STANDARD
DATA
BOOK
-
PART
( P A G E i OF
III
----
DaUM STZING
J F C ~ ~ Is-! C ~ ~ ,
*
. I
TAELE OF CONTEXTS Ptc5
ex,Pmr3
Sunma ry
R , i \ l,N@, k . z1 z I
R ZX.
D e s c r i p t i o n and S e l e c t i o n o f Process Drums
.-
-~
1 -.
1
-
I 2
Liquid Surpe Crux D ~ s i ~ n
2
Liquid-Liquid S e t t l e r Cesign
€
L1apor-Liquid S e p a r a t s r Design Vertical Separator Vaoor and Two I m i s c i b l e Liquids vzpor and One Liquid Phzse I n c l u d i n g Knock-Out Drums H c r i z o n t a l Seoara t o r Vzpor and Tho I m i s c i b l e Liquids S c g a r z t o r w i t h a Eeavy Liquid P o t Vzpor and One tiqu.id Ph
c 1G ?2
.. -
_L -c '1 I
--
I -
15 17 212
Prccecs S t ~ z nDrums
27
.tux: 1 i a r y E c u i ~ ~ e nand t Drum I n t e r n a i s Ui re-?*.esh E n t r a i n z e n t Se7ara:or Fes? and g u t l e : koz:les Drains and Vents Draw G f f 5 c z z i e S i z i n g - Vortex Breakers tieads
2: 2;
---
LZ
2L
32 T:
---..-----..-- -
k s i g n Cri i ~ r2 i f o r S-c- c i f i c Process An?! i c z t i o n s L i g u i c ? - ? S F 5 b r z ~l i c e czt;-g- L / 3 2 a t i c f c r P r o c ~ s sCrgns 7*,
us ,:,I
-
4-
7.
.---*.'=:
:,-c.-. , I C?:~CC~
- *+
TEZ??1 :
isj'i
Tc>le 2 :
Se5~en:al Arezs f c r Chord !dicth/Diane;er R a t f c s Uc t o 3.5
Ficjure I :
P z r t i a l C a p a c i t y f o r 5 - 5 0 X i q u i d Depths i n C y l i n d r i c z i S h e l l s ( p r f: o f 1 enor: )
Caztcir:f
.
and Surf2ce Area of C y l i n d r i c a ; Orucs 2nd S:ar;dard
F i g u r e 2:
P a r t i a l Capecity f o r 5-50:
FSpsre 3 :
P a r t i a l Caijzci t:; f c r 5-50",tiql;id
F i c u r e 4:
P a r t i a l C z ? a c i t y f o r 5-50': Radius = 0.06 D)
i n 2:;
LC
- -F
dd
Hezds
- -cz --
E l l i p t i c i i &ids
62
Liquid D e ~ t h si n Hmis;heric.i Eeo;hs
3rLim i;iedds
d"
I
Liquid Depths i n Dish?? Seads (KRuckie
6:
Fi5uI-E 5:
P a r t i a l C t ~ a c f t yf o r 5-5GXL;quid Gepths i n Standzrd Dished Hezds
62
Fictrre 6:
P r e l i n i n z r y Diamzter o f fiori:or;tal
63
F i s u r e 7:
S u b n e q e n c e C h a r t f o r D r z w O f f Nozzle S i z i n g
Vapor-Liquid S e ; a r a t c r
6 3;
-
. CCNFISE1
-
I N c t t o be Re;r~ducitd
---.
" u LUMMUS C"
-
S J A N O A R r B - + & ~ ~ *--PART DRUM SIZING
III
P A G E 1 OF 63 January, 1972
The purpose of t h i s chapter i s t o provide t h e design methods and c r i t e r i a t o be generzlly applied f o r s i z i n a t h r e e b a s i c types o f process drums: l i q u i d surge drums, l i q u i d - l i q u i d s e t t l e r s , and vapor-1 iquid--s e---p a r a t o r s , i n c l u d i n g process steam drums. . The methods o f f e r e d i n t h e chapter r e p r e s e n t a good design p r a c t i c e f o r s i z i n g the mzjority of tc d r b ~ sfoi.ind iti process desigr: work. Hawever, nzi m e rnetbcd or c r i t s r i c ? rhou:.? t e csn::'&-d be a p p l i c a b l e t o a l l c a s e s . Design cases such as t h e ones l i s t e d below may r e q u i r e c e r t a i n depart u r e from t h e s t a n d a r d methods given i n t h e chapter.
*
*
*
Separation o f two l i q u i d phases of very c l o s e density. Separation of two l i q u i d phases when one l i q u i d i s i n t h e form o f very f i n e l y d i s p e r sed d r o p l e t s . Renoval of a small amount of f i n e 1;iquid -. m i s t from a vapor phase.
These and o t h e r s p e c i a l s i t u a t i o n s may be b e t t e r and more economically handled w i t h devices such as v e r t i c a l and h o r i z o n t a l b a f f l e s , coalescing pads, and s p e c i a l wire-mesh arrancenents. which may be i n s t a l l e d i n o r d i n a r y process drums t o achieve a more e f f i c i e n t separation. Tho s i z i n g techniques required f o r designing t h e s e more complex drums can be developed a f t e r considering t h e s p e c i a l c h a r a c t e r i s t i c s of each case.
I
I
!
DESCRIPTION AND SELECTION OF PROCESS DRVYS There a r e t h r e e main types of process drums coimnonly used by Lumus f o r which s i z i n g procedures and d e s i ~ nr e c c m e n d a t i o n s a r e given i n t h i s chapter. They a r e
* *
I
I
Liquid Surge DrumsLiqtrid-Liquid S e t t l e r s . Yapor-Liquid Separators.
The s e r v i c e L+at each type of drum gives i n prscess p l a n t s and same t y p i c z l pmcess a z s l i c a t i o n s f o r each type a r e dercribed i n t h e f o l l o w i n s subsections.
I
Liquid s u r s e drums a r e used t o provide s t c r z g e o r surge cspacity f o r l i q u i d s t r e w s w h i d a r e s u b s t a n t i a l l y f r e e o f vapor. As running s t o r a ~ ef o r t h e feed t o o t h e r precessing u n j t s , they provide a convenient way o f a s s u r i n g r e l a t i v e l y c c n s t a n t o r r a t e - c o n t r o i l e d flow. Surse dmrs may be bujl t i n e i t h e r h o r i z o n t a l o r v e r t i c a l p o s i t i o n s .
'There i s no o o e r a t i o n a l a d v a n t z c ~fcr ~ i t h a Dr O S- ~* -i o n . The drum i s positioned bzsed on the a v z i i a b l e space acccrding t o p l z n t l a y o u t , the c o s t o f supporting s t r u c t r r r e s , e t c .
