CN110907151A - Method for measuring and calculating relationship between vacuum degree of low-temperature gas cylinder and daily evaporation rate and adsorption capacity - Google Patents
Method for measuring and calculating relationship between vacuum degree of low-temperature gas cylinder and daily evaporation rate and adsorption capacity Download PDFInfo
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Abstract
The invention discloses a method for measuring and calculating the relationship between the vacuum degree of a low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity, which comprises the following steps: (1) preparing a measuring device; (2) measuring and calculating the basic values of the background interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas cylinder filled with the low-temperature liquid; (3) filling trace gas into the interlayer of the low-temperature gas cylinder for multiple times to reduce the vacuum degree of the interlayer of the low-temperature gas cylinder, and measuring and calculating the interlayer vacuum degree, static daily evaporation rate and adsorption capacity of the low-temperature gas cylinder after each gas filling; (4) drawing a change relation curve of the vacuum degree of the interlayer and the static daily evaporation rate according to the recorded vacuum degree of the interlayer and the static daily evaporation rate; and drawing an actual adsorption isotherm according to the recorded interlayer vacuum degree after each inflation and the corresponding adsorption amount. The measuring and calculating method can measure and calculate the change relation between the vacuum degree of the interlayer of the low-temperature gas cylinder after air leakage and air release and the static daily evaporation rate and the adsorption quantity, and can show the change relation through a drawn curve.
Description
Technical Field
The invention relates to the field of low-temperature gas cylinders for storing low-temperature liquid, in particular to a method for measuring and calculating the relation between the vacuum degree of a low-temperature gas cylinder and the daily evaporation rate and the adsorption quantity.
Background
A cryogenic gas cylinder is a vacuum insulated container for storage and transportation of cryogenic liquids such as: the low-temperature gas cylinder comprises an outer cylinder body and an inner cylinder body positioned in the outer cylinder body, an interlayer between the inner cylinder body and the outer cylinder body is a vacuum heat insulation layer, and an adsorbent used for adsorbing gas so as to maintain vacuum is also placed in the interlayer; the vacuum degree of the low-temperature gas cylinder refers to the vacuum degree of an interlayer of the low-temperature gas cylinder, the service life of the low-temperature gas cylinder is closely related to the vacuum life of a heat insulation interlayer of the low-temperature gas cylinder, when the vacuum of the interlayer of the low-temperature gas cylinder deteriorates, the heat insulation performance is reduced along with the deterioration of the vacuum of the interlayer, and the service value of the low-temperature gas cylinder is lost when the vacuum of the interlayer deteriorates, namely the vacuum life of the low-temperature gas cylinder is ended, and the vacuum life of the low-temperature gas; therefore, if the vacuum life span of the interlayer of the low-temperature gas cylinder can be mastered, a maintenance plan can be arranged in the vacuum life span, the vacuum pumping can be carried out again, and the like, so that the method has very important significance for prolonging the service time of the low-temperature gas cylinder and ensuring the safe production.
The interlayer vacuum degree of the low-temperature gas cylinder is influenced by gas leakage of the cylinder body and gas release of an interlayer material, the gas leakage of the cylinder body refers to gas leakage of the outer cylinder body or gas leakage of the inner cylinder body, external air can leak into the interlayer when the outer cylinder body leaks gas, and low-temperature liquid or evaporated gas of the low-temperature liquid can leak into the interlayer when the inner cylinder body leaks gas; the interlayer material outgassing refers to the release of gas from the wall of the bottle body and the material in the interlayer to the interlayer space, and the outgassing amount of the interlayer material outgassing is small, and generally mainly takes hydrogen as main gas.
At present, due to the lack of the change relationship between the vacuum degree and the adsorption quantity of the interlayer of the low-temperature gas cylinder after gas leakage or material deflation and the change relationship between the vacuum degree of the interlayer and the static daily evaporation rate, the vacuum life span of the interlayer of the low-temperature gas cylinder after gas leakage or material deflation is difficult to evaluate.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity after trace gas leaks into the interlayer or trace hydrogen is put into the interlayer material is provided.
