CN110632213A - Method for detecting content of acetylene in liquid oxygen - Google Patents
Method for detecting content of acetylene in liquid oxygen Download PDFInfo
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- CN110632213A CN110632213A CN201911012520.3A CN201911012520A CN110632213A CN 110632213 A CN110632213 A CN 110632213A CN 201911012520 A CN201911012520 A CN 201911012520A CN 110632213 A CN110632213 A CN 110632213A
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- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 title claims abstract description 94
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000009833 condensation Methods 0.000 claims abstract description 44
- 230000005494 condensation Effects 0.000 claims abstract description 44
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 29
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 29
- 238000001514 detection method Methods 0.000 claims abstract description 26
- 239000007789 gas Substances 0.000 claims abstract description 21
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 20
- 230000008569 process Effects 0.000 claims abstract description 20
- 238000003303 reheating Methods 0.000 claims abstract description 13
- 238000004458 analytical method Methods 0.000 claims abstract description 10
- 238000000605 extraction Methods 0.000 claims abstract description 4
- 238000005070 sampling Methods 0.000 claims description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 13
- 239000001301 oxygen Substances 0.000 description 13
- 229910052760 oxygen Inorganic materials 0.000 description 13
- 239000012535 impurity Substances 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 9
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 8
- 238000009835 boiling Methods 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 239000012468 concentrated sample Substances 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000001294 propane Substances 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000002309 gasification Methods 0.000 description 2
- 239000012774 insulation material Substances 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 238000004587 chromatography analysis Methods 0.000 description 1
- 230000005686 electrostatic field Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/12—Preparation by evaporation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
- G01N2001/1031—Sampling from special places
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/12—Preparation by evaporation
- G01N2030/121—Preparation by evaporation cooling; cold traps
- G01N2030/122—Preparation by evaporation cooling; cold traps cryogenic focusing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/12—Preparation by evaporation
- G01N2030/126—Preparation by evaporation evaporating sample
Abstract
The invention discloses a method for detecting the content of acetylene in liquid oxygen, which is characterized by comprising the following steps: firstly, concentrating and extracting hydrocarbon in liquid oxygen; then introducing the extracted hydrocarbon into a chromatograph for detection and analysis; in the concentration and extraction process, liquid oxygen is contained by a flask, the flask is communicated to a condensing pipe, the liquid oxygen is naturally vaporized at ambient temperature and is discharged through the condensing pipe, and in the condensation process, the condensing pipe is placed in condensate to condense hydrocarbon; and after the liquid oxygen is evaporated, taking out the condenser pipe for reheating, and connecting the condenser pipe with a sampler to collect concentrated gas. The method for detecting the content of acetylene in liquid oxygen is convenient and fast to operate, can improve the detection limit of acetylene in liquid oxygen, is convenient to accurately analyze the content of acetylene in liquid oxygen, and has strong practicability and good application prospect.
Description
Technical Field
The invention belongs to the technical field of liquid oxygen detection, and particularly relates to a detection method for improving the detection limit of acetylene and facilitating detection of the content of acetylene in liquid oxygen.
Background
The cryogenic air separation method (hereinafter referred to as air separation) is the most important production mode of industrial oxygen and medical oxygen, acetylene in liquid oxygen of a main condensation evaporator of an air separation unit is the most dangerous substance in safety production, the content of the acetylene is strictly controlled, generally, the content of the acetylene in the liquid oxygen of the air separation unit is less than 0.1ppm (V/V), when the content is more than 0.1ppm, an alarm is required, and when the content exceeds 1ppm, a stop is required, otherwise, the explosion risk can occur. According to GB/T28125.1-2011 "determination of hazardous substances in air separation Process" part 1, determination of hydrocarbons requires: the detection limit of the gas chromatograph on acetylene is required to be less than 0.02ppmV/V (the detection limit refers to the minimum value of input quantity which can be exactly reacted by an instrument and is defined as the ratio of double noise to sensitivity), while the detection limit of the acetylene of a general type hydrogen flame gas chromatograph (hereinafter referred to as chromatograph) is higher than 0.1ppm (V/V), so that the acetylene content in sample gas needs to be indirectly increased to accurately analyze the acetylene content in liquid oxygen.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides the method for detecting the content of acetylene in liquid oxygen, which is convenient to operate, can improve the detection limit of acetylene in liquid oxygen and is convenient to accurately analyze the content of acetylene in liquid oxygen.
