EP1898093A1 - Pumping device - Google Patents

Abstract

The device (1) has a diaphragm pump head (2) with a fluid delivery chamber (4) and a diaphragm (3), which are hydraulically coupled to another head (8) for driving the former head. The later head has a fluid delivery chamber (10) and a diaphragm (9) which are drivable by a double-acting piston via diaphragm control chambers (5, 11). Refilling valves (38, 40) are connected to the control chambers that are impinged temporarily using the valves, during a refilling procedure, and are controlled by a diaphragm position by diaphragm control pressure, which is greater than atmospheric pressure.

Description

The invention relates to a pump device with a first diaphragm pump head and a second diaphragm pump head hydraulically coupled thereto.

For the promotion or recirculation of viscous media with high solids content (suspensions) at high pressures of over 200 bar and high temperature of over 300 ° C piston pumps can be used. However, they are suitable for such an application only limited, since the solids fractions in a relatively short time destroy associated seals a piston and cause scoring on a surface of the piston.

One way around these difficulties is to use diaphragm pumps. In order to realize a conveying at the above-mentioned pressures, only constructions can be used with hydraulically driven membranes. These in turn can be designed only under considerable constructive and material technical effort for a safe and trouble-free operation in the temperature range mentioned.

The use of plastic membranes, for example made of PTFE, is not possible because plastic begins to flow to a considerable degree at the high pressure and high temperature mentioned. The use of metal membranes is possible in principle, but technical requirements such as multi-layer membrane with fracture signaling and a design as a freely oscillating in the product space membrane with layer control can be realized only with great effort, see EP 0 085 725 A1 ,

As a measure against the high temperature load so far pumps with a so-called remote valve head have been used. In such a construction works one Diaphragm pump as an upstream pulsator, which operates via a pipeline serving as a cooling line, the working valves in the downstream remote valve head of the pump by means of the fluid to be delivered. This ensures that the diaphragm pump can operate in the uncritical low-temperature range up to approx. 150 ° C. The disadvantage, however, is that possible solids content of the fluid to be pumped can clog the pipe between the upstream pulsator and the remote valve head and thus the conveying effect is impaired.

The high pressure of the fluid to be pumped leads to another problem. The piston rod force of reciprocating displacement pumps resulting from the product of pressure and area may require the use of very large pump drive assemblies which may be uneconomical for the required application in two respects. On the one hand, this entails considerably higher investment costs and, on the other hand, higher life-cycle costs, which can be characterized in particular by energy costs and expenditures for wear and spare parts. The economic consideration of pump systems for recirculation with the boundary conditions mentioned above is of particular importance in processes for energy recovery from biological waste.

It is therefore an object of the invention to provide a pump device which can promote viscous media with high solids content at high pressures of over 200 bar and high temperatures of over 300 ° C reliably and inexpensively.

The object is solved by the features of independent claim 1. Advantageous embodiments of the invention are described in the subclaims.

The pump device according to the invention comprises a first diaphragm pump head with two or an integer multiple of two fluid delivery chambers and associated membranes, which are hydraulically coupled to a second diaphragm pump head, wherein the second diaphragm pump head has two additional fluid delivery chambers and associated additional membranes that of a double-acting piston can be driven via associated diaphragm control chambers, wherein in each case a refill valve is connected to the diaphragm control chambers and the membrane control chambers are temporarily acted upon by the Nachfüllventile with a membrane pressure which is greater than atmospheric pressure.

Such a pumping device is advantageous in that, at a time when the refill valves top up the diaphragm control chambers with a control fluid to compensate for unavoidable leakage of the control fluid, a short-term pressure drop in the diaphragm control chambers, which has hitherto been common in position-controlled diaphragms, up to atmospheric pressure through the diaphragm control chambers superimposed diaphragm control pressure which is greater than the atmospheric pressure can be limited.

