CN108918024A - One kind is with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method - Google Patents
One kind is with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method Download PDFInfo
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- CN108918024A CN108918024A CN201810883745.5A CN201810883745A CN108918024A CN 108918024 A CN108918024 A CN 108918024A CN 201810883745 A CN201810883745 A CN 201810883745A CN 108918024 A CN108918024 A CN 108918024A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L21/00—Vacuum gauges
- G01L21/10—Vacuum gauges by measuring variations in the heat conductivity of the medium, the pressure of which is to be measured
- G01L21/14—Vacuum gauges by measuring variations in the heat conductivity of the medium, the pressure of which is to be measured using thermocouples
Abstract
The present invention discloses a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, and step is：（1）Residual dielectric in LNG gas cylinder is excluded completely, opening gas cylinder valve makes internal and external temperature without significant change.（2）Measurement point one is taken respectively in bottle mouth of gas cylinder, middle part and tail position, and thermocouple and signal transmitting device are installed；（3）LNG medium is filled into gas cylinder, while to 3 continuously measuring temperatures, LNG closes imported valve after the completion of filling.The data continuously measured should be sent to data processing platform (DPP) in real time, and be depicted as the measured curve changed over time；（4）Measured curve and the assessment curve under qualified vacuum degree condition are compared, if measured curve is with assessment curve co-insides or above assessment curve, gas cylinder vacuum degree verifies as qualification, shows that current vacuum level can be effectively insulated；Otherwise, then gas cylinder vacuum degree verify as it is unqualified.This method can greatly shorten Check-Out Time, reduce cost, improve efficiency.
Description
Technical field
The present invention relates to low temperature cylinder vacuum degree measurements, more particularly to one kind quickly to be examined with low-temperature gas cylinder sandwich layer vacuum degree
Survey method.
Background technique
With the fast development of global economy, countries in the world are growing day by day to the consumption of the energy, traditional energy include petroleum,
Coal etc. largely burn, caused by environmental problem become increasingly conspicuous.In order to cope with the Heavy environmental pollution that traditional energy consumption generates
Problem, countries in the world all actively promoting new energy transition, develop and utilize clean energy resource be from now on each national development must
Right trend.LNG is as a kind of efficient, clean energy, the carbon dioxide discharged after burning fewer than petroleum 25%, environment protection significance weight
Greatly.Furthermore LNG has very high volume compression ratio, can make up deficiency of the natural gas in terms of storage and transport, whether use
It is very convenient that vehicle-mounted transport still passes through large-scale transoceanic ship transport.LNG automobile has good as novel environment friendly vehicle at present
Good development prospect, with the LNG mounted gas cylinder that vehicle is installed be widely used to car, car, minibus, mini-bus, city bus,
Engineering truck, heavy truck etc..
Vehicle-mounted LNG gas cylinder is a kind of special container of storage and transportation cryogenic liquid, once container occur failure will cause it is biggish
Economic asset loss, seriously threatens the life security of the people.In order to improve the safety of LNG gas cylinder, gas cylinder is carried out reasonable
It examines very necessary.National standard is not yet put into effect in the periodic inspection of LNG gas cylinder at present, and local mark has been put into effect in only drug in some provinces
Standard, such as Jiangsu Province provincial standard DB32/2037-2012,《Cryogenic insulated cylinder periodic inspection requirement》.LNG is specified in standard
Inside and outside inspection, vacuum degree measurement, safety attachment verification, pipe valve inspection, attachment inspection should be carried out when gas cylinder periodic inspection
It looks into and air-tight test.Wherein the vacuum measurement in inside and outside interlayer is to examine the maximum difficult point of work.Since LNG gas cylinder does not have
The vacuum gauge of direct measurement of vacuum, therefore current vacuum measurement method generally requires after placing gas cylinder 48 hours
It can carry out, low efficiency of long duration.As the military service quantity of vehicle-mounted LNG gas cylinder is continuously increased, a kind of suitable detection how is found
Method improves detection efficiency, reduces the final purpose that testing cost is invention research.
