Method and device for analyzing sensitivity of methane gas adsorbed by coal to temperature and pressure
By using high-precision analysis equipment and TPV model, the problem of quantifying the dynamic law of coal adsorbed gas under non-isothermal pressure change conditions was solved, and accurate analysis of temperature and pressure sensitivity was achieved, thereby improving the efficiency of coalbed methane extraction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTH CHINA INSTITUTE OF SCIENCE & TECHNOLOGY (NATIONAL SAFETY TRAINING CENTER OF COAL MINES)
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-21
AI Technical Summary
Existing technologies cannot accurately characterize the dynamics of coal adsorbed gas under non-isothermal and variable pressure conditions, leading to inaccurate judgments on the effects of temperature and pressure, which restricts the application of enhanced mining technologies such as thermal injection.
A high-precision analytical device was designed, including a press, a precision heating furnace, a gas adsorption jar, a gas storage tank, a vacuum system, and a data acquisition system, to simultaneously monitor changes in temperature, pressure, and gas volume, and to analyze the sensitivity of coal to adsorb methane gas using a TPV model.
It achieves precise quantification of temperature and pressure sensitivity, has a wide range of applicability, and improves mining efficiency. In particular, under high temperature and high pressure conditions, the sensitivity of adsorption amount to temperature is significantly lower than that to pressure, which guides the optimization of thermal injection enhanced mining schemes.
Smart Images
Figure CN121899367A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of coal mine safety engineering and coalbed methane development technology, and in particular to a method and apparatus for analyzing the sensitivity of coal to adsorbed methane gas to temperature and pressure. Background Technology
[0002] In coalbed methane extraction, the amount of methane adsorbed by coal is a key parameter determining extraction efficiency, and it is influenced by both temperature and pressure. Currently, the industry mainly uses the following methods to analyze adsorption characteristics: The Langmuir equation is only applicable to isothermal conditions and cannot describe the adsorption behavior under temperature changes, which has significant limitations. The Dubinin-Astakhov (DA) equation attempts to combine temperature and pressure parameters, but it relies on saturated vapor pressure to calculate the adsorption potential. In gases with extremely low critical temperatures, such as methane, pseudo-saturated vapor pressure is required as a substitute, which leads to ambiguity in physical meaning and a decrease in calculation accuracy. Traditional experimental setups are mostly designed for single temperature or pressure conditions, lacking the ability to simultaneously control and monitor under high temperature and high pressure environments, and unable to quantify the sensitivity differences of temperature and pressure to adsorption.
[0003] The core flaw of existing technologies lies in their inability to accurately characterize the dynamic laws of coal adsorption of gas under non-isothermal and variable pressure conditions. This leads to inaccurate judgments on "which factor, temperature or pressure, has a more significant impact on the amount of adsorption," thus restricting the application of enhanced mining technologies such as thermal injection. Summary of the Invention
[0004] The purpose of this invention is to provide a method and apparatus for analyzing the sensitivity of coal to adsorbed methane gas to temperature and pressure, so as to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a method and apparatus for analyzing the sensitivity of coal to adsorbed methane gas to temperature and pressure, and a pressure stabilization system of a press for applying axial pressure to the adsorption vessel and maintaining stability, with a pressure control accuracy of ±0.01MPa; A precision heating furnace is used to heat the adsorption vessel placed inside, with a temperature control error of ±0.1℃; the gas adsorption vessel is a cylindrical metal container used to load coal samples, with high-temperature resistant sealing gaskets at both ends, and connected to the gas source and metering system via pipelines; a gas storage tank and gas metering device are used to store methane gas and accurately measure the gas volume changes during the experiment; a vacuum system is used to evacuate the adsorption vessel and pipelines before the experiment; and a data acquisition system is used to synchronously and in real time collect and record the temperature, pressure, and gas volume data inside the adsorption vessel.
[0006] Preferably, the precision heating furnace uses silicon carbide rod heating, and the working temperature range is 30~600℃; the gas adsorption jar has an inner diameter of φ100mm and a length of 200mm.
[0007] Preferably, the gas metering device includes a gas collecting cylinder and a precision pressure gauge, the gas collecting cylinder having an accuracy of ±0.01L and the pressure gauge having an accuracy of ±0.001MPa; the data acquisition system has a data sampling frequency of 1 time / second and a storage accuracy of 0.001 units.
[0008] Preferably, a method for analyzing the sensitivity of coal to methane gas adsorption to temperature and pressure using the aforementioned apparatus includes the following steps: coal sample preparation step: processing the coal sample into a cylinder of a predetermined size; system pretreatment step: placing the coal sample into an adsorption vessel, sealing it, evacuating it, and measuring the remaining volume of the adsorption vessel; gas injection equilibration step: injecting methane gas into the adsorption vessel to a set initial pressure and maintaining it at a constant temperature until adsorption equilibrium is reached; variable temperature testing step: starting from the initial temperature, gradually increasing the temperature in predetermined steps, maintaining a constant temperature at each temperature step point, and simultaneously recording the pressure and gas volume changes within the adsorption vessel; data modeling and sensitivity analysis step: based on the data obtained in the variable temperature testing step, establishing a temperature-pressure integrated adsorption model, and calculating the sensitivity coefficient KT of the adsorption amount to temperature and the sensitivity coefficient KP to pressure, quantifying the sensitivity difference by comparing KT and KP.
