A gas replenishment system for large-flow instantaneous discharge of liquid nitrogen storage tanks

Abstract

The present invention belongs to the technical field of cryogenic storage tanks, and discloses a gas replenishment system for a liquid nitrogen storage tank with large flow rate instantaneous discharge, comprising a liquid inlet device, a liquid discharge device, a self-pressurizing gas replenishment system, an external gas replenishment system, and an exhaust system. The external gas replenishment system is always in working condition, and there is no need to wait for the reaction time of the self-pressurizing gas replenishment system. It can respond quickly, vaporize the liquid nitrogen in the vacuum storage tank and fill it into the liquid nitrogen storage tank to replenish the tank pressure of the liquid nitrogen storage tank. After the self-pressurizing gas replenishment system starts working, it can reduce the adjustment time of the pressure in the storage tank; at the same time, the exhaust system automatically discharges gas after the pressure exceeds the set value, so that the storage tank pressure quickly reaches a stable state. The gas replenishment system for liquid nitrogen storage tank with large flow rate instantaneous discharge of the present invention can ensure that the pressure in the tank is quickly replenished and kept constant when the liquid nitrogen storage tank is discharged instantaneously at a large flow rate, prevent the occurrence of negative pressure and overpressure phenomena, and ensure the working stability and equipment safety of the liquid nitrogen storage tank system.

Description

Technical Field

[0001] The invention belongs to the technical field of cryogenic storage tanks, and in particular relates to a gas replenishing system for a liquid nitrogen storage tank with large flow rate instantaneous discharge. Background Art

[0002] Liquid nitrogen plays a vital role in industrial manufacturing. With the development of society, the demand for liquid nitrogen is increasing. Simultaneously, the storage of liquid nitrogen has driven the development of cryogenic storage tank technology. Furthermore, with the widespread use of high-flow cryogenic pumps, the need for high-flow cryogenic liquid delivery and discharge is increasing. For large-capacity cryogenic storage tanks, high-flow, high-speed discharge can create negative pressure within the tank, seriously impacting operational stability and equipment safety.

[0003] Currently, large-capacity cryogenic storage tanks typically incorporate a self-pressurizing and air-supplementing system. Liquid nitrogen is drawn from the bottom into a vaporizer, which vaporizes the liquid nitrogen and then fills it into the large-capacity cryogenic storage tank, replenishing the tank's internal pressure and regulating it. However, this self-pressurizing and air-supplementing system exhibits a certain degree of hysteresis and a relatively long response time, making it difficult to meet the practical requirements of high-flow, instantaneous discharge of liquid nitrogen from storage tanks.

[0004] Currently, there is an urgent need to develop a gas replenishment system for large-flow instantaneous discharge of liquid nitrogen storage tanks. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a gas replenishing system for a liquid nitrogen storage tank with large flow rate instantaneous discharge, so as to overcome the defects of the prior art.

[0006] The present invention provides a gas replenishment system for high-flow instantaneous discharge of liquid nitrogen from a storage tank. The liquid nitrogen storage tank is provided with a liquid inlet device, which includes a manual stop valve V1 and supporting pipelines. The inlet end of the manual stop valve V1 is connected to a fractionation tower cold box, and the outlet end is connected to a port B at the top of the liquid nitrogen storage tank. The liquid nitrogen storage tank is provided with a liquid discharge device, which includes a cryogenic liquid pump and supporting pipelines. The inlet end of the cryogenic liquid pump is connected to a port E at the bottom of the liquid nitrogen storage tank, and the outlet end is connected to a user. The gas replenishment system for high-flow instantaneous discharge of liquid nitrogen from a storage tank comprises a self-pressurized gas replenishment system, an external gas replenishment system, and an exhaust system.

[0007] The inlet of the manual shut-off valve V4 of the self-pressurized air supply system is connected to port C on the top of the liquid nitrogen storage tank via a supporting pipeline, and the outlet is connected to pressure transmitter II. Pressure transmitter II transmits the control signal to the automatic regulating valve V6 via a signal line. The inlet of the automatic regulating valve V6 is connected to port F at the bottom of the liquid nitrogen storage tank via a supporting pipeline. The outlet of the automatic regulating valve V6 is connected to the inlet of vaporizer II via a supporting pipeline. The outlet of vaporizer II is connected to port D on the top of the liquid nitrogen storage tank via a supporting pipeline.

