Reciprocating pump

Abstract

The invention relates to a reciprocating pump (100) comprising a liquid supply chamber (110) having an inlet port (111) and an outlet port (112), which liquid supply chamber is configured such that a liquid to be pressurized is arranged in the supply chamber; a pumping chamber (130) arranged within the liquid supply chamber (110) and in fluid communication with the fluid supply chamber (110); a piston (120) configured to be reciprocated in the pumping chamber (110) along a motion axis (121) such that by means of the reciprocation of the piston (120) the liquid is transported from the fluid supply chamber (110) into the pumping chamber (130) and pressurized therein, wherein the piston (120) at least partially protrudes from outside the fluid supply chamber (110) into the fluid supply chamber (110); wherein within the fluid supply chamber (110) at a predetermined position (171) at which the piston (120) protrudes from outside the fluid supply chamber (110) into the fluid supply chamber (171) a heat shield unit (170) is arranged, wherein the heat shield unit (170) is configured to at least partially absorb heat (175) conducted from outside the fluid supply chamber (110) into the fluid supply chamber (110) and / or into the pumping chamber (130) and to transfer the absorbed heat to the outlet port (112).

Description

[0001] This invention relates to cryogenic reciprocating pumps. Background Technology

[0002] Cryogenic reciprocating pumps can be used to increase the pressure of liquids at extremely low temperatures (e.g., below -100°C). For this purpose, the pump may include a piston that reciprocates within a cylinder or sleeve, thereby defining a pumping chamber. This pumping chamber may be in fluid communication with a supply chamber, into which the liquid to be compressed may be supplied, for example, by gravity, hydrostatic pressure, or by means of another pump. By means of the reciprocating motion of the piston, liquid can be conveyed from the supply chamber to the pumping chamber, pressurized in the pumping chamber, and discharged via a discharge outlet. For the pump to operate effectively, it may be important that the liquid conveyed from the supply chamber to the pumping chamber is as cold as possible. An example of a pump that avoids heat intake is described in KR20230077793A1, which shows a pump mounted vertically. Summary of the Invention

[0003] This invention relates to a cryogenic reciprocating pump having the features of claim 1. Embodiments and advantages form the subject matter of the dependent claims and the subject matter of the following description.

[0004] The pump includes a liquid supply chamber, suction chamber, or receiving chamber configured such that the liquid to be pressurized (e.g., a cryogenic liquid) is disposed in the supply chamber. The liquid supply chamber includes an inlet or inlet port through which the liquid to be pressurized is introduced, for example by gravity or by another pump. The liquid supply chamber also includes an outlet or outlet port through which heated or vaporized liquid is discharged from the supply chamber. For example, the liquid supply chamber may be connected to a storage tank such that liquid from the storage tank is delivered to the liquid supply chamber through a chamber inlet (e.g., via a suction line), and that heated or vaporized liquid is returned from the supply chamber to the storage tank through the outlet port. The outlet port may advantageously be configured to remove heated or vaporized liquid from the supply chamber so that the coldest liquid is available for the pumping chamber. Separation between the cold fluid and the hot / vaporized fluid may be achieved by gravity and / or convection (because the cold fluid is heavier than the hot fluid). Therefore, the inlet port can be advantageously located at the bottom of the supply chamber, and the outlet port can be advantageously located at the top of the supply chamber.

[0005] The pump also includes a pumping chamber disposed within or inside the liquid supply chamber, which is in direct fluid communication with the fluid supply chamber. Without loss of generality, this pumping chamber is also referred to as a first pumping chamber or a first-stage chamber. The pump can be configured as a single-stage pump having only one pumping chamber, or as a two-stage or double-stage pump having the first pumping chamber and a second pumping chamber in fluid communication with the first chamber.

[0006] The piston is configured to reciprocate along a motion axis (particularly the longitudinal axis) in a first pumping chamber, such that by means of the piston's reciprocating motion, liquid is transported from a fluid supply chamber to the pumping chamber and pressurized therein. The piston protrudes at least partially from the outside of the fluid supply chamber; that is, a portion of the piston is disposed outside the fluid supply chamber. In particular, the piston may move within a cylinder or sleeve, thereby defining a pumping chamber within that cylinder or sleeve.

[0007] The pump is installed horizontally, so the piston's axis of motion is horizontal.

