Multifunctional adjustable coal field underground gas sampling device

Abstract

The invention relates to the technical field of gas phase medium collection, in particular to a multifunctional adjustable coal field underground gas sampling device which comprises a drilling machine and a sampling barrel, the drilling machine is detachably connected with the sampling barrel, and the drilling machine is used for drilling a hole in the ground of a target layer and downwards conveying the sampling barrel to the target layer after drilling is finished; a sampling channel is formed in the sampling barrel, the bottom of the sampling channel is communicated with a sampling cabin, packers are symmetrically arranged at the top and the bottom of the sampling cabin, and the packers are used for forming a sealing ring between the sampling barrel and a hole wall after the sampling cabin reaches a target layer; one end, far away from the sampling cabin, of the sampling channel is also communicated with a negative pressure collecting mechanism; the negative pressure collecting mechanism is used for generating negative pressure in the sampling channel and storing the collected gas. The accuracy of the collected gas sample can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas phase medium collection, and particularly relates to a multifunctional adjustable coalfield underground gas sampling device. BACKGROUND

[0002] The coalfield fire area is a disastrous geological and environmental disaster in the coal mine area, and the combustion not only loses valuable coal resources, but also continuously releases a large amount of toxic and harmful gases (such as CO and SO2) and greenhouse gases (CO2), causing serious air pollution, ecological damage, and directly threatening mine production and personnel safety. Accurate detection of the coalfield fire area, identification of the fire source position, assessment of the combustion state, and monitoring of the treatment effect are extremely dependent on in-situ, horizon-specific, high-fidelity sampling and analysis of the gases in the fire area and the surrounding fracture zone and coal rock layer. The composition, concentration and isotope characteristics of the fire area marker gases (such as CO, olefins and alkane chain ratios) are the only direct evidence for inverting the fire source temperature, judging the combustion stage and identifying the gas guide channel.

[0003] At present, the acquisition of fire area gas information mainly relies on two types of technologies:

[0004] Surface or shallow borehole mixed gas sampling: directly collecting the escaped gas in the surface fracture or shallow hole of the fire area. This method can only obtain the end gas after long-distance migration and full mixing, completely losing the spatial and horizon information, and cannot trace the fire source. It is extremely easy to cause distortion of key indicators due to gas diffusion, adsorption and reaction, especially cannot distinguish between deep open fire combustion, shallow smoldering or other geological origin gases.

[0005] Simple pumping in exploration / monitoring boreholes: simple pipeline is lowered into the suspected fire area or fire extinguishing engineering borehole for gas pumping sampling, which is the relatively mainstream method at present. However, the technical principle has defects:

[0006] The coalfield fire area is a high-temperature thermal dynamic field, and when the borehole passes through different temperature combustion zones, thermal anomaly zones and unaffected coal seams, an artificial chimney effect is formed. Thermal expansion drives high-temperature gas to migrate upward, and cold air may compensate downward, thereby causing a violent forced convection cycle in the wellbore. This causes the gas at different depths in the borehole to be rapidly and thoroughly mixed, so that the finally extracted gas is actually a mixture of combustion products, unburned coal seam desorbed gas, underground water vapor and air. Analyzing such mixed gas cannot determine the specific source horizon of the marker gas (such as high-concentration CO), resulting in ambiguity of the fire source positioning (vertical and horizontal), and even misleading conclusions.

[0007] Given the shortcomings of existing technologies, there is an urgent need for a new type of underground gas sampling device for coalfield fire areas that is multifunctional, adjustable, and resistant to high temperatures. This device should be able to achieve in-situ isolation of the target strata within the borehole and directly and rapidly collect the most representative original gas from the fractures or pores of the target coal and rock, thereby improving the accuracy of gas samples. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a multifunctional adjustable underground gas sampling device for coalfields, used to improve the accuracy of gas samples.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: A multifunctional adjustable underground gas sampling device for coalfields includes a drilling rig and a sampling cylinder. The drilling rig and the sampling cylinder are detachably connected. The drilling rig is used to drill a hole in the ground at the target stratum and to lower the sampling cylinder to the target stratum after drilling is completed. A sampling channel is provided inside the sampling cylinder, and a sampling chamber is connected to the bottom of the sampling channel. Packers are symmetrically arranged at the top and bottom of the sampling chamber. The packers are used to form a sealing ring between the sampling cylinder and the borehole wall after the sampling chamber reaches the target stratum.

[0010] The sampling channel is also connected to a negative pressure collection mechanism at the end away from the sampling chamber. The negative pressure collection mechanism is used to generate negative pressure in the sampling channel and store the collected gas.

[0011] The technical principles of the above solution are as follows:

[0012] First, using geophysical exploration, temperature monitoring, or existing geological data, the depth of the target stratum (such as a suspected combustion zone, fractured zone, or specific coal seam) to be sampled is determined. Then, using the drilling rig in the device, a borehole is drilled on the surface to reach the target stratum, providing a pathway for subsequent sampling.

[0013] After drilling is completed, the drill bit and other drilling tools are replaced with a sampling tube. Using the drilling rig's hoisting system, the sampling tube is precisely lowered to the predetermined target stratum depth within the borehole, ensuring that the sampling compartment on the sampling tube is aligned with the target coal and rock layer or fracture zone.

[0014] Once the sampling chamber reaches the target layer, the packer is activated. The packers are symmetrically positioned at the top and bottom of the sampling chamber, and their working principle is to use mechanical expansion to make the packing elements fit tightly against the borehole wall.

