Power Consumption Of Agitators Research Articles

Elucidation of the Molecular Mechanism of Wet Granulation for Pharmaceutical Standard Formulations in a High-Speed Shear Mixer Using Near-Infrared Spectroscopy.

The granulation process of pharmaceutical standard formulation in a high-speed shear wet granulation (HSWG) was measured by in-line near-infrared spectroscopy (NIRS) and agitation power consumption (APC) methods. The F-1, F-2, and F-3 formulations (500 g) contained 96% w/w α-lactose monohydrate (LA), potato starch (PS), and a LA:PS = 7:3 mixture, respectively, and all the formulations contained 4% w/w hydroxypropyl cellulose. While adding purified water at 10 mL/min, the sample powder was mixed. The calibration models to measure the amount of binding water (Wa) and APC of the HSWG formulations were established based on NIRS of the samples measured for 60 min by partial least-squares regression analysis (PLS). Molecular interaction related to APC between the particle surface and binding liquor was analyzed based on NIRS. The predicted values of Wa and APC for all formulations were superimposed with the measured values on a straight line, respectively. The regression vector (RV) of the calibration model for Wa indicated the chemical information of all the water in the samples. In contrast, the RV for APC suggested that APC changes in the processes are related to powder aggregation because of surface tension of binding water between particles.

Analysis of granulation mechanism in a high-shear wet granulation method using near-infrared spectroscopy and stirring power consumption

The dynamic granulation process of high-speed shear wet granulation (HSWG) was measured by in-line near-infrared spectroscopy (NIRS) and agitation power consumption (APC) methods. Molecular interactions between powder particles and the binding liquid were analyzed based on both NIRS and APC data by multivariable regression analysis. The granulated sample used glass beads (d50 = 46 μm) with or without hydroxypropyl cellulose, and the binder solution used purified water. The HSWG granulator (2-L volume) with APC device and NIRS was used, and the agitator was rotated at 600 min−1 and the chopper at 2000 min−1 with glass beads to be granulated being 920 g (0.6 L), and a total of 360 mL of purified water was added at 10 mL/min. In order to establish calibration models to predict APC and amount of binding water of the granular formulations, NIRS spectra of the granular samples were recorded every 10 s for 40 min. The calibration models to predict moisture content and APC were constructed based on the corrected NIRS spectral data by partial least-squares regression (PLSR) analysis. The relationships between actual and predicted values for moisture content and APC produced a straight line, respectively. The regression vector (RV) of the PLS model to predict the water content showed the presence of free water between the bead powder particles. On the other hand, the RV for the APC showed the presence of bound water between the particles.

Reducing the agitation power consumption in anaerobic digestion of corn straw by adjusting the rheological properties

Abstract Agitation power consumption (P) in the anaerobic digestion of biogas plants is a major part of the electric energy consumption. To reduce P by adjusting the rheological properties, in this work, the rheological properties of corn straw slurry were studied systematically with the consideration of the effects of TS, temperature and particle sizes. The P was calculated based on the rheological behaviour of corn straw slurry. The investigation shows that the thermophilic digestion is effective only for the slurry with a relatively high TS. The size-reduction is more effective at higher TS compared to the option of increasing temperature in order to improve the agitation power efficiency, and the value of P can be reduced by up to 48.11 %. Since the size-reduction can also increase the methane yield, the adjustment of particle sizes is a promising option to save P, especially at higher TS.

Adjusting the rheological properties of corn-straw slurry to reduce the agitation power consumption in anaerobic digestion

Agitation power consumption (P) in the anaerobic digestion of biogas plants is a major consumer of electric energy. To reduce P by adjusting the rheological properties, in this work, the rheological properties of the corn-straw slurry were studied systematically considering the effects of TS, temperature and particle-size, and P was calculated based on the rheological behavior of the corn-straw slurry. The investigation shows that the corn-straw slurry is a non-Newtonian fluid and exhibit shear-thinning behavior, and the rheological properties can be well described with the power law model. The size-reduction is more effective compared to the option of temperature-increase to improve the agitation power efficiency, and the value of P can be reduced by up to 48.11%. Since the size-reduction can also increase the methane yield, the reduction of the particle-size is a promising option to save P, especially at relatively high TSs and for the thermophilic AD process.

Application of gas-inducing reactor to obtain high oxygen dissolution in aeration process

The application of gas-inducing reactor to obtain high oxygen dissolution has been investigated at various operation conditions including agitation speed, temperature (20–40°C), pressure (1.0–1.2 atm) and working liquid levels. Correlations regarding onset speed, agitation power consumption, gas holdup and oxygen mass transfer coefficient were established from experimental data. Onset speed can be accurately predicted with modified Froude number. The agitation power consumptions before and after onset speed is a function of Froude number and working liquid level. Gas holdup is an important factor influencing the mass transfer of oxygen after onset speed. In the study of mass transfer of oxygen ( T=20°C, P=1 atm), the highest dissolved oxygen concentration is as high as 39.34–39.92 mg L −1. The value of k L a is within 0.511–1.792 min −1. The k L a is not affected by the oxygen gas pressure (1.0–1.2 atm). However, k L a increases with increasing temperature. The gas-inducing reactor of this study has higher k L a than the other type of gas-inducing reactor under the same unit volume power consumption. The pure oxygen utilization rate of this system can be as high as 100%.

Scale-up method for the power consumption of agitators in the creeping flow regime

Scale-up method for the power consumption of agitators in the creeping flow regime

Scale-up method for power consumption of agitators in the creeping flow regime

A method enabling the determination of power consumption of industrial agitators in a non-Newtonian fluid on the basis of measurements on a model device is presented. The applicability of the method is limited to creeping flows in the vessel. The suggested method was experimentally confirmed and is suitable mainly for mixing of highly viscous non-Newtonian fluids.

Hydrocarbon fermentations using Candida lipolytica. II. A model for cell growth kinetics.

AbstractA mechanistic model is presented for the growth kinetics of a yeast grown by submerged aerobic fermentation using a liquid hydrocarbon as sole carbon source. The model is based on the assumption that cell growth is governed by the extent of probable cell attachment at the hydrocarbon oil‐droplet surfaces in a four‐phase dispersion. An analytical expression has been developed for the model. It is shown that for the case of relatively small oil droplets, the model predicts the present and previous experimental data for growth of yeasts (Candida species) in n‐alkane systems. The model is further examined for maximal growth in terms of substrate dilution rate and agitation power consumption for a continuous fermentation process.