Method and device for testing competitive adsorption heat effect of CH4 gas in CO2 coal seam

Abstract

The invention discloses a CO2 coal seam CH4 gas competitive adsorption heat effect testing method and device, and belongs to the field of coal mines. The method comprises the following steps: loading a dry coal sample into a non-contact temperature measurement coal sample tank, and measuring the free space volume V0 in the non-contact temperature measurement coal sample tank; different environment temperatures and competitive adsorption pressures are set, the first step is repeated for multiple times, multiple first data sets are obtained, a relation curve of eta and delta T is obtained, and each first data set comprises the competitive adsorption replacement ratio eta of CO2 and CH4 gas and the heat effect delta T of the competitive adsorption equilibrium coal sample. The method has no influence on the replacement effect during testing, enables the measurement result to be accurate, can obtain the gas competitive adsorption and gas reciprocal diffusion rules in the process of replacing the CH4 in the coal seam by the CO2, can deeply analyze the driving mechanism and the action efficiency of the CH4 in the coal seam by the CO2 from the perspective of energy migration, and can improve the detection accuracy. And a theoretical support is provided for realizing reasonable optimization and efficiency maximization of key control parameters.

Description

Technical Field

[0001] The present application relates to the field of coal mine technology, and in particular to a method and device for testing the thermal effect of competitive adsorption of CH4 gas in a CO2 coal seam. Background Art

[0002] Mine gas (coalbed methane) is a combination of "hazard gas", "greenhouse gas" and "energy gas". It is not only the primary source of disasters threatening coal mine production safety, but also the main source of greenhouse effect. It is also a clean and high-quality unconventional natural gas resource. Efficient development of coalbed methane is very beneficial to increasing energy reserves, and it can also eliminate coal mine gas outbursts and reduce gas accidents.

[0003] Gas extraction is a fundamental measure for mine gas control and coalbed methane development. However, the naturally generated pressure gradient between underground coal seam pressure and atmospheric pressure can only recover 20% to 60% of CH4. This is mainly because the adsorption potential well on the coal surface is non-uniform. The smaller the adsorption amount, the deeper the potential well depth of the adsorbed CH4 molecules occupying the adsorption site, and the weaker the sensitivity of its adsorption state to the adsorption pressure. In order to improve the CH4 recovery rate of coal seams, gas enhanced desorption technologies such as heat injection, CO2 injection (liquid / gas / supercritical state), N2 injection, sound waves, and shock waves have developed rapidly. The common characteristics of the above technologies are that "gas desorption depends on the disturbance of the original coal seam balance and requires energy supply."

[0004] Among them, the ability of coal to absorb CO2 is greater than that of CH4. The technology of replacing coal seam CH4 with CO2 has the effect of improving coal seam gas recovery rate, realizing CO2 geological storage, and promoting the "dual carbon" goal, and has been widely used. How to maximize the replacement efficiency (replacement ratio) is the focus of the engineering application of CO2 replacement of coal seam CH4 technology. However, the actual working conditions have certain limitations due to the actual site and other restrictions. Therefore, the replacement ratio is studied through experiments, and the research results provide a theoretical basis for practical application.

[0005] During the process of CO2 replacing CH4 in coal seams, CO2 diffuses into the coal matrix and is adsorbed by the coal body, releasing heat, reducing the internal energy of CO2 and increasing the temperature of the coal body. The adsorbed CH4 absorbs the heat of the coal body and transforms into a free state, diffuses out of the coal matrix, and the internal energy of CH4 increases, while the temperature of the coal body decreases. Therefore, the replacement process is accompanied by the migration of energy within the system, that is, the entropy and enthalpy of the system change, which is macroscopically manifested as changes in the temperature of the coal body (thermal effect) and the reciprocal diffusion of gases, the size of which determines the final effect of the replacement, that is, the replacement ratio. The existing test method is affected by the pressure gradient, and the replacement effect is disturbed. When testing the competitive adsorption thermal effect of CO2 replacing CH4 in coal seams, it affects the replacement effect, making the measurement results inaccurate. In addition, most of the existing testing methods are explained from the aspects of CO2 multi-layer adsorption and CO2 preferential adsorption on vacant adsorption sites in coal bodies. The driving mechanism and effectiveness of CO2 replacement of coal seam CH4 have not been deeply analyzed from the perspective of energy migration, and the corresponding relationship between the two has not been quantified to provide theoretical support for the reasonable optimization of key control parameters and the maximization of replacement efficiency, which seriously restricts the engineering application and promotion of CO2 replacement of coal seam CH4 technology. Summary of the invention

[0006] The embodiments of the present application provide a method and device for testing the thermal effect of competitive adsorption of CH4 gas by CO2 in coal seams, which can solve the problems that the existing testing method is affected by the pressure gradient, the displacement effect is disturbed, the displacement effect is affected when testing the thermal effect of competitive adsorption of CH4 gas by CO2 in coal seams, resulting in inaccurate measurement results, and the driving mechanism and effectiveness of CO2 displacement of CH4 in coal seams are not deeply analyzed from the perspective of energy migration.

[0007] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0008] In a first aspect, an embodiment of the present invention provides a method for testing the thermal effect of competitive adsorption of CH4 gas in a CO2 coal seam, comprising:

[0009] A dry coal sample is placed in a non-contact temperature measuring coal sample tank, and a free space volume V0 in the non-contact temperature measuring coal sample tank is measured;

[0010] Set different ambient temperatures, CO2 and CH4 reciprocal diffusion and competitive adsorption to achieve the second equilibrium state pressure Repeat the first step multiple times to obtain multiple groups of first data groups to obtain η and ΔT relationship curves, each group of the first data group includes the CO2 and CH4 gas competitive adsorption replacement ratio η and the competitive adsorption equilibrium coal sample thermal effect ΔT;

[0011] Wherein, the first step comprises:

[0012] Obtain the initial amount of CH4 gas in the reference tank The non-contact temperature measuring coal sample tank is filled with CH4 gas through the reference tank to make the CH4 gas adsorb the dry coal sample, and the temperature change law of the dry coal sample during the adsorption process is monitored in real time until the adsorption reaches the first equilibrium state to obtain the first equilibrium temperature. First balance pressure Amount of CH4 gas adsorbed by dry coal sample

[0013] The reference tank 2 is slowly filled with CO2 gas through the high-pressure buffer tank 2, and the pressure in the reference tank 2 is consistent with the pressure of the non-contact temperature measurement coal sample tank in the first equilibrium state. When the CO2 gas is stopped, the amount of CO2 gas in the reference tank 2 is obtained. And calculate the amount of CH4 gas in the non-contact temperature measuring coal sample tank

[0014] The non-contact temperature measuring coal sample tank and the reference tank 2 are connected to allow CO2 and CH4 to diffuse and competitively adsorb each other, and the real-time temperature T of the dry coal sample, the pressure of the non-contact temperature measuring coal sample tank and the pressure of the reference tank 2 are monitored in real time until a second equilibrium state is reached, and a second equilibrium temperature under the second equilibrium state is obtained. Second balance pressure CO2 concentration CH4 concentration Competitive adsorption equilibrium Coal sample thermal effect

[0015] The CH4 gas partial pressure is obtained by the first formula and CO2 gas partial pressure Among them, the first formula is:

[0016]

[0017] The amount of CH4 gas in the reference tank 2 and the non-contact temperature measurement coal sample tank is obtained by the second formula and the amount of CO2 gas Wherein, the second formula is:

[0018]

[0019] Among them, V r is the volume of reference tank 1, The second equilibrium pressure The CH4 gas compressibility factor, R gas constant, The second equilibrium pressure The CO2 gas compression factor is:

[0020] Calculation of CH4 desorption CO2 adsorption

[0021] Calculation of the competitive adsorption replacement ratio of CO2 and CH4 gases