In order to achieve the purpose, the invention adopts the technical scheme that: the method for detecting the content of acetylene in liquid oxygen is characterized by comprising the following steps: firstly, concentrating and extracting hydrocarbon in liquid oxygen; then introducing the extracted hydrocarbon into a chromatograph for detection and analysis; in the concentration and extraction process, liquid oxygen is contained by a flask, the flask is communicated to a condensing pipe, the liquid oxygen is naturally vaporized at ambient temperature and is discharged through the condensing pipe, and in the condensation process, the condensing pipe is placed in condensate to condense hydrocarbon; and after the liquid oxygen is evaporated, taking out the condenser pipe for reheating, and connecting the condenser pipe with a sampler to collect concentrated gas.
In order to make the technical scheme more detailed and concrete, the invention also provides the following further preferable technical scheme to obtain satisfactory practical effect:
liquid oxygen is adopted as the condensate, and the condensation pipe is placed in a heat-preserving container filled with the liquid oxygen in the condensation process.
And after the liquid oxygen is evaporated, plugging the inlet end of the condensation pipe by using a plug, connecting the outlet end of the condensation pipe with the sampler, taking the condensation pipe out of the heat-insulating barrel, and putting the condensation pipe in running water for reheating.
The flask is provided with a wooden plug, one end of a flask draft tube penetrates through the wooden plug and is communicated into the flask, and the inlet end and the outlet end of the condensation pipe are both provided with a straight joint.
In the condensation process, the straight joint at the inlet end is connected with the flask draft tube, and the outlet end is emptied; in the sampling process, the plug is arranged on a straight joint arranged at the inlet end of the condensation pipe, and the straight joint at the outlet end is connected to the sampler through a sampler guide pipe.
The sampling device is characterized in that the sampling device flow guide pipe is provided with a stop valve capable of controlling connection and disconnection, and the stop valve is opened firstly in the sampling process and then the condensation pipe is taken out for reheating.
And after sampling is finished, closing the stop valve, and connecting the sampler to the chromatograph to open the stop valve again.
The sampler is a cylindrical structure, and a sampler inlet connected with a sampler guide pipe is arranged on the sampler.
And a pressure gauge is also arranged on the sampler.
Compared with the prior art, the invention has the following advantages: the method for detecting the content of acetylene in liquid oxygen is convenient and fast to operate, can improve the detection limit of acetylene in liquid oxygen, is convenient to accurately analyze the content of acetylene in liquid oxygen, and has a good application prospect.
Drawings
The contents of the drawings and the reference numerals in the drawings of the present specification will be briefly described as follows:
FIG. 1 is a schematic diagram of the detection system of the present invention.
FIG. 2 is a schematic diagram of the detection system of the present invention.
FIG. 3 is a schematic diagram of the detection system of the present invention.
FIG. 4 is a chromatograph analysis spectrum of a standard gas direct sampling method.
FIG. 5 is a chromatogram obtained by analysis by a chromatograph according to the concentration sampling method.
In the drawings, the reference numbers: 1. flask, 2, wooden plug, 3, flask honeycomb duct, 4, condenser, 5, heat-preserving container, 6, end cap, 7, stop valve, 8, sampler, 9, manometer, 10, through joint, 11, chromatograph.
Detailed Description
The following description of the embodiments of the present invention will be made in detail with reference to the accompanying drawings.
