Gas analysis standard dilution device

Abstract

The invention discloses a gas analysis standard dilution device which comprises a dilution cylinder with an opening in the upper end, a piston is slidably installed in the dilution cylinder in a sealed mode and connected with a piston rod, the piston rod extends out of the opening in the upper end of the dilution cylinder, and a gas outlet pipe opening is formed in the bottom of the dilution cylinder. A first air suction pipe opening and a second air suction pipe opening are symmetrically formed in the side wall of the lower end of the dilution cylinder, the inner diameter of the first air suction pipe opening is unequal to that of the second air suction pipe opening, an observation window is formed in the dilution cylinder, and scale marks for displaying the position of the piston are arranged on the observation window. A first air suction control valve and a second air suction control valve are detachably installed on the first air suction pipe opening and the second air suction pipe opening respectively, an air outlet control valve is detachably connected to the air outlet pipe opening, and a limiting adjusting structure for adjusting the movement limit position of the piston is further arranged at the opening of the upper end of the dilution barrel. The standard dilution device can quickly and accurately dilute the sampled gas, and is simpler to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of gas analysis, and in particular to a gas analysis standard dilution device. Background Art

[0002] When conducting gas chemical analysis, two gases need to be diluted proportionally with a diluent gas. Patent application number CN210347575U discloses a simple standard gas dilution device that can be used to dilute two gases proportionally. However, this device is primarily used for configuring two gases within a laboratory and is relatively expensive, requiring storage of gas cylinders, flow meters, and flow control valves.

[0003] However, for many gas detection, the above dilution device is not applicable. The gas sampled on site is generally stored in an air bag, and then the sample gas and dilution gas in the air bag need to be diluted proportionally.

[0004] However, since the sample gas is stored in the air bag, the above-mentioned simple standard gas dilution device is obviously not applicable. This is because the gas in the above-mentioned simple standard gas dilution device is stored in the gas cylinder, and the positive pressure in the gas cylinder is used as the driving force for the gas flow, while the sampling gas exists in the air bag and cannot be diluted and configured in the above manner.

[0005] Therefore, the current specific operating method is to use a suction syringe to connect the air outlet of the air bag, then extract a certain amount of gas, and then separate it and connect the suction syringe to the air outlet of the dilution gas to extract the dilution gas. The suction amount of the sample gas and the dilution gas requires human eyes to observe the piston position of the suction syringe to judge the amount of gas inhaled, and two suctions are required during the suction. After the suction is completed, the end connector of the suction syringe is removed and connected to the air inlet of the spectrometer, and the piston of the syringe is squeezed to squeeze the gas into the spectrometer for spectral analysis.

[0006] Therefore, the current whole process is relatively cumbersome and the accuracy is not high. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a gas analysis standard dilution device, which can quickly and accurately dilute the sampled gas and is simpler to operate.

[0008] To solve the above technical problems, the technical solution of the present invention is: a gas analysis standard dilution device, comprising a dilution cylinder with an upper end opening, a piston being sealed and slidably installed in the dilution cylinder, the piston being connected to a piston rod, and the piston rod extending from the opening at the upper end of the dilution cylinder, an air outlet pipe opening being provided at the bottom of the dilution cylinder, a first intake pipe opening and a second intake pipe opening being symmetrically provided on the side wall of the lower end of the dilution cylinder, the inner diameters of the first intake pipe opening and the second intake pipe opening being unequal, an observation window being provided on the dilution cylinder, a scale mark showing the position of the piston being provided on the observation window, a first intake control valve and a second intake control valve being detachably installed on the first intake pipe opening and the second intake pipe opening, respectively, the air outlet control valve being detachably connected to the air outlet pipe opening, and a limit adjustment structure for adjusting the limit position of movement of the piston is also provided at the upper end opening of the dilution cylinder.

[0009] As a preferred solution, the limit adjustment structure includes a limit mounting plate that is detachably fixedly mounted on the upper end of the dilution cylinder, and the limit mounting plate partially covers the inner cavity of the dilution cylinder. A limit plate is provided above the piston in the dilution cylinder, and an axially extending connecting shaft is provided on the limit plate. The connecting shaft passes through the limit mounting plate and is fastened by a nut.