In order to solve the problems, the technical scheme adopted by the invention is as follows: the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity is characterized by comprising the following steps of: the method comprises the following steps:
(1) preparing a measuring device, the measuring device comprising: the device comprises a mass flow meter, a vacuum measuring pipeline, a vacuum gauge, a burette, a vacuum fine adjustment valve, silicon oil, a vacuum valve, an evacuation valve, an air source and a vacuum unit; one port of a vacuum measuring pipeline is connected with one port of a vacuum valve, the other port of the vacuum valve is connected with one port of an air source valve through a pipeline, the other port of the air source valve is connected with an air outlet of an air source through a pipeline, a burette is inverted, a valve on the burette is opened, an inlet of the burette is immersed into silicon oil, a tip outlet of the burette is connected with one end of a vacuum fine adjustment valve through a pipeline, the other end of the vacuum fine adjustment valve and a vacuum gauge are respectively connected with a vacuum measuring pipeline through pipelines, an air pumping port of a vacuum unit is connected with one port of an evacuation valve through a pipeline, and the other port of the evacuation valve is connected with a pipeline between the vacuum valve and the air source valve through a pipeline; 1-1, the measurement of the interlayer vacuum degree of the low-temperature gas cylinder by using the measurement device comprises the following steps: 1-1-1, connecting the outlet of the container pumping nozzle of the low-temperature gas cylinder interlayer with the other end of the vacuum measurement pipeline; 1-1-2, under the condition of ensuring that the container evacuating nozzle is not opened, closing vacuum fine adjustmentThe valve and the air source valve open the vacuum valve and the evacuation valve, and the vacuum unit is started to evacuate the vacuum measurement pipeline; 1-1-3, when the measured value of the vacuum gauge reaches 1 x 10-2When Pa, closing the vacuum valve, opening the container evacuating nozzle, recording the measurement value of the vacuum gauge after stabilization, wherein the measurement value is the interlayer vacuum degree of the low-temperature gas cylinder, and closing the container evacuating nozzle after the measurement is finished; 1-2, the measuring and calculating steps of the static daily evaporation rate of the low-temperature gas cylinder by using the measuring device are as follows: 1-2-1, connecting an inlet of a mass flow meter with an evaporated gas outlet of a low-temperature gas cylinder through a pipeline, opening the evaporated gas outlet, and closing other valves of the low-temperature gas cylinder; 1-2-2, standing the low-temperature gas cylinder; 1-2-3, recording the accumulated flow and the ambient temperature of the mass flowmeter after the measured value of the mass flowmeter is stable, and then calculating the stable accumulated flow q averaged for 24h according to the recorded accumulated flowmUnit is m3D and calculating the average ambient temperature T from the recorded ambient temperatureshIn units of; 1-2-4. by the formula
Calculating to obtain the static daily evaporation rate α with the unit of%/d and rho0Is the density of the cryogenic liquid stored in the cryogenic gas cylinder at standard atmospheric pressure in kg/m3η is the temperature calibration coefficient of the mass flowmeter, V is the effective volume of the low-temperature gas cylinder in m3；TLThe temperature of the cryogenic liquid stored in the cryogenic gas cylinder at the standard atmospheric pressure is represented by K; t is ambient temperature, and T is 273+ ThIn units of K;
(2) calculating the background interlayer vacuum degree and the static daily evaporation rate basic value of the low-temperature gas cylinder filled with the low-temperature liquid by referring to the steps 1-1 and 1-2;
(3) simulating leakage of trace gas or deflation of interlayer materials, filling the trace gas into the interlayer of the low-temperature gas cylinder filled with the low-temperature liquid for multiple times to accelerate the reduction of the vacuum degree of the interlayer of the low-temperature gas cylinder, and calculating the interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas cylinder by referring to the steps of 1-1 and 1-2 after filling the gas each time; the charging step of each gas and the calculation of the cumulative charging amount are as follows: 3-1, closing the container evacuation nozzle, the air source valve and the vacuum fine-tuning valve, opening the vacuum valve and the evacuation valve, starting the vacuum unit to evacuate the vacuum measurement pipeline, and when the measurement value of the vacuum gauge reaches 10-2When the pressure is within the range of Pa, the evacuation valve is closed, and the gas source valve is opened, so that the gas in the gas source is filled into the vacuum measurement pipeline; slowly opening the vacuum fine-tuning valve to ensure that the original gas in the burette is extruded out of the burette by the gas filled in the vacuum measuring pipeline in a bubbling mode into the silicon oil to be replaced; 3-2, closing the air source valve and the vacuum fine adjustment valve, opening the evacuation valve to enable the vacuum unit to evacuate the vacuum measurement pipeline, slowly opening the vacuum fine adjustment valve during evacuation, debugging and lifting the silicon oil liquid surface in the burette to a scale, recording the scale at the moment as a first scale, and then closing the vacuum fine adjustment valve; 3-3, when the measured value of the vacuum gauge reaches 10-2When the pressure is within the range of Pa, closing the vacuum valve, opening a container evacuation nozzle, and slowly opening the vacuum fine adjustment valve to enable gas in the burette to be filled into the interlayer of the low-temperature gas cylinder, and when the silicon oil liquid surface in the burette rises to a preset scale, closing the vacuum fine adjustment valve, and recording the scale at the moment as a second scale; monitoring the pressure in the pipeline by using a vacuum gauge, and closing a container evacuating nozzle after the pressure is stable; 3-4. through the formula
