High-pressure liquid nitrogen cyclic cracking and gasification displacement experimental device for coal-rock sample

Abstract

The invention discloses a high-pressure liquid nitrogen cyclic cracking and gasification displacement experimental device for a coal-rock sample. The device comprises a liquid nitrogen tank, a confining pressure loading system and an axial compression loading system; the confining pressure loading system and the axial compression loading system are cross-connected; a high-pressure reaction kettleis mounted at a central position of an area surrounded by the confining pressure loading system and the axial compression loading system; the liquid nitrogen tank is connected with a liquid nitrogen pulse boosting pump through a pipeline; and an ultra-low temperature resistant flowmeter is mounted on the pipeline between the liquid nitrogen tank and the liquid nitrogen pulse boosting pump. According to the high-pressure liquid nitrogen cyclic cracking and gasification displacement experimental device for the coal-rock sample, through different liquid nitrogen injection methods, the microscopicstructure characteristics of a coal body are changed, the evolution of coal body fissures is promoted, the permeability of the coal body is increased, and through the gasification of high-pressure nitrogen, the partial pressure of the coal body is changed, and the competitive adsorption relationship between the nitrogen and gas is promoted, so that the gas in the coal body is desorbed from the coal body with a nitrogen gas flow.

Description

technical field [0001] The invention relates to the technical field of coal, in particular to an experimental device for high-pressure liquid nitrogen circulation cracking and gasification displacement of coal rock samples. Background technique [0002] Liquid nitrogen has an extremely low temperature (-196°C), no pollution to the environment, easy preparation and low cost. Coal is a natural geological body with low strength, cleats, micro-cracks and pores and other defective structures. After multi-stage pulse injection of low-temperature liquid nitrogen into the coal body, it can weaken the freezing damage of the coal body, expand the original micro-cracks and generate new ones. Cracks, forming freeze-thaw fracturing zones. The volume of liquid nitrogen expands rapidly after gasification (1m 3 After gasification of liquid nitrogen, the volume reaches 696m at 21°C 3 ), generating huge expansion force to crack the coal seam and form a gasification high-pressure fracturing...

AI Technical Summary

Problems solved by technology

In the past, when studying the liquid nitrogen permeation enhancement technology of coal seams, most of them focused on the single effects of liquid nitrogen immersion fracturing, high pressure fracturing, and displacement and desorption of gas. For deep coal bodies, the above composite effects are more complicated

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