[0008] Liquid nitrogen is stored in a vacuum storage tank of the external air supply system. The inlet of vaporizer I is connected to the bottom port of the vacuum storage tank through a supporting pipeline, and the outlet is connected to the inlet of automatic regulating valve V5 through a supporting pipeline. The outlet of automatic regulating valve V5 is connected to the inlet of manual stop valve V2 through a supporting pipeline, and the outlet of manual stop valve V2 is connected to port A on the top of the liquid nitrogen storage tank through a supporting pipeline. The inlet of manual stop valve V3 is connected to the outlet pipeline of automatic regulating valve V5 through a supporting pipeline, and the outlet of manual stop valve V3 is connected to pressure transmitter I through a supporting pipeline. Pressure transmitter I transmits the control signal to automatic regulating valve V5 through a signal line.

[0009] The inlet of the manual stop valve V4 of the exhaust system is connected to the port C on the top of the liquid nitrogen storage tank through a supporting pipeline, and the outlet is connected to the pressure transmitter II. The pressure transmitter II transmits the control signal to the automatic regulating valve V7 through a signal line. The inlet of the automatic regulating valve V7 is connected to the port G on the top of the liquid nitrogen storage tank through a supporting pipeline, and the outlet of the automatic regulating valve V7 is connected to the atmosphere through a supporting pipeline.

[0010] During operation, the liquid nitrogen in the cold box of the distillation tower enters the liquid nitrogen storage tank through the manual stop valve V1 and the supporting pipeline via the liquid nitrogen storage tank port B for storage and standby. When the liquid nitrogen storage tank supplies liquid nitrogen to the outside, the cryogenic liquid pump delivers liquid nitrogen to the user through the supporting pipeline. Due to the large working flow of the cryogenic liquid pump, the liquid nitrogen in the liquid nitrogen storage tank drops rapidly, resulting in a rapid pressure drop in the liquid nitrogen storage tank. At the same time, the pressure transmitter I of the external air supply system and the pressure transmitter II of the self-pressurized air supply system simultaneously detect that the pressure in the liquid nitrogen storage tank drops too fast and reaches the set value. Then, the pressure transmitter I transmits the control signal to the automatic regulating valve V5, and the pressure transmitter II transmits the control signal to the automatic regulating valve V6. When the pressure transmitter II detects that the pressure in the liquid nitrogen storage tank rises too fast and reaches the set value, the pressure transmitter II transmits the control signal to the automatic regulating valve V7.

[0011] For the external air supply system, the manual stop valve V2 and the manual stop valve V3 are normally open valves, and the vaporizer I is always in working state; the automatic regulating valve V5 opens after receiving the control signal from the pressure transmitter I, and the nitrogen vaporized from the vaporizer I quickly enters the liquid nitrogen storage tank through the supporting pipeline, the automatic regulating valve V5, the manual stop valve V2 and the port A on the top of the liquid nitrogen storage tank to replenish the pressure;

[0012] For the self-pressurizing air supply system, the automatic regulating valve V6 opens after receiving the control signal from the pressure transmitter II. The liquid nitrogen in the liquid nitrogen storage tank is vaporized from the bottom port F of the liquid nitrogen storage tank through the supporting pipeline to the vaporizer II, and then the liquid nitrogen storage tank is pressurized from the top port D of the liquid nitrogen storage tank through the supporting pipeline. Because the self-pressurizing air supply system requires vaporization time, the liquid nitrogen in the liquid nitrogen storage tank is vaporized before the liquid nitrogen storage tank is pressurized. Compared with the external air supply system, there is a hysteresis. After the lag time is reached, the self-pressurizing air supply system and the external air supply system simultaneously pressurize the liquid nitrogen storage tank, shortening the adjustment time for the stable pressure of the liquid nitrogen storage tank.

[0013] For the exhaust system, the automatic regulating valve V7 opens after receiving the control signal from the pressure transmitter II, and the nitrogen in the liquid nitrogen storage tank is discharged into the atmosphere from the port G on the top of the liquid nitrogen storage tank through the automatic regulating valve V7 and the supporting pipeline, so that the pressure in the tank is quickly stabilized.

[0014] Furthermore, the vaporizer II includes two vaporizers connected in parallel, which are switched with each other during operation.

[0015] Furthermore, the vaporizer I comprises two vaporizers connected in parallel, which are switched with each other during operation.

[0016] Furthermore, the cryogenic liquid pump includes a plurality of cryogenic liquid pumps connected in parallel, and one or more pumps are selected to start according to the discharge flow rate during operation.

[0017] Furthermore, a breathing valve is provided on the top of the liquid nitrogen storage tank, and the breathing valve is connected to the port H on the top of the liquid nitrogen storage tank. When the pressure in the tank of the liquid nitrogen storage tank reaches a set positive warning threshold, the breathing valve exhales, and when the pressure in the tank of the liquid nitrogen storage tank reaches a set negative warning threshold, the breathing valve inhales.