Calculating to obtain the quantity Q of gas charged for the nth timeKnIn the unit of Pa.m3，VgIs the volume between the first scale and the second scale in the burette and has the unit of m3，PKnThe gas pressure in the burette is measured after the interlayer of the low-temperature gas cylinder is inflated, and the unit is Pa, PKnP- ρ gh, P being the ambient atmospheric pressure, ρ being the silicone oil density in kg/m3H is the height between the second scale and the first scale, the unit is m, g is the unit of gravity, g is 9.8N/kg, Tn is the ambient temperature when the gas is filled, and the unit is K; 3-5, respectively charging the gas quantity QKnAccumulating to obtain the accumulated inflation quantity Q after the nth inflationn(ii) a By the formula
Calculating to obtain the adsorption quantity Q of the gas adsorbed by each gram of low-temperature adsorbent after aerationmIn the unit of Pa.m3W is the mass of the low-temperature adsorbent in the interlayer of the low-temperature gas cylinder, and the unit is g;
(4) drawing a change relation curve of the interlayer vacuum degree and the static daily evaporation rate according to the recorded basic values of the background interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas cylinder at the low temperature and the interlayer vacuum degree and the static daily evaporation rate after each inflation; and drawing an actual adsorption isotherm according to the recorded vacuum degree of the interlayer of the low-temperature gas cylinder after each inflation and the corresponding adsorption amount.
Further, the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity comprises the following steps: before measuring the interlayer vacuum degree of the low-temperature gas cylinder by using a measuring device, the leakage and deflation rate of the vacuum measuring pipeline is required to be measured and calculated, the phenomenon that the pipeline leakage and deflation rate is too high to influence the interlayer vacuum degree measuring result is prevented, and when the pipeline leakage and deflation rate obtained by measurement and calculation is less than or equal to 2 multiplied by 10-7Pa·m3The vacuum degree of the interlayer of the low-temperature gas cylinder can be measured only when the pressure is in the second range; the steps of measuring and calculating the leakage and deflation rate of the pipeline are as follows: a. closing the container evacuation nozzle, the vacuum fine-tuning valve and the air source valve, opening the vacuum valve and the evacuation valve, and starting the vacuum unit to evacuate the vacuum measurement pipeline; b. when the measured value of the vacuum gauge is less than 1 multiplied by 10-2After Pa, the vacuum valve is closed and the measurement of the vacuum gauge at this time is recorded as P01Pa, 2min later the vacuum gauge measurement is recorded again as P02In Pa; c. by the formula
Calculating to obtain the leakage and deflation rate Q of the pipeline0In the unit of Pa.m3/s，V0Is the volume of the pipeline between the vacuum fine-tuning valve, the vacuum valve and the container vacuum nozzle, and the unit is m3。
Further, the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity comprises the following steps: 3-1 step was repeated twice, so that the gas in the burette was completely replaced by the gas in the gas source.
Further, the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity comprises the following steps: the accuracy of the mass flowmeter is not lower than 1%.
Further, the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity comprises the following steps: the vacuum gauge has a measuring range of 105Pa～10-5The precision of the Pa compound vacuum gauge is not lower than 15%.
Further, the method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity comprises the following steps: the silicone oil is diffusion pump silicone oil.
The invention has the advantages that: the measuring and calculating method can accelerate the process of simulating the deflation of the interlayer material or the leakage of trace gas into the interlayer by filling trace gas into the interlayer of the low-temperature gas cylinder through the measuring device, so that the vacuum degree of the interlayer of the low-temperature gas cylinder can be accelerated to be reduced, and the vacuum degree, the static daily evaporation rate and the adsorption quantity of the interlayer after each inflation can be measured and calculated through the measuring device in the process, so that a plurality of groups of data of the vacuum degree, the static daily evaporation rate and the adsorption quantity of the interlayer can be obtained, and the actual adsorption isotherm of the vacuum degree and the adsorption quantity of the interlayer and the change relation curve of the vacuum degree and the static daily evaporation rate of the interlayer can be drawn, thereby providing a foundation for the evaluation of the vacuum.
