A vacuum degree early warning alarm method for liquid hydrogen transportation equipment

Abstract

The present invention relates to a vacuum degree early warning alarm method, and in particular to a vacuum degree early warning alarm method for liquid hydrogen transportation equipment. First, a correlation model between the pressure in the tank and the storage and transportation time under different interlayer vacuum degrees is constructed; the current pressure change value in the tank is obtained; finally, the obtained pressure change value in the tank is input into the correlation model to obtain the vacuum degree that is about to exceed the safety threshold range, and issue an early warning at the same time; or obtain the vacuum degree that exceeds the safety threshold range, and alarm the transportation system that exceeds the safety threshold. The present invention has the characteristics of convenient monitoring, high sensitivity and good effect, and by adopting such a vacuum early warning method, the vacuum degree change of the insulation layer can be detected in real time to ensure a good insulation effect, greatly reducing the risk of vacuum failure during the liquid hydrogen transportation process.

Description

Technical Field

[0001] The invention relates to a vacuum degree early warning alarm method, in particular to a vacuum degree early warning alarm method for liquid hydrogen transportation equipment. Background Art

[0002] Hydrogen energy is recognized as the most promising clean energy in the 21st century. With the development of hydrogen energy applications, the development of the liquid hydrogen storage and transportation equipment market has been stimulated accordingly. Liquid hydrogen transportation has the advantages of economy, high efficiency, and higher safety. Since the transportation temperature of liquid hydrogen needs to be kept below -253°C, which has a large temperature difference with the external environment, in order to achieve the safe operation of liquid hydrogen transportation equipment and the longest possible storage and transportation time, liquid hydrogen transportation equipment adopts high-vacuum multi-layer insulation material technology. However, the performance of multi-layer insulation materials is greatly affected by the vacuum degree in the interlayer of the mobile equipment. When the vacuum degree in the insulation interlayer deteriorates, the heat conductivity of the residual gas will account for a large proportion of the total heat leakage, and its insulation performance will also decrease accordingly. Therefore, it is necessary to monitor the vacuum degree of liquid hydrogen transportation equipment for early warning and alarm.

[0003] For the vacuum degree monitoring of liquid hydrogen transportation equipment, the existing monitoring technology basically uses vacuum gauges for monitoring. However, vacuum gauges are expensive and easily damaged during the transportation of equipment, making monitoring difficult. It is necessary to find other convenient ways to characterize the vacuum degree in the transportation equipment. Summary of the invention

[0004] The present invention aims to find a vacuum degree early warning alarm method and system for liquid hydrogen transportation equipment, which solves the problem of difficulty in vacuum degree monitoring of liquid hydrogen transportation equipment in the prior art.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0006] A vacuum degree early warning alarm method for liquid hydrogen transportation equipment, characterized in that it includes

[0007] Construct a correlation model between tank pressure and storage and transportation time under different interlayer vacuum degrees;

[0008] Get the current pressure change value in the tank;

[0009] The obtained pressure change value inside the tank is input into the correlation model to obtain the vacuum degree that is about to exceed the safety threshold range, and issue an early warning at the same time; or the vacuum degree that exceeds the safety threshold range is obtained, and an alarm is issued for the transportation system that exceeds the safety threshold.

[0010] In the above-mentioned vacuum warning alarm method for liquid hydrogen transportation equipment, the construction of the correlation model includes the following steps:

[0011] The liquid hydrogen transport equipment is filled with a set amount of liquid hydrogen medium, and the vacuum level of the interlayer is evacuated to 10-4Pa, 10-3Pa, 10-2Pa, 10-1Pa, 1Pa, and 10Pa for testing.

[0012] The pressure value in the tank is obtained at set intervals, the pressure-time curve under different vacuum degrees is plotted, and a pressure change model is constructed.

