Specific power consumption

Biichs J, Zoels B (1999) Evaluation of the Maximiun Specific Power Consumption in Shaking Bioreactors, Proceedings of 3th International Symposium on Mixing in Industrial Processes (ISMlP-3) 19-22 Sept 1999 Japan... 

The principal advantage of the technology is the low cell voltage and therefore low specific power consumption. 

In a first approximation the specific power consumption per unit volume dN/dV of the moist powder in a mixer is equal to ... 

Type of Reactor or Mass T ransfer System Type of Hydrodynamic Behavior Specific Power Consumption (kW m"3)... 

Power consumption aspects have been critically analyzed to reveal that vibration effects in molding heads may reduce specific power consumption in extrusion machines, while simultaneously improving the quality of manufactured products. 

The electrode separation was 2 cm the potential difference necessary for spark over gas was 13—16 kV. By varying the residence time of the gas in the reactor from 30 to 600 s a product containing 15—17% C2H2 by volume was obtained at relatively low temperatures. Increasing the input rate and decreasing the specific power consumption increased the amount of C2H2 formed, but decreased the C2H2 concentration in the product. Copper electrodes were reported to produce the least deposition of carbon black and cuprene. 

After the cascade improvement and cascade operating programs planned 6y U.S. DOE have been completed, their power consumption will be increased to 7,380,000 kW and their separative capacity to 27,700,000 kg SWU/year, equivalent to a specific power consumption of 0.266 kW/(kg SWU/year). 

Rao, D.B.N., "The Effect of Crystallinity of Limestone and Particle Size Distribution of Kiln Feed on the Dust Emission, Specific Power Consumption and Clinker Quality," Proceedings of the 10th International Conference on Cement Microscopy, International Cement Microscopy Association, San Antonio, Texas, 1988, pp. 152-176. 

Figure 3.21. Typical plot of empirical engineering correlation between G L transfer coefficient Lja and specific power consumption P/V as a function of superficial gas velocity % q. The shaded areas (A for pure water and B for ionic solutions) represent the range of validity of correlations.

Figure 3.22. Comparison of G L reactors of different constructions in a plot of specific interfacial area a versus specific power consumption P/F stirred tanks (ST), bubble columns (BC), jet nozzles (JN), packed beds (PB), venturi washers (V) and plug flow-jet nozzles (PFJN). (Adapted from Nagel et al., 1972).

Energy consumption is measured in kilowatt-hours per ton of product, the product being either chlorine or caustic. Most operators and technology suppliers choose caustic as the basis for measurement. This choice reflects the practical difficulties of measuring chlorine production accurately and taking into account system losses that end up principally as hypochlorite or HCl. Another comphcation is the dependence of anolyte current efficiency on the amount of acid or alkali present in the feed brine (Section 7.5.6.1). The caustic current efficiency, for all practical purposes, depends only on the membrane efficiency. It becomes more convenient and usually more accurate to measure the production of caustic. One need only measure the amount of solution produced and analyze its caustic content. Again for convenience and accuracy, and assuming the use of membrane cells, it is best to measure the output of cell liquor. This separates the electrolyzer and evaporator test runs. These measurements make it possible to calculate the anode current efficiency from analytical data and hence, to calculate chlorine production and specific power consumption. 

The viscous dissipation is a specific power consumption, i.e., power per unit volume. In S.I. units it is expressed in Watts per cubic meter [W/m ]. The heat fiux away from the polymer melt is determined by the heat fiux from the melt to the barrel and screw. If the screw is neutral the heat fiux to the screw is usually small and can be assumed to be negligible. If screw cooling is used, this assumption will not be correct. The heat fiux (heat flow per unit cross-sectional area) for cooling the polymer melt is determined by Fourier s law of conductive heat transport ... 

As a rule, the two rolls are driven separately, each through a V-belt drive. The specific power consumption is in the range of 0.2 to 0.3kWh/t. 

In general it can be stated that with feed material which may cause difficulties on account of low friction due to its specific material properties and/or granulometric composition it is possible to achieve distinct improvements in mill throughput, operational behaviour and specific power consumption by the addition of hard coarse particles. Improvements can similarly be obtained when dealing with feed material that tends to become solidly compacted on the grinding ring because of its moisture content and composition, e. g., too high a proportion of clay... 

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