Drawings
Fig. 1 is a schematic structural diagram of a measuring device according to the present invention.
FIG. 2 is an exemplary graph of the relationship between the vacuum degree of the interlayer and the static daily evaporation rate.
FIG. 3 is an exemplary graph of the actual adsorption isotherm of the degree of vacuum and the amount of adsorption of the interlayer of the present invention.
Detailed Description
The present invention will be described in further detail below with reference to specific embodiments and the attached drawings.
The method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity comprises the following steps:
(1) preparing the measuring device, as shown in FIG. 1The measuring device comprises: the device comprises a mass flow meter 1, a vacuum measuring pipeline 2, a vacuum gauge 3, a burette 52, a vacuum fine adjustment valve 51, silicon oil 5, a vacuum valve 6, an evacuation valve 71, an air source valve 81, an air source 8 and a vacuum unit 7; in the embodiment, the precision of the mass flowmeter 1 is not lower than 1%; the vacuum gauge 3 has a measuring range of 105Pa～10-5The precision of the Pa compound vacuum gauge is not lower than 15%; the silicone oil 5 is commercially available diffusion pump silicone oil, and the burette 52 uses the diffusion pump silicone oil to quantify gas, because the saturated vapor pressure of the diffusion pump silicone oil is low, the gas with required quantification cannot be influenced; one port of the vacuum measuring pipeline 2 is connected with one port of the vacuum valve 6, the other port of the vacuum valve 6 is connected with one port of the air source valve 81 through a pipeline, the other port of the air source valve 81 is connected with an air outlet of the air source 8 through a pipeline, the burette 52 is inverted, a valve on the burette 52 is opened, an inlet of the burette 52 is immersed into the silicon oil 5, a tip outlet of the burette 52 is connected with one end of the vacuum fine adjustment valve 51 through a pipeline, the other end of the vacuum fine adjustment valve 51 and the vacuum gauge 3 are respectively connected with the vacuum measuring pipeline 2 through pipelines, an air suction port of the vacuum unit 7 is connected with one port of the evacuation valve 71 through a pipeline, and the other port of the evacuation valve 71 is connected with a pipeline between the vacuum valve 6 and the air source valve 81 through a pipeline; 1-1, the measurement of the interlayer vacuum degree of the low-temperature gas cylinder 9 by using the measurement device comprises the following steps: 1-1-1, connecting the outlet of a container evacuating nozzle 21 of an interlayer of a low-temperature gas cylinder 9 with the other end of a vacuum measuring pipeline 2, wherein the container evacuating nozzle 21 is arranged on the interlayer evacuating pipeline of the low-temperature gas cylinder 9, when the low-temperature gas cylinder 9 is normally used, the container evacuating nozzle 21 is closed, and only when the low-temperature gas cylinder 9 needs to be evacuated, the container evacuating nozzle 21 is opened; 1-1-2, under the condition that the container evacuating nozzle 21 is not opened, closing the vacuum fine-tuning valve 51 and the air source valve 81, opening the vacuum valve 6 and the evacuating valve 71, and starting the vacuum unit 7 to evacuate the vacuum measuring pipeline 2; 1-1-3, when the vacuum gauge 3 measures to reach 1X 10-2When Pa, closing the vacuum valve 6, opening the container evacuating nozzle 21, recording the measured value of the vacuum gauge 3 after stabilization, wherein the measured value is the interlayer vacuum degree of the low-temperature gas cylinder 9 and has the unit of Pa, and closing the container evacuating nozzle 21 after the measurement is finished; 1-2. Using the above mentioned assayThe measuring and calculating steps of the measuring device for the static daily evaporation rate of the low-temperature gas cylinder 9 are as follows: 1-2-1, connecting an inlet of a mass flow meter 1 with an evaporation gas outlet of a low-temperature gas cylinder 9 through a pipeline, opening the evaporation gas outlet, and closing other valves of the low-temperature gas cylinder 9; 1-2-2, standing the low-temperature gas cylinder 9; 1-2-3, recording the accumulated flow and the ambient temperature of the mass flowmeter 1 after the measured value of the mass flowmeter 1 is stable, and then calculating the stable accumulated flow q with the average of 24h according to the recorded accumulated flowmUnit is m3D and calculating the average ambient temperature T from the recorded ambient temperatureshIn units of; 1-2-4. by the formula
