Cold energy recovery system for emptying low-temperature nitrogen of normal-pressure liquid nitrogen storage tank

Abstract

The utility model discloses an atmospheric pressure liquid nitrogen storage tank emptying low-temperature nitrogen cooling capacity recovery system, which relates to the technical field of deep cooling and comprises a liquid nitrogen storage tank, a standby regulating valve on the liquid nitrogen storage tank is connected with a low-temperature supercharger through a pipeline, and the outlet end of the low-temperature supercharger is connected with a vacuum heat preservation pipeline. The outlet end of the vacuum heat preservation pipeline is connected with an emptying pipeline and a conveying pipeline used for being connected with a nitrogen pipeline in an air separation device, and the output end of the nitrogen pipeline is further connected with a heat exchanger. The supercharged low-temperature nitrogen is conveyed to a nitrogen pipeline in the air separation device through a vacuum heat preservation pipeline and a conveying pipeline, so that the supercharged low-temperature nitrogen is converged with nitrogen produced by the air separation device, then enters the heat exchanger, is subjected to heat exchange with positive flow air in the heat exchanger, is reheated and then is discharged out of the cold box, and therefore the purpose of recycling cold energy is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to low temperature liquefaction technical field, specifically, relate to a kind of normal-pressure liquid nitrogen storage tank emptying low-temperature nitrogen cold recovery system. BACKGROUND

[0002] The gas phase working pressure of normal-pressure liquid nitrogen storage tank is usually controlled at about 15KPa, and the pressure of evaporated low-temperature (-195.8℃) nitrogen is low, and the pressure of nitrogen pipeline in air separation device is about 40KPa, so that the low-temperature nitrogen evaporated from liquid nitrogen storage tank cannot be directly sent into nitrogen pipeline in air separation device for mixing, and with the continuous construction of project, more and more large normal-pressure low-temperature liquid storage tanks are built, and since the liquid nitrogen produced by air separation and liquefaction device has no supercooling degree, there is natural evaporation of 3%-7% in the process of liquid inlet, storage and filling, and for a long time, the air separation industry has not found an efficient utilization method, and there is great loss of cold and nitrogen. SUMMARY

[0003] The utility model discloses a kind of normal-pressure liquid nitrogen storage tank emptying low-temperature nitrogen cold recovery system, can effectively recover the cold and nitrogen of emptying, avoid waste to cold, greatly save enterprise cost.

[0004] To achieve the purpose of the utility model, the technical scheme adopted is: a normal-pressure liquid nitrogen storage tank emptying low-temperature nitrogen cold recovery system, comprising a liquid nitrogen storage tank, a standby regulating valve on the liquid nitrogen storage tank is connected with a low-temperature booster by a pipeline, an outlet end of the low-temperature booster is connected with a vacuum insulation pipeline, a discharge pipeline and a conveying pipeline for connecting with a nitrogen pipeline in air separation device are connected to the outlet end of the vacuum insulation pipeline, and the output end of the nitrogen pipeline is further connected with a heat exchanger.

[0005] Further, it further includes liquid nitrogen gasification standby system storage tank, vaporizer, piston nitrogen compressor connected in sequence, and parallel pipeline is further connected between the vaporizer inlet and the vacuum insulation pipeline;The outlet of the vaporizer is further connected with a gasification pipeline, and the inlet of the piston nitrogen compressor is provided with a low-pressure nitrogen pipeline connected with the heat exchanger;The outlet of the piston nitrogen compressor is further provided with a gas supply pipeline one for connecting with gas supply equipment, and the outlet end of the gasification pipeline is connected in parallel on the gas supply pipeline one.

[0006] Further, the outlet of the piston nitrogen compressor is further provided with a gas supply pipeline two for connecting with liquefaction device or filling system.

[0007] Further, the outlet pressure of the low-temperature booster is 45KPa-55KPa.

[0008] Further, an adjusting valve is further installed between the low-temperature booster and the standby regulating valve on the liquid nitrogen storage tank.

[0009] Further, the low-pressure check valve is installed between the low-temperature supercharger and the standby regulating valve on the liquid nitrogen storage tank, and the low-pressure check valve is connected with the low-temperature supercharger.

[0010] Further, the emergency cut-off valve is installed at the inlet end of the conveying pipeline, and the emergency cut-off valve is connected with the low-temperature supercharger.

[0011] Further, the online micro-oxygen analyzer is installed on the pipeline between the liquid nitrogen storage tank and the low-temperature supercharger, and the online micro-oxygen analyzer is connected with the emergency cut-off valve.

[0012] Further, the low-pressure check valve is installed on the pipeline between the liquid nitrogen storage tank and the low-temperature supercharger.

[0013] Further, the sealing gas of the low-temperature supercharger is high-purity nitrogen.