[0018] The vaporizers I and II in the gas replenishment system for the instantaneous discharge of liquid nitrogen storage tanks with large flow rates of the present invention are both arranged as two parallel vaporizers. This is because frost and ice may form on the surface of the vaporizers during operation, resulting in a deterioration in the heat exchange effect. Switching between the two parallel vaporizers during operation helps maintain a stable heat exchange effect.

[0019] The external air supply system for the large-flow instantaneous discharge liquid nitrogen storage tank air supply system of the present invention vaporizes the liquid nitrogen in the vacuum storage tank and then fills it into the liquid nitrogen storage tank. Compared with the self-pressurizing air supply system, the vaporizer of the external air supply system is always in a working state, and there is no need to wait for the reaction time of the vaporizer of the self-pressurizing air supply system. The system can respond quickly to replenish the tank pressure of the liquid nitrogen storage tank. After the self-pressurizing system starts working, the adjustment time of the tank pressure can be reduced. At the same time, in order to prevent the storage tank from being overpressurized due to excessive air supply, the exhaust system automatically performs overpressure discharge according to the storage tank pressure, and finally achieves a rapid stabilization of the storage tank pressure.

[0020] The gas replenishment system for a liquid nitrogen storage tank with high-flow instantaneous discharge of the present invention cooperates with a self-pressurizing gas replenishment system, an external gas replenishment system, and an exhaust system to ensure that the pressure in the liquid nitrogen storage tank is quickly replenished and kept constant during high-flow instantaneous discharge of the liquid nitrogen storage tank, thereby preventing negative pressure and overpressure phenomena and ensuring the working stability and equipment safety of the liquid nitrogen storage tank system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a schematic structural diagram of the gas replenishment system for the instantaneous discharge of liquid nitrogen from a liquid nitrogen storage tank with a large flow rate according to the present invention.

[0022] In the figure, 1. Liquid nitrogen storage tank; 2. Fractionator cold box; 3. Cryogenic liquid pump; 4. Pressure transmitter II; 5. Vaporizer II; 6. Vaporizer I; 7. Vacuum storage tank; 8. Pressure transmitter I; 9. Breathing valve;

[0023] V1~V4 are the serial numbers of manual stop valves; V5 and V7 are the serial numbers of automatic regulating valves; V6 is the serial number of automatic on / off valve;

[0024] A, B, C, D, G, and H are the serial numbers of the top ports of the liquid nitrogen storage tank; E and F are the serial numbers of the bottom ports of the liquid nitrogen storage tank. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Example

[0026] like Figure 1As shown, the outlet end of the manual stop valve V1 of this embodiment is connected to the top port B of the liquid nitrogen storage tank 1 through a supporting pipeline, and the liquid nitrogen in the fractionation tower cold box 2 enters the liquid nitrogen storage tank 1 for storage through this path; the inlet end of the large-flow cryogenic liquid pump 3 is connected to the bottom port E of the liquid nitrogen storage tank 1 through a supporting pipeline, and the liquid nitrogen in the liquid nitrogen storage tank 1 is delivered to the user through this path; the inlet end of the manual stop valve V4 is connected to the top port C of the liquid nitrogen storage tank 1 through a supporting pipeline, and the outlet end of the manual stop valve V4 is connected to the pressure transmitter II4 through a supporting pipeline. This path is used to detect the pressure in the tank of the liquid nitrogen storage tank 1 in real time. The pressure transmitter II4 transmits the control signal to the automatic switch valve V6 through the signal line to control the automatic switch valve V6 to control the automatic switch valve V6. The valve V6 is opened and closed, the inlet end of the automatic switch valve V6 is connected to the bottom port F of the liquid nitrogen storage tank 1 through a supporting pipeline, the outlet end of the automatic switch valve V6 is connected to the inlet end of the vaporizer Ⅱ5 through a supporting pipeline, and the outlet end of the vaporizer Ⅱ5 is connected to the top port D of the liquid nitrogen storage tank 1 through a supporting pipeline. This path is a self-pressurized air supply system, which can realize the vaporization of the liquid nitrogen in the liquid nitrogen storage tank 1 into nitrogen gas and return it to the liquid nitrogen storage tank 1 to adjust the tank pressure of the liquid nitrogen storage tank 1, and whether the vaporizer Ⅱ5 works or not is controlled by the signal of the pressure transmitter Ⅱ4; the pressure transmitter Ⅱ4 also transmits the control signal to the automatic regulating valve V7 through the signal line to control the opening of the automatic regulating valve V7. The inlet end of the automatic regulating valve V7 is connected to the The inlet of the vaporizer I6 is connected to the bottom port of the vacuum storage tank 7 through a supporting pipeline, and the outlet of the vaporizer I6 is connected to the inlet of the automatic regulating valve V5 through a supporting pipeline. The outlet of the automatic regulating valve V5 is connected to the inlet of the manual stop valve V2 through a supporting pipeline. The outlet of the manual stop valve V2 is connected to the top port A of the liquid nitrogen storage tank 1 through a supporting pipeline. The inlet of the manual stop valve V3 is connected to the outlet of the automatic regulating valve V5 through a supporting pipeline. The outlet of manual shutoff valve V3 is connected to pressure transmitter I8 via a matching pipeline. Pressure transmitter I8 transmits a control signal to automatic regulating valve V5 via a signal line, controlling its opening. This path is an external air supply system, which vaporizes liquid nitrogen from vacuum storage tank 7 and then fills it into liquid nitrogen storage tank 1. The operation of the external air supply system is controlled by a signal from pressure transmitter I8. Compared to the self-pressurizing air supply system, vaporizer I6 is always in operation, eliminating the need to wait for vaporizer II5 to react. This allows for rapid response to replenish the pressure in liquid nitrogen storage tank 1. Once the self-pressurizing system begins operating, the pressure adjustment time is reduced, achieving rapid stabilization. Liquid nitrogen storage tank 1 is also connected to a breathing valve 9 via top port H. Breathing valve 9 automatically activates exhalation and inhalation based on whether the pressure in liquid nitrogen storage tank 1 reaches a set positive or negative value, ensuring the safety of liquid nitrogen storage tank 1.

