Active cooling device for underground coal gasification
Through the carbon dioxide capture, cooling storage and boost injection device, combined with polymer negative carbon filling materials, the cracks and leakage risks caused by rapid cooling during underground gasification of coal are solved, and the effects of slow cooling and zero emissions are achieved.
Patent Information
- Application Number
- CN202422875648.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2034-11-25
AI Technical Summary
During the underground gasification of existing coal, rapid and active cooling leads to sharp changes in the surrounding rock stress field in the combustion air zone, resulting in a large number of cracks, which poses a risk of leakage, and natural cooling leads to large-scale formation deformation and ground subsidence problems.
The carbon dioxide capture, cooling storage and boost injection device are adopted to seal the gasification chamber through slow active cooling, combined with polymer negative carbon filling material, so as to achieve slow cooling and zero emissions in the fuel space.
The stable cooling of the fuel space is achieved, cracks are avoided from drastic temperature changes, the stability of surrounding rocks is ensured, and the goal of zero emissions is achieved, reducing the risk of ground subsidence.
Smart Images
Figure CN223269967U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of underground coal gasification, in particular to an active cooling device for underground coal gasification. Background Art
[0002] Underground coal gasification is a process of controlled combustion of underground coal to produce combustible gas through thermal and chemical reactions on the coal. The coal gasification process generally uses the CRIP (Controlled Retraction and Injection Point) process. Figure 1 As shown, 10 is the gas injection well, 20 is the gas injection horizontal wellbore, 30 is the production well, 40 is the production well cement sheath, and 50 is the coal seam to be gasified. At the beginning of gasification, ignition is carried out at the toe end of the gas injection horizontal wellbore 20 ( Figure 1 (right end in the figure), when the burnout zone reaches the preset range, burn out the toe end string and switch to the gas injection point closer to the heel end of the horizontal well. Similarly, at the end of gasification, if Figure 2 As shown, a long combustion zone 60 is formed inside the coal seam 50 to be gasified, and an annular gap 70 is formed around the production well 30 under the action of high temperature.
[0003] The underground coal gasification process can generally be divided into the gasification heating stage, the stable gasification stage, and the cooling stage. During the stable gasification stage, temperatures reach as high as 1200-1400°C, generating high-temperature thermal stress and drastic changes in the mechanical properties of the surrounding rock, which can severely damage its integrity.
[0004] Passive natural cooling is mostly used during the cooling phase. Under this natural cooling, the high-temperature field generated during the gasification process continues to diffuse to distant strata, causing deformation and damage to a wider range of strata. This significantly impacts the stability of the surrounding rock, especially the deformation of the overlying strata, and can cause severe ground subsidence in shallow coal seams. Field settlement measurements show that subsidence continues even a year after gasification has concluded, indicating that the surface subsidence basin remains unstable during the natural cooling phase.
[0005] Therefore, in the existing technology, in order to accelerate cooling, some adopt rapid active cooling methods, namely water injection methods. However, rapid cooling will cause the stress field of the surrounding rock in the combustion zone to change sharply, resulting in a large number of cracks and causing leakage and pollution risks. Utility Model Content
[0006] The utility model provides an active cooling device for underground coal gasification, which is used to solve the defects in the prior art that rapid active cooling easily leads to a sharp change in the stress field of the surrounding rock in the combustion zone, generates a large number of cracks, and causes leakage risks. It realizes slow active cooling and ensures that the inner wall of the combustion zone will not produce cracks due to drastic temperature changes.
[0007] The utility model also provides an active cooling device for underground coal gasification, comprising:
[0008] A carbon dioxide capture device is used to capture carbon dioxide produced during the gasification process;
[0009] a carbon dioxide cooling and storage device connected to the carbon dioxide capture device, the carbon dioxide cooling device being used to cool and store the captured carbon dioxide;
[0010] A gasification chamber sealing device, used to seal the gasification chamber after gasification is completed;
[0011] The carbon dioxide pressurizing injection device is connected to the carbon dioxide cooling storage device, and the carbon dioxide pressurizing injection device pressurizes and injects the cooled and stored carbon dioxide into the gas injection well.
