Flower-like ZnO microstructures were successfully synthesized via a facile hydrothermal route without using any surfactants. The morphology of these microstructures can be easily controlled by adjusting the pH of the reaction solution. The possible growth mechanism of ZnO hierarchical microstructures was proposed based on the X-ray powder diffraction (XRD) and scanning electron microscope (SEM) results. The photocatalytic activity studies of ZnO nanocrystals demonstrated their excellent photocatalytic performance in degrading aqueous methylene blue (MB) under UV-A light irradiation. This higher photocatalytic activity of the ZnO nanoplates was mainly attributed to the exposed facets with the higher surface energy.
The potential in coal seams gas resources in Poland is estimated to be similar to known conventional reserves (about 150 bln s.cu.m) but present efficiency of utilization is much lower. Many coalmines utilize this gas for a small-scale heating and electricity generation, but global utilization efficiency is as low as 60%. In Poland, methane is recovered mainly for safety reasons from coalmines. This paper presents new possibilities for methane production from abandoned coalmines and from unmineable, deep coal seams. In the first case the gob gas ventholes can be drilled from the surface, in the second case multilateral wells technology can be employed. In the paper, the simulation models of mined and unmined coal seams are presented and discussed. The results are evaluated from both technical and economical point of view. Economical analysis showed positive NPV and IRR=10%. Two case studies presented in this paper show that both abandoned coalmines and unmineable coal seams could be effectively utilized for coalbed methane production using advanced drilling technologies. During the last decade many coalmines over the Europe have been abandoned for both economical and environmental reasons, others are in the terminal state of production. However, some of these mines still contain large resources of methane that could be used for the local purposes like heating or electricity generation. The case study of the Moszczenica coalmine in Poland, including computer simulation of the coal and methane production shows that gob gas can be successfully recovered using new wells drilled from the surface. Presently, the deep unmineable coal seams are often not utilized from economic reasons. The case study presented in this paper shows that they can be effectively utilized for coalbed methane production using advanced drilling technologies like multilateral wells.
The potential in coal seams gas resources in Poland is estimated to be similar to known conventional reserves (about 150 bln s.cu.m) but present efficiency of utilization is much lower. Many coalmines utilize this gas for a small-scale heating and electricity generation, but global utilization efficiency is as low as 60%. In Poland, methane is recovered mainly for safety reasons from coalmines. This paper presents new possibilities for methane production from abandoned coalmines and from unmineable, deep coal seams. In the first case the gob gas ventholes can be drilled from the surface, in the second case multilateral wells technology can be employed. In the paper, the simulation models of mined and unmined coal seams are presented and discussed. The results are evaluated from both technical and economical point of view. Economical analysis showed positive NPV and IRR=10%. Two case studies presented in this paper show that both abandoned coalmines and unmineable coal seams could be effectively utilized for coalbed methane production using advanced drilling technologies. During the last decade many coalmines over the Europe have been abandoned for both economical and environmental reasons, others are in the terminal state of production. However, some of these mines still contain large resources of methane that could be used for the local purposes like heating or electricity generation. The case study of the Moszczenica coalmine in Poland, including computer simulation of the coal and methane production shows that gob gas can be successfully recovered using new wells drilled from the surface. Presently, the deep unmineable coal seams are often not utilized from economic reasons. The case study presented in this paper shows that they can be effectively utilized for coalbed methane production using advanced drilling technologies like multilateral wells.
This paper presents an improved reservoir simulation approach to methane production in a longwall mining environment. The coal beds are naturally fractured systems with the gas adsorbed into the coai matrix. Fractures penetrating the coal matrix have limited storage capacity, but they play the role of a gas transportation system. The proposed simulation technique is based on the assumption that a mass of coal removed by mining transfers its gas to adjacent fractures. By using an ECLIPSE coai bed methane simulator, the pore volume of the matrix represents the coai volume of the simulation cell. Consequently, the exploitation of coal can be simulated by modifying the matrix pore volume over time. This paper presents theoretical backgrounds of this approach and investigates numerical effects. A case study of the Moszczenica coai mine in Poland, including computer simulations of methane production, is also reported to show that a long history of the methane and coal recovery can be reproduced using the proposed technique.
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