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Practical Operation (practical + operation)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Monitoring of Machining Processes Using Sensor Equipped Tools,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Ekkard Brinksmeier
A different to conventional monitoring systems sensor equipped tools give the possibility to gain information about the process status directly from the contact zone between tool and component to be machined. For example this can be realized by the integration of small temperature sensors into grinding wheels. The transmitting of the process data is performed by a telemetric unit attached to the grinding wheel's core. In this paper, the development of a new thin film thermocouple sensor concept is described. The unique feature of this sensor is the continuous contacting of the thermocouple through the grinding process inherent wear which leads to smearing of the thermoelectric layers and thus forming the measuring junction of a thermocouple. The system was used in OD grinding processes aiming to detect grinding burn and process instabilities. By reducing the volume of the sensors a fast response and high time resolution can be obtained. By this way, observance of the key parameters of the practical operation as closely as possible to the cutting area is enabled and so observance of process efficiency and tool status independent from workpiece machining conditions can be realized. All sensors used are thermocouples of type K, a combination of Chromel (NiCr) and Alumel (NiAlMnSi) material. The maximum temperature to be measured by this sensor is about 1350,°C, which ensures the applicability in the grinding process. Telemetry components to amplify and send the thermovoltage signals are adjusted to this type of thermocouple. The ability of the set-up to detect thermal influences was demonstrated in grinding processes with a continuously increasing specific material removal rate. The approach serves to measure temperatures between fast sliding surfaces in harsh environments (fluids, high pressure, heat), similar to the grinding process. Therefore their application is not limited to tools but also applicable for other rotating components such as bearings, gears and shafts in powertrains. [source]

Analysis and control of heteroazeotropic batch distillation

AICHE JOURNAL, Issue 4 2005
S. Skouras
Abstract The separation of close-boiling and azeotropic mixtures by heterogeneous azeotropic distillation is addressed in batch columns. Both a common rectifier and a multivessel batch column are considered. Theoretical and graphical analyses of the process are presented for both column configurations and different separation strategies are presented. A simple control scheme is proposed for the practical operation of the columns, the implementation of different separation strategies and the realization of the final results. Dynamic simulations for mixtures classified under Serafimov's topological classes 2.0-2b and 3.1-2 verify the theoretical findings. The results show that heteroazeotropic batch distillation exhibits substantial flexibility. The column profile can be totally restored during the process and lie in regions different from those of the initial feed. The still path can cross distillation boundaries and the still product does not have to be the stable node of the feed region. Such results cannot be obtained by homogeneous azeotropic batch distillation. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source]

Carrier effects on oxygen mass transfer behavior in a moving-bed biofilm reactor

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009
Jie Ying Jing
Abstract This study investigates the carrier effects on the oxygen mass transfer behavior of a gas,liquid biofilm surface, and aims to provide evidence for parameter optimization in the practical operation of a moving-bed biofilm reactor (MBBR) during the coking-plant wastewater process. By using the dynamic oxygen dissolution method, the volumetric oxygen mass transfer coefficient KLa was measured by varying the suspended carrier stuffing rate and the intensity of aeration. Within the range of fluidizable flow rate, the efficiency of oxygen mass transfer increased with suspended carrier stuffing rate, and KLa reached its peak value when the stuffing rate was 40%. KLa has an increasing trend with an increase of the aeration intensity, but high aeration intensity was not favorable for reactor operation. Better oxygen mass transfer effect and higher oxygen transfer efficiency could be achieved when the aeration intensity was 0.3 m3 h,1 and the suspended carrier stuffing rate was 30,50%. The possible mechanisms that can account for carrier effects on oxygen mass transfer are the changes in the gas,liquid interfacial area. The ammonia nitrogen removal performance of the coking-plant wastewater in MBBR was satisfied by using the above-suggested conditions. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Lipase-Catalyzed Acyl Exchange of Soybean Phosphatidylcholine in n -Hexane: A Critical Evaluation of Both Acyl Incorporation and Product Recovery

BIOTECHNOLOGY PROGRESS, Issue 2 2005
Anders F. Vikbjerg
Lipase-catalyzed acidolysis was examined for the production of structured phospholipids in a hexane system. In a practical operation of the reaction system, the formation of lyso-phospholipids from hydrolysis is often a serious problem, as demonstrated from previous studies. A clear elucidation of the issue and optimization of the system are essential for the practical applications in reality. The effects of enzyme dosage, reaction temperature, solvent amount, reaction time, and substrate ratio were optimized in terms of the acyl incorporation, which led to the products, and lyso-phospholipids formed by hydrolysis, which led to the low yields. The biocatalyst used was the commercial immobilized lipase Lipozyme TL IM and substrates used were phosphatidylcholine (PC) from soybean and caprylic acid. A response surface design was used to evaluate the influence of selected parameters and their relationships on the incorporation of caprylic acid and the corresponding recovery of PC. Incorporation of fatty acids increased with increasing enzyme dosage, reaction temperature, solvent amount, reaction time, and substrate ratio. Enzyme dosage had the most significant effect on the incorporation, followed by reaction time, reaction temperature, solvent amount, and substrate ratio. However the parameters had also a negative influence on the PC recovery. Solvent amount had the most negative effect on recovery, followed by enzyme dosage, temperature, and reaction time. Individually substrate ratio had no significant effect on the PC recovery. Interactions were observed between different parameters. On the basis of the models, the reaction was optimized for the maximum incorporation and maximum PC recovery. With all of the considerations, the optimal conditions are recommended as enzyme dosage 29%, reaction time 50 h, temperature 54 °C, substrate ratio 15 mol/mol caprylic acid/PC, and 5 mL of hexane per 3 g substrate. No additional water is necessary. Under these conditions, an incorporation of caprylic acid up to 46% and recovery of PC up to 60% can be obtained from the prediction. The prediction was confirmed from the verification experiments. [source]