The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform

Roohollah Bagheri - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of the effect of Reflux Rate during suspension polymerization on particle properties of pvc resin
    Industrial & Engineering Chemistry Research, 2010
    Co-Authors: Nasrin Etesami, Mohsen Nasr Esfahany, Roohollah Bagheri
    Abstract:

    The particle morphological properties of poly(vinyl chloride) produced by suspension polymerization in a pilot-scale reactor under different Reflux Rates have been investigated. It was found that the monomer conversion decreased with increasing Reflux Rate. It was also observed that the cold plasticizer absorption (CPA) increased with Reflux Rate, whereas the bulk density (BD) and K value of the resin decreased. SEM micrographs showed that PVC resin with a rougher particle surface, more sepaRate aggregates, and smaller primary particles was prepared at higher Reflux Rates. The particle size distribution determined by laser size analysis showed that the standard deviation of the particle size distribution and the mean particle size did not change significantly with Reflux Rate.

Huang Guo-qian - One of the best experts on this subject based on the ideXlab platform.

  • Simulation and optimization of divided wall column for separating thionyl chloride
    2014
    Co-Authors: Huang Guo-qian
    Abstract:

    The indirect sequence as a conventional process was simulated by using Aspen Plus software for the separation of thionyl chloride. And divided wall column( DWC) was proposed as an innovative process to sepaRate thionyl chloride. Furthermore,the effect of feed stage,side draw stage,the ratio of Reflux Rate to feed and distribution ratio on the product purity and reboiler duty was discussed. The optimum operating conditions determined are as follows: the feed stage is the 6th tray of pre-fractionator,the side draw stage is the 55th tray of main column,the ratio of Reflux Rate to feed is 4. 45,the liquid distribution ratio is 1. 60,and the vapor distribution ratio is 1. 98. The results show that DWC opeRated in optimal conditions can save condenser duty and reboiler duty by 34. 62% and 34. 64% respectively,compared with the conventional indirect sequence. Meanwhile,DWC can save capital cost by 17. 27% from the calculating result of CAPCOST software. So DWC for the separation of thionyl chloride is an energy saving and efficient separation technology.

  • Redistribution reactive distillation process for treating dichlorosilane
    2014
    Co-Authors: Huang Guo-qian
    Abstract:

    A reactive distillation process for treating dichlorosilane via redistribution was proposed. The bottom product containing tetrachloride was externally recycled back into reactive zone. The anti-redistribution reactive distillation process was developed in industry and simulated by Aspen Plus. The reaction kinetics and chemical equilibrium were taken into account in the equilibrium stage model. The simulation results agree well with the industrial test data. It indicates that the dichlorosilane can be efficiently converted to trichlorosilane in the process, with the conversion of dichlorosilane reaching 98. 6% and the purity of trichlorosilane reaching 91. 6%. On that basis,the effects of feed stage location,liquid holdup,the mole ratio of feed material and Reflux Rate were investigated. The values of the process variables were optimized and determined. The economic potential for the process was estimated.

Jun Jiang - One of the best experts on this subject based on the ideXlab platform.

  • control of a process with no Reflux Rate in heterogeneous extractive distillation hed
    Separation and Purification Technology, 2020
    Co-Authors: Jun Jiang
    Abstract:

    Abstract In this work, a process with no Reflux Rate (R) of distillate product in heterogeneous extractive distillation (HED) for the separation of close boiling compounds is proposed. The effects of pressure in HED and flowRate of solvent on controllability and economic performance are investigated. Close loop sensitivity tests show that an increase in flowRate of solvent can enhance the controllability but increases the annual total cost (TAC). Simulation shows that higher pressure in HED leads to lower flowRate ratio of solvent (EG) to feed. A lower pressure is preferred for economic index, but has worse controllability. There is trade-off between controllability and economic performance. The interaction between units is analyzed theoretically based on mass balance principle. The analysis can help further design of control structure. A basic control structure (CS1) based on modified alternative process with increased solvent flowRate is proposed first. Then an improved control structure (CS2) based on CS1 is proposed to reject the flowRate disturbance and address the interaction between units. Dual temperatures are applied in the recovery column (C2). The temperatures of two stages are controlled by the ratio of Reflux Rate to feed (R/F) and reboiler duty in C2, respectively. Pressure-compensated temperature control is applied to compensate temperature in the presence of flowRate disturbance. Dynamic responses show the improved control structure can handle ± 10% feed flowRate and ± 20% composition disturbances.