[0008] According to the invention, a heat shielding unit is provided in the fluid supply chamber at a predetermined location where the piston protrudes from the outside of the fluid supply chamber into the fluid supply chamber. This predetermined location may, for example, correspond to the hot end of the fluid supply chamber. The heat shielding unit is configured to at least partially absorb heat conducted, dissipated, or otherwise intruded into the fluid supply chamber and / or pumping chamber from the outside of the fluid supply chamber (particularly from the ambient atmosphere surrounding the pump). The heat shielding unit is further configured to guide or transfer the absorbed heat to the outlet port, particularly by means of gravity and / or convection.

[0009] Heat from outside the supply chamber can be conducted from the outside to the supply chamber along the piston or along the housing, sleeve, or cylinder in which the piston reciprocates. The heat shield unit is specifically configured to absorb at least a portion of this heat and transfer it to the outlet of the supply chamber. The heat shield unit can be configured, for example, as a specific part, section, or cavity within the fluid supply chamber, such that a certain amount of liquid introduced into the fluid supply chamber can circulate in that specific chamber section. This circulating amount of liquid can then advantageously absorb at least partially the heat conducted from the outside and direct it to the tank return outlet of the supply chamber, thereby shielding the remaining liquid in the fluid supply chamber and pumping chamber. The heat shield unit can also be configured, for example, as a specific element arranged within the supply chamber, such as a foil or plate.

[0010] Therefore, the heat shield unit is specifically configured as a heat screen or liquid screen or heat shield between the external part of the pump and the supply chamber and / or the first pumping chamber. Advantageously, most or any heat intrusion can be absorbed by the heat shield unit, especially by the first liquid in contact, and then guided to the source tank, thus acting as a barrier. In particular, the heat shield unit can significantly prevent this heat from reaching the remaining parts of the supply chamber and the first pumping chamber, where the liquid to be pumped is advantageously in equilibrium, and where any heat could generate bubbles that are detrimental to the efficiency of the pump.

[0011] For efficient operation, cryogenic pumps may particularly require the coldest possible liquid at the suction side. Any heat ingress can reduce the NPSH (Net Positive Suction Head) available during pumping. In conventional cryogenic pumps, thermal bridges may exist between the ambient temperature and the corresponding supply or pumping chamber. This invention specifically allows for the prevention of such thermal bridges, thereby improving the efficiency of the cryogenic pump.

[0012] This invention particularly produces the lower NPSH required by pumps because the pump may be less sensitive to the quality of the suction line and the quality of the liquid in the storage tank in terms of pressure and / or temperature. This invention can further achieve better volumetric efficiency, better isentropic efficiency, and lower discharge temperature. This invention is applicable to all cryogenic gases and all types of reciprocating pumps. This invention is particularly applicable to cryogenic liquids, such as liquid hydrogen (LH2), and is suitable for two-stage pumps.

[0013] It should be understood that the pump may include additional components, such as a discharge outlet configured to discharge liquid pressurized by the reciprocating motion of a piston. In a single-stage pump, the discharge outlet may be in direct fluid communication with the first pumping chamber. In a two-stage pump, the discharge outlet may be in indirect fluid communication with the first pumping chamber via a second pumping chamber. The pump may also include multiple valves, for example, disposed between the liquid supply chamber and the first pumping chamber, and between the first pumping chamber and the discharge outlet.

[0014] According to one embodiment, a heat shield unit is provided as a specific cavity, section, or portion between the housing of the first pumping chamber and the housing of the fluid supply chamber, the section extending in a direction parallel to and / or perpendicular to the axis of motion of the piston's reciprocating motion. This specific section particularly surrounds the piston or the piston housing and extends radially to provide extended heat shielding, particularly extending as far as possible between the axis of motion and the outer housing of the pump or the outer housing of the fluid supply chamber. Alternatively or even additionally, this section extends particularly in a direction parallel to the axis of motion to provide a distance from the first pumping chamber to the outer housing of the pump or to the outer housing of the fluid supply chamber, thereby serving as a means of heat capture and transfer. This section may be specifically configured as a conduit or cavity in which a specific amount of liquid within the fluid supply chamber can circulate, such that the circulated amount of liquid can at least partially absorb heat conducted into the supply chamber and transfer it to the outlet. The heat shield unit and the liquid circulating therein may advantageously serve as a liquid or heat screen.

[0015] According to one embodiment, the thermal shielding unit separates the housing of the first pumping chamber from the housing of the fluid supply chamber in a direction parallel to the axis of motion of the piston's reciprocating motion. A specific section of the supply chamber, which serves as the thermal shielding unit, is specifically used as a heat capture and transfer area between the housings of the fluid supply chamber and the first pumping chamber, ensuring that these housings do not directly contact each other. Therefore, potential thermal bridges from external or ambient air along the piston housing, the supply chamber housing, and the first pumping chamber housing can be effectively interrupted.

