A computational mass transfer model is proposed for predicting the concentration profile and Murphree efficiency of sieve tray distillation column. The proposed model is based on using modified c＇2 -εc＇ two equatio...A computational mass transfer model is proposed for predicting the concentration profile and Murphree efficiency of sieve tray distillation column. The proposed model is based on using modified c＇2 -εc＇ two equations formulation for closing the differential turbulent mass transfer equation with improvement by considering the vapor injected from the sieve hole to be three dimensional. The predicted concentration distributions by using proposed model were checked by experimental work conducted on a sieve tray simulator of 1.2 meters in diameter for desorbing the dissolved oxygen in the feed water by blowing air. The model predictions were confirmed by the experimental measurement. The validation of the proposed model was further tested by comparing the simulated result with the performance of an industrial scale sieve tray distillation column reported by Kunesh et al. for the stripping of toluene from its water solution. The predicted outlet concentration of each tray and the Murphree tray efficiencies under different operating conditions were in agreement with the published data. The simulated turbulent mass transfer diffusivity on each tray was within the range of the experimental result in the same sieve column reported by Cai et al. In addition, the prediction of the influence of sieve tray structure on the tray efficiency by using the proposed model was demonstrated.展开更多
Dense-medium cyclones have been used for beneficiation of fine particles of coal. In this study, the usability of cyclones in the beneficiation of tailings of a coal preparation plant was investigated. For this purpos...Dense-medium cyclones have been used for beneficiation of fine particles of coal. In this study, the usability of cyclones in the beneficiation of tailings of a coal preparation plant was investigated. For this purpose, separation tests were conducted using spiral concentrator and heavy medium cyclones with the specific weight of medium 1.3-1.8 （g/cm^3） on different grading fractions of tailing in an industrial scale （the weight of tail sample was five tons）. Spiral concentrator was utilized to beneficiate particles smaller than 1 mm. In order to evaluate the efficiency of cyclones, sink and float experiments using a specific weight of 1.3, 1.5, 1.7 and 1.9 g/cm^3, were conducted on a pilot scale. Based on the obtained results, the recovery of floated materials in cyclones with the specific weight of 1.40, 1.47 and 1.55 g/cm^3 are 17.75%, 33.80%, and 50%, respectively. Also, the cut point （Pso）, which is the relative density at which particles report equally to the both products are 1.40, 1.67 and 1.86 g/cm^3. The probable errors of separation for defined specific weights for cyclones are 0.080, 0.085 and 0.030, respectively. Also, the coefficients of variation was calculated to be 0.20, 0.12 and 0.03. Finally, it could be said that the performance of a cyclone with a heavy medium of 1.40 g/cm^3 specific weight is desirable compared with other specific weights.展开更多
A new analytical method using Back-Propagation （BP） artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is estab...A new analytical method using Back-Propagation （BP） artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is established. By condition experiment, the optimum analytical conditions for calcium, magnesium and Arsenazo （Ⅲ） color reactions are obtained. Levenberg- Marquart （L-M） algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2 （nodes）. The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of kt take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%, respectively. The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water, 103.2% and 96.6% in the Yellow River water （Lijin district of Shandong Province）, and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao. It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions. The comparative experiments do not show any obvious differ- ence between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium. This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca^2＋ and Mg^2＋ in tap water and natural water.展开更多
The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those...The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those of the current industrial specifications. The results show that the optimized value K s approaches the one of those famous flip-flow screens in the world. Some new findings on geometric and kinematics parameters are useful for improving the flip-flow screens with a low K s value, which is helpful in developing clean coal technology.展开更多
Suspended particulate matter （SPM） levels in ambient air were monitored at Mandi Gobindgarh, an industrial town of Punjab, India located on the National Highway-1 during November 2001 to March 2002 covering spring a...Suspended particulate matter （SPM） levels in ambient air were monitored at Mandi Gobindgarh, an industrial town of Punjab, India located on the National Highway-1 during November 2001 to March 2002 covering spring and winter seasons to check the variation of SPM and its constituents in the town. The maximum levels of SPM varied between 594 μg/m^3 to 620 μg/m^3 at selected monitoring sites while the minimum levels varied between 209μg/m^3 to 220 μg/m^3. These values were observed always above the National Ambient Air Quality Standards （NAAQS） set by the State regulatory body. Major sources of SPM were identified as the industrial activity and traffic plying on the national highway. Collected SPM samples were further analyzed for the ignitable matter as loss on ignition （LOI） and organic tarry matter （OTM） content. Ignitable component of the SPM constituted about 45% and tarry matter in the ambient air was about 12%. Effects of meteorological parameters like temperature, wind direction and wind speed on SPM levels are discussed.展开更多
基金Supported by the National lqatural Science Foundation of China （20736005）.