The method for detecting the content of acetylene in liquid oxygen comprises the steps of firstly, concentrating and extracting hydrocarbon in the liquid oxygen; and then introducing the extracted hydrocarbon into a chromatograph for detection and analysis. In the concentration and extraction process, liquid oxygen is contained in a flask 1, the flask 1 is communicated with a condensing tube 4, the liquid oxygen is naturally vaporized at ambient temperature and is discharged through the condensing tube 4, and the condensing tube 4 is placed in condensate liquid to condense hydrocarbon in the condensation process; after the liquid oxygen is evaporated, the condensing tube 4 is taken out for reheating, and the condensing tube 4 is connected through a sampler 8 to collect the concentrated gas.
In the invention, liquid oxygen is used as condensate, and the condensing tube is placed in the heat-insulating barrel 5 filled with the liquid oxygen in the condensing process. After the liquid oxygen is evaporated, the inlet end of the condenser tube 4 is plugged by a plug 6, the outlet end of the condenser tube 4 is connected with a sampler 8, and the condenser tube 4 is taken out from the heat-insulating barrel 5 and placed in running water for reheating. A wood plug 2 is arranged on the flask 1, one end of a flask draft tube 3 penetrates through the wood plug 2 and is communicated into the flask 1, and the inlet end and the outlet end of the condensation pipe are respectively provided with a straight joint 10. A straight joint 10 at the inlet end in the condensation process is connected with a flask draft tube 3, and the outlet end is emptied; in the sampling process, the plug 6 is arranged on a straight joint 10 arranged at the inlet end of the condensation pipe, and the straight joint 10 at the outlet end is connected to a sampler 8 through a sampler guide pipe.
In the invention, the stop valve 7 capable of controlling conduction and stop is arranged on the flow guide pipe of the sampler, and the stop valve 7 is opened first and then the condenser pipe is taken out for reheating in the sampling process. After completion of sampling, the stop valve 7 is closed, and the stop valve 7 is opened again by connecting the sampler 8 to the chromatograph 11.
The system for detecting the content of acetylene in liquid oxygen comprises a flask 1 for containing the liquid oxygen, a condenser pipe 4, a heat preservation barrel 5 for condensing hydrocarbon in the liquid oxygen, wherein the flask 1 is communicated with the condenser pipe 4, the gasified oxygen at normal temperature is discharged through the condenser pipe 4, and the condenser pipe 4 is arranged in the heat preservation barrel 5 for containing the liquid oxygen; after the liquid oxygen is evaporated, a plug 6 is arranged at the inlet end of a condensation pipe 4, the outlet end of the condensation pipe 4 is connected with a sampler 8 for collecting concentrated gas, and the condensation pipe 4 is taken out from a heat-insulating barrel 5 and placed in running water for reheating; the detection system further comprises a chromatograph 11 connected to the sampler 8, and the acetylene content is analyzed in the chromatograph 11.
In the invention, as shown in figures 1 and 2, a wooden plug 2 is arranged on a flask 1, one end of a flask draft tube 3 penetrates through the wooden plug 2 and is communicated into the flask 1, and the other end is connected to a condensation pipe 4 through a straight-through joint 10. The inlet end and the outlet end of the condensation pipe 4 are both provided with a through connector 10, the through connector at the inlet end is detachably connected with the flask draft tube 3, and the through connector 10 at the outlet end is connected to the sampler 8 through a sampler draft tube.
The condenser 4 is arranged in the heat-insulating barrel 5 in the condensation process, hydrocarbon in oxygen is condensed through liquid oxygen, the oxygen cannot be condensed in the metal condenser pipe under the action of airflow generated by liquid oxygen gasification, and the vaporized oxygen is discharged through the metal condenser pipe. As shown in table 1, the boiling point of oxygen is-182.9 ℃, which is lower than that of other impurities, and the liquid oxygen is evaporated and vaporized by an external cold source (liquid oxygen), and the high boiling impurities such as acetylene can be condensed and collected. After the liquid oxygen is evaporated, the flask 1 is taken down, the plug 6 is installed on the straight joint 10 at the inlet end of the condensation pipe 4, the straight joint 10 at the outlet end is connected to the sampler 8 through the sampler guide pipe, the stop valve 7 is opened, the condensation pipe 4 is taken out from the heat-insulating barrel 5 and placed in flowing water for reheating, the condensed hydrocarbons such as acetylene and the like are gasified again and collected into the sampler 8, and then the concentrated sample with the original concentration of thousands of times can be obtained, and then the concentrated sample is sent into the chromatograph 11 for detection, which is equivalent to that the concentration of impurities such as acetylene and the like is improved by thousands of times, and the detection limit and the accuracy are greatly improved.
