A coalbed methane collection device

Abstract

This utility model discloses a coalbed methane collection device, including a tank support base mounted on the ground. A gas gathering and transportation tank is installed on the tank support base. A gas gathering pipe partially extending into the ground is connected below the gas gathering and transportation tank. A first tapered section is arranged on the gas gathering and transportation pipe near the gas gathering and transportation tank. A first throat stabilizing section is connected below the first tapered section. A first tapered amplifying and pressurizing section is connected below the first throat stabilizing section. A second tapered section is connected to the first tapered section. A second throat stabilizing section is connected below the second tapered section. A second tapered amplifying and pressurizing section is connected to the second throat stabilizing section. The above structure abandons the straight pipe or single tapered pipe structure and adopts a Venturi-like unit with a gentler pressure drop gradient. Multiple Venturi-like units are integrated in series, allowing the gas flow to pass through multiple throat stabilizing sections in stages for accelerated flow, effectively suppressing sudden changes in local pressure drop.

Description

Technical Field

[0001] This utility model relates to the technical field of coalbed methane collection, and specifically to a coalbed methane collection device. Background Technology

[0002] Coalbed methane (CBM) is an unconventional natural gas resource adsorbed and stored within the pores of the coal seam matrix. Its main component is methane, and its calorific value is comparable to that of conventional natural gas. This resource possesses comprehensive value in filling energy supply gaps, reducing the risk of coal mine gas accidents through advanced extraction, and reducing methane greenhouse gas emissions. my country has abundant CBM reserves, and after nearly thirty years of technological accumulation and engineering practice, a preliminary system for its large-scale development and utilization has been established. It should be noted that the methane concentration in CBM obtained through different extraction and drainage methods varies significantly.

[0003] According to the industry literature "Research on Coalbed Methane Extraction and Gathering Technology", there are currently three main technical approaches to coalbed methane development in my country: 1. Surface drilling extraction: Gas is extracted directly from the original coal seam by drilling vertical or horizontal wells, implementing reservoir stimulation (such as fracturing) and depressurization processes. This gas is transported through coalbed methane gathering and transportation tanks, and after purification treatment such as dehydration and desulfurization, it meets the gas quality requirements for pipeline transportation before being introduced into the natural gas pipeline system.

[0004] 2. Underground gas extraction: During the coal mining process or in the goaf, gas is collected through a pre-arranged extraction system (drilling, roadway extraction).

[0005] Abandoned mine extraction: For closed coal mines, the remaining gas resources after the mine closure are extracted by utilizing the remaining shaft engineering or supplementary drilling.

[0006] Currently, the pipelines connecting coalbed methane gas gathering and transportation tanks to the ground generally adopt a simple straight pipe structure, which limits their pumping efficiency. To improve pumping capacity, some companies have designed this pipeline section with a contraction structure, thereby increasing the gas flow rate.

[0007] However, this improvement results in a significant pressure drop between the pipeline inlet and outlet, inducing a sharp increase in fluid resistance. According to fluid mechanics principles, increased pressure drop is accompanied by increased gas velocity. Given that coalbed methane typically contains solid particles such as coal dust and rock fragments, these high-speed flowing particles exert a continuous abrasive effect on the pipe wall (sandblasting effect). This abrasive phenomenon leads to a reduction in pipe wall thickness, significantly increasing the risk of pipeline leakage and even rupture, shortening service life, and driving up maintenance costs.

[0008] Therefore, we provide a coalbed methane collection device to solve the above problems. Utility Model Content

[0009] To address the problems of existing technologies, this invention provides a coalbed methane collection device that abandons straight pipe or single contraction pipe structures. Instead, it employs a Venturi-like unit with a gentler pressure drop gradient, integrating multiple Venturi-like units in series. This allows gas flow to be accelerated in stages through multiple throat-stabilizing pipe sections, effectively suppressing sudden local pressure drop changes. Each unit's gradually increasing pressure pipe section promotes the conversion of gas kinetic energy into static pressure energy through flow channel cross-section expansion, significantly reducing the overall flow resistance of the pipeline system. Simultaneously, the staged flow velocity control mechanism reduces the kinetic energy of solid particles, mitigating their continuous erosive effect on the pipe wall, thereby extending pipeline service life and reducing maintenance costs.

