An apparatus and method for monitoring the ignition and operational status of underground coal gasification.

Abstract

This invention discloses a device and method for monitoring the ignition and operational status of underground coal gasification. The device includes a heat flux meter and a temperature measuring device symmetrically arranged in an annular cavity between a continuous tube and an injection pipe. The heat-conducting component of the heat flux meter and the temperature probe of the temperature measuring device are both on the same plane as the combustion head of the continuous tube, allowing for real-time acquisition of heat flux density and temperature data in the underground gasification ignition area. Combining these two data points enables timely determination of the coal seam ignition status, shortening ignition time and achieving efficient ignition. This method, by using both heat flux density and temperature as criteria for coal seam combustion status, can more efficiently and promptly determine whether the coal seam has achieved self-sustaining combustion. If ignition is successful, gas injection can be stopped promptly; if ignition fails, the injection point can be moved back for secondary ignition, saving ignition costs.

Description

Technical Field

[0001] This invention belongs to the field of underground coal gasification technology, specifically relating to a device and method for monitoring the ignition and operation status of underground coal gasification. Background Technology

[0002] Underground coal gasification technology enables controlled combustion of coal in situ, converting it into combustible gas through thermal and chemical processes. This transforms traditional physical coal mining into chemical gas extraction, offering advantages such as low production costs, high safety, and good environmental benefits. This technology has broad application prospects in the mining and utilization of low-quality (high sulfur, high ash), steeply inclined, thin, deep coal seams, and residual coal that is economically unminable using conventional techniques.

[0003] The primary condition for underground coal gasification technology is solving the problem of coal seam ignition; the successful implementation of the ignition operation is crucial to the success of underground gasification. Current underground coal gasification technologies generally use coal seam temperature measurement to determine whether the coal seam has achieved self-sustaining combustion, thus judging the success of underground gasification. However, in practical scenarios, temperature measurement in underground gasifiers faces many problems, such as the difficulty in arranging temperature measuring devices, and the inherent errors in temperature measurements, making it impossible to accurately characterize the coal seam ignition status, and sometimes even making it impossible to determine the coal seam ignition status through temperature measurement alone. Summary of the Invention

[0004] Technical problem solved: In view of the above-mentioned technical problems, the present invention provides a device and method for monitoring the underground gasification ignition and operation status of coal, which can monitor the underground gasification status in real time and judge the coal seam combustion status in a timely and effective manner.

[0005] Technical solution: A device for monitoring the ignition and operation status of underground coal gasification, comprising a heat flow meter and a temperature measuring device axially symmetrically arranged in an annular cavity between a continuous pipe and an injection pipe;

[0006] The heat flow meter includes a shell, a front-end heat-conducting component, a rear-end heat-conducting component, a first thermocouple, a second thermocouple, thermocouple signal lines, a thermocouple protection tube, a partition, a cooling water inlet pipe, and a cooling water outlet pipe. The shell is cylindrical and arranged parallel to the axial direction of the continuous tube, with its front end face parallel to the front end face of the gas injection pipe. The front-end and rear-end heat-conducting components are arranged side-by-side, with their radial widths both smaller than the inner diameter of the shell, and the front end face of the front-end heat-conducting component is in contact with the front inner wall of the shell. The first and second thermocouples are respectively located at the front end and rear central axis of the rear-end heat-conducting component. Each thermocouple is connected to the ground control center via thermocouple signal lines. The thermocouple protection tube is located on the central axis of the outer shell, with one end attached to the second thermocouple and the other end connected to the ground control center, serving to accommodate the thermocouple signal lines. Two partitions are provided, parallel to each other, located outside the sidewall of the thermocouple protection tube. Their front ends are connected to the rear end face of the rear heat-conducting component, their rear ends are connected to the rear inner wall of the outer shell, and their sides are connected to the inner wall of the outer shell. The cooling water inlet pipe and cooling water outlet pipe both penetrate the rear end of the outer shell, respectively connecting the cavities formed by the corresponding partitions and the inner wall of the outer shell.

[0007] The temperature measuring device includes a temperature probe and a temperature signal line. The temperature probe is located on the front end face of the continuous tube, and the two ends of the temperature signal line are connected to the temperature probe and the ground control center, respectively.

[0008] Preferably, a metal gasket is provided between the front-end heat-conducting component and the rear-end heat-conducting component.

[0009] Preferably, the metal gasket is made of a soft metal with a thermal conductivity λ>200W / (m℃) and a Boolean hardness HB<50.