[0014] The beneficial effects of the present application are as follows:

[0015] The present application pressurizes the low-temperature nitrogen gas discharged from the normal-pressure liquid nitrogen storage tank, so that the pressurized gas can be mixed in the nitrogen pipeline in the air separation device, and after mixing, the gas is sent into the heat exchanger for reheat use or after reheat, the gas is sent into the piston nitrogen compressor for use, thereby effectively recovering the vented cold energy and nitrogen, avoiding waste of the cold energy, and greatly saving the enterprise cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings illustrate exemplary embodiments of the present application and, together with the general description of the application given above, and the detailed description of the embodiments given below, serve to explain the principles of the present application. These drawings are included herewith to provide further understanding of the present application and are incorporated in and constitute a part of this specification.

[0017] Figure 1 is a flow chart of the normal-pressure liquid nitrogen storage tank venting low-temperature nitrogen gas cold energy recovery system provided by the present application.

[0018] Markings in the drawings and corresponding component names:

[0019] 1, liquid nitrogen storage tank, 2, low-temperature supercharger, 3, vacuum heat preservation pipeline, 4, conveying pipeline, 5, liquid nitrogen gasification standby system storage tank, 6, vaporizer, 7, piston nitrogen compressor, 8, parallel pipeline, 9, gasification pipeline, 10, low-pressure nitrogen pipeline, 11, gas supply pipeline I, 12, gas supply pipeline II, 13, venting pipeline, 14, air separation device, 15, nitrogen pipeline, 16, heat exchanger. DETAILED DESCRIPTION

[0020] The utility model will be made further detailed explanation below combining with the drawings and implementation. It can be understood that the specific implementation described here is only used for explaining relevant content, and is not limited to the utility model. In addition, it needs to be explained that only the part related to the utility model is shown in the drawings for the convenience of description.

[0021] It needs to be explained that the implementation in the utility model and the features in the implementation can be combined with each other without conflict. The utility model will be explained in detail below with reference to the drawings and in combination with the implementation.

[0022] As Figure 1 The utility model provides a kind of normal-pressure liquid nitrogen storage tank emptying low-temperature nitrogen gas cold quantity recovery system, including the liquid nitrogen for storing liquid nitrogen storage tank 1, the spare regulating valve and emptying valve are provided on the liquid nitrogen storage tank 1, wherein, emptying valve is used to ensure the safety of liquid nitrogen storage tank 1, and the spare regulating valve on the liquid nitrogen storage tank 1 is connected with cryogenic booster 2 by pipeline, and cryogenic booster 2 pressurizes nitrogen gas led out by the spare regulating valve on the liquid nitrogen storage tank 1, and the outlet end of cryogenic booster 2 is connected with vacuum insulation pipeline 3, vacuum insulation pipeline 3 can adopt the heat preservation mode of current vacuum pipe or stainless steel bare pipe, aluminum pipe, and the outlet end of vacuum insulation pipeline 3 is connected with emptying pipeline 13 respectively, conveying pipeline 4 for being connected with nitrogen gas pipeline 15 in air separation device 14, and the output end of nitrogen gas pipeline 15 is also connected with heat exchanger 16, so that nitrogen gas after pressurization by cryogenic booster 2 can be sent into nitrogen gas pipeline 15 in air separation device 14, is combined with the nitrogen gas generated by air separation device 14, and after mixing, it is sent into heat exchanger 16 and exchanges heat with the normal flow air in heat exchanger 16, and after reheating, it is exported from cold box, so as to achieve the purpose of recovering cold quantity and nitrogen gas.

[0023] The utility model also includes that liquid nitrogen gasification backup system storage tank 5, vaporizer 6, piston nitrogen compressor 7 are connected in sequence, wherein vaporizer 6 is air bath type vaporizer, and vaporizer 6 is used to reheat nitrogen gas after pressurization by cryogenic booster 2, and piston nitrogen compressor 7 is used to compress the nitrogen gas after reheating, to meet the use of user;Parallel pipeline 8 is also connected between vaporizer 6 import and vacuum insulation pipeline 3, so that nitrogen gas after pressurization by cryogenic booster 2 can be sent into vaporizer 6 and reheat, and the nitrogen gas after reheating can be sent into piston nitrogen compressor 7 and compress, simultaneously, the inlet of piston nitrogen compressor 7 is equipped with low-pressure nitrogen gas pipeline 10 connected with heat exchanger 16, so that nitrogen gas after pressurization by cryogenic booster 2 can be sent into nitrogen gas pipeline 15 of air separation device 14, is combined with the nitrogen gas generated by air separation device 14, and after mixing, it is sent into heat exchanger 16 and exchanges heat with the normal flow air in heat exchanger 16, so that nitrogen gas after reheat by heat exchanger 16 can be sent into piston nitrogen compressor 7 and compress.

