A Coal/Shale Isothermal Adsorption Experimental Method

Abstract

The invention provides a coal / shale isothermal adsorption experiment method. The method is carried out by a reference kettle, a sample kettle and a middle region of an experiment device; a sample to be detected is placed in the sample kettle and an experiment temperature is set to be constant according to actual stratum conditions; the sample kettle is calibrated to obtain a free space volume of the sample kettle; the reference kettle and the sample kettle are vacuumized to obtain the initial pressure of the sample kettle; the middle region is communicated with the reference kettle and the middle region is separated from the sample kettle; enough amount of adsorbate gas is injected into the reference kettle one time; after the pressure in the middle region is balanced with the pressure in the reference kettle, the initial pressure of the reference kettle is obtained; an adsorption experiment is carried out to obtain the pressure of the reference kettle and the pressure of the sample kettle after adsorption is balanced; according to a mass conservation principle before and after each time of adsorption, the adsorption amounts under different sample kettle pressures after a plurality of times of adsorption balance are obtained by using the initial pressure of the sample kettle, the initial pressure of the reference kettle, the free space volume of the sample kettle and the pressure of the reference kettle and the pressure of the sample kettle in an adsorption process.

Description

technical field [0001] The invention relates to the field of adsorption measurement, in particular to a coal / shale isothermal adsorption experiment method. Background technique [0002] At present, there are two main experimental methods for measuring gas adsorption isotherms: volumetric method and gravimetric method. Among them, the volumetric method is divided into constant volume type and constant pressure type according to different gas injection methods. [0003] Constant volume volumetric method, as the most commonly used method, its experimental device is mainly composed of gas cylinders, vacuum pumps, booster pumps, reference kettle, sample kettle, pressure and temperature sensors, and thermostat box. Inject the adsorbate gas into the medium, record the pressure of the reference tank after the pressure is stable, then open the intermediate valve between the reference tank and the sample tank, let the gas expand isothermally and enter the sample tank, wait for the ad...

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Problems solved by technology

[0007] The experimental equipment required by the traditional volumetric method is simple and easy to operate, but the experimental operation of multiple gas injections will cause multiple accumulations of measurement errors, resulting in large experimental errors in measurement results, which may eventually cause abnormal adsorption isotherms. This method is only suitable for adsorbents (such as activated carbon, etc.) with large adsorption capacity (small measurement error), and it will cause large errors in the measurement of coal / shale with very low adsorption gas capacity, which will seriously affect the experimental results.

Although the patent CN102607991A has the ability to measure the adsorption capacity of coal / shale, and proposes the use of pneumatic valves for automatic program control to simulate high reservoir pressure, but its principle is the constant volume volume method, the error of the measurement results is still large, and the Can not guarantee accurate measurement of adsorption capacity of different gases in coal / shale under actual formation conditions such as high temperature and high pressure

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