Mechanism Analysis of Liquid Carbon Dioxide Phase Transition for Fracturing Rock Masses

The technique of breaking rocks using carbon dioxide phase transition technology is being widely applied in current research. This article combines theoretical and practical methods to analyze the mechanism by which high-pressure gas breaks rock at different stages. Using the observation that liquid carbon dioxide forms a high-pressure jet from release holes at the moment of release, a formula for calculating the initial pressure on the wall in the direction of release was obtained, and the pattern of initial crack formation on the borehole wall under different initial stress conditions was examined. An experiment using carbon dioxide phase transition technology to fracture rock without an initial stress field was conducted. The mechanism of generation and expansion of subsequent cracks under stress waves and high-pressure gas was analyzed, and the formula for calculating crack propagation radius under stress waves was obtained. The results suggested that under the quasi-static action of high-pressure gas, cracks begin to develop when the stress intensity factor KI at the crack tip is equal to or greater than the fracture toughness KIC of the rock.

Download Full-text

Positive Phase Pressure Function and Pressure Attenuation Characteristic of a Liquid Carbon Dioxide Blasting System

Energies ◽

10.3390/en12214134 ◽

2019 ◽

Vol 12 (21) ◽

pp. 4134

Author(s):

Bo Ke ◽

Keping Zhou ◽

Gaofeng Ren ◽

Ji Shi ◽

Yanan Zhang

Keyword(s):

Phase Transition ◽

Carbon Dioxide ◽

High Pressure ◽

Impact Pressure ◽

Positive Phase ◽

Liquid Carbon ◽

Edge Zone ◽

Liquid Carbon Dioxide ◽

The Impact ◽

Phase Pressure

As environmental requirements become more stringent, the liquid carbon dioxide blasting system is one of the non-explosive blasting technologies that, with low tensile stress energy, will replace the chemical explosive blasting technology, and the impact pressure characteristic of high-pressure fluid is a crucial factor in the process of rock breaking. To further investigate the impact and pressure attenuation characteristics of high-pressure fluid during the phase transition of liquid carbon dioxide blasting system, the pressure curves of high-pressure fluid in liquid carbon dioxide blasting systems at different distances were measured in the laboratory. Based on the mechanism analysis of phase transition kinetics, the initial jet velocity of the four experiments was calculated, and the rationality of results was verified by the Bernoulli equation. The general expression of the positive phase pressure–time function was proposed, and the idealized impact pressure curve can be divided into five stages. The impact pressure field of the liquid carbon dioxide blasting system can be divided into three areas at different distances: the explosive jet impact zone, the jet edge zone and the shock wave action zone, and the pressure–contrast distance fitting equation of the liquid carbon dioxide blasting system were obtained.

Download Full-text

Expert and gray box modeling of high pressure liquid carbon dioxide extraction of Pimpinella anisum L. seed

The Journal of Supercritical Fluids ◽

10.1016/j.supflu.2012.09.002 ◽

2012 ◽

Vol 72 ◽

pp. 213-222 ◽

Cited By ~ 5

Author(s):

Meysam Davoody ◽

Gholamreza Zahedi ◽

Mazda Biglari ◽

M.A.A. Meireles ◽

Alireza Bahadori

Keyword(s):

Carbon Dioxide ◽

High Pressure ◽

Liquid Carbon ◽

Liquid Carbon Dioxide ◽

Pimpinella Anisum ◽

Carbon Dioxide Extraction

Download Full-text

Hydrophobic modification of fibers by pressure-induced phase-separation coupled with ultrasonic irradiation in high-pressure liquid carbon dioxide

Chemical Engineering Journal ◽

10.1016/j.cej.2014.02.055 ◽

2014 ◽

Vol 246 ◽

pp. 106-113 ◽

Cited By ~ 10

Author(s):

Kiyoshi Matsuyama ◽

Satoshi Tanaka ◽

Tetsuya Okuyama

Keyword(s):