[0022] In combination with the first aspect, in a possible implementation, measuring the free space volume V0 in the non-contact temperature measuring coal sample tank includes:

[0023] Repeat the second step multiple times to obtain multiple second data groups, each of which includes the first initial temperature T1 of the reference tank 1; the first initial pressure value P1 in the reference tank 1; the second initial temperature T2 of the non-contact temperature measuring coal sample tank; the second initial pressure P2 in the non-contact temperature measuring coal sample tank; the temperature T2 after the rare gas and the dry coal sample are in adsorption equilibrium; pin ; Pressure P after adsorption equilibrium between rare gas and dry coal sample pin ;

[0024] According to the third formula and the plurality of the second data groups, a plurality of first equations are obtained, and the plurality of the first equations are solved simultaneously to obtain the free space volume V0 in the non-contact temperature measurement coal sample tank, wherein the third formula is:

[0025]

[0026] Wherein, V0 is the free space volume in the non-contact temperature measurement coal sample tank; V r is the volume of the reference tank 1; Y is the volume ratio; Z1 is the rare gas compression factor at the first initial pressure value P1 in the reference tank 1; Z pin is the pressure P after the adsorption equilibrium between the rare gas and the dry coal sample pin Z2 is the rare gas compression factor under the second initial pressure P2 in the contact temperature measurement coal sample tank;

[0027] Wherein, the second step comprises:

[0028] The high-pressure buffer tank 1, the reference tank 1 and the non-contact temperature measuring coal sample tank are evacuated;

[0029] The reference tank is set to a first initial temperature T1 and the non-contact temperature measuring coal sample tank is set to a second initial temperature T2 by a constant temperature water bath;

[0030] Filling the high-pressure buffer tank 1 with rare gas through a rare gas tank until the pressure in the high-pressure buffer tank 1 reaches a first preset pressure, and then stopping the input of rare gas;

[0031] When the pressure in the inner cavity of the high-pressure buffer tank 1 is stable, the rare gas is slowly filled into the reference tank 1 through the high-pressure buffer tank 1. When the pressure in the reference tank 1 reaches the first initial pressure P1, the input of the rare gas is stopped, and the pressure in the non-contact temperature measurement coal sample tank is measured to be the second initial pressure P2;

[0032] The reference tank 1 and the non-contact temperature measuring coal sample tank are connected until the pressure in the reference tank 1 and the pressure in the non-contact temperature measuring coal sample tank are stable and equal, and then balanced for 6h to 8h to obtain the pressure P after the adsorption equilibrium between the rare gas and the dry coal sample. pin , the temperature after the adsorption equilibrium between the rare gas and the dry coal sample is T pin .

[0033] In combination with the first aspect, in a possible implementation, the amount of the initial substance of CH4 gas in the reference tank is obtained. The non-contact temperature measuring coal sample tank is filled with CH4 gas through the reference tank to make the CH4 gas adsorb the dry coal sample, and the temperature change law of the dry coal sample during the adsorption process is monitored in real time until the adsorption reaches the first equilibrium state to obtain the first equilibrium temperature. First balance pressure Amount of CH4 gas adsorbed by dry coal sample include:

[0034] Discharging the rare gas in the high-pressure buffer tank 1, the reference tank 1 and the non-contact temperature measurement coal sample tank;

[0035] The high-pressure buffer tank 1, the reference tank 1 and the non-contact temperature measurement coal sample tank are evacuated;

[0036] The reference tank is brought to a third initial temperature by a constant temperature water bath.

[0037] Filling the high-pressure buffer tank 1 with CH4 gas through a CH4 gas tank until the pressure in the high-pressure buffer tank 1 reaches a second preset pressure, and then stopping the input of CH4 gas;

[0038] When the pressure in the inner cavity of the high-pressure buffer tank 1 is stable, the CH4 gas is slowly filled into the reference tank 1 through the high-pressure buffer tank 1, and the reference tank 1 is at a third initial pressure. When , stop inputting CH4 gas;

[0039] The initial amount of CH4 gas in the reference tank 1 is calculated by the fourth formula: The fourth formula is:

[0040]

[0041] in, V is the third initial pressure of the reference tank 1; r is the volume of the reference tank 1; The third initial pressure The CH4 gas compression factor is shown below; R is the gas constant; is the third initial temperature of the reference tank 1;

[0042] The reference tank 1 and the non-contact temperature measuring coal sample tank are connected, and CH4 gas is filled into the non-contact temperature measuring coal sample tank through the reference tank 1 so that the CH4 gas adsorbs the dry coal sample, and the temperature change law of the dry coal sample during the adsorption process is monitored in real time until the adsorption reaches a first equilibrium state to obtain a first equilibrium temperature. First balance pressure Amount of CH4 gas adsorbed by dry coal sample

[0043] The amount of CH4 gas in the reference tank 1 and the non-contact temperature measurement coal sample tank is calculated by the fifth formula The fifth formula is:

[0044]

[0045] In the formula, The first equilibrium pressure The compression factor of CH4 gas is:

[0046] Amount of CH4 gas adsorbed by dry coal sample

[0047] In combination with the first aspect, in a possible implementation, the method for testing the thermal effect of competitive adsorption of CH4 gas in a CO2 coal seam further includes:

[0048] Collect the exhaust gas.

[0049] In a second aspect, an embodiment of the present invention provides a CO2 coal seam CH4 gas competitive adsorption thermal effect test device, which is used to implement the above-mentioned CO2 coal seam CH4 gas competitive adsorption thermal effect test method, including: a CH4 gas tank, a rare gas tank, a high-pressure buffer tank one, a reference tank one, a non-contact temperature measurement coal sample tank, an infrared thermal imager, a data acquisition and storage mechanism, a reference tank two, a high-pressure buffer tank two, a CO2 gas tank, a constant temperature water bath, a vacuum mechanism, a pressure gauge one, a pressure gauge two, a valve one, a valve two, a valve three, a three-way one, a valve four, a valve five, a four-way one, a valve six, a four-way two, a valve seven, a four-way three, a valve eight, a three-way two, a valve nine, a valve ten, a valve eleven, a valve twelve, a pressure sensor one, a pressure sensor two, a pressure sensor three, a CO2 concentration sensor and a CH4 concentration sensor;

[0050] Connecting the CH4 gas tank to the high-pressure buffer tank 1 through a first pipeline, and setting the valve 1 on the first pipeline;

[0051] Connecting the rare gas tank to the first high-pressure buffer tank through a second pipeline, and arranging the second valve on the second pipeline;

[0052] The high-pressure buffer tank 1 is connected to the four-way 1 through a third pipeline, and the valve 3, the three-way 1, and the valve 5 are sequentially arranged on the third pipeline in a direction from the high-pressure buffer tank 1 to the four-way 1;

[0053] The pressure gauge 1 is arranged on the high-pressure buffer tank 1;

[0054] Connecting the three-way valve 1 and the vacuum pumping mechanism through a fourth pipeline, and arranging the valve 4 on the fourth pipeline;

[0055] Connect the four-way one with the four-way two through a fifth pipeline, and set the valve six on the fifth pipeline;

[0056] The reference tank 1 and the pressure sensor 1 are respectively connected to the four-way 1;

[0057] The non-contact temperature measuring coal sample tank and the second pressure sensor are respectively connected to the second four-way;

[0058] The four-way three and the high-pressure buffer tank two are connected through a sixth pipeline, and the valve eight, the three-way two and the valve ten are sequentially arranged on the sixth pipeline in a direction from the four-way three to the high-pressure buffer tank two;

[0059] The second pressure gauge is arranged on the second high-pressure buffer tank;

[0060] Connecting the CO2 gas tank and the second high-pressure buffer tank through a seventh pipeline, and setting the eleventh valve on the seventh pipeline;

