Nitrogen online supply system

Abstract

The present application provides a kind of nitrogen online gas supply system, belong to nitrogen gas supply technical field, comprising: liquid nitrogen tank, liquid nitrogen plunger pump and vaporizer being sequentially arranged, the liquid nitrogen plunger pump has and is arranged at least two, and frequency converter is arranged on the drive device of each liquid nitrogen plunger pump;The nitrogen online gas supply system of the present application carries out high pressure online gas supply with liquid nitrogen plunger pump as core power, liquid nitrogen is pressurized by liquid nitrogen plunger pump, directly supplied to gas unit after vaporization, without setting a large number of high-pressure gas cylinder, can effectively solve the problem of high investment of gas cylinder gas supply system;And, by the combination of multiple liquid nitrogen plunger pumps, each pump uses frequency conversion regulation, effectively solve the problem of equipment adaptability under the condition of severe load variation.

Description

TECHNICAL FIELD

[0001] The present application relates to nitrogen gas supply technology field, specifically relates to a kind of nitrogen online gas supply system. BACKGROUND

[0002] The original 35-45MPa high-pressure nitrogen supply in aerospace field needs to be operated in long-term variable working condition, and high-pressure gas cylinder supply mode is usually adopted, that is, the gas in the high-pressure gas cylinder is filled first, then the quality of the gas in the cylinder is tested and confirmed, and finally the high-pressure gas cylinder and pipeline are used to supply gas to the gas-consuming unit.

[0003] With the advent of large-scale cryogenic launch vehicles, the demand for high-pressure nitrogen is increasing, and the problems of high construction cost and safety of pressure vessels caused by high-pressure gas cylinder supply mode are becoming more and more prominent. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to overcome the defect that the nitrogen supply in the prior art needs to use high-pressure gas cylinder to store gas, thereby providing a nitrogen online gas supply system.

[0005] In order to solve the above technical problems, the present application provides a nitrogen online gas supply system, comprising: liquid nitrogen tank, liquid nitrogen plunger pump and vaporizer arranged in sequence, the liquid nitrogen plunger pump has at least two parallel arranged, and a frequency converter is arranged on the driving device of each liquid nitrogen plunger pump.

[0006] Optionally, it further comprises a controller, which is electrically connected with the driving device of the liquid nitrogen plunger pump.

[0007] Optionally, a first reflux pipeline is connected to the liquid nitrogen plunger pump, a first electric control valve is arranged on the first reflux pipeline, and the first electric control valve is electrically connected with the controller.

[0008] Optionally, a first temperature sensor is arranged on the liquid nitrogen plunger pump, and a second temperature sensor is arranged on the outlet pipeline of the liquid nitrogen plunger pump, and the first temperature sensor and the second temperature sensor are respectively electrically connected with the controller.

[0009] Optionally, a pressure sensor is arranged on the outlet pipeline of the liquid nitrogen plunger pump, and the pressure sensor is electrically connected with the controller.

[0010] Optionally, a second reflux pipeline circulating towards the liquid nitrogen tank is arranged on the pipeline leading from the outlet of the liquid nitrogen plunger pump to the vaporizer, a second electric control valve is arranged on the second reflux pipeline, and the second electric control valve is electrically connected with the controller.

[0011] Optionally, a third electric control valve is arranged at the inlet of each vaporizer, and the third electric control valve is electrically connected with the controller.

[0012] Optionally, the liquid nitrogen tank has a flat-bottom structure, and each liquid nitrogen plunger pump is individually connected to the flat-bottom structure of the liquid nitrogen tank via a pipeline.

[0013] Optionally, the vaporizer has two arrays arranged symmetrically.

[0014] Optionally, an electric heater is connected to the outlet pipe of the vaporizer.

[0015] The technical solution of this invention has the following advantages:

[0016] 1. The nitrogen online gas supply system provided by this invention uses a liquid nitrogen plunger pump as the core power source for high-pressure online gas supply. After being pressurized and vaporized by the liquid nitrogen plunger pump, the liquid nitrogen is directly supplied to the gas-consuming unit, eliminating the need for a large number of high-pressure gas storage cylinders and effectively solving the problem of high investment in gas cylinder supply systems. Furthermore, by combining multiple liquid nitrogen plunger pumps, each pump adopts frequency conversion regulation, effectively solving the problem of equipment adaptability under drastic changes in gas load.

