Rotary blowout preventer for coal mine drilling machine

Abstract

The invention belongs to the field of mechanical design, and relates to a rotary blowout preventer for a coal mine drilling machine. The core structure comprises a transition four-way joint which is provided with a deflation valve and a water drain valve which are respectively used for discharging gas and drilling slag and water; the rotary sealing device comprises a shell, a front end cover, a rear end cover, a rotary inner sleeve and a sealing rubber sleeve, the sealing rubber sleeve is in an inverted cone shape, self-sealing is achieved through the pressure of media returning out of a hole, and the holding force on the drill rod is enhanced. In addition, the device is further provided with an axial limiting structure, various sealing pieces, a nylon supporting ring, a lubricating nipple and other auxiliary components. In some embodiments, an auxiliary sealing ring is additionally arranged on the inner side of the large end of the sealing rubber sleeve, and double-sealing guarantee is formed. The device can effectively solve the problems that an existing coal mine drilling gas leakage-proof device is rapid in sealing abrasion, poor in high-pressure sealing performance and the like, and safe production of a coal mine is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of mechanical design, and relates to a rotary blowout prevention device for a coal mine drilling machine. BACKGROUND

[0002] In coal mining operations, as the mining depth continues to increase, the geological conditions of the coal seam become increasingly complex, and the gas permeability coefficient decreases significantly, leading to an increase in coal seam gas pressure and ground stress. This change poses a serious challenge to coal mine safety production, especially the increasing threat of dynamic disasters such as coal and gas outburst. In order to effectively eliminate the outburst danger of the coal seam, improve the gas permeability of the coal seam, and expand the gas extraction radius, thereby improving the gas extraction effect, coal mining enterprises widely adopt a series of advanced technologies, among which the integrated operation of hydraulic flushing becomes one of the key means.

[0003] The integrated operation of hydraulic flushing is a highly integrated and efficient construction method, which covers five core links of "drilling, prevention, flushing, screening, and measurement". Specifically, the "drilling" link uses a crawler-type drilling machine to drill a coal seam to provide a channel for subsequent operations; the "prevention" link cooperates with the exhaust fan through the blowout prevention module to effectively reduce the outburst of gas during drilling and ensure operation safety; the "flushing" link uses a high-pressure hydraulic flushing pump to impact and break the coal seam, increasing the gas permeability of the coal seam; the "screening" link effectively separates the coal residue and water generated by flushing through a coal-water separation module; and the "measurement" link measures the separated coal residue and sends it to a scraper conveyor for subsequent processing.

[0004] In the above operation process, the blowout prevention module is a key component that ensures operation safety, and its performance directly affects the control effect of gas and drilling residue during drilling construction. The traditional coal mine drilling gas leakage prevention device adopts a sealed box body structure. This structure is connected to the orifice cover or the core tube deep into the orifice through sealing of one end of the sealed box to the coal wall, and the other end is provided with an orifice for the drill rod to pass through. A negative pressure air outlet is provided above the sealed box, and a residue discharge port is connected below the sealed box to achieve the separation and discharge of gas and drilling residue.

[0005] However, the existing sealed box body type leakage prevention device has exposed many problems in actual application. First, the sealing between the sealed box orifice and the drill rod is usually achieved by a rubber ring, but the continuous rotation of the drill rod during operation causes the rubber ring to wear out easily. Once the rubber ring is worn out, the residue water and gas will leak from the gap, and when the leakage reaches a certain threshold, the gas alarm device will be triggered, causing the roadway to be powered off and the construction to be forced to stop, which not only seriously affects the operation safety, but also greatly reduces the construction efficiency. Second, the existing leakage prevention device generally does not have a pressure sealing function, and when the residue water and gas returned from the hole have a certain pressure, the device cannot effectively prevent leakage, further increasing the risk of operation.

