A gasifying agent injection tool for underground coal gasification

Abstract

This utility model relates to the fields of oil and gas industry and clean coal technology, and discloses a gasifying agent injection tool for underground coal gasification. This device is used in underground coal gasification where oxygen / air and water are injected as gasifying agents into the coal seam in the combustion zone through a continuous tubing, injection tool body, check valve, extension pipe, and guide nozzle for gasification and combustion reaction. It mainly includes a continuous tubing connector, injection tool body, check valve, front nozzle, extension pipe, and guide nozzle. This utility model's gasifying agent injection tool can achieve safe unlocking, separation, and overload protection through controllable shearing, ensuring that other upstream equipment can be quickly pulled back, maintained, and replaced in a timely manner, thereby reducing equipment wear in the underground coal gasification process to a certain extent.

Description

Technical Field

[0001] This utility model relates to the fields of oil and gas industry and clean coal technology, and more specifically, it relates to a gasifying agent injection tool for underground coal gasification. Background Technology

[0002] Underground coal gasification (ISC) is a process that directly converts coal into gaseous products through controlled combustion (incomplete combustion) and gasification reactions in underground coal seams. The product gas, often referred to as syngas, can be used as a feedstock for downstream processes such as fuel production, chemical production, and power generation. Utility Model Content

[0003] This invention provides a gasifying agent injection tool for underground coal gasification, solving the technical problem of equipment wear in underground coal gasification processes.

[0004] This utility model provides a gasifying agent injection tool for underground coal gasification. The gasifying agent injection tool includes a continuous oil pipe connector that is airtightly connected to each other in sequence, an injection tool body, a check valve, a front nozzle, an extension pipe, and a guide nozzle.

[0005] The coiled tubing connector is a structure that connects the coiled tubing to the vaporizing agent injection tool, and is connected by welding or riveting. The injection tool body has a coiled tubing component at the rear end and a check valve assembly at the front end. The release assembly on the outer sleeve is connected to the injection tool body. The check valve is connected to the outer sleeve and also to the front nozzle. The front nozzle is connected to an extension tube, which injects the vaporizing agent into the combustion air zone after passing through the extension tube and the guide nozzle. The extension tube is connected to the part of the vaporizing agent injection tool closest to the combustion air zone. The guide nozzle is connected to the end of the last extension tube closest to the vaporization zone.

[0006] Furthermore, the front nozzle is used to inject air / oxygen and water into the combustion and vaporization zone, and is also combined with a spiral flow to achieve a rotating flow of two phases.

[0007] Furthermore, the release component is used to enable the injection tool body to be safely unlocked, separated, and overload protected through controllable shearing.

[0008] Furthermore, the check valve is a lift check valve, a flange check valve, or an axial check valve, used to keep the tools and continuous tubing clean when there is no flow, while preventing reverse flammable and explosive gas contamination and damage to upstream equipment.

[0009] Furthermore, the gasifying agent injection tool also includes a centralizer, which mainly uses a mechanical structure to keep the main body of the injection tool centered and aligned in the underground gasifier, reducing eccentricity and ensuring the effectiveness of the injection tool body.

[0010] Furthermore, the vaporizing agent injection tool also includes an O-ring, which is used to achieve a sealing effect between the inner component and the outer sleeve.

[0011] Furthermore, the vaporizing agent injection tool has an outer sleeve.

[0012] Furthermore, the continuous tubing is made of 316L stainless steel, 2205 duplex stainless steel, 254SMO super austenitic stainless steel, or 2507 super duplex stainless steel.

[0013] Furthermore, the body of the injection tool is made of 316L stainless steel, Inconel 625 stainless steel, or 2205 duplex stainless steel.

[0014] Furthermore, the wall thickness of the injection tool body and the extension tube shell is 10-20 mm to meet the heat dissipation and cooling requirements of reverse thermal radiation, thermal convection and thermal conduction generated in the high-temperature zone.

[0015] The beneficial effects of this utility model are as follows: the gasifying agent injection tool of this utility model can achieve safe unlocking, separation and overload protection of the gasifying agent injection tool through controllable shearing, which can ensure that other upstream equipment can be quickly pulled back, maintained and replaced in a timely manner, thereby reducing equipment wear in the underground coal gasification process to a certain extent. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the gasifying agent injection tool for underground coal gasification according to this utility model.