[0017] 2. The nitrogen online supply system provided by the present invention uses a flat-bottomed liquid nitrogen tank and solves the problems of multiple pumps sharing a single supply pipe and thus causing multiple blind branches that are prone to cavitation by using a single pump and a single pipe to supply multiple liquid nitrogen plunger pumps.

[0018] 3. The nitrogen online gas supply system provided by the present invention has a first return pipe on the liquid nitrogen plunger pump and a second return pipe at the outlet of the liquid nitrogen plunger pump. It adopts a process combining low-pressure circulating cooling and high-pressure circulating cooling, which effectively solves the problem of easy cavitation when the liquid nitrogen plunger pump is kept cold under intermittent operating conditions.

[0019] 4. The nitrogen online gas supply system provided by the present invention has multiple vaporizers arranged symmetrically, which can effectively solve the problem of preventing flow deviation.

[0020] 5. The nitrogen online gas supply system provided by the present invention solves the safety problem of on-site operation by using a remote control method. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of an online nitrogen supply system provided in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Liquid nitrogen tank; 2. Liquid nitrogen plunger pump; 3. Vaporizer; 4. First reflux pipe; 5. Second reflux pipe; 6. First solenoid valve; 7. Second solenoid valve; 8. First temperature sensor; 9. Second temperature sensor; 10. Electric heater; 11. Third solenoid valve; 12. Motor; 13. Frequency converter. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The nitrogen online supply system provided in this embodiment is suitable for online supply of high-flow-rate, high-pressure nitrogen under long-term variable operating conditions, and can be used in the aerospace field for 35-45MPa high-pressure nitrogen supply.

[0030] like Figure 1The diagram illustrates a specific implementation of the online nitrogen supply system provided in this embodiment, comprising: a large-capacity flat-bottomed liquid nitrogen tank 1, a liquid nitrogen plunger pump 2, and a vaporizer 3 arranged sequentially. Multiple vaporizers are arranged in parallel. Under large-volume supply conditions, due to the limited manufacturing volume of a single vaporizer, multiple sets of liquid nitrogen vaporizers 3 operating in parallel can meet the liquid nitrogen output of the large liquid nitrogen plunger pump. Alternatively, as an alternative implementation, without considering volumetric costs, only one set of vaporizers may be used.

[0031] like Figure 1 As shown, the nitrogen online gas supply system provided in this embodiment includes multiple liquid nitrogen plunger pumps 2 arranged in parallel, with the outlet of each liquid nitrogen plunger pump 2 connected to a corresponding vaporizer group. Each vaporizer group has multiple vaporizers 3 arranged in parallel, and a third electrically controlled valve 11 is installed at the inlet of each vaporizer 3. The third electrically controlled valve 11 is electrically connected to the controller, and the outlets of the multiple vaporizers 3 converge and connect to the gas-consuming unit. The vaporizer groups are arranged in symmetrical double groups, with each group containing a symmetrical even number of vaporizers 3. This multi-layer, fully symmetrical arrangement of the vaporizers 3 ensures uniformity of the flow distribution at each stage, effectively preventing flow deviation and ensuring the vaporization effect of the liquid nitrogen.

[0032] like Figure 1 As shown, in the nitrogen online gas supply system provided in this embodiment, the driving device for the liquid nitrogen plunger pump 2 can be a motor 12. A frequency converter 13 is installed on the driving device of the liquid nitrogen plunger pump 2. After multiple liquid nitrogen plunger pumps 2 are combined, the adaptability problem of the equipment under drastic changes in gas load can be effectively solved by adjusting the frequency of each liquid nitrogen plunger pump. Specifically, due to the limitations of the operating characteristics of the liquid nitrogen plunger pump 2, a single liquid nitrogen plunger pump 2 can adjust the load within a range of 40% to 100%. When multiple liquid nitrogen plunger pumps are combined, taking five pumps as an example, the adjustment precision of 0%, 20%, 40%, 60%, 80%, and 100% can be achieved by combining the number of pumps. Then, by adjusting the frequency of each pump, the adjustment precision can be further improved to 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%, achieving a gas volume adjustment accuracy within 10%. If each pump is further finely adjusted and combined, an even finer adjustment effect can be achieved.

