Gas mixing sampling tube
By employing cross-arranged spiral blades and a segmented variable spiral angle mixing core in the gas mixing sampling tube, the problem of insufficient mixing under different flow rates in traditional sampling tubes is solved, achieving efficient and uniform gas mixing under all operating conditions and improving detection accuracy.
Patent Information
- Application Number
- CN202610064700.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-19
- Publication Date
- 2026-03-06
AI Technical Summary
In portable gas leak detectors, traditional sampling tubes do not mix well at high and low flow rates, resulting in large errors in concentration detection results and affecting the reliability of monitoring data.
A gas mixing sampling tube is designed, which adopts a cross-arranged spiral blade structure and a segmented mixing core with variable spiral angle, combined with flow channel geometry optimization, to achieve adaptive gas mixing.
It can achieve efficient and uniform gas mixing at different flow rates, improving the accuracy of concentration detection and the adaptability of the sampling tube to all operating conditions.
Smart Images
Figure CN121612658A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas mixing technology, and more specifically to a gas mixing sampling tube. Background Technology
[0002] Portable leak detectors are widely used in current industrial gas leak detection, especially for monitoring greenhouse gas emissions such as methane. Their working principle involves placing a sampling probe (the end of the sampling tube) near the suspected leak point. The instrument's built-in pump draws in the leaking gas along with a large amount of background air. The instrument then extracts a small sample from this mixed gas flow for analysis. By measuring the concentration of the target gas in this sample and combining it with the known total sampling flow rate, the leak amount is calculated. However, the accuracy of this process heavily relies on one premise: the trace sample gas extracted for analysis must be able to fully represent the average concentration of the target gas in the entire intake gas flow. This requires that the leaking gas and background air be thoroughly homogenized and mixed before reaching the sampling point. However, in practical applications, due to the irregular shape of the leak point, the variable gas jet pattern, and the high sampling flow rate (often hundreds of liters per minute) resulting in high airflow velocity and extremely short residence time, the mixing effect inside traditional straight tube or simple cavity sampling tubes is very poor, often resulting in concentration stratification or uneven distribution. This directly leads to a deviation between the sample concentration extracted by the instrument and the true average concentration, resulting in a significant error in the final leakage calculation, which seriously affects the reliability of monitoring data and the effectiveness of control measures.
[0003] Currently, some improvement schemes attempt to add static mixers or stirring devices inside the sampling tube. However, fixed mixing elements are difficult to adapt to a wide range of flow rate changes, from minute leaks to jet leaks. At low flow rates, the mixing is insufficient, and at high flow rates, the mixing time is too short, resulting in poor performance. On the other hand, adding active mixing devices such as electric stirrers increases the complexity of the structure, power consumption, and failure rate, making them unsuitable for testing equipment that requires portability, reliability, and often needs to operate in harsh industrial environments.
[0004] Therefore, how to design a device with a simple and reliable structure that can automatically adapt to different flow rate conditions and achieve efficient and uniform gas mixing within the extremely limited space of the sampling tube has become a key technical challenge to improve the accuracy and practicality of portable gas leak detectors. Therefore, since it does not meet the existing requirements, we propose a gas mixing sampling tube. Summary of the Invention
[0005] Therefore, the present invention provides a gas mixing sampling tube to solve the above-mentioned problems in the prior art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a gas mixing sampling tube includes a first end, a second end, and a transmission hose connected between the two; both the first end and the second end have a transmission cavity and a transmission channel communicating therewith, and the side wall of the transmission channel of the second end is provided with a collection tube for extracting sample gas; a mixing core is fixedly disposed in the transmission channel of the first end. The mixing core includes a coaxially arranged cylindrical core and guide cones located at its top and bottom, respectively. An annular mixing cavity is formed between the outer wall of the cylindrical core and the inner wall of the transmission channel. At least two sets of cross-arranged spiral blades are provided on the outer wall of the cylindrical core. The spiral blades divide the annular mixing cavity into multiple interconnected spiral channels. Each spiral blade is provided with a vent hole.
[0007] Furthermore, the cross-arranged spiral plates include a first spiral plate and a second spiral plate arranged in a mirror image symmetrical to the first spiral plate. Both the first and second spiral plates are composed of multiple spiral vertical plates distributed in a ring array.