[0010] As a preferred solution, the first intake control valve and the second intake control valve have the same structure, the first intake control valve includes an upper valve cylinder and a lower valve cylinder that are detachably connected to each other, a valve plate is provided in the lower valve cylinder, an air flow hole is provided on the valve plate, a valve ball is axially slidably installed in the lower valve cylinder, the valve ball is sealed with the upper opening of the air flow hole, a compression spring is provided on the upper valve cylinder to force the valve ball to seal with the upper opening of the air flow hole, the upper valve cylinder is detachably connected to the first intake pipe port, and the lower end of the lower valve cylinder is provided with a pipeline connection structure that is convenient for connecting with the gas pipeline.

[0011] As a preferred solution, the pipeline connection structure is a threaded connection structure.

[0012] As a preferred solution, the valve ball is provided with an upwardly extending guide rod, the upper valve cylinder is provided with a guide bracket, the guide bracket includes an outer fixing ring, an inner guide ring and a connecting rib connecting the outer fixing ring and the inner guide ring, the guide rod passes through the inner guide ring, a locking nut is provided on the guide rod above the guide bracket, the compression spring is sleeved on the guide rod and pre-compressed between the guide bracket and the valve ball.

[0013] As a preferred solution, the upper end of the upper valve cylinder and the lower end of the lower valve cylinder are both provided with internal threads and external threads. The structure of the air outlet control valve is the same as that of the first air intake control valve, but the position is inverted. The guide rod of the air outlet control valve is set downward, and the valve ball of the air outlet control valve is sealed with the lower end of the air flow channel through a compression spring.

[0014] As a preferred solution, the air outlet pipe port, the first air intake pipe port and the second air intake pipe port are all movably sleeved with a threaded connection sleeve, and the air outlet pipe port, the first air intake pipe port and the second air intake pipe port are all provided with a flange edge for limiting the threaded connection sleeve, and the first air intake control valve, the second air intake control valve and the air outlet control valve are respectively threadedly connected to the corresponding threaded connection sleeves.

[0015] As a preferred solution, the valve plate is provided with a spherical sealing surface that cooperates with the spherical surface of the valve ball in a sealing manner.

[0016] The lip of described outer combustion gas heating unit is connected with the piston rod of described outer combustion gas heating unit, and the piston rod of described outer combustion gas heating unit is connected with the piston rod of described piston rod, and the piston rod extends from the opening of upper end of described oil pumping cylinder. The valve is connected to the outlet pipe of the dilution gas container, and the outlet control valve is connected to the spectrometer. Pull the piston rod upward to suction. During the suction process, since the inner diameters between the first suction pipe port and the second suction pipe port are not equal, the flow rates between the first suction pipe port and the second suction pipe port are different. Therefore, after selecting the appropriate inner diameter in advance, the suction amount of the sample gas and the dilution gas can be accurately controlled. During the suction process, the air pressure change ΔP in the dilution cylinder is the same for the sample gas and the dilution gas. For the gas, ignoring the friction resistance of the gas pipeline and the density difference between the dilution gas and the sample gas (the dilution gas used in actual operation is generally a gas close to the sample gas, for example, when sampling the external atmospheric environment gas, the dilution gas is generally nitrogen. The molar mass of air is 29, and the average molar mass of nitrogen is 28, and the difference is very small), considering the conversion of pressure into kinetic energy, the relationship between flow rate and pressure: According to Bernoulli's equation, flow rate Where ΔP is the pressure difference and ρ is the fluid density; and according to the flow formula, D is the inner diameter, Q1 represents the flow rate of the first suction pipe port, Q2 represents the flow rate of the second suction pipe port, D1 is the inner diameter of the first suction pipe port, D2 is the inner diameter of the second suction pipe port, and the above flow rate is substituted into the flow formula to calculate Q1 / Q2, and we can get Q1 / Q2∝D1 2 / D2 2 Therefore, the flow rate ratio between the sample gas and the dilution gas at the first suction pipe port and the second suction pipe port is equal to the ratio of the square of the corresponding inner diameter. Therefore, as long as the first suction pipe port and the second suction pipe port with appropriate corresponding inner diameters are selected in advance according to the dilution ratio, the dilution cylinder can extract and complete the mixed dilution between the sample gas and the dilution gas at one time, and the limit adjustment structure can adjust the movement limit position of the piston, so that the total gas volume extracted at one time can be controlled, and the total volume after dilution can be calculated more conveniently. When the suction and mixing are completed, the piston moves downward. At this time, the first suction control valve and the second suction control valve are closed, and the outlet control valve is opened, so that the mixed gas in the dilution cylinder can be squeezed into the spectrometer for analysis. The standard dilution device has a simple structure and is easy to operate, and can quickly meet the dilution requirements between the sample gas and the dilution gas.