I
1
S e t t l i n g tanks a r e used t o s e p a r a t e tuo i m i s c i b i e l i q u i d s of di-rferent d e n s i t i e s which a r e e s s e n t i a l l y vapor-free. To achieve aood s e 3 a r a t i o n i n a s e t t l e r , t h e hold-up time f o r a l i q u i d phase should be l a r g e r than t h e time required by the d r o p l e t s o f the o t h e r phase t o s e t t l e o u t from t h i s phase. Horizontal drums p m v i de higher hol d-up t i m e / s e t t l i n g time r a t i o than v e r t i c a l drums. Theref o r e , s e t t l i n g tanks a r e normally h o r i zontal a s shown i n the f i g u r e .
f ;/I\
il
Light Liquid
- Interface Heavy Liquid
-
11
,-------L-
Typical proc2ss a p p l i c a t i o n s r e q u i r i n g l i q u i d - l i q u i d s e t t l e r s a r e
** K-+Caustic-wash hydroczrbon s::s:e?s. a , r r - ~ a s h hydroczr5on sysEens. Sol vent e x t r a c t i o n sys t e a s . CO,,:F--n :t~t. .-l ! l k KC:J.U.EICT i
I
-
:to1 to be Reproauced
I
r* I
I
STANDARD
DATA
LUMMUS
B 0 6 ~ " - P A R Ti 1 1 -
DRUM SIZING
67
P ~ G E2 b~ January, 1972
Vapor-Liouid S e o a r a t o r s
main f u n c t i o n o f t h i s t y p e o f drum is t o s e p a r a t e v a p o r - l i q u i d mixtures and d e l i v e r sub/ si nt a enThe t i a l l y l i q u i d - f r e e vapors t o o t h e r process u n i t s . The v a p o r - l i q u i d s e o a r a t o r s may be b u i l t i t h e r v e r t i c a l o r h o r i z o n t a l p o s i t i o n a s shown below.
-
I
--
_ - . _-- - _ -
-
-.*-
- --.
.-
-
--
--
--
VERTICAL
Ti/([)
HORIZONTAL
L i g h t Liquid
-
Interface
-
Heavy Liquid
Y e r t j c a l v e ~ o r - l i ~ z i ' sde z a r a t z r s a r e p r e f e r r e d f o r h a n d l i n g m'xt2res w i t h h i s ; va~3r/:i<:iC nzss flow r a t i o zna u s u a i l y oniy one l i q u i d phase. In c e r t a i n c z s e s , :he v z o o r - l i q u i d s e z ~ r < = S c n may t z k e p l a c e simultaneously with t h e s e t t l i n g s e p a r a t i o n o f two l i q u i d phases. i n :he c z s e s where only a small amount of heavy phase i s p r e s e n t , v e r t i c a l drums may s t i l l be used. Typical a p p l i c a t i o n s o f v e r t f c a l vzoor-l i o u i d s e o a r a t o r s a r e
* R e f l u receivers. * Flash drums.
P m c e s s compressor knock-out drums. Fuel gas knock-out d r m s . Continuous blowdown drums.
.
Horizontal vaoor-? i o u i d s e o a r a t o r s a r e p r e f e r r e d t o handle t h e f o i lowi ng c a s e s : Kixtures with low v a p o r / l i q u i d iilzss flow r a t i o and o n l y one l i q u i d phzse. Mixtures c o n t a i n i n g vapor and two i n m i s c i b l e l i q u i d phases. An a t t a c h e d p o t may be used i n c e r t a i n c a s e s t o c a t c h t h e heavy phase o u t s i d e o f thedr;lm.thuS p e r m i t t i n g b e t t e r c o n t r o l o f t h e o p e r a t i o n and p o s s i b l y r e d u c i n g t h e d r ~ ms i z e . Typical a @ p l i c a t i o n s o f h o r i z o n t a l v a o o r - l i c u i d s e o z r a t o r s a r e
*
*
*
Overhead condensate r e c e i v e r s on crude o i l d i s t i l l z t i o n u n i t s . Water disengaging drums. Reflux r e c e i v e r s . Steam Drums. I n t e m i t t e n t blowdwn drums.
C) &,TOGID
SURGE DRUM D E S I G ~
Des i on P r i n c i ol e s
( 1 ) Surge t i n e to be s e l e c t e d from i n f o r n a t i c n on Pace 35, o r a s p e r s p e c i f i c p r s c e s s consicer::~ons issned by Process Design Mznzger o r L ~ a dI ~ D CEngineer. ~SS
--
---
-*.-
--+
:--
,-
.
' -- -
?-.
LIQUI D'*WRG€ DRUM DESIGii
HORIZONTAL SURGE DRUM L i q u i d Feed Nozzle 1I-
The h i g h and low l i q u i d l e v e l s indicate the e f f e c t i v e measuring range of the-gauge' rJlXs~s'?eV@l.
II
1
L i q u i d Level -
Low L i q u i d Level-
SIZING
Notes Vent -
-
- -High
DRUM
F..;r
- --
zczz?25 i n s t a ! 'e.5 cfi
t h e s h e l l , t h e minimm dimensiori from the t a n g e n t .l i n e t o the center l i n e of t h e nozzle is (6 + d ) in.
-- -
where d = n o z z l e diarneter i n inches .
I
3
L i q u i d 1O u t l e t Nozzle
I
I
I
I
I
Tangent Line
Tangent Line
-LA
i
h or-
and hb = 9 i n . o r s e t by s t z n d a r d p r a c t i c e % .c C J Z U ~ C g l a s s E e l -i n s t a l l s t i o n .
I
Ve n r_ -
I
1
I
I
I
Too T a n g e n t L i n e
I I
- - - HighLevel L -i-q u i d - -
L i Nozz q u i d 1eFeed
t! 1
i
c
D-
--
I
Liquid - Level
-Low
I
I
!
I
I
I
or set& standard p r a c t i c e s for gauge g l a s s l e v e l i n s t a i l a ~ o n .
hV and hb = 6 i n .
Eottcm T a n g e n t L i n e
Liauid O u t l e t Nczzle
.
-
-
E* (2)
STANDARD
DATA
LUMMUS
DRUM
BOOK
- PART
SIZING
I11
P A G E 4 OF 63 January, 1972
roe volurpe, corresponding t o above, ~ h o u l dbe e q u i v a l e n t t o 8 0 - 9 E ~ f t- h e t o t a l drum volume, % t e r accounting f o r useful head volume.
(3) See discussion on Page 36 f o r suggested L/D ranges. ( 4 ) See drawing cm Page 3 f o r additional design - r e c o m n d a r i e n s . i -
Examole.
-
A horizontal drum i s t o be designed f o r holding l i q u i d e t h y l e n e a t -110°F and 90 p s i a .
Ethylene flows i n t o t h e drum a t a r a t e of 35,000 'Ib/hr. having a d e n s i t y of 33.2 1 b / f t 3 a t t h e above flow conditions. The drum i s feeding a r e a c t o r , and i t receives t h e l i q u i d ethylene from o f f - s i t e storage.