[0008] Furthermore, the first and second spiral plates intersect to form multiple continuous flow channel units with V-shaped openings at the top and bottom and a diamond-shaped space in the middle.
[0009] Furthermore, a rotating shaft is provided at the top of the guide cone above the cylindrical core, and a mixing fan is rotatably connected to the rotating shaft.
[0010] Furthermore, a blocking block is also installed below the transmission channel of the first end, downstream of the hybrid core.
[0011] Furthermore, the sealing block is provided with a gas gathering groove, a flow stabilizing groove and a gas dispersing groove connected in sequence, wherein the cross-section of the gas gathering groove gradually decreases along the airflow direction, the cross-section of the flow stabilizing groove is constant, and the cross-section of the gas dispersing groove gradually expands along the airflow direction.
[0012] Furthermore, the cylindrical core is fixed to the inner wall of the transmission channel by a crossbar.
[0013] Furthermore, both end one and end two include an annular plate and a connecting post, the transmission cavity is formed inside the annular plate, and the transmission channel is formed inside the connecting post.
[0014] Furthermore, the spiral blade is divided into at least two segments along its axial direction, and at least two of the segments have different helix angles.
[0015] Furthermore, the spiral blade is divided into an upper section, a middle section, and a lower section from top to bottom, with the axial length of each section increasing sequentially. The spiral twist angle achieved by each section is equal, thereby making the spiral angle of the upper section greater than that of the middle and lower sections.
[0016] Furthermore, the upper section with a larger helix angle is mainly used to quickly generate turbulence to initiate mixing under high flow rate conditions, while the middle and lower sections with smaller helix angles are used to provide a longer mixing path to ensure sufficient mixing under low flow rate conditions.
[0017] Furthermore, both ends of the transmission hose are respectively sealed and connected to the connecting posts of end one and end two.
[0018] The present invention has the following advantages: 1. This gas mixing sampling tube integrates a uniquely designed mixing core at its end. This mixing core combines a cross-spiral blade structure with optimized flow channel geometry, achieving a dynamic and adaptive mixing process within a fixed physical space. Specifically, multiple sets of mirror-arranged cross-spiral blades precisely divide the main airflow into several independent airflows, and repeated lateral crossing and permeation between the airflows are achieved through vents on the blades. This "segmentation-crossing-re-segmentation" mechanism creates dense velocity shear surfaces and intersection points in the flow field, greatly promoting turbulent diffusion. Thus, deep micro-mixing of leaked gas and background air is achieved within a very short flow distance, effectively solving the core defect of insufficient mixing in traditional sampling tubes. 2. This gas mixing sampling tube features a segmented, variable helix angle design for the spiral vanes. The upstream spiral segment employs a larger helix angle, rapidly inducing strong rotational shear when high flow rates arrive, injecting high mixing energy in a very short time to compensate for time. Conversely, the downstream spiral segment uses a smaller helix angle, extending the airflow path and providing ample assurance for molecular diffusion and final homogenization at low flow rates. This synergistic design of "strong shear at the front and gentle mixing at the back" allows a single fixed structure to automatically optimize its mixing at different flow rates without any adjustment components or external control, ensuring high uniformity and stability of the outlet gas across the entire operating range, from extremely low to extremely high flow rates. Attached Figure Description
[0019] Figure 1 This is a front view of a gas mixing sampling tube proposed in this invention; Figure 2 Front view of the intake and exhaust pipes; Figure 3 for Figure 2 A sectional view; Figure 4 This is a sectional view of the end. Figure 5 for Figure 4 A schematic diagram of the decomposition process; Figure 6 Front view of the cylindrical core; Figure 7This is a schematic diagram of the intersecting spiral plates; Figure 8 for Figure 7 A simplified diagram.
