Gas analysis standard dilution device

Abstract

The utility model discloses a standard dilution device for gas analysis, which comprises a dilution cylinder with an opening at the upper end, a piston is slidably mounted in the dilution cylinder in a sealed manner and connected with a piston rod, the piston rod extends out of the opening at the upper end of the dilution cylinder, and a gas outlet pipe orifice is arranged at 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

A gas analysis standard dilution device Technical Field

[0001] This utility model relates to the field of gas analysis technology, and in particular to a gas analysis standard dilution device. Background Technology

[0002] In gas chemical analysis, two gases need to be diluted with a diluent gas in a specific ratio. Utility model patent CN210347575U discloses a simple standard gas dilution device that can be used to dilute two gases in a specific ratio. However, this device is mainly used for preparing two laboratory gases and is relatively expensive, requiring storage cylinders, flow meters, and flow control valves.

[0003] However, the aforementioned dilution device is not suitable for many gas detection applications. Gases sampled on-site are typically stored in gas bags, and then the sampled gas and diluent gas within the gas bag need to be diluted according to a specific ratio.

[0004] Since the sample gas is stored in a gas bag, the aforementioned simple standard gas dilution device is obviously not applicable. This is because the gas in the aforementioned simple standard gas dilution device is stored in a gas cylinder, and the positive pressure inside the gas cylinder is used as the driving force for gas flow. However, the sample gas is stored in a gas bag, so it cannot be diluted and prepared in the above manner.

[0005] Therefore, the current specific operating method is to use a suction syringe connected to the outlet of the gas bag, then extract a certain amount of gas, separate it, and then connect the suction syringe to the outlet of the dilution gas to extract the dilution gas. The amount of sample gas and dilution gas extracted needs to be determined by visually observing the position of the piston of the suction syringe. Moreover, the suction needs to be performed twice. After the suction is completed, the end connector of the suction syringe is removed and connected to the inlet of the spectrometer. Squeezing the piston of the syringe forces the gas into the spectrometer for spectral analysis.

[0006] Therefore, the current process is relatively cumbersome and not very accurate. Summary of the Invention

[0007] The technical problem to be solved by this utility model is to provide a gas analysis standard dilution device that can quickly and accurately dilute the sampled gas and is simpler to operate.

[0008] To solve the above-mentioned technical problems, the technical solution of this utility model is: a gas analysis standard dilution device, including a dilution cylinder with an open top, a piston slidably installed inside the dilution cylinder, the piston being connected to a piston rod, the piston rod extending from the opening at the top of the dilution cylinder, an outlet port being provided at the bottom of the dilution cylinder, a first intake port and a second intake port being symmetrically arranged on the lower side wall of the dilution cylinder, the inner diameters of the first intake port and the second intake port being unequal, an observation window being provided on the dilution cylinder, the observation window being provided with a scale marking indicating the piston position, a first intake control valve and a second intake control valve being detachably installed on the first intake port and the second intake port respectively, an outlet control valve being detachably connected to the outlet port, and a limit adjustment structure for adjusting the piston's movement limit position being provided at the upper opening of the dilution cylinder.

[0009] As a preferred embodiment, the limiting adjustment structure includes a limiting mounting plate that is detachably and fixedly installed on the upper end of the dilution cylinder. The limiting mounting plate partially covers the inner cavity of the dilution cylinder. A limiting plate is provided inside the dilution cylinder above the piston. An axially extending connecting shaft is provided on the limiting plate. The connecting shaft passes through the limiting mounting plate and is fastened with a nut.

[0010] As a preferred embodiment, the first and second intake control valves 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 inside the lower valve cylinder, and an air passage hole is provided on the valve plate. A valve ball is axially slidably installed inside the lower valve cylinder, and the valve ball is sealed to the upper opening of the air passage 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 passage hole. The upper valve cylinder is detachably connected to the first intake port. The lower end of the lower valve cylinder is provided with a pipe connection structure for easy connection to a gas pipeline.

