CN113358174B - Space free volume measuring method - Google Patents
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- CN113358174B CN113358174B CN202110539277.1A CN202110539277A CN113358174B CN 113358174 B CN113358174 B CN 113358174B CN 202110539277 A CN202110539277 A CN 202110539277A CN 113358174 B CN113358174 B CN 113358174B
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- 238000000034 method Methods 0.000 title claims abstract description 51
- 239000000700 radioactive tracer Substances 0.000 claims abstract description 96
- 238000002347 injection Methods 0.000 claims abstract description 83
- 239000007924 injection Substances 0.000 claims abstract description 83
- 238000005070 sampling Methods 0.000 claims abstract description 59
- 238000005259 measurement Methods 0.000 claims abstract description 23
- 238000009792 diffusion process Methods 0.000 claims abstract description 17
- 239000000203 mixture Substances 0.000 claims description 11
- 238000004364 calculation method Methods 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 10
- 238000009423 ventilation Methods 0.000 claims description 5
- 238000004891 communication Methods 0.000 claims description 2
- 238000000691 measurement method Methods 0.000 abstract description 13
- 239000007789 gas Substances 0.000 description 164
- 238000012360 testing method Methods 0.000 description 15
- 229910018503 SF6 Inorganic materials 0.000 description 5
- 238000007789 sealing Methods 0.000 description 5
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 5
- 229960000909 sulfur hexafluoride Drugs 0.000 description 5
- 239000007788 liquid Substances 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
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- 230000008859 change Effects 0.000 description 1
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- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 238000013076 uncertainty analysis Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F17/00—Methods or apparatus for determining the capacity of containers or cavities, or the volume of solid bodies
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Abstract
The invention relates to the technical field of space free volume measurement, in particular to a space free volume measurement method, which comprises the following steps: step one, enabling the pressure boundary of the space to be measured to be in a sealed state, and measuring the background concentration C of the tracer gas in the space to be measured 0 The method comprises the steps of carrying out a first treatment on the surface of the Step two, according to the determined tracer gas injection concentration C in Injection flow rate q in And injection time t in Injecting trace gas into the space to be detected; step three, according to the determined sampling interval time t s Continuously sampling for multiple times, analyzing the concentration of the trace gas in the sample, and after the diffusion of the trace gas in the space to be tested is confirmed to meet the condition of mixing uniformity for the first time, sampling at intervals t s Continuously sampling for at least ten times; step four, establishing a trace gas average concentration increase curve according to trace gas concentrations and sampling time of all samples and obtaining trace gas average concentration in the space to be detectedStep five, calculating the free volume V of the space to be measured i ：The method has the advantages of high accuracy, strong operability and good applicability.
Description
Technical Field
The invention relates to the technical field of space free volume measurement, in particular to a space free volume measurement method.
Background
In production and scientific research work, there is a problem that the free volume of the space needs to be measured, for example, in a nuclear power station master control room residence test, in order to ensure that the master control room staff is prevented from being damaged by ultra-safe dose radiation and other toxic and harmful substances under accident working conditions, the free volume of the space needs to be accurately measured to calculate the leakage amount.
For free volume measurement, the currently commonly used methods include a geometric measurement method, a volume comparison method, a flowmeter measurement method, a weighing measurement method, a gas calibration method and the like. The geometric measurement method is to directly measure the actual size by using measuring tools such as three coordinates and the like, and calculate the free volume according to the measured size; the volume comparison method is to directly measure other volumes by using the standard volume to determine the free volume of the measured space; the flowmeter measuring method is to fill the measured space with liquid, record the flowmeter time of the flowmeter and calculate the measured space volume; the weighing measurement method is to calculate the free volume by measuring the weight of the measured object, filling the measured object with liquid with known density and confirming the increase of the mass; the gas calibration method is to inject gas into the measured container through the standard container, and measure the pressure and temperature change of the standard container and the measured container to calculate the free volume of the measured space.