[0016] According to one embodiment, the heat shield unit is configured such that the housing of the pumping chamber and the housing of the fluid supply chamber are separated by a predetermined distance in a direction parallel to the axis of motion of the piston's reciprocating motion. The length of a specific section of the fluid supply chamber forming the heat shield unit can be advantageously selected to be this predetermined distance.

[0017] According to one embodiment, the predetermined distance corresponds to at most 5% of the total length of the fluid supply chamber in the direction parallel to the axis of motion of the piston's reciprocating motion. In particular, the predetermined distance can be determined to be large enough, as needed, that the liquid circulating in a particular section can effectively absorb the intruding heat, but at the same time as small as possible to reduce the overall volume of the pump.

[0018] According to one embodiment, the heat shielding unit is configured as a specific heat-conducting element (e.g., foil and / or sheet) disposed between the housing of the first pumping chamber and the housing of the fluid supply chamber. This element may, in particular, surround the piston or the piston housing. The heat-conducting element advantageously absorbs heat conducted from the outside along the piston housing and then transfers the heat out of the supply chamber.

[0019] According to one embodiment, the pump also includes an insulating sheath that at least partially surrounds the liquid supply chamber. The insulating sheath may, for example, be configured as a vacuum chamber. For this purpose, the insulating sheath may include a connection device for connecting the insulating sheath to a vacuum pump, such that a vacuum can be generated inside the insulating sheath.

[0020] According to one embodiment, the piston protrudes from the outside of the insulating sleeve, passes through the insulating sleeve, and enters the fluid supply chamber. A thermal shielding unit is specifically positioned at the point where the piston enters the supply chamber from the insulating sleeve. Therefore, the thermal bridge from the outside along the piston housing through the insulating sleeve into the supply chamber can be advantageously interrupted by means of the thermal shielding unit.

[0021] According to one embodiment, the pump further includes a second pumping chamber or second-stage chamber disposed within or inside the liquid supply chamber, which is in direct fluid communication with the first pumping chamber. By means of the reciprocating motion of a piston, pressurized liquid is conveyed from the first pumping chamber to the second pumping chamber, and further pressurized in the second pumping chamber. A discharge outlet is specifically in direct fluid communication with the second pumping chamber and is configured to discharge pressurized liquid from the second pumping chamber. Advantageously, in the first pumping chamber, the liquid can be compressed to a first pressure level or pressure stage. In the second pumping chamber, the liquid can then be further compressed to a second pressure level or pressure stage. Thus, the pump can be configured as a two-stage or double-stage pump, particularly for compressing cryogenic fluids. For such a two-stage pump, it may be particularly critical that the liquid on the suction side is as cold as possible, especially when the pump is used to compress cryogenic liquids (e.g., liquid hydrogen). Therefore, the present invention is particularly suitable for such double-stage pumps.

[0022] Further advantages and developments of the invention are specified in the description and associated drawings.

[0023] Of course, the features mentioned above and explained below can be used not only in the indicated combinations, but also in other combinations or independently, without departing from the scope of the invention.

[0024] The present invention is schematically illustrated in the accompanying drawings according to exemplary embodiments, and will be described in detail below with reference to the drawings. Attached Figure Description

[0025] Figure 1 An embodiment of the reciprocating pump according to the present invention is schematically shown in a cross-sectional side view.

[0026] Figure 2 A reciprocating pump according to the prior art is schematically shown in a cross-sectional side view. Detailed Implementation

[0027] Figure 1 An embodiment of the cryogenic reciprocating pump 100 according to the present invention is shown in a cross-sectional side view.

[0028] Pump 100 includes a liquid supply chamber, suction chamber, or receiving chamber 110 having an inlet port 111 and an outlet port 112. Inlet 111 may be connected to a storage tank, allowing liquid to be pressurized to be delivered from the storage tank to the liquid supply chamber 110. Heated or vaporized liquid may be discharged from the supply chamber 110 via outlet 112. The liquid may be a cryogenic liquid operating at extremely low temperatures (e.g., below -100°C), such as liquid hydrogen (LH2).

