Circulation loop and cryogenic liquid transport / filling device including the circulation loop

Abstract

The present invention discloses a circulation loop and a cryogenic liquid transport / filling device including the circulation loop, and relates to the field of cryogenic liquid transport / filling technology. The circulation loop is used to be installed on a cryogenic liquid transport / filling device, and the cryogenic liquid transport / filling device includes a cryogenic liquid storage tank and a delivery pump connected to the cryogenic liquid storage tank; the circulation loop includes a one-way valve, a reflux pipe, and a vaporization device for vaporizing the cryogenic liquid in the reflux pipe, the reflux pipe is connected to the outlet end of the one-way valve, the inlet end of the one-way valve is connected to the outlet end of the delivery pump, and the outlet end of the reflux pipe or the vaporization device is connected to the cryogenic liquid storage tank. The beneficial effect of the present invention is that it can not only keep the pressure inside the cryogenic liquid storage tank stable, but also can realize the effect of pressurizing the cryogenic liquid storage tank, so as to avoid the delivery pump from stopping working due to cavitation. The circulation loop in the present invention has a simple structure, low production cost, and is easy to use.

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic liquid transportation / filling, in particular to a circulation loop and a cryogenic liquid transportation / filling device comprising the circulation loop. Background Art

[0002] In the prior art, cryogenic liquids such as liquid nitrogen are generally transported or transferred using cryogenic liquid pump trucks. During the transportation or transfer of the cryogenic liquid, the cryogenic liquid needs to be pressurized by a cryogenic pump, so that the pressurized cryogenic liquid can be filled into other transportation or storage equipment.

[0003] Since the liquefied gas transported by the cryogenic pump is usually in a saturated state (or has a slight degree of subcooling), the vapor pressure of this liquid changes significantly with temperature. For example, when the temperature rises, the vapor pressure will increase sharply, the density will decrease, the specific heat capacity will increase, and the latent heat of evaporation will decrease, making the liquefied gas easier to vaporize, resulting in an increase in pressure at the pump inlet, thereby affecting the strength of the pump body; for example, when the temperature drops too much, the steam pressure in the pump pool will drop accordingly, and when flowing through the suction pipeline, it is also easy to absorb heat from the outside and heat up, which will cause the pump cavitation margin to decrease and the suction cavitation performance to deteriorate. Therefore, the subcooling pressure of the cryogenic pump needs to be stabilized during use.

[0004] In the process of pressurizing the cryogenic liquid through a pump and then filling it into other transportation or storage equipment, on the one hand, as the cryogenic liquid in the cryogenic liquid storage tank is discharged, the pressure in the cryogenic liquid storage tank will decrease, resulting in unstable pressure in the cryogenic liquid storage tank; on the other hand, since the pump will generate heat when working, the temperature in the pump pool will rise, causing the cryogenic liquid in the pump pool to vaporize too quickly, and the gas phase space will increase, which will cause cavitation in the pump and the pump will stop working. Summary of the invention

[0005] The object of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a circulation loop and a cryogenic liquid transport / filling device including the circulation loop.

[0006] The technical solution of the present invention is as follows:

[0007] A circulation loop is used to be installed on a cryogenic liquid transport / filling device, which includes a cryogenic liquid storage tank and a delivery pump; the circulation loop includes a one-way valve, a reflux pipe, and a vaporization device for vaporizing the cryogenic liquid in the reflux pipe, the reflux pipe is connected to the outlet end of the one-way valve, the inlet end of the one-way valve is connected to the outlet end of the delivery pump, and the outlet end of the reflux pipe or the vaporization device is connected to the cryogenic liquid storage tank.

[0008] Preferably, the vaporization device is a throttling device for throttling, and the throttling device is arranged in the return pipe along the radial direction.

[0009] Preferably, the throttling device is a throttling orifice plate having a penetrating throttling hole.

[0010] Preferably, the throttling hole is located at the center of the throttling hole plate.

[0011] Preferably, the diameter of the throttle hole is 2.5-4.5 mm.

[0012] Preferably, the outlet end of the reflux pipe is connected to the top of the cryogenic liquid storage tank.

[0013] A cryogenic liquid transport / filling device comprises the above-mentioned circulation loop.

[0014] Preferably, it comprises a cryogenic liquid storage tank, a pump pool, a delivery pump and a filling pipeline connected in sequence, the delivery pump is arranged in the pump pool, and the filling pipeline has a cryogenic liquid outlet; the inlet end of the circulation loop is connected to the outlet end of the delivery pump, and the outlet end is connected to the cryogenic liquid storage tank.

[0015] Preferably, the difference between the gas pressure in the cryogenic liquid storage tank after reflow through the circulation loop and its initial gas pressure is greater than or equal to 68.95 kPa.