[0017] In the diagram: 1. Coiled tubing; 2. Coiled tubing connector; 3. Release assembly; 4. O-ring; 5. Centralizer; 6. Injection tool body; 7. Outer sleeve; 8. Check valve; 9. Front nozzle; 10. Extension tube; 11. Guide nozzle. Detailed Implementation

[0018] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0019] At least one embodiment of this utility model discloses a gasifying agent injection tool for underground coal gasification, such as... Figure 1As shown, the airtight components of the vaporizing agent injection tool connected in sequence include a continuous tubing connector 2, the injection tool body 6, a check valve 8, a front nozzle 9, an extension tube 10, and a guide nozzle 11.

[0020] The coiled tubing connector 2 is a structure that connects the coiled tubing 1 to the injection tool. It can be connected by welding, riveting, or other methods. Oxygen, air, or water from the ground device is transported to the injection tool body 6 through the coiled tubing 1. Then, it is injected into the combustion zone through the injection tool body 6, check valve 8, extension pipe 10, and guide nozzle 11 to undergo gasification and combustion reaction with the coal seam.

[0021] The outer / inner diameter of coiled tubing 1 is determined based on the required oxygen and water flow rate and the reasonable pressure drop along coiled tubing 1. The material selection is 316L stainless steel, 2205 duplex stainless steel, or even better, 254SMO super austenitic stainless steel and 2507 super duplex stainless steel.

[0022] Check valve 8, a high-flow, two-phase flow, spring-loaded (low burst pressure, <1 barg) axially movable check valve 8, is used to keep the injection tool body 6 and the continuous tubing 1 clean when there is no flow, while preventing reverse flammable and explosive gas contamination and damage to upstream equipment.

[0023] The check valve 8 provides reverse flow protection when the flow of oxygen and water is interrupted (no flow), thereby preventing syngas from flowing back / intruding and contaminating the interior of the coiled tubing 1. Lift check valve 8, flange check valve 8, and axial (nozzle) check valve 8 can be selected, etc.

[0024] The front nozzle 9, connected to the outlet of the check valve 8, is used to inject oxygen / air and water into the combustion and vaporization zone (if the extension tube 10 is not present). Alternatively, it can be connected to the extension tube 10 to inject the vaporizing agent into the combustion-air zone after passing through the extension tube 10 and the guide nozzle 11. Furthermore, it can be combined with a helical flow to achieve a rotating two-phase flow.

[0025] The release assembly 3 is a precision-machined structure for installing shear pins. It has a preset shear value and applies hydraulic shearing from the ground. It is primarily used in the injection tool body 6 to achieve safe unlocking, separation, and overload protection of the injection tool body 6 through controlled / sacrificial shearing.

[0026] Extension tubes 10 are added as specific components, attached to the front end of the injection tool body 6 (the part closest to the ignition zone), thus keeping critical components such as the check valve 8 and the continuous tubing 1 away from the ignition zone. Multiple extension tubes 10 can be connected.

[0027] The extension tube 10 exhibits an annular flow pattern, which facilitates cooling of its metal walls when exposed to high vaporization temperatures, partially converting water into steam. The diameter and design dimensions of these extension tubes 10 are determined based on the operating pressure range to ensure that the two-phase flow can be maintained from the annular flow mode to the entrained flow mode. Multiple extension tubes 10 can be interconnected to increase the distance between the guide nozzle 11 and the check valve 8.

[0028] A guide nozzle 11 is added at the end of the last extension tube 10 (the end closest to the vaporization zone) to force the two-phase flow to leave the extension tube 10 at an angle of 20-50 degrees (more preferably 30-40 degrees). The guide nozzle 11 guides the fluid to be sprayed at a certain angle into the combustion zone for vaporization and combustion reaction, mainly serving to optimize the fluid flow direction and cool the equipment to prevent it from being burned out by high temperature.

