Electrical power requirements

In equation 7.12, P is the impeller power, that is, the energy per unit time dissipated within the liquid. Clearly, the electrical power required to drive the motor will be greater than P on account of transmission losses in the gear box, motor, bearings, and so on. 

The electrical power required to drive a compressor (or pump) can be calculated from a knowledge of the motor efficiency ... 

The energy costs on a large site can be reduced if the electrical power required is generated on site and the exhaust steam from the turbines used for process heating. The overall... 

Under utilities should be included the costs for items that enter the plant but do not enter directly into the material formulation of the products or by-products. This includes coal, oil, gas, electricity, water, air, and inert gases. The amounts of cooling, process, and potable water should each be specified. Potable water is water that can be used for drinking and food preparation. It is usually purchased from a nearby municipality. The average electrical power required, peak power required, and demand power need to be calculated. Demand power is the number of kilowatts of energy that the utility company agrees to supply on an uninterrupted basis. A premium price is charged for this power. 

Table E11.4B lists information about the different levels of steam, and Table El 1.4C gives the demands on the system. To meet the electric power demand, electric power may be purchased from another producer with a minimum base of 12,000 kW. If the electric power required to meet the system demand is less than this base, the power that is not used will be charged at a penalty cost. Table El 1.4D gives the costs of fuel for the boiler and additional electric power to operate the utility system.

Liquid hydrogen requires extreme precautions in handling because of the low temperature. Fueling is usually done mechanically with a robot arm. Even in large, centralized liquefaction units, the electric power requirement is high with 12 to 15 kilowatt-hours (kWh) needed per kilogram of hydrogen liquefied. 

On the basis of Eq. (2), it is evident that the lower silver resistivity proportionally reduces the electrical power required to produce a given field. At the same time, it reduces the time constant RjL of the magnet which is an important factor in minimizing the final field-switching times. Section IV C discusses how the magnet time constant RjL and the power supply output voltage affect the maximum achievable slewing rate dBjdt. 

High moisture content in the soil may also increase the cost of barrier installation. The vendor estimates that barrier formation in soils with 36% moisture content will cost approximately 9% more than a typical free-down period in favorable soils (16% moisture content). These elevated costs are attributed to the increase in electrical power required to freeze the additional water present in the soil (D18426T, p. 3). 

The centrifugal nitration process is reasonably economic. However, it requires well instructed personnel, it is troublesome for the workmen, and its electric power requirements are high. 

Another photochemical oxidation system has been developed by Sun River Innovations, Ltd. According to the company, their SR2000 system combines air stripping, oxidation, ultraviolet light, hydroxyl destruction, and selfcleaning activated carbon in one small treatment unit. The flow rate and the electrical power required are shown in Table 7.10. 

Light flicker due to arc furnaces requires extra mention. Arc furnaces, commonly found in many industrial towns, typically use scrap metal as the starting point. An arc is struck in the metal by applying voltage to the batch from a specially constructed furnace transformer. The heat due to the arc melts the scrap metal, which is drawn out from the furnace to produce raw material for a variety of industrial facilities. Arc furnaces impose large electrical power requirements on the electrical system. 

The electrostatic separator shown in Fig. 4.2 is normally placed in stream 6, shown in Fig. 4.1. A heater should be installed upstream of this electrostatic treater to control temperature. Here heating temperatures should normally range from 100 to 200°F for light crudes 22°API and above. For heavier crudes, use higher temperatures, such as 250°F for a 14°API crude oil. Some heavier crudes, below 14°API, may require temperatures up to 300°F for adequate electrostatic dehydration. This temperature is to achieve a gravity difference between the crude oil and water of 0.001 or more. The electric power required by these electrogrids is normally 0.05 to 0.10 kVA/ft2. The ft2 area is the horizontal cross-section area in the electric grid section of the electrostatic dehydrator. 

The proposed flow sheet produces hydrogen at a pressure of 10 bar according to the chosen pressure of the electrolysis cell. Compared to the electrolysis of water, whose pressure of hydrogen product is about 1 bar, the power requirement to raise the pressure up to 10 bar is not negligible. The electric power requirement to do such work is about 9.8 kj/mole H2. With this output condition, the new heat requirement for VHTR-powered water electrolysis becomes 881 kj/mole H2 With a total equivalent heat requirement of 680 kj/mole H2, the proposed HyS process flow sheet compares favourably to VHTR-powered water electrolysis. 

Kruger, P. (2001), Electric Power Requirement for Large-scale Production of Hydrogen for the World Vehicle Fleet , International Journal of Hydrogen Energy, 26,1137-1147. 

To facilitate measurement and control of larger flow rates, the heat-transfer-type flowmeters can also be placed in a small bypass around a capillary element in the process pipe. The laminar flow element serves to ensure laminar flow and also acts as a restriction forcing a portion of the flow into the sensor tube. The small-size bypass serves to minimize the electric power requirement and to increase the speed of response, but it requires upstream filters to protect it against plugging. 

The treatment cost stems principally from the electrical power required to operate the systems. A major secondary expense is the cost of lamps. 

Auxilliary and support equipment, required to sustain the operation and not easily adapted to use in the explosive environment, was located in an equipment module (Figure 4) attached to the end of the shop and sufficiently isolated to preclude any hazard to operations conducted therein. The gasoline driven electric generator supporting total electric power requirement, a heat pump, air compressor and hydraulic pump are all located within this equipment module. A sectionized rod with self-contained hammer is provided and stored in the equipment module. This rod is driven into the ground at each work location and connected to the shop frame to insure electrical grounding and prevention of any buildup of static electricity that could produce a spark within the shop. 

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