Among them, the geometric measurement method has great difficulty in the practical operation for the space with complex internal structure, and the accuracy is also greatly affected. The three methods of volume comparison, flowmeter measurement and weighing measurement are liquid, which are easy to affect the performance of the internal components in the space, and when the internal structure of the measured object is complex, the whole space is difficult to be filled with the liquid, so the three methods have great limitations. The medium of the gas calibration method is gas, but the space to be measured by the method must be ensured to be completely closed, and the volume of the space to be measured is generally relatively small due to the limitation of a standard container.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a space free volume measuring method with high accuracy, strong operability and good applicability, so as to overcome the defects in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme: the space free volume measuring method sequentially comprises the following steps ofThe steps are as follows: step one, enabling the pressure boundary of the space to be measured to be in a sealed state, and measuring the background concentration C of the tracer gas in the space to be measured 0 The method comprises the steps of carrying out a first treatment on the surface of the Step two, according to the determined tracer gas injection concentration C in Injection flow rate q in And injection time t in Injecting trace gas into the space to be detected; step three, a plurality of set sampling points in the space to be measured are at a certain sampling interval time t s Continuously sampling for multiple times, analyzing the concentration of the tracer gas in the obtained sample, and determining that the diffusion of the tracer gas in the space to be tested meets the condition of mixing uniformity for the first time in the sampling process, and determining the sampling interval time t s Continuously sampling for at least ten times; step four, establishing a trace gas average concentration increase curve according to trace gas concentrations and sampling time of all samples and obtaining trace gas average concentration in the space to be detectedStep five, calculating the free volume V of the space to be measured i The calculation formula is as follows: />
Preferably, in the first step, the ventilation rate of the space to be measured is estimated to be a m Determining the phase time control reference as T m And satisfies the following: t (T) m <0.1/A m 。
Preferably, in the second step, the tracer gas injection time is determined to be t in And satisfies the following: t is t in <0.1T m The method comprises the steps of carrying out a first treatment on the surface of the Determination of tracer gas injection concentration C in Providing a trace gas concentration for the selected trace gas source; determining the tracer gas injection flow rate as q in And satisfies the following: q in ×C in ×t in ＝＝C t ×V m Wherein C is t For the target concentration of the trace gas in the space to be measured, V m Is the free volume estimation value of the space to be measured.
Preferably, in the second step, when the tracer gas is injected into the space to be measured, the tracer gas is mixed by a mixing device arranged in the space to be measuredThe tracer gas is mixed in the space to be measured according to the determined mixing time t mix And the diffusion is uniform.
Preferably, the mixing time t mix The method meets the following conditions: t is t mix <0.2T m 。
Preferably, in step three, the sampling interval time t s The method meets the following conditions: t is t s <0.2T m 。
Preferably, in the third step, the mixing uniformity condition is that the deviation of the sample trace gas concentration of each set sampling point from the average value of the sample trace gas concentrations of all set sampling points is not more than 5%.
Preferably, in the second step, a return air pipeline communicated with the space to be measured is arranged outside the space to be measured, and the outlet of the trace gas source is connected to the return air pipeline through a single injection pipeline.
Preferably, in the second step, a plurality of injection points are arranged in the space to be measured, and the outlet of the trace gas source is connected to the plurality of injection points through a plurality of injection pipes.
Compared with the prior art, the invention has obvious progress:
according to the space free volume measuring method, quantitative trace gas is injected into the space to be measured, and then the average concentration of the trace gas after diffusion and mixing in the space to be measured is analyzed through sampling, so that the free volume of the space to be measured can be obtained through calculation according to the concentration, flow and time of the trace gas injection, the background concentration of the trace gas in the space to be measured and the average concentration of the trace gas in the space to be measured after the trace gas is injected, and the problems of high free volume measuring difficulty and poor precision caused by complex structure and more contents of the space to be measured can be solved, and the space free volume measuring method has the advantages of being high in accuracy, strong in operability and good in applicability.
Drawings
FIG. 1 is a schematic diagram of one implementation of the spatial free volume measurement method of the present invention.
Fig. 2 is a schematic diagram of another implementation of the spatial free volume measurement method according to an embodiment of the present invention.
Wherein reference numerals are as follows:
1. space to be measured
2. Trace gas source
3. Mixing device
4. Return air pipeline
5. Air return machine
6. 61, 62 injection pipe
7. Pressure reducing valve
8. 80, 81, 82 stop valve
9. 91, 92 flow controller
10. Flow distributor
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to be limiting.
In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
As shown in fig. 1 and 2, one embodiment of the spatial free volume measurement method of the present invention. The method for measuring free volume of space in this embodiment is used for measuring free volume of space 1 to be measured, and the space 1 to be measured can be any space needing free volume measurement, such as a large building, a closed container, and the like. Specifically, the spatial free volume measurement method of the present embodiment sequentially includes the following steps.
