Patent Application
20240200542
This application claims priority to German Patent Application No. DE 10 2021 002 178.9, filed on Apr. 24, 2021 with the German Patent and Trademark Office. The contents of the aforesaid Patent Application are incorporated herein for all purposes.
The invention relates to a conveying device for fluids with an inlet and an outlet and a conveying part which is connected therebetween and can be actuated by a drive part.
This background section is provided for the purpose of generally describing the context of the disclosure. Work of the presently named inventor(s), to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
WO 2013/079222 A2 discloses a conveying device for improving the energy efficiency in hydraulic systems, having an actuator which in one operating state operates as a consumer of hydraulic energy and in another operating state operates as a producer of hydraulic energy, and having a hydraulic accumulator which in the one operating state of the actuator can be charged by said actuator for energy storage and in the other operating state can be discharged for delivering energy to the actuator. A discontinuous, adjustable hydropneumatic piston accumulator, in which a plurality of pressure chambers are formed that are adjacent to differently sized effective areas on the fluid side of the accumulator piston, serves as the hydraulic accumulator. In addition, an actuating arrangement is provided which, depending on the respective pressure levels prevailing on the gas side of the piston accumulator and at the actuator, connects a selected pressure chamber or a plurality of selected pressure chambers of the piston accumulator to the actuator.
This results in the possibility of recycling energy independently of the precharge pressure on the gas side of the accumulator and independently of the respective load pressure because, by selecting an effective area of suitable size, the respective desired pressure level at the accumulator can be used for charging or discharging. This enables optimum energy conversion in all operating states. The known multi-piston arrangement for the piston accumulator requires seals, such as metallic piston rings or rubbery-elastic plastic seals, to seal the individual piston chambers against each other. Due to the high forces and pressures which occur during operation, it is usually also necessary to additionally use lubricants to keep the friction forces as low as possible so as thus to reduce wear and create a seal that is as leak-free as possible. Nevertheless, leaks cannot be avoided and friction causes wear on both the individual pistons and the associated sealing material. Although these wear particles are usually small, they nevertheless lead to contamination of the gases or liquids to be conveyed, some of which can also be of high purity, which can then in turn only be remedied by very elaborate filtering measures in the fluid flow.
Based upon this prior art, a need exists to provide a conveying device with which it is possible to prevent contamination from entering the fluid to be conveyed or compressed. The need is addressed by the subject matter of the independent claim(s).
Embodiments of the invention are described in the dependent claims, the following description, and the drawings.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description, drawings, and from the claims.
In the following description of embodiments of the invention, specific details are described in order to provide a thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the instant description.
In some embodiments, the conveying part has a fluid-tight media-separating device with a variable chamber volume, which becomes connected in a fluid-conducting manner via its receiving chamber to the inlet or the outlet, and which, by means of the drive part, receives fluid via the inlet as part of an intake stroke, increasing the chamber volume, and discharges the received fluid via the outlet as part of a discharge stroke, reducing the size of said chamber volume thus ensuring that no leaks occur in the conveying part and also that no contamination enters the fluid to be conveyed or compressed. The fluid-tight media-separating device ensures that no medium from the drive side can reach the conveying side for the fluid and in this respect also prevents any contamination from entering on the transport fluid side. The conveying device can transport incompressible fluids, such as any type of liquids; but also compressible media, for example in the form of high-purity gases, such as hydrogen, which are compressed in the process. It is also possible to convey or compress fluids composed of compressible and incompressible fractions. In this respect, undesirable entry of a working gas on the liquid side is similarly prevented.
