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The study of the energy accumulation and rate of release in hard coal under dynamic, static, and coupled dynamic-static loading and its failure mode is of significance when studying the mechanism underpinning coal mine dynamic disasters such as rock burst, coal, and gas outburst. In this paper, four experimental methods (uniaxial compression, Brazi...
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The surrounding rock of roadways in underground coal mines will lose its stability or even collapse under gas explosions, especially roadways surrounded by coals. The dynamic mechanical properties of coals were tested in order to investigate the dynamic response of coals under gas explosions. The static mechanical properties of coals were also test...
Citations
... By the end of June 2022, the growth rate of raw coal output was up to 15.3% as shown in Figure 1a [1]. Coal gasification and coking industry consume large amount of coal [2][3][4], leading to production of coal gasification slag (CGS) and coking wastewater (CW) in abundance. Numerous pollutants including ammonia, cyanide, phenols, other organic compounds, and toxic components are present in CW [5][6][7]. ...
Powder adsorbent made by coal gasification slag (CGS) was used to adsorb pollutants from coking wastewater (CW). This study initially focused on the removal efficiency of volatile phenol, NH3–N, and chemical oxygen demand (COD) from CW. The removal rate of volatile phenol increased from 48.90% to 70.50% after acid precipitation of CW by 4.0 mL reagent of sulfuric acid (3.0 M) and optimization of adsorption process by central composite design-response surface methodology with optimized conditions. Volume ratio of liquid and solid adsorbent (V
L/S) and pH were the significant factors in the adsorption process. Batch experiment improved the volatile phenol, NH3–N, and COD removal rate to 85.1%, 41.6%, and 77.3%, respectively. Multi-grade batch process in grade 3 made a further promotion of pollutants removal rate as 98.5%, 73.6%, and 80.5%, respectively. Scanning electron microscope-energy dispersive spectrum and Fourier-transform infrared spectrometer were used to confirm the adsorption effect. CGS-based adsorbent for CW treatment has potential advantages due to the features of good adsorption performance and low cost.
... e results showed that the peak value of energy dissipation rate is associated with stress drop during coal deformation, as well as to the uniaxial compressive strength. Hao et al. [30] analyzed the energy accumulation, energy rate of release, and failure modes of hard coal under dynamic, static, and coupled dynamic-static loading. e results showed that the degree of destruction and fragmentation of coal samples increases with the increase of prepeak energy accumulation. ...
Dynamic crushing characteristics of coals are closely related with energy absorption and release of coals under certain strain rate. Hence, it is necessary to investigate energy dissipation laws of coal crushing under the impact loads with different strain rates. Based on the dynamic and static mechanical tests, crushing energy, total absorption energy, total releasable elastic latent energy, and relations between fractal feature of fragments, mean particle diameter and energy during crushing behaviors of outburst coal and nonoutburst coal were investigated. According to research results, crushing energy, total absorption energy, and releasable elastic latent energy of outburst coal and nonoutburst coal are related with strain rate, and they present exponential growths with the increase of the strain rate. However, the energy dissipation rate (ratio of crushing energy and incident energy) was basically constant at about 10%∼20%, that is, energy dissipation rate is a variable unrelated with strain rate. There is a good logarithmic relationship between the dynamic compressive strength of coals and the absorption energy density and elastic latent energy density, and dynamic comprehensive strength of coals has important impacts on energy absorption. The fractal features of coal fragments were obvious under dynamic impacts. The higher fractal dimension of fragment and the smaller mean particle diameter of experimental fragments bring the greater energy needed.
Carbon dioxide (CO2) emission reduction has become an urgent topic to be studied and solved with the in-depth understanding of global warming and frequent occurrence of extreme climate. At present, the application of chemical looping technology in coal gasification to produce high purity synthesis gas is an important way to achieve CO2 emission reduction, ensure energy security, and promote ecological civilization. In this paper, a new fusion research method combining multi-scale modeling and experimental testing is adopted to comprehensively optimize the coal chemical looping gasification (CCLG) process, aiming at ruducing CO2 emissions in the synthesis gas production of CCLG. In order to investigate the effect of main reaction conditions on CCLG process, the pyrolysis and gasification experiments of Meihuajing coal are carried out in a tubular furnace reactor with Fe2O3 and CuO as oxygen carriers respectively. Subsequently, the multi-scale simulation of CCLG process including molecular dynamics (MD) and computational fluid dynamics (CFD) simulations is performed to validate the experimental results and supplement important reaction kinetics data. Both of multi-scale modeling and experimental testing suggest that the optimum pyrolysis temperature range, gasification temperature range, char/oxygen carrier mass ratio (C/O), and steam flow are below 900 ℃, 900–950 ℃, 1:1.5, and 0.15 g/min respectively, providing an effective guidance for the optimal design of practical CCLG pilot plant.