Step one, enabling the pressure boundary of the space 1 to be measured to be in a sealed state, and measuring the background concentration C of the tracer gas in the space 1 to be measured 0 . Background concentration C of tracer gas in space 1 to be measured 0 (unit is m 3 /m 3 ) The background concentration of the trace gas can be measured by the existing trace gas background concentration measuring instrument after sampling in the space 1 to be measured.
Before the free volume measurement test of the space 1 to be measured is performed, the tightness of the pressure boundary of the space 1 to be measured is checked, and the pressure boundary of the space 1 to be measured is ensured to be in a sealed state. The pressure boundary of the space refers to the connection boundary at structures such as boundary doors, boundary penetrating members, vent ducts and inlets and outlets. If the pressure boundary of the space 1 to be tested is provided with an opening, the opening needs to be plugged, so that the pressure boundary of the space 1 to be tested is in a sealed state, the trace gas injected into the space 1 to be tested in the subsequent test process is prevented from being polluted and diluted, and the accuracy of the test result is ensured.
In this embodiment, the sealing state is not a hundred-percent strict sealing without a wire leakage, and because in actual operation, the space 1 to be measured may not be completely sealed due to complicated space structure, more contents, more pressure boundaries and other reasons, preferably, after the pressure boundaries of the space 1 to be measured are subjected to sealing inspection and plugging measures, the space 1 to be measured may be not tightly sealed according to the actual sealing state of the space 1 to be measuredThe possible ventilation rate is estimated to obtain the estimated ventilation rate A of the space 1 to be measured m (1/min) and based on the estimated air exchange rate A of the space to be measured m Determining the phase time control reference as T m (in min), T m The method meets the following conditions: t (T) m <0.1/A m The phase time control reference T m The method can provide a determination reference for time control of each stage in the follow-up free volume measurement test of the space 1 to be measured.
Step two, according to the determined tracer gas injection concentration C in Injection flow rate q in And injection time t in A tracer gas is injected into the space 1 to be measured.
The tracer gas is provided by a tracer gas source 2, preferably a pressurized gas cylinder is used as tracer gas source 2. The type of trace gas is not limited, and preferably, sulfur hexafluoride is used as the trace gas source 2. The concentration of the sulfur hexafluoride tracer gas in the air is extremely small, meanwhile, the property of the sulfur hexafluoride tracer gas is stable, the sulfur hexafluoride tracer gas is not easy to react with other substances, the influence of error signals on a measurement result can be effectively avoided, the measurement accuracy is high, and finally, the average concentration of the tracer gas in the space 1 to be measured is in ppb level, the measurement test can be completed only by a small amount of tracer gas, and the influence on the environment and safety is small.
The duration of the injection of the tracer gas into the space 1 to be measured is not too long, and the reference T may preferably be controlled according to the phase time m Determining the injection time of the trace gas, and determining the injection time of the trace gas as t in (in min), t in The method meets the following conditions: t is t in <0.1T m 。
The concentration of the tracer gas injected into the space 1 to be measured is the concentration of the tracer gas provided by the selected tracer gas source 2, namely: determination of tracer gas injection concentration C in (unit is m 3 /m 3 ) The concentration of trace gas provided for the selected trace gas source 2. The concentration of the trace gas supplied by the trace gas source 2 may be selected according to the actual situation, and sulfur hexafluoride may be preferably used in a concentration of 1ppm to 1000ppm mixed with nitrogen.
The flow rate of the tracer gas injected into the space 1 to be measured can be determined according to the principle of mass conservation of the tracer gas, and the injection flow rate of the tracer gas is determined to be q in (unit is m 3 /min)，q in The method meets the following conditions:
q in ×C in ×t in ＝＝C t ×V m
the formula is a mass conservation formula, wherein C t For the target concentration of the trace gas in the space 1 to be measured, the unit is m 3 /m 3 The target concentration C of the trace gas t Can be determined according to the type of the adopted tracer gas analyzer, and preferably, the target concentration C of the tracer gas t 20ppb to 50ppb; v (V) m For the free volume estimation of the space 1 to be measured, the unit is m 3 The estimated value V of free volume of the space 1 to be measured m Can be obtained by field drawing or estimation according to the drawing of the space 1 to be measured.