In the present invention, the plug 6 is mounted on a through joint 10 provided at the inlet end of the condensation duct. The straight-through structure adopts a double-clamping sleeve joint to be in transition connection with the condensation pipe and the flow guide pipe, is convenient to connect and disassemble and is convenient to connect the plug. The sampling device guide pipe is provided with a stop valve 7 which can control the gas in the pipeline to be conducted and stopped, so that the sampling device is convenient to collect and sample and control the gas to be conducted to the chromatograph 11. The stop valve 7 can be a stainless steel needle valve.
In the invention, the sampler 8 is a cylindrical structure, and the sampler 8 is provided with a sampler inlet connected with a sampler guide pipe. The sampler 8 is also provided with a pressure gauge 9. The pressure and temperature of the sampler are read by a high-precision pressure gauge and are simultaneously measured, and then the pressure and temperature are sent to a chromatograph 11 to be analyzed for the content of acetylene and other hydrocarbon impurities. The sampler 8 is preferably made of stainless steel, the volume of the sampler is controlled to be between 250 ml and 500 ml, and the sampler is also provided with a sample gas inlet and a pressure gauge connector.
In the invention, the condenser tube 4 is made of a copper tube, and the inlet end and the outlet end of the condenser tube are both arranged at the upper end. The snakelike condenser pipe is soaked in liquid oxygen during condensation, and red copper (pure copper is preferably selected as the material, because the red copper has good heat conductivity coefficient and is 386.4W/(m.K), the plasticity and cold pressing processability are good, the cold quantity of the liquid oxygen can be better transferred, so that a constant low-temperature space is formed in the condenser pipe, the outer diameter of a copper pipe is 6 mm, the straight joint 10 used for the inlet and the outlet of the metal condenser pipe is connected by adopting a stainless steel double-ferrule with the diameter changing of 6 mm-3 mm, in order to ensure that a good condensation effect is obtained, the copper pipe with the total length not less than 2 m is adopted for manufacturing, and the wound diameter is not less than 4 cm.
The content of impurities in the liquid oxygen of the air separation plant includes hydrocarbons such as methane, ethane, ethylene, propane, etc. in addition to acetylene, and the boiling points of the impurities such as oxygen and acetylene at one atmospheric pressure are different, as shown in table 1 below.
TABLE 1 temperatures of hydrocarbons and liquid oxygen
The boiling point of oxygen is-182.9 deg.C, which is lower than that of other impurities, and the liquid oxygen is evaporated and vaporized by external cold source (liquid oxygen) while the high boiling point impurities such as acetylene can be condensed and collected.
The invention relates to a detection method for detecting the content of acetylene in liquid oxygen, which is characterized in that a flask 1 is used for accurately containing a certain amount of liquid oxygen, a wooden plug 2 inserted with a flask draft tube 3 is covered, and then the liquid oxygen is naturally vaporized at the ambient temperature. The vaporized oxygen is discharged through the metal condenser tube 4 (the metal condenser tube is placed in the heat-insulating barrel 5, and the heat-insulating barrel 5 contains liquid oxygen, which is equivalent to the metal condenser tube soaked in the liquid oxygen). Due to the action of the air flow generated by the gasification of the liquid oxygen, the oxygen cannot be condensed in the metal condenser pipe 4; the condensation points of the hydrocarbons are far higher than that of the liquid oxygen, and the hydrocarbons are easy to condense in the metal condenser pipe. After the liquid oxygen in the flask 1 is evaporated, one side of the condensation pipe 4 is blocked by a plug 6, the other side of the condensation pipe is connected with a cylindrical sampler 8, then a stop valve 7 is opened, and the condensation pipe 4 is taken out of the liquid oxygen. The condenser tube 4 is fully reheated to normal temperature in running water, and hydrocarbons such as acetylene and the like condensed are regasified again to fill the metal condenser tube, the sampler and the pipeline. And after the condenser pipe is completely reheated, the stop valve 7 is closed, the pressure of the sampler 8 is read through a high-precision pressure gauge, the temperature of the sampler is measured at the same time, and the sampler is sent to a chromatograph 11 to analyze the content of acetylene and other hydrocarbon impurities.