Calculating to obtain the static daily evaporation rate α with the unit of%/d and rho0The density of the cryogenic liquid stored in the cryogenic gas cylinder 9 at standard atmospheric pressure is expressed in kg/m3η is the temperature calibration coefficient of the mass flowmeter 1, V is the effective volume of the low-temperature gas cylinder 9 in m3；TLThe temperature of the cryogenic liquid stored in the cryogenic gas cylinder 9 at the standard atmospheric pressure is represented by K; t is ambient temperature, and T is 273+ ThIn units of K; d represents day;
(2) calculating the background interlayer vacuum degree and the static daily evaporation rate basic value of the low-temperature gas cylinder 9 filled with the low-temperature liquid by referring to the steps 1-1 and 1-2; the background interlayer vacuum degree is the original interlayer vacuum degree of the low-temperature gas cylinder 9 at the moment;
(3) simulating leakage of trace gas or deflation of interlayer material, filling the trace gas into the interlayer of the low-temperature gas bottle 9 filled with low-temperature liquid for multiple times to accelerate the reduction of the vacuum degree of the interlayer of the low-temperature gas bottle 9, wherein the gas in the gas source 8 is hydrogen, helium or evaporated gas of the low-temperature liquid stored in the low-temperature gas bottle 9, and measuring and calculating the interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas bottle 9 by referring to the steps of 1-1 and 1-2 after filling the gas each time; the step of charging the gas, and the calculation of the cumulative charge, are as follows: 3-1, closing the container evacuating nozzle 21, the air source valve 81 and the vacuum fine adjustment valve 51, opening the vacuum valve 6 and the evacuating valve 71, starting the vacuum unit 7 to evacuate the vacuum measuring pipeline 2, and when the vacuum gauge is used3 up to 10-2In the range of Pa, the evacuation valve 71 is closed, and the gas source valve 81 is opened, so that the gas in the gas source 8 is filled into the vacuum measurement pipeline 2; slowly opening the vacuum fine-adjustment valve 51 to enable the original gas in the burette 52 to be extruded out of the burette 52 in a bubbling mode into the silicon oil 5 by the filling gas in the vacuum measuring pipeline 2 to be replaced, and repeating the steps again to enable the interior of the burette 52 to be completely replaced by the gas in the gas source 8; 3-2, closing the air source valve 81 and the vacuum fine-tuning valve 51, opening the evacuation valve 71 to enable the vacuum unit 7 to evacuate the vacuum measurement pipeline 2, slowly opening the vacuum fine-tuning valve 51 during evacuation, debugging and lifting the silicon oil liquid surface in the burette 52 to a scale, recording the scale at the moment as a first scale, and then closing the vacuum fine-tuning valve 51; 3-3, when the measured value of the vacuum gauge 3 reaches 10-2In the range of Pa, closing the vacuum valve 6, opening the container evacuation nozzle 21, and slowly opening the vacuum fine-tuning valve 51, so that the gas in the burette 52 can be filled into the interlayer of the low-temperature gas cylinder 9, and when the silicon oil liquid level in the burette 52 rises to a preset scale, closing the vacuum fine-tuning valve 51, and recording the scale at the moment as a second scale; the pressure in the pipe at this time is monitored by the vacuum gauge 3, and when the pressure is stabilized, the container evacuation nozzle 21 is closed; 3-4. through the formula
Calculating to obtain the quantity Q of gas charged for the nth timeKnIn the unit of Pa.m3，VgIs the volume between the first scale and the second scale in the burette 52 and has a unit of m3，PKnThe gas pressure in the burette 52 is Pa, P after the interlayer of the low-temperature gas bottle 9 is inflatedKnP- ρ gh, P being the ambient atmospheric pressure, ρ being the silicone oil density in kg/m3H is the height between the second scale and the first scale, the unit is m, g is the unit of gravity, g is 9.8N/kg, Tn is the ambient temperature when the gas is filled, and the unit is K; 3-5, respectively charging the gas quantity QKnAccumulating to obtain the accumulated inflation quantity Q after the nth inflationn(ii) a By the formula
Calculating to obtain the adsorption quantity Q of the gas adsorbed by each gram of low-temperature adsorbent after aerationmIn the unit of Pa.m3W is the mass of the low-temperature adsorbent in the interlayer of the low-temperature gas cylinder 9, and the unit is g;
(4) drawing a change relation curve of the interlayer vacuum degree and the static daily evaporation rate shown in figure 2 according to the recorded basic values of the background interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas cylinder 9 at the low temperature and the interlayer vacuum degree and the static daily evaporation rate after each inflation; and drawing an actual adsorption isotherm as shown in fig. 3 according to the recorded interlayer vacuum degree of the low-temperature gas cylinder 9 after each inflation and the corresponding adsorption amount.