[0061] Connect the four-way two and the four-way three through an eighth pipeline, and set the valve seven on the eighth pipeline;

[0062] The valve twelve is arranged on the output pipeline at the bottom of the high-pressure buffer tank one;

[0063] The non-contact temperature measurement coal sample tank comprises a tank body, a tank cover and an infrared light high permeability single crystal;

[0064] The can cover is arranged at the opening of the can body to close the can body, a mounting hole is arranged in the middle of the can cover, and the infrared light high permeability single crystal is arranged at the mounting hole;

[0065] The infrared thermal imager is arranged above the infrared light high permeability single crystal;

[0066] The reference tank 2 and the pressure sensor 3 are both connected to the four-way 3;

[0067] The CO2 concentration sensor is arranged on the non-contact temperature measurement coal sample tank, and the CH4 concentration sensor is arranged on the reference tank 2;

[0068] The pressure sensor 1, the pressure sensor 2, the pressure sensor 3, the CO2 concentration sensor, the CH4 concentration sensor, and the infrared thermal imager are all electrically connected to the data acquisition and storage mechanism;

[0069] The reference tank 1, the non-contact temperature measurement coal sample tank and the reference tank 2 are arranged in the constant temperature water bath.

[0070] In conjunction with the second aspect, in a possible implementation, the CO2 coal seam CH4 gas competitive adsorption thermal effect test device further includes a valve nine and an exhaust gas collection bag;

[0071] The tail gas collection bag and the tee two are connected via a ninth pipeline, and the valve nine is arranged on the ninth pipeline.

[0072] In combination with the second aspect, in a possible implementation, the reference tank one and the reference tank two, the valve five and the valve eight, the four-way one and the four-way three are symmetrically distributed with the central axis of the non-contact temperature measurement coal sample tank as the axis of symmetry.

[0073] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0074] The method for testing the heat effect of competitive adsorption of CH4 gas by CO2 in coal seams provided by the embodiment of the present invention can avoid the influence of pressure gradient on the replacement effect by setting reference tank 1 and reference tank 2, and the replacement effect is not disturbed, so that the replacement effect is not affected when testing the heat effect of competitive adsorption of CH4 gas by CO2 in coal seams, so that the measurement results are accurate, and the laws of competitive adsorption of gas and mutual counter-diffusion of gas in the process of CH4 replacement in coal seams can be obtained. By real-time monitoring of the temperature change law of dry coal samples during the adsorption process of CH4 gas adsorption on dry coal samples, real-time monitoring of the temperature change law of CO2 and CH4 mutual counter-diffusion and competitive adsorption of dry coal samples, the pressure of the non-contact temperature measurement coal sample tank and the pressure change law of reference tank 2, it is possible to conduct an in-depth analysis of the driving mechanism and action efficiency of CH4 replacement in coal seams by CO2 from the perspective of energy migration, and provide theoretical support for the reasonable optimization of key control parameters and the realization of maximum efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments of the present invention or the description of the prior art will be briefly introduced below. 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 creative work.

[0076] Figure 1 A schematic diagram of the structure of a device for testing the thermal effect of competitive adsorption of CH4 gas on CO2 coal seams provided in an embodiment of the present application;

[0077] Figure 2 A cross-sectional view of a non-contact temperature measuring coal sample tank provided in an embodiment of the present application;

[0078] Figure 3 A top view of the non-contact temperature measurement coal sample tank provided in an embodiment of the present application.

[0079] Icons: 1-CH4 gas tank, 2-rare gas tank, 3-high pressure buffer tank 1, 4-reference tank 1, 5-non-contact temperature measurement coal sample tank, 51-tank body, 52-tank cover, 53-infrared light high permeability single crystal, 54-inlet and outlet pipes, 55-fixing parts, 56-first set of buckles, 57-second set of buckles, 58-O-ring 1, 59-O-ring 2, 6-infrared thermal imager, 7-data acquisition storage mechanism, 71-data acquisition instrument, 72-computer, 8-reference tank 2, 9-high pressure buffer tank 2, 10-CO2 gas tank, 11-constant temperature water bath, 12-vacuum extraction mechanism, 13-pressure Force gauge 1, 14-pressure gauge 2, 15-valve 1, 16-valve 2, 17-valve 3, 18-three-way 1, 19-valve 4, 20-valve 5, 21-four-way 1, 22-valve 6, 23-four-way 2, 24-valve 7, 25-four-way 3, 26-valve 8, 27-three-way 2, 28-valve 9, 29-valve 10, 30-valve 11, 31-valve 12, 32-valve 13, 33-pressure sensor 1, 34-pressure sensor 2, 35-pressure sensor 3, 36-CO2 concentration sensor, 37-CH4 concentration sensor, 38-dry coal sample. DETAILED DESCRIPTION

[0080] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0082] In practice, Figure 1 As shown, the CO2 coal seam CH4 gas competitive adsorption thermal effect testing device of the embodiment of the present invention connects the CH4 gas tank 1 with the high-pressure buffer tank 3 through a first pipeline, and a valve 15 is arranged on the first pipeline; connects the rare gas gas tank 2 with the high-pressure buffer tank 3 through a second pipeline, and a valve 2 16 is arranged on the second pipeline; connects the high-pressure buffer tank 3 with the four-way 21 through a third pipeline, and sequentially arranges valves 3 17, tee 18, and valve 5 20 on the third pipeline from the high-pressure buffer tank 3 to the four-way 21; arranges a pressure gauge 13 on the high-pressure buffer tank 3; connects the three-way 18 and the vacuum pumping mechanism 12 (the vacuum pumping mechanism 12 can adopt a vacuum pump) through a fourth pipeline, and arranges valve 4 19 on the fourth pipeline; connects the four-way 21 and the four-way 23 through a fifth pipeline, and arranges valve 6 22 on the fifth pipeline; the reference tank 4 and the pressure sensor 33 are respectively connected to the four-way 21.

[0083] The non-contact temperature measuring coal sample tank 5 and the pressure sensor 2 34 are respectively connected to the four-way 23 .

[0084] The four-way three 25 and the high-pressure buffer tank two 9 are connected through the sixth pipeline, and valve eight 26, three-way two 27 and valve ten 29 are sequentially arranged on the sixth pipeline in the direction from the four-way three 25 to the high-pressure buffer tank two 9; a pressure gauge two 14 is arranged on the high-pressure buffer tank two 9; the CO2 gas tank 10 and the high-pressure buffer tank two 9 are connected through the seventh pipeline, and a valve ten 30 is arranged on the seventh pipeline; the four-way two 23 and the four-way three 25 are connected through the eighth pipeline, and a valve seven 24 is arranged on the eighth pipeline; a valve twelve 31 is arranged on the output pipeline at the bottom of the high-pressure buffer tank one 3; the non-contact temperature measurement coal sample tank 5 includes a tank body 51, a tank cover 52 and an infrared light high permeability single crystal 53; the tank cover 52 is arranged at the opening of the tank body 51 The tank body 51 is closed, and a mounting hole is set in the middle of the tank cover 52, and an infrared light high permeability single crystal 53 is set at the mounting hole; the infrared thermal imager 6 is set above the infrared light high permeability single crystal 53; the reference tank 2 8 and the pressure sensor 3 35 are both connected to the four-way 3 25; the non-contact temperature measurement coal sample tank 5 is provided with a CO2 concentration sensor 36, and the reference tank 2 8 is provided with a CH4 concentration sensor 37; the pressure sensor 1 33, the pressure sensor 2 34, the pressure sensor 3 35, the CO2 concentration sensor 36, the CH4 concentration sensor 37, and the infrared thermal imager 6 are all electrically connected to the data acquisition storage mechanism 7; the reference tank 1 4, the non-contact temperature measurement coal sample tank 5 and the reference tank 2 8 are set in a constant temperature water bath 11. A valve 13 32 is set on the output pipeline at the bottom of the high-pressure buffer tank 2 9.