Therefore, before the free volume measurement test of the space 1 to be measured is carried out, the tracer gas injection concentration C can be determined according to actual conditions in Injection flow rate q in And injection time t in So that the concentration C of the tracer gas injection can be determined at the time of the test in Injection flow rate q in And injection time t in A fixed amount of trace gas is injected into the space 1 to be measured.
If the tracer gas cannot be sufficiently and uniformly dispersed in the space 1 to be measured after being injected into the space 1 to be measured, errors exist in measurement test results, so that when the tracer gas is injected into the space 1 to be measured, it is preferable that the tracer gas is mixed in the space 1 to be measured for a certain mixing time t by a mixing device 3 arranged in the space 1 to be measured mix And the diffusion is uniform. The mixing device 3 can adopt the existing air mixing equipment, the mixing device 3 is configured in the space 1 to be measured, the mixing device 3 is started when the tracer gas is injected into the space 1 to be measured, the diffusion of the tracer gas in the space 1 to be measured can be accelerated, the time required by uniform concentration diffusion of the tracer gas in the space 1 to be measured is reduced, and the aim of controlling the mixing time for fully and uniformly diffusing the tracer gas in the space 1 to be measured in a shorter time is fulfilledIn order to shorten the overall time consumption of the measurement test and effectively control the measurement error. For example, for a large space 1 to be measured (such as a large building interior space), if the tracer gas injected into the space is mixed by the air supply system of the space, the sufficient mixing may take 15 minutes to 1 hour, and the time required for the sufficient mixing can be controlled to 5 minutes to 10 minutes by adding the mixing device 3 to enhance the mixing. Preferably, the reference T can be controlled according to the phase time m To control the mixing time, mixing time t mix (in min) satisfies: t is t mix <0.2T m 。
In addition, in order to ensure uniform diffusion of the trace gas in the space 1 to be measured, the doors inside the space 1 to be measured need to be opened entirely, and if there is a structure such as a ceiling, a floor, etc. in the space 1 to be measured that separates the space, it is necessary to open a part of the ceiling, the floor, so that the inside (within the pressure boundary) of the space 1 to be measured is communicated entirely.
Step three, a plurality of set sampling points in the space 1 to be measured are at a certain sampling interval time t s Continuously sampling for multiple times, analyzing the concentration of the tracer gas of the obtained sample, and in the sampling process, after the diffusion of the tracer gas in the space 1 to be detected is confirmed to meet the condition of mixing uniformity for the first time, determining the sampling interval time t s At least ten samples were taken.
The plurality of set sampling points in the space 1 to be measured may be determined according to the internal structure of the space 1 to be measured, and the distribution thereof is such that the sampling is performed by sampling the entire internal region of the space 1 to be measured to obtain a representative sample, and for the space 1 to be measured having a structure in which a ceiling, a floor, etc. separate the space, the plurality of set sampling points should include the upper portion of the ceiling, the lower portion of the floor, the intermediate portion between the ceiling and the floor, and the individual sampling points inside the individual spaces, and the number of set sampling points of the entire internal region of the space 1 to be measured should be not less than three. The sampling can be performed by adopting the injectors with advanced numbers, the number of each injector has uniqueness and identifiability, and the information of the sample can be identified according to the number, including the corresponding set sampling point and sampling time. The volume of the injector is at least three times of the minimum sample injection volume of the trace gas analyzer, and the injector has good sealing performance, so that the sample is ensured not to be diluted or polluted. The sampling can be performed manually by using a syringe or automatically by using sampling equipment.
The intervals of the multiple samplings are equal and determined, preferably the reference T can be controlled according to the phase time m To determine the sampling interval time, the sampling interval time t s (in min) satisfies: t is t s <0.2T m 。
The obtained sample analyzes the concentration of the sample trace gas through the trace gas analyzer, preferably, before analyzing the concentration of the sample trace gas, the trace gas analyzer is debugged to have test conditions, the trace gas analyzer can be calibrated once by adopting at least three trace gas standard gases with different concentrations, in the use process, the trace gas standard gases can be used for checking the indication drift of the trace gas analyzer regularly, and if the indication drift exceeds 5 percent, the analysis result of the test sample is corrected according to the analysis indication values of the trace gas standard gases of the front and the back times so as to ensure that the accurate sample trace gas concentration is obtained.