[0033] like Figure 1As shown, in the nitrogen online supply system provided in this embodiment, the inlet of each liquid nitrogen plunger pump 2 is connected to the liquid nitrogen tank 1 via a liquid inlet pipe. The liquid nitrogen tank 1 has a flat-bottom structure, and the liquid inlet pipe is vertically connected to the flat-bottom structure. The liquid nitrogen tank 1 with a flat-bottom structure can be assembled on-site, and its capacity is not limited. Therefore, it can be manufactured with a large capacity according to the design to achieve dedicated single-pump single-pipe supply for multiple liquid nitrogen plunger pumps 2, solving the problem of multiple blind branches and easy cavitation caused by multiple pumps sharing a single liquid supply pipe. On the other hand, connecting the liquid inlet pipe to the flat-bottom structure of the liquid nitrogen tank 1 can minimize the flow distance from the liquid nitrogen tank 1 to the liquid nitrogen plunger pump 2, reduce bends, back slopes, and other links, and further prevent cavitation from occurring.

[0034] The liquid nitrogen plunger pump 2 provided in this embodiment is a reciprocating machine that relies on piston motion to pressurize liquid. During operation, it generates compression heat, frictional heat, and external heat leakage. Once liquid nitrogen vaporizes in the pump chamber (i.e., cavitation), most of the effective work of the motor will be wasted on the compression of the gas, and the pressurization effect will immediately decrease or even be largely lost. Maintaining the liquid nitrogen plunger pump 2 in a cold state is an important way to overcome cavitation. During the operation of the liquid nitrogen plunger pump 2, especially during long-term intermittent operation, the pump temperature is in an unsteady state, making it more prone to pump body warming up and thus cavitation.

[0035] In this embodiment, the cooling process of the liquid nitrogen plunger pump 2 employs a combination of low-pressure and high-pressure circulation cooling. The former uses a low-pressure circulation mode where the pump chamber outside the pump head is connected to the storage tank, while the latter uses a high-pressure circulation cooling mode where high-pressure liquid nitrogen from the high-pressure side outlet of the pump head returns to the storage tank. This combination allows for combined cooling from both inside and outside the pump head, ensuring the pump head remains cold and effectively preventing cavitation. Compared to venting methods, regardless of whether it's low-pressure or high-pressure circulation, all the medium returns to the storage tank, reducing liquid nitrogen waste and ensuring the safety of the on-site environment.

[0036] like Figure 1 As shown, the nitrogen online supply system provided in this embodiment includes a liquid nitrogen plunger pump 2 comprising a housing and a cylinder disposed within the housing. The cylinder has an inlet leading to the housing, and a plunger is disposed within the cylinder. The housing of the liquid nitrogen plunger pump 2 is provided with a first return pipe 4 circulating towards the liquid nitrogen tank 1, and a first electrically controlled valve 6 is disposed on the first return pipe 4. When liquid nitrogen flows from the liquid nitrogen tank 1 into the housing of the liquid nitrogen plunger pump 2, a portion of the liquid nitrogen vaporizes. This vaporized portion can flow back to the liquid nitrogen tank 1 through the first return pipe 4, thereby ensuring the cooling of the liquid nitrogen plunger pump 2 and effectively preventing cavitation of the liquid nitrogen plunger pump 2.

[0037] like Figure 1As shown, in the nitrogen online gas supply system provided in this embodiment, a second return pipe 5 is provided on the pipe leading from the outlet of the liquid nitrogen plunger pump 2 to the vaporizer, circulating towards the liquid nitrogen tank 1. A second electrically controlled valve 7 is installed on the second return pipe 5. The vaporized liquid nitrogen in the liquid nitrogen plunger pump 2 can be returned to the liquid nitrogen tank 1 through the second return pipe 5, thereby eliminating gas accumulation in the liquid nitrogen plunger pump 2, preventing cavitation, and simultaneously cooling the system. By setting up the first and second return pipes 5, and adopting a combination of low-pressure and high-pressure circulating cooling processes, the problem of easy cavitation when the liquid nitrogen plunger pump is kept cold under intermittent operating conditions is effectively solved. The first electrically controlled valve 6 and the second electrically controlled valve 7 are respectively connected to a controller, which can remotely control the first electrically controlled valve 6 and the second electrically controlled valve 7. The first electrically controlled valve 6 and the second electrically controlled valve 7 can be pneumatic valves.

[0038] like Figure 1 As shown in the figure, the nitrogen online supply system provided in this embodiment includes a first temperature sensor 8 on the liquid nitrogen plunger pump 2 and a second temperature sensor 9 on the outlet pipe of the liquid nitrogen plunger pump 2. The first temperature sensor 8 and the second temperature sensor 9 are electrically connected to the controller. The controller remotely monitors the temperature of two key components of the liquid nitrogen plunger pump 2 through the first temperature sensor 8 and the second temperature sensor 9. The controller can automatically remotely control each electrically controlled valve in the nitrogen online supply system. In case of cavitation, if the first temperature sensor 8 and the second temperature sensor 9 show abnormally high readings, a low-pressure and high-pressure circulating cooling process is activated to quickly eliminate cavitation.