[0006] In view of the deficiencies of the prior art, the coal mining industry urgently needs a new blowout preventer that can adapt to a high-pressure environment and effectively prevent gas and drilling residue from leaking. SUMMARY

[0007] Therefore, the present application aims to provide a rotary blowout preventer for a coal mine drilling rig to solve the existing problems.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solution: a rotary blowout preventer for a coal mine drilling rig, which is sleeved on a drill pipe and connected to a core tube, comprising a transition cross that is connected to the core tube, and a rotary sealing device that is connected to the transition cross; the rotary sealing device comprises an outer shell, a front end cover and a rear end cover that are fixedly connected to the outer shell by fasteners, a rotary inner sleeve that is rotatably installed inside the outer shell by a bearing, and a sealing rubber sleeve that is arranged between the rotary inner sleeve and the drill pipe, one end of the front end cover is connected to the outer shell, and the other end is connected to the transition cross; the sealing rubber sleeve is sleeved on the drill pipe, has an inverted conical shape, and gradually decreases in diameter in the axial direction of the drill pipe towards the transition cross, and the smallest inner diameter end of the sealing rubber sleeve has a size that is smaller than the outer diameter of the drill pipe in a natural state, thereby forming an initial grip on the drill pipe; a gap is provided between the sealing rubber sleeve and the rotary inner sleeve, and the gap is in communication with an external orifice through the transition cross, when the medium in the orifice acts on the gap, the sealing rubber sleeve is driven to contract radially to enhance the gripping force and achieve self-sealing.

[0009] Optionally, one end of the sealing rubber sleeve with a large diameter is fixed to one end of the rotary inner sleeve away from the transition cross by a pressure ring, and the pressure ring is fixedly connected to the rotary inner sleeve by bolts.

[0010] Optionally, the transition cross is provided with a gas vent valve and a water vent valve, the gas vent valve is connected to a gas extraction pipeline, and the water vent valve is connected to a mixed discharge pipeline of drilling residue and water.

[0011] Optionally, the middle part of the rotary inner sleeve is provided with an axial limiting structure, the axial limiting structure comprises a retaining ring and a half ring arranged on the outer circumference of the rotary inner sleeve, and the retaining ring and the half ring are clamped in the inner ring of the bearing.

[0012] Optionally, the front end cover and the rear end cover are connected to the outer shell by bolts respectively, and O-shaped sealing rings are arranged between the front end cover, the rear end cover and the outer shell respectively as sealing members of the front end cover, the rear end cover and the outer shell.

[0013] Optionally, a skeleton sealing ring is further arranged between the rotary inner sleeve and the front end cover and the rear end cover as a sealing member of the rotary inner sleeve and the front end cover and the rear end cover.

[0014] Optionally, a dustproof sealing ring is further arranged between the bearing and the front end cover to prevent the medium in the orifice from entering the lubrication and sealing cavity of the bearing.

[0015] Optionally, the inner side of the front end cover is provided with a nylon support ring, the inner diameter of which matches the gap between the drill rod, so as to prevent the drill rod from being excessively flexible and protect the sealing rubber sleeve.

[0016] Optionally, the shell is further provided with a refueling nozzle, which is communicated with the cavity where the bearing is located through an oil channel.

[0017] Optionally, the inner side of the end with a larger diameter of the sealing rubber sleeve is further provided with an auxiliary sealing ring, which is inverted conical, the diameter of which gradually decreases along the axial direction of the drill rod towards the transition cross.

[0018] Optionally, the inclination angle between the auxiliary sealing ring and the drill rod is larger than the inclination angle between the front end of the sealing rubber sleeve and the drill rod.

[0019] Optionally, a gap is arranged between the transition cross and the drill rod and is communicated with the core tube; the gap between the inner wall of the transition cross and the drill rod, the gap between the inner wall of the nylon support ring and the drill rod, and the gap between the sealing rubber sleeve and the rotating inner sleeve are sequentially communicated, forming a continuous pressure transmission cavity.

[0020] The beneficial effects of the present application are as follows:

[0021] 1. effectively reducing the risk of sealing wear; the synchronous rotation design of the rotating inner sleeve and the drill rod makes the sealing rubber sleeve rotate synchronously with the drill rod, avoiding the rapid wear problem of the traditional rubber ring caused by one-way friction. This dynamic sealing mechanism significantly prolongs the service life of the sealing element and reduces the gas leakage risk caused by sealing failure, providing more reliable sealing protection for drilling operations.

[0022] 2. realizing self-sealing under high pressure conditions; the pressure of the medium returned from the hole is used to drive the sealing rubber sleeve to contract radially, forming a pressure self-adaptive sealing structure. When the gas or water pressure exceeds 1Mpa, the gripping force between the sealing rubber sleeve and the drill rod is automatically enhanced, and no additional power is needed to maintain the sealing efficiency. This passive sealing design is particularly suitable for high-pressure environments in deep coal seams, effectively solving the leakage problem of traditional devices under high-pressure conditions.