(1) S e l e c t a surge time, TS = 12 minutes. Since P > 50 p s i g , a standard s i z e i s not a v a i l a b l e . S e l e c t an L/D of 3 . :
1
..
j
Yo1 m e t r i c flow r a t e : Q1 =
j
u1 q
=
35*000 T60)(33.2)
=17.57ft3/min
( 2 ) Surge volume required:
(17.57)(12.0) = 210.8 f t 3
CONFIDENTIAL D0CUYE:iT - Not t o be Reproduced
.
v
1
EE LUMMUS -
DATA . 8 0 0 K
STANDARD
- PART
111
P A G E 5 O F 62 January, 1972
DRUM SIZING
I
( 4 ) According t o recornended values f o r horizontal drums.
A
-
.
-
hv = 9 inches -
L
.
.-
-
hb = 9 inches
( 5 ) Since t h e mechanical design p r e s s u r e w i l l be above 100 psig f o r a drum with an o p e r a t i n s press u r e of 90 p s i a , s e l e c t 2:l e l l i p t i c a l heads f o r a 5 f t diameter drum. (6) Consider the a d d i t i o n a l volume contributed by t h e two heads i n order t o o b t a i n a more ecsncmicat s i z e .
X Depth a t 9 inches:
(9)(100)/60 = 15% (Low l i q u i d l e v e l )
% Depth a t 51 inches:
(51)(100)/60 = 85Z (High l i q u i d l e v e l )
Fjom Figure 3: - - -(a)
-
(O)
-
Caoacity of 2 e l l i p t i c a l herds a t 85: depth with 5 f t diameter: 231 g a l s . / CapacSty of 2 e l l i p t f c z l h e 2 6 a r 15% dept? w f t h 5 ft diaaeter:
/
15 g a l s .
Then s u r q e vo'ime i n t h e tdo hezds:
vo 1ume 1e f ime,m :
(a)
Capacity o f a 5 f t d i a m e t e r s h e i l a t 85% d e ~ t h :135.L-gaj/ft
(b)
Capacity of a 5 f t diameter s h e l l a t 15% d e ~ t h : 13.8 --- g-a I / f i p e r f t o f s h e l l
per f t of s h e l l
Surge v o l u m p e r f o o t of s h e l l :
Lenqth o f s h e l l :
-
Say:
(7) Final dimension;:
11 - 5 f t (saved 2 f t i n s h e l l l e n g t h by accounting f o r volume o f heeCs.)
u= L
3
--.
Fr
11.5 ft L/D = 2.3 (Low, b u t a c c e p t z b l e ) '!\ hv = 9 inches /. hb = 9 inches h i = d i s t a c c e between low a n d high l i q u i d leveis = 42 i n . Two 5 f t d i a r e t e r e i l i p r f c a l hezds ---a
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--
--
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r
E<
STANDARD
DATA
LUMMUS
BOOK
- P A R T 111
P A G E 6 OF63 January, 1972
DRUM SIZING !
6 . 1 1
'blltFR
Earn
In -the-seprration by s e t t l i n g of two l i q u i d phasis o f markedly d i f f e r e n t d e n s i t i e s , The dmpl e t s o f t h e heavy pnzse have a tendency t o fa11 down and o u t o f t h e l i g h t phase under t h e i n These heavy-li?~lid dmnlets a r c ~ ! e r z t e u n t ? ? :kc f r ' c t j ~ c s ! d r a g force fluence o f g r a v i t y balances t h e g r a v r t a t i c n a l forces. A t t h i s p o i n t , t h e heavy d r o p l e t s continue t o phase o u t o f the, l i g h t l i q u i d a t c o n s t a n t v e l o c i t y . This i s t h e terminal o r f r e e - s e t t l i n g v e l o c i t y . An analoaous mechanism a p p l i e s t a m e s e p a r a t i o n of t h e l i g h t - l i q u i d d r o p l e t s t h a t may be p r e s e n t i n t h e bulk of the heavy phase, except t h a t i n t h i s case the d r o p l e t motion is upward, and t h e f r i c t i o n a l drag force created by t h i s m t i o n is opposed by t h e buoyancy f o r c e s i n s t e a d of g r a v i t y . Desfcn P r i n c i p l e s -(1)
The o b j e c t i v e of t h e s e t t l e r is t o achieve an e f f i c i e n t l i a u i d - l i q u i d s e p a r a t i o n , and n o t t o provide surge vo7ume. Once t h e l i q u i d - l i q u i d s e t t l e r has been designed, c e r t a i n mechanical arrangements silch as b a f f l e s can be i n s t a l l e d t o provide s u r g e v o l m e w i t h i n t h e sane drum.
(2) For t h e p a r t i c l e s i z e s comonly found i n i n d u s t r i z l l i q u i d - l i q u i d s e t t l i n g o p e r a t i o n s , t h e
following equation based on t h e Stokes Law gives t h e f r e e - s e t t l i n g v e l o c i t y f o r t h e d r o p l e t s o f one l i q u i d o u t of t h e o t h e r continuous K q u i d phase. =
where
I
'
ks
.hid, b u t n o t uc
t o e x c ~ e d-1
1A, 2 4 r ? / k M '1
ph = Densjty of heavy l i q u i d phase, 1 b / f t 3 PI
= Density of l i g h t l i q u i d phase, 1 b / f t 3 /
'
cc = Viscosity o f continuous phase, c e n t i p o i s e
I
I f t h e rninimua p a r t i c l e s i z e f o r a given d i s p e r s e d l i q u i d phase is known, t h e following eqlraL ~ , R is used: where d i s t h e p a r t i c l e s i z e i n inches.
'I
Since d is not generally a v a i l a b l e , t b e foilowing titb'le can be used t o s e ' r c t a value f o r ks:
L i o h t Phase
Heavv Phzse
Assumed Hininun Drcpiet S i z e
Hydrocarbons Sp.gr. et 60PF < 0.85
L a t e r o r Caustic
0.005 i n . = 123 z'crons
Sp.gr. @ 60°F > 0.85
Water o r Caustic
Water Furfural MEK Water Sec-butyl alcohol Uater Methyl: isoburyl ketone Water Nonyl a1 coho1 Water
0.0035 i n . = EQ n i c r o n s \ O m'.w-s \---,---
I
45
0.333
0.163
n 3
c
L q :
2
( 3 ) The s e t t l e r design should comply with t h e requirement t h a f o r each continuous l i q u i d phase $he$e&-a@ i s l a r g e r than t h e s e t t l i n g t i r n e , b needed by t h e d r o p l e t s o f t h e d i s persed l i q u i d t o s e t t l e out. Therefore, according t o t h e accompanying f i g u r e ,
the r e t t l i n o veloc; r i ~ s2 the l i c n t q n d he~vv--. are i n feet.