[0015] In this way, an annular sealing ring is formed at both the upper and lower ends of the sampling chamber, between the outer wall of the sampling cylinder and the borehole wall. These two sealing rings completely and physically isolate the local well section where the target layer is located (i.e., the area corresponding to the sampling chamber) from the other parts of the borehole above and below, creating an independent in-situ sampling space and effectively preventing the longitudinal convection and mixing of gases at different depths caused by the chimney effect due to the temperature gradient within the borehole.

[0016] After sealing and isolation are completed, the negative pressure collection mechanism connected to the sampling channel is activated. This mechanism generates a stable negative pressure (lower than the gas pressure in the pores or fractures of the target coal and rock matrix) within the sampling channel and the isolated sampling chamber. Driven by the pressure difference, the original gas contained in the micropores and fracture network of the target coal and rock matrix is ​​directly and rapidly drawn into the sampling chamber and transported upwards through the sampling channel. Due to the presence of the sealing ring, the collected gas strictly originates from the isolated target layer, avoiding contamination from upper air infiltration, lower gas upflow, or mixed gas in the wellbore. The extracted gas is stored in a dedicated gas storage container within the negative pressure collection mechanism under negative pressure.

[0017] The above approach has the following beneficial effects:

[0018] 1. This method, through the physical seal formed by upper and lower packers, precisely isolates the target stratum and directly extracts gas from the fractures or pores of the coal and rock layers, ensuring the uniqueness and accuracy of the gas sample's spatial source. This solves the problems of gas mixing and unclear sources in traditional methods, providing direct and reliable evidence for accurately determining the vertical location of the ignition source and identifying gas-conducting fracture channels.

[0019] 2. This method avoids the diffusion, dilution, adsorption, oxidation, and mixing with gases from other formations during long-distance gas transport (surface sampling) or forced convection within the wellbore (drilling extraction). The collected gas best reflects the original chemical state of the target formation, ensuring the accuracy and effectiveness of key indicators such as the concentration and isotopic characteristics of critical marker gases (e.g., CO, olefin / alkane ratio), greatly enhancing the reliability of using gas information to derive ignition temperature and determine the combustion stage.

[0020] 3. In this solution, the device is detachably connected to conventional drilling rigs, utilizing existing drilling equipment to complete drilling and sample cartridge deployment, eliminating the need for entirely special drilling processes and facilitating on-site implementation. The sample cartridge has a high degree of structural integration, with streamlined processes for deployment, sealing, sampling, and retrieval, improving operational efficiency.

[0021] Furthermore, the packer includes an annular movable cavity formed within the sampling tube. The movable cavity is connected to the outside on the side near the sampling chamber. Several first adjustment slots are circumferentially formed within the movable cavity. Each of the first adjustment slots is slidably connected to a first adjustment rod. Each first adjustment rod is rotatably connected to several connecting rods at one end near the movable cavity. Each connecting rod is rotatably connected to a ring block at the other end. The ring blocks slide against the inner wall of the movable cavity. When all the ring blocks overlap, they together form a complete ring. Each of the first adjustment slots is connected to a first pneumatic component at the end away from the movable cavity. The first pneumatic component is used to control the air pressure changes within the first adjustment slots.

[0022] When positive pressure is generated in the first adjusting groove, the positive pressure pushes the first adjusting rod to move. The first adjusting rod pushes the ring block towards the sampling chamber until it contacts the inner wall of the moving cavity. Then, the first adjusting rod drives the connecting rod to deflect, and the connecting rod pushes the ring block to move outward along the inner wall of the moving cavity.

[0023] Beneficial effects: Before the sampling cylinder is lowered to the target layer, the first pneumatic component maintains the first adjustment groove at normal or negative pressure. At this time, under the action of the linkage mechanism, all ring blocks radially contract and axially stagger into the annular movable cavity. In this mechanism, all ring blocks are divided into two groups. The two groups of ring blocks interlock, making the overall outer diameter of the packer basically consistent with the outer diameter of the sampling cylinder, minimizing resistance and the risk of stuck drill during the lowering process.

[0024] Once the sampling chamber reaches the target stratum, the first pneumatic assembly injects gas into the first adjusting groove corresponding to the first group of ring blocks, generating positive pressure. This positive pressure pushes all the first adjusting rods in that group to slide synchronously towards the sampling chamber (i.e., outwards). The first adjusting rods drive the connecting rods and the entire ring block to move axially until the ring block contacts the inner wall of the movable cavity (i.e., the predetermined stroke limit surface). This step completes the precise transfer of the ring block assembly from its storage position to the expansion starting point, preparing for radial expansion.

[0025] As the first adjusting rod continues to move forward under air pressure, the linkage mechanism undergoes a motion transformation because the ring block is already confined by the inner wall of the movable cavity. The axial thrust of the first adjusting rod is converted into a torque through the connecting rod, forcing the ring block to rotate radially outward around the hinge point. Thus, the first set of ring blocks, like petals, synchronously expands outward along the guide rails on the inner wall of the movable cavity until they tightly abut against the borehole wall, forming several spaced, solid initial support points, constituting the primary skeleton of the sealing ring.

[0026] Next, the first pneumatic component injects gas into the first adjustment groove corresponding to the second set of ring blocks, driving it to perform the same axial propulsion-radial expansion process. The unique design of the second set of ring blocks allows it to precisely fill the pre-reserved gaps between the first set of ring blocks during expansion. The two sets of ring blocks finally fit seamlessly together at the bore wall, forming a continuous and complete sealing ring.

