Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central p...Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist^ersion in the bath.展开更多
Dual fluidized bed gasifiers （DFBG） are effective in producing nitrogen-free syngas from biomass. How- ever, to improve the gasifier performance, pressure drops and solid fractions within the DFBG system need to be ...Dual fluidized bed gasifiers （DFBG） are effective in producing nitrogen-free syngas from biomass. How- ever, to improve the gasifier performance, pressure drops and solid fractions within the DFBG system need to be controlled. In this study, the effects of varying the fluidizing velocity in the fast fluidized bed （FFB） on the pressure drops and the solid fractions in the system were investigated in a 100 kW DFBG and in a dual fluidized bed cold model （DFCM）. Based on the experimental results, empirical correlations were developed to predict the height-averaged solid fraction in the bottom section of the FFB. Accuracy and advantages of the correlations were analyzed. The correlation is useful for design and modeling of the DFBG systems where the height-averaged solid fraction is required to be determined.展开更多
The effects of superficial gas velocity, catalyst loading, liquid properties and internal fitting on gas holdup of air/water, air/paraffin oil and air/catalyst/paraffin oil were investigated in a 0 2 m diameter, 4 2 m...The effects of superficial gas velocity, catalyst loading, liquid properties and internal fitting on gas holdup of air/water, air/paraffin oil and air/catalyst/paraffin oil were investigated in a 0 2 m diameter, 4 2 m height slurry bubble column reactor operating with methanol synthesis copper-based catalyst and methanol dehydration catalyst. The experimental data showed that gas holdup increased with superficial gas velocity no matter whether there was a heat exchanger. However, no matter whether there was a heat exchanger, gas holdup decreased with the increase of catalyst loading. The existence of heat exchanger favored the increase of gas holdup. The gas holdup in the air-water system was slightly higher than in the air-paraffin system. Empirical correlations for gas holdup data were proposed.展开更多
基金Item Sponsored by National Natural Science Foundation of China(50974035,51074047)National High Technology Research and Development Program(863 Program)of China(2010AA03A405,2012AA062303)Innovation Team Project of Provincial Science and Technology of Liaoning Province of China(LT2010034)
文摘Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist^ersion in the bath.
基金funded by the Ministry of Business,Innovation and Employment,New Zealand
文摘Dual fluidized bed gasifiers （DFBG） are effective in producing nitrogen-free syngas from biomass. How- ever, to improve the gasifier performance, pressure drops and solid fractions within the DFBG system need to be controlled. In this study, the effects of varying the fluidizing velocity in the fast fluidized bed （FFB） on the pressure drops and the solid fractions in the system were investigated in a 100 kW DFBG and in a dual fluidized bed cold model （DFCM）. Based on the experimental results, empirical correlations were developed to predict the height-averaged solid fraction in the bottom section of the FFB. Accuracy and advantages of the correlations were analyzed. The correlation is useful for design and modeling of the DFBG systems where the height-averaged solid fraction is required to be determined.
文摘The effects of superficial gas velocity, catalyst loading, liquid properties and internal fitting on gas holdup of air/water, air/paraffin oil and air/catalyst/paraffin oil were investigated in a 0 2 m diameter, 4 2 m height slurry bubble column reactor operating with methanol synthesis copper-based catalyst and methanol dehydration catalyst. The experimental data showed that gas holdup increased with superficial gas velocity no matter whether there was a heat exchanger. However, no matter whether there was a heat exchanger, gas holdup decreased with the increase of catalyst loading. The existence of heat exchanger favored the increase of gas holdup. The gas holdup in the air-water system was slightly higher than in the air-paraffin system. Empirical correlations for gas holdup data were proposed.