In some embodiments of the conveying, it is provided that the media-separating device is formed of a bellows which is fluidically controlled from the outside by means of the drive part in such a manner that the inner chamber volume of the bellows increases during an intake stroke and decreases during a discharge stroke. In practice, the bellows used as a media-separating device, usually in the form of conventional bellows, is regarded as absolutely media-tight, i.e., no medium can pass through the bellows wall either from inside to outside or vice versa, and with an appropriate configuration in stainless steel, the media-separating device is also to be regarded as resistant to embrittlement in hydrogen applications. Due to the pleated configuration of the bellows, it has only a relatively small storage and discharge volume in volumetric terms compared with other hydraulic accumulators, such as bladder accumulators for example; compared with the elastomeric accumulator bladder alone, conveying operation can be achieved with high cycle times, during which the individual bellows pleats go into full contact with each other in the contracted state of the bellows, which stabilises the bellows arrangement as a whole and helps to prevent malfunctions.
In some embodiments of the conveying device, it is provided that the drive part has a hydraulic working cylinder which can be controlled by means of a hydraulic drive and a main valve. In this way, actuation of the conveying part, which can also act as a compressor part, can be controlled using conventional hydraulic components for the drive part. The said components of the drive part can be standardised and thus easily adapted to the desired conveying and compression output for the conveying part or compressor part.
In some embodiments of the conveying device, it is provided that the hydraulic working cylinder with its piston-rod unit uses a metering chamber of predefinable metering volume to predefine the intake and discharge stroke for the conveying part, for example on the piston side and that for example the working cylinder is actuated via the main valve on the rod side. The metering volume referred to is almost incompressible with the result that a movement of the hydraulic working cylinder as a so-called pump cylinder can be transferred to the media-separating device without loss or delay. Particularly for smaller volume flows and lower pressures, the function can also be swapped from piston side to rod side. In this way, it is possible to transmit pressure in both directions.
In some embodiments of the conveying device, it is provided that, in order to obtain a homogenised conveying volume flow, a further conveying part is provided which performs a discharge stroke, while the other conveying part performs an intake stroke and vice versa. In this way, the conveying device can be operated virtually continuously, with one conveying part always ensuring the discharge of fluid under pressure, while the further conveying part is loaded with fluid in the intake stroke for the subsequent discharge stroke.
In this case, it is beneficial that the further conveying part is likewise connected to the working cylinder which has a second piston that is connected to the piston rod by way of the first piston for the one metering chamber, thus forming a further metering chamber of predefinable metering volume. In this way, the conveying device can be operated with two conveying parts in synchronous sequence with only one working cylinder or pump cylinder.
In some embodiments of the conveying device, it is provided that for conveying gases the respective conveying part acts as a compressor part, that two compressor parts form a single-stage compressor and that the interconnection of a plurality of single-stage compressors results in a multi-stage compressor. In this way, a low pressure existing on the gas inlet side can then be brought to a higher medium pressure in comparison by means of the first compressor stage which medium pressure is converted in turn into high pressure by means of the second compressor stage on the gas outlet side.
In some embodiments of the conveying device, it is provided that, particularly to compensate for leaks at the working cylinder, at least one metering unit is present which h introduces small quantities of metering volume into the respective metering chamber or discharges them therefrom.
The metering unit can be used for example to add small volumes to the metering volume of the working or pump cylinder or if necessary to withdraw them from this metering volume. For this purpose, the respective metering unit is for example connected to a metered adding or withdrawal unit by means of metering valves and the respective metering unit can be protected by a secondary pressure protection device. The metering valves can be used to perform very precise metering processes and the secondary pressure protection device mentioned, which may for example consist of a pressure relief valve, serves to protect against overloads.
Furthermore, it may for example be provided that the positions of the working cylinder can be detected via an end position monitor. In this way, it is possible to monitor the function for the working or pump cylinder, in which case a different form of a cylinder monitor can be used instead of an end position monitoring.
In some embodiments of the conveying device, it is provided that homogenisation of the conveying flow takes place by means of hydraulic accumulators, in particular in the form of medium and high-pressure gas accumulators. Thus, even with only one conveying part with intermittent delivery stroke, it is basically possible to achieve a homogenised conveying volume flow even within the scope of conveying gas.