[0023] 3. building a safe and environmentally friendly transportation system; through the shunt design of the transition cross, the gas is introduced into the negative pressure extraction pipeline through the gas valve, and the drill slag and water are discharged into the special treatment system through the water valve. This closed-loop transportation method avoids the diffusion of harmful substances to the roadway, not only protecting the health of the operating personnel, but also meeting the requirements of green mining in coal mines, significantly improving the working environment in the mine.

[0024] 4、Strengthen the stability and protection performance of the structure; The nylon support ring provided on the front end cover forms a flexible cooperation with the drill pipe, which limits the radial jumping of the drill pipe while allowing the axial movement of the drill pipe, preventing the eccentric rotation of the drill pipe from causing the eccentric wear of the sealing rubber sleeve. The dustproof sealing ring effectively prevents the drill cuttings and water returned from the hole from entering the bearing cavity, avoiding the bearing from being stuck or failing due to pollution, and ensuring the long-term stable operation of the rotating part.

[0025] 5、Optimize the maintenance process and use cost; The modular design enables the key components such as the compression ring and the skeleton sealing ring to be quickly disassembled and replaced, significantly improving the maintenance efficiency. The bearing cavity pressure lubrication system realized through the oil filler nozzle can effectively prevent the invasion of external pollutants and reduce the consumption of lubricants. Compared with the traditional sealing box body which needs to be frequently stopped for maintenance and replacement of rubber rings, the comprehensive maintenance cost of the device is lower, and the service life is longer.

[0026] 6、Improve the safety and continuity of operation; The linkage design of the self-sealing mechanism and the pressure monitoring enables the device to maintain sealing efficiency when the gas pressure is abnormal, avoiding emergency shutdown caused by gas leakage.

[0027] Other advantages, objects and features of the present application will be in part apparent and in part pointed out hereinafter in the specification, and will be the subject of the claims appended hereto. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the specification as follows. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the preferred detailed description of the present application will be given below in combination with the drawings, in which:

[0029] Fig. 1 is the overall structure of the present application;

[0030] Fig. 2 is the working principle diagram of the present application; (the arrows in the figure show the movement direction of the water and gas returned from the hole, and the direction of the force generated on the rubber sleeve when the water and gas are blocked after being transported to the rubber sleeve).

[0031] Reference signs: 1-Compression ring; 2-Sealing rubber sleeve; 3-Rotary inner sleeve; 4-Retainer ring; 5-Half ring; 6-Rear end cover; 7-O-ring seal; 8-Bearing; 9-Skeleton seal ring; 10-Dustproof sealing ring; 11-Shell; 12-Front end cover; 13-Nylon support ring; 14-Deflation valve; 15-Transition cross; 16-Water drain valve, 17-Drill pipe, 18-Oil filler nozzle. DETAILED DESCRIPTION

[0032] The following specific examples 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. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] Example 1,

[0036] Please see Figs. 1-2 This is a rotary blowout preventer for coal mine drilling rigs, sleeved on the outside of drill rod 17 and connected to the core tube. Its specific structure is as follows:

[0037] Transition tee 15: Serves as a connection hub between the device and external pipelines, and is equipped with a vent valve 14 and a drain valve 16. The vent valve 14 is connected to the gas extraction pipeline and is used to discharge the gas that emerges during drilling; the drain valve 16 is connected to the mixed discharge pipeline of drill cuttings and water and is used to discharge the coal slag and water generated during drilling.

[0038] Rotary sealing device: includes a housing 11, a front cover 12 and a rear cover 6 fixedly connected to the housing by bolts, a rotating inner sleeve 3 rotatably installed inside the housing 11 by bearing 8, and a sealing sleeve 2 disposed between the rotating inner sleeve 3 and the drill rod 17.

[0039] Sealing sleeve 2: Sleeves onto drill rod 17, shaped like an inverted cone, with its diameter gradually decreasing along the axial direction of drill rod 17 towards transition tee 15. The smallest inner diameter of sealing sleeve 2 in its natural state is smaller than the outer diameter of drill rod 17, creating an initial grip on drill rod 17. A gap is provided between sealing sleeve 2 and rotating inner sleeve 3, which communicates with the external orifice through transition tee 15. When the pressure of the returning medium inside the orifice acts on this gap, it drives sealing sleeve 2 to contract radially to enhance the gripping force and achieve self-sealing.

[0040] Pressure ring 1: The larger diameter end of the sealing sleeve 2 is fixed to the end of the rotating inner sleeve 3 away from the transition four-way 15 by a pressure ring. The pressure ring 1 and the rotating inner sleeve 3 are fixedly connected by bolts.