[0011] As a preferred embodiment, the pipe connection structure is a threaded connection structure.

[0012] As a preferred embodiment, 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, and a compression spring is fitted on the guide rod and pre-compresses the guide bracket and the valve ball.

[0013] As a preferred embodiment, the upper end of the upper valve cylinder and the lower end of the lower valve cylinder are both provided with internal and external threads. The structure of the exhaust control valve is the same as that of the first intake control valve, but the position is reversed. The guide rod of the exhaust control valve is set downward. The valve ball of the exhaust control valve is sealed with the lower opening of the airflow channel by a compression spring.

[0014] As a preferred embodiment, threaded connecting sleeves are movably fitted on the air outlet, the first air intake, and the second air intake. Flanges that restrict the threaded connecting sleeves are provided on the air outlet, the first air intake, and the second air intake. 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 connecting sleeves.

[0015] As a preferred embodiment, the valve plate is provided with a spherical sealing surface that mates with the spherical seal of the valve ball.

[0016] After adopting the above technical solution, the effect of this utility model is as follows: A gas analysis standard dilution device includes a dilution cylinder with an open top. A piston is slidably installed inside the dilution cylinder, and the piston is connected to a piston rod. The piston rod extends from the opening at the top of the dilution cylinder. An outlet is provided at the bottom of the dilution cylinder. A first and second inlet are symmetrically arranged on the lower side wall of the dilution cylinder. The inner diameters of the first and second inlet are not equal. An observation window is provided on the dilution cylinder, and a scale marking indicating the piston position is provided on the observation window. A first and second inlet control valves are detachably installed on the first and second inlet ports, respectively. An outlet control valve is detachably connected to the outlet port. A limit adjustment structure for adjusting the piston's movement limit position is also provided at the upper opening of the dilution cylinder. Therefore, during operation, one inlet control valve is connected to the outlet pipe of the gas bag containing the sample gas, and the other inlet control valve... The control valve connects to the outlet pipe of the dilution gas container, and the outlet control valve is connected to the spectrometer. Pulling the piston rod upwards initiates suction. During suction, because the inner diameters of the first and second suction ports are unequal, the flow rates between them differ. Therefore, by pre-selecting a suitable inner diameter, the suction volume of the sample gas and dilution gas can be precisely controlled. Since the pressure change ΔP inside the dilution cylinder is the same for both the sample gas and the dilution gas during suction, and ignoring the gas pipe friction resistance and the density difference between the dilution gas and the sample gas (in practice, the dilution gas used is generally a gas similar to the sample gas; for example, when sampling ambient air, nitrogen is typically used as the dilution gas, as the molar mass of air is 29 and the average molar mass of nitrogen is 28, a very small difference), considering the conversion of pressure into kinetic energy, the relationship between flow velocity and pressure is as follows: According to Bernoulli's equation, the flow velocity... Where ΔP is the pressure difference and ρ is the fluid density; and according to the flow rate formula... D is the inner diameter, Q1 represents the flow rate at the first intake port, Q2 represents the flow rate at the second intake port, D1 is the inner diameter of the first intake port, and D2 is the inner diameter of the second intake port. Substituting the above flow velocities into the flow rate formula, we can calculate Q1 / Q2, thus obtaining Q1 / Q2 ∝ D1. 2 / D2 2 Therefore, the flow rate ratio between the sample gas and the diluent gas at the first and second intake ports is equal to the ratio of the squares of their corresponding inner diameters. Thus, by selecting the appropriate first and second intake ports with corresponding inner diameters according to the dilution ratio in advance, the dilution cylinder can extract and complete the mixing and dilution of the sample gas and the diluent gas in one go. The limit adjustment structure can adjust the piston's movement limit position, thereby controlling the total gas volume extracted in one go and making it easier to calculate the total volume after dilution. After the extraction and mixing are completed, the piston moves downward. At this time, the first and second intake control valves are closed, and the outlet control valve is opened, allowing the mixed gas in the dilution cylinder to be squeezed into the spectrometer for analysis. This standard dilution device has a simple structure, is easy to operate, and can quickly meet the dilution requirements between the sample gas and the diluent gas.