[0027] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A liquid nitrogen storage tank air replenishment system for instantaneous discharge of large flow rate, wherein a liquid inlet device is provided on the liquid nitrogen storage tank (1), the liquid inlet device comprises a manual stop valve V1 and a matching pipeline, the inlet end of the manual stop valve V1 is connected to the fractionation tower cold box (2), and the outlet end is connected to the top port B of the liquid nitrogen storage tank (1); a liquid discharge device is provided on the liquid nitrogen storage tank (1), the liquid discharge device comprises a cryogenic liquid pump (3) and a matching pipeline, the inlet end of the cryogenic liquid pump (3) is connected to the bottom port E of the liquid nitrogen storage tank (1), and the outlet end is connected to a user; characterized in that The gas supply system for high-flow instantaneous discharge of liquid nitrogen storage tanks includes a self-pressurized gas supply system, an external gas supply system and an exhaust system; The inlet end of the manual stop valve V4 of the self-pressurized air supply system is connected to the top port C of the liquid nitrogen storage tank (1) through a matching pipeline, and the outlet end is connected to the pressure transmitter II (4); the pressure transmitter II (4) transmits the control signal to the automatic switch valve V6 through a signal line, the inlet end of the automatic switch valve V6 is connected to the bottom port F of the liquid nitrogen storage tank (1) through a matching pipeline, the outlet end of the automatic switch valve V6 is connected to the inlet end of the vaporizer II (5) through a matching pipeline, and the outlet end of the vaporizer II (5) is connected to the top port D of the liquid nitrogen storage tank (1) through a matching pipeline; Liquid nitrogen is stored in the vacuum storage tank (7) of the external air supply system. The inlet end of the vaporizer I (6) is connected to the bottom port of the vacuum storage tank (7) through a supporting pipeline, and the outlet end is connected to the inlet end of the automatic regulating valve V5 through a supporting pipeline. The outlet end of the automatic regulating valve V5 is connected to the inlet end of the manual stop valve V2 through a supporting pipeline. The outlet end of the manual stop valve V2 is connected to the top port A of the liquid nitrogen storage tank (1) through a supporting pipeline. The inlet end of the manual stop valve V3 is connected to the outlet pipe of the automatic regulating valve V5 through a supporting pipeline. The outlet end of the manual stop valve V3 is connected to the pressure transmitter I (8) through a supporting pipeline. The pressure transmitter I (8) transmits the control signal to the automatic regulating valve V5 through a signal line. The inlet end of the manual stop valve V4 of the exhaust system is connected to the top port C of the liquid nitrogen storage tank (1) through a matching pipeline, and the outlet end is connected to the pressure transmitter II (4); the pressure transmitter II (4) transmits the control signal to the automatic regulating valve V7 through a signal line, the inlet end of the automatic regulating valve V7 is connected to the top port G of the liquid nitrogen storage tank (1) through a matching pipeline, and the outlet end of the automatic regulating valve V7 is connected to the atmosphere through a matching pipeline; During operation, the liquid nitrogen in the fractionating tower cold box (2) enters the liquid nitrogen storage tank (1) through the manual stop valve V1 and the supporting pipeline via the port B of the liquid nitrogen storage tank (1) for storage of liquid nitrogen for standby use; when the liquid nitrogen storage tank (1) supplies liquid nitrogen to the outside, the cryogenic liquid pump (3) delivers liquid nitrogen to the user through the supporting pipeline. Due to the large working flow of the cryogenic liquid pump (3), the liquid nitrogen in the liquid nitrogen storage tank (1) drops rapidly, resulting in the pressure of the liquid nitrogen storage tank (1) dropping too fast; at the same time, the pressure transmitter of the external air supply system When the pressure transmitter I (8) and the pressure transmitter II (4) of the self-pressurized air supply system simultaneously detect that the pressure in the liquid nitrogen storage tank (1) drops too fast and reaches the set value, the pressure transmitter I (8) transmits the control signal to the automatic regulating valve V5, and the pressure transmitter II (4) transmits the control signal to the automatic switch valve V6. When the pressure transmitter II (4) detects that the pressure in the liquid nitrogen storage tank (1) rises too fast and reaches the set value, the pressure transmitter II (4) transmits the control signal to the automatic regulating valve V7. For the external air supply system, the manual stop valve V2 and the manual stop valve V3 are normally open valves, and the vaporizer I (6) is always in working state; the automatic regulating valve V5 opens after receiving the control signal from the pressure transmitter I (8), and the nitrogen vaporized from the vaporizer I (6) quickly enters the liquid nitrogen storage tank (1) through the supporting pipeline, the automatic regulating valve V5, the manual stop valve V2 and the top port A of the liquid nitrogen storage tank (1) to replenish the pressure; For the self-pressurizing air supply system, the automatic switch valve V6 opens after receiving the control signal of the pressure transmitter II (4), and the liquid nitrogen in the liquid nitrogen storage tank (1) is vaporized from the bottom port F of the liquid nitrogen storage tank (1) through the supporting pipeline to the vaporizer II (5), and then the liquid nitrogen storage tank (1) is pressurized from the top port D of the liquid nitrogen storage tank (1) through the supporting pipeline; because the self-pressurizing air supply system requires vaporization time, the liquid nitrogen in the liquid nitrogen storage tank (1) is vaporized before the liquid nitrogen storage tank (1) is pressurized, which has a lag compared with the external air supply system. After the lag time is reached, the self-pressurizing air supply system and the external air supply system simultaneously pressurize the liquid nitrogen storage tank (1), thereby shortening the adjustment time of the pressure stabilization of the liquid nitrogen storage tank (1); For the exhaust system, the automatic regulating valve V7 opens after receiving the control signal from the pressure transmitter II (4), and the nitrogen in the liquid nitrogen storage tank (1) is discharged into the atmosphere from the top port G of the liquid nitrogen storage tank (1) through the automatic regulating valve V7 and the supporting pipeline, so that the pressure in the tank is quickly stabilized.