By using the pump device according to the invention it is achieved that a movement of the piston is possible at any time with a lower force than in solutions in the prior art, so that a delivery pressure are passed alternately into the respective diaphragm control chambers of the second diaphragm pump head and from there to the first diaphragm pump head can to transport fluid through the first diaphragm pump head. Although the total pressure in the first diaphragm pump head for conveying the fluid may be relatively high, it is possible to pump with a relatively small force exerted on the piston and thus generated pressure difference. This creates a situation as if the piston would exert the pressure increase directly in the first diaphragm pump head. By the pump device according to the invention, it is possible that the piston can be driven by a drive unit, which can be designed for much lower forces than in previously known solutions, so that a much cheaper conveying at high temperatures and pressures in the first diaphragm pump head is achieved.

Preferably, the pump device is configured such that the diaphragm control pressure corresponds approximately to a fluid pressure at the inlet of a fluid delivery chamber of the first diaphragm pump head. This allows almost complete compensation of the described short-term pressure drop in the diaphragm control chamber of the second diaphragm pump head. In combination with a double-acting design of the piston of the second diaphragm pump head, this has the consequence that the drive unit for the piston only has to be designed for forces which correspond approximately to the pressure difference between the inlet and the outlet of a fluid delivery chamber of the first diaphragm pump head.

In the case of the pump device according to the invention, the membrane control pressure can preferably be adapted to the fluid pressure by means of a control loop with associated sensors and actuators. Especially with an electronic control circuit this allows an optimally coordinated Compensation of the described pressure drop and thus the prevention of pressure surges, which can exert a detrimental effect on the drive unit.

The membrane control pressure may be generated by a pump which is coupled to a respective container for a diaphragm control chamber, each container having one of the refill valves and each container is acted upon by the pump with a static back pressure. In such an embodiment, the pump is permanently in operation.

According to an alternative embodiment, the membrane control pressure can be generated by a controllable pump which feeds a pressure accumulator, which is in each case coupled to a container for a diaphragm control chamber. The container serves as a refill reservoir in this case. In this embodiment, it is possible that the pump is only in operation when a predetermined lower limit pressure in the accumulator is exceeded. The pump then operates until an upper limit pressure is reached again in the accumulator (two-step control).

Further, it is possible to provide a respective container as a refill reservoir of a control fluid for a diaphragm control chamber of the second diaphragm pump head, wherein each container an adjustable throttle device is connected downstream. In this case, the pump can be constantly in operation, so that a continuous circulation of a control fluid is given.

The structure of the pumping device and its operation is relatively symmetrical when the piston is designed as a double-acting disc piston with opposing piston rods. In this case, the piston surfaces on both sides of the disc piston have an identical size, so that during a suction stroke or pressure stroke in each case the same pressure change and the same volume displacement is generated.

If the membranes of the first diaphragm pump head are each free-swinging metal membranes, due to the material metal, a fluid can be transported at high temperatures. Since the first diaphragm pump head and the second diaphragm pump head are coupled via lines with a control fluid, these lines can act as cooling sections. Thus, in a preferred embodiment, the membranes of the second diaphragm pump head may be formed of a plastic, in particular PTFE, so that none There is a risk that these plastic membranes show a significant flow because of too high a temperature.

If the membranes of the second diaphragm pump head each have a multi-layered design and are provided with a position control and breakage signaling, the safety during conveying of the fluid can be increased. An even higher level of safety is achieved if a conductivity or viscosity sensor is provided within the diaphragm control chambers of the first diaphragm pump head. Should a metal diaphragm break in the first diaphragm pump head, the fluid to be delivered could enter the adjacent diaphragm control chambers, so that a mixing of delivery fluid and control fluid would occur. Such mixing may alter the electrical conductivity or viscosity of the mixture as compared to the values of the control fluid so that the sensor can detect a break in a metal membrane.

The hydraulic coupling between the first diaphragm pump head and the second diaphragm pump head may be by means of control fluids comprising water or oil. As the oil, for example, a special heat transfer oil can be used when the pumping device is used to convey a fluid at high temperatures.

Fig. 1

eine schematische Darstellung einer Ausführungsform der erfindungsgemäßen Pumpenvorrichtung.

The invention will be further described with reference to an embodiment shown in the drawing. It shows:

Fig. 1

a schematic representation of an embodiment of the pump device according to the invention.

