Key Operating Parameters (key + operating_parameter)

Distribution by Scientific Domains

Selected Abstracts

Supercritical water oxidation of quinoline in a continuous plug flow reactor,part 2: kinetics

Lisete DS Pinto
Abstract The results of a detailed investigation into the kinetics of quinoline oxidation in supercritical water are presented. The novel kinetic data presented were obtained in a continuously operated, plug flow reactor where parameters such as temperature, pressure, residence time and stoichiometric ratio of oxidant to quinoline were investigated and detailed in the companion paper (Pinto LDS, Freitas dos Santos LMF, Al-Duri B and Santos RCD, Supercritical water oxidation of quinoline in a continuous plug flow reactor,part 1: effect of key operating parameters. J Chem Technol Biotechnol). An induction time was experimentally observed, ranging from 1.5 to 3.5 s, with longer times observed in experiments carried out at lower temperatures. A pseudo-first-order rate expression with respect to quinoline concentration (with oxygen excess) was first adopted and the activation energy of 234 kJ mol,1 and a pre-exponential factor of 2.1 1014 s,1 were estimated. Furthermore, an integral power rate model expression was established, attributing a reaction order for quinoline as 1 and for oxygen as 0.36. An activation energy and pre-exponential factor for this model were determined as 224 kJ mol,1 and 3.68 1014 M,0.36 s,1, respectively. A global rate expression was then regressed for the quinoline reaction rate from the complete set of data. The resulting activation energy was 226 19 kJ mol,1 and the pre-exponential factor was 2.7 1013 2 M,0.1 s,1. The reaction orders for quinoline and oxygen were 0.8 0.1 and 0.3 0.1, respectively. It was shown that the least-squares regression method provided the best-fit model for experimental results investigated in this study. Copyright 2006 Society of Chemical Industry [source]

A Systematic Approach for Scale-Down Model Development and Characterization of Commercial Cell Culture Processes

Feng Li
The objective of process characterization is to demonstrate robustness of manufacturing processes by understanding the relationship between key operating parameters and final performance. Technical information from the characterization study is important for subsequent process validation, and this has become a regulatory expectation in recent years. Since performing the study at the manufacturing scale is not practically feasible, development of scale-down models that represent the performance of the commercial process is essential to achieve reliable process characterization. In this study, we describe a systematic approach to develop a bioreactor scale-down model and to characterize a cell culture process for recombinant protein production in CHO cells. First, a scale-down model using 2-L bioreactors was developed on the basis of the 2000-L commercial scale process. Profiles of cell growth, productivity, product quality, culture environments (pH, DO, pCO2), and level of metabolites (glucose, glutamine, lactate, ammonia) were compared between the two scales to qualify the scale-down model. The key operating parameters were then characterized in single-parameter ranging studies and an interaction study using this scale-down model. Appropriate operation ranges and acceptance criteria for certain key parameters were determined to ensure the success of process validation and the process performance consistency. The process worst-case condition was also identified through the interaction study. [source]

Supercritical CO2 Extraction of Essential Oil from Algerian Rosemary (Rosmarinus officinalis,L.)

A. Zermane
Abstract The present study presents experimental results concerning the supercritical CO2 extraction of essential oil from Algerian rosemary leaves. The effects of key operating parameters such as pressure, temperature, particle size and CO2 mass flow rate on the extraction yield were investigated. The obtained yields were in the range of 0.95,3.52,g oil/g dry rosemary, and the best value was observed at a pressure of 22,MPa, a temperature of 40,C, a flow rate of 7,g/min, and a particle size of 1,mm. The performance of the local rosemary used was assessed by comparison of the obtained yields with values reported in the literature for essential oils derived from different rosemary sources. The GC and the GC-MS analyses showed that the major compound detected in the essential oil was camphor, at 48.89,wt,%. [source]

Applying a Thermodynamic Model to the Non-Stoichiometric Precipitation of Barium Sulfate

L. Vicum
Abstract Thermodynamic models for aqueous Ba2+ -SO42, -Na+ -Cl, -solutions are compared in their accuracy to predict ion activities in saturated and supersaturated solutions. The Pitzer and the Bromley model are employed, taking into account ion pair formation of barium sulfate. Such models are then used to describe particle nucleation and growth, and finally they are imbedded in a mechanistic mixing-precipitation model for a single feed semibatch process. The effect of the key operating parameters on the mean particle size is analyzed through simulations. The results are compared with previous experimental data, thus highlighting the significance of a proper choice of the thermodynamic model. [source]