[0020] In the diagram: 1. End 1; 2. End 2; 301. Annular plate; 3011. Transmission cavity; 302. Connecting post; 3021. Transmission channel; 3022. Collection tube; 4. Transmission hose; 5. Mixing core; 51. Cylindrical core; 52. Guide cone; 53. Annular mixing cavity; 54. First spiral blade; 55. Second spiral blade; 56. Venturi vent; 57. Mixing fan; 58. Rotating shaft; 6. Rhomboid space; 71. Inlet pipe; 72. Exhaust pipe; 8. Sealing block; Detailed Implementation
[0021] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Example 1; Reference Figure 1 - Figure 8 A gas mixing sampling tube includes a first end 1, a second end 2, and a transmission hose 4 installed between them. Both the first end 1 and the second end 2 include an annular plate 301, with a connecting post 302 fixedly connected to one end of the annular plate 301. A transmission cavity 3011 is formed on the annular plate 301, with an open structure at the end of the transmission cavity 3011 away from the connecting post 302. A through transmission channel 3021 is formed on the inner wall of the connecting post 302, with one end of the transmission channel 3021 communicating with the inner wall of the transmission cavity 3011. The connecting post 302 of the first end 1 and the connecting post 302 of the second end 2 are connected by the transmission hose 4. A collection tube 3022 is installed on the side wall of the connecting post 302 of the second end 2, and the end of the collection tube 3022 is connected to the transmission channel 3021 opened in the inner wall of the connecting post 302. The transmission channel 3021 of the end-1 is provided with a mixing core 5, which includes a cylindrical core 51. A crossbar (not shown in the figure) runs through the middle of the cylindrical core 51. The two ends of the crossbar are fixedly connected to the inner wall of the transmission channel 3021. A guide cone 52 is fixedly installed at the top and bottom of the cylindrical core 51. Thus, an annular mixing cavity 53 is formed between the outer wall of the cylindrical core 51 and the inner wall of the transmission channel 3021. A rotating shaft 58 is fixedly installed at the top of the guide cone 52 above the cylindrical core 51. A mixing fan 57 is rotatably connected to the top outer wall of the rotating shaft 58. The usage method and working principle are as follows: Fix both ends of the transmission hose 4 to the outer wall of the connecting post 302 of one of the end caps 1 and 2 respectively, and assemble them into a complete sampling pipeline; when in use, connect end cap 1 to the output end of the air inlet pipe 71 of the equipment, connect end cap 2 to the exhaust pipe 72, connect the output end of the exhaust pipe 72 to the input end of the exhaust pump; connect the output end of the sampling tube 3022 to the gas analysis equipment (such as a concentration sensor); During operation: Start the exhaust pump to generate negative pressure at its input end; under the drive of this negative pressure, the mixture of the leaked gas to be tested and the background air is drawn in from the intake pipe 71 connected to end-1 and first enters the transmission cavity 3011 of end-1. When the gas flows through the mixing fan 57, the airflow drives its rotation, which initially stirs and disturbs the gas, achieving initial forced mixing. The initially mixed gas is smoothly guided and accelerated to the annular mixing chamber 53, which is formed by the outer wall of the upper guide cone 52 and the inner wall of the air inlet pipe 71 inserted into the transmission cavity 3011, along the downwardly narrowing guide space. The gas is then transported to the annular mixing chamber 53, which is surrounded by the outer wall of the cylindrical core 51 and the inner wall of the transmission channel 3021. After being buffered and homogenized in the annular mixing chamber 53, the gas flows through the transmission hose 4 and the second end 2 in sequence, and is finally discharged through the exhaust pipe 72. The sampling tube 3022 located on the second end 2 continuously extracts a small portion of the mixed gas sample from the transmission channel 3021 of its connecting column 302 and transports it to the subsequent analysis equipment for concentration detection, thereby calculating the leakage amount. Example 2: Similar to Embodiment 1, the technical problem with the above solution is that, although Embodiment 1 relies solely on the mixing fan 57 for initial stirring, the mixing effect may not be sufficient, especially at low airflow speeds where the fan speed is slow and the mixing intensity is insufficient; while at high speeds, the gas residence time is short, and simple stirring may not achieve completely uniform mixing. To solve this problem, a further step is to refer to... Figure 1 - Figure 8A gas mixing sampling tube, wherein two sets of spiral blades are mounted on the outer wall of the cylindrical core 51. The spiral blades can be considered as flat plates vertically mounted on the outer wall of the cylindrical core 51, and then spirally twisted around the central axis of the cylindrical core 51. The two sets of spiral blades are a first spiral blade 54 and a second spiral blade 55 arranged symmetrically to the first spiral blade 54. Multiple first spiral blades 54 and second spiral blades 55 are provided, arranged in a ring array and fixed to the outer wall of the cylindrical core 51. See [specific reference] for details. Figure 4 - Figure 6 Multiple first spiral blades 54 and second spiral blades 55 are arranged in a cross pattern to form a complex flow channel network in the annular mixing cavity 53, with V-shaped openings at the top and bottom and a series of continuous rhomboid spaces 