In this embodiment, the background interlayer vacuum degree of the cryogenic gas cylinder 9 at normal temperature is measured with reference to step 1-1 before step 2, so as to confirm the interlayer vacuum performance state of the cryogenic gas cylinder 9 before testing.
In the embodiment, before measuring the interlayer vacuum degree of the low-temperature gas cylinder 9 by using the measuring device, the leakage and deflation rate of the vacuum measuring pipeline 2 needs to be measured and calculated each time, so that the phenomenon that the pipeline leakage and deflation rate is too high to influence the interlayer vacuum degree measuring result is prevented, and when the pipeline leakage and deflation rate obtained by measurement and calculation is less than or equal to 2 multiplied by 10-7Pa·m3Only when the vacuum degree of the interlayer of the low-temperature gas cylinder 9 is measured in s; and if the gas leakage and discharge rate of the pipeline is not qualified, helium mass spectrum leakage detection is required to be carried out on each part of the vacuum measurement pipeline 2, and the vacuum measurement pipeline 2 is reset.
The steps of measuring and calculating the leakage and deflation rate of the pipeline are as follows: a. closing the container evacuating nozzle 21, the vacuum fine-tuning valve 51 and the air source valve 81, opening the vacuum valve 6 and the evacuating valve 71, and starting the vacuum unit 7 to evacuate the vacuum measuring pipeline 2; b. when the vacuum gauge 3 measures less than 1X 10-2After Pa, the vacuum valve 6 is closed and the measurement P of the vacuum gauge 3 at this time is recorded01Pa, 2min later the measurement of the vacuum gauge 3 is recorded again as P02In Pa; c. by the formula
Calculating to obtain the leakage and deflation rate Q of the pipeline0In the unit of Pa.m3/s，V0The volume of the pipe between the vacuum fine adjustment valve 51, the vacuum valve 6 and the container evacuation nozzle 21 is expressed in m3。
The following examples of estimating the vacuum life span of the interlayer 9 of the low-temperature gas cylinder after the trace gas leaks into the interlayer or the interlayer material is put into the trace hydrogen by using the drawn change relation curve of the vacuum degree of the interlayer and the static daily evaporation rate and the actual adsorption isotherm are given:
assume the overview of the cryogenic cylinder 9: the mass of the low-temperature adsorbent arranged in the interlayer is B, the unit is g, no normal-temperature adsorbent exists, and the actual measurement result of the leakage and deflation rate of the low-temperature gas cylinder is as follows: < D, in Pa.m3S; the interlayer vacuum threshold value at the end of the interlayer vacuum life of the low-temperature gas cylinder is E, the unit Pa, E is determined according to the inflection point in the curve of the change relation between the interlayer vacuum degree of the low-temperature gas cylinder and the static daily evaporation rate, and in practical application, E can also be determined according to the national standard; e is F corresponding to the adsorption amount on the actual adsorption isotherm and has a unit of Pa.m3/g；
In the low-temperature state with the low-temperature liquid, the interlayer vacuum life period tau of the low-temperature gas cylinder 9 after a small amount of gas leaks into the interlayer or the interlayer material is filled with a small amount of hydrogen is ((F x B)/D)/365/24/3600, and the unit is year.