[0029] A first pumping chamber or first-stage chamber 130 is disposed within or inside the liquid supply chamber 110 and is in direct fluid communication with the liquid supply chamber 110. The pump 100 is configured, for example, as a two-stage pump, and further includes a second pumping chamber or second-stage chamber 140 disposed within or inside the liquid supply chamber 110, wherein the second pumping chamber 140 is in direct fluid communication with the first pumping chamber 130. A discharge outlet 150 is in direct fluid communication with the second pumping chamber 140.

[0030] Piston 120 is configured to reciprocate along a motion axis 121 (particularly the longitudinal axis) in a first pumping chamber 130, as indicated by arrow 122. By means of the reciprocating motion 122 of piston 120, liquid is delivered or drawn from fluid supply chamber 110 into the first pumping chamber 130 and pressurized therein, particularly to a first pressure level or pressure stage. The liquid pressurized to this first pressure level is then delivered from the first pumping chamber 130 to a second pumping chamber 140, where it is further pressurized to a second pressure level or pressure stage. The liquid pressurized to this second pressure level is then discharged from pump 100 via discharge outlet 150.

[0031] Pump 100 also includes a plurality of valves 180 disposed between liquid supply chamber 110 and first pumping chamber 130, between first pumping chamber 130 and second pumping chamber 140, and between second pumping chamber 140 and discharge outlet 150.

[0032] The pump 100 also includes an insulating sheath 160 that at least partially surrounds the liquid supply chamber 110. Advantageously, the housing 165 of the insulating sheath 160 surrounds the housing 115 of the fluid supply chamber 110. The insulating sheath 160 may be configured, for example, as a vacuum chamber, such that a vacuum can be created inside the insulating sheath 160 as thermal insulation for the fluid supply chamber 110.

[0033] The piston 120 protrudes at least partially into the fluid supply chamber 110, advantageously protruding from the outside of the insulating sleeve 160 and passing through the insulating sleeve 160 into the fluid supply chamber 110. Within the fluid supply chamber 110, a heat shield unit 170 is provided at a predetermined position 171 where the piston 120 protrudes from the outside into the fluid supply chamber 110. This heat shield unit is configured to at least partially absorb heat, as indicated by arrow 175, which is conducted, dissipated, or intruded from the outside of the fluid supply chamber 110 and / or the first pumping chamber 120. The heat shield unit is further configured to direct the absorbed heat to the outlet port 112, particularly by means of gravity and / or convection.

[0034] The heat shield unit 170 may be provided as a specific cavity, section, or portion of the fluid supply chamber 110 between the housing 135 of the first pumping chamber 130 and the housing 115 of the fluid supply chamber 110, the section extending in a direction parallel to and perpendicular to the axis of motion 121 of the reciprocating motion of the piston 120. This specific section 170 may be provided as a conduit or cavity surrounding the piston 120, in which a specific amount of liquid within the fluid supply chamber 110 may circulate, such that the circulating liquid may at least partially absorb the heat 175 conducted into the supply chamber 110. The heat shield unit 170 and the liquid circulating therein may advantageously serve as a liquid screen. The heat is then transferred to the supply chamber outlet connection 112 by gravity and / or convection.

[0035] With the aid of the thermal shielding unit 170, the housing 135 of the first pumping chamber 130 is separated from the housing 115 of the fluid supply chamber 110 in a direction parallel to the axis of motion 121 of the reciprocating motion of the piston 120, specifically by a predetermined distance. This predetermined distance may, for example, correspond to at most 5% of the total length of the fluid supply chamber 110 in the direction parallel to the axis of motion 121. Therefore, the housing 135 of the first pumping chamber 130 and the housing 115 of the fluid supply chamber 110 are not in direct contact with each other.

[0036] The heat shield unit 170 may also include a heat-conducting element, such as a foil or sheet. The element may surround the piston 120 at a predetermined position 171 between the housing 135 of the first pumping chamber 130 and the housing 115 of the fluid supply chamber 110, such that the element may at least partially conduct heat intrusion 175.

[0037] The thermal shielding unit 170 interrupts or prevents potential thermal bridges from entering the supply chamber 110 and the first pumping chamber 130 from the external or ambient atmosphere along the piston 120 through the insulating sleeve 160, as will now be referred to. Figure 2 The explanation given.

[0038] Figure 2 A reciprocating pump 200 according to the prior art is shown. Figure 2 In, with Figure 1 The components of the reciprocating pump 100 shown are equivalent to those of the reciprocating pump 200 and are used with Figure 1 The value 100 is indicated by an additional reference numeral. To avoid repetition, these elements will not be explained in detail.