[0085] The embodiment of the present invention provides a method for testing the thermal effect of competitive adsorption of CH4 gas in a CO2 coal seam, comprising:

[0086] Step 1: Place the dry coal sample 38 in the non-contact temperature measuring coal sample tank 5 (weigh 300g of the dry coal sample 38 and place it in the non-contact temperature measuring coal sample tank 5), according to Figure 1 Connect the CO2 coal seam CH4 gas competitive adsorption thermal effect test device, check the air tightness and integrity of the device, and measure the free space volume V0 in the non-contact temperature measurement coal sample tank 5.

[0087] Among them, the preparation method of dry coal sample 38 is: collect large pieces of coal samples underground, seal them tightly and transport them to the laboratory, break the surface oxide layer, manually crush them into 60-80 mesh, put them into a vacuum drying oven and dry them at a constant temperature of 40°C for 24 hours to obtain dry coal sample 38, and put the dry coal sample 38 into a sealing tape for standby use.

[0088] The free space volume V0 in the non-contact temperature measuring coal sample tank 5 is measured, including:

[0089] Step 11: Repeat the second step multiple times to obtain multiple second data groups, that is, obtain multiple sets of gas state equations about the pressure of the non-contact temperature measuring coal sample tank 5, each set of the second data group includes the first initial temperature T1 of the reference tank 4, in units of K; the first initial pressure value P1 in the reference tank 4, in units of MPa; the second initial temperature T2 of the non-contact temperature measuring coal sample tank 5, in units of K; the second initial pressure P2 in the non-contact temperature measuring coal sample tank 5, in units of MPa; the temperature T after the rare gas and the dry coal sample 38 are adsorbed in equilibrium pin , unit is K; the pressure P after the adsorption equilibrium between the rare gas and the dry coal sample 38 pin , unit is MPa. The rare gas may be He gas.

[0090] Step 12: A plurality of first equations are obtained according to the third formula and a plurality of second data groups, and the plurality of first equations are solved simultaneously to obtain the free space volume V0 in the non-contact temperature measurement coal sample tank 5, wherein the third formula is:

[0091]

[0092] Where V0 is the free space volume in the non-contact temperature measurement coal sample tank 5, in cm 3 ; V r is the volume of reference tank 4, in cm 3 ; Y is the volume ratio, dimensionless; Z1 is the rare gas compression factor at the first initial pressure value P1 in the reference tank 4, dimensionless; Z pin is the pressure P after the adsorption equilibrium between the rare gas and the dry coal sample 38 pin Z2 is the rare gas compression factor at the second initial pressure P2 in the contact temperature measurement coal sample tank, which is dimensionless.

[0093] The second step includes:

[0094] Step 111: Open valve three 17, valve four 19, valve five 20, valve six 22, open the vacuum pumping mechanism 12, and vacuum the high-pressure buffer tank one 3, reference tank one 4, and non-contact temperature measurement coal sample tank 5 (due to the entire installation connection of the device, when vacuuming the high-pressure buffer tank one 3, reference tank one 4, and non-contact temperature measurement coal sample tank 5, open valve three 17, valve four 19, valve five 20, valve six 22, valve seven 24, valve eight 26, and valve ten 29, open the vacuum pumping mechanism 12, and vacuum the high-pressure buffer tank one 3, reference tank one 4, non-contact temperature measurement coal sample tank 5, reference tank two 8, high-pressure buffer tank two 9, and pipelines at the same time). Maintain a negative pressure of 0.9 MPa, and continue vacuuming for 30 minutes, then close valve three 17, valve four 19, valve five 20, valve six 22 (close valve eight 26 and valve ten 29 at the same time). At this time, the pressure sensor 1 33 measures the pressure in the reference tank 4, and the pressure sensor 2 34 measures the pressure in the non-contact measurement coal sample tank, both of which are P0.

[0095] Step 112: adjust the constant temperature water bath 11 to the first experimental temperature T0, and place the reference tank 4 and the non-contact temperature measurement coal sample tank 5 in the constant temperature water bath 11. After stabilization, use the constant temperature water bath to adjust the reference tank 4 to the first initial temperature T1, and adjust the non-contact temperature measurement coal sample tank 5 to the second initial temperature T2, and T1=T2.

[0096] Step 113: Open the valve 16, and fill the high-pressure buffer tank 3 with rare gas through the rare gas tank 2 until the pressure in the high-pressure buffer tank 3 reaches the first preset pressure, that is, when the pressure gauge 13 shows that the pressure in the high-pressure buffer tank 3 reaches the first preset pressure (> the experimental pressure), close the valve 16, that is, stop inputting rare gas into the high-pressure buffer tank 3. Thus, a rare gas source with a constant pressure is obtained.

[0097] Step 114: When the pressure in the inner cavity of the high-pressure buffer tank 3 is stable, first open valve five 20, and then slowly open valve three 17, and slowly fill the reference tank 4 with rare gas through the high-pressure buffer tank 3. When the pressure sensor 33 measures the pressure in the reference tank 4 to the first initial pressure P1, close valve five 20 and valve three 17, stop inputting rare gas, and the pressure sensor two 34 measures the pressure in the non-contact temperature measurement coal sample tank 5 to be the second initial pressure P2.

[0098] Step 115: Slowly open valve 6 22, connect the reference tank 1 4 and the non-contact temperature measuring coal sample tank 5 to the pressure sensor 1 33. When the pressure in the reference tank 1 4 and the pressure in the non-contact temperature measuring coal sample tank 5 measured by the pressure sensor 2 34 are stable and equal, balance for 6h to 8h. At this time, the rare gas and the dry coal sample 38 placed in the non-contact temperature measuring coal sample tank 5 are in adsorption equilibrium. When the pressures in the reference tank 1 4 and the non-contact temperature measuring coal sample tank 5 are equal, the pressure P after the rare gas and the dry coal sample 38 are in adsorption equilibrium is obtained. pin , the temperature T after the adsorption equilibrium between the rare gas and the dry coal sample 38 pin , there exists T pin =T1=T2.

[0099] Step 2: Setting different ambient temperatures (i.e., the second experimental temperature to which the constant temperature water bath 11 is adjusted during the CH4 gas adsorption drying process of the coal sample 38) ), the pressure at which CO2 and CH4 mutually diffuse and compete for adsorption to reach the second equilibrium state The first step is repeated multiple times to obtain multiple groups of first data groups to obtain η and ΔT relationship curves, each group of first data groups includes the CO2 and CH4 gas competitive adsorption replacement ratio η and the competitive adsorption equilibrium coal sample thermal effect ΔT.

[0100] The first step includes:

[0101] Step 21: Obtain the initial amount of CH4 gas in the reference tank 4 The non-contact temperature measurement coal sample tank 5 is filled with CH4 gas through the reference tank 4 so that the CH4 gas adsorbs the dry coal sample 38 until the adsorption reaches a first equilibrium state and a first equilibrium temperature is obtained. First balance pressure Amount of CH4 gas adsorbed by dry coal sample 38

[0102] Wherein, step 21 (i.e., CH4 isothermal adsorption process) comprises:

[0103] Step 211: Slowly open valve three 17, valve five 20 and valve twelve 31 (valve six 22 is in the open state in the previous step) to discharge the rare gas in high pressure buffer tank one 3, reference tank one 4 and non-contact temperature measurement coal sample tank 5. Close valve twelve 31.