According to the detection principle of the chromatograph, after entering the chromatograph, the concentrated sample gas is separated from hydrocarbons such as oxygen, methane, ethane, ethylene, acetylene, propane and the like through a chromatographic column and sequentially enters a hydrogen flame detector. In the detector, each hydrocarbon is burnt by the hydrogen flame and ionized into positive and negative ions, and micro-current is formed. The microcurrents are collected under the action of an electrostatic field, which is proportional to the concentration of the individual hydrocarbons. And amplifying, processing and displaying and converting the micro-current to obtain the final concentration of each hydrocarbon.
Standard gas concentration test, the purpose of which was to verify the efficiency of the freeze concentration process. Fig. 4 and 5 are chromatographic analysis charts of the standard gas direct sampling method and the concentration sampling method. The results are shown in Table 2 below (60 liters of standard gas was introduced, the pressure after vaporization by the sampler was 0.331325MPa gauge pressure, and the temperature of the sampler was 15 ℃ C.).
TABLE 2 data sheet for direct sampling and concentrated sampling analysis of standard gas
Calculating theoretical concentration multiple:
n-theoretical concentration ratio M-standard gas volume (standard state), L;
m-volume of the sampler, the coiled pipe and the pipeline, 0.272L; p is absolute pressure after reheating of the sampler, MPa;
P0-standard atmospheric pressure, MPa; t-standard state temperature, 273.15K;
T0-actual temperature of the sampler, K;
and (3) measuring and calculating the actual concentration multiple:
a-direct sampling analysis of the values; b, concentrating the sampling analysis value;
w is the actual concentration ratio;
and (3) actual concentration efficiency measurement:
z-actual concentration efficiency
According to the actual concentration efficiency measurement of each hydrocarbon in the standard gas, the highest actual concentration efficiency is 93.88% of propane, 87.98% of acetylene and 85.63% of ethane, and the difference is in direct proportion to the boiling point difference between each hydrocarbon and liquid oxygen, and the difference between the boiling points of acetylene and liquid oxygen is between propane and ethane. Therefore, the efficiency must be greater than 85.63% and less than 93.88%, with a conservative estimate of 85.0%.
Actual sample analysis and calculation
Actual concentration factor
x-measuring the volume of liquid oxygen, L; 804-1 liter of liquid oxygen is converted into gas oxygen volume under the standard state;
0.85-concentration efficiency
Calculation of acetylene content in samples
Actual C-acetylene content, ppm V/V; cn-acetylene content in ppm V/V of concentrated sample
Safety precautions in the detection process: the anti-freezing protective article should be worn when taking liquid oxygen. The flask from which the liquid oxygen was taken should be kept dry and clean. A small amount of liquid oxygen was first measured and the flask was cooled, and sampling could begin. When liquid oxygen begins to evaporate in the flask, the liquid oxygen is in a large evaporation amount due to a large difference with the ambient temperature, and the liquid oxygen is easy to generate overpressure to bring danger. The flask should be wrapped with a layer of insulation material, and the amount of liquid oxygen evaporated will determine whether the insulation material needs to be removed. The whole operation process of the concentration method is slow and accurate.
