharge chamber 48 of the liquid drainage pump 42 returns to the oil tank 40, and the other side of the liquid supply pump 39 is pumped. When the hydraulic pressure chamber 32 of the free piston pump 14 is filled with the working oil in the pressure chamber 45, the -cycle ends, and the connection bracket 44 operates the limit switch (not shown) again to operate the control device via the control device (not shown). Hydraulic chamber 3 of free piston pump 14
2 is returned, and the operation of sucking and filling the slurry chamber 33 with slurry from the slurry tank 13 is recycled.

Then, to repeat the above process, the working oil in the pressurizing chamber 45 on one side of the liquid supply pump 39 is supplied to the hydraulic chamber 32 of the free piston pump 14, and then
In order to return the working oil in the hydraulic pressure chamber 32 of the free piston pump 14 to the oil tank 40, the working oil in the pressurizing chamber 45 of the liquid supply pump 39 is returned to the suction/discharge chamber 48 of the liquid drain pump 42. The suction filling of the hydraulic pressure chamber 32 of the free piston type pump 14 with working oil is delayed by one cycle for the oil tank 40. Therefore, when viewed from the oil tank 40, the suction filling of the hydraulic pressure chamber 32 of the free piston type pump 14 is delayed. The return of the working oil is delayed by half a cycle because it is returned after one cycle into the supply/discharge chamber 48 of the liquid supply pump 42. The filling of the working oil from 45 to the free piston pump 14 is also delayed by half a cycle, and the working oil returned to the oil tank 40 is not immediately returned to the hydraulic pressure chamber 32 of the free piston pump 14. do not have.

Therefore, the working oil is supplied to and discharged from the hydraulic pressure chamber 32 of the free piston pump 14 through the operation of the liquid supply pump 39 and the liquid drainage pump 42 without the need for providing a cooling IJI device or the like in the oil tank 40. , the free piston type pump 14 can be cooled sufficiently even without increasing the tank size for cooling.
can be operated.

Also, as shown in FIG. 2, when the free piston 30 of the free piston pump 14 moves back and forth, the seal ring 3
1, and the pressures in the hydraulic pressure chamber 32 and slurry chamber 33 are equalized, so that the slurry and working oil do not leak through the free piston 30 and mix, changing the quality of the working oil or changing its function. It will not be lowered.

Next, in the embodiment shown in FIG. 3.4, the supply and discharge pumps 38 of the above-mentioned embodiment are mechanically connected in a two-parallel manner via a connecting bracket 44, whereas the supply and discharge pumps 38 ′
is connected via the rod 43' to its liquid supply pumps 39'', 3
9' are mechanically connected in series, and the support rod 31' of the free piston pump 14' is connected to the free piston 30 of the free piston pump 14, as shown in FIG. Inserted guide rod 3
1' so that it can slide smoothly in the longitudinal direction as the free piston 30 advances and retreats, but its operation and effect are substantially the same as those of the above-mentioned embodiment.

It should be noted that the embodiments of the invention of this application are of course not limited to the above-mentioned embodiments, and various embodiments such as providing a cooling device in the oil tank can be adopted.

<Effects of the Invention> As described above, according to the invention of this application, it is possible to feed slurry using a free piston pump as a pump that is basically connected to a solid-liquid separator and pressure-feeds slurry in a slurry tank. In addition, because the hydraulic fluid is supplied to the free piston inside by the fluid supply pump, planned operation is possible, and excess high-pressure hydraulic fluid is supplied and the free piston pump is destroyed. It has excellent effects without the risk of being damaged or causing unexpected failure.

Further, the durability of the cooling device or the plant is improved, and excellent effects such as failure-free and efficient solid-liquid separation work are achieved.

