Pumping power, loss

Vacuum pumps Power loss no structural damage Nraie required 1 month to restore off-site power... 

Figure 10-123 shows a typical power consumption in thrust bearings as a function of unit speed. Tne total power loss is usually about 0.8-10 percent of the total rate power of the unit. New vector lube bearings reduce the horsepower loss by as much as 30 percent. In large vertical pumps, thrust bearings take not only the load caused by... 

As a power transmission medium, the fluid must flow easily through lines and component passages. Too much resistance to flow creates considerable power loss. The fluid also must be as incompressible as possible so that action is instantaneous when the pump is started or a valve shifts. 

None No flow -chlorination loop Pump failure. Loss of electric power to pump. No chlorine flow to tower basin. Low chlorine concentration in tower basin. Chlorination pump malfunction alarm. 1 ... 

In order to determine the total power (so-called shaft output) of the pump, mechanical power losses Ny (for example in the bearing seals) must be considered ... 

With 80% efficiency of the pump, total energy loss is 1.2x10 ft-lb /lb and the pumping power required is... 

In addition to the shaft power needed to raise the water heat transfer medium from the low to high loop pressure, additional compressor power is needed to overcome frictional pressure drop around the loop. The power associated with this loss has been compared with that of the high temperature process loop in the reference design. To understand the role of the different heat transport fluid -water in the alternate design versus helium in the reference design - the pumping power is expressed as a fraction of the pumping power per unit thermal power transported. This permits a consistent comparison between the two loops even if they differ in total thermal power transported. 

The pumping power for a water-based versus helium-based loop was calculated at the full power condition. The fluid properties in the respective loops were used to calculate the friction loss power per unit megawatt of thermal power transported for the water-based loop as a fraction of the same in the helium-based loop. The result derived in Vilim (2009) shows that the power in the water loop is insignificant to the power in the helium loop. In the helium loop the circulating power needed is about 7 MWe or 14 MWt out of a reactor thermal capacity of 600 MWt. Thus an advantage of a water-based loop is that the pumping power to overcome frictional losses is significantly less and results in an efficiency increase. 

Pulsed laser-Raman spectroscopy is an attractive candidate for chemical diagnostics of reactions of explosives which take place on a sub-microsecond time scale. Inverse Raman (IRS) or stimulated Raman loss (.1, ) and Raman Induced Kerr Effect (2) Spectroscopies (RIKES) are particularly attractive for singlepulse work on such reactions in condensed phases for the following reasons (1) simplicity of operation, only beam overlap is required (2) no non-resonant interference with the spontaneous spectrum (3) for IRS and some variations of RIKES, the intensity is linear in concentration, pump power, and cross-secti on. 

The liquid is put into the absorption tower by means of a nozzle at the top of the tower. The pressure just before the nozzle is 35 psig. Assume the pump for the liquid must supply power to lift the liquid to the top of the tower and compress the liquid to 35 psig. Use a 10 percent safety factor on the above pumping-power requirements to take care of the friction in the lines and other minor losses. 

What if a cooling tower has power loss to pumps or fans ... 

Once the pressure loss (or head loss) is known, the required pumping power to overcome the pressure loss is determined from... 

Consider the flow of oil at 20°C in a 30-cm-diameter pipeline at an average velocity of 2 m/s (Fig. 8-24). A 200-m long section of the horizontal pipeline passes through icy waters of a lake at 0°C. Measurements indicate that the surface temperature of the pipe Is very nearly 0°C. Disregarding the thermal resistance of the pipe material, determine (a) the temperature of the oil when the pipe leaves the lake, (b) the rate of heat transfer from the oil, and (c) the pumping power required to overcome the pressure losses and to maintain the flow of the oil in,the pipe. 

The ineversible pressure loss due to frictional effects and the required pumping power to overcome this loss for a volume flow rale of 1/are... 

Water at 15 C is heated by passing it through 2-cm-inlemal-diametcr thin-walled copper tubes. Heat is supplied to the water by steam that condenses outside the copper tubes at 120 C. If water is to be healed to 65°C at a rate of 0.2 kg/s, detennine (a) the length of the copper tube that needs to be used and (b) the pumping power required to nvercomc pressure losses. Assume the entire copper tube to be at the steam temperature ofI20 C. 

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