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Li X.-S.,East China University of Science and Technology | Li X.-S.,Qinghai Salt Lake Industry Group Co. | Sun Z.,East China University of Science and Technology | Song X.-F.,East China University of Science and Technology | And 2 more authors.
Huadong Ligong Daxue Xuebao/Journal of East China University of Science and Technology | Year: 2012

Numerical simulation is an effective way to study the hydrodynamics for the industrial scale equipments. In this paper, a mathematical model combined with k-ε turbulent equation and multiple reference frame (MFR) was developed to predict the flow field in the crystallizer. The accuracy of the numerical method was validated by comparison with the experimental data of the flow field in a laboratory scale stirred tank measured by partical image velocity (PIV) instrument. Based on the simulation results for the flow field in the crystallizer, the effects of the impeller location, operating parameters on the flow field in the crystallizer were studied in details. It was found that the optimal parameters for the design and operation of the crystallizer were: the installed height of impeller was 1000 mm, the column length of the crystallizer was 2000 mm, and the economic rotational speed was 70-80 r/min. Source


Zhang M.-H.,East China University of Science and Technology | Li X.-S.,East China University of Science and Technology | Li X.-S.,Qinghai Salt Lake Industry Group Co. | Luo Y.,East China University of Science and Technology | And 2 more authors.
Huadong Ligong Daxue Xuebao /Journal of East China University of Science and Technology | Year: 2010

Stirred tanks are widely used in many industrial processes. In this paper, the mixing process of industry crystallizer was simulated three-dimensionally by computational fluid dynamics (CFD). The multi-reference frame (MRF) and standard κ-ε turbulent model were used in the simulation to analyze the effect of the propeller structure, rotational speed and the distance of impeller location on the flow field in the crystallizer. The simulation results show that the velocity distributes mainly on the area in the interior draft tube and between the interior and exterior draft tube. Therefore, according to the notable difference of velocity at different areas, the crystallizer can be divided into approximately two zones based on the different effects in the flow processes of crystallization: the cycle zone with high velocity speed inside the draft tube and the sedimentation zone with low velocity speed outside the draft tube. Through comparison of velocity contour between cycle zone and sedimentation zone, propeller is proved to be more suitable than others, and the best distance of impeller location in the system is from 3.5 m to 5.7 m. The uniform velocity rate of fluid flow upward at the sedimentation zone engendered through the appropriate rotational speed can bring out the small crystals and is favorable for large particle size products. The detailed flow field in the stirred tank and different operation parameters can provide theoretical guidance to optimize the structure and operation parameter in the industrial scale. The industrial results show that the product particle size has been significantly increased, and the proportion of particles more than 0. 2 mm increases from less than 50% to more than 90%. Natural gas consumption for drying products is decreased from 22 m3/t to 15 m3/t. The energy is remarkable saved. Source


Song X.,East China University of Science and Technology | Gu Q.,East China University of Science and Technology | Wang J.,East China University of Science and Technology | Li H.,Qinghai Salt Lake Industry Group Co. | And 2 more authors.
Huagong Xuebao/CIESC Journal | Year: 2011

The adsorption of alkylmorpholine (DMP) on NaCl and KCl crystals was studied with the density functional theory (GGA-PW91) using computer simulation, where NaCl(100) with F color center and KCl(100) with O2 - defect. The charges of ions on NaCl(100) are changed to positive by F color center, while the charges of ions on KCl(100) are changed to negative by O2 -. The adsorption energy of DMP on Na-top is -157.00 kJ · mol-1 and that on KCl(100) with O2 - is -59.14 kJ · mol-1. Therefore, DMP can be adsorbed on both NaCl and KCl, and the interaction between NaCl and DMP is stronger. The flotation experiments on the overflow potash ore containing alkylmorpholine indicate that the flotation recovery for NaCl is high, while the recovery of KCl is low. This result reflects different adsorption characteristics of DMP on surfaces of NaCl and KCl, which corroborates the result of computer simulation. © All Rights Reserved. Source


Gu Q.-D.,East China University of Science and Technology | Song X.-F.,East China University of Science and Technology | Wang J.,East China University of Science and Technology | Li C.-B.,Qinghai Salt Lake Industry Group Co. | And 3 more authors.
Gao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities | Year: 2010

The overflow potash ore is the deposit of flotation overflow, which is discharged from the production of KCl by the reverse-flotation and cold-crystallization process. KCl and NaCl crystals are the main components of the ore, and KCl content in it is about 70%. Flotation technique was adopted to separate the KCl from NaCl in the overflow ore, and a flotation tube with a cooling jacket was used to make the flotation could take place at certain temperature. The core sheet in the tube was used as the bubble producer. Since an amount of alkymorpholine exists in the overflow ore, no other chemicals are needed to be added in the overflow ore for its further flotation process. During the flotation of the overflow ore, the NaCl is concentrated in the foams and the KCl crystal is remained in the liquid and then precipitated. Through the experiments, the effects of percent solid pulp and temperature on the flotation efficiency were investigated. Based on the experimental results, it was found that, by further flotation at 20°C and keeping the variation of percent solid pulp in the range of 21% to 38%, the crude product of overflow ore flotation is consisted of above 92% KCl, and the KCl recovery is up to 85%. While when the percent solid pulp was kept at 25% and the variation of the temperature was controlled at the range of 0.0~20.0°C, the crude product is consisted of 92% KCl, and the KCl recovery of 70%~86% was obtained. After washing the crude product, the fine product consisting of above 97% KCl could be achieved. Source

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