Furthermore, since the hydraulic pressure chamber of the free piston pump is connected to the supply pump via the switching valve, the hydraulic fluid in the hydraulic chamber of the free piston pump can be used exclusively for supply or for discharge. , the fluid supply pump and the drainage pump are connected to the oil tank via the switching valve, so that the working oil in the hydraulic pressure chamber of the diaphragm pump is returned to the -H drainage pump and then returned to the oil tank. In addition, since the working oil supplied from the oil tank to the liquid supply pump is supplied to the hydraulic pressure chamber of the free piston type pump in one cushion, the working oil in the hydraulic pressure chamber of the free piston type pump is directly supplied to the hydraulic pressure chamber of the free piston type pump in one stroke. Therefore, the hydraulic fluid is returned to the tank and is not immediately returned to the hydraulic pressure chamber in the next stage, and vice versa. An excellent effect is achieved in that the discharged hydraulic fluid can be sufficiently cooled and circulated without requiring a cooling process by enlarging the oil tank.

Further, by such an operation, the size of the oil tank itself does not need to be increased, and there is an effect that the size of the oil tank itself can be made as compact as possible.

In addition, regarding the supply and drainage pumps, the supply and drainage pumps can be connected in series or in parallel and operated simultaneously, giving the effect of greater freedom in designing the tank size. Qin will be conquered.

By using a free piston type pump, the pressure on both sides of the free piston can be made equal, no differential pressure is generated, and the slurry does not leak through the free piston and mix with the working oil. As a result, there is an excellent effect of preventing the possibility of deterioration of the performance of the hydraulic oil or functional failure.

[Brief explanation of drawings]

Figures 1 to 4 show embodiments of the invention of this application, Figure 1 is a mechanical connection diagram of one embodiment, Figure 2 is a sectional view of the diaphragm pump of Figure 1, and Figure 3 is a separate diagram. The first example of
FIG. 4 is a sectional view of the diaphragm pump of FIG. 3, FIG. 5 is a schematic mechanical view of a conventional slurry pumping device, and FIG. 6 is a partial schematic diagram thereof. 15... Solid-liquid separator, 13... Slurry tank, 40... Oil tank, 14.14'... Slurry feeding pump (free piston type pump), 32... Hydraulic pressure chamber, 3G, 37.41...Switching valve, 38.38'...Working fluid supply and drainage pump, 12.12
'...Slurry pressure feeding device, 39.39'...Liquid supply pump, 42.42'...Drainage pump, 48...Suction and discharge chamber, 45.45'...Pressure chamber, 3
1.31'...Support net, 56...Guide, 51
...Sleeve, 30...Free piston, 31'
···rod

Claims (4)

[Claims] (1) The hydraulic pressure chamber of the slurry feed pump, which is interposed between the solid-liquid separator and the slurry tank and is connected to the oil tank, is connected to the hydraulic fluid feed and drain pump via a switching valve. In a slurry pumping device, the working fluid supply/drainage pump is composed of a fluid supply pump and a drainage pump that are mechanically linked so as to be able to operate as one unit, and the suction/discharge chamber of the drainage pump is connected to the oil tank and the fluid of the free piston pump. One pressurizing chamber of the fluid supply pump is connected to the oil tank via the switching valve, and the other pressurizing chamber is connected to the free piston via a suction/discharge passage. 1. A slurry pumping device for solid-liquid separation, characterized in that the device is connected to an oil tank and a hydraulic chamber of the free piston pump via a pump. (2) The slurry pumping device for solid-liquid separation according to claim 1, wherein the drain pump and the feed pump are connected in series. (3) The slurry pumping device for solid-liquid separation according to claim 1, wherein the drain pump and the feed pump are linked in parallel. (4) In a slurry pumping device, which is interposed between the solid-liquid separator and the slurry tank, and in which the hydraulic chamber of the slurry supply pump, which is connected to the oil tank, is connected to the supply and discharge pump via a switching valve. , the supply/drainage pump is composed of a fluid supply pump and a drainage pump that are mechanically linked so as to be able to operate as one unit, and a suction/discharge chamber of the drainage pump is communicated with an oil tank and a hydraulic pressure chamber of a free piston type pump. One pressurizing chamber of the fluid supply pump is connected to the oil tank via the switching valve, and the other pressurizing chamber is connected to the oil tank via the free piston pump. The free piston pump is connected to the tank and the hydraulic chamber of the diaphragm pump, and the free piston of the free piston pump is fixed to a rod inserted through the front and rear lids of the casing while sealing. A slurry pumping device for solid-liquid separation.