Semi‐industrial tests on enhanced underground coal gasification at Zhong‐Liang‐Shan coal mine

Wang, G. X.; Wang, Z. T.; Feng, Bo; Rudolph, Victor; Jiao, Jian

doi:10.1002/apj.337

Cited by 36 publications

(14 citation statements)

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“…16 also indicates that the LHV of the product gas had its highest value between 0.9 to 1.65 MPa and it seems that above around 2 MPa the LHV decreases which is in good agreement with the carbon conversion and CGE result. Furthermore this finding agrees with a semi industrial test conducted with a coking coal (60% F.C, 16% V.M., LHV 26 MJ/kg) gasified with air and steam, aiming to investigate the effect of cyclically changing the operational pressure in terms of the quality of the product gas [26]. The gas composition was 15-25 % CO, 5-8% CH 4 and 10-30% H 2 which is in good agreement with the gas composition produced at pressures in this study for CO and H 2 during the reduction zone as shown in Table 5 and Fig.…”

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confidence: 87%

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Konstantinou

Marsh

2015

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Underground Coal Gasification (UCG) is the process by which unmineable coal resources are converted in situ into a combustible gas. Pressurised oxidants such as steam and air or oxygen are injected into the coal seam in order to react with coal and form a product gas. The main gases produced are H 2 , CO, CH 4 and CO 2 , in proportions depending on temperature, pressure and the composition of the reactant gases injected [1][2][3]. Although it can be challenging to accurately measure or reproduce these conditions in a reliable fashion, it is generally believed that at high enough temperatures, free oxygen reacts completely with the solid carbon within a relatively short distance from the injection point. The heat evolved acts to pyrolyse the adjacent coal and the char formed then reacts with carbon dioxide, steam or other gases formed by combustion and pyrolysis [4][5][6]. The key substance, and hence driver of the net gasification process under these conditions is therefore CO 2 which is produced during the oxidation zone [5,7,8]. At the reduction zone CO 2 and steam, which is either introduced deliberately into the cavity or is flowing into the cavity from the oxidation of the surrounding strata, reacts with char and produces around 60% of the total gas product (by volume) during the UCG process. The remaining 40% is produced during the devolatilisation phase, although this is highly dependent on reactor condition, the type of coal and the gaseous reactants [4]. Fig. 1 illustrates the three reaction zones of a reacting channel during a UCG process, which are the oxidation, reduction and pyrolysis zones. During the oxidation zone, as the coal is consumed more coal falls into the growing void, which creates a high coal surface area available for reaction and permits contact between the hot gases and the coal [5,7]. This area is the final reduction zone which converts excess CO 2 to CO and is responsible for the uniform quality of the product gas. Measurement of the upstream gas composition in the oxidation zone has shown comparatively low heating values which demonstrate that the reactions in the oxidation zone do not have such a significant effect on the product gas composition [8,9]. Finally the pyrolysis zone is where the devolatilisation of the coal takes place, forming char that contains active sites for subsequent gas-solid reactions.Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification AbstractThis paper describes an experimental investigation to determine the impact of pressurised reactor conditions within the reduction zone of a gasification process employing a semi-batch reactor with a bituminous coal. The conditions examined with this bespoke pressurised rig were designed to be representative of an Underground Coal Gasification (UCG) process, at pressures up to 3.0 MPa and temperatures up to 900 °C; coal samples were approximately 36 g per test. Current published literature suggests that one ...

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confidence: 87%

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Konstantinou

Marsh

2015

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“…In the Yanzhou coal mine in Shandong Province, China, there is a plan to carry out an underground coal gasification (UCG) industrial trial. The UCG is a mining technology that burns coal in a controlled manner for producing combustible gas, so the high-temperature gas flow in the combustion space area would bake the surrounding rocks by convective and radiative heat transfer and make the surrounding rocks reach about 1200 • C [61,62]. High temperatures would change the physical and mechanical properties of the granite layer above the coal seam, which affects its stability and the safety of the gasifier in the UCG stope.…”

Section: Introductionmentioning

confidence: 99%

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

et al. 2019

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In deep geoengineering, including geothermal development, deep mining, and nuclear waste geological disposal, high temperature significantly affects the mineral properties of rocks, thereby changing their porous and mechanical characteristics. This paper experimentally studied the changes in mineral composition, pore structure, and mechanical characteristics of pyroxene granite heated to high temperature (from 25 °C to 1200 °C). The results concluded that (1) the high-temperature effect can be roughly identified as three stages: 25–500 °C, 500–800 °C, 800–1200 °C. (2) Below 500 °C, the maximum diffracted intensities of the essential minerals are comparatively stable and the porous and mechanical characteristics of granite samples change slightly, mainly due to mineral dehydration and uncoordinated thermal expansion; additionally, the failure mechanism of granite is brittle. (3) In 500–800 °C, the diffraction angles of the minerals become wider, pyroxene and quartz undergo phase transitions, and the difference in thermal expansion among minerals reaches a peak; the rock porosity increases rapidly by 1.95 times, and the newly created pores caused by high heat treatment are mainly medium ones with radii between 1 μm and 10 μm; the P-wave velocity and the elastic modulus decrease by 62.5% and 34.6%, respectively, and the peak strain increases greatly by 105.7%, indicating the failure mode changes from brittle to quasi-brittle. (4) In 800–1200 °C, illite and quartz react chemically to produce mullite and the crystal state of the minerals deteriorate dramatically; the porous and mechanical parameters of granite samples all change significantly and the P-wave, the uniaxial compressive strength (UCS), and the elastic modulus decrease by 81.30%, 81.20%, and 92.52%, while the rock porosity and the shear-slip strain increase by 4.10 times and 11.37 times, respectively; the failure mechanism of granite samples transforms from quasi-brittle to plastic, which also was confirmed with scanning electron microscopy (SEM).

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“…At present, there are several [13][14][15][16][17] pilot plants for underground coal gasification combined with gas clean-up in China.…”

Section: Introductionmentioning

confidence: 99%

Semi-technical underground coal gasification (UCG) using the shaft method in Experimental Mine “Barbara”

Wiatowski

Stańczyk

Świądrowski

et al. 2012

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Semi‐industrial tests on enhanced underground coal gasification at Zhong‐Liang‐Shan coal mine

Cited by 36 publications

References 5 publications

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

Semi-technical underground coal gasification (UCG) using the shaft method in Experimental Mine “Barbara”

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