Currently, there are mainly four types of the vacuum measurement methods of vehicle-mounted LNG gas cylinder：Flowmeter method, weight method, pressure gradient method
With surface temperature method.（1）Flowmeter method is in the case where certain environment temperature and atmospheric pressure, using gas mass flow
The gas mass flow in cooling water of units of measurement time in detected pieces after liquid evaporation by flowmeter is counted, the gas measured then is utilized
Mass flow calculation tests evaporation rate and static evaporation rate, so that it is determined that the method for gas cylinder layer vacuum.This method needs
At least 48h is stood after gas cylinder filling liquid, detection time is longer, be not suitable for mounted gas cylinder in X -ray inspection X.（2）Weighing rule
It is to obtain cylinder filling liquid in a period of time by weighing gas cylinder weight and leak out the quality of gas cylinder through evaporation, and then determine gas
The method of bottle layer vacuum.This method also needs to stand at least 48h after gas cylinder filling liquid, and detection time is longer, no
Suitable for mounted gas cylinder in X -ray inspection X.（3）Pressure gradient method is after absorbing heat by measurement gas cylinder internal, and LNG gasification is led
Cause inner liner pressure increase, record pressure rise versus time curve speculate layer vacuum whether He Ge method.The party
It can be obtained effective testing result within method general 6 hours to 12 hours, efficiency is higher.But this method equally exists certain office
It is sex-limited, start test when 2 hours in cylinder liner pressure oscillation it is big, raising is not obvious, only when the time is more than 2 small with
Afterwards, pressure of the inside of a bottle just rises appreciably at any time.（4）Surface temperature method is to carry out stable state by cylinder outer surface and surrounding air
Heat exchange, measure outside wall temperature and environment temperature difference, approximation speculate gas cylinder layer vacuum whether He Ge method.The party
Method is easy to operate, outside wall surfaces temperature and the ambient enviroment convective heat transfer such as can directly detect the temperature of cylinder outer surface, but need
After stabilization, just it can be evaluated as a result, the time is longer.
Summary of the invention
For overcome the deficiencies in the prior art, the purpose of the present invention is to provide a kind of low temperature LNG gas cylinder layer vacuums
Rapid detection method.This method fills low temperature cylinder surface bottleneck, the middle part, the measurement point of tail portion three of completion by continuously measurement
Temperature value, and data are depicted as temperature change measured curve, are compared with measured curve and corresponding assessment curve.It comments
Curve is estimated by qualified vacuum degree（5Pa）Under the conditions of same model specification gas cylinder, obtained after test of many times is corrected.If gas cylinder
The curve of 3 test points is with assessment curve co-insides or above assessment curve, then gas cylinder vacuum degree verifies as qualification, table
Bright current vacuum level can be effectively insulated；Otherwise, gas cylinder vacuum degree verifies as unqualified.This method have it is easy to operate, time-consuming,
The features such as high-efficient.
In order to achieve the above-mentioned object of the invention, the technical scheme adopted by the invention is that：
One kind includes the following steps with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method：
Step 1, residual dielectric in LNG gas cylinder is excluded completely, and gas cylinder valve is opened, be placed in the indoor nothing that temperature is 25 DEG C
In the environment of strong convection, 2 hours are stood, makes gas cylinder internal and external temperature that significant change no longer occur.
Surface temperature variation is under equal conditions repeatedly carried out to the low temperature cylinder of vacuum degree qualification according to this Research Team
Monitoring result, a vacuum degree examine qualified low temperature cylinder, and excellent heat insulating performance is filled completion and is placed on 25 DEG C
In environment, the temperature of the surface of gas cylinder will change at any time, and very fast in the variation of preceding 2 hours, after 2 hours variation compared with
Slowly, the surface of gas cylinder temperature is no longer changed after standing 24 hours.If gas cylinder layer vacuum is high, gas cylinder insulation effect is good,
Hull-skin temperature decrease speed is slow after then LNG is filled, otherwise decrease speed is fast.Based on this principle, the present invention is using measurement 2
Whether the fall off rate of the surface of gas cylinder temperature and assessment curve comparison, qualified for assessing gas cylinder layer vacuum in hour.
Step 2, the bottleneck outside gas cylinder, middle part and tail position take measurement point one respectively, labeled as A point, B point and
C point installs thermocouple and signal transmitting device on 3 positions；
Preferably, A point, B point and C point are chosen along same axis direction, and the axis and horizontal gas bottle central axis are contour.Wherein B
Point is located in the middle part of body, and A point and C point are located at bottle mouth of gas cylinder and tail portion.It should be far from outer cylinder and liner metal when 3 points of selections
It is directly connected to position.
Preferably, measurement frequency is 0.2 time/second when measured into trip temperature A point, B point and C point.
Step 3, LNG medium is filled into gas cylinder, while continuous measurement in 2 hours is carried out to the temperature of A point, B point and C point,
LNG closes imported valve after the completion of filling.The data continuously measured should be sent to data processing platform (DPP) in real time within 2 hours, and draw
At the measured curve changed over time；
Step 4, the assessment curve under the measured curve of A point, B point and C point in 2 hours and qualified vacuum degree condition is carried out pair
Than, if 3 measured curves are with assessment curve co-insides or above assessment curve, gas cylinder vacuum degree verifies as qualification,
Show that current vacuum level can be effectively insulated；Otherwise, then gas cylinder vacuum degree verify as it is unqualified.