[0024] The outlet of the vaporizer 6 is also connected with a gasification pipeline 9, and the outlet of the piston nitrogen compressor 7 is also provided with a gas supply pipeline I 11 for connecting with a gas supply device; the outlet end of the gasification pipeline 9 is connected in parallel with the gas supply pipeline I 11, so that the nitrogen gas reheated by the vaporizer 6 can be partly introduced into the piston nitrogen compressor 7 for compression, and the other part of the nitrogen gas reheated by the vaporizer 6 can be sent into the gas supply pipeline I 11 through the gasification pipeline 9 to be mixed with the nitrogen gas compressed by the piston nitrogen compressor 7, and finally supplied to users through the gas supply pipeline I 11; at the same time, the nitrogen gas pressurized by the low-temperature booster 2 is sent into the nitrogen pipeline 15 of the air separation device 14 for mixing, and after being reheated by the heat exchanger 16, is sent into the piston nitrogen compressor 7 for compression, and the other part of the nitrogen gas reheated by the vaporizer 6 can be sent into the gas supply pipeline I 11 through the gasification pipeline 9 to be mixed with the nitrogen gas compressed by the piston nitrogen compressor 7, and finally also supplied to users through the gas supply pipeline I 11, so that the cold energy is recycled and used.

[0025] The outlet of the piston nitrogen compressor 7 in the recycling system is also provided with a gas supply pipeline II 12 for connecting with a liquefaction device or a filling system, so that the nitrogen gas reheated by the vaporizer 6 can be sent into the gas supply pipeline I 11 through the gasification pipeline 9 to be mixed with the nitrogen gas compressed by the piston nitrogen compressor 7, and then directly supplied to the liquefaction device or the filling system through the gas supply pipeline, so as to meet the use requirement of users.

[0026] In the utility model, the outlet pressure of the low-temperature booster 2 is 45KPa-55KPa. Since the gas phase working pressure of the liquid nitrogen storage tank 1 is usually controlled at about 15KPa, in order to ensure that the gas phase in the liquid nitrogen storage tank 1 can enter into the nitrogen pipeline 15 in the air separation device 14 to be mixed with the nitrogen gas generated thereby, the low-temperature booster 2 can pressurize the nitrogen gas at about 15KPa to 45KPa-55KPa, so that the gas phase of the liquid nitrogen storage tank 1 has sufficient pressure to enter into the nitrogen pipeline 15 in the air separation device 14, and after being mixed with the nitrogen gas generated by the air separation device 14, enters into the heat exchanger 16. The outlet pressure of the low-temperature booster 2 is 50KPa; the outlet pressure of the piston nitrogen compressor 7 is 0.65MPa.

[0027] In order to prevent the pressure of the liquid nitrogen storage tank 1 from being reduced to negative pressure under the suction of the low-temperature booster 2, an adjusting valve is installed before the low-temperature booster 2 for automatically adjusting the pressure of the liquid nitrogen storage tank 1; specifically, the adjusting valve is opened wide when the pressure of the liquid nitrogen storage tank 1 is increased, and is closed narrow when the pressure of the liquid nitrogen storage tank 1 is decreased.

[0028] To prevent the overpressure caused by the nitrogen gas with a pressure of about 40 KPa in the air separation device 14 flowing back to the liquid nitrogen storage tank 1 through the pipeline when the low-temperature booster 2 suddenly stops during operation, an emergency shut-off valve is installed at the inlet end of the delivery pipeline 4, and a low-pressure check valve is installed between the low-temperature booster 2 and the standby regulating valve on the liquid nitrogen storage tank 1; at the same time, the low-pressure check valve and the emergency shut-off valve are connected with the low-temperature booster 2 in linkage, so that when the low-temperature booster 2 stops, the low-pressure check valve and the emergency shut-off valve are closed in linkage.

[0029] To prevent the air from flowing into the pipeline in the present recycling system and causing pollution, the high-purity nitrogen gas is used as the sealing gas for the low-temperature booster 2; at the same time, the online micro-oxygen analyzer is installed on the pipeline between the liquid nitrogen storage tank 1 and the low-temperature booster 2, the online micro-oxygen analyzer detects the oxygen content in the pipeline in real time, and the alarm is given when the oxygen content is detected to be over the standard; at the same time, the online micro-oxygen analyzer is connected with the low-pressure check valve, the emergency shut-off valve and the low-temperature booster 2 in linkage, when the online micro-oxygen analyzer detects that the oxygen content is over the standard, the low-pressure check valve and the emergency shut-off valve are closed, and the low-temperature booster 2 is stopped.