T&c.% I
--
*A
-----
---
-
LIQUID-LIQUID SETTLER D E S I G N
.--
-
Lf ght Lfquid Drawoff Nozzle
Ltquid Feed (see d e t a i l below)
-
-
-
I
I
Interface
h, ( 1 f t minimum)
NOTES
hh ( l f t minimum)
1. For nozzles jnS:l!e? sn t h e s h e l l , the ti;^::,dimnsion frog the tzacent l i n e t o the cent57 i : r ~ o f the nozzle t s
--
(6tdl
Heavy Liquid Drawo f f Nozzle
!
1 I
where d
=
fn.
nozzle C:~-e'-er fn tnc$es.
I
Tznaeni Ljne
Tangent Line
L
2. The nozzles f o r
L
Detai1:Feed Pi;e Nozzle Arrz~gernents (Front v i e w ) Feed frcr, TCD
Feed f m m Side
Feed t h r c u ~ hHead
-
I
\,
- -Interface -
in
7
G
F u g e glass level .ir.s-.Ila:ic.r..
'.
rI
LUMMUS
STANDARD
'
DATA
BOOK
.
I L C L I . F
- PART
111
DRUM SIZING L/D
(4)
See discussion on Page36 f o r suggested
(5)
See drawing on Page 7 f o r additional design recomnendations. - .
Limi tations
-
--
PAGE 8 OF63 January, 1972
ranges.
.-..
%%
-L
-
The p r i n c i p l e s described above should not be applied f o r designing s e t t l e r s t h a t handle
-
Systems where one of t h e phases i s f i n e l y dispersed and amounts t o l e s s than 2: t o t a l flow r a t e .
of
tk .
S y s t e m where t h e d e n s i t y d i f f e r e n c e amounts t o l e s s than 10% o f t h e heavy l i q u i d density. Systems where an excessive foaming tendency i s expected.
In these cases, o t h e r separation equipment nay have t o be considered. Exam~le. A 50.000 l b / h r strean.containing 80% by weight of aromatics and t h e balance as water, is t o be delivered a t 100°F and atmospheric pressure t o a s e t t l i n g drum t o recover t h e a n rnatics. Desion t h e drum as a horizontal s e t t l e r . A t flow c o n d i t i o n s t h e physical p n ? e r ties are Aromatfc phase: (1
Preliminary design data:
(2)
Volumetric l i q u i d r a t e s :
p1 = 53.0 lb/:t3 p1 = 0.550 cp
01 = 40,DOO/ii50i(55.0)l
Qh
Water:
ph = 62.0 I b / f t 9 ph = 0.682 cp
= 12.58 f t 3 / n i n
-\
= 2.69 ft3/min
= 10,000/[(60)(62.0)]
Both values s a t i s f y : . v s e t t l j n g
<
10 inches/rr;in
~ r e 1 i n l n ; t r vmay be estimated from t h e expression
D = 2.3
\
a s s m i n g L/D = 3. Then
/ 9.90
D = 3.30 f t L = 3(D) = 3(3.30)
Rounding o f f ,
Ql V l
D
=
+
Qh Vh
, f t , where
Q i s i n f t 3 / m i n and v i n inches/rzin.
ft
= 3.5 ft
L = 10.0 f t L/D = 2.86. This i s O.K.
Proceed t o detennine t h e s e t t l i n g h e i a n t s of t h e l i o h t and heavy phases. Rake necessary a d j u s t rnents t o comply with t h e i l l u s t r a t i o n f o r l i q u i d - l i q u i d s e t t l e r des
I
us-
--
L
STANDARD E%ELUMMUS I ' .
DATA
eoou
- PART-
111 Decenber. 1975
DRUM S I Z I N G
3.5 = 0.62 f t &.A=.
6
hh = 1 f t [m;~imum h e i g h t )
i i
-
Then a c c o r d i w the recornended value,
!
and
hi = D
9-
- hh = 3.5
-
1.0 = 2.5 f t = 30 inches
(6) Check t h a t the - s
do n o t exceed t h e residence times.
12 (hh) -
th=
Vh
u.. 3
Fmm Table 2 f o r and
#=
Ah
=
2 2 . 2 7
Therefore eh >
and
( l o ) = 8 - 4 4 minutes
q,
A1 = A - Ah = 9.62 91 =
Therefore
(7)
Ah = 0,236 7 r
2.6%
Qh
Then
= 0.286,
Ah = 0.236 ( ~ / 4 ) ( 3 . 5 ) ~= 2.27 ft2
Then Eh =
' -' ,I
12 (1.0) = 2-73 minutes 4.39
A7 91
= '7.35
-
(10)
2.27 = 7.35 f t 2 = 5.24 minutes
12-58
> t.1
F i n a l Dimensions:
D = 3.5 ft L = 10.0 ft VD = 2.86 h i = 30 inches hh = 1 2 inches
h i = 2.5
ft Liquid Interface
hh = 1.0 ft
I I
1 ---
POR-LIOUID SEPARP.TCR DESi V e r t i c a l and h o r i z o n t a l drums a r e cornonly used tc seDarate v a p o r - l i q u i d mixtures. When o n l y one ' l i q u i d phase i s involved, t h e f a c t o r s a f f e c t i n g t h e desion a r e the vapor v e l o c i t y and, ifrequired, the- l i q u i d surge time. Whenever two i n m i s c i b l e l i q u i d phases a r e present, the desiori becomes more complex because t h e s e t t l i n g c h a r a c t e r i s t i c s of t h e two l i q u i d s be teken i n t o account. I n a d d i t i o n , process considerations may d e t e r n i n e t h a t an attached p o t or t r a ~ o u tboot be used t o c o l l e c t the heavy l i q u i d phases. The f o l l o w i n g sketch s u m a r i z e s the desfgn methods f o r v a ~ o r - l i q u i d s e p a r z b r s :
I
CONF!DEBTiAL
WCUt?ENT
-
Not to be Reproduced
ce
LUMMUS
S T AN DA R DDATA. -DRUM
(-I I I
B..OOK---P,ARf SIZING
III
.
P A G E 10 OF 63 January, 1972
I
[VAPOR-L IOUID S E P A ~ T O R S i
~?L
ONE LIQUID
TWO LIQUIDS
k d ,
.
'rj K.O. DRUMS
l&
J+
K.O. DRUMS
:I I
1
I I L3
-tfca1 S e ~ a r a t o r
i
I t i s not c o r w n p r a c t i c e t o use a v e r t i c a l drum t o s e p a r a t e a vapor and two l i q u i d s beczuse 2 u x i l i a r y i n t e r n a l s a r e generally needed t o e f f e c t a s h a r p l i q u i d s e p a r a t i o n . This e x t r a ~ ~ 2 f ; a e n tfrequently makes t h e c o s t higher than t h a t of a h o r i z o n t a l vesse7; a l s o t h e v e r t i c a l d r m i s f r e q u e n t l y l a r g e r i n diameter.