[0041] Axial limiting structure: The middle part of the rotating inner sleeve 3 is provided with an axial limiting structure, including a retaining ring 4 and a half ring 5 set on the outer circumference of the rotating inner sleeve 3. The retaining ring 4 and the half ring 5 are engaged with the inner ring of the bearing 8 to prevent the rotating inner sleeve 3 from moving axially.

[0042] Sealing element: The front cover 12 and the rear cover 6 are respectively connected to the outer shell 11 by bolts, and O-rings 7 are provided between the front cover 12, the rear cover 6 and the outer shell 11, respectively, as sealing elements between the front cover 12, the rear cover 6 and the outer shell 11.

[0043] A skeleton sealing ring 9 is also provided between the rotating inner sleeve 3 and the front and rear end covers, serving as a sealing element between the rotating inner sleeve 3 and the front end cover 12 and the rear end cover 6.

[0044] A dustproof sealing ring 10 is also provided between the bearing 8 and the front cover 12 to prevent the medium returning from the hole from entering the bearing lubrication sealing cavity.

[0045] Nylon support ring 13: A nylon support ring 13 is provided on the inner side of the front end cover 12. Its inner diameter is matched with the drill rod clearance to prevent the drill rod 17 from deflecting too much and to protect the sealing sleeve 2.

[0046] Oil filler nozzle 18: The outer shell 11 is also equipped with an oil filler nozzle, whose oil passage is connected to the bearing cavity. It is used to add grease to the bearing cavity to lubricate the bearing 8, and at the same time, to maintain a certain pressure in the bearing cavity to prevent sludge and water from entering the bearing cavity and contaminating the bearing.

[0047] Working Principle: The front end of this device connects to the core tube extending into the borehole. During drilling, drill cuttings, water, and gas will return from the borehole. The sealing sleeve 2 tightly grips the drill rod 17, effectively preventing drill cuttings, water, and gas from overflowing from the drill rod end. The sealing sleeve 2 and the rotating inner sleeve 3 rotate together with the drill rod 17. If the water and gas returning from the borehole have a certain pressure, this pressure will act laterally on the sealing sleeve, making the sealing sleeve 2 grip the drill rod with greater force, achieving self-sealing of gas or liquid pressure exceeding 1 MPa (the higher the pressure of the cuttings, water, and gas, the greater the pressure on the conical surface, and the better the seal between the sleeve and the drill rod). The drain valve 16 is connected to the cuttings discharge pipe, through which drill cuttings and water are discharged; the vent valve 14 is connected to the negative pressure pipe, through which gas is discharged.

[0048] Example 2,

[0049] Based on Example 1, this embodiment adds an auxiliary sealing ring to the inner side of the end with the larger diameter of the sealing sleeve. The specific structure is as follows:

[0050] Auxiliary sealing ring: The auxiliary sealing ring is inverted conical in shape, with its diameter gradually decreasing along the drill pipe axis towards the transition four-way valve. Furthermore, the smallest inner diameter end of the auxiliary sealing ring is smaller than the outer diameter of the drill pipe in its natural state. The inclination angle between the auxiliary sealing ring and the drill pipe is greater than the inclination angle between the front end of the sealing sleeve (the end in contact with the drill pipe) and the drill pipe, to enhance the auxiliary sealing effect.

[0051] Working Principle: Based on the working principle of Example 1, the added auxiliary sealing ring further enhances the sealing effect of the device on the drill rod. When water and gas returning from the borehole are under pressure, not only will the sealing sleeve be subjected to pressure, increasing its grip on the drill rod, but the auxiliary sealing ring will also be pressed tightly against the drill rod, forming a double seal. This design is particularly suitable for high-pressure conditions and can more effectively prevent gas and water leakage.

[0052] Meanwhile, compared to single-stage seals, multi-stage sealing sleeves can still provide a seal to the drill pipe even when there are deposits or unevenness on the drill pipe interface or drill pipe.

[0053] Example 3,

[0054] Based on Example 2, this embodiment uses rubber for the sealing sleeve, and the rubber has different hardness at different sealing levels.

[0055] In this embodiment, in order to allow the rubber sleeve to have a larger deformation range, the hardness of the first-level rubber at the front end of the seal (the end closest to the transition four-way valve) is selected as 30-50HA, and the hardness of the other rubber levels at the rear end is selected as 50-70HA.