Carbon Dioxide ◽

High Pressure ◽

Phase Separation ◽

Ultrasonic Irradiation ◽

Hydrophobic Modification ◽

Liquid Carbon ◽

Liquid Carbon Dioxide

Download Full-text

Experimental Study on Explosion Pressure and Rock Breaking Characteristics under Liquid Carbon Dioxide Blasting

Advances in Civil Engineering ◽

10.1155/2018/7840125 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Yanan Zhang ◽

Junren Deng ◽

Bo Ke ◽

Hongwei Deng ◽

Jielin Li

Keyword(s):

Carbon Dioxide ◽

High Pressure ◽

Free Field ◽

Jet Impingement ◽

Rock Breaking ◽

Tensile Failure ◽

Liquid Carbon ◽

Liquid Carbon Dioxide ◽

Explosion Pressure ◽

The Impact

A liquid carbon dioxide blasting experiment was carried out under free field conditions, alongside a liquid carbon dioxide rock breaking experiment, to investigate explosion pressure variation and rock breaking characteristics under liquid carbon dioxide blasting. The experimental results show that the internal and external explosion pressures of the liquid carbon dioxide fracturing devices all rapidly increased at first, before attenuating vibrantly after blasting. When the explosion pressure was raised, the internal explosion pressure increased first exponentially and then linearly, while the external explosion pressure increased exponentially throughout. The duration time of the blasting effect stage was about 45 ms. Under the combined effect of jet impingement and a gas wedge of high-pressure carbon dioxide, the rock is subjected to tensile failure. The impact failure and the “gas wedge effect” of high-pressure carbon dioxide play a key role in the rock breaking of liquid carbon dioxide blasting technology.

Download Full-text

Increasing Permeability of Coal Seam and Improving Gas Drainage Using a Liquid Carbon Dioxide Phase Transition Explosive Technology

Advances in Civil Engineering ◽

10.1155/2018/3976505 ◽

2018 ◽

Vol 2018 ◽

pp. 1-15 ◽

Cited By ~ 2

Author(s):

Wenrui He ◽

Fulian He ◽

Kun Zhang ◽

Yongqiang Zhao ◽

Hengzhong Zhu

Keyword(s):

Phase Transition ◽

Carbon Dioxide ◽

Numerical Simulation ◽

Blast Hole ◽

Liquid Carbon ◽

Gas Drainage ◽

Liquid Carbon Dioxide ◽

Drainage Hole ◽

Drainage Effect ◽

Coal Damage

The low permeability of coal seams makes gas drainage difficult in lots of coal mines. This study presents a low-temperature, safe, and efficient liquid carbon dioxide phase transition explosive technology (LCDPTET) to increase the permeability of coal, thereby improving the efficiency of gas drainage and eliminating the dangers of coal and gas outburst. Meanwhile, an integrated approach for experimental determination, numerical simulation, and field testing was applied to study the damage ranges of coal and to determine a reasonable spacing between the gas drainage hole and blast hole. A numerical simulation model of liquid carbon dioxide phase transition explosion (LCDPTE) was built, and the damage index M was introduced to analyze the degree and range of coal damage after explosion at different spacings between the blast hole and the gas drainage hole. Furthermore, another aim was the assessment of the permeability changes and comparison of the gas drainage effects of different borehole spacings. The results showed that as the borehole spacing became smaller, the degree of coal damage around the gas drainage hole increased, and the gas drainage effect improved. However, to avoid the collapse of the gas drainage hole, the gas drainage holes should not be located in the crushing zone caused by LCDPTE. Based on the numerical analysis conducted to guide the borehole arrangement of the field test, the latter was carried out to study the increasing ranges of permeability of coal and the drainage effect after explosion. The results indicated that LCDPTET could greatly improve the permeability of the coal seam and gas drainage efficiency. In addition, this new technology could not only improve the safety and efficiency of mine production but could also turn carbon dioxide into an effective energy source worthy of popularization and application.

Download Full-text