[0027] In this design, the annular block is completely housed within the sampling cylinder body in its retracted state, with no protruding parts. This significantly reduces the risk of device damage or accidental sealing due to scraping the well wall during descent, ensuring the device can safely and smoothly reach the deep target layer. Unlike inflatable capsules that rely entirely on continuous gas pressure, this design allows the linkage mechanism to reach or nearly reach a self-locking state, or require only a lower pressure, after the annular block is fully deployed and presses against the borehole wall. This mechanical locking characteristic significantly reduces dependence on continuous gas pressure, resulting in a more stable seal, especially suitable for high-temperature environments, and avoiding the drawbacks of rubber capsules such as easy aging and pressure leakage. The annular block and linkage mechanism can be made of high-temperature resistant and corrosion-resistant metal materials, offering a longer service life and better resistance to wear and high-temperature deformation compared to rubber capsules, making them more suitable for repeated use in harsh coalfield fire environments.

[0028] Furthermore, a filter cylinder is installed on the outside of the sampling chamber, and several through holes are opened on the filter cylinder.

[0029] Beneficial effects: In coal and rock fissures or pores within the target strata of coalfield fire zones, in addition to the target gas, there is often a mixture of fine coal dust and rock debris generated by high temperatures and stress changes, as well as water droplets or aerosols formed by the condensation of underground water vapor. The filter cartridge, as the first physical barrier for the gas entering the sampling chamber, with its through-hole design (different pore sizes and shapes can be selected as needed, or filter screens or membranes can be added), can effectively intercept and filter these solid particles and liquid water droplets.

[0030] Furthermore, spiral guide rails are installed at both the end of the sampling channel near the sampling chamber and inside the sampling chamber.

[0031] Beneficial effects: Although the outer filter cartridge performs preliminary filtration, extremely fine atomized droplets or ultrafine particles may still enter with the gas. The spiral guide rail forces the gas to rotate along the spiral path, generating significant centrifugal force. Under centrifugal force, liquid droplets and solid particles with a density greater than that of gas are thrown towards the inner wall of the sampling channel or sampling chamber. The spiral structure significantly extends the gas flow path within a limited space. This not only increases the time impurities are subjected to centrifugal force but also improves separation efficiency.

[0032] Furthermore, a cooling pipe is also installed inside the sampling channel. The cooling pipe is laid out along the outside of the sampling channel, and a circulating cooling mechanism is connected to both ends of the cooling pipe. The circulating cooling mechanism is used to circulate and deliver cold medium into the cooling pipe.

[0033] Beneficial effects: The high-temperature gas extracted from the borehole can cause extremely high temperatures on the upper part of the sampling cylinder and the surface of the outlet pipe, posing a risk of burns to operators. By forcibly cooling this section of the channel, the surface temperature of the exposed parts of the device can be effectively reduced, significantly improving the safety of on-site operations.

[0034] During the ascent of high-temperature in-situ gases, if they are slowly cooled naturally, some unstable components (such as some olefins and long-chain alkanes) may continue to undergo pyrolysis, oxidation, or catalytic reactions within the pipeline, altering their original concentration ratios. The cooling system, by rapidly cooling the gas to near-surface ambient temperature or a set safe temperature in a specific section of the sampling channel, effectively freezes the gas's chemical state, minimizing secondary chemical reactions that may occur during the critical period from sampling to storage. This ensures the originality of gas samples (especially indicative gases used to determine ignition source temperature and combustion stage) and the authenticity and accuracy of analytical data.

[0035] Furthermore, a central column is fixedly connected inside the sampling cylinder. The central column is arranged along the axis of the sampling chamber. A sliding groove is opened inside the central column, and a sliding rod is slidably fitted inside the sliding groove. A cleaning cylinder is slidably connected inside the filter cylinder. Several support rods are fixedly connected between the cleaning cylinder and the sliding rod, and the support rods are slidably connected to the central column. A power mechanism is set at the end of the sliding groove away from the sampling chamber. The power mechanism is used to drive the sliding rod to move back and forth.

[0036] Beneficial Effects: When sampling in high-temperature, fractured coal and rock formations, the through-holes of the filter cartridge are easily and rapidly clogged by fine coal dust and rock debris, leading to a sharp increase in air intake resistance and a decrease or even interruption of sampling flow. Traditional solutions require drilling and manual disassembly and cleaning, resulting in frequent operation interruptions and extremely low efficiency. This design uses a power mechanism to drive a slide bar, which moves the cleaning cartridge back and forth inside the filter cartridge, directly scraping or flushing away the blockages adhering to the inner surface of the filter cartridge. This achieves online cleaning without drilling or disassembly, and can be triggered multiple times during a single well run, ensuring long-term, continuous, and stable gas sampling capabilities.

[0037] Furthermore, the power mechanism includes a piston chamber located inside the sampling cylinder, a heat exchange layer at the bottom of the piston chamber, and the sampling channel passing through the heat exchange layer; a heat dissipation mechanism is located at the top of the piston chamber, and the heat dissipation mechanism is connected to the cooling pipe.

[0038] A displacement piston is slidably fitted inside the piston chamber, and a central column passes through the displacement piston. The displacement piston and the central column are slidably fitted together, and a sliding rod is fixedly connected to the displacement piston.