In the sampling process, the diffusion condition of the trace gas in the space 1 to be measured can be judged according to the sample trace gas concentration of each set sampling point measured by analysis, and the sample data for formally calculating the free volume of the space 1 to be measured should be taken as the data of the sample meeting the condition of the mixing uniformity of the trace gas in the space 1 to be measured, so that in the sampling process, after the diffusion of the trace gas in the space 1 to be measured is confirmed for the first time to meet the condition of the mixing uniformity, the sample is required to be taken according to the sampling interval time t s And continuously sampling for at least ten times to prepare for formally calculating the free volume of the space 1 to be measured. Preferably, the mixing uniformity conditions for the diffusion of the tracer gas in the space 1 to be measured are: the deviation of the sample tracer gas concentration of each set sampling point from the average value of the sample tracer gas concentrations of all set sampling points is not more than 5%, i.e. the tracer gas is considered when the deviation of the sample tracer gas concentration of each set sampling point from the average value of the sample tracer gas concentrations of all set sampling points is within 5%The body is fully and uniformly diffused in the space 1 to be measured, and the measurement data of the sample obtained after the diffusion can be used for formally calculating the free volume of the space 1 to be measured, so that errors in calculation results of the free volume of the space 1 to be measured can be avoided due to uneven mixing of the trace gas in the space 1 to be measured.
Step four, establishing a trace gas average concentration increase curve according to trace gas concentrations and sampling time of all samples and obtaining trace gas average concentration in the space 1 to be measuredThe trace gas average concentration increase curve will have a short increase just before beginning and then entering the equilibrium stage, the increase stage time before entering the equilibrium stage being about the mixing time t mix Three times (1). Preferably, when the free volume calculation of the space 1 to be measured is performed by using the trace gas average concentration increase curve data, the data before the equilibrium stage is reached in the trace gas average concentration increase curve should be excluded to ensure the accuracy of the calculation result. The average concentration of the tracer gas in the space 1 to be measured +.>(unit is m 3 /m 3 ) Can be obtained from data of the equilibrium phase in the trace gas average concentration increase curve.
Step five, calculating the free volume V of the space 1 to be measured i The calculation formula is as follows:
in which the tracer gas is injected at a concentration C in Injection flow rate q in And injection time t in Average concentration of trace gas in space 1 to be measuredBackground concentration C of trace gas in space 1 to be measured 0 All have been determined and measured by the above steps, and the calculated empty space to be measuredFree volume V of space 1 i Is in units of m 3 。
Further, after the measurement calculation is completed, uncertainty analysis evaluation can be performed according to a method prescribed in a standard JJF 1059.1 "measurement uncertainty evaluation and representation". If the measurement calculation is performed accurately and effectively according to the above steps of the space free volume measurement method of the present embodiment, the free volume V of the space 1 to be measured is finally obtained i The measurement error of (2) can be controlled within 10%.
Therefore, according to the space free volume measuring method of the embodiment, quantitative tracer gas is injected into the space 1 to be measured, and then the average concentration of the tracer gas after diffusion and mixing in the space 1 to be measured is analyzed through sampling, so that the free volume of the space 1 to be measured can be obtained through calculation according to the concentration, flow and time of the tracer gas injection, the background concentration of the tracer gas in the space 1 to be measured and the average concentration of the tracer gas in the space 1 to be measured after the tracer gas is injected, the problems of high free volume measuring difficulty and poor precision caused by complex structure and more content of the space 1 to be measured can be solved, and particularly, the accurate measurement of the free volume of the space 1 to be measured with irregular shape, complex internal structure and complex ventilation pipeline can be realized, and the advantages of high accuracy, strong operability and good applicability are achieved.
In the embodiment, in the second step, the trace gas is injected into the space 1 to be measured in two modes of single-point injection of the return air pipeline and multi-point injection of the network pipeline. As shown in fig. 1 and 2, the mixing device 3 is configured inside a space 1 to be measured, a return air pipeline 4 communicated with the space 1 to be measured is arranged outside the space 1 to be measured, a return air fan 5 is arranged on the return air pipeline 4, and when the return air fan 5 is started, air in the space 1 to be measured can flow circularly through the return air pipeline 4, so that mixing can be accelerated.
