CN111122800A - Low-concentration gas standard sample preparation device and method - Google Patents
Low-concentration gas standard sample preparation device and method Download PDFInfo
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- CN111122800A CN111122800A CN202010182661.6A CN202010182661A CN111122800A CN 111122800 A CN111122800 A CN 111122800A CN 202010182661 A CN202010182661 A CN 202010182661A CN 111122800 A CN111122800 A CN 111122800A
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
Abstract
The invention discloses a low-concentration gas standard sample preparation device and a method, wherein the device comprises a temperature control device, a six-way valve, a quantitative pipe, a gas pressure regulating device and a sample bottle, wherein six inlets and outlets of the six-way valve are connected with pipelines, a first port is connected with the sample bottle through a pressure regulating pipeline, a second port is connected with one end of the quantitative pipe, a fifth port is connected with the other end of the quantitative pipe, a third port is a target gas inlet and is connected with a target gas cylinder, a fourth port is a target gas outlet, and a sixth port is a balance gas inlet and is connected with a balance gas tank; a pressure regulating device is arranged on the pressure regulating pipeline connected with the first port; the quantitative pipe and the six-way valve are detachably connected; the six-way valve, the quantitative pipe and the pipeline between the six-way valve and the quantitative pipe are all arranged in the temperature control device; the both ends of sample bottle are provided with the ooff valve respectively: the device and the method have the advantages of simple and convenient operation, high speed, good preparation repeatability and capability of improving the working efficiency.
Description
Technical Field
The invention discloses a device and a method for preparing a low-concentration gas standard sample, in particular relates to a device and a method for preparing single-component mixed gas, and belongs to the technical field of preparation of gas standard substances.
Background
For the preparation of gas standards, it is common to weigh pure gas into a storage cylinder, as determined by weighing the mass of pure gas before and after addition, the difference between the two weighings being the net added mass. The gas standard substance is prepared by adopting a weighing method, the principle of the weighing method is that certain component gas with known concentration is transferred into a gas cylinder, the mass of the gas cylinder before and after the component is transferred is respectively weighed, the mass of the component gas added into the gas cylinder is determined according to the weighing difference, and the concentration of each component can be calculated according to the mass and the molar mass of each component. The mass fraction of each component in the mixed gas is the ratio of the mass of that component to the sum of the masses of all the components. When the concentration of a component in the mixed gas is expressed in terms of mole fraction, the concentration of each component in the mixed gas is the ratio of the amount of the substance of that component (moles) to the amount of the substance of all the components (total moles).
The influence of the balance weighing can be reduced to an acceptable range only when the preparation is required to obtain good preparation effect under the influence of the minimum resolution of a 10kg balance, generally 10mg, so that the minimum weighing mass of the weighing gas is more than 10g, and the dilution times during preparation by a limited weighing method are generally not more than 100 times; to obtain a relatively low concentration, multiple dilutions are required to achieve this.
For example, 1 mu mol/mol of nitrogen isobutene gas standard substance is prepared, a gas cylinder is usually used for the minimum 2L, the filling device pressure is 9MPa, and at 1 standard atmospheric pressure and 20 ℃, isobutene purity gas (99.999%) is weighed to be 0.0004198g in mass, so that at least 3-4 times of dilution is needed to prepare 1 mu mol/mol of nitrogen isobutene gas standard substance.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the device and the method for preparing the low-concentration gas standard sample, which are simple and convenient to operate, quick, good in preparation reproducibility and capable of improving the working efficiency.
The invention is realized by the following technical scheme:
a low-concentration gas standard sample preparation device comprises a temperature control device, a six-way valve, a quantitative pipe, a gas pressure regulating device and a sample bottle, wherein six inlets and outlets of the six-way valve are connected with pipelines, a first port is connected with the sample bottle through a pressure regulating pipeline, a second port is connected with one end of the quantitative pipe, a fifth port is connected with the other end of the quantitative pipe, a third port is a target gas inlet and connected with a target gas bottle, a fourth port is a target gas outlet, and a sixth port is a balance gas inlet and connected with a balance gas tank;
a pressure regulating device is arranged on the pressure regulating pipeline connected with the first port;
the quantitative pipe and the six-way valve are detachably connected; the six-way valve, the quantitative pipe and the pipeline between the six-way valve and the quantitative pipe are all arranged in the temperature control device;
the both ends of sample bottle are provided with the ooff valve respectively: the first switch valve is connected with the pressure regulating pipeline. And (4) replacing the air in the sample bottle by balance gas, and closing the second switch valve after replacement is finished.