[0039] Beneficial effects: This approach abandons the traditional reliance on external electric, hydraulic, or pneumatic power sources, instead directly capturing and utilizing the thermal energy contained in the high-temperature gas flow inherent in sampling operations. The heat is efficiently transferred from the gas to the working fluid within the piston chamber via a heat exchange layer, where the heated fluid expands and performs work, driving the displacement piston. This not only completely eliminates dependence on complex external energy supplies and simplifies ground support equipment, but also achieves closed-loop energy utilization within the device, converting heat pollution into power, and significantly improving the overall system's integration, self-sufficiency, and convenience.

[0040] Combustible and explosive gas mixtures may exist within boreholes in coalfield fire zones. Introducing electric motors or high-voltage electrical components poses a potential risk of electrical spark ignition. This design employs a purely thermo-mechanical drive principle, with no electrical components or external power supply required, making it an intrinsically safe design. Its power source (high-temperature gas) and transmission mechanism are completely enclosed within a pressure-resistant metal chamber, fundamentally eliminating safety accidents caused by the power system. This design is particularly well-suited to the extreme explosion-proof safety requirements of the high-risk environments in underground coal mines and fire zones.

[0041] The driving force of this system is directly proportional to the temperature of the sampled gas. When the ignition source is active and the gas temperature is high, the working fluid in the piston chamber expands more violently, generating a greater driving force and resulting in faster and more frequent cleaning strokes. This is precisely when more intensive cleaning is needed—because high temperatures are often accompanied by more intense thermal fracturing of coal and rock, generating more dust and making the filter cartridge more prone to clogging. Conversely, at lower temperatures, the cleaning action is correspondingly gentler. This adaptive characteristic of being stronger when needed and weaker when needed allows the cleaning work to be perfectly matched with the actual risk of clogging, achieving intelligent and optimized operation.

[0042] Furthermore, an impeller is rotatably connected inside the sampling channel, and a turntable is coaxially fixedly connected to the back side of the impeller. The turntable is rotatably connected to the inner wall of the sampling channel, and a second drive shaft is eccentrically rotatably connected to the turntable. The other end of the second drive shaft is rotatably connected to a first drive shaft, and the other end of the first drive shaft extends into the piston chamber and is fixedly connected to the displacement piston.

[0043] Beneficial Effects: In the initial stage of sampling operations, especially for target layers with relatively low temperatures (such as the pre-combustion zone, the edge of thermal anomalies) or when the device has just been lowered, the temperature of the gas flowing through the sampling channel may not be sufficient to quickly heat the working fluid in the piston chamber to the effective working temperature, resulting in preheating lag in the pure heat engine drive mode. In this design, as soon as the negative pressure collection mechanism is activated, generating suction airflow, the airflow will immediately drive the impeller to rotate, regardless of the gas temperature. This rotational motion is efficiently converted into reciprocating pulling or pushing on the first drive shaft through the turntable and the second drive shaft, thereby directly and instantly driving the displacement piston to start working, reducing the preheating time of the heat engine system. At the same time, the reciprocating movement of the displacement piston forms an efficient bidirectional energy utilization and positive feedback loop:

[0044] Airflow-driven cleaning (forward): The sampled airflow drives the impeller, providing instant mechanical power to the cleaning system.

[0045] Enhanced thermal engine drive (main drive): As high-temperature gas continues to flow through, the thermal engine system gradually reaches its optimal operating state, providing a more powerful main driving force.

[0046] Cleaning-Assisted Sampling (Reverse Feedback): Crucially, when the heat-engine-driven displacement piston reciprocates powerfully, its power is transmitted back to the impeller via the first and second drive shafts and the turntable, accelerating or assisting the impeller's rotation. This is equivalent to embedding a miniature gas booster or rectifier driven by the cleaning system within the sampling channel. The impeller's auxiliary rotation further optimizes the flow field, reduces airflow resistance, and enhances the local suction effect to some extent, thereby improving sampling efficiency and flow stability, achieving a synergistic gain between cleaning action and sampling performance.

[0047] Furthermore, elastic sealing gaskets are installed at the points where the active cavity connects to the outside.

[0048] Beneficial effects: The soft properties of the elastic sealing gasket allow it to conform to the shape of the ring block root, providing a smooth transition guide for the radial movement of the ring block and reducing the risk of friction and jamming. After the ring block is fully unfolded, it can fill the small irregular gaps that may exist between its root and the cavity opening, helping the ring block assembly to form a more continuous and flat support back, indirectly improving its overall fit with the hole wall.

[0049] Furthermore, a filter element is installed inside the sampling channel to adsorb impurities.

[0050] Beneficial effects: The filter element is located at the very end of the sampling process, before the gas enters the negative pressure collection mechanism (gas storage unit) or is directly connected to the analysis port. It can capture any particulate matter, aerosols or corrosive gas components that have not been completely removed upstream.

[0051] The filter element and the preceding device design constitute a logically rigorous, step-by-step purification system:

[0052] Primary physical interception (filter cartridge): mainly removes solid particles, rock debris, and most liquid droplets.

[0053] Two-stage centrifugal separation and condensation (spiral guide rail + cooling pipe): fine particles are further removed by centrifugal force, and most of the water vapor is removed by condensation.