[0009] Preferably, in the variable temperature test step, the initial temperature is 30°C, the temperature increase step is 30°C, the maximum temperature is 270°C, and the temperature is kept constant for 2 hours at each temperature step point.
[0010] Preferably, the temperature-pressure integrated adsorption model is as follows: lnV = D0 - D1X1 + D2X2 - D3X3. Where V is the adsorption volume, T is the temperature, P is the pressure, and the independent variables are X1 = Tln(P / T²), X2 = T²ln(P / T²), X3 = T², and D0, D1, D2, and D3 are model parameters obtained by fitting experimental data.
[0011] Preferably, the formula for calculating the temperature sensitivity coefficient KT of the adsorption amount is: KT=|∂lnV / ∂T|P, and the formula for calculating the pressure sensitivity coefficient KP of the adsorption amount is: KP=|∂lnV / ∂P|T, wherein the partial derivative is calculated based on the temperature-pressure integrated adsorption model, and the coal sample is selected from coal types with different metamorphic degrees.
[0012] The technical effects and advantages of this invention are as follows: Improved device accuracy: Temperature control error ±0.1℃, pressure measurement accuracy ±0.001MPa, solving the problem that traditional devices cannot simultaneously monitor high temperature and high pressure; Wide model applicability: The TPV model overcomes the limitation of the DA equation above the critical temperature, and is applicable to the range of 30~270℃ and 0.1~5MPa, with a high fitting correlation coefficient. Sensitivity quantification is clear: experiments demonstrate the sensitivity of adsorption capacity to pressure at room temperature (18℃). ) is far lower than its sensitivity to temperature ( This provides a direct basis for enhanced mining through thermal injection; its application value is significant: it can guide the optimization of coalbed methane mining schemes. When the depressurization and desorption effects are poor, using thermal injection (such as 200℃) can reduce the adsorption amount by more than 30% and improve mining efficiency. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the principle structure of the experimental system of the present invention.
[0014] In the attached diagram: 1. Temperature controller; 2. Vacuum pump; 3. Gas storage tank; 4. Gas collecting cylinder; 5. Pressure gauge; 6. Adsorption jar; 7. Thermocouple; 8. Heating furnace. Detailed Implementation
[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0016] This invention provides, for example Figure 1 The present invention discloses a method and apparatus for analyzing the temperature and pressure sensitivity of coal adsorption of methane gas. The apparatus includes the following core components (Figure 1: Schematic diagram of high-temperature coal gas adsorption measurement system): Press and pressure stabilizing system: Provides axial pressure (0~30 MPa) to ensure the adsorption jar 6 is sealed under high temperature and high pressure. It adopts servo control technology and the pressure control accuracy is ±0.01 MPa. Precision heating furnace 8: It adopts silicon carbide rod heating, with a temperature range of 30~600℃ and a temperature control error of ±0.1℃. It is equipped with thermocouples to monitor the coal sample temperature in real time. Gas adsorption jar: A cylindrical metal container with an inner diameter of φ100mm and a length of 200mm, with high-temperature resistant sealing gaskets at both ends, and connected to the gas storage tank and gas collection system through a φ4 metal tube; Gas storage tank and gas metering device: 5L high-pressure gas storage tank (pressure resistant 10 MPa), equipped with gas collecting cylinder (accuracy ±0.01 L) and pressure gauge (accuracy ±0.001 MPa). Vacuum system: Rotary vane vacuum pump (ultimate vacuum ≤ 1 Pa), used to remove residual gas in the pores of the coal sample before the experiment; Data acquisition system: synchronously records temperature, pressure, and gas volume data, with a sampling frequency of 1 time / second and a storage accuracy of 0.001 units.
[0017] (II) Experimental Methods and Procedures Coal sample preparation: The coal samples were processed into cylinders with a diameter of φ100 mm × 150 mm. Coal samples with different metamorphic degrees, such as lean coal from Tunliu Mine, anthracite from Kaiyuan Mine, and coking coal from Xiangning Mine, were selected to ensure representativeness. System pretreatment: The coal sample is placed in the adsorption vessel, sealed, and vacuumed for 4 hours. The remaining volume of the adsorption vessel (the gap between the coal sample and the container and the pore volume of the coal body) is measured. Gas injection equilibration: Inject methane gas into the adsorption jar to the set initial pressure (0.1~0.6 MPa), keep it at a constant temperature (30℃) for 8 hours to ensure adsorption equilibrium; Temperature variation test: Starting from 30℃, the temperature is increased by 30℃ and held for 2 hours. The pressure and gas volume changes inside the adsorption vessel are recorded until 270℃. Each temperature point is repeated 3 times. Data Modeling: Based on experimental data, a temperature-pressure combined adsorption model (TPV) is established using the Dubinin-Radushkevich equation and Boltzmann's energy distribution law. The formula is as follows:
[0018] in, , , , , , , , are the fitting parameters; Sensitivity analysis: Calculate the sensitivity coefficient of adsorption amount to temperature. and the sensitivity coefficient to pressure Through comparison ,and 1. Determine the differences in sensitivity.
