Test device, system and method for simulating lump coal thermal stripping under coal underground gasification condition

Abstract

The invention discloses a test device, a test system and a test method for simulating lump coal thermal stripping under a coal underground gasification condition. The test device comprises a heating furnace, a coal briquette clamping tool, a suspension tool and an online thermobalance. A furnace body of the heating furnace is provided with a heating cavity, a gasifying agent inlet and a synthesis gas outlet; the coal briquette clamping tool is arranged in the heating cavity and used for clamping a coal briquette, and only part of the bottom surface or the whole bottom surface of the coal briquette is exposed out of the coal briquette clamping tool; the suspension tool penetrates through the furnace body, and the bottom end of the suspension tool extends into the heating cavity and is connected with the coal briquette clamping tool; the on-line thermobalance is arranged outside the heating furnace and is connected with the top end of the suspension tool; the heating furnace is provided with a heating element, and the heating element is arranged below the coal briquette clamping tool; the top wall and the side walls of the coal briquette clamping tool are made of thermal insulation materials, so that only the bottom face of the coal briquette can be heated. According to the invention, UCG reaction conditions can be simulated, and thermal stripping parameters and weight loss rate of coal briquettes can be measured on line.

Description

Technical Field

[0001] The invention belongs to the technical field of underground coal gasification, and in particular relates to a test device and a test method for simulating thermal spalling of lump coal under underground coal gasification conditions. Background Art

[0002] The cracking and spalling characteristics of coal in coal seams are important influencing indicators of the reaction rate of UCG (Underground Goal Gasification). During the early field experiments of underground coal gasification, domestic and foreign researchers found that the coal seam at the top of the gasification channel would spall and break during the reaction process. The thermal spalling of the coal seam will cause the expansion of the gasification channel, generate a gasification cavity and form a new gasification zone (gravel zone) at the bottom of the coal seam spalling. The top of the heating chamber and the gravel zone are the main sites for pyrolysis, combustion and heterogeneous gasification reactions in the UCG process, while the homogeneous reaction mainly occurs in the gasification cavity.

[0003] The gravel zone formed by the accumulation of flaked coal blocks on the bottom of the heating chamber is mainly composed of lump raw coal, coal coke, ash and rocks that do not participate in the gasification reaction above the centimeter level. The formation of this gasification zone can promote the UCG reaction. In addition, the spalling of the coal seam will also cause the expansion of the gasification channel to produce cavities. In the cavity, the pyrolysis and gasification products may undergo secondary oxidation with the oxygen-containing gasifier, resulting in a decrease in the quality of the synthesis gas. It can be seen that the thermal spalling of the coal seam has an important influence on the quality of the gas produced by UCG gasification, and obtaining the formation mechanism of thermal spalling during underground coal gasification has important guiding significance for the application of UCG technology. However, there is currently no unified theoretical model to explain the spalling and fragmentation of coal seams during the UCG process.

[0004] Since the thermal spalling behavior of coal involves the intersection of multiple disciplines such as coal, heat, chemistry and geology, the phenomena observed in field experiments still need scientific mechanistic interpretation. Therefore, in recent years, the research on underground coal gasification has gradually developed towards small-scale laboratory simulation. Through the early miniaturization test, the gasification reaction parameters, coal seam cracking and thermal spalling characteristics of the coal seam can be obtained. There are few experimental studies on the thermal cracking and spalling of lump coal in China. At present, most of the UCG test benches (such as the test devices mentioned in Chinese patents CN101586915 and CN111487020) cannot directly measure the parameters such as the coal block spalling rate and the coal seam weight loss rate during the reaction process. In addition, the heating furnace for simulating the UCG reaction in the laboratory is also difficult to achieve the reaction condition in which only the bottom of the coal seam is heated during the actual reaction process. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a test device and a test method for simulating thermal spalling of lump coal under underground coal gasification conditions, which can simulate UCG reaction conditions and measure the weight loss rate and thermal spalling parameters of coal blocks online.