[0017] Furthermore, since the limit adjustment structure includes a limit mounting plate that is detachably fixedly mounted on the upper end of the dilution cylinder, the limit mounting plate partially covers the inner cavity of the dilution cylinder, and a limit plate is provided above the piston in the dilution cylinder, an axially extending connecting shaft is provided on the limit plate, and the connecting shaft passes through the limit mounting plate and is fastened by a nut. Therefore, by loosening the nut, the position of the limit plate can be changed, thereby realizing the limit adjustment of the piston position.

[0018] Since the first suction control valve and the second suction control valve have the same structure, the first suction control valve includes an upper valve cylinder and a lower valve cylinder that are detachably connected to each other, a valve plate is provided in the lower valve cylinder, an air flow hole is provided on the valve plate, a valve ball is axially slidably installed in the lower valve cylinder, the valve ball is sealed with the upper opening of the air flow hole, a compression spring is provided on the upper valve cylinder to force the valve ball to seal with the upper opening of the air flow hole, the upper valve cylinder is detachably connected to the first suction pipe port and the second suction pipe port, and the lower end of the lower valve cylinder is provided with a A pipeline connection structure is provided, and the first suction control valve and the second suction control valve have a simple structure. When pumping air, due to the negative pressure generated in the dilution cylinder, the pressure difference between the upper and lower parts of the valve ball will force the valve ball to move upward and continue to compress the spring, thereby opening the air flow holes on the valve plates of the first suction control valve and the second suction control valve. In this way, the first suction control valve and the second suction control valve will automatically open during the suction process, and when the suction action stops, the valve ball will close the air flow holes of the valve plate under the action of the compression spring, and the whole process does not require manual operation.

[0019] Since the valve ball is provided with an upwardly extending guide rod, the upper valve cylinder is provided with a guide bracket, the guide bracket includes an outer fixing ring, an inner guide ring and a connecting rib connecting the outer fixing ring and the inner guide ring, the guide rod passes through the inner guide ring, and a locking nut is provided on the guide rod above the guide bracket. The compression spring is sleeved on the guide rod and pre-pressed between the guide bracket and the valve ball. The guide bracket can play a limiting and guiding role in the sliding of the valve ball, thereby ensuring the accurate opening and closing of the valve ball.

[0020] Since the upper end of the upper valve cylinder and the lower end of the lower valve cylinder are both provided with internal threads and external threads, the structure of the air outlet control valve is the same as the structure of the first intake control valve, and the position is inverted. The guide rod of the air outlet control valve is set downward, and the valve ball of the air outlet control valve is sealed with the lower mouth of the air flow channel through a compression spring. In this way, the overall structure of the air outlet control valve, the first intake control valve, and the second intake control valve is the same, but the connection method is different. The air outlet control valve is actually the state of the first intake control valve after inverted connection, which makes it simpler to connect, and only needs to produce control valves with the same structure to meet the requirements of air outlet and air intake at the same time. The overall production cost is also lower, and the components of each control valve can also be replaced with each other, which is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and examples.