[0012] According to the utility model, an active cooling device for underground coal gasification is provided, which also includes:
[0013] An intermediate mixing container is connected to the carbon dioxide cooling and storage device upstream and to the carbon dioxide pressurizing and injection device downstream. The intermediate mixing container is used to mix the cooled and stored carbon dioxide and the foaming agent.
[0014] According to an active cooling device for underground coal gasification provided by the present invention, the gasification chamber sealing device includes:
[0015] High molecular weight carbon-negative filler, placed in the annular gap created during the gasification process;
[0016] The casing head is arranged at the top end of the gasification chamber.
[0017] According to the utility model, an active cooling device for underground coal gasification further includes a gas processing device for processing gas in the gasification product.
[0018] According to the utility model, an active cooling device for underground coal gasification further includes a foaming agent supply device connected to the intermediate mixing container, and the foaming agent supply device is used to supply the foaming agent.
[0019] The utility model provides an active cooling device for underground coal gasification. The carbon dioxide generated in the gasification process is captured by a carbon dioxide capture device. The carbon dioxide cooling and storage device cools and stores the captured carbon dioxide. The gasification chamber sealing device seals the gasification chamber. The carbon dioxide pressurized injection device pressurizes and injects the cooled and stored carbon dioxide into the gas injection well. The active cooling method of injecting carbon dioxide gas can not only achieve slow cooling and ensure that the inner wall of the combustion air zone will not produce cracks due to drastic temperature changes; moreover, the carbon dioxide generated in the gasification process is used as a coolant, which can realize the coordinated operation of gasification and carbon sealing and achieve the goal of zero emissions. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0021] Figure 1 It is a structural schematic diagram of the starting state of underground coal gasification in the prior art.
[0022] Figure 2 It is a structural schematic diagram of the final state of underground coal gasification in the prior art.
[0023] Figure 3 This is a structural principle diagram of the active cooling device for underground coal gasification provided by the utility model during the gasification process.
[0024] Figure 4 This is a structural principle diagram of the active cooling device for underground coal gasification provided by the utility model after the gasification process is completed.
[0025] Reference numerals:
[0026] 1. Carbon dioxide capture device; 2. Carbon dioxide cooling and storage device; 21. Carbon dioxide cooling device; 22. Carbon dioxide storage device; 3. Gasification chamber sealing device; 4. Carbon dioxide pressurization injection device; 5. Intermediate mixing container; 31. Polymer negative carbon filler; 32. Casing head; 6. Gasification chamber; 7. Gas treatment device; 8. Foaming agent supply device. DETAILED DESCRIPTION
[0027] To make the purpose, technical solutions, and advantages of the present invention more clear, the following will be combined with the accompanying drawings to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0028] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of 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, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.
[0029] like Figure 3 and Figure 4 As shown, an embodiment of the present invention provides an active cooling device for underground coal gasification, comprising a carbon dioxide capture device 1, a carbon dioxide cooling storage device 2, a gasification chamber sealing device 3 and a carbon dioxide pressurized injection device 4.
[0030] The carbon dioxide capture device 1 is used to capture carbon dioxide generated during the gasification process. The carbon dioxide capture device can use a chemical absorption tower, a membrane separation system, or cryogenic separation technology to efficiently capture carbon dioxide from the mixed gas produced by gasification, thereby reducing carbon dioxide emissions during the underground coal gasification process.
[0031] The carbon dioxide cooling and storage device 2 is connected to the carbon dioxide capture device 1, and the carbon dioxide cooling and storage device 2 is used to cool and store the captured carbon dioxide. The carbon dioxide cooling and storage device 2 may include a carbon dioxide cooling device 21 and a carbon dioxide storage device 22. The carbon dioxide cooling device 21 may use a heat exchanger to cool the captured carbon dioxide gas to a liquid state using cooling water or a low-temperature refrigerant to reduce its volume and facilitate storage. The carbon dioxide storage device 22 may select a pressure-resistant and corrosion-resistant storage tank to ensure long-term safe storage. When carbon dioxide is stored at high pressure, the cooled carbon dioxide gas may be transported to a high-pressure storage tank. A pressure control system is provided inside the storage tank to ensure that the carbon dioxide maintains a stable pressure during storage.