Assessment curve is qualified by choosing same model specification, layer vacuum（5Pa）Low temperature cylinder 3, every
Gas cylinder carries out continuous temperature measurement to A point, B point and C point under the conditions of environment temperature is 25 DEG C（2 hours）3 times, then every bit obtains
9 groups of observed temperature datas are obtained, point assessment curve is obtained by 9 groups of observed temperature data data envelopment fittings.
Compared with prior art, advantage is as follows by the present invention：
1, gas cylinder vacuum degree is detected indirectly with the method for measurement the surface of gas cylinder temperature, method is simple and easy to operate.
2, this method test process only needs to paste thermocouple in LNG the surface of gas cylinder and by conducting wire connection signal transmitter
With data processing platform (DPP), does not need to build complicated testing stand, effectively reduce testing cost.
3, compared with flowmeter method, weight method, surface temperature method, this method only needs 4 hours can obtain testing result,
Detection cycle is short, high-efficient.
Therefore, it the advantages of both comprehensive pressure gradient method and surface temperature method of the present invention, proposes a kind of improved based on table
The low temperature LNG gas cylinder vacuum degree rapid detection method of face temperature method.This method can quickly detect layer vacuum in 4 hours
Whether qualified, checkability is high；This method can be detected directly from cylinder outer surface simultaneously, easy to operate；The last party
Method can fill the whole process that later the surface of gas cylinder temperature changes over time with complete measurement LNG, and detection method is rigorous.
Detailed description of the invention
Fig. 1 is gas cylinder layer vacuum detection schematic diagram；
Fig. 2 is A point assessment curve graph；
Fig. 3 is B point assessment curve graph；
Fig. 4 is C point assessment curve graph；
Fig. 5 is measured curve and assessment curve comparison figure.
Wherein, 1, low temperature cylinder；2, thermocouple；3, signal transmitting device；4, data processing platform (DPP)；5, curve is assessed；6, real
Survey curve（Vacuum degree is qualified）；7, measured curve（Vacuum degree is unqualified）.
Specific embodiment
Following further describes the present invention with reference to the drawings.
Embodiment 1
Embodiment 1 uses volume to establish assessment curve, and the LNG low temperature for being 375L for volume for the LNG low temperature cylinder of 375L
Gas cylinder carries out the assessment of gas cylinder layer vacuum.
The completion before being plotted in the detection of gas cylinder layer vacuum of assessment curve.Low temperature cylinder vacuum degree measurement is built first
Testing stand selects low temperature cylinder 3 that same model specification vacuum degree is 5Pa.Residual dielectric in every low temperature cylinder is excluded
Completely, and by gas cylinder valve it opens, is placed in the indoor environment without strong convection that temperature is 25 DEG C and stands 2 hours, make in gas cylinder
Significant change no longer occurs for outer temperature.3 points, respectively A point, B point and C are chosen in the same axis direction sequence of cylinder outer surface
Point, and B point is located in the middle part of body, A point and C point are located at bottle mouth of gas cylinder and tail portion, and the distance of A point and C point distance B point is
50cm.LNG medium is filled into gas cylinder, while continuous temperature is carried out to gas cylinder A point, B point and C point with the measurement frequency of 0.2 time/second
Degree measurement（2 hours）Totally 3 times, the temperature variation data of record A point, B point and C point.It 3 gas cylinders each point measurement 3 times, can get
It totally 9 groups of temperature variation data, is fitted to obtain the assessment curve of A point, B point and C point by this 9 groups of temperature variation data lower envelope lines,
It is as shown in Figure 2, Figure 3 and Figure 4 respectively.
When being detected to low-temperature gas cylinder sandwich layer vacuum degree, as shown in Figure 1, firstly, low temperature LNG gas cylinder valve to be measured is beaten
It opens, is placed in the interior that temperature is 25 DEG C without standing 2 hours in strong convection environment, gas cylinder internal and external temperature is made no longer to occur obviously to become
Change.3 points are chosen in cylinder outer surface, respectively A point, B point and C point are chosen identical when position is with assessment curve plotting.Its
It is secondary, thermocouple is individually fixed in A point, B point and C point, LNG medium is filled into gas cylinder, while thermocouple is with 0.2 time/second
Frequency measure respectively A point, B point and C point temperature data and be sent to data processing platform (DPP), time of measuring reach 2 hours stop
Measurement.Finally, data processing platform (DPP) reads the temperature data of A point, B point and C point and is depicted as the temperature reality of A point, B point and C point
Survey curve.
The temperature measured curve of A point, B point and C point is compared with corresponding assessment curve, as shown in Figure 5.If A point,
The temperature measured curve of B point and C point is with assessment curve co-insides or above assessment curve, then gas cylinder vacuum degree is qualified
（Curve 6）；Otherwise gas cylinder vacuum degree is unqualified（Curve 7）.