[0006] According to a first aspect of the present invention, there is provided a test device for thermal spalling of coal blocks under conditions of underground coal gasification, comprising a heating furnace, a furnace body of the heating furnace having a heating chamber, a gasifying agent inlet and a syngas outlet, the gasifying agent inlet and the syngas outlet being connected to the heating chamber, respectively; the test device also comprises a coal block clamping tool, a hanging tool and an online thermobalance; the coal block clamping tool is arranged in the heating chamber to clamp the coal block, and only part or all of the bottom surface of the coal block is exposed outside the coal block clamping tool; the hanging tool passes through the furnace body, and the bottom end of the hanging tool extends into the heating chamber and is connected to the coal block clamping tool; the online thermobalance is arranged outside the heating furnace, and the online thermobalance is connected to the top of the hanging tool; the heating furnace is provided with a heating element, and the heating element is arranged below the coal block clamping tool; the top wall and side walls of the coal block clamping tool are made of insulating material so that only the bottom surface of the coal block can be heated.

[0007] According to a second aspect of the present invention, there is provided a test system for simulating thermal spalling of coal blocks under underground coal gasification conditions, the test system comprising a gasifying agent supply mechanism and a gas analyzer as described above; the gasifying agent supply mechanism is connected to a gasifying agent inlet of a heating furnace to output the gasifying agent to a heating chamber of the heating furnace; the gas inlet of the gas analyzer is connected to a synthesis gas outlet of the heating furnace.

[0008] According to a third aspect of the present invention, there is provided a test method for the test device for simulating thermal spalling of lump coal under underground coal gasification conditions, comprising the following steps:

[0009] Load the coal block into the coal block holding tool, connect the coal block holding tool to the online thermobalance through the hanging tool, close the door of the heating furnace, and perform an airtightness test on the heating furnace;

[0010] After the airtightness test is passed, the gasifying agent supply mechanism outputs the gasifying agent required for the UCG reaction into the heating chamber;

[0011] The heating element is started until the temperature of the heating chamber of the heating furnace reaches the set temperature. During this process, the mass of the coal block is monitored in real time by an online thermal balance, and a curve of the weight loss rate of the coal block changing with time is drawn and displayed. The thermal spalling characteristic parameters of the coal type to which the coal block belongs are obtained by analyzing the curve.

[0012] The present invention has at least the following advantages and features:

[0013] 1. The coal block holding tool of the test device of the embodiment of the present invention is made of insulating material, and only part or all of the bottom surface of the coal block is exposed outside the coal block holding tool, and the other surfaces of the coal block are covered by the coal block holding tool. Only the bottom surface of the coal block is heated, thereby simulating the physical condition of single-side heating of the coal seam during the UCG reaction process;

[0014] 2. The coal block of the embodiment of the present invention is connected to the online thermobalance through a suspension tool, so that the mass of the coal block can be measured in real time during the test, and the weight loss rate curve and thermal spalling characteristic parameters of the coal block under single-side heating conditions can be obtained by calculation;

[0015] 3. The test device of the embodiment of the present invention is provided with an observation window to facilitate observation of the phenomena of coal block peeling and coal block cracking during the gasification reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of an experimental system for simulating thermal spalling of lump coal under underground coal gasification conditions according to an embodiment of the present invention is shown.

[0017] Figure 2 A schematic flow chart of a test method for thermal spalling of lump coal under simulated underground coal gasification conditions according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] In order to make the structural design of the present invention clearer, the following Figure 1 , Figure 2 It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] In the description of the present invention, it is necessary to understand that the terms "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] See also Figure 1 The test system for thermal spalling of lump coal under conditions of simulating underground coal gasification according to an embodiment of the present invention comprises a gasifying agent supply mechanism, a gas analyzer, and a test device for thermal spalling of lump coal under conditions of simulating underground coal gasification.

[0021] The test device for simulating thermal spalling of lump coal under underground coal gasification conditions comprises a heating furnace 11, a temperature measuring element 12, a coal block clamping tool 13, a hanging tool 14, and an online thermal balance 15.

[0022] The furnace body 11A of the heating furnace 11 has a heating chamber 110, a gasifying agent inlet 111 and a synthesis gas outlet 112. The gasifying agent inlet 111 and the synthesis gas outlet 112 are respectively connected to the heating chamber 110. An observation window 113 is provided on the side of the furnace body 11A.

[0023] In this embodiment, the size of the heating chamber 110 is 400×300×300 mm. The size of the observation window 113 is 150*50 mm, and the distance from the bottom of the heating chamber is 50 mm. The observation window 113 is made of high-strength quartz glass. During the test, the thermal spalling and thermal cracking characteristics of the coal block can be observed through the observation window.

[0024] The temperature measuring element 12 is installed on the side of the furnace body 11A, and is used to measure the temperature of the heating chamber 110. In this embodiment, the temperature measuring element 12 is a thermocouple.