The temperature control device is a digital temperature control device, and the gas pressure regulating device comprises a display device.
The dosing tube includes a plurality of different capacity specifications.
The six-way valve comprises a closed state and an open state, wherein in the closed state, the second port is communicated with the third port, the first port is communicated with the sixth port, and the fourth port is communicated with the fifth port; under the open state, No. two mouths and No. one mouth intercommunication, No. three mouths and No. four mouths intercommunication, No. five mouths and No. six mouths intercommunication.
A method of preparing a low concentration gas standard sample using the apparatus, comprising the steps of:
1) setting the temperature in the temperature control device;
2) enabling the six-way valve to be in a closed state, opening a first switch valve of the sample bottle, opening a valve of the balance gas, adjusting the flow rate of the pressure regulating device, enabling the balance gas to sequentially pass through a sixth port → a first port → the pressure regulating device → the first switch valve, enter the sample bottle and flow out of a second switch valve, and enabling the balance gas to fully convert air in the sample bottle;
3) closing the second switch valve;
4) opening a target gas bottle, enabling the target gas to enter a third port of the six-way valve, enabling the target gas to enter the quantitative pipe through a second port, enabling the quantitative pipe to be filled with the target gas, and closing the target gas bottle;
5) the six-way valve is switched to be in an open state, the first switch valve of the sample bottle is opened, the valve of the balance gas is opened, the balance gas sequentially passes through the six-way port → the five-way port → the quantitative tube → the two-way port → the first port → the pressure regulating device → the first switch valve to enter the sample bottle, the gas flow of the balance gas is controlled by regulating the pressure regulating device, and when the pressure in the sample bottle reaches the required pressure, the first switch valve is closed, so that the preparation of the standard sample is completed.
The temperature in the temperature control device is determined according to the temperature of the room temperature during preparation, the temperature difference between the set temperature and the room temperature is not more than +/-1 ℃, and the liquefaction condition of the inner wall of the quantitative pipe in the adsorption and filling process is prevented.
Whether the quantitative pipe is filled with the target gas or not is judged by the following method:
and (3) placing a pipeline of a fourth port of the six-way valve, namely a target gas outlet, below a container filled with water, and judging that the target gas is filled in the quantitative pipe when uniform bubbling is observed.
Compared with the prior art, the invention has the following beneficial effects:
in the traditional preparation method, a balance with large measuring range and low precision is required to be used for weighing the gas cylinder, and uncertainty in the weighing process can be repeatedly introduced by multi-stage dilution; the mixed gas standard substance is prepared by adopting the method, the preparation steps can be completed in one step, and the working efficiency is improved; and the uncertainty introduced in the preparation process is reduced by one order of magnitude compared with the traditional preparation method; the quantitative tube method reduces the preparation steps and the usage amount of raw materials, and improves the preparation efficiency of the mixed gas standard substance; the cost of the preparation equipment of the gas standard substance is reduced.
Drawings
FIG. 1 is a schematic diagram of the construction and gas flow of the device with the six-way valve closed;
fig. 2 is a schematic diagram of the structure and gas flow of the device when the six-way valve is closed.
FIG. 3 is a schematic view of a temperature control device.
In the figure 1: temperature control device, 2: a six-way valve; 3: quantitative tube, 4: pressure regulating device, 5: sample bottle, 6: pressure regulating pipeline, 8: balance gas tank, 9: first on-off valve, 10: second switching valve, 11: temperature control box, 12: heating sheet, 13: fan, 14: temperature sensor, 15: vent, 16: heating circuit, 21: first port, 22: second port, 23: third port, 24: number four port, 25: opening five, 26: and a sixth opening.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the scope of the present invention is not limited to these examples, and all changes or equivalent substitutions that do not depart from the spirit of the present invention are intended to be included within the scope of the present invention.
