Power cost

CAPITAL AND OPERATIONAL COST ANALYSIS 9.1. Minimizing Power Costs 

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Cooling water costs tend to be low relative to the value of both fuel and electricity. The cost of cooling duty provided by cooling water is on the order of 1 percent that of the cost of power. For example, if power costs 0.07 kW h, then cooling water will typically cost 0.07 X 0.01/3600 = 0.19 x 10 kJ or 0.19 GJ L... 

The abrasive industry is highly competitive and many small companies worldwide successfully compete by specializing in a particular segment of the business, eg, disk wheels, mounted points, and mbber wheels. Costs in the fused abrasive industry are primarily in materials and electric power. Thus manufacturers seek out plant sites having the lowest power costs. Costs for coated abrasive manufacturers are capital and labor intensive and they seek out sources of low cost labor. 

The collection of particles larger than 1—2 p.m in Hquid ejector venturis has been discussed (285). High pressure water induces the flow of gas, but power costs for Hquid pumping can be high because motive efficiency of jet ejectors is usually less than 10%. Improvements (286) to Hquid injectors allow capture of submicrometer particles by using a superheated hot (200°C) water jet at pressures of 6,900—27,600 kPa (1000—4000 psi) which flashes as it issues from the nozzle. For 99% coUection, hot water rate varies from 0.4 kg/1000 m for 1-p.m particles to 0.6 kg/1000 m for 0.3-p.m particles. 

Most of the voltage savings in the air cathode electrolyzer results from the change in the cathode reaction and a reduction in the solution ohmic drop as a result of the absence of the hydrogen bubble gas void fraction in the catholyte. The air cathode electrolyzer operates at 2.1 V at 3 kA/m or approximately 1450 d-c kW-h per ton of NaOH. The air cathode technology has been demonstrated in commercial sized equipment at Occidental Chemical s Muscle Shoals, Alabama plant. However, it is not presentiy being practiced because the technology is too expensive to commercialize at power costs of 20 to 30 mils (1 mil = 0.1 /kW). 

Price. The 1993 U.S. price for fluorine in cylinders was 109/kg for 2.2 kg and 260/kg for 0.7 kg cylinders. The price in large volumes is determined by (/) the price of hydrofluoric acid (2) power costs, ca 4.5 kWh electricity is required for each kilogram of fluorine produced (J) labor costs (4) costs to maintain and rebuild cells and (5) amortization of fixed capital. Fluorine production is highly capital intense. In addition, purification, compression, packaging, and distribution in cylinders increase the cost significantly. 

As of the mid-1990s all commercial phosphoms is manufactured at a few sites around the world. Significant production occurs in Idaho and Montana in the United States, in the Netherlands, in Kazakstan, and in China smaller production occurs in Prance, Russia, and India. A large amount of furnace capacity has been shut down worldwide because of cost pressure from electric power costs, phosphate derived from purified wet acid, and detergent phosphate bans legislated in the Western World. However, as of late 1995, additional production is stiU being brought on line in China. 

Optimum Pressure Drop. For most heat exchangers there is an optimum pressure drop. This results from the balance of capital costs against the pumping (or compression) costs. A common prejudice is that the power costs are trivial compared to the capital costs. The total cost curve is fairly flat within 50% of the optimum (see Fig. lb), but the incremental costs of power are roughly one third of those for capital on an aimualized basis. This simple relationship can be extremely useful in quick design checks. 

Operating-cost data for these units are meager. Power costs may be estimated by assuming 1 hpper cylinder for diameters of 1.2 to 1.8 m (4 to 6 ft). Data on labor and maintenance costs are also lacking. 

Number of effects versus steam, water, and pump power cost. 

Dielectric dryers have not as yet found a wide field of application. Their fundamental characteristic of generating heat within the solid indicates potentialities for diying massive geometrical objects such as wood, sponge-rubber shapes, and ceramics. Power costs may range to 10 times the fuel costs of conventional methods. 

Operating Costs Power cost for a continuous thickener is an almost insignificant item. For example, a unit thickener 60 m (200 ft) in diameter with a torque rating of 1.0 MN-m (8.8 Mlbf in) will normally require 12 kW (16 hp). The low power consumption is due to the very slow rotative speeds. Normally, a mechanism vi l be designed for a peripheral speed of about 9 m/min (0.5 ft/s), which corresponds to only 3 r/h for a 60-m (200-ft) unit. This low speed also means veiy low maintenance costs. Operating labor is low because little attention is normally required after initial operation has balanced the feed and underflow. If chemicals are required for flocculation, the chemical cost frequently dwarfs all other operating costs. 

The development of improved supports and drive mechanisms has allowed gyratory crushers to take over most large hard-ore and mineral-crushing applications. The largest expense of these units is in relining them. Operation is intermittent so power demand is high, but the total power cost is not great. 

Sulfur The riug-roUer mill can be used for the fine grinding of sulfur. Inert gases are supplied instead of hot air (see Properties of Sohds Safety for use of inert gas). Performance of a Raymond No. 5057 ring-roller mill is given in Table 20-34. The total cost might be 3 to 4 times the power cost and include labor, inert gas, maintenance, and fixed charges. 

These items are highly site specific. Power cost is low because the salinity removed by the selected plant is low. The quality of the feed water, its sahnity, turbidity, and concentration of problematic ionic and fouhng solutes, is a major variable in pretreatment and in conver-... 

A new concept is to use an on/oFf air supply cycle. During aeration, nitrates are produced. When the air is shut off, nitrates are reduced to nitrogen gas. This prevents acid buildup and removes nitrogen from the sludge. High power cost for aerobic digestion restricts the applica-bihty of this process. 

Includes water and power cost, maintenance cost, operating cost, capital and insurance costs. 

Ranking equipment and teehnology options for an intended applieation then beeomes a matter of seleeting those projeet options with the shortest paybaek period. So, for example, if we compare a baghouse versus an electrostatic filter for a dust control application, an overall payback period for each option can be determined based on the capital investment for each piece of equipment, operating, maintenance, power costs, and other factors. 

Centrifugation - Centrifugation has been demonstrated to be capable of thickening a variety of wastewater sludges. Centrifuges are a compact, simple, flexible, self-contained unit, and the capital cost is relatively low. They have the disadvantages of high maintenance and power costs and often a poor, solids-capture efficiency if chemicals are not used. 

This equation shows that the operating pressure drop is proportional to the square of the filtering velocity. For a fixed set of operating conditions, increasing filtering velocity to reduce the size of the collector will result in increases in pressure drop, fan power costs, and penetration and probably reduction in bag life. 

Because of quite poor color rendition and difficulty in safe disposal of expended lamps, low pressure sodium fixtures are less desirable than high pressure sodium fixtures and are seldom recommended for production facilities. High pressure sodium fixtures are particularly attractive for illuminating large open areas. At locations where power cost is low and where many fixtures are required due to equipment shadowing, mercury vapor fixtures often are preferred because of their lower initial cost, lower replacement lamp cost, and better color rendition. 

Power costs for fan and pump horsepower, approximate pump efficiency for water, and any special data peculiar to the economics of the installation. This will allow the manufacturer to select a tower giving consideration to the economic factors involved. 

Refrigerant temperatures greater than 32°F suggest the steam jet or lithium bromide absorption system. Between 30°F and —40°F, the ammonia-water absorption or a mechanical compression system is indicated. At less than —40°F, a mechanical compression is used, except in special desiccant situations. The economics of temperature level selection will depend on utility (steam, power) costs at the point of installation and the type of pay-out required, because in some tonnage ranges, the various systems are competitive based on first costs. 

Reduce motor current pulsations and power costs. 

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