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

[0018] Since the first and second intake control valves 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 inside the lower valve cylinder, and an air passage is provided on the valve plate. A valve ball is axially slidably installed inside the lower valve cylinder, and the valve ball is sealed to the upper opening of the air passage. A compression spring is provided on the upper valve cylinder to force the valve ball to seal with the upper opening of the air passage. The upper valve cylinder is detachably connected to the first intake port and the second intake port. The lower end of the lower valve cylinder is provided with… Equipped with a pipe connection structure, the first and second suction control valves have a simple structure. When air is pumped out, a negative pressure is formed inside the dilution cylinder. The pressure difference between the upper and lower parts of the valve ball forces the valve ball to move upward and continue to compress the spring. This opens the air passage holes on the valve plates of the first and second suction control valves. Thus, the first and second suction control valves automatically open during the suction process. When the suction stops, the valve ball closes the air passage holes on the valve plate under the action of the compressed spring. The entire process requires no manual operation.

[0019] Furthermore, since 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, and a locking nut is provided on the guide rod above the guide bracket. The compression spring is fitted on the guide rod and pre-pressed between the guide bracket and the valve ball. The guide bracket can limit and guide the sliding of the valve ball, ensuring the accurate opening and closing of the valve ball.

[0020] Furthermore, since the upper end of the upper valve cylinder and the lower end of the lower valve cylinder are both provided with internal and external threads, the structure of the exhaust control valve is the same as that of the first intake control valve, but inverted. The guide rod of the exhaust control valve is set downwards, and the valve ball of the exhaust control valve is sealed to the lower opening of the airflow channel through a compression spring. In this way, the exhaust control valve, the first intake control valve, and the second intake control valve have the same overall structure, only the connection method is different. The exhaust control valve is actually the inverted connection of the first intake control valve. This makes the connection simpler, and only control valves with the same structure need to be produced to simultaneously meet the requirements of exhaust and intake. The overall production cost is also lower, and the components of each control valve can be interchanged and used interchangeably, making it highly practical. Attached Figure Description

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

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

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

[0024] Figure 3 is a cross-sectional view of the structure along AA in Figure 2;

[0025] Figure 4 is an enlarged view of part of the structure in Figure 3;

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

[0027] Figure 6 is a partial structural cross-sectional view along BB in Figure 5;

[0028] In the attached diagram: 1. Dilution cylinder; 2. Piston; 3. Piston rod; 4. Outlet port; 5. First intake port; 6. Second intake port; 7. Observation window; 8. First intake control valve; 81. Upper valve cylinder; 82. Lower valve cylinder; 83. Valve plate; 84. Air passage; 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 intake control valve; 10. Outlet control valve; 11. Limit adjustment structure; 111. Limit mounting plate; 112. Limit plate; 113. Connecting shaft; 12. Flange edge; 13. Threaded connection sleeve. Detailed Implementation

[0029] The present invention will be further described in detail below through specific embodiments.

[0030] As shown in Figures 1-6, a gas analysis standard dilution device includes a dilution cylinder 1 with an open top. A piston 2 is slidably installed inside the dilution cylinder 1. The piston 2 is connected to a piston rod 3, which extends from the opening at the top of the dilution cylinder 1. An outlet port 4 is provided at the bottom of the dilution cylinder 1. A first intake port 5 and a second intake port 6 are symmetrically arranged on the lower side wall of the dilution cylinder 1. The inner diameters of the first intake port 5 and the second intake port 6 are not equal. An observation window 7 is provided on the dilution cylinder 1. The observation window 7 is provided with a scale marking indicating the position of the piston 2. A first intake control valve 8 and a second intake control valve 9 are detachably installed on the first intake port 5 and the second intake port 6, respectively. An outlet control valve 10 is detachably connected to the outlet port 4. A limit adjustment structure 11 for adjusting the extreme position of the piston 2 is also provided at the upper opening of the dilution cylinder 1.