[0032] The carbon dioxide cooling device 21 and the carbon dioxide storage device 22 can effectively reduce the volume and energy loss of carbon dioxide, and improve storage efficiency and safety.
[0033] The gasification chamber sealing device 3 is used to seal the gasification chamber 6 after gasification is completed, creating a closed environment in the gasification chamber 6 to achieve the cooling effect of the injected carbon dioxide gas. It should be noted that during the sealing process, appropriate sealing materials can be selected based on the geological conditions and the shape of the gasification chamber. By precisely controlling the grouting pressure and flow rate, the sealing material can be ensured to evenly fill all annular gaps.
[0034] The carbon dioxide pressurized injection device 4 is connected to the carbon dioxide cooling storage device 2, and the carbon dioxide pressurized injection device 4 injects the cooled stored carbon dioxide into the gas injection well. A high-pressure pump or compressor can be used to pressurize the liquid carbon dioxide to a pressure suitable for injection into the formation.
[0035] The active cooling device for underground coal gasification provided by the embodiment of the present utility model adopts a gas injection cooling method, which can not only achieve slow cooling of the combustion zone and ensure that cracks will not be generated inside the combustion zone due to drastic temperature changes, but also use carbon dioxide in the gasification process as a coolant to achieve coordinated operation of gasification and carbon sealing, thereby achieving the goal of zero emissions.
[0036] In a feasible embodiment of the present invention, it also includes: an intermediate mixing container 5, the upstream of the intermediate mixing container 5 is connected to the carbon dioxide cooling storage device 2, and the downstream of the intermediate mixing container 5 is connected to the carbon dioxide pressurization injection device 4, and the intermediate mixing container 5 is used to mix the cooled and stored carbon dioxide and the foaming agent.
[0037] During CO2 injection, foaming agents help CO2 disperse and dissolve better in the underground medium, thereby improving injection efficiency and storage effectiveness, ensuring that CO2 enters the underground in the optimal form and dispersion. Through the above steps, CO2 and foaming agents are mixed to form CO2 foam, which controls CO2 mobility and reduces gas channeling.
[0038] In a feasible embodiment of the present invention, the gasification chamber sealing device 3 specifically includes a polymer negative carbon filler 31 and a casing head 32. The polymer negative carbon filler 31 is arranged in the annular gap generated during the gasification process; the casing head 32 is arranged at the top of the gasification chamber 6. After the gasification is completed, the polymer negative carbon filler 31 is injected into the production well and the annular gap generated during the gasification process to keep the gasification chamber 6 airtight. More specifically, the polymer negative carbon filler material is first injected into the production well and the annular gap generated during the gasification process; then the airtightness of the gasification chamber is tested, and the test method includes pressure testing, gas leakage testing, etc., to check whether the gasification chamber 6 achieves the expected sealing effect. When the test result meets the pressure requirement, the top of the production well is sealed by the casing head. The casing head 32 is a special sealing device that can ensure the sealing between the production well and the surface.
[0039] It should be noted that the polymer negative carbon filling material is an existing technology and is well known to those skilled in the art, and will not be described in detail here.
[0040] In a feasible embodiment of the present invention, a gas processing device 7 is further included for processing the gas in the gasification product. The gas processing device 7 can be connected to the carbon dioxide capture device 1 to process the gas in the gasification product except carbon dioxide.