6 in the middle; wherein, the V-shaped opening at the top faces the gas flow direction (upward), and the V-shaped opening at the bottom faces the gas flow direction (downward); a number of vent holes 56 are arrayed on the first spiral blades 54 and the second spiral blades 55 along their extension direction. In use: When the gas enters the annular mixing chamber 53, it is immediately divided into multiple independent airflows by the mirror-shaped, intersecting first spiral blade 54 and second spiral blade 55. These airflows are confined within the flow channels of the rhomboid spaces 6 formed by the intersecting spiral blades, with opposite rotation directions. During the flow, the gas passes through the vents 56 on the spiral blades, traversing laterally from one rhomboid space 6 to another adjacent rhomboid space 6 with potentially opposite airflow rotation directions. This process achieves multiple "splitting-cross-penetration-re-splitting" of the gas. Specifically, the gas enters through a V-shaped opening at the top of a rhomboid space 6, and some of the gas passes through this opening. The vents 56 on the two sides of the upper part (i.e., the two spiral segments that form the V-shaped opening) divert the gas into the two adjacent rhomboid spaces above. Inside the rhomboid space 6, the gas flows along the spiral path and exchanges gas with the adjacent space through the side vents. Finally, the gas flows out from the V-shaped opening at the bottom of the space, or enters the downstream rhomboid space again through the lower vents. This structure creates multiple shear surfaces and gas junctions, which greatly enhances the efficiency of turbulent diffusion and micro-mixing, ensuring that the leaked gas and the background air reach a highly uniform mixing state in a limited space and time, and significantly improving the accuracy of subsequent concentration detection. Furthermore, to optimize the transition of airflow from the mixing area into the transmission hose 4 and reduce eddies and pressure fluctuations, a blocking block 8 can be installed below the transmission channel 3021 of the end-1 (i.e., at the outlet of the annular mixing chamber 53). The blocking block 8 has a gradually narrowing gas-gathering groove, a constant-section flow-stabilizing groove, and a gradually expanding gas-diffusing groove from top to bottom. After being fully divided and mixed by the mixing core 5 composed of a cylindrical core 51, a guide cone 52, a first spiral blade 54, and a second spiral blade 55, the airflow first enters the gas-gathering groove to converge and then flows smoothly through the flow-stabilizing groove. Finally, it diffuses smoothly into the transmission hose 4 through the gas-diffusing groove, thereby achieving a smooth transition and delivery of the airflow, which is beneficial to maintaining the stability of the gas concentration after mixing. Example 3: Based on Example 2, in order to further optimize the mixing effect and endow it with certain adaptive characteristics to cope with a wider range of airflow velocity changes, this example refines the geometric parameters of the spiral blades; specifically as follows: Refer to Figure 7 - Figure 8 A gas mixing sampling tube divides a spiral blade (including a first spiral blade 54 and a second spiral blade 55) into three sections along its axial direction (airflow direction): upper, middle, and lower. The total theoretical twist angle of the entire spiral blade is A (e.g., 180°), and the total axial height (the length of the mixing section covering the cylindrical core 51) is B. From top to bottom, the axial height (segment length) of each of the three spiral blade sections increases sequentially, while the spiral twist angle achieved by each section is evenly distributed (i.e., the twist angle of each section is A / 3). This means that the upper spiral blade completes a twist of A / 3 within a shorter height, resulting in a larger spiral angle (helix angle), more vigorous flow channel rotation, and a shorter path. The middle and lower sections complete the same twist angle within gradually increasing heights, thus the spiral angle decreases segment by segment, the flow channel rotation becomes smoother, and the path lengthens. Working Principle: This segmented variable helix angle design essentially constructs a "rapid-to-slow" mixing channel. When gas enters the upper part of the mixing core, the larger helix angle causes the gas to rapidly generate strong rotational motion, forming initial strong shear and turbulence. This is crucial for quickly breaking the initial uneven distribution of the gas and initiating the mixing process, especially beneficial for injecting high mixing energy in a short time at high flow rates. Subsequently, as the gas enters the middle and lower sections, the helix angle decreases, the airflow rotation speed slows down, but the flow path is relatively extended. This provides gas molecules with more sufficient diffusion and time to achieve microscale homogenization, while also helping to stabilize the flow field and reduce unnecessary energy loss. This is highly beneficial for ensuring the final mixing completion at low flow rates. Therefore, this design cleverly coordinates the two factors of mixing intensity and mixing time, enabling the mixing core 5 to adapt to a wide range of flow rate conditions: at high speeds, the strong shear in the front section quickly initiates efficient mixing, while at low speeds, the extended path in the rear section ensures thorough mixing. This results in stable and excellent mixing performance under all operating conditions, improving the overall reliability and accuracy of the sampling and detection system.
