Breakdown and destruction of heterogeneous solid dielectrics by high voltage pulses

Lisitsyn, I.V.; Inoue, Hirotoshi; Nishizawa, Izumi; Katsuki, S.; Akiyama, H.

doi:10.1063/1.368946

Cited by 78 publications

(69 citation statements)

References 4 publications

(3 reference statements)

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“…Though this has been identified as one of the fragmentation mechanisms with minimal environmental impacts [29][30][31][32][33], to date, this technology has however not been largely accepted by the mining and energy industry due to the huge transition that needs to be made from well-established mechanical disintegration processes [30]. Basically, the electrical disintegration of rock has limited application, mainly in the mineral liberation process, in which the generating current can be controlled.…”

Section: Electrical Disintegrationmentioning

confidence: 99%

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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Global energy and material consumption are expected to rise in exponential proportions during the next few decades, generating huge demands for deep earth energy (oil/gas) recovery and mineral processing. Under such circumstances, the continuation of existing methods in rock fragmentation in such applications is questionable due to the proven adverse environmental impacts associated with them. In this regard; the possibility of using more environmentally friendly options as Soundless Chemical Demolition Agents (SCDAs) play a vital role in replacing harmful conventional rock fragmentation techniques for gas; oil and mineral recovery. This study reviews up to date research on soundless cracking demolition agent (SCDA) application on rock fracturing including its limitations and strengths, possible applications in the petroleum industry and the possibility of using existing rock fragmentation models for SCDA-based rock fragmentation; also known as fracking. Though the expansive properties of SCDAs are currently used in some demolition works, the poor usage guidelines available reflect the insufficient research carried out on its material's behavior. SCDA is a cementitious powdery substance with quicklime (CaO) as its primary ingredient that expands upon contact with water; which results in a huge expansive pressure if this CaO hydration reaction occurs in a confined condition. So, the mechanism can be used for rock fragmentation by injecting the SCDA into boreholes of a rock mass; where the resulting expansive pressure is sufficient to create an effective fracture network in the confined rock mass around the borehole. This expansive pressure development, however, dependent on many factors, where formation water content creates a negative influence on this due to required greater degree of hydration under greater water contents and temperature creates a positive influence by accelerating the reaction. Having a precise understanding of the fracture propagation mechanisms when using SCDA is important due to the formation of complex fracture networks in rocks. Several models can be found in the literature based on the tangential and radial stresses acting on a rock mass surrounding an SCDA charged borehole. Those fracture models with quasi-static fracturing mechanism that occurs in Mode I type tensile failure show compatibility with SCDA fracturing mechanisms. The effect of borehole diameter, spacing and the arrangement on expansive pressure generation and corresponding fracture network generation is important in the SCDA fracturing process and effective handling of them would pave the way to creating an optimum fracture network in a targeted rock formation. SCDA has many potential applications in unconventional gas and oil recovery and in-situ mining in mineral processing. However, effective utilization of SCDA in such application needs much extensive research on the performance of SCDA with respect to its potential applications, particularly when considering unique issues arising in using SCDA in different ...

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Section: Electrical Disintegrationmentioning

confidence: 99%

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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“…However, the fact that for very short voltage pulses, the breakdown inside the solid dielectric occurs faster than the surface flashover between the electrodes, is discovered in early sixties by Vorobiev and Vorobiev. 8 It is also shown that the most of solid dielectrics can be broken down in insulating liquids like transformer oil. In our experiments, the rising-time of high voltage pulses is only about 100 ns.…”

Section: Evidences Of Plasma Penetration Inside the Granitementioning

confidence: 99%

“…It was shown that the most of the solid dielectrics can be broken down in the insulating liquids like transformer oil, and compared to other liquid like water, the dielectric strength of transformer oil is higher. 3,8 Therefore, the transformer oil is selected as the liquid surrounding the rocks. Moreover, to enhance the electric strength around the electrode tips, two steel needles with a diameter of 1.2 mm is selected as the electrodes and the tips of the needles are placed on the interface between the transformer oil and the rock.…”

Section: Two-electrode Systemmentioning

confidence: 99%

“…4 In early sixties, it was also found that for very short voltage pulses, the breakdown inside the solid dielectric occurs faster than the surface flashover between the electrodes. 8 It seems that discharge channels can penetrate in solids as long as the voltage duration is short and the voltage amplitude is high. 9 The second stage realization depends on the storage energy of generator energy and the time of the energy introduction into the discharge channel.…”

Section: Introductionmentioning

confidence: 99%

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Discharge characteristics of high voltage pulses inside rocks with increasing their applied number

Zhang

Liu

et al. 2017

AIP Advances

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By conducting experiments for granite and sandstone samples under different conditions, such as voltage amplitude and electrodes gap, the discharge characteristics of high voltage pulses inside the rocks with increasing their applied number have been investigated. In each of the experiments, a certain value for voltage amplitude and electrodes gap is set separately and then, pulses are applied on same surface of the rocks continuously. The time dependent voltage between the electrodes, the current in plasma and the transient states around the electrode tips are measured and recorded separately when each of the pulses is applied. By means of the wave forms of the voltage and the current, variation laws of the discharging time and the energy release into the plasma with increasing applied pulses number have been obtained. The relation between the number of applied pulses and the critical condition of discharge inside of the rocks has been found. Further, the relation between the number of applied pulses required to discharge and the voltage amplitude has been also analyzed. The reasons of why increasing applied pulses number has such effects on discharge characteristics of them inside the granite and sandstone samples have been found and demonstrated.

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“…Extraction of geothermal energy encounters fracturing rocks due to temperature gradients [11] and shrinkage due to cooling or drying causes cracks in basalt columns with specific spacings [12]. Dielectric breakdown of insulators [13][14][15], may also be modeled with the proposed peridynamic theory. Instead of having a conducting body with growing insulated cracks, in this case the body is an insulator in which conducting cracks grow and interact dynamically.…”

Section: Motivationmentioning

confidence: 99%

A peridynamic formulation for transient heat conduction in bodies with evolving discontinuities

Bobaru

Duangpanya

2012

Journal of Computational Physics

250

142

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We introduce a multidimensional peridynamic formulation for transient heat-transfer. The model does not contain spatial derivatives and uses instead an integral over a region around a material point. By construction, the formulation converges to the classical heat transfer equations in the limit of the horizon (the nonlocal region around a point) going to zero. The new model, however, is suitable for modeling, for example, heat flow in bodies with evolving discontinuities such as growing insulated cracks. We introduce the peridynamic heat flux which exists even at sharp corners or when the isotherms are not smooth surfaces. The peridynamic heat flux coincides with the classical one in simple cases and, in general, it converges to it in the limit of the peridynamic horizon going to zero. We solve test problems and compare results with analytical solutions of the classical model or with other numerical solutions. Convergence to the classical solutions is seen in the limit of the horizon going to zero. We then solve the problem of transient heat flow in a plate in which insulated cracks grow and intersect thus changing the heat flow patterns. We also model heat transfer in a fiber-reinforced composite and observe transient but steep thermal gradients at the interfaces between the highly conductive fibers and the low conductivity matrix. Such thermal gradients can lead to delamination cracks in composites from thermal fatigue. The formulation may be used to, for example, evaluate effective thermal conductivities in bodies with an evolving distribution of insulating or permeable, possibly intersecting, cracks of arbitrary shapes.

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Breakdown and destruction of heterogeneous solid dielectrics by high voltage pulses

Cited by 78 publications

References 4 publications

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

Discharge characteristics of high voltage pulses inside rocks with increasing their applied number

A peridynamic formulation for transient heat conduction in bodies with evolving discontinuities

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