Horsepower distribution

Motor-driven, multistage reciprocating compressors have reportedly been the most popular choice for aeroderivatives. Motor-driven, oil-fiooded screw compressors are also used in some cases. High horsepower, multistage centrifugal compressors, similar to those used at many pipeline compressor stations, may be required for the newer heavy-duty units if the distribution pipeline pressure is insufficient (see Pipelines). Gas turbines have more stringent fuel-gas specifications in terms of cleanliness than do gas-fired boilers. Thus oil- and water-knockout systems, coalescing filters, and fine-mesh filters are used. 

Performance, 387 Ground Area vs. Height, 391 Pressure Losses, 393 Fan Horsepower for Mechanical Draft Tower, 392 Water Rates and Distribution, 393 Blow-Down and Continuation Build-Up, 394 Example 915 Determining Approximate Blow-Down for Cooling Tower, 395 Pre-... 

Figure 4.14 is the current waveform of an ASD of smaller horsepower. This drive contains line side inductors which, along with the higher inductance of the motor, produce a current waveform with less distortion. Table 4.6 provides the harmonic frequency distribution for this ASD. 

The term apparent viscosity refers to a viscosity that has been back-calculated from impeller torque or horsepower. A true-viscosity reading should be measured at a fixed and known shear rate. The effective shear rate developed by a mixing impeller is really a distribution of different shear rates. This distribution is probably most closely related to the shear between the helix blade and the tank... 

Bucket elevators. The bucket elevators lift catalyst, at 900-1000°F., about 200 ft. Each elevator consists of two chains with a continuous line of alloy-steel buckets loosely supported between them (217). The upper shaft is fixed in position but the bottom shaft can move to offset thermal expansion and wear of the chain. Chain speeds are 90 to 125 ft./minute at catalyst-circulation rates of 100 to 150 tons/hour. Power requirement is 60 to 80 horsepower (241). Differential band brakes protect against reverse rotation in case of a power failure. Sprockets with renewable teeth were used at first (217), but a traction-wheel drive was later substituted because wear is more evenly distributed and life is longer (241). Repair techniques have been developed for extending chain life (316). Graphite is used to lubricate the chains (239). The upper shaft and main bearings are water-cooled and the bearings are lubricated with oil. 

For steam boilers, fuels are natural gas and blast furnace gas. A large number of small burners (about 30 hp. each) is used for the former. Burners are thoroughly distributed. As with fuel oil, they may be directed either slightly downward toward the rear or may face from the bridge wall toward the front. The combustion space should be large. The air supply is drawn in around the gas jet. High eflSciency is easily possible. For blast furnace gas, use a furnace space of 2 cu. ft. per rated horsepower, 0.8 sq. in. of gas passage area per horsepower and 2 in. blast (based on 6 to 8 in. pressure in main). Provision must be made for removal of dust. With all gas burners, the gas and air supply should be separately controllable. 

Example.— Required the net operating cost per ton of a 400-ft. conveyor handling 60,000 tons of fine coal during 1,200 operating hours in the year. The conveyor to elevate the coal 24 ft. and distribute it by means of an automatic tripper over a bunker 60 ft. long. Power delivered at the conveyor drive commands a value of 3 cts. per horsepower. 

The viscosity of milks of lime depends on the solids content, the particle size distribution of the slaked lime, the temperature of the milk and the degree of maturing. It may be determined, for the purposes of selecting a pump, by using an instrument such as the Brookfield viscometer. The friction loss when pumping milks of lime is generally allowed for by increasing the horsepower of the pump by about 10 % [23.1]. 

This credo, as promnlgated by the then Association of Roller and Silent Chain Manufactnrers (ARSCM) soon led to a series of projects to build and operate chain test equipment in the laboratory. From those projects were developed the horsepower curves covering all basic sizes of standard roller drive chains. These were inclnded in a hardbound chain design manual, published by ARSCM in 1955, and entitled Design Manual, Roller and Silent Chain Drives. That edition and its softbound snccessors, pnblished in 1968 and 1975, have seen nearly 30,000 copies distributed by the association. 

The advantages of forced draft air cooler are 1) tube bundle is easier to be removed for service, 2) fan and motor are easier to be installed and accessible for maintenance, 3) easier for warm air recirculation ftireold climate service, 4) use slightly less horsepower, since air to fan is cooler. Its disadvantages are 1) poorer air distribution over tube bundle, 2) tOip of tube bundle is exposed to ixmbient weather, 3) bottom of tube bundle is hard to reach for cleaning, 4) more chance for hot exit air recirciilation, due to lower exit air velocity and no stack, 5) less cooling in case fans are failed due to tow natural draft. 

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