[0054] Three-stage deep adsorption (filter cartridge): removes residual trace moisture and specific interfering gases through final chemical adsorption. Attached Figure Description

[0055] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of the multifunctional adjustable underground gas sampling device for coalfields of the present invention;

[0056] Figure 2 for Figure 1 A schematic diagram of the internal structure of the sampling tube in an embodiment of a multifunctional adjustable underground gas sampling device for coalfields;

[0057] Figure 3 for Figure 2 Enlarged diagram of part A in the middle;

[0058] Figure 4 for Figure 2 Enlarged diagram of section B;

[0059] Figure 5 for Figure 2 This is an enlarged schematic diagram of part C.

[0060] The reference numerals in the accompanying drawings include: 1. Drilling rig; 2. Sampling cylinder; 201. Sampling channel; 202. First adjusting groove; 203. First adjusting rod; 204. Second adjusting groove; 205. Second adjusting rod; 206. Cooling pipe; 207. Piston chamber; 208. Displacement piston; 209. Central column; 210. Slide groove; 211. Slide rod; 212. First drive shaft; 213. Second drive shaft; 214. Turntable; 215. Impeller; 216. Movable cavity; 217. Ring block; 218. Connecting rod; 219. Elastic sealing gasket; 220. Spiral guide rail; 221. Filter cylinder; 222. Cleaning cylinder; 223. Support rod; 224. Through hole. Detailed Implementation

[0061] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. 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.

[0062] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0063] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0064] The following detailed description illustrates the specific implementation method:

[0065] Example:

[0066] As attached Figure 1 - Appendix Figure 5 The diagram illustrates a multifunctional adjustable underground gas sampling device for coalfields, comprising a drilling rig 1 and a sampling cylinder 2. The drilling rig 1 and sampling cylinder 2 are detachably connected. The drilling rig 1 is used to drill holes in the target stratum and, after drilling, to lower the sampling cylinder 2 to the target stratum. Specifically, the drilling rig 1 mainly consists of the following components: a frame, a power system, a hoisting system (responsible for raising and lowering the drilling tools (drill rods, drill collars, etc.), a rotation system (driving the drill rods and drill bits to rotate), and a control system. This part is prior art and will not be elaborated upon in this paper.

[0067] The sampling tube 2 has a sampling channel 201, which is combined with the attached Figure 2 and attached Figure 5 As shown, the bottom of the sampling channel 201 is connected to a sampling chamber, and a filter cylinder 221 is installed on the outside of the sampling chamber. The filter cylinder 221 is welded and fixed to the sampling cylinder 2, and several through holes 224 are opened on the filter cylinder 221.

[0068] Preferably, a filter element (not shown in the figure) is also installed in the sampling channel 201. In this embodiment, the filter element is mainly located at the end of the sampling channel 201 away from the sampling chamber (i.e., the outlet). The filter element is used to adsorb impurities, such as water vapor and particulate matter. Operators can ensure the filtration effect by replacing the filter element regularly.

[0069] Preferably, a spiral guide rail 220 is welded and fixed to both the sampling channel 201 near the sampling chamber and inside the sampling chamber. The spiral guide rail 220 transforms the disordered turbulent flow into an ordered laminar or quasi-laminar flow that rotates along a predetermined spiral.

[0070] Preferably, a cooling pipe 206 is also provided inside the sampling channel 201. The cooling pipe 206 is arranged along the outside of the sampling channel 201. Specifically, in this embodiment, the cooling pipe 206 is mainly concentrated in the middle section and near the outlet section of the sampling channel 201. Both ends of the cooling pipe 206 are connected to a circulating cooling mechanism, which is used to circulate and deliver cold medium into the cooling pipe 206. Preferably, in this embodiment, the circulating cooling mechanism adopts existing related air-cooling technology, such as a circulating cooling mechanism mainly composed of a fan, compressor, condenser, throttling expansion device, evaporator, and pipeline (existing technology, not described in detail here). The circulating cooling mechanism continuously delivers cold air into the cooling pipe 206 to achieve cooling.

[0071] Preferably, a central column 209 is integrated inside the sampling cylinder 2. The central column 209 is arranged along the axis of the sampling chamber. A sliding groove 210 is formed inside the central column 209, and a sliding rod 211 is slidably fitted inside the sliding groove 210. A cleaning cylinder 222 is slidably connected to the inside of the filter cylinder 221. Several support rods 223 are fixedly connected between the cleaning cylinder 222 and the sliding rod 211. The support rods 223 are slidably connected to the central column 209. Specifically, in this embodiment, a groove for sliding of the support rods 223 is formed on the side of the central column 209. The support rods 223 slide freely by cooperating with the groove. A power mechanism is provided at the end of the sliding groove 210 away from the sampling chamber. The power mechanism is used to drive the sliding rod 211 to move back and forth. Specifically, in conjunction with the attached... Figure 2 and attached Figure 4 As shown, the power mechanism includes a piston chamber 207 located inside the sampling cylinder 2. A heat exchange layer (not shown in the figure) is embedded at the bottom of the piston chamber 207, and the sampling channel 201 passes through the heat exchange layer. A heat dissipation mechanism is provided at the top of the piston chamber 207. The heat dissipation mechanism adopts a spiral tube, which surrounds the top of the piston chamber 207. Both ends of the spiral tube are connected to the cooling pipe 206. Cold air enters one end of the spiral tube through the cooling pipe 206, then flows into the cooling pipe 206 from the other end of the spiral tube, and then flows back into the pipeline of the circulating cooling mechanism from the cooling pipe 206. A displacement piston 208 is slidably fitted inside the piston chamber 207. A central column 209 passes through the displacement piston 208, and the displacement piston 208 and the central column 209 are slidably fitted. A sliding rod 211 is fixedly connected to the displacement piston 208. Specifically, a groove is also provided between the displacement piston 208 and the sliding rod 211. The displacement piston 208 and the sliding rod 211 are rigidly connected by a slider. The slider is slidably fitted with the groove, thereby realizing the synchronous movement of the displacement piston 208 and the sliding rod 211.