[0025] The heating furnace 11 is also provided with a heating element 114. In this embodiment, the heating element 114 is a heating plate with silicon carbon rods, and the heating plate is arranged on the bottom surface of the heating chamber 110. In some specific embodiments, a plurality of silicon carbon rods are laid on the bottom of the heating plate 114, and the heating power of each silicon carbon rod is controlled by a computer. The computer analyzes the temperature in the furnace measured by the temperature measuring element 12 to reasonably adjust the reaction temperature in the furnace.

[0026] The coal block clamping tool 13 is arranged in the heating chamber 110 to clamp the coal block 9 as the coal sample, and the heating element 114 is located below the coal block clamping tool 13. Only part of the bottom surface or the entire bottom surface of the coal block is exposed to the outside of the coal block clamping tool 13, and the remaining surfaces (all side surfaces and top surfaces) are covered by the coal block clamping tool. The top wall and side walls of the coal block clamping tool 13 are made of insulating material. The "made of insulating material" mentioned here can mean that the top wall and side walls of the coal block clamping tool 13 are made of a single insulating material, or that the top wall and side walls of the coal block clamping tool 13 contain an insulating layer made of insulating material, so that only the bottom surface of the coal block is heated, thereby simulating the UCG reaction conditions.

[0027] The angle deviation between the bottom surface of the coal block 9 and the bedding plane of the coal block 9 (ie the bedding plane of the coal seam to which the coal block belongs) does not exceed 10°. Preferably, the bottom surface of the coal block 9 and the bedding plane of the coal block 9 remain parallel.

[0028] In this embodiment, the coal block clamping tool 13 includes a top wall 131, a side wall 132 and a bottom wall 133. The side wall 132 surrounds the side of the coal block 9. The top and bottom ends of the side wall 132 are respectively connected to the top wall 131 and the bottom wall 133. The bottom wall 133 is provided with a through hole to expose a portion of the bottom surface of the coal block 9.

[0029] In this embodiment, the shape of the coal block holding tool 13 is a hexahedron with an outer size of 300 mm×210 mm×150 mm. The main body of the coal block holding tool 13 is made of heat-resistant stainless steel SS-410, and the four side surfaces and the outer side of the top surface of the main body are also provided with an insulation layer, which is made of ceramic fiber insulation material and has a thickness of 15 mm. In this way, only the bottom surface of the coal block 9 is exposed to the hot air flow to simulate the heating of the top plate during the actual UCG reaction process.

[0030] During the test, the large coal was first cut into a size suitable for the coal holding tool 13 by wire cutting. When cutting the coal, the exposed surface should be kept parallel to the bedding plane of the coal. In addition, the exposed surface is equivalent to the top of the cavity in the UCG process. The purpose of the heat insulation between the coal and the coal holding tool is to heat the coal mainly from the exposed bottom surface.

[0031] The hanging tool 14 passes through the furnace body 11A, and the bottom end of the hanging tool 14 extends into the heating chamber 110 and is connected to the coal block clamping tool 13.

[0032] There is a gap between the suspension tool 14 and the furnace body through hole for it to pass through, and the gap is greater than 1mm and less than 3mm to ensure that the suspension tool 14 does not contact the furnace body 11A during the weight loss of the coal block. Furthermore, a small amount of asbestos material is filled in the gap to prevent external air from entering the furnace body.

[0033] The online thermobalance 15 is arranged outside the heating furnace 11, and is connected to the top of the suspension tool 14 to monitor the mass change and the peeling rate of the coal block 9. When the suspension tool 14 passes through the furnace body 11A, care should be taken to prevent the online thermobalance 15 from contacting any solid object to obtain a more accurate measurement result. In this embodiment, the accuracy of the online thermobalance is 0.1g, and the data is read once every 1s and recorded in the processor of the online thermobalance 15, that is, the real-time mass of the coal is measured by the online thermobalance with a sampling frequency of 1s / time. During the experiment, the weight loss rate of the coal block is calculated in real time by the processor of the online thermobalance 15, and the weight loss rate of the coal block (unit: g / s) is used as the Y axis, and the time (unit: s) is used as the X axis to obtain the weight loss rate curve of the coal block. By analyzing the weight loss rate curve, the moment when the weight loss rate exceeds the set threshold (in some specific implementations, the threshold is set to 0.5g / s) and the weight loss rate at that moment are organized into a set of important parameters for the test: in the form of (thermal spalling moment, weight loss rate at the thermal spalling moment), thus obtaining the thermal spalling characteristic parameters of this type of coal.