[0013] In the above-mentioned vacuum warning alarm method for liquid hydrogen transportation equipment, the safety threshold is set based on the following definition:

[0014] Setting 10 -1 Pa is the system warning value; 1Pa is set as the system alarm value; and the pressure change is divided into three areas by the vacuum safety threshold, namely, vacuum <10 -1 Pa area, 10 -1 Pa<vacuum degree<1Pa, vacuum degree>1Pa.

[0015] In the above-mentioned vacuum warning alarm method for liquid hydrogen transportation equipment, the specific steps of the warning include:

[0016] Obtain the i point, j point and pressure value for a period of time during the operation of the liquid hydrogen transportation equipment, and input the pressure value into the pressure change model, where i = j-1 and the unit is

[0017] If the pressure changes corresponding to point i and point j are within the same area, the vacuum degree of the system interlayer is determined. - 1 In the vacuum range of Pa~1Pa, the system will give an early warning. If it is above 1Pa, the system will give an alarm.

[0018] If the pressure changes corresponding to point i and point j are in different ranges, continue to obtain point j+n (n=1, 2, 3) in a short period of time until the pressure changes within this period are in the same range, and determine the system vacuum degree according to the above method.

[0019] In the above-mentioned vacuum warning alarm method for liquid hydrogen transportation equipment, the following definitions are based on the same area:

[0020] If point i and point j are both in the area between any two curves of the pressure change model, they are judged to belong to the same area.

[0021] Therefore, the present invention has the following advantages: it has the characteristics of convenient monitoring, high sensitivity and good effect, and by adopting such a vacuum early warning method, the vacuum degree change of the insulation layer can be detected in real time to ensure a good insulation effect, thereby greatly reducing the risk of vacuum failure in the liquid hydrogen transportation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 It is a schematic diagram of the system structure required by the present invention.

[0023] Attached Figure 2 It is a schematic diagram of the pressure change model (pressure change curve in the tank under the same vacuum degree) constructed in the embodiment of the present invention.

[0024] Attached Figure 3 It is a schematic diagram of point i and point j in the same area in an embodiment of the present invention.

[0025] Attached Figure 4 It is a schematic diagram of an embodiment of the present invention in which point i and point j are not in the same area. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0027] Example:

[0028] As shown in the attached figure, the liquid hydrogen transportation equipment consists of 1-inner container, 2-insulating material, 3-outer shell, 4-pressure gauge, 5-remote monitoring system, and 6-safety release device, among which:

[0029] The inner container is a pressure vessel that contains liquid hydrogen medium and is made of stainless steel. The multi-layer insulation material is composed of alternating layers of radiation screens with high reflectivity and spacers with low thermal conductivity, which are coated on the outer surface of the inner container 1 to play a role in insulation. The outer shell is supported and connected to the inner container 1 by a supporting structure. The sealed space formed by the inner container 1 and the outer shell 3 is the interlayer space. The insulation performance of the insulation material 2 is proportional to the vacuum degree of the interlayer space. The higher the vacuum degree, the better the insulation performance of the insulation material. Existing studies have shown that when the vacuum degree is 10 -2 Pa, the insulation material has excellent insulation performance. In the pressure range of 0.01Pa-10Pa, the apparent thermal conductivity increases linearly with pressure, the residual gas heat conduction accounts for a large proportion of the total heat leakage, and the insulation performance is greatly reduced.

[0030] The pressure gauge is used to monitor the internal pressure value of liquid hydrogen equipment in real time.

[0031] The remote monitoring system sends the data of the pressure gauge to the remote monitoring system at regular intervals, monitors the vacuum degree of the mezzanine space through pressure changes over a period of time, determines whether the vacuum degree exceeds the preset safety threshold range, and alarms the system that exceeds the threshold.

[0032] Since liquid hydrogen is flammable and explosive, a safety relief device is set to ensure the safety of the liquid hydrogen equipment system under extreme working conditions. The correlation model between the tank pressure and the storage and transportation time under different interlayer vacuum degrees is shown in the attached Figure 2 .