A low-concentration gas standard sample preparation device comprises a temperature control device 1, a six-way valve 2, a quantitative tube 3, a pressure regulating device 4 and a sample bottle 5, wherein six inlets and outlets of the six-way valve 2 are connected with pipelines, a first port 21 is connected with the sample bottle 5 through a pressure regulating pipeline 6, a second port 22 is connected with an inlet and an outlet at one end of the quantitative tube 3, a fifth port 25 is connected with an inlet and an outlet at the other end of the quantitative tube 3, a third port 23 is a target gas inlet and is connected with a target gas bottle, a fourth port 24 is a target gas outlet, a sixth port 26 is a balance gas inlet and is connected with a balance gas tank 8; the balance gas is nitrogen, and the target gas is isobutene.
A pressure regulating device 4 is arranged on the pressure regulating pipeline 6 connected with the first port;
the quantitative pipe 3 and the six-way valve 2 are detachably connected.
The six-way valve 2, the quantitative pipe 3 and the pipeline between the two are all arranged in the temperature control device 1;
the two ends of the sample bottle 5 are respectively provided with a switch valve: the first switch valve 9 is connected with the pressure regulating pipeline 6, and the second switch valve 10 is used for replacing air in the sample bottle by balance gas, and after replacement is finished, the valve 10 is closed.
The temperature control device 1 is a digital temperature control device, and the pressure regulating device 4 comprises a display device.
Temperature regulating device 1 includes accuse temperature box 11, be provided with heating plate 12, fan 13 and temperature sensor 14 in the accuse temperature box, be provided with ventilation hole 15 on the tank wall of accuse temperature box 11, heating plate 12 is connected with heating circuit 16, fan 13 connects fan circuit, fan 13 sets up in accuse temperature box 11 one side, ventilation hole 15 sets up in the offside of fan. The six-way valve 2, the quantitative pipe 3 and the pipeline between the two are all arranged in the temperature control box 11.
The heating plates 12 include a plurality of groups distributed at different positions of the temperature control box 11.
The temperature control device 1 automatically samples and immediately monitors the temperature of the temperature control area through the temperature sensor, and controls the starting and closing of a fan circuit switch and a heating circuit when the temperature of the temperature control area (namely the temperature control box) is higher or lower than a control set value.
In the actual preparation process, the target gas or the balance gas is mostly arranged in the gas cylinder and exists in a liquid state, liquid drops can be generated on a conveying pipeline or a quantitative pipe in the liquid gas gasification process, the accuracy of prepared standard gas is influenced, and the temperature control device heats the gas and can overcome the problem.
The temperature control device is used for heating the gas in the pipeline, so that a small amount of residual gas adsorbed on the inner wall of the pipeline or the quantitative pipe can be driven, and the purity of the prepared standard gas is ensured.
When the temperature control area needs to be cooled, the fan is started to replace the gas in the temperature control box, so that the temperature is reduced.
The pressure regulating device is an electronic pressure regulating valve arranged on the pressure regulating pipeline, the opening degree of an opening and closing part in the valve body is controlled by the electronic pressure regulating valve to regulate the flow of a medium, the pressure of the medium is reduced, and meanwhile, the opening degree of the opening and closing part is regulated under the action of the pressure behind the valve, so that the pressure behind the valve is kept within a certain range.
The dosing tube 3 comprises a plurality of different capacity specifications, the dosing tube is made of 1/16 inch (1/16 inch =1.5875 mm) stainless steel tube, and the size of the used capacity specification depends on the length of the used stainless steel tube; typically 1mL, 2mL, 5mL, 10 mL.