[0039] like Figure 1 As shown in the figure, the nitrogen online gas supply system provided in this embodiment has a pressure sensor installed on the outlet pipe of the liquid nitrogen plunger pump 2. The pressure sensor is electrically connected to the controller. The controller monitors the pressure on the outlet pipe of the liquid nitrogen plunger pump 2 through the pressure sensor. Then, the system pressure can be adjusted by controlling the number and frequency of operation of the electrically controlled valves and pumps in the nitrogen online gas supply system. The controller can be a PLC controller to realize remote control and solve the safety problem of on-site operation.

[0040] like Figure 1 As shown, the nitrogen online supply system provided in this embodiment has an outlet temperature that is more than 10°C lower than the ambient temperature because the vaporizer uses air as the heating medium. Therefore, an electric heater 10 is connected to the outlet pipe of the vaporizer. This electric heater 10 can effectively solve the problem of excessively low outlet nitrogen temperature during winter operation. The electric heater 10 is electrically connected to a controller, meaning that the controller can remotely control the switching on and off of the electric heater 10 or adjust its power to ensure a suitable supply temperature and the safety of downstream equipment.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A nitrogen online supply system, characterized in that, include: The liquid nitrogen tank (1), liquid nitrogen plunger pump (2) and vaporizer (3) are arranged in sequence. The liquid nitrogen plunger pump (2) has at least two units arranged in parallel, and each liquid nitrogen plunger pump (2) is equipped with a frequency converter (13) on its drive device. The liquid nitrogen plunger pump (2) has a first return pipe (4) on its housing that circulates toward the liquid nitrogen tank (1), and the vaporized liquid nitrogen flows back into the liquid nitrogen tank (1) through the first return pipe (4); the outlet of the liquid nitrogen plunger pump (2) leading to the vaporizer (3) has a second return pipe (5) that circulates toward the liquid nitrogen tank (1), and the vaporized liquid nitrogen in the liquid nitrogen plunger pump (2) flows back into the liquid nitrogen tank (1) through the second return pipe (5); The liquid nitrogen tank (1) has a flat bottom structure, and each liquid nitrogen plunger pump (2) is individually connected to the flat bottom structure of the liquid nitrogen tank (1) through a pipeline. The low-pressure circulation mode, which connects the pump chamber outside the pump head to the storage tank, and the high-pressure circulation cooling mode, which uses high-pressure liquid nitrogen from the high-pressure side outlet of the pump head to return to the storage tank, are combined to ensure that the pump head is kept cold and prevent cavitation of the liquid nitrogen plunger pump (2).

2. The nitrogen online supply system according to claim 1, characterized in that, Also includes: The controller is electrically connected to the drive unit of the liquid nitrogen plunger pump (2).

3. The nitrogen online supply system according to claim 2, characterized in that, A first electrically controlled valve (6) is provided on the first return pipe (4), and the first electrically controlled valve (6) is electrically connected to the controller.

4. The nitrogen online supply system according to claim 2, characterized in that, The liquid nitrogen plunger pump (2) is equipped with a first temperature sensor (8) and a second temperature sensor (9) is equipped on the outlet pipe of the liquid nitrogen plunger pump (2). The first temperature sensor (8) and the second temperature sensor (9) are electrically connected to the controller respectively.

5. The nitrogen online supply system according to claim 2, characterized in that, A pressure sensor is provided on the outlet pipe of the liquid nitrogen plunger pump (2), and the pressure sensor is electrically connected to the controller.

6. The online nitrogen supply system according to claim 2, characterized in that, A second electrically controlled valve (7) is provided on the second return pipe (5), and the second electrically controlled valve (7) is electrically connected to the controller.

7. The online nitrogen supply system according to claim 2, characterized in that, At the inlet of each of the vaporizers (3), a third electrically controlled valve (11) is provided, which is electrically connected to the controller.

8. The online nitrogen supply system according to claim 1, characterized in that, The vaporizer (3) has a symmetrically arranged double array.

9. The nitrogen online supply system according to any one of claims 1-8, characterized in that, An electric heater (10) is connected to the outlet pipe of the vaporizer (3).

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