Mechanical specific energy consumption

Another benefit of high-speed SSE is the reduction in energy consumption. Rieg [108,109] reports the following mechanical specific energy consumption. 

Rauwendaal [97] proposed two new scale-up methods that result in constant mechanical specific energy consumption and high throughput rates. The first one keeps the specific surface area constant. This scale-up should work well for high values of... 

By careful process monitoring we can often detect the effects of wear. The process parameters that are affected by wear are meit temperature, output, and motor ioad. As wear progresses, the quality of the extruded product tends to deteriorate. This may manifest itself as discoloration, streaks, discolored specks, holes, etc. ft is very important to monitor the specific energy consumption (SEC) and specific extruder throughput (SET) because changes in these parameters often correiate with wear. SEC is the ratio of motor power divided by the throughput, ft is the mechanical power consumed per unit mass of plastic. The SEC tends to correiate with the melt temperature. The SEC is normally expressed in kWh/kg. A typicai vaiue of the SEC is 0.25 kWh/hr for extrusion of polyoiefins. 

Approximately 30% of the energy used in U.S. chemical plants and petroleum refineries is for distillation, and it accounts for nearly 3% of the total U.S. annual energy consumption. The energy usage associated with some specific distillation products is shown in Table III. The cost of energy for distillation can be reduced by using waste heat such as is available from quench water in ethylene plants, for example, or exhaust steam from mechanical drivers such as compressors. 

Electron-ion recombination is a highly exothermic process. Therefore, the process should have a specific channel of accumulation of the eneigy released during the neutralization of a positive ion and an electron. Most of these channels of recombination energy consumption are related, either to dissociation of molecules or to three-body collisions or to radiation, which determines the following three major groups of mechanisms of electron-ion recombination. 

The specific mechanical energy consumption (SMEC) is obtained by dividing the power consumption by the mass flow rate (throughput) ... 

When the throughput is expressed in kg/hr, the units of SMEC become kW-hr/kg. In scale-up it is often desirable to keep the specific mechanical energy consumption constant. 

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