In some embodiments of the conveying device, it is provided that at least one cooling device is inserted between individual compressor stages. It has been shown that, particularly when using multi-stage compression for conveying and compressing gases, such as hydrogen, the temperature can rise significantly, leading to undesirable expansion of the gas, which in turn would lead to an increase in the drive power needed in this respect for the individual conveying or compressor parts, which can be prevented by the aforementioned intermediate cooling between the compressor stages.
In some embodiments of the conveying device, it is provided that the fluid flow, in particular gas flow, on the discharge side of each compressor part is monitored by means of contamination sensors. If contamination is detected, even if unlikely, the relevant plant section of the conveying device should be shut down immediately so that any parts which are contaminated or have become unusable can be replaced as part of maintenance.
Particularly when conveying or transporting high-purity gases, such as hydrogen, there must be no particulate contamination in the gas flow within the scope of the intended use, for example in fuel cell operation.
Due to its modular design, the compressor solution according to the present teachings not only facilitates adaptation to required compressor mass flows by appropriate scaling of the media-separating devices according to size and number, but also allows easy adaptation of the compression ratios themselves. In addition, in the area of control, the associated hydraulic control circuit with its components is only single and not executed multiple times for a plurality of conveying and compressor parts. Accordingly, a specific use of the conveying device provides for compression of hydrogen gas in stages using individual, identical compressor parts. This thus has no equivalent in prior art.
The discussed conveying device is explained in greater detail in the following with reference to further embodiments according to the drawings. The drawings show principles and are not to scale.
Specific references to components, process steps, and other elements are not intended to be limiting. Further, it is understood that like parts bear the same or similar reference numerals when referring to alternate FIGS.
The conveying part denoted as a whole by 10 in
The stroke volume of the media-separating device 16 or the bellows, respectively, is designed in such a manner that it is greater than the displacement of the metering volume that can be generated by a maximum pump cylinder movement of a drive part 18 (
The media-separating device 16 shown in
On the one hand, separation of the two fluids of the system from each other, namely the hydraulic fluid used in the metering volume from the high-purity gas to be conveyed and if necessary compressed, and, on the other hand, the actual conveying and compressor function.
For separating the fluid systems, the media-separating device 16, in the form of the bellows, permits hermetic separation and, for the conveying and compressor function, the bellows possesses highly flexible deformability with a large stroke volume. In addition, during a compression process, very high gas temperatures occur in the gas chamber, i.e., in the inner or receiving chamber 21 of the bellows, depending on the desired compression ratio, which said chamber has to withstand without damage. The requirements to this effect can be met with an appropriately designed metal bellows.
For the conveying and compressor function, the media-separating device 16 is equipped with valves, in the form of two non-return valves 22 acting in opposite directions, as so-called compressor valves. So that the media-separating device 16, in the form of the bellows, can be removed easily and without major gas losses in the event of servicing, it has a switchable directional-control valve 24 on the inlet 12 side in the associated fluid duct which, in the blocked state, according to the diagram shown in
Proper function of the media-separating device 16 is constantly monitored, in particular by the two signal transmitters 20 of the end position monitor which signal that the associated end positions have been reached during the stroke of the metal bellows. If the metal bellows assumes its maximum extended position at maximum chamber volume, it actuates the lower end position monitor 20, viewed in the direction of
Furthermore, a contamination sensor 30 is located on the outlet side of the conveying part 10, such as shown by way of example in
The upper end of the bellows is connected to a separating plate 32 which divides a housing 34 of the conveying part 10 into two chambers separated from each other, the contamination sensor 32 being arranged in the upper chamber as well as a pick-up point for the discharge device 28 on the inlet side of the conveying part. The second lower chamber accommodates the bellows which is hermetically sealed on its underside with a bellows plate 36, and between the outside of the bellows and the inside of the relevant housing part an intermediate or fluid chamber 38 is formed which is in communication with the drive part 18 via a fluid-conducting connection 40 and forms the connection for the driving metering volume of the drive part 18 for operating the conveying or compressor part 10.