[0010] To achieve the above objectives, this utility model employs a coalbed methane collection device, including a tank support base placed on the ground, a gas gathering and transportation tank installed on the tank support base, a gas gathering pipe partially extending into the ground connected below the gas gathering and transportation tank, a first tapering pipe section provided near the gas gathering and transportation tank on the gas gathering and transportation pipe, a first throat stabilizing pipe section connected below the first tapering pipe section, a first tapering boosting pipe section connected below the first throat stabilizing pipe section, a second tapering pipe section connected to the first tapering boosting pipe section, a second throat stabilizing pipe section connected below the second tapering pipe section, and a second tapering boosting pipe section connected to the second throat stabilizing pipe section.

[0011] As a further optimization of the above scheme, the inlet portion of the first tapered tube section has a different diameter than the outlet portion of the first tapered booster tube section.

[0012] As a further optimization of the above scheme, the inlet portion of the second tapered tube section has a different diameter than the outlet portion of the second tapered booster tube section.

[0013] As a further optimization of the above scheme, the diameter of the inlet portion of the first tapered pipe section is larger than that of the outlet portion of the first tapered booster pipe section.

[0014] As a further optimization of the above scheme, a third tapered pipe section is connected below the second gradually increasing pressure pipe section, a third throat stabilizing pipe section is connected below the third tapered pipe section, and a third gradually increasing pressure pipe section is connected below the third throat stabilizing pipe section.

[0015] As a further optimization of the above scheme, the diameter of the first flared section is the same as that of the second tapered section, and the diameter of the second flared section is the same as that of the third tapered section.

[0016] As a further optimization of the above solution, the gas collection pipe adopts a modular and detachable structure.

[0017] The coalbed methane collection device of this utility model has the following beneficial effects: 1. The coalbed methane collection device of this utility model adopts a multi-stage contraction-diffusivity structure similar to a Venturi tube. It realizes the step-by-step conversion of kinetic energy and pressure energy through a segmented acceleration-deceleration process. Compared with the concentrated high pressure drop generated by a single-stage contraction structure, this scheme disperses the total pressure drop to multiple contraction units and realizes pressure recovery through cross-sectional expansion in each gradually increasing pressure-diffusivity pipe section. This makes the pressure difference between the inlet and outlet of the pipeline uniformly distributed, effectively avoids sudden changes in local resistance, reduces the overall energy loss of the system, and provides a more stable fluid environment for the transportation of high solids coalbed methane. 2. The coalbed methane collection device of this utility model, through the differential diameter design of the throat stabilizing pipe section, ensures that the solid particles carried by the high-speed airflow are only briefly accelerated in the throat stabilizing pipe section, and the flow velocity is sharply reduced after entering the gradually increasing pressure pipe section due to the expansion of the cross section. The kinetic energy of the particles is gradually reduced. This periodic variable speed flow changes the impact of coal powder and rock debris on the pipe wall from continuous high-intensity abrasion to intermittent low-intensity scouring, which significantly reduces the abrasion rate per unit pipe section. Referring to the following description and accompanying drawings, specific embodiments of the present invention are disclosed in detail, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and the embodiments of the present invention include many changes, modifications and equivalents. Attached Figure Description

[0018] Figure 1 A schematic diagram of a coalbed methane collection device; Figure 2 In this utility model Figure 1 Enlarged structural diagram at point A; Figure 3 This is a schematic diagram of the gas collecting pipe in this utility model; Figure 4 This is a schematic diagram of the pressure drop and flow capacity test of the gas collecting pipe in this utility model.

[0019] In the diagram: 1. Tank support base; 2. Gas gathering and transportation tank; 3. Gas gathering pipe; 31. First tapered section; 32. First throat flow stabilizing section; 33. First tapered and pressurized section; 34. Second tapered section; 35. Second throat flow stabilizing section; 36. Second tapered and pressurized section; 37. Third tapered section; 38. Third throat flow stabilizing section; 39. Third tapered and pressurized section. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit its scope.