Claims
1. A gas mixing sampling tube, characterized by, The device comprises a first end head (1), a second end head (2) and a transmission hose (4) connected between the two; the first end head (1) and the second end head (2) each have a transmission cavity (3011) and a transmission channel (3021) in communication with the transmission cavity (3011), and the transmission channel (3021) of the second end head (2) is provided with a collection pipe (3022) on the side wall thereof for extracting sample gas; a mixing core (5) is fixedly arranged in the transmission channel (3021) of the first end head (1); The mixing core (5) comprises a cylindrical core (51) and flow guide cones (52) arranged at the top and bottom of the cylindrical core (51) respectively, and an annular mixing cavity (53) is formed between the outer wall of the cylindrical core (51) and the inner wall of the transmission channel (3021); at least two groups of helical fins are arranged on the outer wall of the cylindrical core (51) in a cross manner, and the helical fins divide the annular mixing cavity (53) into a plurality of helical flow channels in communication with each other, and a vent hole is formed in each helical fin.
2. The gas mixing sampling tube according to claim 1, wherein The helical fins arranged in a cross manner comprise a first helical fin (54) and a second helical fin (55) arranged in a mirror-symmetrical manner with the first helical fin (54), and the first helical fin (54) and the second helical fin (55) are each composed of a plurality of helical vertical plates arranged in an annular array.
3. A gas mixing sampling tube according to claim 2, wherein The first helical fin (54) and the second helical fin (55) cross to form a plurality of continuous flow channel units with V-shaped openings at the top and bottom and rhombic spaces (6) in the middle.
4. A gas mixing sampling tube according to claim 3, wherein The flow guide cone (52) above the cylindrical core (51) is provided with a rotating shaft (58) at the top thereof, and a mixing fan (57) is rotatably connected to the rotating shaft (58).
5. A gas mixing sampling tube according to claim 4, wherein A blocking block (8) is further installed downstream of the mixing core (5) below the transmission channel (3021) of the first end head (1).
6. A gas mixing sampling tube according to claim 5, wherein A gas collecting groove, a flow stabilizing groove and a gas diffusing groove are sequentially formed in the blocking block (8) and are in communication with each other, wherein the cross section of the gas collecting groove is tapered along the direction of the gas flow, the cross section of the flow stabilizing groove is constant, and the cross section of the gas diffusing groove is expanded along the direction of the gas flow.
7. A gas mixing sampling tube according to claim 6, wherein The cylindrical core (51) is fixed to the inner wall of the transmission channel (3021) through a cross bar.
8. A gas mixing sampling tube according to claim 7, wherein The first end head (1) and the second end head (2) each comprise an annular plate (301) and a connecting column (302), the transmission cavity (3011) is formed in the annular plate (301), and the transmission channel (3021) is formed in the connecting column (302).
9. A gas mixing sampling tube according to claim 8, wherein The helical fin is divided into at least two segments along the axial direction thereof, and the helical angles of at least two of the segments are different.
10. A gas mixing sampling tube according to claim 9, wherein The helical fin is divided into an upper segment, a middle segment and a lower segment from top to bottom, the axial lengths of the segments are sequentially increased, and the helical twist angles realized by the segments are equal, so that the helical angle of the upper segment is greater than the helical angles of the middle segment and the lower segment.
11. A gas mixing sampling tube according to claim 10, wherein The upper segment with a larger helical angle is mainly used for quickly generating turbulent flow to start mixing under high flow rate conditions, and the middle segment and the lower segment with smaller helical angles are used for providing longer mixing paths to ensure sufficient mixing under low flow rate conditions.
12. A gas mixing sampling tube according to claim 11, wherein The two ends of the transmission hose (4) are sealingly connected with the connecting columns (302) of the first end head (1) and the second end head (2) respectively.