Selective pumping

Example 1 NPSH Calculation Suppose a selected pump requires a minimum NPSH of 16 ft (4.9 m) when pumping cold water What will he the NPSH limitation to pump propane at 55 F (12.8 C) with a vapor pressure of 100 psi Using the chart in Fig. 10-25, NPSH reduction for propane gives 9.5 ft (2.9 m). This is greater than one-half of cold water NPSH of 16 ft (4.9 m). The corrected NPSH is therefore 8 ft (2.2 m) or one-half of cold water NPSH. 

In the analysis of pumps, IPRDS failure data for 60 selected pumps at four nuclear power plants were statistically analyzed using FRAC. The data cover 23 functionally different pumps, respectively, for two BWRs. Catastrophic, degraded, and incipient failure severity categories were considered for both demand-related and time-dependent failures. 

For catastrophic demand-related pump failures, the variability is explained by the following factors listed in their order of importance system application, pump driver, operating mode, reactor type, pump type, and unidentified plant-specific influences. Quantitative failure rate adjustments are provided for the effects of these factors. In the case of catastrophic time-dependent pump failures, the failure rate variability is explained by three factors reactor type, pump driver, and unidentified plant-specific Influences. Point and confidence interval failure rate estimates are provided for each selected pump by considering the influential factors. Both types of estimates represent an improvement over the estimates computed exclusively from the data on each pump. The coded IPRDS data used in the analysis is provided in an appendix. A similar treatment applies to the valve data. 

From manufacturer s performance tables, select pump nearest to GPM and head requirements. 

Sources Younger, A.H., Ruiter, J.L. Selecting Pumps and Compressors, Chemkd Engineering, June 26, 1961, p. 117. 

Mo biological uptake and processing. As an essential trace nutrient. Mo uptake and incorporation into enzymes is tightly controlled at the cellular level via selective pumps and... 

Using vacuum condensers (see Section 2.15). These act as selective pumps and should be sized so that the downstream gas ballast pump will not receive more vapor than the amount corresponding to the appropriate vapor tolerance. 

When selecting pumps for any service, it is necessary to know the liquid to be handled, the total dynamic head, the suction and discharge heads, and, in most cases, the temperature, viscosity, vapor pressure, and specific gravity. In the chemical industry, the task of pump selection is frequently further complicated by the presence of... 

Fig. 1 displays a series of SFG spectra of CO/Pt(l 11) for selected pump-IR probe delays. In this work, we only present a general discussion of spectrum analysis. A more detailed report will be presented elsewhere. A red shift and broadening of the CO band (as already observed for CO/Pt(l 11) at a ps time scale [4], and for C0/Ru(0001 [2]), and variations of the spectral shape, are observed. This does not indicate an excitation of the internal stretch itself (there is no indication that v=l is populated). The spectral changes rather reflect the excitation of other modes which perturb the internal stretch through anharmonic coupling. Among the three possible modes, frustrated translation and frustrated rotation can be considered. The CO-Pt stretch is ignored because it is expected to produce a blue shift. 

Gas-discharge lamps are used to optically pump the metastable helium atoms into a higher excited electronic state, which has a dipole-allowed transition to the ground state. Only He (2 S) can be pumped selectively, thereby producing pure He(23S) beams. For the heavier rare gases, both metastable states are equally pumped by gas-discharge lamps. The use of cutoff filters to selectively pump one state is not adequate because of the temperature dependence of the filter transmission and the low / numbers of the pumping transition. Metastable neon can be selectively pumped by a continuous wave (cw) dye laser,60 whereas Ar, Kr, and Xe have so far only been selectively pumped by pulsed dye lasers.61... 

P4. J.H. Doonlin, Select Pumps to Cut Energy Cost , Chemical Engineering, 17 January, pp. 137-1 42 (1977). 

These equations have been analyzed in some detail by Lucht and Laurendeau (2) and Chan and Daily (3). When the laser is turned on, molecules in the state are pumped to the E state. Since the laser selectively pumps from one rotational sublevel to another, the other rotational sublevels in the E state can be populated only by rotational relaxation. If quenching, or electronic de-excitation, is fast compared to rotational relaxation, then only the laser coupled state will be populated. On the other hand, if rotational relaxation is fast then all the rotational states will be populated and in Boltzmann equilibrium. 

Therefore, as the NPSH available exceeds that required by the selected pump, the pump is suitable. Our task is now complete. 

Figure 17 Cuts through the 2D-IR pump probe spectra shown in Fig. 16b and c along the direction of the probe axes for selected pump frequencies which were chosen to match the peaks in the linear absorption spectrum (squares 1648 cm-1 circles 1620 cru 1 triangles 1610 cm-1 diamonds 1584 cm-1). The frequency positions of the pump pulses are marked by the vertical dotted lines. (From Ref. 42.)...

Draft specifications for equipment selection pump design... 

Last year we extended the application of the picosecond-jet technique to the study of the dynamics of isolated molecules in various stages of solvation with various solvents (water, alcohol, etc). - The idea was to study this controlled solvation and its dependence on the energy redistribution. Also we wanted to examine the photodissociation of these different solvated species or complexes following selective pumping by the picosecond laser. The systems we studied in some detail are azine-solvent complexes made in the jet with He or Ar as the carrier gas. 

Lasers have three primary components (Fig. 4) 1) an active medium that amplifies incident electromotive waves 2) an energy pump that selectively pumps energy into the active medium to populate selected levels and to achieve population inversion and 3) an optical resonator, or cavity, composed of two opposite mirrors a set distance apart that store part of induced emission concentrated in a few resonator modes. A population inversion must be produced in the laser medium, deviating from the Boltzman distribution thus, the induced emission rate exceeds the absorption rate, and an electromotive wave passing through the active medium is amplified rather than attenuated. The optical resonator causes selective feedback of radiation emitted from the excited species in the active medium. Above a pump threshold, feedback converts the laser ampler to an oscillator, resulting in emission in several modes. 

How to calculate line pressure drop and size and select pumps... 

Doolin, J. H. (1977) Chem Eng, NY (January 17) 137. Select pumps to cut energy cost. 

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