[0021] It should be noted that when an element is referred to as "set on" or "provided with" another element, it can be directly on the other element or there may be an intermediate element. When an element is referred to as "connected to" or "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. "Fixed connection" means fixed connection. There are many ways of fixed connection, which are not within the scope of protection of this document. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this document are only for illustrative purposes and do not represent the only implementation method.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terms used in the description herein are for the purpose of describing particular embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Please refer to the instruction manual appendix. Figure 1-4 To address the problems of significant pressure drop abruptly, high system flow resistance, and severe solid particle abrasion caused by the use of straight pipes or single contraction pipe structures in existing coalbed methane collection pipelines, this utility model provides a specific embodiment of a coalbed methane collection device. In this embodiment, the existing coalbed methane collection device includes the following parts: Tank support base 1 is installed on the ground; Gas gathering and transport tank 2 is installed on the tank support base 1; A gas collection pipe 3 is connected below the gas collection and transportation tank 2 and extends partially underground; Multiple Venturi-like tube units are connected in series along the gas flow direction of gas collecting pipe 3.

[0023] In this embodiment, each Venturi tube unit includes, from top to bottom, the following: Converging section: used to guide and accelerate gas; Throat stabilizing pipe section: connected downstream of the tapering pipe section, forming the minimum cross-section of the airflow channel; Gradually increasing pressure pipe section: connected downstream of the throat stabilizing pipe section, with a gradually increasing cross-section.

[0024] Specifically, the structure of the gas collecting pipe 3 is as follows: A first tapered pipe section 31 is installed at two locations adjacent to the gas gathering and transportation tanks; The first tapering pipe section 31 is connected downstream to the first throat flow stabilizing pipe section 32; The first throat flow stabilizing pipe section 32 is connected downstream to the first gradually increasing pressure pipe section 33; The downstream of the first tapered expansion pipe section 33 is connected to the second tapered contraction pipe section 34; The downstream of the second tapering pipe section 34 is connected to the second throat flow stabilizing pipe section 35; The second throat stabilizing pipe section 35 is connected downstream to the second gradually increasing pressure pipe section 36.

[0025] Specifically, the further optimization of the above technical solution is as follows: The diameter of the inlet end of the first tapered tube section 31 is different from the diameter of the outlet end of the first tapered expansion tube section 33.

[0026] The inlet diameter of the second tapered section 34 is different from the outlet diameter of the second tapered expansion section 36.

[0027] Preferably, the diameter of the inlet end of the first tapered tube section 31 is larger than the diameter of the outlet end of the first tapered expansion tube section 33.

[0028] The downstream of the second gradually increasing pressure pipe section 36 can be further connected to the third gradually decreasing pipe section 37; the downstream of the third gradually decreasing pipe section 37 is connected to the third throat stabilizing pipe section 38; the downstream of the third throat stabilizing pipe section 38 is connected to the third gradually increasing pressure pipe section 39 (i.e., extended into a three-stage series).

[0029] The outlet diameter of the first gradually increasing pressure tube section 33 is the same as the inlet diameter of the second gradually decreasing pressure tube section 34; the outlet diameter of the second gradually increasing pressure tube section 36 is the same as the inlet diameter of the third gradually decreasing pressure tube section 37 (to ensure a smooth transition of the flow path).

[0030] The gas collecting pipe 3 adopts a modular and detachable structure. Preferably, the gas collecting pipe 3 is designed as a threaded connection, snap-fit ​​connection, or other detachable connection structures.

[0031] In summary, this embodiment employs a multi-stage tandem Venturi-like structure to replace straight pipes or single-stage contraction pipes. Gas flow through multiple throat-stabilizing pipe sections achieves phased acceleration, distributing the overall pressure drop across each unit and avoiding sudden local pressure drops. Each gradually increasing pressure pipe section, through cross-sectional expansion, promotes the conversion of gas kinetic energy into static pressure energy based on fluid dynamics principles, achieving pressure recovery. This significantly reduces the gas flow resistance of the pipeline system and improves the stability of high-solids coalbed methane transportation.

