Page 236 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

208 Applied Process Design for Chemical and Petrochemical Plants

600

700
600
w
b
500 8
m
400 3
w
w
300 2
%
200
100
0

Figure 3-59. Typical temperature rise for boiler feed water pump. (By permission, Transarnerica Delaval Engineering Handbook, 4th ec
Welch, ed., 1983, Transamerica Delaval, Inc., IMO Industries, Inc., Div.)

Temp. rise, 'F/min =
(BHP at shutoff) (42.4)
(3 - 36)
(weight of liquid in pump) (c )

or

(BHP - WHP) (2545)
Temp. rise ' F/min = (3 - 39)
(pump capacity )

2. Minimum Flow (Estimate) [6]

The validity of the method has not been completely
established, although it has been used rather widely in set-
ting approximate values for proper operation [lo]. For
multistage pumps use only the head per stage in temper-
ature limit by this method. 200 300 500 l.000 2000 3,000 SPOO
TOTAL HEAD, IN FEET

a. Determine NPSHA available at pump suction Figure 3-60. Temperature rise in centrifugal pumps in terms of total
head and pump efficiency. (By permission, Karassik, I. and Carter,
b. Add the NPSH value to the vapor pressure of the R., Centrifugal Pumps, McGraw-Hill Book Co. Inc., 1960, p. 438.)
liquid at suction conditions. This represents the
vapor pressure corresponding to the temperature of d. Approximate minimum safe continuous flow effi-
the liquid at the flash point. Read temperature, t2, ciency:
value from vapor pressure chart of liquid.

c. Allowable temperature rise = t2 - (actual pumping Hsn, at shutoff from curve
temperature). Boiler feed water practice uses 15°F eEr1 = 778(AT, )cp + Hsn, at shutoff (3-40)
rise for average conditions [ 101.