[0034] Furthermore, a fixing bracket 17 is provided on the top of the furnace body 11A, and the online thermobalance 15 is installed on the fixing bracket 17 .

[0035] The gasifying agent supply mechanism is connected to the gasifying agent inlet 111 of the heating furnace 11, and is used to output the gasifying agent to the heating chamber 110 of the heating furnace 11. In this embodiment, the gasifying agent supply mechanism includes a nitrogen supply device, a carbon dioxide supply device, an oxygen supply device, and a water supply device, and the nitrogen supply device, the carbon dioxide supply device, the oxygen supply device, and the water supply device are respectively used to selectively output corresponding gas or water to the heating chamber 110. Figure 1 Only the high-pressure nitrogen tank 20 and the water supply device 22 are shown as examples. A pressure reducing regulating valve 281, a gas flow meter 282, and a one-way valve 283 are provided on the pipeline connecting the high-pressure nitrogen tank to the gasifying agent inlet 111. The nitrogen required for simulating UCG enters the furnace body from the high-pressure nitrogen tank 20 through the pressure reducing regulating valve 281, the flow meter 282, and the one-way valve 283, filling the entire heating chamber. The structure of the carbon dioxide supply device and the oxygen supply device are similar to those of the nitrogen supply device, which are not shown in the figure. The water vapor required for UCG is provided by the water supply device 22. The purified water is precisely controlled by a peristaltic pump and enters the heating furnace for gasification before being filled into the reaction space.

[0036] The gas inlet of the gas analyzer 21 is connected to the synthesis gas outlet 112 of the heating furnace 11. In this embodiment, the test system further includes a synthesis gas filter device 23 and a coal tar purification device 24. The inlet of the synthesis gas filter device 23 is connected to the synthesis gas outlet 112 of the heating furnace, and the outlet of the synthesis gas filter device 23, the coal tar purification device 24 and the gas inlet of the gas analyzer 21 are connected in sequence. As the UCG reaction proceeds, the synthesis gas is discharged from the synthesis gas outlet 112 and enters the gas analyzer 12 via the synthesis gas filter device 23 and the coal tar purification device 24.

[0037] The test process of the test system for simulating thermal spalling of lump coal under underground coal gasification conditions according to an embodiment of the present invention is roughly as follows:

[0038] Put the coal block 9 (i.e., the coal sample) into the coal block holding tool 13, connect the coal block holding tool 13 to the online thermobalance 15 through the hanging tool 14, close the door of the heating furnace 11, and perform an airtightness test on the heating furnace 11;

[0039] After the airtightness test is passed, the gasifying agent supply mechanism outputs the gasifying agent required for the UCG reaction into the heating chamber 110;

[0040] The heating element 114 is started until the temperature of the heating chamber 110 of the heating furnace 11 reaches the set temperature. During this process, the quality of the coal block is monitored in real time by the online thermobalance 15. The online thermobalance 15 draws and displays a curve of the weight loss rate of the coal block changing with time, and the thermal spalling characteristic parameters of the coal type to which the coal block belongs are obtained by analyzing the curve.

[0041] The above analysis of the curve to obtain the thermal spalling characteristic parameters includes: taking the moment when the weight loss rate exceeds the set threshold as the thermal spalling moment (a thermal spalling event occurs at the thermal spalling moment), recording all thermal spalling moments and the weight loss rate at each thermal spalling moment as the thermal spalling characteristic parameters of the coal type to which the coal block belongs. The calculation formula for the weight loss rate is:

[0042]

[0043] In the formula,

[0044] Weight loss rate, g / s

[0045] M2: The mass of the coal block at the current sampling moment, in g;

[0046] M1: The mass of the coal block at the last sampling moment, in g

[0047] δT: sampling interval, unit s

[0048] The airtightness test includes the following steps: using an inert gas to purge the heating chamber 110 of the heating furnace, and monitoring the oxygen content concentration in the heating chamber 110 through a gas analyzer 21 until the oxygen content concentration is lower than a predetermined value to confirm that the airtightness test has passed.

[0049] The following combination Figure 2 A specific implementation manner will be described in more detail on the test process of the test system for simulating thermal spalling of lump coal under underground coal gasification conditions according to an embodiment of the present invention.