[0033] The curves in the above data model are respectively -4 Pa, 10 -3 Pa, 10 -2 Pa, 10 -1 The correlation curve between the pressure inside the tank and the storage and transportation time at Pa, 1Pa, and 10Pa.

[0034] When the system determines that the vacuum degree of the interlayer is 10 -1 When the vacuum degree is within the range of Pa~1Pa, the system will issue an alarm.

[0035] When the system determines that the vacuum degree of the interlayer is >1Pa, the system will alarm.

[0036] The model of the present invention is simplified as follows:

[0037] The liquid hydrogen transport equipment is filled with a certain amount of liquid hydrogen medium, and the vacuum level of the interlayer is 10 -4 Pa, 10 -3 Pa, 10 -2 Pa, 10 -1 Pa, 1Pa, and 10Pa were tested. The pressure value in the tank was obtained at regular intervals. The pressure-time curves under different vacuum degrees were plotted to construct a pressure change model. The schematic diagram is shown above. According to existing research, when the vacuum degree is higher than 10 -1 Pa, the performance of the insulation material begins to decrease significantly. Set 10 -1 Pa is the system warning value; when the vacuum degree is higher than 1Pa, the performance of the insulation material is greatly reduced, and 1Pa is set as the system alarm value. The pressure change is divided into three areas by the vacuum safety threshold, namely, vacuum degree <10 -1 Pa area, 10 -1 Pa<vacuum degree<1Pa, vacuum degree>1Pa.

[0038] Obtain the i and j points during a period of time during the operation of the liquid hydrogen transportation equipment and input them into the above pressure change model.

[0039] If the pressure changes corresponding to point i and point j are in the same area, the vacuum degree of the system interlayer is determined. -1 In the vacuum range of Pa~1Pa, the system will give an early warning. If it is above 1Pa, the system will give an alarm.

[0040] If the pressure changes corresponding to point i and point j are in different ranges, continue to obtain point j+n (n=1, 2, 3) in a short period of time until the pressure changes within this period are in the same range, and determine the system vacuum degree according to the above method.

[0041] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A vacuum warning alarm method for liquid hydrogen transportation equipment, characterized in that: include Construct a correlation model between tank pressure and storage and transportation time under different interlayer vacuum degrees; Get the current pressure change value in the tank; The obtained pressure change value inside the tank is input into the correlation model to obtain the vacuum degree that is about to exceed the safety threshold range, and an early warning is issued at the same time; Or obtain the vacuum degree that exceeds the safety threshold range, and alarm the transportation system that exceeds the safety threshold; The construction of the association model includes the following steps: The liquid hydrogen transport equipment is filled with a set amount of liquid hydrogen medium, and the vacuum level of the interlayer is 10 -4 Pa, 10 - 3 Pa, 10 -2 Pa, 10 -1 Pa, 1Pa, 10Pa for testing; Obtain the pressure value in the tank at set intervals, draw pressure-time curves under different vacuum degrees, and build a pressure change model; The safety threshold is set based on the following definitions: Setting 10 -1 Pa is the system warning value; 1Pa is set as the system alarm value; and the pressure change is divided into three areas by the vacuum safety threshold, namely, vacuum <10 -1 Pa area, 10 -1 Pa<vacuum degree<1Pa and vacuum degree>1Pa; The specific steps of early warning include: Obtaining point i and point j during a period of time during the operation of the liquid hydrogen transport equipment, and inputting them into the above pressure change model, where i=j-1, and the unit is hour; If the pressure changes corresponding to point i and point j are within the same area, the vacuum degree of the system interlayer is determined. -1 In the vacuum range of Pa~1Pa, the system will give an early warning. If it is above 1Pa, the system will give an alarm. If the pressure changes corresponding to point i and point j are in different regions, continue to obtain point j+n in a short period of time, where n is a positive integer in hours, until the pressure changes in this period of time are in the same region, and judge the system vacuum degree according to the above method; The same region is defined as follows: If point i and point j are both in the area between two adjacent curves of the pressure change model, they are judged to belong to the same area.

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