Page 277 - Chemical process engineering design and economics

256 Chapter 5

Table 5.16 Approximate Pump-Sizing Calculation Procedure_______

1. Define the flow system, i.e., locate points 1 and 2. The pressures pi and p will
2
be known at these points.
2. Locate the process equipment according to the rules-of-thumb listed in Table
5.14.
3. Estimate z t and z 2.
4. Estimate the frictional pressure losses E and E using the rules-of-thumb given
s D
in Table 5.15.
5. Calculate the pump work from Equation 5.48.
6. Calculate the pump shaft horsepower using Equation 5.49 and the pump effi-
ciencies given in Table 5.13.
7. Calculate the electric-motor horsepower using the motor efficiency given in
Table 5.9.
8. Select a standard electric-motor horsepower using Table 5.10 to obtain ap-
proximately a 10% safety factor.

Example 5.4: Approximate Pump Sizing
It is required to estimate the amine-circulating-pump size in the separation process
shown in Figure 5.4.1. The pump, which is a centrifugal pump, will be delivered
six months after placing an order. In order to put the process on stream as soon as
possible, a process engineer must place the order within three days.

Air Cooler To Add Gas
Disposal

Absorber

Scrubber

Figure 5.4.1 An acid-gas-removal process. From Ref. 51.

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