1
.
? a
I
-
Lfz!roor and Twu i m i s c i b l e Liquids
'
I
+'
)
L-nslder a feed t o a v e r t i c a l drum consist'ng o f gas, o i l , and water. The vzpor dire-"gas fmm the l i q u i d s . The b*. l i c d i c s f a l l through t h e drum, accumul a i t , and eventually build up i n t o two ;a:.,ers. %e b o t r o m ? t y e r can be w i t h crzwn w-ithcct carryirig o u t any of t h e c:l. However, i f the vessel does n o t ka-e the aopropriace i n t e r n a l s , t h e o i l i a y c r i s f i l l e d w i t h water d r o p l e t s w n i ~ ha r e s e i t l i n g t o t h e bottom. Con---.. 2=7Uent1y, i t w i l l be d i f f i c u l t t o withCrzv u a t e r - f r e e o i l . Several cases m y be considered then.
Vapor
-__
Z )
I f th'e t o t a l q u a n t i t y o f water is very small s o t h a t t h e amount withdrzwn with t h e of 7 w i l l have no e f f e c t on t h e process,.then a s i d e drawoff f r o n t h e vessel w i l l be s a t i s f a c t o r y , as i l T u s t r a t e d ,
u T
Light Liquid Drawoff
Interface
I
Heavy Liquid Drawoff
(b) :1 water-free o i l i s required, then a p p r o p r i a t e i n t e r n a l s w i l l be necess a r y t o achieve t h e s e p a r a t i o n o f t h e two l i q u t d phases. Consider f i r s t the case where t h e o i l q u a n t i t y i s r e l a t i v ~ l ysmall and t h e s e t t l i n g v e l o c i t y f o r t h e water o u t o f t h e o i l phase is much l z r ~ e rthan t h e s e t t l i n g velocity f o r the o i l out o f t h e water phase. In this i n s t a n c e , t h e o i l can be withdrawn through a hood, as shown.
Feed
Vapor T
Light Liquid Drawoff
The v e r t i c a l v e l o c i t y o f t h e o i l
r i s i n g through the hood must n o t exceed t h e s e t t l i n g v e l o c i t y f o r
-L
Heavy Liquid Drawoff
I N o t t o be Reproduced
I
EKE ~UMMUS S T A N D A R D
DATA
BOOK
(c) When t h e o i l v c l m e i s s o ? a r g e t h a t a simple hood c a n n o t be u s e d , t h e
P A R T X!I
.
.
DRL! STiIAG
t
-
PAGE 11 O F 1 2sntikrv. 1572
63
T Y F ~( c j --
I f q u i d m i x t u r e i s a?ioweb t o d r o p on a b a f f l e p l a t e and e n t e r i n t o a d d n s p l j u t which ends r b o v e t h e i n t e r face. 'The main d i f f i c u l t y w i t h t h i s d e s i g n I s t h a t t h e c m o l e x i t y o f the i n t e r n a l ~i n c r e a s f s the c o s t . I t I s the desf gn o f t h i s type c f s e p a r z t s r t h a t i s discussec! 5elow.
(1)
Light Ljquid Drawcff
For the vapor-Itquid
Brown equztion ~ i v e n
where 01 = h s i t y c f t\e l i g h t l i q t f C F ~ O S C , 1 b / f t 3 py = kr6itjr ~f the vzcrsr g.?ase, ;t/ftZ ,K = O . a f c r a v e r t i e f drrrs withad wi& mesh, cr I d m anrr msh
--
I 1
(Zj
For +A?ar=fcle sties cz.mzzlv f:rr?5 ir, inc'lrstrial l i q u i d - l i q u i d s e t t l i n c c p c r a t i c n s . u e follcdric eqsacfan t.crfd on t k e Szskes Lrr $vet "&t f r z e s e t t i i n g velocity f o r t+,e draplets of one licuic o c t of :Ae car.tfrm*s ~sF'.%ie-
':er:?irg
Tre ; r a i k e
TZ
>$
ks <;~-;!:.'.Jc
--
t c ~ : c - , e i :~ r ; . r----3-*
ssre m r : s j ~ - s t e - r 2
2
g:;-er!
.2c-oL-
but
not to
:J inc!!s/mir:
k, a r e d i s c ~ c s e ic;n F ~ S P6.
Vtlctes
t~c10~;
of kS for
( 3 ) The desicr; s h c u i l ccn;;!_v w i ttr the r e c u i r e c e n t L!?t f o r ezch c o n t i n l r c c ~phzse, the m i l e n c e t
-
e l > tl = -I. ? h: ri
"
> th =
vh
-
, nffiates
.
I
ninutes
uhere v l and vh a r e Lbe s e t z l i n g v e l o c i t ' e z i n t!e l i o h t a n d heavy ,!ieses. T6e se:t:ing n e i ~ 5 z r .h l acd h h , a r e f n f e e t .
n kt,
r--?
i
!
3& - 1 I p -
D-J
I
31 ---
11
7 - -
I - - - *
___q,
-
VERTICAL VAPOR-L IQUIT, SLrJARATOI( IIC5 lGN '
- --.
--
/
-
p
4
c.
*
-- - - ---
--
?
k
(One o r Two L i q u i d Phases; W i t h O p t i o n a l Wire Mesh)
- -- - - -.. ----.
.-
,@ b
'...
#
p.+3-- -
J l -tS -Kt\= If t h e r e
I
i s no wire-mesh e n t r a i n m e n t s c p a r a t o r .In t h e drum, thcn ht.0. I f a w i r e mesh i s used, p k e h + = l f t r n i ~ ~ i n a ~ r i . As f a r as the vapor-1 i q u i d s e p a r a t i o n soes. a l a r a< c. vaoor - s p ~ c cabove the w i r e mcsh i s u n n e c e ~ s a ~' ~ . I
-r
I (9 = T l ~ i c k n ~ sosf t h e wire-mesh entrainment s e p a r a t o r , r e f e r $0 I'agr! 29. Il c i g l i t .o f t-h e vapor - - space,-_ s e t
1
ItV
=.-0.5- D + 1/2(upper n o z z l e --diameter) -.--
b u t n o t smal l&than
-
I I i
1'
drum u f t l l o u t w i r e mesh) o r I: r c mesh)
I
. 1 Fced Nozzle .2
hn = 1 / 2 ( l o w e r nozzle dlameter) + 1/2(upper n o z z l e diameter), I a 1 t;Iiougli a minirnc~rno f hn=O can be used. 11
Gll~cri I1ot:li feed nozzles c o n t a i n t h e same r e l a t i v e vapor/ ' 1 i q 1 ~rl1 lodds, the III~n i ~ n ~ r hn m i s recosm~ended. The nozzle's : s l l o ~ r l dI)? l o c a t e d a t thc same e l e v a t i o n b u t o r i e n t e d allout 90' from each o t h e r . I
Feod Nozzle
For feeds o f d l f f e r e n t c h a r a c t e r i s t i c s , i t may be advan-: tdqcous t o space feed nozzles an a d d i t i o n a l 18 inch?s a l l a r t . Locate n o z z l e w i t h the h i g h e r v a p o r / l i q u i d r a t i o , on tlie top. I f t h e r e i s o n l y one feed n o z z l e , then hn=O. Ilbn(l,lln)
1/2(lower n o z z l e diameter) + . G r e a t e r o f ( 2 f t o r h S )
T h i s dlmcnsion s e t s t h e maximum h e i g h t t o which t h e I i q u , i d l e v e l w i l l be penni t t e d t o r i s e . I n c e r t a i n cases, such as i n compressor f i r s t stage knock-out drums, l i q u i d s p i l l s Froln p r e c e d i n q u n i t s can happen. I t i s then a d v i s , i ~ b l et o pr*ovlde a ainim~rnihs e q u i v a l e n t t o 5-10 a d d i t i o n a l ~ n i n u t e s o f surge time based on l i q u i d r a t e n o r m a l l y p r e s e n t i n t h e Feed.