Steven S. Raman - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic contrast-enhanced (DCE) MR imaging: the role of qualitative and quantitative parameters for evaluating prostate tumors stratified by Gleason score and PI-RADS v2
    Abdominal Radiology, 2019
    Co-Authors: Sohrab Afshari Mirak, Amirhossein Mohammadian Bajgiran, Kyunghyun Sung, Nazanin H. Asvadi, Daniela Markovic, Ely R. Felker, David Lu, Anthony Sisk, Robert E. Reiter, Steven S. Raman
    Abstract:

    Purpose To investigate the role of qualitative and quantitative DCE-MRI parameters in prostate cancer (PCa) stratified by whole-mount histopathology (WMHP) Gleason score (GS) and PI-RADSv2. Methods This retrospective study included 323 PCa tumors in 254 men, who underwent 3T MRI prior to prostatectomy, 7/2009-12/2016. Qualitative DCE curve types included type 1 (progressive), type 2 (plateau) and type 3 (washout). Quantitative DCE-MRI pharmacokinetic (PK) parameters included K ^trans (influx volume transfer coefficient), K _ep (efflux Reflux Rate constant) and iAUC (initial area under the curve). DCE-MRI features of true positive lesions were evaluated for overall, index, transition zone (TZ) and peripheral zone (PZ), based on GS grade (low = 6, high > 6) and PI-RADSv2 score using SPSSv24. Results There were 57 (17.6%) low-grade and 266 (82.4%) high-grade PCa lesions. PI-RADSv2 3, 4 and 5 included 106, 120 and 97 lesions, respectively. 251 (77.7%) and 72 (22.3%) lesions were located in PZ and TZ, respectively. High-grade lesions had significantly higher proportion of Type 3 curves compared to low-grade lesions in overall (70.3% vs. 54.4%) and TZ (73.5% vs. 43.5%). As PI-RADSv2 increased, the proportion of type 3 curve significantly increased for overall (80.4–51.9%), index (80.4–54.7%) and PZ (78.7–52.1%) lesions. Among PK parameters, K ^trans (0.43 vs 0.32) and iAUC (8.99 vs 6.9) for overall PCa, K ^trans (0.43 vs 0.31) and iAUC (9 vs 6.67) for PZ PCa, and iAUC (8.94 vs 7.42) for index PCa were significantly higher for high-grade versus low-grade lesions. Also, K ^trans (0.51–0.34), K _ep (1.75–1.29) and iAUC (9.79–7.6) for overall PCa, K ^trans (0.53–0.32), K _ep (1.81–1.26) and iAUC (9.83–7.34) for PZ PCa; and K _ep (1.79–1.17) and iAUC (11.3–8.45) for index PCa increased significantly with a higher PI-RADSv2 score. Conclusions The results of study show the possible utility of qualitative and quantitative DCE-MRI parameters for assessment of PCa GS and PI-RADSv2 categorization.

Francisco López - One of the best experts on this subject based on the ideXlab platform.

  • Spirit Distillation StRategies for Aroma Improvement Using Variable Internal Column Reflux
    Food and Bioprocess Technology, 2016
    Co-Authors: Juan José Rodríguez-bencomo, Ignacio Orriols, José Ricardo Pérez-correa, Francisco López
    Abstract:

    The production of spirits by distillation of wine, fruit wines, and grape pomace is normally carried out using classic copper Charentais alembic or batch distillation columns. An alternative to these classic systems, however, is a rectification packed column equipped with an internal partial condenser which allows for easy control of the internal Reflux by manipulating the flow of cooling water of the partial condenser. This paper outlines an experimental study which explores the ability of variable Reflux distillation policies in packed columns to tailor the chemical composition of the distillate. The results showed that a high Reflux Rate at the beginning of the distillation is a good option to reduce the impact of unpleasant compounds in the heart cut. Using this stRategy, 40 % less head compounds were recovered in the heart cut, reducing their sensorial impact by 70 %. In addition, 50 % less acetic acid was recovered in the heart cuts. High Reflux Rates during the heart cut distillation reduce the concentration of higher alcohols; nevertheless, this stRategy must be applied for longer periods than those used in our study to significantly alter the composition of the heart cuts.