Dielectric properties of coal

Marland, S.; Merchant, A.J.; Rowson, Neil A.

doi:10.1016/s0016-2361(01)00050-3

Cited by 218 publications

(68 citation statements)

References 9 publications

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“…Therefore, it can be assumed that during the coal gasification process (comprising a heating and cooling phase) the water can affect radar waves propagation in early and late phases of process. This was confirmed in research tests carried out on British coals (Marland et al 2001). …”

Section: Propagation Of Electromagnetic Waves In Coal and Gasificatiosupporting

confidence: 62%

Sensing underground coal gasification by ground penetrating radar

Kotyrba

Stańczyk

2017

Acta Geophys.

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The paper describes the results of research on the applicability of the ground penetrating radar (GPR) method for remote sensing and monitoring of the underground coal gasification (UCG) processes. The gasification of coal in a bed entails various technological problems and poses risks to the environment. Therefore, in parallel with research on coal gasification technologies, it is necessary to develop techniques for remote sensing of the process environment. One such technique may be the radar method, which allows imaging of regions of mass loss (voids, fissures) in coal during and after carrying out a gasification process in the bed. The paper describes two research experiments. The first one was carried out on a large-scale model constructed on the surface. It simulated a coal seam in natural geological conditions. A second experiment was performed in a shallow coal deposit maintained in a disused mine and kept accessible for research purposes. Tests performed in the laboratory and in situ conditions showed that the method provides valuable data for assessing and monitoring gasification surfaces in the UCG processes. The advantage of the GPR method is its high resolution and the possibility of determining the spatial shape of various zones and forms created in the coal by the gasification process.

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Section: Propagation Of Electromagnetic Waves In Coal and Gasificatiosupporting

confidence: 62%

Sensing underground coal gasification by ground penetrating radar

Kotyrba

Stańczyk

2017

Acta Geophys.

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“…As the lignite coal used in the described reactor was of low rank and was characterized by a high‐ moisture content (Table ), it could therefore be assumed that only the porosity and water content of the reactor components would have an impact on any change in their electric properties, with electrical conductivity rather than dielectric permittivity being affected when coal temperature exceeded 150° C. This assumption is backed up by the results of a series of heating and cooling tests carried out on British coals (Marland et al ), which revealed that moisture content has a significant influence on the dielectric constant of coal only during heating within a temperature range from 40–160° C (Fig. ).…”

Section: Model Descriptionmentioning

confidence: 99%

Application of a GPR technique for the monitoring of simulated underground coal gasification in a large‐scale model

Kotyrba

Stańczyk

2013

Near Surface Geophysics

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Underground Coal Gasification (UCG) involves the recovery of energy from a coal deposit via the use of controlled combustion. A reactor equipped with apparatus enabling the analysis of temperature profiles and gas composition was constructed for the simulation of underground conditions, both with respect to the coal seam and the surrounding stratum characteristics. A three day experiment was performed in which large blocks of lignite were gasified, with an average gasification rate of 5 kg/h. The ground‐penetrating radar (GPR) reflection method was used to monitor the process and observe physical and structural changes taking place within the gasification zone; radar images of the different stages of the process were then recorded and analysed. The experiment demonstrated the potential for successful application of radar techniques in the observation and monitoring of the coal gasification process in a natural environment. Whereas the gasification of coal in shallow seams could be monitored by surface measurements, that of deep seams in operating coal mines or coal deposits could be monitored by measurements made from galleries or boreholes.

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“…Conduction losses due to residual charges in apatites [45], ions formed during the degradation (free radicals, anions and cations [46][47][48]), ionic products resulting from the degradation of carbonates (calcite, dolomite), dehydration of clays [49,50] and hydroxyapatites [45], decarbonation of carbonated apatites, the conversion of pyrite into pyrrotite [51] and polar products presenting significant dielectric properties [52][53][54][55][56][57][58][59]. Similar observations were made during the pyrolysis of coal [60] and oil shale under microwaves [61][62][63][64].…”

Section: Influence Of the Microwave Powermentioning

confidence: 99%