2. The gas replenishment system for large-flow instantaneous discharge of liquid nitrogen storage tank according to claim 1 is characterized in that: The vaporizer II (5) comprises two vaporizers connected in parallel, which are switched with each other during operation.

3. The gas replenishment system for large-flow instantaneous discharge of liquid nitrogen storage tank according to claim 1 is characterized in that: The vaporizer I (6) comprises two vaporizers connected in parallel, which are switched with each other during operation.

4. The gas replenishment system for large-flow instantaneous discharge of liquid nitrogen storage tank according to claim 1 is characterized in that: The cryogenic liquid pump (3) comprises a plurality of cryogenic liquid pumps (3) connected in parallel, and one or more pumps are selected to start according to the discharge flow rate during operation.

5. The gas replenishment system for large-flow instantaneous discharge of liquid nitrogen storage tank according to claim 1 is characterized in that: A breathing valve (9) is provided on the top of the liquid nitrogen storage tank (1), and the breathing valve (9) is communicated with a port H on the top of the liquid nitrogen storage tank (1). When the pressure in the tank of the liquid nitrogen storage tank (1) reaches a set positive warning threshold, the breathing valve (9) exhales, and when the pressure in the tank of the liquid nitrogen storage tank (1) reaches a set negative warning threshold, the breathing valve (9) inhales.

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