[0016] Preferably, the flow rate of the cryogenic liquid outlet is less than 7.8 m 3 / h.

[0017] The beneficial effects of the present invention are as follows: by adding a circulation loop structure to the cryogenic liquid transport / filling device, the present invention enables part of the cryogenic liquid coming out of the delivery pump to return to the circulation loop, and through the throttling effect of the throttling orifice plate in the circulation loop structure, part of the cryogenic liquid in the circulation loop is vaporized during the flow process, and the cryogenic liquid and the vaporized cryogenic liquid are mixed and returned to the top of the cryogenic liquid storage tank, which can not only keep the pressure inside the cryogenic liquid storage tank stable, but also realize the effect of pressurizing the cryogenic liquid storage tank, thereby preventing the delivery pump from cavitation and stopping working. The circulation loop structure of the present invention is simple, the production cost is low, and it is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the circulation loop in the preferred embodiment of the present invention;

[0019] Figure 2 for Figure 1 Middle AA section view;

[0020] Figure 3It is a partial structural schematic diagram of a cryogenic liquid transport device in a preferred embodiment of the present invention;

[0021] Markings in the figure: 11, one-way valve; 12, return pipe; 13, throttling orifice plate; 14, throttling hole; 21, cryogenic liquid storage tank; 22, delivery pump; 23, pump pool; 24, filling pipeline; 25, cryogenic liquid outlet; 26, pump outlet valve; 27, outer cylinder; 28, interlayer; 29, return air pipe. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with specific examples, but the present invention is not limited to the following specific examples.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0025] like Figures 1-2The circulation loop in this embodiment is shown, and the circulation loop includes a one-way valve 11, a return pipe 12, and a vaporization device for vaporizing the cryogenic liquid in the return pipe 12. The inlet end of the return pipe 12 is connected to the outlet end of the one-way valve 11. In this embodiment, the vaporization device is a throttling device, and the throttling device can be a throttling plate with a slit or an orifice. Specifically, in this embodiment, the throttling device is a throttling orifice plate 13, which is embedded in the return pipe 12 along the radial direction. The throttling orifice plate 13 has a throttling hole 14 that penetrates, and the return pipe 12 is throttled through the throttling orifice plate 13. In practical applications, the vaporization device can be a vaporizer, and the specific technicians in this field can determine it according to the actual situation. The throttling hole 14 is located at the center of the throttling orifice plate 13, so that the cryogenic liquid can pass through the throttling hole 14. In practical applications, the throttling hole 14 can also be not located at the center of the throttling orifice plate 13, and the specific technicians in this field can determine it according to the actual situation. In this embodiment, the diameter of the throttling hole 14 is 3.5 mm, which can allow the cryogenic liquid to pass through the throttling hole 14 at a suitable speed. In practical applications, the diameter of the throttling hole 14 can also be 2.5 mm, 3 mm, 4 mm or 4.5 mm, and the specific diameter can be determined by technical personnel in this field according to actual conditions.