[0022] Figure 1 is a perspective view of an embodiment of the present invention;

[0023] Figure 2 is a front view of an embodiment of the present invention;

[0024] Figure 3 yes Figure 2 Structural cross-section along AA;

[0025] Figure 4 yes Figure 3 Enlarged view of some structures;

[0026] Figure 5 is a top view of an embodiment of the present invention;

[0027] Figure 6 yes Figure 5 Partial structural cross-sectional view along BB;

[0028] In the accompanying drawings: 1. Dilution cylinder; 2. Piston; 3. Piston rod; 4. Air outlet pipe; 5. First air intake pipe; 6. Second air intake pipe; 7. Observation window; 8. First air intake control valve; 81. Upper valve cylinder; 82. Lower valve cylinder; 83. Valve plate; 84. Air flow hole; 85. Valve ball; 86. Compression spring; 87. Pipe connection structure; 88. Guide rod; 89. Outer fixing ring; 810. Inner guide ring; 811. Connecting rib; 9. Second air intake control valve; 10. Air outlet control valve; 11. Limit adjustment structure; 111. Limit mounting plate; 112. Limit plate; 113. Connecting shaft; 12. Flange; 13. Threaded connection sleeve. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below through specific examples.

[0030] like Figure 1-6 As shown, a gas analysis standard dilution device comprises a dilution cylinder 1 with an opening at the upper end, a piston 2 is sealingly and slidingly installed in the dilution cylinder 1, the piston 2 is connected to a piston rod 3, the piston rod 3 extends from the opening at the upper end of the dilution cylinder 1, an air outlet pipe port 4 is provided at the bottom of the dilution cylinder 1, a first air intake pipe port 5 and a second air intake pipe port 6 are symmetrically provided on the side wall of the lower end of the dilution cylinder 1, the inner diameters of the first air intake pipe port 5 and the second air intake pipe port 6 are not equal, an observation window 7 is provided on the dilution cylinder 1, and a scale mark showing the position of the piston 2 is provided on the observation window 7, a first air intake control valve 8 and a second air intake control valve 9 are detachably installed on the first air intake pipe port 5 and the second air intake pipe port 6, respectively, an air outlet control valve 10 is detachably connected to the air outlet pipe port 4, and a limit adjustment structure 11 for adjusting the limit position of movement of the piston 2 is also provided at the upper end opening of the dilution cylinder 1.

[0031] In this embodiment, the limit adjustment structure 11 includes a limit mounting plate 111 that is detachably fixedly mounted on the upper end of the dilution cylinder 1. The limit mounting plate 111 partially covers the inner cavity of the dilution cylinder 1. A limit plate 112 is provided above the piston 2 in the dilution cylinder 1. An axially extending connecting shaft 113 is provided on the limit plate 112. The connecting shaft 113 passes through the limit mounting plate 111 and is fastened by a nut.

[0032] The first intake control valve 8 and the second intake control valve 9 have the same structure. The first intake control valve 8 comprises an upper valve cylinder 81 and a lower valve cylinder 82 that are detachably connected to each other. In this embodiment, the upper valve cylinder 81 and the lower valve cylinder 82 are threadedly connected. Of course, other detachable connection methods can also be selected as needed. A valve plate 83 is provided in the lower valve cylinder 82, and an air flow hole 84 is provided on the valve plate 83. A valve ball 85 is axially slidably mounted in the lower valve cylinder 82, and the valve ball 85 seals with the upper end of the air flow hole 84. A compression spring 86 is provided on the upper valve cylinder 81 to force the valve ball 85 to seal with the upper end of the air flow hole 84. The upper valve cylinder 81 is detachably connected to the first intake pipe port 5. The lower end of the lower valve cylinder 82 is provided with a pipe connection structure 87 that facilitates communication with the gas pipeline. In this embodiment, the pipe connection structure 87 is a threaded connection structure.

[0033] A guide rod 88 extending upward is provided on the valve ball 85, and a guide bracket is provided on the upper valve cylinder 81. The guide bracket includes an outer fixing ring 89, an inner guide ring 810 and a connecting rib 811 connecting the outer fixing ring 89 and the inner guide ring 810. The guide rod 88 passes through the inner guide ring 810. A locking nut is provided on the guide rod 88 above the guide bracket. A compression spring 86 is sleeved on the guide rod 88 and pre-loaded between the guide bracket and the valve ball 85.