[0056] Through the descriptions of Embodiments 1, 2, and 3 above, it can be seen that the rotary blowout preventer for coal mine drilling rigs of the present invention effectively solves the problems of rapid seal wear and poor high-pressure sealing performance of existing coal mine borehole gas leak prevention devices through structural innovations such as the synchronous rotation design of the rotating inner sleeve and the drill rod, the self-sealing mechanism, and the addition of an auxiliary sealing ring, thus providing a strong guarantee for safe coal mine production.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A rotary blowout preventer for a coal mine drilling rig, sleeved on the outside of the drill rod and connected to the core tube, characterized in that: Includes a transition tee connected to the core tube, and a rotary sealing device connected to the transition tee; The rotary sealing device includes a housing, a front cover and a rear cover fixedly connected to the housing by fasteners, a rotary inner sleeve rotatably installed inside the housing by bearings, and a sealing rubber sleeve disposed between the rotary inner sleeve and the drill rod. One end of the front cover is connected to the housing, and the other end is connected to the transition four-way connector. The sealing sleeve is fitted onto the drill rod and is in the shape of an inverted cone. Its diameter gradually decreases along the drill rod axis towards the transition four-way, and the smallest inner diameter end of the sealing sleeve is smaller than the outer diameter of the drill rod in its natural state, thus forming an initial grip on the drill rod. There is a gap between the sealing sleeve and the rotating inner sleeve, and the gap between the sealing sleeve and the rotating inner sleeve is connected to the external orifice through the transition four-way. When the pressure of the medium returning from the hole acts on the gap between the sealing sleeve and the rotating inner sleeve, it drives the sealing sleeve to contract radially to enhance the gripping force.

2. The rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: The larger diameter end of the sealing sleeve is fixed to the end of the rotating inner sleeve away from the transition four-way valve by a pressure ring, and the pressure ring and the rotating inner sleeve are fixedly connected by bolts.

3. The rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: The transition four-way valve is equipped with an air release valve and a water release valve. The air release valve is used to connect to the external gas extraction pipeline, and the water release valve is used to connect to the external pipeline for the mixed discharge of drilling cuttings and water.

4. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: The rotating inner sleeve is provided with an axial limiting structure in the middle. The axial limiting structure includes a retaining ring and a semi-ring on the outer circumference of the rotating inner sleeve. The retaining ring and the semi-ring are engaged with the inner ring of the bearing.

5. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: The front cover and the rear cover are respectively connected to the outer shell by bolts, and O-rings are provided between the front cover and the rear cover and the outer shell as sealing elements.

6. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: A skeleton sealing ring is also provided between the rotating inner sleeve and the front and rear end covers, serving as a sealing element between the rotating inner sleeve and the front and rear end covers.

7. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: A dustproof sealing ring is also provided between the bearing and the front cover to prevent the medium returning from the hole from entering the bearing lubrication and sealing cavity.

8. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: The inner side of the front cover is provided with a nylon support ring. The inner diameter of the nylon support ring is matched with the drill rod clearance to prevent excessive drill rod deflection and protect the sealing sleeve.

9. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: The outer casing is also equipped with a filler nozzle, which is connected to the bearing cavity via an oil passage.

10. A rotary blowout preventer for coal mine drilling rigs according to claim 1, characterized in that: An auxiliary sealing ring is also provided on the inner side of the end with the larger diameter of the sealing sleeve. The auxiliary sealing ring is inverted conical in shape, and its diameter gradually decreases along the drill rod axis toward the transition four-way. Furthermore, the smallest inner diameter end of the auxiliary sealing ring is smaller than the outer diameter of the drill rod in its natural state.

11. A rotary blowout preventer for coal mine drilling rigs according to claim 10, characterized in that: The inclination angle between the auxiliary sealing ring and the drill pipe is greater than the inclination angle between the front end of the sealing sleeve and the drill pipe.

12. A rotary blowout preventer for coal mine drilling rigs according to claim 10, characterized in that: The auxiliary sealing ring and the sealing sleeve are integrally molded.

13. A rotary blowout preventer for coal mine drilling rigs according to claim 8, characterized in that: The transition four-way valve is provided with a gap between itself and the drill pipe, and is connected to the core tube. The gaps between the inner wall of the transition four-way valve and the drill pipe, the gaps between the inner wall of the nylon support ring and the drill pipe, and the gaps between the sealing sleeve and the rotating inner sleeve are sequentially connected to form a continuous pressure transmission cavity.

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