[0031] In this embodiment, the limiting adjustment structure 11 includes a limiting mounting plate 111 that is detachably and fixedly installed on the upper end of the dilution cylinder 1. The limiting mounting plate 111 partially covers the inner cavity of the dilution cylinder 1. A limiting plate 112 is provided inside the dilution cylinder 1 above the piston 2. An axially extending connecting shaft 113 is provided on the limiting plate 112. The connecting shaft 113 passes through the limiting 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 includes 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 be selected as needed. A valve plate 83 is provided inside the lower valve cylinder 82, and an air passage hole 84 is provided on the valve plate 83. A valve ball 85 is axially slidably installed inside the lower valve cylinder 82. The valve ball 85 is sealed to the upper opening of the air passage 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 opening of the air passage hole 84. The upper valve cylinder 81 is detachably connected to the first intake port 5. The lower end of the lower valve cylinder 82 is provided with a pipe connection structure 87 for convenient communication with a 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 fitted on the guide rod 88 and pre-compresses 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 exhaust control valve 10 is the same as that of the first intake control valve 8, but the position is reversed. The guide rod 88 of the exhaust control valve 10 is set downwards, and the valve ball 85 of the exhaust control valve 10 is sealed to the lower opening of the airflow channel by a compression spring 86. Threaded connecting sleeves 13 are movably fitted on the exhaust port 4, the first intake port 5, and the second intake port 6. Flange edges 12 that restrict the threaded connecting sleeves 13 are provided on the exhaust port 4, the first intake port 5, and the second intake port 6. The first intake control valve 8, the second intake control valve 9, and the exhaust control valve 10 are threadedly connected to the corresponding threaded connecting sleeves 13. The valve plate 83 is provided with a spherical sealing surface that seals with the spherical surface of the valve ball 85.

[0035] First, select the appropriate inner diameter of the first and second suction tubes according to the dilution ratio requirements of the gas analysis. During use, one suction control valve is connected to the outlet pipe of the sample gas bag, and the other suction control valve is connected to the outlet pipe of the dilution gas container. The outlet control valve 10 is connected to the spectrometer. Pull the piston rod 3 upward to perform suction. During the suction process, since the inner diameters of the first suction tube port 5 and the second suction tube port 6 are not equal, the flow rates of the first suction tube port 5 and the second suction tube port 6 are different. After selecting the appropriate inner diameters of the first suction tube port 5 and the second suction tube port 6, the suction volume of the sample gas and the dilution gas can be precisely controlled according to the dilution ratio. The first and second intake control valves 8 and 9 have simple structures. When the piston 2 moves upward to draw air, a negative pressure is formed inside the dilution cylinder 1. The pressure difference between the upper and lower parts of the valve ball 85 forces the valve ball 85 to move upward and continue to compress the spring 86. This opens the air passage holes 84 on the valve plates 83 of the first and second intake control valves 8 and 9, so the first and second intake control valves 8 and 9 automatically open during the suction process. At this time, the outlet control valve 10 is closed, and the sample gas and diluent gas are drawn into the dilution cylinder 1 for mixing. When the piston 2 moves downward, the outlet control valve 10 opens, and the air passage holes 84 on the valve plates 83 of the first and second intake control valves 8 and 9 close. The mixed gas in the dilution cylinder 1 is forced into the spectrometer for analysis. The limit adjustment structure 11 can adjust the movement limit position of the piston 2. Loosening the nut changes the position of the limit plate 112, thereby limiting the position of the piston 2 and controlling the total volume of gas drawn in one operation.