[0041] During the underground coal gasification process, the gasification products also contain a variety of other gases, such as carbon monoxide, hydrogen, methane, nitrogen, and small amounts of sulfides and nitrogen oxides. Carbon monoxide and hydrogen can be used to synthesize chemicals such as ammonia and methanol. They can be separated from the gasification products through catalytic conversion, separation and purification, and subsequently utilized. Methane can be processed into standard natural gas through purification and compression for storage and utilization. Nitrogen can be separated from the gasification products through separation and purification, and subsequently utilized. Sulfides and nitrogen oxides can be converted into harmless substances through oxidation, absorption, catalytic conversion, and other technologies, or removed from the exhaust gas through scrubbing, adsorption, and other methods.
[0042] By processing gases other than carbon dioxide in the gasification products while capturing the carbon dioxide generated during the process, it is possible to effectively process and utilize various gases in the gasification products while reducing environmental pollution and energy waste.
[0043] In a feasible embodiment of the present invention, a foaming agent supply device 8 is further included, which is connected to the intermediate mixing container 5. The foaming agent supply device 8 is used to supply the foaming agent. In the intermediate mixing container 5, the carbon dioxide and the foaming agent are mixed. During the carbon dioxide injection process, the foaming agent can help the carbon dioxide to be better dispersed and dissolved in the underground medium, thereby improving the injection efficiency and storage effect, and ensuring that the carbon dioxide can enter the underground in the best form and dispersion during the injection process. Through the above steps, the carbon dioxide and the foaming agent can be mixed to form carbon dioxide foam, so as to control the fluidity of the carbon dioxide and slow down gas channeling.
[0044] Therefore, the active cooling device for underground coal gasification provided by the present invention utilizes slow, active carbon dioxide injection for cooling. This not only prevents cracks in the inner wall of the combustion zone caused by drastic temperature fluctuations, but also utilizes the carbon dioxide produced during the gasification process as a coolant, enabling synergistic gasification and carbon sealing operations, ultimately achieving zero emissions. Furthermore, prior to carbon dioxide injection, negative carbon filling material is applied to the production well, ensuring that damage to the surrounding area during the gasification process does not affect the quality of carbon sealing.
[0045] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.
[0046] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or modes and features of different embodiments or modes described in this specification without contradiction.
[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.
Claims
1. An active cooling device for underground coal gasification, characterized in that: include: A carbon dioxide capture device (1) for capturing carbon dioxide generated during the gasification process; A carbon dioxide cooling and storage device (2) is connected to the carbon dioxide capture device (1), and the carbon dioxide cooling and storage device (2) is used to cool and store the captured carbon dioxide; A gasification chamber sealing device (3) for sealing the gasification chamber after gasification is completed; The carbon dioxide pressurizing injection device (4) is connected to the carbon dioxide cooling storage device (2), and the carbon dioxide pressurizing injection device (4) pressurizes and injects the cooled and stored carbon dioxide into the gas injection well.
2. The active cooling device for underground coal gasification according to claim 1, characterized in that: Also includes: An intermediate mixing container (5) is connected to the carbon dioxide cooling and storage device (2) upstream and to the carbon dioxide pressurizing and injection device (4) downstream. The intermediate mixing container (5) is used to mix the cooled and stored carbon dioxide and the foaming agent.
3. The active cooling device for underground coal gasification according to claim 1, characterized in that: The gasification cavity sealing device (3) comprises: A high molecular weight carbonaceous filler (31) is provided in the annular gap generated during the gasification process; The casing head (32) is arranged at the top end of the gasification chamber (6).
4. The active cooling device for underground coal gasification according to claim 1, characterized in that: It also includes a gas processing device (7) for processing the gas in the gasification product.
5. The active cooling device for underground coal gasification according to claim 2, characterized in that: It also includes a foaming agent supply device (8) connected to the intermediate mixing container (5), and the foaming agent supply device (8) is used to supply the foaming agent.
6. The active cooling device for underground coal gasification according to claim 1, characterized in that: The carbon dioxide cooling and storage device (2) may include a connected carbon dioxide cooling device (21) and a carbon dioxide storage device (22), wherein the carbon dioxide cooling device (21) is connected to the carbon dioxide capture device (1), and the carbon dioxide storage device (22) is connected to the carbon dioxide pressurizing and injection device (4).