[0010] Preferably, the front and rear end faces of the rear heat conductor are provided with radial channels and axial through holes away from the central axis, and the radial channels and axial through holes are interconnected. The radial channels and axial through holes are used to accommodate thermocouple signal lines.

[0011] Preferably, the continuous pipe is provided with a main cooling water pipe and an injection cooling water pipe, the injection cooling water pipe is arranged around the outer wall of the injection pipe, and the main cooling water pipe is connected to the injection cooling water pipe and the cooling water inlet pipe through a three-way valve.

[0012] Preferably, the outer shell of the heat flow meter is connected to the inner wall of the continuous tube by a bracket.

[0013] Preferably, the thermocouple protection tube is made of PVC pipe.

[0014] Preferably, the diameter of the continuous tube is 72~84mm.

[0015] A method for monitoring the ignition and operational status of underground coal gasification includes the following steps:

[0016] Step 1: When the gas is introduced into the gas injection pipe, turn on the temperature measuring device and heat flux meter to collect the temperature and heat flux density data at the ignition point and transmit them to the ground control center.

[0017] Step 2: Maintain gas injection and start ignition. Once the temperature and heat flux density data stabilize, transmit the data to the ground control center and take the average value as T1 and Q1.

[0018] Step 3: Continuously monitor the temperature and heat flux density at the ignition point. When the temperature rise reaches 20%~50% of T1, the temperature criterion is considered to be met; when the heat flux density increase reaches 20%~50% of Q1, the heat flux criterion is considered to be met; and when either the temperature criterion or the heat flux criterion is met, the coal seam is considered to be successfully ignited.

[0019] Preferably, the temperature criterion and heat flux density criterion vary with hydrogeological conditions, coal type, and horizontal drilling inclination angle.

[0020] Beneficial effects: In this invention, the heat conduction component of the heat flow meter and the temperature measuring probe of the temperature measuring device are both on the same plane as the combustion head of the continuous tube, which can obtain the heat flow density and temperature data of the underground gasification ignition area in real time. At the same time, by combining the two, the coal seam ignition status can be judged in a timely manner, shortening the ignition time and achieving efficient ignition.

[0021] This invention integrates a heat flux meter and a temperature measuring device onto a continuous tube, reducing equipment size and simplifying operation. It enables real-time monitoring of underground gasification ignition and operational status. By using both heat flux density and temperature as criteria for coal seam combustion, this method can more efficiently and promptly determine whether the coal seam has achieved self-sustaining combustion. If ignition is successful, gas injection can be stopped promptly; if ignition fails, the injection point can be moved back for a second ignition, saving ignition costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the underground gasification ignition and operation status monitoring device in a horizontal well;

[0023] Figure 2 This is a schematic diagram of the heat flow meter.

[0024] The numbers in the diagram represent the following: 1. Continuous pipe; 2. Gas injection pipe; 3. Heat flow meter; 4. Temperature probe; 5. Temperature signal line; 6. Main cooling water pipe; 7. Gas injection cooling water pipe; 8. Three-way valve; 3-1. Outer shell; 3-2. Front heat conductor; 3-3. Rear heat conductor; 3-4. First thermocouple; 3-5. Second thermocouple; 3-6. Thermocouple signal line; 3-7. Thermocouple protection tube; 3-8. Baffle; 3-9. Cooling water inlet pipe; 3-10. Cooling water outlet pipe; 3-11. Metal gasket; 3-12. Bracket; 3-3-1. Radial channel; 3-3-2. Axial through hole. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] In the description of this invention, it should be understood that the terms "front end," "rear end," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing the 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. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of the invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0027] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. After reading the above content, various modifications and substitutions to the present invention will be apparent to those skilled in the art. Within the scope of the inventive concept, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, a device for monitoring the ignition and operation status of underground coal gasification includes a heat flow meter 3 and a temperature measuring device axially symmetrically arranged in an annular cavity between a continuous tube 1 and an injection tube 2. The diameter of the continuous tube 1 is 72~84mm, and 84mm is used in this embodiment. The injection tube 2 and an ignition device located at the center of the front end of the continuous tube 1 are installed inside the tube for integrated underground gasification ignition.

[0030] The temperature measuring device includes a temperature probe 4 and a temperature signal line 5. The temperature probe 4 is located on the front end face of the continuous tube 1, and the two ends of the temperature signal line 5 are respectively connected to the temperature probe 4 and the ground control center.

[0031] like Figure 2 As shown, the heat flow meter 3 includes a housing 3-1, a front heat-conducting component 3-2, a rear heat-conducting component 3-3, a first thermocouple 3-4, a second thermocouple 3-5, a thermocouple signal line 3-6, a thermocouple protection tube 3-7, a partition 3-8, a cooling water inlet pipe 3-9, and a cooling water outlet pipe 3-10.