[0072] Preferred, combined with appendix Figure 4As shown, an impeller 215 is rotatably connected inside the sampling channel 201. A turntable 214 is coaxially fixedly connected to the back side of the impeller 215. The turntable 214 is rotatably connected to the inner wall of the sampling channel 201. A second drive shaft 213 is eccentrically rotatably connected to the side of the turntable 214 away from the impeller 215. A first drive shaft 212 is rotatably connected to the other end of the second drive shaft 213. The other end of the first drive shaft 212 extends into the piston chamber 207 and is fixedly connected to the displacement piston 208.

[0073] Packers are symmetrically arranged at the top and bottom of the sampling chamber. These packers form a sealing ring between the sampling cylinder 2 and the borehole wall after the sampling chamber reaches the target stratum. Specifically, refer to the attached... Figure 5 As shown, the packer located above includes an annular movable cavity 216 opened inside the sampling cylinder 2. The movable cavity 216 is located directly above the sampling chamber. The side of the movable cavity 216 near the sampling chamber is connected to the outside, that is, an annular opening is opened in the side wall direction of the movable cavity 216. Several first adjustment grooves 202 are opened circumferentially inside the movable cavity 216. A first adjustment rod 203 is slidably connected in each of the first adjustment grooves 202. Several connecting rods 218 are rotatably connected to the end of the first adjustment rod 203 near the movable cavity 216. A ring block 217 is rotatably connected to the other end of the connecting rod 218. The ring block 217 slides in cooperation with the inner wall of the movable cavity 216. When all the ring blocks 217 overlap, the ring blocks 217 together form a complete ring. The end of the first adjustment groove 202 away from the movable cavity 216 is connected to a first pneumatic component. The first pneumatic component is used to control the air pressure change in the first adjustment groove 202. Specifically, the first pneumatic component includes a bidirectional pump, the output end of which is connected to each of the first regulating slots 202 via a conduit.

[0074] When the first adjusting groove 202 is under positive pressure, the positive pressure pushes the first adjusting rod 203 to move. The first adjusting rod 203 pushes the ring block 217 toward the sampling chamber until it comes into contact with the inner wall of the movable cavity 216. Then, the first adjusting rod 203 drives the connecting rod 218 to deflect, and the connecting rod 218 pushes the ring block 217 to move outward along the inner wall of the movable cavity 216.

[0075] Specifically, in this embodiment, the ring blocks 217 located on the same side can be divided into two groups. The two groups of ring blocks 217 radially contract and axially stagger and are housed in the movable cavity 216. After the two groups of ring blocks 217 are unfolded, they can just match and fill the reserved gaps after unfolding. (See attached diagram) Figure 5 As shown in the figure, the shaded ring block 217 represents the retracted state, while the blank ring block 217 represents the unfolded state. A reversing valve connects the bidirectional pump to each of the first regulating slots 202, enabling alternating control of the two sets of ring blocks 217.

[0076] The lower packer has the same structure as the upper packer, meaning it also includes an annular movable cavity 216 located directly below the sampling chamber 2 within the sampling tube 2. This movable cavity 216 also has several second adjusting grooves 204 circumferentially arranged within it. Each second adjusting groove 204 is slidably connected to a second adjusting rod 205. Each second adjusting rod 205 near the movable cavity 216 is rotatably connected to several connecting rods 218, and the other end of each connecting rod 218 is rotatably connected to a ring block 217. The ring blocks 217 also slide against the inner wall of the movable cavity 216. When all the ring blocks 217 overlap, they form a complete ring. The end of each second adjusting groove 204 away from the movable cavity 216 is connected to a second pneumatic assembly, which controls the air pressure changes within the second adjusting groove 204. The second pneumatic assembly also uses a bidirectional pump, and its output end is connected to each of the second adjusting grooves 204 via a conduit. The packer located below differs from the packer located above only in that the second adjusting groove 204 is opened inside the central column 209, the shape and size of the movable cavity 216 are different, and the length of the connecting rod 218 is different.

[0077] Preferably, in this embodiment, an elastic sealing gasket 219 is fixedly connected to the connection between the movable cavity 216 and the outside. The elastic sealing gasket 219 is made of a high-temperature resistant material, such as fluororubber.

[0078] The sampling channel 201, at the end furthest from the sampling chamber, is also connected to a negative pressure collection mechanism. This mechanism generates negative pressure within the sampling channel 201 and stores the collected gas. Specifically, the negative pressure collection mechanism includes a negative pressure pump and a gas storage tank (not shown in the figure). The gas storage tank is connected to the sampling channel 201 via a gas pipe, and the negative pressure pump is connected to the connection path between the gas storage tank and the sampling channel 201.

[0079] Preferably, a guide channel (not shown in the figure) is also provided on the side wall of the sampling channel 201. The guide channel is arranged in the area of ​​the sampling channel 201 through which the cooling pipe 206 passes. The bottom of the guide channel is also connected to a collection tank, which is used to temporarily store the moisture generated after the sampled gas is condensed.