[0034] In this embodiment, the upper end of the upper valve cylinder 81 and the lower end of the lower valve cylinder 82 are both provided with internal and external threads. The structure of the outlet control valve 10 is identical to that of the first intake control valve 8, but inverted, with the guide rod 88 of the outlet control valve 10 facing downward. The valve ball 85 of the outlet control valve 10 is sealed with the lower end of the airflow channel via a compression spring 86. The outlet pipe port 4, the first intake pipe port 5, and the second intake pipe port 6 are all movably fitted with threaded connection sleeves 13. Flanges 12 are also provided on the outlet pipe port 4, the first intake pipe port 5, and the second intake pipe port 6 to restrict the threaded connection sleeves 13. The first intake control valve 8, the second intake control valve 9, and the outlet control valve 10 are respectively threadedly connected to the corresponding threaded connection sleeves 13. The valve plate 83 is provided with a spherical sealing surface that spherically seals with the valve ball 85.

[0035] First, select the appropriate inner diameter of the first intake pipe and the second intake pipe according to the requirements of the gas analysis dilution ratio. During use, one of the intake control valves is connected to the outlet pipe of the air bag containing the sample gas, and the other intake control valve is connected to the outlet pipe of the dilution gas container. The outlet control valve 10 is connected to the spectrometer, and the piston rod 3 is pulled upward for suction. During the suction process, since the inner diameters between the first intake pipe port 5 and the second intake pipe port 6 are not equal, the flow rates between the first intake pipe port 5 and the second intake pipe port 6 are different. After selecting the first intake pipe port 5 and the second intake pipe port 6 with appropriate inner diameters, the suction amount of the sample gas and the dilution gas can be accurately controlled according to the dilution ratio. The first and second suction control valves 8 and 9 have simple structures. When the piston 2 moves upward to pump air, negative pressure forms within the dilution cylinder 1. The pressure differential between the valve ball 85 and the valve plate 83 forces the valve ball 85 upward, further compressing the spring 86. This opens the air flow holes 84 on the valve plates 83 of the first and second suction control valves 8 and 9, allowing them to automatically open during the suction process. At this point, the outlet control valve 10 closes, allowing the sample gas and dilution gas to be drawn into the dilution cylinder 1 for mixing. When the piston 2 moves downward, the outlet control valve 10 opens, closing the air flow holes 84 on the valve plates 83 of the first and second suction control valves 8 and 9, allowing the mixed gas in the dilution cylinder 1 to be squeezed into the spectrometer for analysis. The limit adjustment structure 11 can adjust the limit position of the piston 2. Loosening the nut changes the position of the limit plate 112 to achieve limit adjustment of the piston 2 position, thereby controlling the total volume of gas extracted at one time.

[0036] During the suction process, the pressure change ΔP in the dilution cylinder 1 is the same for both the sample gas and the dilution gas. For the gas, ignoring the friction resistance of the gas pipeline and the density difference between the dilution gas and the sample gas (the dilution gas used in actual operation is generally a gas close to the sample gas. For example, when sampling the external atmospheric environment gas, the dilution gas is generally nitrogen. The molar mass of air is 29, and the average molar mass of nitrogen is 28, and the difference is very small), considering the conversion of pressure into kinetic energy, the relationship between flow rate and pressure is: According to the Bernoulli equation, the flow rate Where ΔP is the pressure difference and ρ is the fluid density; and according to the flow formula, Q1 represents the flow rate of the first suction pipe port 5, Q2 represents the flow rate of the second suction pipe port 6, D1 is the inner diameter of the first suction pipe port 5, and D2 is the inner diameter of the second suction pipe port 6. After substituting the above flow rate, we can get Q1 / Q2∝D1 2 / D2 2Therefore, the flow rate ratio between the sample gas and the dilution gas at the first suction pipe port 5 and the second suction pipe port 6 is equal to the ratio of the squares of the inner diameters of the corresponding first suction pipe port 5 and the second suction pipe port 6. Therefore, as long as the appropriate corresponding inner diameter is selected in advance according to the dilution ratio, the dilution cylinder 1 can extract and complete the mixing and dilution between the sample gas and the dilution gas at one time.