文摘A computational mass transfer model is proposed for predicting the concentration profile and Murphree efficiency of sieve tray distillation column. The proposed model is based on using modified c＇2 -εc＇ two equations formulation for closing the differential turbulent mass transfer equation with improvement by considering the vapor injected from the sieve hole to be three dimensional. The predicted concentration distributions by using proposed model were checked by experimental work conducted on a sieve tray simulator of 1.2 meters in diameter for desorbing the dissolved oxygen in the feed water by blowing air. The model predictions were confirmed by the experimental measurement. The validation of the proposed model was further tested by comparing the simulated result with the performance of an industrial scale sieve tray distillation column reported by Kunesh et al. for the stripping of toluene from its water solution. The predicted outlet concentration of each tray and the Murphree tray efficiencies under different operating conditions were in agreement with the published data. The simulated turbulent mass transfer diffusivity on each tray was within the range of the experimental result in the same sieve column reported by Cai et al. In addition, the prediction of the influence of sieve tray structure on the tray efficiency by using the proposed model was demonstrated.
文摘Dense-medium cyclones have been used for beneficiation of fine particles of coal. In this study, the usability of cyclones in the beneficiation of tailings of a coal preparation plant was investigated. For this purpose, separation tests were conducted using spiral concentrator and heavy medium cyclones with the specific weight of medium 1.3-1.8 （g/cm^3） on different grading fractions of tailing in an industrial scale （the weight of tail sample was five tons）. Spiral concentrator was utilized to beneficiate particles smaller than 1 mm. In order to evaluate the efficiency of cyclones, sink and float experiments using a specific weight of 1.3, 1.5, 1.7 and 1.9 g/cm^3, were conducted on a pilot scale. Based on the obtained results, the recovery of floated materials in cyclones with the specific weight of 1.40, 1.47 and 1.55 g/cm^3 are 17.75%, 33.80%, and 50%, respectively. Also, the cut point （Pso）, which is the relative density at which particles report equally to the both products are 1.40, 1.67 and 1.86 g/cm^3. The probable errors of separation for defined specific weights for cyclones are 0.080, 0.085 and 0.030, respectively. Also, the coefficients of variation was calculated to be 0.20, 0.12 and 0.03. Finally, it could be said that the performance of a cyclone with a heavy medium of 1.40 g/cm^3 specific weight is desirable compared with other specific weights.
文摘A new analytical method using Back-Propagation （BP） artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is established. By condition experiment, the optimum analytical conditions for calcium, magnesium and Arsenazo （Ⅲ） color reactions are obtained. Levenberg- Marquart （L-M） algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2 （nodes）. The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of kt take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%, respectively. The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water, 103.2% and 96.6% in the Yellow River water （Lijin district of Shandong Province）, and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao. It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions. The comparative experiments do not show any obvious differ- ence between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium. This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca^2＋ and Mg^2＋ in tap water and natural water.
文摘The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those of the current industrial specifications. The results show that the optimized value K s approaches the one of those famous flip-flow screens in the world. Some new findings on geometric and kinematics parameters are useful for improving the flip-flow screens with a low K s value, which is helpful in developing clean coal technology.
文摘Suspended particulate matter （SPM） levels in ambient air were monitored at Mandi Gobindgarh, an industrial town of Punjab, India located on the National Highway-1 during November 2001 to March 2002 covering spring and winter seasons to check the variation of SPM and its constituents in the town. The maximum levels of SPM varied between 594 μg/m^3 to 620 μg/m^3 at selected monitoring sites while the minimum levels varied between 209μg/m^3 to 220 μg/m^3. These values were observed always above the National Ambient Air Quality Standards （NAAQS） set by the State regulatory body. Major sources of SPM were identified as the industrial activity and traffic plying on the national highway. Collected SPM samples were further analyzed for the ignitable matter as loss on ignition （LOI） and organic tarry matter （OTM） content. Ignitable component of the SPM constituted about 45% and tarry matter in the ambient air was about 12%. Effects of meteorological parameters like temperature, wind direction and wind speed on SPM levels are discussed.