[0029] The injection tool body 6 has a continuous oil pipe 1 at its rear end and a check valve 8 at its front end. The release assembly 3 on the outer sleeve 7 is connected to the body. The injection tool body 6 must be made of materials suitable for high temperature, high pressure, and high strength environments, such as 316L stainless steel or higher grades of stainless steel such as Inconel 625 or 2205 duplex stainless steel.

[0030] The vaporizing agent flow channel of the main body 6 of the injection tool must be clean and free from particulate or hydrocarbon contamination. All internal surfaces of the entire injection tool equipment must undergo special processing to prevent the risk of spontaneous combustion from particulate impact on the metal internal surfaces in an oxidizing environment.

[0031] The outer shell of the injection tool body 6 and the extension tube 10 must have sufficient wall thickness (10-20mm) to meet the heat dissipation and cooling requirements of reverse heat radiation, heat convection and heat conduction generated by the high temperature zone, prevent any possible reverse combustion, and ensure the integrity and reliability of the entire injection tool equipment.

[0032] The gasifying agent injection tool for underground coal gasification also includes a centralizer 5. The centralizer 5 mainly uses a mechanical structure to keep the main body 6 of the injection tool centered and aligned in the underground gasifier, reducing eccentricity and ensuring the effectiveness of the tool. It also includes an O-ring 4, which is used to achieve a sealing effect between the internal components and the outer sleeve 7.

[0033] The gasifying agent injection tool for underground coal gasification also includes an outer sleeve 7, which can protect the inner injection tool body 6. If the injection tool body 6 gets stuck, it can be automatically broken or torn by the release component 3 so that the remaining injection tool body 6 parts can be retracted.

[0034] The execution steps are as follows:

[0035] First, the surface equipment delivers the gasifying agent downhole through coiled tubing 1. This medium then enters the injection tool body 6 via the connector. The injection tool body 6 is kept in a centered position by the centralizer 5 to ensure effective injection.

[0036] The check valve 8 plays a crucial role: it remains open during normal operation to allow the vaporizing agent to pass through; and it automatically closes when injection stops to prevent backfire. This safety mechanism requires special explanation.

[0037] The design of the extension tube 10 is ingenious: by adding multiple extension tubes 10, key components are kept away from the high-temperature combustion air zone. The angle control of the guide nozzle 11 (30-40 degrees is optimal) optimizes the gasification reaction; this technical detail is worth emphasizing.

[0038] Regarding safety mechanisms: the drop-off component 3 can be hydraulically sheared when it encounters a jam, allowing the recovered portion to be injected into the tool body 6; the outer sleeve 7 provides additional protection.

[0039] These design points demonstrate a thorough consideration of the risks associated with downhole operations. Finally, the gasifying agent is precisely delivered to the combustion zone, where controlled combustion converts solid coal into combustible gas.

[0040] Working principle and process:

[0041] Surface Connection and Media Delivery: The surface equipment (oxygen / air supply system, water pump) is connected to the injection tool body 6 via coiled tubing 1. The vaporizing agent (a two-phase flow consisting of oxygen / air and water) is delivered downwards to the downhole injection tool body 6 via coiled tubing 1.

[0042] Downhole Positioning and Protection: After the injection tool body 6 is lowered to the target position of the underground gasifier, the centralizer 5 automatically deploys, using a mechanical structure to keep the injection tool body 6 centered and aligned within the borehole, preventing eccentricity that could lead to reduced efficiency or damage. The outer sleeve 7 encloses the internal components, providing mechanical protection against the complex downhole environment (such as rock cuttings impact and high temperatures).

[0043] Vaporizing agent flow guidance and backflow prevention: The vaporizing agent enters the main body 6 of the injection tool and flows through the internal channel to the check valve 8. The check valve 8 is kept open at low pressure under spring loading (rupture pressure <1 barg), allowing the vaporizing agent to pass through at high speed; when injection stops or the pressure is abnormal, the check valve 8 closes instantly to prevent flammable and explosive gases (such as CO, H2) generated in the combustion air zone from flowing back into the coiled tubing 1, thus protecting the ground equipment.