hs
ha = U i s t a n c c from l i q u i d l e v e l t o t h e bottom s u r f a c e o f I ~ a f f l c , s e t Iia a t a l~iinintumo f 6 i n . i n c l u d i n g thickness o f b a f f l c plate. Ill.
-
I-"\ I
'->
Vapor Nozzle
-
Distance from hottom face o f t h e b a f f l e t o the c e n t c r l l r i t ? o f tlic l i g h t l l q ~ r i dnozzle. Tliis d l s t a n c e i s !;et t o s a L I s i y the rcquirenlcnts o f surge tillle f o r the l i g h t l i q u i d IIIIJSC. I f t h e r e a t e no r c q u i r c i n e r i ! ~ f o r surqe t i m e , til-~O in, l / ? ( l l < ~ l i l .' i i ( ~ \ r i r ln o x z l c d I , t ! w t e r ) ,
Ill, till = S e l L l i r t g h c l ! l l i t ~ I'or l i ! l l r t and Itcavy pliases.res!)ectlvcly.
hi) " 6 inctics o r s e t by s t a n d a r d p r a c t i c e s f o r gauge g l a s s l e v e l
installation.
Eg LUMMUS
'
'
STANDARD
DATA
BOOK
- P A R T I!i
I P A G E 1 3 O F 63
(
DRUM SIZING
Januzrv. 1972
(4)
The v e r t i c a l s e ~ a r a t o rmay be designed t o provide a surge volume f o r the l i g h t l i q u i d phase a t the expense of an increased vessel height.
(5)
See Page 36 f o r suggested L/D ranges.
(6)
See drawing on Page 12 f o r additional design recomnenda tions.
Examole.
,
In an ethylene unit, cracked gas containing a benzene-type hydrocarbon and water i s cocled t o 90°F, and t h e -li~~id'phas$"esre-to'-b'erFc;3bered-?~'a%i~r-lfqwi.j'se~irat o r . A v e r t i c a l drum with a wire-mesh mist e l i m i n a t o r i s s p e c i f i e d . Operatic5 pres. rcrge t i c ? f o r +he h v d r @ c d r h ~phase n S"re f 3 T C Z ,J - < - . -, a , 2:ld <; f 5 nec;.~:?i'jr TC ,,,f of 25 minutes .
1
h - 1
(1)
The given i n f o r n a t i o n , Mass Flow Rate, l b / h r
P,
U, CD
------
p v = 0.6973 pl = 53.95 ph = 62.11
WV = 415,000 W l = 16,500 Wh = 1,300
Crzcked Gas Hydrocarbcn Hater
7b/ft3
PI = 0.630
ph = 0.764
TS = 25 minutes f o r l i g h t phase. There i s no s p e c i f f e d heavy phase s a r c e time.
K = 0.35 (2)
, s i n c e a wire-mesh s e p a r a t o r i s recuired.
Vo?unetric flu4 r a t e s :
0,
Vapor: L i g h t Liqufd:
Heavy Liquid: (3)
= Wv/(60 9,) = 415,000/ (60)(0.6'373)] = 55;"fi3/min Ci = 'kl((60 p l ) = 16,509/ (60)(53.95)] = 5-10 f t 2 / n i n C.h = bib, (60 p h ) =. 1,300/[(00)(62.11)~ = 0.35 f t 3 / n i r .
grun d i s z e t ~ rk s e d on allowable vapor v e l o c i t y :
Round o i i t o n e a r e s t 0.5 f t , D = 8.50 f:. ,
(4)
The vapor cross-sectional a r e a is A = 0.7853 (D)'
= 0.7853 (8.50)'
= 56.75 ft2.
S e i t ? f n s v e l o c i t y o f t h e heavy I f q u i d d r o p l e t s c u t o f t h e l i g h t phzse, vl.
S e t t l i n a v e l o c i t y o f t h e 1 i g h t l i q u i d d m o l e t s o u t of-the-heaugshase,
(5)
VJ,.
S i z i n o of t h e b a f f l e p l a t e .
* S i z e the area Ab with t h e a i d o f t h e c h a r t below on With the above (o1-oV) vaiue and an assumed (ho
-
P2ge 14.
ha) = 24 i n . , G = C6CO.
Calculate another Ab f o r w = 4 incnes.
w/D = 4/[(12)(8.50))
= 0.0392. which corresponds t o Ab/A = 0.0130 i n Table 2
Ab = (0.0130)(56.75) = 0.737 f t : S e i e r t t 9 e l a r c e r one, fib = C.7c ft'
CSNFiDENT:AL
CGCL!Yi;ii
-
Not to be Reproduced
-
-
I
*
DATA
STANDARD .- , ,
E=I LUWUS
I
8
.
:
, [
I
1
,
' , . , '
. .
8
. ,, ,,.,,,.
4
,
I
.,
,
,, ,/',
-
56.75
I . / f .
/ J ,
,C25
(6)
. . . .
.,
,.
. ,,
I
, . . ,
.
,
,
.
. -,.,';. 8 /' . . . . . , . / I r . , : .,.'
- -.
J a n u a r y , 1972
0.74 = 56.01 ft2
.
,
6
.
.
,
.
.
.
a
,
.
,
.
,
,
4
s
, .
. :
,
,
:
.
' .
I
,
PI
.
-
.
1
1
'
l
"
, ,
b
:
,
) '
.
:
.
, , , .
,
/
. '
(7)
I
.
.
. . 1
f
..'. . . .
, > i I . I
,
,
.
. . , . I I .
.
:
j
.
. .
1 ' :
. , !
. 1
' . . , , S t
.
, . . .
8
1
: . . . . .
