Page 238 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

208 Applied Process Design for Chemical and Petrochemical Plants

50 36 1 00
45 34 I 90
/8
40 32 HEAD CAPACIT)' 80 800
.... ..... r---o
EFFICIENCY
0 .... i-t"-- """-... - - 70 1- 700
...i 35 030 J I I z
v, 0 / <; ....
,... -TEMPERATURE RISE ,J ....
� 30 ci28 v ... ........ 60 � 600 a:
....
� � r-, 50: 500 i
� 25 � 26 �v -
a: - ' � ....
� o9!> � � �
.... :I! \ pO� �--
� 20 �24 v 4oG 400 �
p-,
..... � A' �� 11-it'I\ �� -- Li:: ....
ffi 15 � 22 ....-.....- 30 !!; 300 �
� 20 x. .--� I �� �.�· ...,.,.,,. Iii
j 10 20 200
1\/ c � ............ �
5 18 »: -...... - 10 100
L,
0 16 0 0
0 100 200 300 400 500 600
CAPACITY, GPM
Figure 3-59. Typical temperature rise for boiler feed water pump. (By permission, Transamerica De/aval Engineering Handbook, 4th ed., H. J.
Welch, ed., 1983, Transamerica Delaval, Inc., IMO Industries, Inc., Div.)
50
Temp. rise, °F/min = 40
(BHP at shutoff) ( 42.4) (3- 36)
(weight of liquid in pump) (c P ) 30

.... 20
or w
J:
z 15
w
a:
J:
cf 10
(BHP - WHP) (2545) ""'
c.?
Temp. rise ° F /min (3-39) w 8
( pump capacity ) 0
� 6
w
a:
::,
2. Minimum Flow (Estimate) [6] .... 4
cf
a:
w 3
CL
2
w
....
The validity of the method has not been completely 2
established, although it has been used rather widely in set-
ting approximate values for proper operation [10]. For
multistage pumps use only the head per stage in temper-
ature limit by this method. 300 500 1,000 2,000 3.000 5,000
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 lo 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 ofliquid.
c. Allowable temperature rise = t 2 - (actual pumping H, 0, at shutofffrom curve
temperature). Boiler feed water practice uses 15°F 778(6.Tr )cp + Hso, at shutoff (3 - 4-0)
rise for average conditions [10].