In Fig. 1, a pump device 1 with a first diaphragm pump head 2 and a second diaphragm pump head 8 is shown. The first diaphragm pump head 2 has a first diaphragm 3, which separates a first fluid conveying chamber 4 from a first diaphragm control chamber 5. A fluid to be conveyed through the first fluid conveying space 4 is supplied to an inlet port 6 with a suction valve 61 through a supply line 60 in which a fluid pressure p1 prevails (see arrow 7). The fluid can be transported at a bulge of the first membrane 3 through the first fluid conveying space 4 to a pressure valve 62 at one end of the fluid conveying space 4. The bulging of the membrane 3 is effected by the application of a pressure in the first diaphragm control chamber 5. If there is applied by dp higher pressure, there is a pressure p1 + dp at the pressure valve 62, with which the fluid is transported to the discharge line 63.

The pressure p1 + dp is provided by a first conduit 13 from a second diaphragm pump head 8. This has a second membrane 9, which separates a second fluid delivery chamber 10 from a second diaphragm control chamber 11. The second fluid delivery chamber 10 is coupled to the first diaphragm control chamber 5 by a first control fluid 12. In a bulging of the second diaphragm 9, this first control fluid 12 is passed through the first line 13 to the first diaphragm control chamber 5, so that the first diaphragm 3 bulges. Such a displacement of the first control fluid 12 is achieved by means of a piston 15, which exerts a stroke, which is directed downward in the embodiment shown in Fig. 1. A second control fluid 14 present in the second diaphragm control chamber 11 serves as the transmission medium for the volume change in an associated lower piston chamber 32. The second diaphragm control chamber 11 extends as far as a disk piston 31 of the piston 15, so that the lower piston chamber 32 forms part of the second diaphragm control chamber 11.

The stroke movement of the disk piston 31 in a direction pointing downwards in the embodiment shown in FIG. 1 is effected by a pump drive unit 51 by means of a first piston rod 33. On the disk piston 31, a second piston rod 35 is arranged opposite to the first piston rod 33. Thus, the disk piston 31 is constructed symmetrically, so that on both opposite end faces of the disk piston 31, the same area is present. This has the consequence that in a piston stroke in the lower piston chamber 32, the same amount of pressure and volume change is achieved as in a piston stroke in an opposite upper piston chamber 34th

The upper piston chamber 34 is part of a third diaphragm control chamber 17 which is separated from a third fluid delivery chamber 19 by a third diaphragm 18. In a downward stroke movement of the disk piston 31, the volume of the upper piston chamber 34 increases, so that the third diaphragm 18 is contracted or compressed. The transfer medium used is a third control fluid 16 in the third diaphragm control chamber 17.

Transport of a fluid which has been conducted into the first fluid conveying space 4 with a pressure p1 is achieved when a pressure p1 + dp is transferred into the first diaphragm control chamber 5 via the line 13. Thus, this pressure p1 + dp must prevail in the second fluid delivery chamber 10. This is only possible if such a pressure is built up in the second diaphragm control chamber 11. In solutions according to the prior art, it is common for a drive unit apply this entire pressure p1 + dp to one or two single acting plungers. In the embodiment according to the invention, however, this is no longer necessary. 1, the pressure p1 alternately across the membranes 3 and 24, the control fluids 12 and 21, the membranes 9 and 18 and the control fluids 14 and 16 respectively on the piston chamber 32 and 34 executing the suction stroke transfer. When the unavoidable leakage of the control fluids 14 and 16 through the refill valves 38 and 40, which are actuated by the diaphragm position control, is compensated, a short-term pressure drop to atmospheric pressure takes place in the respective diaphragm control chamber. In the pump device according to the invention, a pressure p2 is then superimposed on the pressure present in the diaphragm control chambers 11 and 17, so that the pressure reduction can be compensated.

If the piston of the second diaphragm pump head is designed as a double-acting piston and the pressure p2 is approximately equal to p1, only such a force must be exerted on the piston rod 33 with the pump drive unit 51 that the piston 15 only generates a differential pressure dp. If, for example, p1 = 250 bar, a transport of the fluid through the first fluid conveying space 4 can be achieved with a differential pressure of dp = 20 bar. The pump drive unit 51 therefore no longer has to be designed for p1 + dp = 270 bar, but only for 20 bar. This allows a much more economical fluid transport.