:
I
,
'
.
.;
:
,
,
,
1
.
,
I
,
.
,
:
I
.
I
,
cV, l b / f t 2
,
.
,
.
,
;
I
. . .
.
.
' 4
.
, I I
I
,
.
, ,
, I .
. . . . '
. .
, I .
.
.
I
,
.
. : . ,
,
i
.
. . . ,
.
i
.
, 1
J -1
. !
,
,
. . . ,
. .
.
j
,
. I
. . , . .
.
, .
; . I .
. . . ,
, . . . ,
. , , I . , .
.
i .
, I
.
,
I
1 I
Assume h l = 1 f t . The s e t t l i n g time r e q u i r e d f o r t h e heavy l i q u i d d r c p l e t s t o s e t t l e through this d i s t a n c e i s ti = (12 h l ) / v l = ( 1 2 ) ( 1 ) / 2 . 1 1 =
I
PAGE 14 O F 62
MAXIMUM ALLOWABLE DOWNFLOU
,OOOL
1
III
Then, t h e s e t t l i n g a r e a for t h e l i g h t l i q u i d p h a s e . A l , i s A1 = A-Ab
i
- PART
BOOK
DKUM SIZING
I '
5.7 m i n u t e s
Assume hh = 1 ft. Tne s e t t l i n g tine r e q u i r e d f o r t h e l i g h t l i q u i d d r o p l e t s t o s e t t l e throuoh t h i s dis'cance i s
t h = (12 hh)/vh = (12) (1 )/I -74 = 6.9 m i n u t e s
,
(8) The residence t i n e o f esch phzse based on the vo1urr.e~ o c c u ~ i e dby t h e l i g h t ar,d hetvy phases a r e
I I I 1
-!
,
Vh = hh Ah = 1 tC5.75) = 56.75 f t Z
el = 56/5.1 = 11 minutes
eh = 56.75/0.35
=
162 minutes
I
T h e r e f o r e , €1 > t1 and eh > t h and t h e r e i s no need t o i n c r e a s e the d i a m e t e r . (9)
1 I \
V1 = h l A1 = 1 (56.0) = 56 f t 3
S i n c e a s u r g e time of 25 minutes i s r e q u i r e d f o r t h e hydrocarbon phase.
I
h r = Q1(2S)/A1 = 5.1 (25)/56 = 2.28 f t = 27 i n c h e s
(10)
Drum dimensions a r e s e t a c c o r d i n g t o t h e r e c a m e n d e d p r a c t i c e s a f v e n on Fage 12. ~ o w e v e r , s i n c e t h e r e i s a l a r g e mass of vapor t o b e h a n d l e d , and o n l y a sr,ail ancunt of l i q u i d , be-jenerous i n s e t t i n g v e r t i c a l dimensions t o o b t a i n a f i n a l druir; o f r e z s o n a > l e shape. - Use a 24-inch d i a m e t e r f e e d nozz!e.
2
I C3:;FiDEKTIAL
DOCUMENT
-
Not t o b e R?-,roduced
I .C
r
Ez
LUMMUS LuMMUs
1
STANDARD
- PART - -. .-
D A T A
B O O K
DRUM nm u SI~I.M
:
+
.
hr = 1 f t s = 0.5 f t ( s e e Page 2 9 ) hv = 0.5D + 0.5(Nozzle d i a m e t e r ) = 0.5(8.5) + 0.5(2) = 5 . 3 f t hn = 0 hs = 0 hbn = O.S(Nozzle d i a m e t e r ) + 2 = 1 + 2 = 3 f t ha = 0.5 f t . h r =_2.25-ft .hl = 1 f t hh = 1 f t ldn = ii.5 i t ~ i n ~ e n t - t o - t a n g e nlte n g t h , L. Surrning up v e r t i c a l d i s t a n c e s , L/D = 1.8.
II
1
-I
L
15 OF63 P A G E 15 Januzrr: 7972'" '
= 15 f t .
Tnen
The L/D r a t i o f a l l s w i t h i n t h e recornended r a n g e of 1 . 5 t o 5.0. S i n c e t h i s i s a c a s ? o f high p r e s s u r e v a p o r - l i q u i d s e p a r a t i o n , P = 165 p s i a , none o f t h e s t a n d a r d tank s f i e s I s s u i t a b l e f o r t h e j o b . I n g e n e r a l , f o r P > 50 p s i a an L/D r a t i o o f a b o u t 3 t o 4 is favored. However, i n t h i s p a r t i c u l a r c a s e t h e drum d i a m e t e r is f i r . 2 6 a t 8.50 f t due to a vapor v e l o c i t y l i m i t a t i o n and c a n n o t b e reduced. S i n c e to f n c r e a s e r,'le drum fenst!! w i l l o n l y w a s t e drum volume, a n e c o n o m i c a l l y a c c e p t a b l e d e s i g n i s probably t h e above c n e , even though the L/D r a t i o is somewhat on t h e low s i d e . B.
Vaoor and One L i a u i d Phase I n c l u d i n g Knock-Out Dwms
A v e r t i c a l v a p o r - l i q u i d s e p a r a t o r w i t h o n l y one l i q u i d phase i s designed w i t h t h e metkod des c r i b e d i n S u b s e c t i o n A, Page 10. However,
I I
-1
1I 1 1
(a)
s s s e t t l i n ? V E - ~ o c i t i e s tnd , A l l r e f e r e n c e s t o a l i g h t l i q u i d p h a s e , s e t t l i n g t i ~ ~ and s e t t l i n g b a f f l e a r e d i s r e g z r d e d . Hence, ho=O.
(b)
The l i q u i d h e i ~ h tis e s t a b l i s h e d by The r e q u i r e d s u r g e volume. A minimin h e i g h t o f 24 inches: e x c e p t f o r knock-out drums where " L i j d i s t e c c e rrsy be reduced t o a minimrm o f 1 f t .
H u r i z ~ f l t a lS e o a r a t o r
I
A.
I
Vacor and Two Immiscible L i a u i d s h'crizontal drums a r e f r e q u e n t l y s m a l l e r t h a n a v e r t i c a l v e s s e l f o r t h e s a z e d u t y . The hezvy l i q u ' i d phase c a n b e withdrawn e i t f b e r d i r e c t l y from t h e s h e l l o r through a pot o r t r a p o u t b o o t welded t o t h e v e s s e l .
-
throuoh a n o z z l e i n t h e head. ( 2 ) f r o n b e h i n d a b a f f l e , o r (3) through a downpipe o r f i o o l n i p p l e . The c h o i c e o f t h e s e is o p t i o n a l .