[0104] Step 212: open valve four 19 (valve three 17, valve five 20 and valve six 22 are in the open state in the previous step, valve seven 24, valve eight 26, three-way valve two 27 and valve ten 29 are in the closed state in the previous step), open the vacuum mechanism 12, vacuum the high-pressure buffer tank 3, reference tank 4 and non-contact temperature measurement coal sample tank 5, maintain a negative pressure of 0.9 MPa, continue vacuuming for 30 minutes, and close valve three 17, valve four 19, valve five 20 and valve six 22.

[0105] Step 213: Adjust the constant temperature water bath 11 to the second experimental temperature The reference tank 4 and the non-contact temperature measurement coal sample tank 5 are placed in a constant temperature water bath 11. After stabilization, the reference tank 4 is brought to a third initial temperature by a constant temperature water bath. Make the non-contact temperature measurement coal sample tank 5 to the fourth initial temperature exist

[0106] Step 214: Open valve 15 to charge CH4 gas into high-pressure buffer tank 3 through CH4 gas tank 1, wait until pressure gauge 13 shows that the pressure in high-pressure buffer tank 3 reaches the second preset pressure, close valve 15, stop inputting CH4 gas into high-pressure buffer tank 3, and thus obtain a CH4 gas source with a constant pressure.

[0107] Step 215: When the pressure in the high-pressure buffer tank 3 is stable, first open the valve 5 20, then slowly open the valve 3 17, and slowly fill the reference tank 4 with CH4 gas through the high-pressure buffer tank 3, and wait until the pressure sensor 33 measures that the reference tank 4 is at the third initial pressure. When the valve 5 20 and the valve 3 17 are closed, the input of CH4 gas is stopped, and the pressure sensor 2 34 measures the pressure in the non-contact temperature measuring coal sample tank 5 to be the fourth initial pressure value.

[0108] Step 216: Calculate the initial amount of CH4 gas in the reference tank 4 using the fourth formula The unit is mol, and the fourth formula is:

[0109]

[0110] in, V is the third initial pressure of the reference tank 4, in MPa; r is the volume of reference tank 4, in cm 3 ; The third initial pressure The CH4 gas compressibility factor is dimensionless; R is the gas constant, which is 8.314 J / (mol·K); is the third initial temperature of the reference tank 4, in K.

[0111] Step 217: Slowly open valve 6 22 to connect reference tank 1 4 and non-contact temperature measuring coal sample tank 5, fill CH4 gas into non-contact temperature measuring coal sample tank 5 through reference tank 1 4 to make CH4 gas adsorb dry coal sample 38, and monitor the temperature change law of dry coal sample 38 in real time during adsorption process through infrared thermal imager 6 until the first equilibrium state is reached and the first equilibrium temperature is obtained. First balance pressure Amount of CH4 gas adsorbed by dry coal sample 38 That is, when the pressure in the reference tank 4 measured by the pressure sensor 33 and the pressure in the non-contact temperature measurement coal sample tank 5 measured by the pressure sensor 2 34 are stable and equal, they are balanced for 6h to 8h. At this time, the reference tank 4 and the non-contact temperature measurement coal sample tank 5 reach equilibrium, and the first equilibrium pressure is The first equilibrium temperature is exist

[0112] Step 218: Calculate the amount of CH4 gas in the reference tank 4 and the non-contact temperature measurement coal sample tank 5 by the fifth formula The unit is mol, and the fifth formula is:

[0113]

[0114] Where V r is the volume of reference tank 4, in cm 3 ; V0 is the free space volume in the non-contact temperature measurement coal sample tank 5, in cm 3 ; The first equilibrium pressure is the CH4 gas compressibility factor, dimensionless; R is the gas constant, whose value is 8.314 J / (mol·K).

[0115] Step 219: Amount of CH4 gas adsorbed by the dry coal sample 38

[0116] Before step 22, it also includes vacuuming the reference tank 2 8 and the high-pressure buffer tank 2 9. Specifically, when vacuuming the high-pressure buffer tank 1 3, the reference tank 1 4 and the non-contact temperature measurement coal sample tank 5, open valve 3 17, valve 4 19, valve 5 20, valve 6 22, valve 7 24, valve 8 26 and valve 10 29, open the vacuuming mechanism 12, and vacuumize the high-pressure buffer tank 1 3, the reference tank 1 4, the non-contact temperature measurement coal sample tank 5, the reference tank 2 8 and the high-pressure buffer tank 2 9 at the same time, maintain a negative pressure of 0.9 MPa, and continue vacuuming for 30 minutes. Then close valve 3 17, valve 4 19, valve 5 20, valve 6 22, valve 7 24, valve 8 26 and valve 10 29.

[0117] Step 22: After the aforementioned step 21, close the valve 6 22, slowly open the valve 11 30, and fill the high-pressure buffer tank 2 9 with CO2 gas through the CO2 gas cylinder 10 until the pressure gauge 2 14 shows that the pressure in the high-pressure buffer tank 2 9 reaches the third preset pressure (> the experimental pressure), and then close the valve 11 30, that is, stop inputting CO2 gas into the high-pressure buffer tank 2 9. Thus, a CO2 gas source with a constant pressure is obtained.

[0118] When the pressure in the high-pressure buffer tank 29 is stable, first open the valve 8 26, then slowly open the valve 10 29, and slowly fill the reference tank 28 with CO2 gas through the high-pressure buffer tank 29. When the pressure sensor 3 35 measures the pressure in the reference tank 28 to the first equilibrium state, the pressure of the non-contact temperature measurement coal sample tank 5 is consistent. When the pressure in the non-contact temperature measuring coal sample tank 5 measured by the pressure sensor 2 34 is equal to the pressure in the reference tank 3 measured by the pressure sensor 3 35, the amount of CO2 gas in the reference tank 2 8 is obtained. (Where, The first equilibrium pressure The CO2 gas compression factor is dimensionless), and the amount of CH4 gas in the non-contact temperature measurement coal sample tank 5 is calculated.

[0119] Step 23: Open valve seven 24, connect the non-contact temperature measurement coal sample tank 5 and the reference tank two 8, so that the counter-diffusion and competitive adsorption of CO2 and CH4 continue for 6h to 8h, and use the infrared thermal imager 6 to monitor the real-time temperature T of the dry coal sample 38, the pressure sensor two 34 to monitor the pressure of the non-contact temperature measurement coal sample tank 5, and the pressure sensor three 35 to monitor the pressure change of the reference tank two 8 in real time, until the second equilibrium state is reached, and the second equilibrium temperature under the second equilibrium state is obtained. Second balance pressure The CO2 concentration sensor 36 obtains the CO2 concentration variation law in the non-contact temperature measurement coal sample tank 5 and the CO2 concentration in the second equilibrium state. The CH4 concentration variation law in the reference tank 8 and the CH4 concentration in the second equilibrium state are obtained by the CH4 concentration sensor 37. Competitive adsorption equilibrium Coal sample thermal effect The second equilibrium state is the state in which the pressure of the non-contact temperature measuring coal sample tank 5 measured by the pressure sensor 2 34 and the pressure of the reference tank 2 8 measured by the pressure sensor 3 35 display the same values, and the gas components of the non-contact temperature measuring coal sample tank 5 and the reference tank 2 8 are stable.

[0120] Step 24: Obtain the CH4 gas partial pressure using the first formula and CO2 gas partial pressure Among them, the first formula is:

[0121]

[0122] Step 25: Obtain the amount of CH4 gas in the reference tank 8 and the non-contact temperature measurement coal sample tank 5 by the second formula and the amount of CO2 gas Among them, the second formula is:

[0123]

[0124] Among them, V r is the volume of reference tank 4, in cm 3 ; V0 is the free space volume in the non-contact temperature measurement coal sample tank, in cm 3 ; The second equilibrium pressure The CH4 gas compressibility factor is dimensionless; R is the gas constant, which is 8.314 J / (mol·K); The second equilibrium pressure The CO2 gas compressibility factor is dimensionless.