[0080] The specific implementation process is as follows:

[0081] Based on geological exploration data and fire zone detection data, determine the depth of the target sampling layer (such as a suspected combustion zone or a specific coal seam). Using the drilling rig 1 provided with the equipment, drill a vertical borehole at the surface location corresponding to the target layer, reaching and slightly exceeding the bottom of the target layer. After drilling is completed, remove the drill bit and other drilling tools.

[0082] The sampling tube 2 is installed onto the hoisting system of the drilling rig 1 via its detachable interface at the top. Then, the hoisting system is operated to smoothly lower the sampling tube 2 into the borehole. Precise positioning is achieved using the depth measuring device on the drilling rig 1, ensuring that the sampling compartment of the sampling tube 2 (i.e., the section between the upper and lower packers) is perfectly aligned with the target coal and rock layer or fracture zone.

[0083] Once the sampling chamber reaches the predetermined depth, the sealing procedure is initiated.

[0084] Upper packer operation: First, the first pneumatic assembly (bidirectional pump) connected to the upper packer is activated. This pump preferentially injects gas into the first adjusting groove 202 corresponding to the first set of ring blocks 217, generating positive pressure. The positive pressure pushes the first adjusting rod 203 to slide outward, driving the connecting rod 218 mechanism connected to it, causing the set of ring blocks 217 to move axially first, and then expand radially outward, abutting against the borehole wall to form a preliminary support frame.

[0085] Next, the first pneumatic component injects air into the first adjustment groove 202 corresponding to the second set of ring blocks 217, driving the ring blocks 217 to repeat the above process. After expansion, the ring blocks 217 precisely fill the gaps between the first set of ring blocks 217, together forming a complete upper sealing ring. The elastic sealing gasket 219 at the opening of the movable cavity 216 deforms with the movement of the ring blocks 217 during this process, effectively isolating external contaminants while filling the gaps between the ring blocks 217 and between the ring blocks 217 and the hole wall.

[0086] The lower packer operates synchronously / sequentially: Following the same principle as the upper packer, the second pneumatic assembly is activated, driving the lower packer's ring blocks 217 to unfold sequentially, forming another complete sealing ring below the sampling chamber. At this point, the upper and lower packers form two robust sealing rings between the upper and lower ends of the sampling chamber and the borehole wall, completely isolating the target stratum and creating an independent, sealed in-situ sampling space.

[0087] After sealing is completed, the negative pressure collection mechanism is activated. The negative pressure pump starts working, establishing negative pressure in sampling channel 201 and the isolated sampling chamber.

[0088] Gas intake and primary filtration: Under negative pressure, gas from the target coal and rock formation is drawn in through the through-holes 224 on the filter cartridge 221. The filter cartridge 221 effectively blocks large particulate impurities such as coal dust and rock fragments.

[0089] Gas enters the sampling chamber and channel inlet section, where the internal spiral guide rail 220 causes it to rotate and flow, generating centrifugal force to further separate fine particles. At the same time, the cleaning system starts working.

[0090] The gas continues to rise, flowing through the channel section enclosed by cooling pipe 206. The circulating cooling mechanism continuously supplies a cold medium (such as cold air) into the cooling pipe 206, forcibly cooling the gas. A large amount of water vapor in the gas condenses here, and the condensate is collected in the collection tank along the guide groove on the side wall of the sampling channel 201 for temporary storage.

[0091] After being cooled and dried, the gas passes through a filter element installed near the channel outlet. The filter element deeply dries the gas and adsorbs any remaining trace interfering substances. Finally, the resulting high-purity, dry gas is transported to a storage tank for storage, completing one sampling operation.

[0092] The cleaning system operates automatically during the sampling process, powered by a dual-mode drive:

[0093] Once the negative pressure pump starts and generates airflow, the impeller 215 is immediately driven to rotate. The rotation of the impeller 215 is converted into reciprocating motion via the turntable 214 and the second drive shaft 213. This reciprocating motion directly drives the displacement piston 208 and the slide rod 211 to generate initial displacement via the first drive shaft 212, thereby driving the cleaning cartridge 222 to slide inside the filter cartridge 221 for the first cleaning. This mechanism ensures that the anti-clogging operation begins before the gas temperature rises.

[0094] As the high-temperature gas flows through the heat exchange layer at the bottom of the piston chamber 207, heat is transferred to the working fluid inside the chamber. The working fluid expands due to heat, pushing the displacement piston 208 to perform a larger reciprocating motion, becoming the main driving force for the cleaning operation. The other side of the piston is cooled through a heat dissipation mechanism (a spiral tube connected to the cooling pipe 206), completing the thermodynamic cycle. This process continues, and the cleaning frequency adapts to the gas temperature (the higher the temperature, the more frequent the cleaning).

[0095] The reciprocating motion of the displacement piston 208 also reacts to the impeller 215 through the drive shaft, assisting its rotation and optimizing the airflow in the channel to a certain extent, forming a positive interaction between cleaning and sampling.

[0096] After completing the designated sampling task: First, stop the negative pressure collection mechanism. Control the first and second pneumatic components to change the adjustment grooves of the upper and lower packers to negative or normal pressure. Under the action of the connecting rod 218 mechanism, the ring block 217 radially contracts and axially moves back into the movable cavity 216 for staggered storage, disengaging from contact with the borehole wall, thus releasing the seal. Operate the hoisting system of the drilling rig 1 to lift the entire sampling cylinder 2 out of the borehole.