Claims (6)
1. The method for measuring and calculating the relationship between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity is characterized by comprising the following steps of: the method comprises the following steps:
(1) preparing a measuring device, the measuring device comprising: the device comprises a mass flow meter, a vacuum measuring pipeline, a vacuum gauge, a burette, a vacuum fine adjustment valve, silicon oil, a vacuum valve, an evacuation valve, an air source and a vacuum unit; one port of the vacuum measuring pipeline is connected with one port of the vacuum valve, the other port of the vacuum valve is connected with one port of the air source valve through a pipeline, the other port of the air source valve is connected with an air outlet of an air source through a pipeline, the burette is inverted, a valve on the burette is opened, an inlet of the burette is immersed into silicon oil, a tip outlet of the burette is connected with one end of the vacuum fine adjustment valve through a pipeline, and the other end of the vacuum fine adjustment valve and the vacuum gauge are respectively connected with the vacuum measuring pipeline through pipelinesThe connection, the air pumping port of the vacuum unit is connected with one port of the evacuation valve through a pipeline, and the other port of the evacuation valve is connected with a pipeline between the vacuum valve and the air source valve through a pipeline; 1-1, the measurement of the interlayer vacuum degree of the low-temperature gas cylinder by using the measurement device comprises the following steps: 1-1-1, connecting the outlet of the container pumping nozzle of the low-temperature gas cylinder interlayer with the other end of the vacuum measurement pipeline; 1-1-2, under the condition that the container evacuation nozzle is not opened, closing the vacuum fine-tuning valve and the air source valve, opening the vacuum valve and the evacuation valve, and starting the vacuum unit to evacuate the vacuum measurement pipeline; 1-1-3, when the measured value of the vacuum gauge reaches 1 x 10-2When Pa, closing the vacuum valve, opening the container evacuating nozzle, recording the measurement value of the vacuum gauge after stabilization, wherein the measurement value is the interlayer vacuum degree of the low-temperature gas cylinder, and closing the container evacuating nozzle after the measurement is finished; 1-2, the measuring and calculating steps of the static daily evaporation rate of the low-temperature gas cylinder by using the measuring device are as follows: 1-2-1, connecting an inlet of a mass flow meter with an evaporated gas outlet of a low-temperature gas cylinder through a pipeline, opening the evaporated gas outlet, and closing other valves of the low-temperature gas cylinder; 1-2-2, standing the low-temperature gas cylinder; 1-2-3, recording the accumulated flow and the ambient temperature of the mass flowmeter after the measured value of the mass flowmeter is stable, and then calculating the stable accumulated flow q averaged for 24h according to the recorded accumulated flowmUnit is m3D and calculating the average ambient temperature T from the recorded ambient temperatureshIn units of; 1-2-4. by the formula
Calculating to obtain the static daily evaporation rate α with the unit of%/d and rho0Is the density of the cryogenic liquid stored in the cryogenic gas cylinder at standard atmospheric pressure in kg/m3η is the temperature calibration coefficient of the mass flowmeter, V is the effective volume of the low-temperature gas cylinder in m3；TLThe temperature of the cryogenic liquid stored in the cryogenic gas cylinder at the standard atmospheric pressure is represented by K; t is ambient temperature, and T is 273+ ThIn units of K;
(2) calculating the background interlayer vacuum degree and the static daily evaporation rate basic value of the low-temperature gas cylinder filled with the low-temperature liquid by referring to the steps 1-1 and 1-2;
(3) simulating leakage of trace gas or deflation of interlayer materials, filling the trace gas into the interlayer of the low-temperature gas cylinder filled with the low-temperature liquid for multiple times to accelerate the reduction of the vacuum degree of the interlayer of the low-temperature gas cylinder, and calculating the interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas cylinder by referring to the steps of 1-1 and 1-2 after filling the gas each time; the charging step of each gas and the calculation of the cumulative charging amount are as follows: 3-1, closing the container evacuation nozzle, the air source valve and the vacuum fine-tuning valve, opening the vacuum valve and the evacuation valve, starting the vacuum unit to evacuate the vacuum measurement pipeline, and when the measurement value of the vacuum gauge reaches 10-2When the pressure is within the range of Pa, the evacuation valve is closed, and the gas source valve is opened, so that the gas in the gas source is filled into the vacuum measurement pipeline; slowly opening the vacuum fine-tuning valve to ensure that the original gas in the burette is extruded out of the burette by the gas filled in the vacuum measuring pipeline in a bubbling mode into the silicon oil to be replaced; 3-2, closing the air source valve and the vacuum fine adjustment valve, opening the evacuation valve to enable the vacuum unit to evacuate the vacuum measurement pipeline, slowly opening the vacuum fine adjustment valve during evacuation, debugging and lifting the silicon oil liquid surface in the burette to a scale, recording the scale at the moment as a first scale, and then closing the vacuum fine adjustment valve; 3-3, when the measured value of the vacuum gauge reaches 10-2When the pressure is within the range of Pa, closing the vacuum valve, opening a container evacuation nozzle, and slowly opening the vacuum fine adjustment valve to enable gas in the burette to be filled into the interlayer of the low-temperature gas cylinder, and when the silicon oil liquid surface in the burette rises to a preset scale, closing the vacuum fine adjustment valve, and recording the scale at the moment as a second scale; monitoring the pressure in the pipeline by using a vacuum gauge, and closing a container evacuating nozzle after the pressure is stable; 3-4. through the formula