[0026] like Figure 3The figure shows a partial structural schematic diagram of the cryogenic liquid transport device in this embodiment. The above-mentioned circulation loop is used to be installed on the cryogenic liquid transport device, such as a cryogenic liquid transport vehicle. In actual applications, the circulation loop can also be used to be installed on a cryogenic liquid filling device, that is, to fill the cryogenic liquid in the storage tank into other storage equipment. The specific details can be determined by those skilled in the art according to actual conditions. The cryogenic liquid transport device includes a cryogenic liquid storage tank 21, a pump pool 23, a delivery pump 22, a filling pipeline 24 and a circulation loop. The cryogenic liquid storage tank 21 is used to store cryogenic liquids, such as liquid nitrogen. An outer cylinder 27 is also sleeved on the outer wall of the cryogenic liquid storage tank 21, and an interlayer 28 is arranged between the outer cylinder 27 and the cryogenic liquid storage tank 21, so that the cryogenic liquid storage tank 21 is insulated by the outer cylinder 27 and the interlayer 28. The pump pool 23 is connected to the bottom of the cryogenic liquid storage tank 21 through a pipeline, so that the cryogenic liquid storage tank 21 can be sucked into the pump pool 23. The upper end of the pump pool 23 is also connected to the top of the cryogenic liquid storage tank 21 through a return pipe 29, so that the vaporized cryogenic liquid in the pump pool 23 returns to the cryogenic liquid storage tank 21 through the return pipe 29. The delivery pump 22 is arranged at the bottom of the pump pool 23 and contacts the cryogenic liquid in the pump pool 23. The outlet end of the delivery pump 22 is connected to the filling pipeline 24 and the circulation loop through a liquid outlet pipe, and a pump outlet valve 26 for controlling the on-off of the liquid outlet pipe is also provided on the liquid outlet pipe; the filling pipeline 24 has a low-temperature liquid outlet 25, and the low-temperature liquid in the pump pool 23 is pressurized by the delivery pump 22, and the pressurized low-temperature liquid is delivered to the filling pipeline 24, and other transportation or storage equipment can be filled with low-temperature liquid through the low-temperature liquid outlet 25; the inlet end of the circulation loop is connected to the liquid outlet pipe, and the outlet end is connected to the low-temperature liquid storage tank 21. Specifically, the inlet end of the one-way valve 11 is connected to the outlet end of the liquid outlet pipe through a pipeline, and the outlet end of the reflux pipe 12 is connected to the top of the low-temperature liquid storage tank 21, which is used to reflux part of the low-temperature liquid in the liquid outlet pipe to the low-temperature liquid storage tank 21. In this embodiment, the difference between the air pressure in the cryogenic liquid storage tank 21 after the circulation loop is refluxed and the initial air pressure in the cryogenic liquid storage tank 21 is greater than or equal to 68.95 kPa, that is, after the circulation loop is refluxed, the air pressure in the cryogenic liquid storage tank 21 is at least 68.95 kPa greater than the initial air pressure. Since the initial cryogenic liquid in the cryogenic liquid storage tank 21 will be partially vaporized, there are both liquid-phase cryogenic liquid and gas-phase cryogenic liquid in the cryogenic liquid storage tank 21. At this time, the liquid-phase cryogenic liquid is a saturated liquid, and the initial air pressure of the cryogenic liquid storage tank 21 is the air pressure of the gas-phase cryogenic liquid. When part of the vaporized cryogenic liquid is refluxed through the circulation loop, the air pressure of the cryogenic liquid storage tank 21 is the sum of the air pressure of the initial cryogenic liquid and the air pressure of the refluxed vaporized cryogenic liquid, thereby preventing the delivery pump 22 from cavitation during the cryogenic liquid filling process. In this embodiment, the flow rate of the cryogenic liquid outlet 25 is less than 7.8 m 3 / h, so that the circulation loop can return part of the cryogenic liquid in the liquid outlet pipe to the cryogenic liquid storage tank 21, which can not only keep the pressure inside the cryogenic liquid storage tank 21 stable, but also can achieve the effect of pressurizing the cryogenic liquid storage tank 21, thereby avoiding cavitation of the delivery pump 22.

[0027] In this embodiment, a circulation loop structure is added to the cryogenic liquid transportation device so that part of the cryogenic liquid coming out of the delivery pump 22 can return to the circulation loop. Through the throttling effect of the throttling orifice plate 13 in the circulation loop structure, part of the cryogenic liquid in the circulation loop is vaporized during the flow, and the cryogenic liquid and the vaporized cryogenic liquid are mixed and returned to the top of the cryogenic liquid storage tank 21. This can not only keep the pressure inside the cryogenic liquid storage tank 21 stable, but also achieve the effect of pressurizing the cryogenic liquid storage tank 21, thereby avoiding cavitation of the delivery pump 22.

[0028] The above are only examples of the features of the present invention and do not constitute any limitation on the protection scope of the present invention. Any technical solution formed by equivalent exchange or equivalent replacement falls within the protection scope of the present invention.

Claims

1. A cryogenic liquid transport / filling device, characterized in that: The invention relates to a cryogenic liquid storage tank (21), a pump pool (23), a delivery pump (22), a filling pipe (24) and a circulation loop which are connected in sequence. The delivery pump (22) is arranged in the pump pool (23). The filling pipe (24) has a cryogenic liquid outlet (25). The inlet end of the circulation loop is connected to the outlet end of the delivery pump (22), and the outlet end is connected to the cryogenic liquid storage tank (21). The circulation loop comprises a one-way valve (11), a return pipe (12) and a vaporizing device for vaporizing the cryogenic liquid in the return pipe (12). The return pipe (12) is connected to the outlet end of the one-way valve (11), the inlet end of the one-way valve (11) is connected to the outlet end of the delivery pump (22), and the return pipe (12) or the vaporizing device is connected to the one-way valve (11). The outlet end of the vaporization device is connected to the cryogenic liquid storage tank (21); the vaporization device is a throttling device for throttling; the throttling device is arranged in the return pipe (12) along the radial direction; the throttling device is a throttling orifice plate (13); the throttling orifice plate (13) has a throttling hole (14) penetrating therethrough; the flow rate of the cryogenic liquid outlet (25) is less than 7.8 m³ / h; the throttling hole (14) is located at the center of the throttling orifice plate (13); the diameter of the throttling hole (14) is 2.5 to 4.5 mm; the outlet end of the return pipe (12) is connected to the top of the cryogenic liquid storage tank (21); the difference between the gas pressure in the cryogenic liquid storage tank after reflux through the circulation loop and its initial gas pressure is greater than or equal to 68.95 kPa.

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