[0036] During the suction process, the pressure change ΔP inside dilution cylinder 1 is the same for both the sample gas and the dilution gas. For the gas, neglecting the frictional resistance of the gas pipeline and the density difference between the dilution gas and the sample gas (in actual operation, the dilution gas used is generally a gas close to the sample gas; for example, when sampling ambient air, nitrogen is generally used as the dilution gas, as the molar mass of air is 29 and the average molar mass of nitrogen is 28, the difference is very small), considering the conversion of pressure into kinetic energy, the relationship between flow velocity and pressure is as follows: According to Bernoulli's equation, the flow velocity... Where ΔP is the pressure difference and ρ is the fluid density; and according to the flow rate formula... Q1 represents the flow rate at the first intake port 5, Q2 represents the flow rate at the second intake port 6, D1 is the inner diameter of the first intake port 5, and D2 is the inner diameter of the second intake port 6. Substituting the flow rates into the above values, we can obtain Q1 / Q2 ∝ D1. 2 / D2 2Therefore, the flow rate ratio between the sample gas and the diluent gas at the first intake port 5 and the second intake port 6 is equal to the ratio of the squares of the inner diameters of the corresponding first intake port 5 and the second intake port 6. Thus, as long as a suitable 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 diluent gas in one go.

[0037] The pneumatic system and lead screw and nut mechanism mentioned in this embodiment are conventional technologies. The specific structure, principle and other design of cylinders and other transmission mechanisms are disclosed in detail in the 28th printing of the fifth edition of "Mechanical Design Handbook" in Beijing in April 2008. They belong to the prior art and their structure is clear and easy to understand.

[0038] The above-described embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Any modifications and alterations to the technical solution of the present utility model without departing from its design spirit shall fall within the protection scope defined by the claims of the present utility model.

Claims

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

2. The gas analysis standard dilution device as described in claim 1, characterized in that: The limiting adjustment structure includes a limiting mounting plate that is detachably and fixedly installed on the upper end of the dilution cylinder. The limiting mounting plate partially covers the inner cavity of the dilution cylinder. A limiting plate is provided inside the dilution cylinder above the piston. An axially extending connecting shaft is provided on the limiting plate. The connecting shaft passes through the limiting mounting plate and is fastened with a nut.

3. A gas analysis standard dilution apparatus as described in claim 1 or 2, characterized in that: The first and second intake control valves 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 inside the lower valve cylinder, and an air passage hole is provided on the valve plate. A valve ball is axially slidably installed inside the lower valve cylinder. The valve ball is sealed to the upper opening of the air passage 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 passage hole. The upper valve cylinder is detachably connected to the first intake port. The lower end of the lower valve cylinder is provided with a pipe connection structure for easy connection to a gas pipeline.

4. The gas analysis standard dilution device as described in claim 3, characterized in that: The pipe connection structure is a threaded connection structure.

5. The gas analysis standard dilution device as described 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, and a locking nut is provided on the guide rod above the guide bracket. The compression spring is fitted on the guide rod and pre-compresses the guide bracket and the valve ball.

6. The gas analysis standard dilution device as described in 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 and external threads. The structure of the exhaust control valve is the same as that of the first intake control valve, but the position is reversed. The guide rod of the exhaust control valve is set downward. The valve ball of the exhaust control valve is sealed with the lower opening of the air passage through a compression spring.

7. A gas analysis standard dilution apparatus as described in claim 1 or 2, characterized in that: The outlet, the first intake, and the second intake are all fitted with threaded connecting sleeves. The outlet, the first intake, and the second intake are all provided with flanges that restrict the threaded connecting sleeves. The first intake control valve, the second intake control valve, and the outlet control valve are threadedly connected to their respective threaded connecting sleeves.

8. The gas analysis standard dilution apparatus as described in claim 3, characterized in that: The valve plate is provided with a spherical sealing surface that seals with the spherical surface of the valve ball.

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