The six-way valve 2 comprises a closed state and an open state, wherein in the closed state, the second port 22 is communicated with the third port 23, the first port 21 is communicated with the sixth port 26, and the fourth port 24 is communicated with the fifth port 25; in the open state, the second port 22 is communicated with the first port 21, the third port 23 is communicated with the fourth port 24, and the fifth port 25 is communicated with the sixth port 26.
A method of preparing a low concentration gas standard sample using the apparatus, comprising the steps of:
1) setting the temperature in the temperature control device;
2) enabling the six-way valve to be in a closed state, opening a first switch valve of the sample bottle, opening a valve of the balance gas, adjusting the flow rate of the pressure regulating device, enabling the balance gas to sequentially pass through a sixth port → a first port → the pressure regulating device → the first switch valve 9 of the six-way valve, enter the sample bottle and flow out of a second switch valve 10, and enabling the balance gas to fully convert air in the sample bottle;
3) closing the second on-off valve 10;
4) opening a target gas bottle, enabling the target gas to enter a third port of the six-way valve, enabling the target gas to enter the quantitative pipe through a second port, enabling the quantitative pipe to be filled with the target gas, and closing the target gas bottle;
5) the six-way valve is switched to be in an open state, the first switch valve of the sample bottle is opened, the valve of the balance gas is opened, the balance gas sequentially passes through the six-way port → the five-way port → the quantitative tube → the two-way port → the first port → the pressure regulating device → the first switch valve 9 to enter the sample bottle, the gas flow of the balance gas is controlled by regulating the pressure regulating device, and when the pressure in the sample bottle reaches the required pressure, the first switch valve 9 is closed, so that the preparation of the standard sample is completed.
The temperature in the temperature control device is determined according to the temperature of the room temperature during preparation, the temperature difference between the set temperature and the room temperature is not more than +/-1 ℃, and the liquefaction condition of the inner wall of the quantitative pipe in the filling process is mainly prevented.
Whether the quantitative pipe is filled with the target gas or not is judged by the following method:
and (3) placing a pipeline of a fourth port of the six-way valve, namely a target gas outlet, below a container filled with water, and judging that the target gas is filled in the quantitative pipe when uniform bubbling is observed.
Example 1
To prepare: 1umol/mol, isobutene in nitrogen for example,
1. ambient temperature: (25 ± 2) ° c, packaging container: 0.5L aluminum alloy gas cylinder, choose the ration pipe of 1mL, according to the formula:
the mass of isobutene in a 1mL quantitative tube can be calculated to be 0.00002467 g; (molar mass: 4.39701E-07 mol).
To produce 1umol/mol of isobutene in nitrogen, a molar mass of nitrogen of about: 0.4397mol, (i.e., 12.3175g of nitrogen).
The pressure of nitrogen to be filled into the theoretical tank is obtained by the transformation of the formula (1)
Table 1 contents represented by symbols in the formulas
2. The procedures of steps 1) to 5) were repeated, and experimental data for standard sample preparation are shown in Table 2,
TABLE 2
Table 2 shows that the accuracy of the prepared standard gas is high by transferring a trace amount of target gas to the target gas cylinder through the quantitative tube and controlling the pressure of the added balance gas, and the prepared consistency is within 0.2%, which indicates that the pressure of the added gas is transferred and controlled through the quantitative tube. The concentration of trace gas can be well prepared, the preparation steps are reduced, and the operation efficiency is improved.
The method adopts detachable quantitative pipes with different capacities, a quantitative pressure regulating device and a six-way valve to switch a purging mode, and can realize the following steps: 1) the mass of the trace gas is measured by adopting the volume of a normal-pressure quantitative pipe; 2) the gas quality in the quantitative pipe is controlled by adjusting the temperature of the temperature control area, and the gas quality in the quantitative pipe can be adjusted by about 10%; 3) the flow direction of the gas is changed through the switching of the six-way valve, and the gas of the target component is blown into the storage gas cylinder; 4) reducing the preparation steps of the low-concentration gas standard substance; 5) gases of known concentration can be diluted up to 10 ten thousand times.