[0125] Step 26: Calculate CH4 desorption CO2 adsorption

[0126]

[0127] Step 27: Calculate the competitive adsorption replacement ratio of CO2 and CH4 gases

[0128] Step 3: Collect the exhaust gas.

[0129] Slowly open valve eight 26, valve ten 29 and valve thirteen 32 to discharge CO2 in high pressure buffer tank two 9 and reference tank two 8. Then close valve thirteen 32.

[0130] The method for testing the heat effect of competitive adsorption of CH4 gas by CO2 in coal seams provided by the embodiment of the present invention can avoid the influence of pressure gradient on the replacement effect by setting reference tank 1 4 and reference tank 2 8, and the replacement effect is not disturbed, so that the replacement effect is not affected when the CO2 replaces the CH4 gas by competitive adsorption heat effect test, so that the measurement result is accurate, and the gas competitive adsorption and gas mutual diffusion law of the CO2 replacement of CH4 in the coal seams can be obtained. By real-time monitoring the temperature change law of the dry coal sample 38 during the adsorption process of the CH4 gas adsorbed dry coal sample 38, real-time monitoring the temperature change law of the CO2 and CH4 mutual diffusion and competitive adsorption dry coal sample 38, the pressure of the non-contact temperature measurement coal sample tank 5 and the pressure change law of the reference tank 2 8, the driving mechanism and action efficiency of the CO2 replacement of CH4 in the coal seams can be deeply analyzed from the perspective of energy migration, and theoretical support can be provided for the reasonable optimization of key control parameters and the realization of efficiency maximization.

[0131] Another embodiment of the present invention provides a CO2 coal seam CH4 gas competitive adsorption thermal effect test device, which is used to implement the above-mentioned CO2 coal seam CH4 gas competitive adsorption thermal effect test method, including: a CH4 gas tank 1, a rare gas tank 2, a high-pressure buffer tank 3, a reference tank 4, a non-contact temperature measurement coal sample tank 5, an infrared thermal imager 6, a data acquisition and storage mechanism 7, a reference tank 8, a high-pressure buffer tank 9, a CO2 gas tank 10, a constant temperature water bath 11, a vacuum pumping mechanism 12, a pressure Gauge one 13, pressure gauge two 14, valve one 15, valve two 16, valve three 17, three-way one 18, valve four 19, valve five 20, four-way one 21, valve six 22, four-way two 23, valve seven 24, four-way three 25, valve eight 26, three-way two 27, three-way two 27, valve ten 29, valve eleven 30, valve twelve 31, pressure sensor one 33, pressure sensor two 34, pressure sensor three 35, CO2 concentration sensor 36 and CH4 concentration sensor 37.

[0132] The CH4 gas tank 1 is connected to the high-pressure buffer tank 3 through the first pipeline, and a valve 15 is set on the first pipeline. The rare gas tank 2 is connected to the high-pressure buffer tank 3 through the second pipeline, and a valve 2 16 is set on the second pipeline. The high-pressure buffer tank 3 and the four-way 21 are connected through the third pipeline, and valves 3 17, tee 18, and valve 5 20 are sequentially set on the third pipeline from the high-pressure buffer tank 3 to the four-way 21. A pressure gauge 13 is set on the high-pressure buffer tank 3. The three-way 18 and the vacuum pumping mechanism 12 are connected through the fourth pipeline, and a valve 4 19 is set on the fourth pipeline.

[0133] The four-way 1 21 and the four-way 2 23 are connected through the fifth pipeline, and a valve 6 22 is set on the fifth pipeline. The reference tank 1 4 and the pressure sensor 1 33 are respectively connected to the four-way 1 21. The non-contact temperature measurement coal sample tank 5 and the pressure sensor 2 34 are respectively connected to the four-way 2 23.

[0134] The four-way three 25 and the high-pressure buffer tank two 9 are connected through the sixth pipeline, and valve eight 26, three-way two 27 and valve ten 29 are sequentially arranged on the sixth pipeline from the four-way three 25 to the high-pressure buffer tank two 9. A pressure gauge two 14 is arranged on the high-pressure buffer tank two 9. The CO2 gas tank 10 and the high-pressure buffer tank two 9 are connected through the seventh pipeline, and a valve eleven 30 is arranged on the seventh pipeline. The four-way two 23 and the four-way three 25 are connected through the eighth pipeline, and a valve seven 24 is arranged on the eighth pipeline. A valve twelve 31 is arranged on the output pipeline at the bottom of the high-pressure buffer tank one 3.

[0135] The non-contact temperature measurement coal sample tank 5 includes a tank body 51, a tank cover 52 and an infrared light high permeability single crystal 53. The tank cover 52 is arranged at the opening of the tank body 51 to close the tank body 51. The tank body 51 is made of stainless steel and is designed to be cylindrical. Its internal space is φ140mm×140mm and its wall thickness is 10mm. It can hold 250g~300g of 60-80 mesh coal samples. An inlet and outlet pipe 54 is arranged 20mm from the top of the tank body 51 to ensure that the inlet and outlet pipe 54 is located above the dry coal sample 38 to avoid disturbance of the dry coal sample 38 by gas in and out.

[0136] The middle of the tank cover 52 is provided with a mounting hole, and a single crystal 53 with high infrared permeability is arranged at the mounting hole to form a projection hole. The tank cover 52 is made of stainless steel and is designed to be cylindrical with a diameter of 200 mm × 10 mm. Figure 2 and Figure 3 As shown, the annular fixing member 55 clamps the infrared light high permeability single crystal 53, and then a plurality of first buckles 56 fix the fixing member 55 to the mounting hole of the tank cover 52 to achieve sealing. Then the tank cover 52 and the tank body 51 are fixed by the second buckle 57. An O-ring 1 58 is provided on the top surface of the tank body 51 and the bottom surface of the tank cover 52. An O-ring 2 59 is provided at the contact point between the infrared light high permeability single crystal 53 and the tank cover 52 to achieve sealing.

[0137] The infrared thermal imager 6 is arranged above the infrared light high permeability single crystal 53. The infrared thermal imager 6 monitors the temperature change of the dry coal sample 38 in real time through the infrared light high permeability single crystal. The infrared light high permeability single crystal is made of germanium single crystal, with a transmittance of up to 95%, and is designed to be circular φ120mm×10mm.

[0138] The reference tank 2 8 and the pressure sensor 3 35 are both connected to the four-way 3 25 .

[0139] A CO2 concentration sensor 36 is provided on the non-contact temperature measurement coal sample tank 5, and a CH4 concentration sensor 37 is provided on the reference tank 2 8. The pressure sensor 1 33, the pressure sensor 2 34, the pressure sensor 3 35, the CO2 concentration sensor 36, the CH4 concentration sensor 37, and the infrared thermal imager 6 are all electrically connected to the data acquisition storage mechanism 7 (the data acquisition storage mechanism 7 includes a data acquisition instrument 71 and a computer 72, which are electrically connected). The reference tank 1 4, the non-contact temperature measurement coal sample tank 5, and the reference tank 2 8 are arranged in a constant temperature water bath 11. By controlling the water temperature of the constant temperature water bath 11, a constant temperature environment is provided for the CO2 coal seam CH4 gas competitive adsorption thermal effect test device.

[0140] The pressure sensor 1 33 monitors the pressure of the reference tank 1 4 in real time, the pressure sensor 2 34 monitors the pressure of the non-contact temperature measurement coal sample tank 5 in real time, the infrared thermal imager 6 monitors the temperature of the dry coal sample 38 in the non-contact temperature measurement coal sample tank 5 in real time, the CO2 concentration sensor 36 monitors the CO2 concentration in the gas in the non-contact temperature measurement coal sample tank 5 in real time, the CH4 concentration sensor 37 monitors the CH4 concentration in the gas in the reference tank 2 8 in real time, and the pressure sensor 3 35 monitors the pressure of the reference tank 2 8 in real time. The data acquisition instrument 71 collects data from the pressure sensor 1 33, the pressure sensor 2 34, the infrared thermal imager 6, the CO2 concentration sensor 36, the CH4 concentration sensor 37 and the pressure sensor 3 35. The computer 72 analyzes and plots the data collected by the data acquisition instrument 71.

