The exact measurement of the fill level is the key and basic problem for automatic control and optimized operation of the coal pulverizing system. Because the ball mill pulverizing system is non-linearity, long time d...The exact measurement of the fill level is the key and basic problem for automatic control and optimized operation of the coal pulverizing system. Because the ball mill pulverizing system is non-linearity, long time delay and time-varying, the reliable and effective method for measuring the fill level was lacked at present. In order to reduce the influence by various factors on measuring the fill level and improve the measuring accuracy of the fill level, a novel characteristic variable is proposed. A set of wireless transmission device was designed to record vibration signals, and an accelerometer with high accuracy and large measuring range was mounted directly on the mill shell to pick up the vibration signals from the mill shell. A series of data acquisition experiments under various ball load and water content of coal conditions were conducted in an industrial mill to investigate the relationship between the fill level and the angular position of the maximum vibration point of the mill shell through the analysis of the vibration signals. The analytical result of test data clearly show that the angular position of the maximum vibration point on the mill shell decreases as the fill level increases. At the same time, comparing with the traditional characteristic variable, the feature variable of the fill level proposed in this paper is not subject to the effect of the ball load and water content of coal, which provides a new solution and reliable basis for the accurate measurement of the fill level.展开更多
In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuou...In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling （DMM） instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy （EDX） and X-ray diffraction （XRD） of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-α-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TLA1 as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51005047, 51075070)Production and Research Joint Innovation Fund of Jiangsu Province (Grant No. BY2009152)New Doctor Teacher Foundation of Southeast University of China (Grant No. 9202000024)
文摘The exact measurement of the fill level is the key and basic problem for automatic control and optimized operation of the coal pulverizing system. Because the ball mill pulverizing system is non-linearity, long time delay and time-varying, the reliable and effective method for measuring the fill level was lacked at present. In order to reduce the influence by various factors on measuring the fill level and improve the measuring accuracy of the fill level, a novel characteristic variable is proposed. A set of wireless transmission device was designed to record vibration signals, and an accelerometer with high accuracy and large measuring range was mounted directly on the mill shell to pick up the vibration signals from the mill shell. A series of data acquisition experiments under various ball load and water content of coal conditions were conducted in an industrial mill to investigate the relationship between the fill level and the angular position of the maximum vibration point of the mill shell through the analysis of the vibration signals. The analytical result of test data clearly show that the angular position of the maximum vibration point on the mill shell decreases as the fill level increases. At the same time, comparing with the traditional characteristic variable, the feature variable of the fill level proposed in this paper is not subject to the effect of the ball load and water content of coal, which provides a new solution and reliable basis for the accurate measurement of the fill level.
文摘In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling （DMM） instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy （EDX） and X-ray diffraction （XRD） of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-α-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TLA1 as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.