The present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. The low-concentration gas standard sample preparation device is characterized by comprising a temperature control device (1), a six-way valve (2), a quantitative tube (3), a pressure regulating device (4) and sample bottles (5), wherein six inlets and outlets of the six-way valve (2) are connected with pipelines, a first port (21) is connected with the sample bottles (5) through a pressure regulating pipeline (6), a second port (22) is connected with an inlet and an outlet at one end of the quantitative tube (3), a fifth port (25) is connected with an inlet and an outlet at the other end of the quantitative tube (3), a third port (23) is a target gas inlet and is connected with target gas bottles, a fourth port (24) is a target gas outlet, a sixth port (26) is a balance gas inlet and is connected with balance gas tanks (8);
a pressure regulating device (4) is arranged on the pressure regulating pipeline (6) connected with the first port;
the quantitative pipe (3) and the six-way valve (2) are detachably connected;
the six-way valve (2), the quantitative pipe (3) and a pipeline between the six-way valve and the quantitative pipe are arranged in the temperature control device (1);
the two ends of the sample bottle (5) are respectively provided with a switch valve: the first switch valve (9) and the second switch valve (10), the first switch valve (9) is connected with the pressure regulating pipeline (6).
2. The low-concentration gas standard sample preparation device according to claim 1, wherein the temperature control device (1) is a digital temperature control device, and the pressure regulating device (4) comprises a display device.
3. The low-concentration gas standard sample preparation device according to claim 1, wherein the quantitative tube (3) is a stainless steel tube comprising a plurality of different volume specifications.
4. The low-concentration gas standard sample preparation device according to claim 1, wherein the six-way valve (2) comprises a closed state and an open state, in the closed state, the second port (22) is communicated with the third port (23), the first port (21) is communicated with the sixth port (26), and the fourth port (24) is communicated with the fifth port (25); in an open state, the second port (22) is communicated with the first port (21), the third port (23) is communicated with the fourth port (24), and the fifth port (25) is communicated with the sixth port (26).
5. A method for preparing a low-concentration gas standard sample by using the apparatus of claims 1 to 4, comprising the steps of:
1) setting the temperature in the temperature control device;
2) enabling the six-way valve to be in a closed state, opening a first switch valve of the sample bottle, opening a valve of the balance gas, adjusting the flow rate of the pressure regulating device, enabling the balance gas to sequentially pass through a sixth port → a first port → the pressure regulating device → the first switch valve, enter the sample bottle and flow out of a second switch valve, and enabling the balance gas to fully convert air in the sample bottle;
3) closing the second switch valve;
4) opening a target gas bottle, enabling the target gas to enter a third port of the six-way valve, enabling the target gas to enter the quantitative pipe through a second port, enabling the quantitative pipe to be filled with the target gas, and closing the target gas bottle;
5) the six-way valve is switched to be in an open state, the first switch valve of the sample bottle is opened, the valve of the balance gas is opened, the balance gas sequentially passes through the six-way port → the five-way port → the quantitative tube → the two-way port → the first port → the pressure regulating device → the first switch valve to enter the sample bottle, the gas flow of the balance gas is controlled by regulating the pressure regulating device, and when the pressure in the sample bottle reaches the required pressure, the first switch valve is closed, so that the preparation of the standard sample is completed.
6. The method for preparing a low-concentration gas standard sample according to claim 5, wherein whether the quantitative tube is filled with the target gas is determined by: and (3) placing a pipeline of a fourth port of the six-way valve, namely a target gas outlet, below a container filled with water, and judging that the target gas is filled in the quantitative pipe when uniform bubbling is observed.
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| CN202010182661.6A CN111122800A (en) | 2020-03-16 | 2020-03-16 | Low-concentration gas standard sample preparation device and method |
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| CN202010182661.6A CN111122800A (en) | 2020-03-16 | 2020-03-16 | Low-concentration gas standard sample preparation device and method |
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| CN111122800A true CN111122800A (en) | 2020-05-08 |
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| CN202010182661.6A Pending CN111122800A (en) | 2020-03-16 | 2020-03-16 | Low-concentration gas standard sample preparation device and method |
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