[0039] As with Figure 1 Compared to Figure 2 As can be seen, the reciprocating pump 200 according to the prior art does not include a heat shielding unit. The housing 235 of the corresponding first pumping chamber 230 and the housing 215 of the corresponding fluid supply chamber 210 are not separate from each other, but form a common housing.

[0040] Therefore, a thermal bridge exists between the outside and the common housing, as indicated by arrow 275, allowing heat from the ambient atmosphere to dissipate into the first pumping chamber 230 along this thermal bridge, thereby heating the fluid entering the first pumping chamber 230. However, for the pump 200 to operate effectively, it may be important that the liquid delivered from the supply chamber 210 to the first pumping chamber 230 be as cold as possible.

[0041] In contrast, such thermal bridging can be prevented or interrupted by means of the thermal shielding unit 170 according to an embodiment of the invention. Therefore, the present invention can produce a lower NPSH (Net Positive Suction Head) because the corresponding pump 100 may be less sensitive to the quality of the suction line and the quality of the liquid in the storage tank in terms of pressure and / or temperature. The present invention can further achieve better volumetric efficiency, better isentropic efficiency, and lower discharge temperature.

Claims

1. A cryogenic reciprocating pump (100), the cryogenic reciprocating pump comprising: A liquid supply chamber (110) having an inlet port (111) and an outlet port (112) is configured such that the liquid to be pressurized is disposed in the supply chamber; A pumping chamber (130) is arranged within the liquid supply chamber (110) and is in fluid communication with the fluid supply chamber (110); A piston (120) is configured to reciprocate along a motion axis (121) in the pumping chamber (110) such that, by means of the reciprocating motion of the piston (120), liquid is delivered from the fluid supply chamber (110) to the pumping chamber (130) and pressurized in the pumping chamber (130), wherein the piston (120) protrudes at least partially from the outside of the fluid supply chamber (110); wherein the pump is mounted horizontally relative to the motion axis (121) of the piston. Its features A heat shield unit (170) is provided inside the fluid supply chamber (110) at a predetermined position (171) where the piston (120) protrudes from the outside of the fluid supply chamber (110) into the fluid supply chamber (110). The heat shield unit (170) is configured to absorb at least part of the heat (175) conducted from the outside of the fluid supply chamber (110) into the fluid supply chamber (110) and / or into the pumping chamber (130), and to direct the absorbed heat to the outlet port (112).

2. The pump according to claim 1, wherein the heat shield unit (170) is provided as a section of the fluid supply chamber (110) between the housing (135) of the pumping chamber (130) and the housing (115) of the fluid supply chamber (110), the section extending in a direction parallel to the motion axis (121) of the reciprocating motion of the piston (120) and / or in a direction perpendicular to the motion axis (121) of the reciprocating motion of the piston (120).

3. The pump according to claim 1 or 2, wherein the heat shield unit (170) separates the housing (135) of the pumping chamber (130) from the housing (115) of the fluid supply chamber (110) in a direction parallel to the motion axis (121) of the reciprocating motion of the piston (120).

4. The pump according to claim 2 or 3, wherein the heat shield unit (170) is configured such that the housing (135) of the pumping chamber (130) and the housing (115) of the fluid supply chamber (110) are separated by a predetermined distance in the direction parallel to the motion axis (121) of the reciprocating motion of the piston (120).

5. The pump according to claim 4, wherein the predetermined distance corresponds to at most 5% of the length of the fluid supply chamber (110) in the direction parallel to the motion axis (121) of the reciprocating motion of the piston (120).

6. The pump according to any one of the preceding claims, wherein the heat shielding unit (170) is configured as a heat conduction element, the heat conduction element being disposed between the housing (135) of the pumping chamber (130) and the housing (115) of the fluid supply chamber (110).

7. The pump according to any one of the preceding claims, the pump further comprising an insulating sheath (160) that at least partially surrounds the liquid supply chamber (110).

8. The pump according to claim 7, wherein the piston (170) protrudes from the outside of the insulating sleeve (160) through the insulating sleeve (160) into the fluid supply chamber (110).

9. The pump according to any one of the preceding claims, the pump further comprising a second pumping chamber (140) disposed within the liquid supply chamber (110) and in fluid communication with the pumping chamber (130), such that pressurized liquid is delivered from the pumping chamber (130) to the second pumping chamber (140) and further pressurized in the second pumping chamber (140) by means of the reciprocating motion of the piston (120).

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