[0050] Before the test, check and confirm that the online thermobalance 15, gasifying agent supply mechanism and gas analyzer 21 are working properly, and the filler in the synthesis gas filter 23 is not invalid. Put the processed coal block 9 into the coal block clamping tool 13, connect the coal block clamping tool 13 to the online thermobalance 15 through the hanging tool 14, close the furnace door, and conduct an airtightness test.

[0051] Subsequently, N2 with a volume flow rate of 5 L / min was used to purge the heating chamber 110 of the furnace body, and the oxygen content concentration in the heating chamber 110 was monitored by the gas analyzer 21 until the oxygen content concentration was lower than 1%. This working condition was maintained for 10 minutes to confirm that the air tightness of the system was good. After the air tightness test was passed, N2, CO2, H2O, O2 and other gases required for the UCG reaction were introduced into the heating chamber 110.

[0052] The reactor is heated at a constant heating rate until the set temperature is reached (the set temperatures are 500°C, 700°C, and 900°C, respectively). Since the coal block 9 is surrounded and covered with insulation materials, the coal block 9 is mainly heated at the bottom. This heating method simulates the heating conditions of the top plate of the combustion zone of the actual UCG reaction. When the temperature rises to 100-200°C, the moisture and part of the CO2 inside the coal block 9 will be released from the coal block. When the temperature rises to 600°C-900°C, the coal block 9 undergoes a pyrolysis reaction inside the coal block clamping tool 13, releasing volatiles such as CH4, CO, H2, and tar. When the temperature rises to 900°C, the pyrolysis reaction of the coal block 9 tends to be completed. The reaction in the heating chamber varies depending on the gas components introduced. In particular, when only N2 is introduced, the coal block only undergoes pyrolysis reaction and no longer undergoes gasification reaction; when the introduced gas is CO2, H2O and O2, the coal sample undergoes gasification reaction in addition to pyrolysis reaction.

[0053] Since coal seams belong to sedimentary rock systems, there are differences in the coal quality components of different layers, and there are also differences in the rates of releasing volatiles and tar. This leads to interlayer stress caused by the release of volatiles during the reaction process. The process of releasing high-volatile substances will form many pores inside the coal block 9, which greatly weaken the internal strength structure of the coal block 9; as the weight loss continues, the high-volatile coal blocks are eventually insufficient to withstand the tensile stress caused by the gravity of the small coal blocks at the bottom, and thermal peeling of the coal blocks occurs. During the heating process, the test system of the embodiment of the present invention can monitor and record the quality of the coal sample in real time. When the small coal blocks peel off from the bottom of the coal block 9, an obvious weight loss peak will appear on the weight loss rate curve, and the weight loss peak is characterized by a step signal. The basis for the occurrence of the thermal peeling event is that the weight loss rate at the step signal exceeds 0.5g / s.

[0054] Since the volatile components of different types of coal are significantly different, before the actual UCG reaction, the test system of the embodiment of the present invention can be used to analyze the characteristic parameters of the thermal exfoliation rate of the coal quality to provide a technical reference for the reaction channel design of the actual UCG process.

[0055] When the measurement part of the test is finished, the gas introduced into the system is converted to N2, and the gasification reaction is finished. The heating element 114 is stopped, and after the heating furnace is cooled to room temperature, the reacted coal block 9 is taken out.

Claims

1. A test device for simulating thermal spalling of lump coal under underground coal gasification conditions, comprising a heating furnace, wherein the furnace body of the heating furnace has a heating chamber, a gasifying agent inlet and a syngas outlet, wherein the gasifying agent inlet and the syngas outlet are respectively connected to the heating chamber; characterized in that: The test device also includes a coal block holding tool, a suspension tool and an online thermobalance; The coal block clamping tool is arranged in the heating chamber to clamp the coal block, and only part or all of the bottom surface of the coal block is exposed outside the coal block clamping tool; The suspension tool passes through the furnace body, and the bottom end of the suspension tool extends into the heating chamber and is connected to the coal block clamping tool; The online thermal balance is arranged outside the heating furnace, and the online thermal balance is connected to the top of the suspension tool; The heating furnace is provided with a heating element, which is arranged below the coal block holding tool; the top wall and side walls of the coal block holding tool are made of insulating material so that only the bottom surface of the coal block can be heated.