[0032] The outer casing 3-1 is cylindrical and is arranged axially parallel to the continuous tube 1, with its front end face parallel to the front end face of the gas injection tube 2. The outer casing 3-1 is connected to the inner wall of the continuous tube 1 by spaced-apart supports 3-12.

[0033] The front-end heat-conducting component 3-2 and the rear-end heat-conducting component 3-3 are arranged side by side, with their radial widths both smaller than the inner diameter of the outer shell 3-1. The front-end face of the front-end heat-conducting component 3-2 is fitted to the front inner wall of the outer shell 3-1. A metal gasket 3-11 is provided between the front-end heat-conducting component 3-2 and the rear-end heat-conducting component 3-3 to reduce measurement errors caused by possible gaps at the connection of the heat-conducting components. The metal gasket 3-11 is made of a soft metal with a thermal conductivity λ>200W / (m℃) and a Boolean hardness HB<50. The rear-end heat-conducting component 3-3 has radial channels 3-3-1 on its front and rear end faces and an axial through hole 3-3-2 away from the central axis. The radial channels 3-3-1 and the axial through hole 3-3-2 are interconnected. The radial channels 3-3-1 and the axial through hole 3-3-2 are used to accommodate the thermocouple signal wire 3-6. The first thermocouple 3-4 and the second thermocouple 3-5 are respectively located at the front end and the rear central axis of the rear heat-conducting component 3-3, and are respectively connected to the ground control center through thermocouple signal lines 3-6.

[0034] The thermocouple protection tube 3-7 is made of PVC pipe and is located on the central axis of the outer shell 3-1. One end is attached to the second thermocouple 3-5, and the connection between it and the rear heat conductor 3-3 is waterproofed to prevent cooling water from seeping in. The other end is connected to the ground control center to accommodate the thermocouple signal line 3-6. Two partition plates 3-8 are provided, parallel to each other, on the outside of the side wall of the thermocouple protection tube 3-7. Their front ends are connected to the rear end face of the rear heat conductor 3-3, their rear ends are connected to the rear inner wall of the outer shell 3-1, and their sides are connected to the inner wall of the outer shell 3-1. The partition plates 3-8 divide the internal space of the heat flow meter 3 into an inlet channel and an outlet channel. Combined with the annular channel formed between the front heat conductor 3-2, the rear heat conductor 3-3, and the outer shell 3-1, cooling water enters the inlet channel through the cooling water inlet pipe 3-9, cools the heat conductors around the annular channel, and then flows out through the outlet channel via the cooling water outlet pipe 3-10.

[0035] The cooling water inlet pipe 3-9 and cooling water outlet pipe 3-10 both penetrate the rear end of the outer casing 3-1, respectively connecting the corresponding partition 3-8 and the cavity formed by the inner wall of the outer casing 3-1. Figure 1 As shown, the continuous pipe 1 is provided with a main cooling water pipe 6 and an air injection cooling water pipe 7. The air injection cooling water pipe 7 surrounds the outer pipe wall of the air injection pipe 2 and can cool the air injection pipe 2. The main cooling water pipe 6, the air injection cooling water pipe 7, and the cooling water inlet pipe 3-9 are connected by a three-way valve 8. In this embodiment, the three-way valve 8 is a three-way CNC valve.

[0036] Example 2

[0037] The detection method based on the device for monitoring the underground coal gasification ignition and operating status in Example 1 includes the following steps:

[0038] Step 1: When the gas is introduced into the gas injection pipe 2, turn on the temperature measuring device and heat flux meter 3 to collect the temperature and heat flux density data at the ignition point and transmit them to the ground control center.

[0039] Step 2: Maintain gas injection and start ignition. Once the temperature and heat flux density data stabilize, transmit the data to the ground control center and take the average value as T1 and Q1.

[0040] Step 3: Continuously monitor the temperature and heat flux density at the ignition point. When the temperature rise reaches 30% of T1, the temperature criterion is considered to be met; when the heat flux density increase reaches 30% of Q1, the heat flux criterion is considered to be met; and when either the temperature criterion or the heat flux criterion is met, the coal seam is considered to be successfully ignited.

[0041] The temperature criterion and heat flux density criterion are affected by hydrogeological conditions, coal type and horizontal drilling inclination angle, and can be taken in the range of 20% to 50% in this invention.