[0141] The working process and principle of the CO2 coal seam CH4 gas competitive adsorption thermal effect test device provided by the embodiment of the present invention are as described in the above method, and will not be repeated here. The CO2 coal seam CH4 gas competitive adsorption thermal effect test device provided by the embodiment of the present invention can avoid the influence of the pressure gradient on the replacement effect by setting the reference tank 1 4 and the reference tank 2 8, and the replacement effect is not disturbed, so that the CO2 replacement coal seam CH4 gas competitive adsorption thermal effect test has no effect on the replacement effect, so that the measurement result is accurate, and the gas competitive adsorption and gas mutual diffusion law of the CO2 replacement coal seam CH4 process can be obtained. By real-time monitoring the temperature change law of the dry coal sample 38 during the adsorption process of the CH4 gas adsorption dry coal sample 38, real-time monitoring of the CO2 and CH4 mutual diffusion and competitive adsorption of the dry coal sample 38, the pressure of the non-contact temperature measurement coal sample tank 5 and the pressure change law of the reference tank 2 8, the driving mechanism and action efficiency of the CO2 replacement coal seam CH4 can be deeply analyzed from the perspective of energy migration, and the theoretical support is provided for the reasonable optimization of key control parameters and the realization of efficiency maximization.

[0142] Furthermore, the CO2 coal seam CH4 gas competitive adsorption thermal effect test device also includes valve nine 28 and tail gas collection bag. The tail gas collection bag and three-way two 27 are connected through the ninth pipeline, and valve nine 28 is set on the ninth pipeline. After the experiment, open valve nine 28, and collect the tail gas in the high-pressure buffer tank one 3, valve three 17, three-way one 18, valve five 20, four-way one 21, reference tank one 4, valve six 22, four-way two 23, non-contact temperature measurement coal sample tank 5, valve seven 24, reference tank two 8, four-way two 23, three-way two 27, valve ten 29 and high-pressure buffer tank two 9 through the tail gas collection bag.

[0143] The first to ninth pipelines are φ3mm steel pipes with a maximum pressure bearing capacity of 20MPa.

[0144] Reference tank one 4 and reference tank two 8, valve five 20 and valve eight 26, four-way one 21 and four-way three 25 are symmetrically distributed with the central axis of the non-contact temperature measurement coal sample tank 5 as the symmetry axis to ensure that the free volume of the pipelines on both sides is consistent.

[0145] The method and device for testing the thermal effect of competitive adsorption of CH4 gas in coal seams replaced by CO2 provided in the embodiment of the present invention avoid the influence of pressure gradient on the replacement effect, and only consider the inverse diffusion process of CO2 "diffusion-adsorption" and CH4 "desorption-diffusion", which is helpful to deeply explore the replacement effect of CO2 on CH4 in coal seams, clarify the storage amount of CO2 and the desorption amount of CH4, and have important significance for CO2 storage and coalbed methane development in deep coal seams. In addition, the device adds a dry coal sample 38 temperature measurement system (infrared light high permeability single crystal 53 and infrared thermal imager 6), which can monitor the temperature change law of coal samples in the process of single-component gas adsorption / desorption and competitive adsorption of CO2 and CH4 in real time, which is convenient for analyzing the thermal effect characteristics of coal bodies in the process of CO2 replacing CH4 in coal seams, and is helpful to deeply explore the energy migration law and driving mechanism in the process of CO2 replacing CH4 in coal seams.

[0146] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0147] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for testing the heat effect of competitive adsorption of CH4 gas on CO2 coal seam, characterized in that: include: A dry coal sample is placed in a non-contact temperature measuring coal sample tank, and a free space volume V0 in the non-contact temperature measuring coal sample tank is measured; Set different ambient temperatures, CO2 and CH4 reciprocal diffusion and competitive adsorption to achieve the second equilibrium state pressure Repeat the first step multiple times to obtain multiple groups of first data groups to obtain η and ΔT relationship curves, each group of the first data group includes the CO2 and CH4 gas competitive adsorption replacement ratio η and the competitive adsorption equilibrium coal sample thermal effect ΔT; Wherein, the first step comprises: Obtain the initial amount of CH4 gas in the reference tank The non-contact temperature measuring coal sample tank is filled with CH4 gas through the reference tank to make the CH4 gas adsorb the dry coal sample, and the temperature change law of the dry coal sample during the adsorption process is monitored in real time until the adsorption reaches the first equilibrium state to obtain the first equilibrium temperature. First balance pressure Amount of CH4 gas adsorbed by dry coal sample The reference tank 2 is slowly filled with CO2 gas through the high-pressure buffer tank 2, and the pressure in the reference tank 2 is consistent with the pressure of the non-contact temperature measurement coal sample tank in the first equilibrium state. When the CO2 gas is stopped, the amount of CO2 gas in the reference tank 2 is obtained. And calculate the amount of CH4 gas in the non-contact temperature measuring coal sample tank The non-contact temperature measuring coal sample tank and the reference tank 2 are connected to allow CO2 and CH4 to diffuse and competitively adsorb each other, and the real-time temperature T of the dry coal sample, the pressure of the non-contact temperature measuring coal sample tank and the pressure of the reference tank 2 are monitored in real time until a second equilibrium state is reached, and a second equilibrium temperature under the second equilibrium state is obtained. Second balance pressure CO2 concentration CH4 concentration Competitive adsorption equilibrium Coal sample thermal effect The CH4 gas partial pressure is obtained by the first formula and CO2 gas partial pressure Among them, the first formula is: The amount of CH4 gas in the reference tank 2 and the non-contact temperature measurement coal sample tank is obtained by the second formula and the amount of CO2 gas Wherein, the second formula is: Among them, V r is the volume of reference tank 1, The second equilibrium pressure The CH4 gas compressibility factor, R gas constant, The second equilibrium pressure The CO2 gas compression factor is: Calculation of CH4 desorption CO2 adsorption Calculation of the competitive adsorption replacement ratio of CO2 and CH4 gases 2. The method for testing the heat effect of competitive adsorption of CH4 gas on CO2 coal seam according to claim 1 is characterized in that: Measuring the free space volume V0 in the non-contact temperature measuring coal sample tank includes: Repeat the second step multiple times to obtain multiple second data groups, each of which includes the first initial temperature T1 of the reference tank 1; the first initial pressure value P1 in the reference tank 1; the second initial temperature T2 of the non-contact temperature measuring coal sample tank; the second initial pressure P2 in the non-contact temperature measuring coal sample tank; the temperature T2 after the rare gas and the dry coal sample are in adsorption equilibrium; pin ; Pressure P after adsorption equilibrium between rare gas and dry coal sample pin ; According to the third formula and the plurality of the second data groups, a plurality of first equations are obtained, and the plurality of the first equations are solved simultaneously to obtain the free space volume V0 in the non-contact temperature measurement coal sample tank, wherein the third formula is: Wherein, V0 is the free space volume in the non-contact temperature measurement coal sample tank; V r is the volume of the reference tank 1; Y is the volume ratio; Z1 is the rare gas compression factor at the first initial pressure value P1 in the reference tank 1; Z pin is the pressure P after the adsorption equilibrium between the rare gas and the dry coal sample pin Z2 is the rare gas compression factor under the second initial pressure P2 in the contact temperature measurement coal sample tank; Wherein, the second step comprises: The high-pressure buffer tank 1, the reference tank 1 and the non-contact temperature measuring coal sample tank are evacuated; The reference tank is set to a first initial temperature T1 and the non-contact temperature measuring coal sample tank is set to a second initial temperature T2 by a constant temperature water bath; Filling the high-pressure buffer tank 1 with rare gas through a rare gas tank until the pressure in the high-pressure buffer tank 1 reaches a first preset pressure, and then stopping the input of rare gas; When the pressure in the inner cavity of the high-pressure buffer tank 1 is stable, the rare gas is slowly filled into the reference tank 1 through the high-pressure buffer tank 1. When the pressure in the reference tank 1 reaches the first initial pressure P1, the input of the rare gas is stopped, and the pressure in the non-contact temperature measurement coal sample tank is measured to be the second initial pressure P2; The reference tank 1 and the non-contact temperature measuring coal sample tank are connected until the pressure in the reference tank 1 and the pressure in the non-contact temperature measuring coal sample tank are stable and equal, and then balanced for 6h to 8h to obtain the pressure P after the adsorption equilibrium between the rare gas and the dry coal sample. pin , the temperature after the adsorption equilibrium between the rare gas and the dry coal sample is T pin .