2. The test device for simulating thermal spalling of lump coal under underground coal gasification conditions according to claim 1, characterized in that: The test device comprises a temperature measuring element, which is used to measure the temperature of the heating chamber.

3. The test device for thermal spalling of lump coal under simulated underground coal gasification conditions according to claim 1, characterized in that: An observation window is provided on the side of the furnace body for observing the peeling and cracking of the coal blocks.

4. The test device for thermal spalling of lump coal under simulated underground coal gasification conditions according to claim 1, characterized in that: The heating element is a heating plate with silicon carbon rods, and the heating plate is arranged on the bottom surface of the heating chamber.

5. The test device for thermal spalling of lump coal under simulated underground coal gasification conditions according to claim 1, characterized in that: The coal block clamping tool includes a top wall, side walls and a bottom wall. The side wall surrounds the side of the coal block. The top and bottom ends of the side wall are respectively connected to the top wall and the bottom wall. The bottom wall is provided with a through hole to expose a portion of the bottom surface of the coal block.

6. The test device for thermal spalling of lump coal under simulated underground coal gasification conditions according to claim 1 or 5, characterized in that: The angle deviation between the bottom surface of the coal block and the bedding plane of the coal block does not exceed 10°.

7. The test device for thermal spalling of lump coal under simulated underground coal gasification conditions according to claim 1, characterized in that: A fixed bracket is provided on the top of the furnace body, and the online thermobalance is installed on the fixed bracket.

8. The test device for simulating thermal spalling of lump coal under underground coal gasification conditions according to claim 1, characterized in that: There is a gap between the suspension tool and the furnace body through-hole for the suspension tool to pass through, and the gap is greater than 1 mm and less than 3 mm.

9. A test system for simulating thermal spalling of lump coal under underground coal gasification conditions, characterized in that: The test system comprises a gasifying agent supply mechanism, a gas analyzer, and a test device according to any one of claims 1 to 8; The gasifying agent supply mechanism is connected to the gasifying agent inlet of the heating furnace to output the gasifying agent to the heating chamber of the heating furnace; The gas inlet of the gas analyzer is connected to the synthesis gas outlet of the heating furnace.

10. The test device for simulating thermal spalling of lump coal under underground coal gasification conditions according to claim 9, characterized in that: The gasifying agent supply mechanism includes a nitrogen supply device, a carbon dioxide supply device, an oxygen supply device and a water supply device, and the nitrogen supply device, the carbon dioxide supply device, the oxygen supply device and the water supply device are respectively used to selectively output corresponding gas or water to the heating chamber.

11. The test system for simulating thermal spalling of lump coal under underground coal gasification conditions according to claim 9, characterized in that: The test system includes a synthesis gas filter device and a coal tar purification device. The inlet of the synthesis gas filter device is connected to the synthesis gas outlet of the heating furnace. The outlet of the synthesis gas filter device, the coal tar purification device and the gas inlet of the gas analyzer are connected in sequence.

12. A test method for a test device for simulating thermal spalling of lump coal under underground coal gasification conditions as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Load the coal block into the coal block holding tool, connect the coal block holding tool to the online thermobalance through the hanging tool, close the door of the heating furnace, and perform an airtightness test on the heating furnace; After the airtightness test is passed, the gasifying agent supply mechanism outputs the gasifying agent required for the UCG reaction into the heating chamber; The heating element is started until the temperature of the heating chamber of the heating furnace reaches the set temperature. During this process, the mass of the coal block is monitored in real time by an online thermal balance, and a curve of the weight loss rate of the coal block changing with time is drawn and displayed. The thermal spalling characteristic parameters of the coal type to which the coal block belongs are obtained by analyzing the curve.

13. The test method according to claim 12, characterized in that the step of analyzing the curve to obtain the thermal spalling characteristic parameters comprises: The moment when the weight loss rate exceeds the set threshold is taken as the thermal spalling moment, and all thermal spalling moments and the weight loss rate at each thermal spalling moment are recorded as the thermal spalling characteristic parameters of the coal type to which the coal block belongs.

14. The test method according to claim 12, characterized in that the heating element is heated at a constant heating rate.

15. The test method according to claim 12, characterized in that the airtightness test comprises the following steps: The heating chamber of the heating furnace is purged with inert gas, and the oxygen concentration in the heating chamber is monitored by a gas analyzer until the oxygen concentration is lower than a predetermined value, confirming that the airtightness test has passed.

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