Claims

1. A method for monitoring the ignition and operational status of underground coal gasification equipment, characterized in that, The device includes a heat flow meter (3) and a temperature measuring device axially symmetrically arranged in an annular cavity between the continuous tube (1) and the gas injection pipe (2); the heat flow meter (3) includes a shell (3-1), a front heat-conducting element (3-2), a rear heat-conducting element (3-3), a first thermocouple (3-4), a second thermocouple (3-5), a thermocouple signal line (3-6), a thermocouple protection tube (3-7), a partition (3-8), a cooling water inlet pipe (3-9), and a cooling water outlet pipe (3-10); the shell (3-1) is cylindrical and arranged axially parallel to the continuous tube (1), with its front end face parallel to the front end face of the gas injection pipe (2); the front heat-conducting element (3-2) and the rear heat-conducting element (3-3) are arranged side by side, with their radial widths both smaller than the inner diameter of the shell (3-1), and the front end face of the front heat-conducting element (3-2) is attached to the inner wall of the front end of the shell (3-1); the first thermocouple (3-4) 3-4) and the second thermocouple (3-5) are respectively located at the front end and the rear central axis of the rear heat-conducting component (3-3), and are respectively connected to the ground control center through thermocouple signal lines (3-6); the thermocouple protection tube (3-7) is located on the central axis of the outer shell (3-1), with one end attached to the second thermocouple (3-5) and the other end connected to the ground control center, and is used to accommodate the thermocouple signal line (3-6); the partition (3-8) has two pieces, which are arranged parallel to each other outside the side wall of the thermocouple protection tube (3-7), with its front end connected to the rear end face of the rear heat-conducting component (3-3), its rear end connected to the rear inner wall of the outer shell (3-1), and its two sides connected to the inner wall of the outer shell (3-1); the cooling water inlet pipe (3-9) and the cooling water outlet pipe (3-10) both penetrate the rear end of the outer shell (3-1), and respectively connect the cavity formed by the corresponding partition (3-8) and the inner wall of the outer shell (3-1); The temperature measuring device includes a temperature probe (4) and a temperature signal line (5). The temperature probe (4) is located on the front end face of the continuous tube (1), and the two ends of the temperature signal line (5) are connected to the temperature probe (4) and the ground control center, respectively. The method includes the following steps: Step 1: When the gas is introduced into the gas injection pipe (2), turn on the temperature measuring device and heat flow meter (3) to collect the temperature and heat flow density data at the ignition point and transmit them to the ground control center; Step 2: Maintain gas injection and start ignition. Once the temperature and heat flux density data stabilize, transmit the data to the ground control center and take the average value as T1 and Q1. Step 3: Continuously monitor the temperature and heat flux density at the ignition point. When the temperature rise reaches 20%~50% of T1, the temperature criterion is considered to be met; when the heat flux density increase reaches 20%~50% of Q1, the heat flux density criterion is considered to be met; and when either the temperature criterion or the heat flux density criterion is met, the coal seam is considered to be successfully ignited.

2. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 1, characterized in that, The temperature criterion and heat flux density criterion vary with hydrogeological conditions, coal type, and horizontal drilling inclination angle.

3. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 1, characterized in that, A metal gasket (3-11) is provided between the front heat-conducting component (3-2) and the rear heat-conducting component (3-3).

4. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 3, characterized in that, The metal gasket (3-11) is made of a soft metal with a thermal conductivity λ>200W / (m℃) and a Boolean hardness HB<50.

5. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 1, characterized in that, The rear heat-conducting component (3-3) has radial channels (3-3-1) on its front and rear ends and axial through holes (3-3-2) on its far side from the central axis. The radial channels (3-3-1) and axial through holes (3-3-2) are interconnected. The radial channels (3-3-1) and axial through holes (3-3-2) are used to accommodate thermocouple signal wires (3-6).

6. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 1, characterized in that, The continuous pipe (1) is provided with a main cooling water pipe (6) and an air injection cooling water pipe (7). The air injection cooling water pipe (7) is arranged around the outer wall of the air injection pipe (2). The main cooling water pipe (6) is connected to the air injection cooling water pipe (7) and the cooling water inlet pipe (3-9) through a three-way valve (8).

7. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 1, characterized in that, The outer shell (3-1) of the heat flow meter (3) is connected to the inner wall of the continuous tube (1) via a bracket (3-12).

8. The method for monitoring the ignition and operation status of underground coal gasification as described in claim 1, characterized in that, The thermocouple protection tube (3-7) is made of PVC pipe.

9. The method for monitoring the ignition and operational status of underground coal gasification as described in claim 1, characterized in that, The diameter of the continuous tube (1) is 72~84mm.

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