The above description is only an embodiment of the present invention, is not intended to limit the scope of the invention, all to utilize this hair
Method made by bright description is applied directly or indirectly in other relevant technical fields, is similarly included in this hair
In bright scope of patent protection.
Claims (6)
1. a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, which is characterized in that include the following steps：
Step 1, residual dielectric in LNG gas cylinder is excluded completely, and gas cylinder valve is opened, occur that gas cylinder internal and external temperature no longer
Significant change；
Step 2, the bottleneck outside gas cylinder, middle part and tail position take measurement point one respectively, are labeled as A point, B point and C point,
Thermocouple and signal transmitting device are installed on 3 positions；
Step 3, LNG medium is filled into gas cylinder, while to the continuously measuring temperature of A point, B point and C point, after the completion of LNG is filled
Close imported valve；The data continuously measured are sent to data processing platform (DPP) in real time, and are depicted as the actual measurement changed over time song
Line；
Step 4, the assessment curve under the measured curve of the A point, B point and the C point that continuous measurement are obtained and qualified vacuum degree condition
It compares, if 3 points of measured curve is with assessment curve co-insides or above assessment curve, gas cylinder vacuum degree is verified as
Qualification shows that current vacuum level can be effectively insulated；Otherwise, then gas cylinder vacuum degree verify as it is unqualified.
2. described in claim 1 a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, it is characterised in that step（1）
In, LNG gas cylinder is placed in the indoor environment without strong convection that temperature is 25 DEG C, and time of repose 2 hours.
3. described in claim 1 a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, it is characterised in that step（2）
In, A point, B point and C point are chosen along same axis direction, and the axis and horizontal gas bottle central axis are contour, 3 points far from outer cylinder and
Liner metal is directly connected to position.
4. described in claim 1 a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, it is characterised in that step（3）
In, continuous measuring hours are 2 hours.
5. described in claim 1 a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, it is characterised in that step（3）
In, measurement frequency is 0.2 time/second when measured into trip temperature A point, B point and C point.
6. described in claim 1 a kind of with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method, it is characterised in that step（4）
In, curve is assessed by obtaining after the test of many times curve amendment under qualified vacuum degree condition.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810883745.5A CN108918024A (en) | 2018-08-06 | 2018-08-06 | One kind is with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method |
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| CN201810883745.5A CN108918024A (en) | 2018-08-06 | 2018-08-06 | One kind is with low-temperature gas cylinder sandwich layer vacuum degree rapid detection method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111222796A (en) * | 2020-01-09 | 2020-06-02 | 西安交通大学 | Method and device for measuring vacuum degree of LNG pipeline based on temperature field principle, storage medium and terminal equipment |
| CN114458940A (en) * | 2022-01-18 | 2022-05-10 | 中车长江运输设备集团有限公司 | Vacuum degree early warning method for liquid hydrogen transportation equipment |
| CN115111529A (en) * | 2022-08-02 | 2022-09-27 | 兰州理工大学 | Interlayer vacuum degree monitoring and alarming method and system for low-temperature Dewar |
| CN115111529B (en) * | 2022-08-02 | 2024-04-26 | 兰州理工大学 | Sandwich vacuum degree monitoring and alarming method and system for low-temperature Dewar |
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| CN2369233Y (en) * | 1999-04-28 | 2000-03-15 | 中国科学院金属研究所 | Infrared optical waveguide temperature vacuum tester |
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| WO2018129571A1 (en) * | 2017-01-16 | 2018-07-19 | Cryoshelter Gmbh | Device and method for determining the thermal insulation quality of twin-walled, vacuum-insulated containers |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111222796A (en) * | 2020-01-09 | 2020-06-02 | 西安交通大学 | Method and device for measuring vacuum degree of LNG pipeline based on temperature field principle, storage medium and terminal equipment |
| CN114458940A (en) * | 2022-01-18 | 2022-05-10 | 中车长江运输设备集团有限公司 | Vacuum degree early warning method for liquid hydrogen transportation equipment |
| WO2023138567A1 (en) * | 2022-01-18 | 2023-07-27 | 中车长江运输设备集团有限公司 | Early warning and alarm method for vacuum degree of liquid hydrogen transportation equipment |
| CN115111529A (en) * | 2022-08-02 | 2022-09-27 | 兰州理工大学 | Interlayer vacuum degree monitoring and alarming method and system for low-temperature Dewar |
| CN115111529B (en) * | 2022-08-02 | 2024-04-26 | 兰州理工大学 | Sandwich vacuum degree monitoring and alarming method and system for low-temperature Dewar |
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