[0030] When the present recycling system works:

[0031] Working mode one: the nitrogen gas in the liquid nitrogen storage tank 1 is pressurized by the low-temperature booster 2 and then sent into the nitrogen gas pipeline 15 of the air separation device 14 through the delivery pipeline 4, mixed with the nitrogen gas generated by the air separation device 14, and then sent into the heat exchanger 16 to exchange heat with the normal-flow air in the heat exchanger 16, and finally compressed to 0.65 MPa in the piston nitrogen compressor 7 and then delivered to the user through the gas supply pipeline one 11.

[0032] Working mode two: the nitrogen gas in the liquid nitrogen storage tank 1 is pressurized by the low-temperature booster 2 and then sent into the vaporizer 6 through the parallel pipeline 8 to be reheated, the reheated nitrogen gas is sent into the piston nitrogen compressor 7 to be compressed to 0.65 MPa, and then delivered to the user through the gas supply pipeline one 11.

[0033] In the description of the present application, the description of the terms "one embodiment / way", "some embodiments / ways", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment / way or example are contained in at least one embodiment / way or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. Furthermore, the different embodiments / ways or examples described in the present application and the features of the different embodiments / ways or examples can be combined and combined by those skilled in the art without contradiction.

[0034] Furthermore, the terms "first", "second", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an ordered ranking of the indicated technical features. Thus, a feature defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example two, three, etc., unless otherwise explicitly and specifically limited.

[0035] Those skilled in the art should understand that the above embodiments are only for clearly illustrating the present application, and are not intended to limit the scope of the present application. Based on the above disclosure, other changes or modifications can also be made by those skilled in the art, and these changes or modifications are still within the scope of the present application.

Claims

1. A cryogenic nitrogen cooling capacity recovery system for venting liquid nitrogen storage tanks at atmospheric pressure, characterized in that, It comprises a liquid nitrogen tank (1), a standby regulating valve on the liquid nitrogen tank (1) is connected with a low-temperature booster (2) through a pipeline, an outlet end of the low-temperature booster (2) is connected with a vacuum insulation pipeline (3), a venting pipeline (13) and a delivery pipeline (4) for connecting with a nitrogen pipeline (15) in an air separation device are connected to an outlet end of the vacuum insulation pipeline (3), and an outlet end of the nitrogen pipeline (15) is further connected with a heat exchanger (16).

2. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold-quantity recovery system according to claim 1, characterized in that, It further comprises a liquid nitrogen gasification backup system tank (5), a vaporizer (6) and a piston nitrogen compressor (7) connected in sequence, and a parallel pipeline (8) is further connected between the vaporizer (6) inlet and the vacuum insulation pipeline (3); the vaporizer (6) outlet is further connected with a gasification pipeline (9), and the piston nitrogen compressor (7) inlet is provided with a low-pressure nitrogen pipeline (10) connected with the heat exchanger (16); the piston nitrogen compressor (7) outlet is further provided with a gas supply pipeline I (11) for connecting with a gas supply device, and an outlet end of the gasification pipeline (9) is connected in parallel with the gas supply pipeline I (11).

3. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold-quantity recovery system according to claim 2, characterized in that, The piston nitrogen compressor (7) outlet is further provided with a gas supply pipeline II (12) for connecting with a liquefaction device or a filling system.

4. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold energy recovery system according to claim 2 or 3, characterized in that, The outlet pressure of the low-temperature booster (2) is 45KPa-55KPa.

5. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold energy recovery system according to claim 2 or 3, characterized in that, A regulating valve is further installed between the low-temperature booster (2) and the standby regulating valve on the liquid nitrogen tank (1).

6. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold energy recovery system according to claim 2 or 3, characterized in that, A low-pressure check valve is further installed between the low-temperature booster (2) and the standby regulating valve on the liquid nitrogen tank (1), and the low-pressure check valve is connected with the low-temperature booster (2) in linkage.

7. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold-quantity recovery system according to claim 6, characterized in that, An emergency shut-off valve is installed at an inlet end of the delivery pipeline (4), and the emergency shut-off valve is connected with the low-temperature booster (2) in linkage.

8. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold-quantity recovery system according to claim 7, characterized in that, An online trace oxygen analyzer is further installed on a pipeline between the liquid nitrogen tank (1) and the low-temperature booster (2), and the online trace oxygen analyzer is connected with the emergency shut-off valve in linkage.

9. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold-quantity recovery system according to claim 6, characterized in that, A low-pressure check valve is further installed on a pipeline between the liquid nitrogen tank (1) and the low-temperature booster (2).

10. The atmospheric liquid nitrogen tank venting cryogenic nitrogen cold energy recovery system according to claim 2 or 3, characterized in that, The sealing gas of the low-temperature booster (2) is high-purity nitrogen.

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