Calculating to obtain the quantity Q of gas charged for the nth timeKnIn the unit of Pa.m3，VgIs the volume between the first scale and the second scale in the burette and has the unit of m3，PKnThe gas pressure in the burette is measured after the interlayer of the low-temperature gas cylinder is inflated, and the unit is Pa, PKnP- ρ gh, P being the ambient atmospheric pressureRho is the density of the silicone oil in kg/m3H is the height between the second scale and the first scale, the unit is m, g is the unit of gravity, g is 9.8N/kg, Tn is the ambient temperature when the gas is filled, and the unit is K; 3-5, respectively charging the gas quantity QKnAccumulating to obtain the accumulated inflation quantity Q after the nth inflationn(ii) a By the formula
Calculating to obtain the adsorption quantity Q of the gas adsorbed by each gram of low-temperature adsorbent after aerationmIn the unit of Pa.m3W is the mass of the low-temperature adsorbent in the interlayer of the low-temperature gas cylinder, and the unit is g;
(4) drawing a change relation curve of the interlayer vacuum degree and the static daily evaporation rate according to the recorded basic values of the background interlayer vacuum degree and the static daily evaporation rate of the low-temperature gas cylinder at the low temperature and the interlayer vacuum degree and the static daily evaporation rate after each inflation; and drawing an actual adsorption isotherm according to the recorded vacuum degree of the interlayer of the low-temperature gas cylinder after each inflation and the corresponding adsorption amount.
2. The method for measuring and calculating the relation between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption quantity of the low-temperature gas cylinder according to claim 1, wherein the method comprises the following steps: before measuring the interlayer vacuum degree of the low-temperature gas cylinder by using a measuring device, the leakage and deflation rate of the vacuum measuring pipeline is required to be measured and calculated, the phenomenon that the pipeline leakage and deflation rate is too high to influence the interlayer vacuum degree measuring result is prevented, and when the pipeline leakage and deflation rate obtained by measurement and calculation is less than or equal to 2 multiplied by 10-7Pa·m3The vacuum degree of the interlayer of the low-temperature gas cylinder can be measured only when the pressure is in the second range; the steps of measuring and calculating the leakage and deflation rate of the pipeline are as follows: a. closing the container evacuation nozzle, the vacuum fine-tuning valve and the air source valve, opening the vacuum valve and the evacuation valve, and starting the vacuum unit to evacuate the vacuum measurement pipeline;
b. when the measured value of the vacuum gauge is less than 1 multiplied by 10-2After Pa, the vacuum valve is closed and the measurement of the vacuum gauge at this time is recorded as P01Pa, 2min later the vacuum gauge measurement is recorded again as P02In Pa; c. by the formula
Calculating to obtain the leakage and deflation rate Q of the pipeline0In the unit of Pa.m3/s，V0Is the volume of the pipeline between the vacuum fine-tuning valve, the vacuum valve and the container vacuum nozzle, and the unit is m3。
3. The method for measuring and calculating the relation between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity as claimed in claim 1 or 2, wherein the method comprises the following steps: 3-1 step was repeated twice, so that the gas in the burette was completely replaced by the gas in the gas source.
4. The method for measuring and calculating the relation between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity as claimed in claim 1 or 2, wherein the method comprises the following steps: the accuracy of the mass flowmeter is not lower than 1%.
5. The method for measuring and calculating the relation between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity as claimed in claim 1 or 2, wherein the method comprises the following steps: the vacuum gauge has a measuring range of 105Pa～10-5The precision of the Pa compound vacuum gauge is not lower than 15%.
6. The method for measuring and calculating the relation between the vacuum degree of the low-temperature gas cylinder and the daily evaporation rate and the adsorption capacity as claimed in claim 1 or 2, wherein the method comprises the following steps: the silicone oil is diffusion pump silicone oil.
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Effective date of registration: 20231207 Address after: 215600 Fuxin (morning) road 19, Yang Shi Town, Zhangjiagang City, Suzhou, Jiangsu. Patentee after: Zhangjiagang Furui New Energy Technology Co.,Ltd. Address before: 215600 Zhangjiagang Furui special equipment Co., Ltd., 19 Chenxin Road, yangshe Town, Zhangjiagang City, Suzhou City, Jiangsu Province Patentee before: ZHANGJIAGANG FURUI SPECIAL EQUIPMENT Co.,Ltd. |