[0097] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multifunctional adjustable underground gas sampling device for coalfields, comprising a drilling rig (1) and a sampling tube (2), wherein the drilling rig (1) and the sampling tube (2) are detachably connected, the drilling rig (1) being used to drill a hole in the ground at the target stratum and to lower the sampling tube (2) to the target stratum after drilling is completed; characterized in that, A sampling channel (201) is provided inside the sampling tube (2). The bottom of the sampling channel (201) is connected to the sampling chamber. Packers are symmetrically arranged at the top and bottom of the sampling chamber. The packers are used to form a sealing ring between the sampling tube (2) and the hole wall after the sampling chamber reaches the target layer. The sampling channel (201) is connected to a negative pressure collection mechanism at the end away from the sampling chamber. The negative pressure collection mechanism is used to generate negative pressure in the sampling channel (201) and store the collected gas.

2. The multifunctional adjustable coalfield underground gas sampling device according to claim 1, characterized in that, The packer includes an annular movable cavity (216) opened inside the sampling tube (2). The movable cavity (216) is connected to the outside on the side near the sampling chamber. Several first adjustment grooves (202) are opened circumferentially inside the movable cavity (216). A first adjustment rod (203) is slidably connected in each of the first adjustment grooves (202). Several connecting rods (218) are rotatably connected to one end of the first adjustment rod (203) near the movable cavity (216). A ring block (217) is rotatably connected to the other end of the connecting rod (218). The ring block (217) slides with the inner wall of the movable cavity (216). When all the ring blocks (217) overlap, the ring blocks (217) together form a complete ring. A first pneumatic component is connected to the end of the first adjustment groove (202) away from the movable cavity (216). The first pneumatic component is used to control the air pressure change in the first adjustment groove (202). When the first adjustment groove (202) is under positive pressure, the positive pressure pushes the first adjustment rod (203) to move. The first adjustment rod (203) pushes the ring block (217) towards the sampling chamber until it comes into contact with the inner wall of the active cavity (216). Then, the first adjustment rod (203) drives the connecting rod (218) to deflect. The connecting rod (218) pushes the ring block (217) to move outward along the inner wall of the active cavity (216).

3. The multifunctional adjustable coalfield underground gas sampling device according to claim 2, characterized in that, A filter cartridge (221) is installed on the outside of the sampling chamber, and several through holes (224) are opened on the filter cartridge (221).

4. The multifunctional adjustable coalfield underground gas sampling device according to claim 3, characterized in that, The sampling channel (201) is equipped with a spiral guide rail (220) at one end near the sampling chamber and inside the sampling chamber.

5. The multifunctional adjustable coalfield underground gas sampling device according to claim 4, characterized in that, A cooling pipe (206) is also installed in the sampling channel (201). The cooling pipe (206) is installed along the outside of the sampling channel (201). Both ends of the cooling pipe (206) are connected to a circulating cooling mechanism, which is used to circulate and deliver cold medium into the cooling pipe (206).

6. The multifunctional adjustable coalfield underground gas sampling device according to claim 5, characterized in that, A central column (209) is fixedly connected inside the sampling cylinder (2). The central column (209) is arranged along the axis of the sampling chamber. A sliding groove (210) is opened inside the central column (209). A sliding rod (211) is slidably fitted inside the sliding groove (210). A cleaning cylinder (222) is slidably connected inside the filter cylinder (221). Several support rods (223) are fixedly connected between the cleaning cylinder (222) and the sliding rod (211). The support rods (223) are slidably connected to the central column (209). A power mechanism is provided at the end of the sliding groove (210) away from the sampling chamber. The power mechanism is used to drive the sliding rod (211) to move back and forth.

7. The multifunctional adjustable coalfield underground gas sampling device according to claim 6, characterized in that, The power mechanism includes a piston chamber (207) opened in the sampling cylinder (2), a heat exchange layer is provided at the bottom of the piston chamber (207), and the sampling channel (201) passes through the heat exchange layer; a heat dissipation mechanism is provided at the top of the piston chamber (207), and the heat dissipation mechanism is connected to the cooling pipe (206); The piston chamber (207) has a sliding fit with a displacement piston (208), and the central column (209) passes through the displacement piston (208). The displacement piston (208) and the central column (209) are in sliding fit, and the slide rod (211) is fixedly connected to the displacement piston (208).

8. The multifunctional adjustable coalfield underground gas sampling device according to claim 7, characterized in that, An impeller (215) is rotatably connected inside the sampling channel (201). A turntable (214) is coaxially fixedly connected to the back side of the impeller (215). The turntable (214) is rotatably connected to the inner wall of the sampling channel (201). A second drive shaft (213) is eccentrically rotatably connected to the turntable (214). A first drive shaft (212) is rotatably connected to the other end of the second drive shaft (213). The other end of the first drive shaft (212) extends into the piston chamber (207) and is fixedly connected to the displacement piston (208).

9. The multifunctional adjustable coalfield underground gas sampling device according to claim 8, characterized in that, An elastic sealing gasket (219) is also provided at the connection between the movable cavity (216) and the outside.

10. The multifunctional adjustable coalfield underground gas sampling device according to claim 9, characterized in that, The sampling channel (201) is also equipped with a filter element, which is used to adsorb impurities.

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