The concentration method has the advantages of simple structure, convenient operation, low cost, high concentration efficiency and good repeatability of measurement results, and when 1 liter of liquid oxygen is taken for evaporation, the acetylene content can be concentrated to more than 1000 times, the detection limit of acetylene in the liquid oxygen is reduced by 1000 times, so that a general hydrogen flame gas chromatograph can meet the requirement of national standard on the detection limit of acetylene.
The method for detecting the content of acetylene in liquid oxygen is convenient and fast to operate, can improve the detection limit of acetylene in liquid oxygen, is convenient to accurately analyze the content of acetylene in liquid oxygen, and has strong practicability and good application prospect.
The invention has been described above with reference to the accompanying drawings, but the invention is not limited to the above-described embodiments, and it is within the scope of the invention to use various insubstantial modifications of the inventive concept and solutions or to apply them directly to other applications.
Claims (9)
1. A method for detecting the content of acetylene in liquid oxygen is characterized by comprising the following steps: firstly, concentrating and extracting hydrocarbon in liquid oxygen; then introducing the extracted hydrocarbon into a chromatograph for detection and analysis; in the concentration and extraction process, liquid oxygen is contained by a flask, the flask is communicated to a condensing pipe, the liquid oxygen is naturally vaporized at ambient temperature and is discharged through the condensing pipe, and in the condensation process, the condensing pipe is placed in condensate to condense hydrocarbon; and after the liquid oxygen is evaporated, taking out the condenser pipe for reheating, and connecting the condenser pipe with a sampler to collect concentrated gas.
2. The method for detecting the content of acetylene in liquid oxygen according to claim 1, wherein the method comprises the following steps: liquid oxygen is adopted as the condensate, and the condensation pipe is placed in a heat-preserving container filled with the liquid oxygen in the condensation process.
3. The method for detecting the content of acetylene in liquid oxygen as claimed in claim 2, wherein: and after the liquid oxygen is evaporated, plugging the inlet end of the condensation pipe by using a plug, connecting the outlet end of the condensation pipe with the sampler, taking the condensation pipe out of the heat-insulating barrel, and putting the condensation pipe in running water for reheating.
4. The method for detecting the content of acetylene in liquid oxygen as claimed in claim 3, wherein: the flask is provided with a wooden plug, one end of a flask draft tube penetrates through the wooden plug and is communicated into the flask, and the inlet end and the outlet end of the condensation pipe are both provided with a straight joint.
5. The method for detecting the content of acetylene in liquid oxygen as claimed in claim 4, wherein: in the condensation process, the straight joint at the inlet end is connected with the flask draft tube, and the outlet end is emptied; in the sampling process, the plug is arranged on a straight joint arranged at the inlet end of the condensation pipe, and the straight joint at the outlet end is connected to the sampler through a sampler guide pipe.
6. The method for detecting the content of acetylene in liquid oxygen as claimed in claim 5, wherein: the sampling device is characterized in that the sampling device flow guide pipe is provided with a stop valve capable of controlling connection and disconnection, and the stop valve is opened firstly in the sampling process and then the condensation pipe is taken out for reheating.
7. The method for detecting the content of acetylene in liquid oxygen as claimed in claim 6, wherein: and after sampling is finished, closing the stop valve, and connecting the sampler to the chromatograph to open the stop valve again.
8. The method for detecting the acetylene content in liquid oxygen according to any one of claims 1 to 7, characterized in that: the sampler is a cylindrical structure, and a sampler inlet connected with a sampler guide pipe is arranged on the sampler.
9. The method for detecting the content of acetylene in liquid oxygen as claimed in claim 8, wherein: and a pressure gauge is also arranged on the sampler.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112524475A (en) * | 2020-12-24 | 2021-03-19 | 南京佰君维科技有限公司 | Accuse of regularly detecting acetylene flows hydraulic pressure holding vessel device |
Citations (2)
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| CN112524475A (en) * | 2020-12-24 | 2021-03-19 | 南京佰君维科技有限公司 | Accuse of regularly detecting acetylene flows hydraulic pressure holding vessel device |
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