The pressure p2 is provided by a pump 50 via a supply line 36 to the containers 37 and 39. In the case of the refilling process controlled by the membrane position, the pressure p2 is forwarded into the membrane control chambers 11 and 17. Excess control fluid is discharged via a vent valve 42 and 44 into a container 41 and 43, respectively, and conducted by means of a return line 53 into a control fluid reservoir 52.

During a downward stroke of the disc piston 31, the upper piston space 34 is increased, so that the third diaphragm 18 is compressed. This also increases the volume of the third fluid delivery chamber 19, which is coupled via a fourth control fluid 21 and the second conduit 22 to a fourth diaphragm control chamber 23. The fourth diaphragm control chamber 23 is located in the embodiment shown in FIG. 1 in the first diaphragm control head 2 and is separated by a fourth diaphragm 24 from a fourth fluid conveying chamber 25. This structure is a mirror image of the structure with the first membrane 3, the first fluid conveying chamber 4 and the first diaphragm control chamber 5. At an enlargement of the third fluid conveying space 19, the volume of the fourth fluid delivery chamber 25 is increased, so that a suction or a fluid supply via the inlet opening 26 takes place with the suction valve 64. If the disc piston is moved in an upward stroke, the conditions described above are reversed. Then, the fourth fluid delivery chamber 25 conveys a fluid through an outlet port 28 by means of a vent valve 65 into a discharge line 63, while the first fluid delivery chamber 4 is filled.

The first membrane 3 and fourth membrane 24 are free-swinging metal membranes. On a multi-layer design and a membrane layer control can be omitted. A check as to whether a breakage of a metal membrane has occurred can be made indirectly by means of a conductivity or viscosity sensor 29 or 30. At a break of e.g. the membrane 3, there is a mixing of the fluids in the first fluid conveying space 4 and the first diaphragm control chamber 5, so that the electrical conductance or the viscosity changes, which can be detected by the sensors 29 or 30.

If, for example, the third diaphragm 18 is compressed in the pump device in the second diaphragm pump head 8 during a suction stroke of the disc piston 31 in such a way that it reaches its rear end, the pressure in the third diaphragm control chamber 17 can drop to below or below the atmospheric pressure, as mentioned above , This is undesirable, since in this case a significant increase in the thrust force of the piston 15 occurs abruptly and the pump drive unit is heavily loaded. In the case of the pump device according to the invention, this can be avoided by the permanent pressurization with p2, which corresponds approximately to p1, via the containers 37 and 39.

In a further advantageous embodiment (not shown in FIG. 1), the second diaphragm pump head 8 for the respective second 9 and third diaphragm 18 has a separate diaphragm position control, as described in US Pat EP 0 085 725 A1 is disclosed. The respective refill valves 38 and 40 are replaced by a spring-mounted control plunger, which has a region with a conical surface screwed into its circumferential surface, and a tumbling rod operatively connected therewith, which in turn releases or blocks a spring-loaded refill valve. In the region of the respective diaphragm control chamber 17 or 11, a spring-mounted support plate secured against falling out in the direction of the respective diaphragm 18 or 9 and provided with passage openings for the respective control fluid 16 or 14 is arranged, which is in operative connection with the control tappet. Has a loss give the control fluid 16 and 14, so shifts the respective towards the diaphragm control chamber 17 and 11 directed end position of the diaphragm 18 and 9, so that the support plate against the spring force supporting them and against the plunger supporting spring force is moved. The movement of the support plate thus moves the control plunger, so that its conical peripheral region releases the tumbler, which, for example, falls by gravity in the direction of the control plunger longitudinal axis. Alternatively, for example, a spring force the tumbler in the direction of the control plunger. As a result, the refill valve is released by the tumbler, so that due to the pressure prevailing in the diaphragm control chamber 17 and 11 negative pressure, the refill is opened against the supporting spring force and the control fluid 16 and 14 can flow into the respective diaphragm control chamber 17 and 11 respectively. Once again the normal control pressure has built up in the diaphragm control chamber 17 and 11, the previously shifted end position of the affected membrane moves back 18 or 9 in the correct end position and thus again releases the support plate which releases the control plunger and thus the tumbler bar pushes back into the blocking position, whereby the valve is locked, which is also closed by the pressure balance due to its supporting spring again.

