Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification. This is an important source of polycyclic aromatic hydrocarbon （PAH） emission in China. Pyrolysis in a coal seam was simula...Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification. This is an important source of polycyclic aromatic hydrocarbon （PAH） emission in China. Pyrolysis in a coal seam was simulated in a tubular furnace. The 16 US Environmental Protection Agency priority controlled PAHs were analyzed by HPLC. The effects of temperature, heating rate, pyrolysis atmosphere, and coal size were investigated. The results indicate that the 3-ring PAHs AcP and AcPy are the main species in the pyrolysis gas. The 2-ring NaP and the 4-ring Pyr are also of concern. Increasing temperature caused the total PAH yield to go through a minimum. The lowest value was obtained at the temperature of 600℃. Higher heating rates promote PAH formation, especially formation of the lower molecular weight PAHs. The typical heating rate in a coal seam, 5 ℃/min, results in intermediate yields of PAHs. The total PAHs yield in an atmosphere of N2 is about 1.81 times that seen without added N2, which indicates that an air flow through the coal seam accelerates the formation of PAHs. An increase in coal particle size reduces the total PAHs emission but promotes the formation of 5- and f-ring PAHs.展开更多
The ＂torque rich＂ is known as a phenomenon that makes reduction of ship speed, overload for main engine and higher fuel consumption of ship, even can cause some major problems for a ship propulsion system. In Vietna...The ＂torque rich＂ is known as a phenomenon that makes reduction of ship speed, overload for main engine and higher fuel consumption of ship, even can cause some major problems for a ship propulsion system. In Vietnam, according to investigated results, almost ships of country merchant fleet are facing with ship speed decrease, fuel consumption increase due to the torque rich, consequently the average ship operation cost is increasing from 15% to 25%, even higher in some cases and the environment is badly impacted. To comply with the international requirements and national legislation regarding to ＂using efficiently energy and environment protection＂, Vietnamese shipping companies must combat with the torque rich problem as crucial reason making downgrade in ship operation. The article shows a potential method to reduce the torque rich phenomena by modifying propeller which has been successfully applied for a real ship in Vietnam.展开更多
基金provided by the National Natural Science Foundation of China (No. 50876112)the Fundamental Research Funds for the Central Universities (No. 2009QH13)the International Scientific and Technological Cooperation Project(No. 2010DFR60610)
文摘Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification. This is an important source of polycyclic aromatic hydrocarbon （PAH） emission in China. Pyrolysis in a coal seam was simulated in a tubular furnace. The 16 US Environmental Protection Agency priority controlled PAHs were analyzed by HPLC. The effects of temperature, heating rate, pyrolysis atmosphere, and coal size were investigated. The results indicate that the 3-ring PAHs AcP and AcPy are the main species in the pyrolysis gas. The 2-ring NaP and the 4-ring Pyr are also of concern. Increasing temperature caused the total PAH yield to go through a minimum. The lowest value was obtained at the temperature of 600℃. Higher heating rates promote PAH formation, especially formation of the lower molecular weight PAHs. The typical heating rate in a coal seam, 5 ℃/min, results in intermediate yields of PAHs. The total PAHs yield in an atmosphere of N2 is about 1.81 times that seen without added N2, which indicates that an air flow through the coal seam accelerates the formation of PAHs. An increase in coal particle size reduces the total PAHs emission but promotes the formation of 5- and f-ring PAHs.
文摘The ＂torque rich＂ is known as a phenomenon that makes reduction of ship speed, overload for main engine and higher fuel consumption of ship, even can cause some major problems for a ship propulsion system. In Vietnam, according to investigated results, almost ships of country merchant fleet are facing with ship speed decrease, fuel consumption increase due to the torque rich, consequently the average ship operation cost is increasing from 15% to 25%, even higher in some cases and the environment is badly impacted. To comply with the international requirements and national legislation regarding to ＂using efficiently energy and environment protection＂, Vietnamese shipping companies must combat with the torque rich problem as crucial reason making downgrade in ship operation. The article shows a potential method to reduce the torque rich phenomena by modifying propeller which has been successfully applied for a real ship in Vietnam.