Referring to fig. 1, in one embodiment, a trace gas may be injected into the space 1 to be measured by single point injection of the return air duct. The return air duct single point injection is achieved by connecting the outlet of the tracer gas source 2 to the return air duct 4 via a single injection duct 6. At this time, the trace gas is injected into the return air pipeline 4 at a single point, and the return air fan 5 is startedThe tracer gas is sent into the space 1 to be tested through air flow distribution and return air mixing of the return air pipeline 4, and is quickly and uniformly mixed in the space 1 to be tested under the combined action of the mixing device 3. Preferably, the outlet of the trace gas source 2 can be connected with the inlet of the injection pipeline 6 through the pressure reducing valve 7, the outlet of the injection pipeline 6 is connected with the return air pipeline 4, and the injection pipeline 6 is sequentially provided with the stop valve 8 and the flow controller 9. The tracer gas source 2, the pressure reducing valve 7 and the stop valve 8 are opened, and the tracer gas can be injected into the space 1 to be measured. The pressure of the tracer gas fed into the injection conduit 6 can be regulated by means of the pressure reducing valve 7 so that it meets the inlet pressure of the flow controller 9. The flow rate of the tracer gas fed into the space 1 to be measured can be controlled to a determined tracer gas injection flow rate q by a flow controller 9 in . During the test, the back-air blower 5 can be started, the mixing device 3 can be started, then the trace gas source 2 is started, the pressure reducing valve 7 is regulated to meet the inlet pressure of the flow controller 9, and finally the stop valve 8 is opened, the flow is controlled by the flow controller 9, and the trace gas is injected into the flow q with a determined flow rate in Injecting the mixture into the space 1 to be measured; after the tracer gas injection is completed, the stop valve 8, the pressure reducing valve 7 and the tracer gas source 2 are sequentially closed; during the process, the times at which the tracer gas starts and ends injection are recorded. Sampling may then begin.
Referring to fig. 2, in another embodiment, the trace gas may be injected into the space 1 to be measured by using a network pipeline multi-point injection method. The network pipeline multipoint injection mode is that a plurality of injection points are arranged in the space 1 to be tested, and the outlet of the trace gas source 2 is connected to the plurality of injection points through a plurality of injection pipelines 61 and 62. The injection points are distributed at different positions in the space 1 to be measured, so that the injected tracer gas can be directly distributed to different positions in the space 1 to be measured by the injection pipelines 61 and 62 and can be quickly and uniformly mixed in the space 1 to be measured under the combined action of the mixing device 3. At this time, the tracer gas is well diffused due to the multipoint dispersion injection, so that the return air blower 5 does not need to be turned on, but if the actual condition of the space 1 to be measured needs to further enhance the diffusion of the tracer gas, the return air blower 5 can also be turned on. Preferably, the outlet of the trace gas source 2 may be distributed through a pressure reducing valve 7, a shut-off valve 80 and a flow rate in sequenceThe device 10 is connected with inlets of a plurality of injection pipelines 61 and 62, the plurality of injection pipelines 61 and 62 are connected in parallel, outlets of the plurality of injection pipelines 61 and 62 are respectively connected to a plurality of injection points in the space 1 to be tested, and the plurality of injection pipelines 61 and 62 are respectively provided with stop valves 81 and 82 and flow controllers 91 and 92 in sequence. The tracer gas source 2, the pressure reducing valve 7 and the shut-off valves 80, 81, 82 are opened and the tracer gas can be injected into the space 1 to be measured. The pressure of the trace gas fed into the injection lines 61, 62 can be regulated by the pressure reducing valve 7 to meet the inlet pressure of the flow controllers 91, 92. The total flow rate of the tracer gas fed into the space 1 to be measured by the plurality of injection pipes 61, 62 can be controlled to a determined tracer gas injection flow rate q by the flow controllers 91, 92 in . The flow of the gas in the respective injection conduit 61, 62 can be controlled by means of shut-off valves 81, 82 for the purpose of distributing the tracer gas according to the tracer gas demand at each injection point. During the test, the mixing device 3 can be started first, and whether the return fan 5 is started or not is selected according to the actual situation, then the tracer gas source 2 is started, the pressure reducing valve 7 is regulated to meet the inlet pressure of the flow controllers 91 and 92, then the stop valves 81 and 82 are opened, finally the stop valve 80 is opened, the flow is controlled by the flow controllers 91 and 92, and the tracer gas is injected into the container at the determined flow q in Multi-point injection is carried out into the space 1 to be measured through the injection pipelines 61 and 62; after the tracer gas in the single injection pipeline is injected, closing a stop valve on the injection pipeline; after the complete injection of the trace gas, the stop valve 80, the pressure reducing valve 7 and the trace gas source 2 are sequentially closed; in the process, the beginning injection time of the trace gas and the ending injection time of each injection pipeline are recorded. Sampling may then begin.