[0019] Key structural features of the device: An integrated adsorption testing device that integrates a press, a precision heating furnace, a vacuum system, and a data acquisition system. Its features include: a coaxial design between the adsorption tank and the heating furnace, and a synchronous monitoring module for temperature, pressure, and gas volume. Methodological innovation: A sensitivity analysis method based on the temperature-pressure combined adsorption model (TPV), including the following steps: coal sample pretreatment → temperature-pressure swing adsorption experiment → TPV model fitting → and Calculation and comparison; Model parameters: In the TPV model, , , Definition and fitting parameters, , , , The solution method.
[0020] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. An apparatus for analyzing the sensitivity of coal to adsorb methane gas to temperature and pressure, characterized in that, The pressure stabilizing system of the press is used to apply axial pressure to the adsorption vessel and maintain stability; A precision heating furnace is used to heat the adsorption jar placed inside it; the gas adsorption jar is a cylindrical metal container used to load coal samples, with high-temperature resistant sealing gaskets at both ends, and connected to the gas source and metering system through pipelines; the gas storage tank and gas metering device are used to store methane gas and accurately measure the gas volume change during the experiment; the vacuum system is used to evacuate the adsorption jar and pipelines before the experiment. The data acquisition system is used to synchronously and in real time collect and record temperature, pressure, and gas volume data inside the adsorption jar.
2. The apparatus according to claim 1, characterized in that, The precision heating furnace uses silicon carbide rod heating, and the working temperature range is 30~600℃; the gas adsorption jar has an inner diameter of φ100mm and a length of 200mm.
3. The apparatus according to claim 2, characterized in that, The gas metering device includes a gas collecting cylinder and a precision pressure gauge. The gas collecting cylinder has an accuracy of ±0.01L, and the pressure gauge has an accuracy of ±0.001MPa. The data acquisition system has a data sampling frequency of 1 time / second and a storage accuracy of 0.001 units.
4. A method for analyzing the temperature and pressure sensitivity of coal adsorbed methane gas using the apparatus described in any one of claims 1-3, characterized in that, Includes the following steps: Coal sample preparation steps: Process the coal sample into a cylinder of predetermined size; System pretreatment steps: Place the coal sample into an adsorption vessel, seal it, evacuate it, and measure the remaining volume of the adsorption vessel; Gas injection equilibration steps: Inject methane gas into the adsorption vessel to the set initial pressure and maintain it at a constant temperature until adsorption equilibrium is reached; Temperature variation test steps: Starting from the initial temperature, increase the temperature stepwise at predetermined steps, maintain a constant temperature at each temperature step point, and simultaneously record the pressure and gas volume changes in the adsorption vessel; Data modeling and sensitivity analysis steps: Based on the data obtained from the temperature variation test steps, establish a temperature-pressure integrated adsorption model, and calculate the sensitivity coefficient KT of the adsorption amount to temperature and the sensitivity coefficient KP to pressure. Quantify the sensitivity differences by comparing KT and KP.
5. The method for analyzing the sensitivity of coal to adsorbed methane gas to temperature and pressure according to claim 4, characterized in that, In the variable temperature test step, the initial temperature is 30°C, the temperature increment is 30°C, the maximum temperature is 270°C, and the temperature is maintained at each temperature step point for 2 hours.
6. The method for analyzing the sensitivity of coal to adsorbed methane gas to temperature and pressure according to claim 5, characterized in that, The temperature-pressure integrated adsorption model is as follows: lnV=D0-D1X1+D2X2-D3X3. Where V is the adsorption volume, T is the temperature, P is the pressure, and the independent variables are X1=Tln(P / T²), X2=T²ln(P / T²), X3=T², and D0, D1, D2, and D3 are model parameters obtained by fitting experimental data.
7. The method for analyzing the sensitivity of coal to adsorbed methane gas to temperature and pressure according to claim 1, characterized in that, The formula for calculating the temperature sensitivity coefficient KT of the adsorption amount is: KT=|∂lnV / ∂T|P, and the formula for calculating the pressure sensitivity coefficient KP of the adsorption amount is: KP=|∂lnV / ∂P|T, where the partial derivative is calculated based on the temperature-pressure integrated adsorption model, and the coal sample is selected from coal types with different metamorphic degrees.