[0044] End-point injection and angle control: Option A (without extension pipe 10): The gasifying agent is directly injected from the front nozzle 9. The nozzle can be designed as a spiral flow channel to generate rotation in the two-phase flow, enhancing mixing with the coal seam. Option B (with extension pipe 10): The gasifying agent first passes through the extension pipe 10, which can be connected in multiple sections to push key components such as the check valve 8 away from the high-temperature combustion zone, avoiding thermal damage.

[0045] A flow guide nozzle 11 is installed on the end extension pipe 10 to force the gasifying agent to be sprayed at an angle of 20–50° (preferably 30–40°), covering a wider combustion air cross section and improving the uniformity of the gasification reaction.

[0046] Emergency safety mechanism: If the tool gets stuck or requires emergency retrieval: Hydraulic pressure is applied on the surface, and the shear pin of the release assembly 3 breaks at a preset shear value, separating the outer sleeve 7 from the main body. After separation, the coiled tubing 1 can be safely withdrawn along with core components (injection tool body 6, check valve 8, etc.), while the outer sleeve 7 remains downhole to avoid overall jamming and loss.

[0047] O-ring 4 seals the internal channel throughout, preventing external impurities from entering or gas from leaking.

[0048] The embodiments of the present utility model have been described above. However, the present embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A gasifier injection tool for underground coal gasification, characterized in that, The vaporizing agent injection tool includes a continuous tubing connector, an injection tool body, a check valve, a front nozzle, an extension tube, and a guide nozzle that are connected to each other in a sequential and airtight manner. The coiled tubing connector is a structure that connects the coiled tubing to the vaporizing agent injection tool by welding or riveting. The injection tool body has a coiled tubing component at the rear end and a check valve assembly at the front end. The release assembly on the outer sleeve is connected to the injection tool body. The check valve is connected to the outer sleeve and also to the front nozzle. The front nozzle is connected to an extension tube, which injects the vaporizing agent into the combustion air zone after passing through the extension tube and the guide nozzle. The extension tube is connected to the part of the gasifying agent injection tool closest to the combustion air zone; The guide nozzle is connected to the end of the last extension tube closest to the vaporization zone.

2. A gasifier injection tool for underground coal gasification according to claim 1, wherein, The front nozzle is used to inject air / oxygen and water into the combustion and vaporization zone, and is also combined with a spiral flow to achieve a rotating flow of two phases.

3. A gasifier injection tool for underground coal gasification as claimed in claim 1, wherein, The vaporizing agent injection tool also includes a release assembly, which is used to safely unlock, separate, and overload protect the injection tool body through controllable shearing.

4. A gasifier injection tool for underground coal gasification according to claim 1, wherein, The check valve is a lift check valve, a flange check valve, or an axial check valve, used to keep tools and continuous tubing clean when there is no flow, while preventing reverse flammable and explosive gas contamination and damage to upstream equipment.

5. A gasifier injection tool for underground coal gasification as claimed in claim 1, wherein, The gasifying agent injection tool also includes a centralizer, which mainly uses a mechanical structure to keep the main body of the injection tool centered and aligned in the underground gasifier, reducing eccentricity and ensuring the effectiveness of the injection tool body.

6. A gasifier injection tool for underground coal gasification according to claim 1, wherein, The vaporizing agent injection tool also includes an O-ring, which is used to achieve a seal between the internal components and the outer sleeve.

7. A gasifying agent injection tool for underground coal gasification according to claim 1, characterized in that, The gasifying agent injection tool has an outer sleeve.

8. A gasifying agent injection tool for underground coal gasification according to claim 1, characterized in that, The continuous tubing is made of 316L stainless steel, 2205 duplex stainless steel, 254SMO super austenitic stainless steel or 2507 super duplex stainless steel.

9. A gasifying agent injection tool for underground coal gasification according to claim 1, characterized in that, The body of the injection tool is made of 316L stainless steel, Inconel 625 stainless steel, or 2205 duplex stainless steel.

10. A gasifying agent injection tool for underground coal gasification according to claim 1, characterized in that, The wall thickness of the injection tool body and the extension tube shell is 10-20mm, which is used to meet the heat dissipation and cooling requirements of reverse thermal radiation, thermal convection and thermal conduction generated in the high temperature zone.

Images