[0037] The air circuit system and the screw-nut mechanism mentioned in this embodiment are all current conventional technologies. The specific structure, principle and other designs of the cylinder and other transmission mechanisms are disclosed in detail in the "Mechanical Design Manual, Fifth Edition", the 28th printing of the fifth edition in Beijing in April 2008. They belong to the existing technology and their structure is clear.

[0038] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Various modifications and alterations to the technical solutions of the present invention without departing from the spirit of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A gas analysis standard dilution device, comprising a dilution cylinder with an open top, a piston slidably mounted in the cylinder, the piston being connected to a piston rod extending from the opening at the top of the cylinder, characterized in that: The bottom of the dilution cylinder is provided with an air outlet pipe port, and a first air intake pipe port and a second air intake pipe port are symmetrically provided on the side wall of the lower end of the dilution cylinder. The inner diameters of the first air intake pipe port and the second air intake pipe port are not equal. The dilution cylinder is provided with an observation window, and a scale mark showing the position of the piston is provided on the observation window. The first air intake pipe port and the second air intake pipe port are respectively detachably mounted with a first air intake control valve and a second air intake control valve, and the air outlet pipe port is detachably connected to the air outlet control valve. The upper end opening of the dilution cylinder is also provided with a limit adjustment structure for adjusting the limit position of piston movement.

2. A gas analysis standard dilution device according to claim 1, characterized in that: The limit adjustment structure includes a limit mounting plate detachably fixedly mounted on the upper end of the dilution cylinder, the limit mounting plate partially covering the inner cavity of the dilution cylinder, a limit plate is provided above the piston in the dilution cylinder, an axially extending connecting shaft is provided on the limit plate, the connecting shaft passes through the limit mounting plate and is fastened by a nut.

3. A gas analysis standard dilution device according to claim 1 or 2, characterized in that: The first suction control valve and the second suction control valve have the same structure. The first suction control valve includes an upper valve cylinder and a lower valve cylinder that are detachably connected to each other. A valve plate is provided in the lower valve cylinder, and an air flow hole is provided on the valve plate. A valve ball is axially slidably installed in the lower valve cylinder, and the valve ball is sealed with the upper opening of the air flow hole. A compression spring is provided on the upper valve cylinder to force the valve ball to seal with the upper opening of the air flow hole. The upper valve cylinder is detachably connected to the first suction pipe port, and the lower end of the lower valve cylinder is provided with a pipeline connection structure that is convenient for communication with the gas pipeline.

4. A gas analysis standard dilution device according to claim 3, characterized in that: The pipeline connection structure is a threaded connection structure.

5. A gas analysis standard dilution device as claimed in claim 3, characterized in that: The valve ball is provided with an upwardly extending guide rod, and the upper valve cylinder is provided with a guide bracket. The guide bracket includes an outer fixing ring, an inner guide ring and a connecting rib connecting the outer fixing ring and the inner guide ring. The guide rod passes through the inner guide ring. A locking nut is provided on the guide rod above the guide bracket. The compression spring is sleeved on the guide rod and pre-compressed between the guide bracket and the valve ball.

6. A gas analysis standard dilution device according to claim 3, characterized in that: The upper end of the upper valve cylinder and the lower end of the lower valve cylinder are both provided with internal threads and external threads. The structure of the air outlet control valve is the same as that of the first air intake control valve, but the position is inverted. The guide rod of the air outlet control valve is set downward, and the valve ball of the air outlet control valve is sealed with the lower mouth of the air flow hole through a compression spring.

7. A gas analysis standard dilution device according to claim 1 or 2, characterized in that: The air outlet pipe port, the first air intake pipe port and the second air intake pipe port are all movably provided with a threaded connection sleeve, and the air outlet pipe port, the first air intake pipe port and the second air intake pipe port are all provided with a flange edge that limits the threaded connection sleeve, and the first air intake control valve, the second air intake control valve and the air outlet control valve are respectively threadedly connected to the corresponding threaded connection sleeve.

8. A gas analysis standard dilution device as claimed in claim 3, characterized in that: The valve plate is provided with a spherical sealing surface which is in sealing cooperation with the spherical surface of the valve ball.

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