Best efficiency point for

The best efficiency point for the furnished impeller shall preferably be between the rated point and the normal point. 

It is a characteristic of process equipment, that the best operation is reached, at neither a very high nor a very low loading. The intermediate equipment load that results in the most efficient operation is called the the best efficiency point. For distillation trays, the incipient flood point corresponds to the best efficiency point. We have correlated this best efficiency point, for valve and sieve trays, as compared to the measured pressure drops in many chemical plant and refinery distillation towers. We have derived the following formula ... 

Figure 3.5 illustrates this relationship. Point A is the incipient flood point. In this case, the incipient flood point is defined as that operating pressure that maximizes the temperature difference across the tower at a particular reflux rate. How, then, do we select the optimum tower pressure, to obtain the best efficiency point for the trays Answer—look at the temperature profile across the column. 

GENERAL NOTE This Standard does not cover exact hydraulic performance of pumps. Information on approximate head and capacity at the best efficiency point for standard pumps is for general information only. Consult manufacturers regarding hydraulic performance data for specific applications. 

P035 Best Efficiency Point for Rated impeller BEP N 13 m%... 

The purpose of the pump is to produce a certain flow against a certain pressure. This is done at a certain efficiency. The optimum point at which the efficiency is at a maximum is called the best efficiency point. For every size or design of pump, there is a best efficiency point at a given speed. The performance of the pump is plotted on a curve of head versus flow (Figures 8-3 and 8-4) By combining different sizes of pumps on a single chart, a pump tomb chart is produced (Figure 8-5). 

However, the largest operating cost for many process units is the energy supplied to the reboilers. We should therefore avoid high reflux rates, and try to achieve the best efficiency point for distillation tower trays at a minimum vapor flow. This is best done by designing and installing the tray decks and outlet weirs as level as possible. Damaged tray decks should not be reused unless they can be restored to their proper state of levelness, which is difficult, if not impossible. 

Step 1. Calculate parameter B (pump performance Reynolds number adjusted for specific speed) as follow For multistage pump, use head per stage for Hvb 4] 7 i (pump head an best efficiency point for water). 

According to HI convention, for double-suction pumps, Q is half of the total pump flow, ie, taken per impeller eye. The value of S is calculated at the best efficiency point (BEP) at maximum impeller diameter. 

Low Flow Operation. The optimum operation of a pump is near the best efficiency point. Some manufacturers curves indicate the minimum allowable continuous stable flow (MCSF) limits for every pump (43). In the 1980s, the processing industry experienced a reduction in flow requirement as a result of business downturn and installation capacity downsizing. The pumping equipment, however, was generally not replaced by smaller pumps, but was forced to operate at reduced flow rates, often below allowable MCSF. This has resulted in increased failure rates and reduced pump component life. 

Wliere N = the speed of the pump/motor in revolutions per minute Q = the square root of the flow in gallons per minute at the Best Efficiency Point BEP. For double suction pumps, use A BEP Flow. NPSHr = the net positive suction head required by the pump at the BFiP. 

Although the pump was being run at 25% of the BEP (Best Efficiency Point), it was designed for this type of service. This eliminated improper operation or running outside of the Sweet Zone. 

Figure 3-57. Viscosity performance correction chart for small centrifugal pumps with capacity at best efficiency point of less than 100 GPM (water performance). Note Do not extrapolate. For small centrifugal pumps only, not for axial or mixed flow. NPSH must be adequate. For Newtonian fluids only. For multistage pumps, use head per stage. (By permission. Hydraulic Institute Standards for Centrifugal, Rotary, and Reciprocating Pumps, 13th ed.. Hydraulic Institute, 1975.)...

Best efficiency point (BEP), 21 63 Best (Management) Practices for fertilizers, 11 127 in operation and maintenance,... 

BEP Abbreviation for best efficiency point the point or capacity at which a pump achieves its highest efficiency. 

Specific speed is calculated for the pump s performance at best efficiency point with the maximum diameter impeller. Specific speed is expressed mathematically by the following equation ... 

For a tray to function reasonably close to its best efficiency point, the dry tray pressure drop must be roughly equal ( 50 percent) to the hydraulic tray pressure drop ... 

A single-suction centrifugal pump is driven by a 60-Hz ac motor. The pump delivers 10,000 gal/min (0.63 m3/s) of water at a 100-ft (30.5-m) head. The available net positive suction head is 32 ft (9.75 m) of water. What is the best operating speed for this pump if the pump operates at its best efficiency point ... 

Weak compounds which are already big and thus have a very poor ligand efficiency are usually not the best starting points for further chemical elaboration as their optimization will most likely be difficult and time consuming. In many cases, fragments with high ligand efficiency are much better starting points. 

The PSE operates between the mixer-settler and the dispersion range with frequencies between 60 and 150 min , and amplitudes below 10 mm. Maximum throughput is then ca. 60 m /(m h) with minimum holdup and a good separation efficiency. The best operating point for the PSE is with a pulsation frequency of 10-20 strokes/min above the pulsation frequency for the maximum flooding point [6.44] (Fig. 6-37 in... 

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