3. The method for testing the heat effect of competitive adsorption of CH4 gas on CO2 coal seam according to claim 2, characterized in that: The amount of the initial substance of CH4 gas in the reference tank is obtained The non-contact temperature measuring coal sample tank is filled with CH4 gas through the reference tank to make the CH4 gas adsorb the dry coal sample, and the temperature change law of the dry coal sample during the adsorption process is monitored in real time until the adsorption reaches the first equilibrium state to obtain the first equilibrium temperature. First balance pressure Amount of CH4 gas adsorbed by dry coal sample include: Discharging the rare gas in the high-pressure buffer tank 1, the reference tank 1 and the non-contact temperature measurement coal sample tank; The high-pressure buffer tank 1, the reference tank 1 and the non-contact temperature measurement coal sample tank are evacuated; The reference tank is brought to a third initial temperature by a constant temperature water bath. Filling the high-pressure buffer tank 1 with CH4 gas through a CH4 gas tank until the pressure in the high-pressure buffer tank 1 reaches a second preset pressure, and then stopping the input of CH4 gas; When the pressure in the inner cavity of the high-pressure buffer tank 1 is stable, the CH4 gas is slowly filled into the reference tank 1 through the high-pressure buffer tank 1, and the reference tank 1 is at a third initial pressure. When , stop inputting CH4 gas; The initial amount of CH4 gas in the reference tank 1 is calculated by the fourth formula: The fourth formula is: in, V is the third initial pressure of the reference tank 1; r is the volume of the reference tank 1; The third initial pressure The CH4 gas compression factor is shown below; R is the gas constant; is the third initial temperature of the reference tank 1; The reference tank 1 and the non-contact temperature measuring coal sample tank are connected, and CH4 gas is filled into the non-contact temperature measuring coal sample tank through the reference tank 1 so that the CH4 gas adsorbs the dry coal sample, and the temperature change law of the dry coal sample during the adsorption process is monitored in real time until the adsorption reaches a first equilibrium state to obtain a first equilibrium temperature. First balance pressure Amount of CH4 gas adsorbed by dry coal sample The amount of CH4 gas in the reference tank 1 and the non-contact temperature measurement coal sample tank is calculated by the fifth formula The fifth formula is: In the formula, The first equilibrium pressure The compression factor of CH4 gas is: Amount of CH4 gas adsorbed by dry coal sample 4. The method for testing the heat effect of competitive adsorption of CH4 gas in CO2 coal seams according to claim 1 is characterized in that: Also includes: Collect the exhaust gas.

5. A CO2 coal bed CH4 gas competitive adsorption thermal effect test device, characterized in that: The method for testing the competitive adsorption thermal effect of CH4 gas in a CO2 coal seam according to claims 1 to 4 comprises: a CH4 gas tank, a rare gas tank, a high-pressure buffer tank 1, a reference tank 1, a non-contact temperature measuring coal sample tank, an infrared thermal imager, a data acquisition and storage mechanism, a reference tank 2, a high-pressure buffer tank 2, a CO2 gas tank, a constant temperature water bath, a vacuum pumping mechanism, a pressure gauge 1, a pressure gauge 2, a valve 1, a valve 2, a valve 3, a three-way 1, a valve 4, a valve 5, a four-way 1, a valve 6, a four-way 2, a valve 7, a four-way 3, a valve 8, a three-way 2, a valve 9, a valve 10, a valve 11, a valve 12, a pressure sensor 1, a pressure sensor 2, a pressure sensor 3, a CO2 concentration sensor and a CH4 concentration sensor; Connecting the CH4 gas tank to the high-pressure buffer tank 1 through a first pipeline, and setting the valve 1 on the first pipeline; Connecting the rare gas tank to the first high-pressure buffer tank through a second pipeline, and arranging the second valve on the second pipeline; The high-pressure buffer tank 1 is connected to the four-way 1 through a third pipeline, and the valve 3, the three-way 1, and the valve 5 are sequentially arranged on the third pipeline in a direction from the high-pressure buffer tank 1 to the four-way 1; The pressure gauge 1 is arranged on the high-pressure buffer tank 1; Connecting the three-way valve 1 and the vacuum pumping mechanism through a fourth pipeline, and arranging the valve 4 on the fourth pipeline; Connect the four-way one with the four-way two through a fifth pipeline, and set the valve six on the fifth pipeline; The reference tank 1 and the pressure sensor 1 are respectively connected to the four-way 1; The non-contact temperature measuring coal sample tank and the second pressure sensor are respectively connected to the second four-way; The four-way three and the high-pressure buffer tank two are connected through a sixth pipeline, and the valve eight, the three-way two and the valve ten are sequentially arranged on the sixth pipeline in a direction from the four-way three to the high-pressure buffer tank two; The second pressure gauge is arranged on the second high-pressure buffer tank; Connecting the CO2 gas tank and the second high-pressure buffer tank through a seventh pipeline, and setting the eleventh valve on the seventh pipeline; Connect the four-way two and the four-way three through an eighth pipeline, and set the valve seven on the eighth pipeline; The valve twelve is arranged on the output pipeline at the bottom of the high-pressure buffer tank one; The non-contact temperature measurement coal sample tank comprises a tank body, a tank cover and an infrared light high permeability single crystal; The can cover is arranged at the opening of the can body to close the can body, a mounting hole is arranged in the middle of the can cover, and the infrared light high permeability single crystal is arranged at the mounting hole; The infrared thermal imager is arranged above the infrared light high permeability single crystal; The reference tank 2 and the pressure sensor 3 are both connected to the four-way 3; The CO2 concentration sensor is arranged on the non-contact temperature measurement coal sample tank, and the CH4 concentration sensor is arranged on the reference tank 2; The pressure sensor 1, the pressure sensor 2, the pressure sensor 3, the CO2 concentration sensor, the CH4 concentration sensor, and the infrared thermal imager are all electrically connected to the data acquisition and storage mechanism; The reference tank 1, the non-contact temperature measurement coal sample tank and the reference tank 2 are arranged in the constant temperature water bath.

6. The CO2 coal bed CH4 gas competitive adsorption thermal effect testing device according to claim 5 is characterized in that: Also included are valve nine and exhaust collection bags; The tail gas collection bag and the tee two are connected via a ninth pipeline, and the valve nine is arranged on the ninth pipeline.

7. The CO2 coal bed CH4 gas competitive adsorption thermal effect testing device according to claim 5 is characterized in that: The reference tank 1 and the reference tank 2, the valve 5 and the valve 8, the four-way 1 and the four-way 3 are symmetrically distributed with the central axis of the non-contact temperature measurement coal sample tank as the axis of symmetry.

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