Page 240 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

210 Applied Process Design for Chemical and Petrochemical Plants
.. ate often should be placed in service on a regular sched-

Pa- 1 af 1 P1111u ule just to be certain they are in working order.
Unit P,ic• 2 (one a.a SP!l e}
IIMNo.------ If solids are carried in the fluid, this can present a diffi-
CENTRIFUGAL PUMP SP!CIFICATIOHS No. Unit, P-(P A & B
cult problem if they are not properly flushed from the
DESIGN OAT.A pump on shutdown. Some spare or second pumps are
Senl,;e Forwarding to T-98 Llq .. ld �7-'%� · � C= au=s � t= 1c � ------r
"Solid, Nppe Colc-.GPM_� 1= 8---- Dn.GPM_.- 22�-----< selected for 100 percent spare; others are selected so that
Ve,.rPr.H. PSIA T•mp, � °F Vi,. � Cp Sp.Gr. 1.0f each of two pumps operate in parallel on 50 percent of the
HUD SUCTION DISCHARGE DIFFERENTIAL flow, with each being capable of handling 67 to 75 percent
+ 4.1 •.. + 12.1 F,.
Stalic Ft. Ab .. -
==:=2�g:'.:; : g;::=== F;;, Ab,. + 199.R •.. 11'.R . .. of total load if one pump should fall off the line. This then
3,4
+
--�o� .1�-••· + 199.9 . .. only reduces production by about 25 percent for a short
•..
Tatal �+--'lc,,2� .1�-F,. Ab,. + 207.3 Ft. Abs. + 195.2 . ..
NPSH Availab/111 9.5 Ra1in9H•ad 196 to 200 F•, period, and is acceptable in many situations. These pumps
PUMP SELECTION are usually somewhat smaller than the full size spares.
Mfgt. "A" Siu & r,,..Centr1fupal, 2 x 'Jilodel AAA Ca •• Ty,.-V � rt ·-�
St19H One Imp. TypaEnOl0§9d Da1l11n l111p, Dia. 1� 1/f" Maic.Jmp. Oia. _ __o1�4�-----! When it is necessary to plan several pumps in parallel,
0,1... Motor RPM 1750 Dul;n En. 13% Ratal/vn• Counter Clockwise the pump manufacturer must be advised, and care must
Ra1lftf BNP�Nvn•OHrlOGd BHP-1.5..____ Shul•aff P,.,,, 14} ps1p; NPSH R•quirad,_-,�,--=-ft�·----!
S1,1e. b�otlon End Disch. Locotion VertlC{ll Top eu,.,. No. C - 12� be taken in arranging suction piping for the pumps, oth-
CONURUC'TK>N,.MA'JERIAiU
erwise each may not carry its share of the flow.
There are many flow conditions, and pumps should be
Packing ihdt S.al: lnt•rnml C Eat11rn•I O Ph.,111•d LJ
Slufflng Bo:ir s-1 Cag• Bu•hln111 Glcrnd Bolt. ----I selected to operate as efficiently as possible over the
MechanlcalS.al1 Mak• � Type � ; Coolant�;l1111deC Our•ld•l:!'J Sin;l•CI DoubleC
V
Bcr•911lete Cast Iron Cawp!in11:Mf11. '1 A" Typo � _ e __ GuQ1d_--"""e•.._ __ widest range of capacity.
Bearln1•1 Type Bell, double MQ\ie CoclQnt --�-----<
l111P•ll•rNu1 N!Ckel Tl,ru•t B•crring1: T1p• � br!Ca.ted M11ke_•_. •z � •-----l If the flow is expected to vary during the system opera-
eo.. Srud, Nl eke) ea •• End CQWlllr'l _�N= ! c=k=e� l _ tion, the high and low GPM (and corresponding heads)
DHFu •• ,a Nickel Oiopl,rcrgrn ----------
Plpl"11 _llike_,,_ l should be given to allow proper evaluation.
0���------,,�.�-
� ·=·• � tl• � n �� n:!,;;; � '="====== � ·= ·" � ''..:;1S=Q � #:;;::;5t � 4 � ,;;;;; � Dl � •<h � · � ·· � S1 � u:::=::::;;;;;:;;:;:..:•: •• � • �� = l' �� n..O � • � • � :;;;;; �
DlllYER
r,,.. TEFC Mfgr, __ --"B----c-c�---- Hp - � 1 � � Fluid Conditions
-c-c-----1
'
•
RPM 1750 Fra- Yolt,�4�4� 0 __ PhcrH __ � · __ Cyde GO
Elec. Clau_. CoN1eclion: Dit•d�.;-- Belh c;.., ��
l•l•tS,._ PSIG� __ .,. Ellh11U1tStca,,, PSIG�-----...c"F. The manufacturer must be told the conditions of the
St•-Rohl
RE.WAR KS liquid, percent suspended solids, physical properties, cor-
• facing P•,np rrll!l'I Drivar En.,.
rosive nature and maximum and minimum temperature
.. , •... , •... ranges. For extremely hot liquids, special hot pumps must
be used, and temperature effects taken into account.
o ... I la.,•, . I I Rev, I !
P.O. Ta:---------------------------'
System Conditions
Figure 3-61. Centrifugal pump specifications.
The manufacturer must know if the suction side of the
pump is associated with vacuum equipment, or is to lift
gestions for materials of construction for pump parts in the liquid. This can make a difference as to the type of
the services indicated. The effect of impurities, tempera- impeller suction opening he provides. If the system oper-
ture, analysis variations and many other properties make ates intermittently it should be noted. A piping diagram is
it important to obtain specific corrosion service data in often helpful in obtaining full benefit of the manufactur-
the specific fluid being pumped. Sometimes this is not er's special knowledge.
possible, and generalized corrosion tables and experience
of other users must be relied on as the best information Type of Pump
for the materials selection.
If there is a preference as to horizontal or vertical split
casing, it should be stated. Also the suction and discharge
Number of Pumping Units connections should be stated as to top or end, or special,
together with the preference as to flanged (rating) or
A single pump is the cheapest first-cost installation. screwed. Small pumps are commonly furnished with
However, if downtime has any value such as in lost pro- screwed connections unless otherwise specified.
duction, in hazards created in rest of process, etc., then a
stand-by duplicate unit should be considered. A spare or Type of Driver
stand-by can be installed adjacent lo the operating unit,
and switched into service on very short notice, provided it Pumps are usually driven by electric motors, steam or
is properly maintained. Spare pumps which do not oper- gas turbine or gas (or gasoline) engines either direct or