In this embodiment, a high-precision flow controller 9, 91, 92 is used to quantitatively deliver the tracer gas from the tracer gas source 2 to the space 1 to be measured, the accuracy of the flow controller 9, 91, 92 should be within ±2%, and the tracer gas injection flow q is determined in The error from the actual injection flow should not exceed 2%. The timing of each stage in the test process adopts unified timing equipment, and the timing measurement error is controlled within +/-1%.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present invention, and these modifications and substitutions should also be considered as being within the scope of the present invention.
Claims (8)
1. A method for measuring the free volume of a space, comprising the following steps in sequence:
step one, enabling the pressure boundary of a space to be measured to be in a sealed state, and measuring the background concentration C of the tracer gas in the space to be measured 0 ；
Step two, according to the determined tracer gas injection concentration C in Injection flow rate q in And injection time t in Injecting trace gas into the space to be detected;
step three, a plurality of set sampling points in the space to be measured are determined according to the determined sampling interval time t s Continuously sampling for multiple times, analyzing the concentration of the tracer gas of the obtained sample, and determining that the diffusion of the tracer gas in the space to be tested meets the condition of mixing uniformity for the first time in the sampling process according to the sampling interval time t s Continuously sampling for at least ten times, wherein the mixing uniformity condition is that the deviation of the concentration of the sample tracer gas at each set sampling point relative to the average value of the concentration of the sample tracer gas at all set sampling points is not more than 5%;
step four, establishing a trace gas average concentration increase curve according to trace gas concentrations and sampling time of all samples and obtaining the trace gas average concentration in the space to be detected
Step five, calculating the free volume V of the space to be measured i The calculation formula is as follows:
2. a free space volume measurement according to claim 1The measuring method is characterized in that in the first step, the ventilation rate of the space to be measured is estimated to be A m Determining the phase time control reference as T m And satisfies the following: t (T) m <0.1/A m 。
3. The method of claim 2, wherein in the second step, the tracer gas injection time is determined to be t in And satisfies the following: t is t in <0.1T m The method comprises the steps of carrying out a first treatment on the surface of the Determination of tracer gas injection concentration C in Providing a trace gas concentration for the selected trace gas source; determining the tracer gas injection flow rate as q in And satisfies the following: q in ×C in ×t in ＝＝C t ×V m Wherein C is t For the target concentration of the trace gas in the space to be measured, V m And estimating the free volume of the space to be measured.
4. The method according to claim 2, wherein in the second step, when the tracer gas is injected into the space to be measured, the tracer gas is mixed in the space to be measured for a certain mixing time t by a mixing device provided in the space to be measured mix And the diffusion is uniform.
5. The method of measuring free volume in space according to claim 4, wherein the mixing time t mix The method meets the following conditions:
t mix <0.2T m 。
6. the method according to claim 2, wherein in the third step, the sampling interval time t s The method meets the following conditions: t is t s <0.2T m 。
7. A method of measuring free volume in a space according to any one of claims 1 to 6, wherein in step two, a return air duct is provided outside the space to be measured in communication with the space to be measured, and the outlet of the trace gas source is connected to the return air duct through a single injection duct.
8. A method of measuring free volume in space according to any one of claims 1 to 6, characterized in that in step two, a plurality of injection points are provided in the space to be measured, the outlet of the trace gas source being connected to a plurality of said injection points by a plurality of injection pipes.
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| CN114295300A (en) * | 2021-11-25 | 2022-04-08 | 中国核电工程有限公司 | System and method for measuring free volume and internal leakage of habitability area of nuclear power station main control room |
| CN114838879A (en) * | 2022-03-25 | 2022-08-02 | 中国辐射防护研究院 | Method for measuring internal leakage of gas of main control chamber of nuclear power station by using constant concentration method |
| CN117664264B (en) * | 2024-01-31 | 2024-05-10 | 南京九川科学技术有限公司 | Method for measuring volume of micro cavity |
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