The possible directions of fluid flow are shown by arrows in FIG. 1. Thus, when the bellows is extended by means of the drive part 18 and the directional-control valve 24 is switched to its fluid-transmissible position, fluid to be conveyed flows into the receiving chamber 21 of the bellows via the inlet 12 and the right-hand compressor valve 22, viewed in the direction of
Of course, a conveying pause occurs during operation of the conveying or compressor part 10 according to
The drive part 18 has a hydraulic working or pump cylinder 46 which can be controlled by means of a hydraulic drive 48 and a main valve 50. Furthermore,
In the case of smaller conveying and compressor parts 10, the main valve 50 can also be single-stage because then only smaller volume flows, for example <100 l/min, are required. However, in the case of multi-stage compressors as shown in
Between the working or pump cylinder 46 and the respective media-separating device 16, which are connected to each other via the respective connection 40, there is a volume of liquid, which is referred to as the metering volume 54, 56, and which is pushed back and forth between the cylinder 46 and the respective media-separating device 16. This metering volume 54, 56 is almost incompressible with the result that a movement of the cylinder 46 can be transferred to the respective media-separating device 16 without loss or delay. In this case, the respective metering volume 54, 56 is bounded by a piston face of the piston-rod unit 60, the rod side being connected to the outlet of the main valve 50 by fluid lines. In this respect, the rod of the piston-rod unit 60 divides the cylinder 46 into two rod-side fluid chambers 64 and 66.
The metering unit 52, which can add small volumes into the respective metering volume 54, 56 or can withdraw small volumes from said metering volume, is used to compensate for leaks at the working or pump cylinder 46. The metering unit 52 consists in this respect of two small, self-contained reciprocating pistons which, for moving from one end position to the other, can take up a small, defined stroke volume (for example of <10 cm3) and discharge it on the other which is initiated by switching associated directional-control valves 68, 70 for metering in or metering off. The metering in unit with reciprocating piston and associated directional-control valve is denoted by 72 in
As
With the solution shown in
In the multi-stage, in particular two-stage, compressor design according to
The basic configuration of a two-stage compressor according to
Embodiments of such a contamination sensor 30 are shown in greater detail in
Such contamination sensors 30 can be constructed according to various principles, at least two functions are to be fulfilled in the present case:
On detecting contamination, it should be possible to shut down the associated plant section immediately in order to eliminate the cause of the contamination and to replace contaminated parts, for which it is only necessary to interrupt plant operation for a short time. With the technical solution of a contamination sensor 30 according to
The contamination sensor 30 according to
A signal is emitted if a corresponding increase in flow resistance is detected in the presence of contamination. The differential pressure measurement using the pressure measuring device 106 is carried out with circuit output and the filter fleece 98 can be an impregnatable filter mat which, when impregnated with oil, produces a higher flow resistance than the clean filter fleece 98 according to
With both sensor principles, the filter fleece 98 that triggered the signal due to contamination can be replaced so that the respective sensor 30 can continue to be used if necessary.
With higher compression ratios, for example 24, the multi-stage compressors according to the embodiments shown in
The conveying device is particularly suitable for hydrogen applications; however, it can also be used to transport and convey other fluids, including those that are completely incompressible and therefore not compressed during conveying.
The invention has been described in the preceding using various exemplary embodiments. Other variations to the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor, module or other unit or device may fulfil the functions of several items recited in the claims.
The term “exemplary” used throughout the specification means “serving as an example, instance, or exemplification” and does not mean “preferred” or “having advantages” over other embodiments. The term “in particular” and “particularly” used throughout the specification means “for example” or “for instance”.
The mere fact that certain measures are recited in mutually different dependent claims or embodiments does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 002 178.9 | Apr 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/059908 | 4/13/2022 | WO |