[0032] Furthermore, considering that the two most important parameters for coalbed methane transportation are the maximum pressure drop and the maximum inlet flow rate of the pipeline, this utility model adopts the following approach. Figure 4 The pressure drop and flow capacity test of the gas collecting pipe is shown in the following specific test plan: Test subjects: A total of 5 groups of gas collecting tubes were tested. Control group: 4 groups using gas collection tubes with a single-stage contraction structure 3.

[0033] Experimental group: Group 1 uses the gas collecting pipe 3 with the multi-stage series Venturi tube structure of this utility model.

[0034] Controlled variables: The diameters of the inlet and outlet of all test gas collection tubes 3 were kept consistent to ensure a fair comparison.

[0035] Five sets of gas collecting pipes 3 were connected to the test bench of this application.

[0036] Test items: Conduct pressure drop test and flow capacity test.

[0037] Experimental results: The pressure drops of the control group (single-stage contraction structure) were 152 Pa, 136 Pa, 139 Pa, and 144 Pa (mean ≈ 142.75 Pa).

[0038] The pressure drop value of the experimental group (the structure of this utility model) is 87 Pa.

[0039] Conclusion: The pressure drop of this utility model structure is significantly reduced by about 39% compared with the existing single-stage contraction structure, which verifies the effect of this application in dispersing pressure drop and reducing total flow resistance.

[0040] Maximum traffic test results: The maximum flow rates of the control group (single-stage contraction structure) were 896 kg / h, 890 kg / h, 877 kg / h, and 869 kg / h (mean ≈ 883 kg / h).

[0041] The maximum flow rate of the experimental group (the structure of this utility model) is 833 kg / h.

[0042] Conclusion: Under the same inlet and outlet diameter conditions, the maximum flow rate of this utility model structure is slightly lower than that of the control group, by about 5.7%. This result is in line with expectations, stemming from the rectifying effect of the multi-stage structure on the flow and the improved efficiency of kinetic energy to pressure energy conversion. Although some limiting flow velocity is sacrificed, the system pressure stability and energy consumption are significantly optimized, making it more practically significant for the transportation of solid coalbed methane. Therefore, compared with the existing simple contraction-type pipeline structure, the pipeline structure of this application is more conducive to coalbed methane collection and utilization.

[0043] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A coal bed gas collection apparatus, characterized by, The system includes a tank support base (1) placed on the ground, a gas gathering tank (2) installed on the tank support base (1), a gas gathering pipe (3) partially extending into the ground connected below the gas gathering tank (2), a first tapering pipe section (31) provided near the gas gathering tank (2) on the gas gathering pipe (3), a first throat stabilizing pipe section (32) connected below the first tapering pipe section (31), a first tapering amplifying pipe section (33) connected below the first throat stabilizing pipe section (32), a second tapering pipe section (34) connected to the first tapering amplifying pipe section (33), a second throat stabilizing pipe section (35) connected below the second tapering pipe section (34), and a second tapering amplifying pipe section (36) connected to the second throat stabilizing pipe section (35).

2. A coal bed gas collection apparatus according to claim 1, wherein: The inlet portion of the first tapered tube section (31) has a different diameter than the outlet portion of the first tapered amplifying tube section (33).

3. A coal bed gas collection apparatus according to claim 2, wherein: The inlet portion of the second tapering section (34) has a different diameter than the outlet portion of the second tapering expanding section (36).

4. A coal bed gas collection apparatus according to claim 3, wherein: The diameter of the inlet portion of the first tapered section (31) is larger than that of the outlet portion of the first tapered booster section (33).

5. A coal bed gas collection apparatus according to claim 4, wherein: The second gradually increasing pressure tube section (36) is connected to a third gradually decreasing tube section (37) below it, the third gradually decreasing tube section (37) is connected to a third throat stabilizing tube section (38) below it, and the third gradually increasing pressure tube section (39) is connected to the third throat stabilizing tube section (38) below it.

6. A coal bed gas collection apparatus according to claim 5, wherein: The first gradually increasing pressure tube section (33) has the same diameter as the second gradually decreasing pressure tube section (34), and the second gradually increasing pressure tube section (36) has the same diameter as the third gradually decreasing pressure tube section (37).

7. A coal bed gas collection apparatus according to claim 6, wherein: The gas collecting pipe (3) adopts a modular and detachable structure.

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