Moreover, in another embodiment of the invention, it is possible to arrange the double-acting piston 15 outside the second diaphragm pump head 8. In this case, the piston 15 is arranged with the disc piston 31 and the piston rods 33 and 35 in a separate from the diaphragm pump head 8 control fluid-tight housing, which includes the piston 15 receiving piston chambers 32 and 34 and flexible or installed lines for the control fluid 16 and 14. These lines connect the respective piston chambers 32 and 34 with the diaphragm control chambers 16 and 11th

Claims (12)

Pump device (1), comprising: a first diaphragm pump head (2) with two or an integral multiple of two fluid delivery chambers (4, 25) and associated diaphragms (3, 24) hydraulically coupled to a second pump head (8) for driving the first diaphragm pump head (2), characterized in that
the second pump head (8) is a diaphragm pump head (8) which has two additional fluid feed chambers (10, 19) and two associated additional diaphragms (9, 18), which are provided by a double-acting piston (15) arranged in the second diaphragm pump head (8). via associated diaphragm control chambers (11, 17) are drivable,
wherein in each case a refill valve (38, 40) is connected to the membrane control chambers (11, 17), and by means of the refill valves (38, 40), the membrane control chambers (11, 17) temporarily, during the diaphragm-controlled refilling, with a membrane control pressure (p2) acted upon which is greater than atmospheric pressure and less than the system pressure (p1 + dp). Pumping device (1) according to claim 1,
characterized in that
the diaphragm control pressure (p2) corresponds approximately to a fluid pressure (p1) at the inlet (6, 26) of a fluid delivery chamber (4, 25) of the first diaphragm pump head (2). Pump device (1) according to claim 1 or 2,
characterized in that
the diaphragm control pressure (p2) can be adapted to the fluid pressure (p1) by means of a control loop with associated sensors and actuators. Pump device (1) according to one of claims 1 to 3,
characterized in that
the membrane control pressure (p2) is generated by a pump (50), which is in each case coupled to a reservoir (37, 39) for a diaphragm control chamber (11, 17), each reservoir (37, 39) of one of the refill valves (38, 40 ) and is acted upon by the pump (50) with a static back pressure. Pump device (1) according to one of claims 1 to 3,
characterized in that
the diaphragm control pressure (p2) is generated by a controllable pump (50) which feeds a pressure accumulator which is in each case coupled to a reservoir (37, 39) for a diaphragm control chamber (11, 17). Pump device (1) according to one of claims 1 to 3,
characterized in that
a respective container (37, 39) for a diaphragm control chamber (11, 17) is provided and each container (37, 39) is followed by an adjustable throttle device. Pumping device (1) according to one of claims 1 to 6,
characterized in that
the piston (15) is designed as a double-acting disk piston (31) with opposite piston rods (33, 35) of the same cross-sectional area. Pump device (1) according to one of claims 1 to 7,
characterized in that
the membranes (3, 24) of the first diaphragm pump head (2) are each free-swinging metal membranes (3, 24). Pumping device (1) according to one of claims 1 to 8,
characterized in that
the membranes (9, 18) of the second diaphragm pump head (8) are formed from a plastic, in particular PTFE. Pumping device (1) according to one of claims 1 to 9,
characterized in that
the membranes (9, 18) of the second diaphragm pump head are each formed in multiple layers and provided with a position control and breakage signaling. Pump device (1) according to one of claims 1 to 10,
characterized in that
within membrane control chambers (5, 23) of the first diaphragm pump head (2) a conductivity or viscosity sensor (29, 30) is provided. Pump device (1) according to one of claims 1 to 11,
characterized in that
the hydraulic coupling between the first diaphragm pump head (2) and the second diaphragm pump head (8) is effected by means of control fluids (12, 21) which comprise water or oil.

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