(1)
F o r t h e v a p o r - l i q u i d systems conanonly e n c o u n t e r e d i n p r o c e s s a p p l i c a t i o ti g i v e n below i s used t o c a l c u l a t e t h e a l l o w z b l e vapor v e l o c i t y
fg&&-
Hence, the u s e of a w i r e mesh i n a h o r i z o n t a l drum i s o n l y j u s t i f i e d t o a c h i e v e h i ~ hl i q u i d renova1 e f f i c i e n c y , s i n c e t h e w i r e mesh does n o t r e d u c e t h e vapor space. (2)
For t h e p a r t i c l e s i z e s comnonly f o u n d i n i n d u s t r i a l l i q u i d - l i o u i d s e t t l i n g operatf;t;s, t k e f o l l o w i n g e q u a t i o n based on t h e S t o k e s Law g i v e s t h e f r e e - s e t t l i n g v e l o c i t y f o r t k e crsplets of one l i q u i d o u t o f t h e o t h e r c o n t i n u o u s l i q u i d phase: C!2rrF!CENT!AL
DOC!Jr.tNT
-
Not t o b e Reproduced
I
STANDARD--D.AJf-At-80.0K=PA&'CI1I DRUM
. [ P I A G E ~ ~O F 6 3
1 Jznuary,
SIZING
1972
I
I I
where
+)
,3%' c5
o f continuous phase, c e n t i p o i s e A
-
-
-
s
=
Heavy Phase
-. '---.
Hydrocarbons Sp.gr. @ 60°F < 0.85 Sp.gr. B 60°F > 0.85 Water
=.
Water Water Water Water
MEK
;
I
Sec-butyl alsohol Methyl isobutyl ketone Nonyl a1 coho1
The desilgn should comply with t h e requirement t h a t f o r each continuous l i q u i d phase, t h e residence t i c e , 8 , is l a r g e r than t h e s e t t l i n g time, t , needed by t h e d r o p l e t s o f t h e d i s persed l i q u i d t o s e t t l e out. Therefore, according t o the accompanying f i g u r e , el > t l =
12, minutes
Vapor
VI c h > rh =
12, minutes
---+
Light Interface tie~vy
vh
1
w h e ~v; and rh a r e t h e s e t t l i n g v e f c c i t i e s i n the l i g h t arid heavy phasz;. h s i g n i s , i-11 and h h , a r e i n f e e t .
I
w..L+fl '
Values of ks f o r
s r e ;ivel: b e l w
Liaht Phase
--\o
A5GJ
The values t o be assigned t o t h e constant kS a r e discussed on Page 6. sene trmnr, :y:rems
5'
tt8
ph = Density of heavy l i q u i d phase, 7 b / f t 3 p1 = Density of l i g h t l i q u i d phase, l b / f t 3
oc,= Viscosity
(3)
- -ie
v s e t t 1 j n g = ks ( P ~ - P ~ ) / V but ~ , not t o exceed 10 inches/min
I
hl
9
hh
V
I
I I
Ser'L:ic~
(d)
The hcr:zsn:al s e x r a t o r xay be designed t o provide a surge volsne f c r 3 2 l i ~ k : 1ic;zic phase a t t h e expense o f an increzsed vessel d i m e t e r .
(5)
See Page 36 f o r sugpested L/D ranges.
(6) See drzwings on Page 16 f o r a d d i t i o n a l design r e c o m n d a t i o n s . B.
Horizontal S e ~ a r a t o t - sw i t h a Heavy Liouid Pot
In a d d i t i o n to t h e design p r i n c i p l e s l i s t e d under Subsection A on P a ~ e15, t + e boo: design c u s t s a t i s f y these c r i t e r i a : (a)
Dcwmard flow v e l o c f t y f o r t h e hezvy l i q u i d i n t h e p o t , v s e p a r a t i o n v e l o c f t y o f t h e l i g h t l i q u i d d m p l e t s o u t o f e$
is no* ~ x c e t dv k t h e heavy9ase.
For design p u r p o s e s , m i s l i m i t e d t o a maximum o f Q inches/ein, (b) h - T (c)
- -+
- - .--..--
.
i a n ? ef u s )1 f th:
-.. .
T
t h e dthedrun diameter.
:
See drawing on Page 18 f o r a d d i t i o n a l design r e c m e n d a t i o n s .
Examole.
(1 )
-
A f t e r cooling off t o 100°F a t 25 psig, a process stream of hydmcarbon vzoor contains some condensed hydrocarbons and water. Design a horizontal s e p a r a t o r with a pot to e f f e c t t h e recovery o f t h e vapor phase and t h e s e p a r a t i o n of t h e two l i q u i d phases. Process c o n s i d e r a t i o n s r e q u i r e a 15-minute surge time f o r the hydrocarbon phase-
Given i n f a n a t i o n : W, I b / h r
Vapor Hydrocarbon Water
235.0~0 w, U ? = 45,030 I
7.50@ Wh = W t O t 2 j = 287,520
p. l b / f t 3 = 0.190 01'40.5 Fh ' 62.0
U.
CD
----u1=0.24 pt, = 0.682
.
,-,--.-. --
..
-
--
+__1---.-
(4'
-
SEPAItATOR IITSICN Wf_TtlIITAVY 1.1
& , I -
(L,,
-
I
--
--
t. PlOTES .--
(Two L l q u i d Pl~ascs Optional Wlro Mcstl)
For nozzles i n s t a l l e d on t h e s h e l l , t h e ml~rlmumdlmenslon from the tangent l i n e t o the ceritcr l i n e o f t h c n o z z l e i s
eed (see d e t a i l below)
,
( 6 + d) i n . where d n o z z l e diameter i n inches. the p o t l o c a t i o n . Ligllt Liqclitl Drawo f f
--I----
I
Thls r u l e applies also t o
1
h t " I f t h e r e I s no wire-mesh entralnment s e p a r a t o r i n t h e drum, then h t - 0 . I f a w i r e mesh i s used, nuke h t - 1 f t minimum. As f a r as t h e v a p o r - l i q u i d s e p a r a t i o n goes, a l a r g e vapor space above the w i r e mesh I s unnecessary.
s
Thickness o f t h e wlre-mcsh e n t r a i n m e n l s e p a r a t o r , r e f e r t o Page 29.
l i w = Distance from t h e maxlmum l i q u i d l e v e l t o t h e entrance o f t h e wire-mesh separator, hw=2 f t miniaum. I f an e n t r a i n hv
-
llr
ment s e p a r a t o r i s n o t used, hw=O.
t l e i g h t o f t h e vapor space s e t by t h e l a r g e r o f 1 ft, t h e req u i r e d vapor space, o r ( h t + s + hw). Baffle T Dlstance from the maximum l i q u i d l e v e l t o t h e c e n t e r l i n e o f the l i g h t l l q u i d nozzle, Thls d i s --- High Liq.Leve1 tance I s s e t t o s a t i s f t h e r e -- -. qulrement o f e l t h c r (a7 a s p c c i f l e d surgc time f o r t h e l l g l i t =r Llght l l q u l d o r ( b ) minimum submergence <' Phase t o a v o i d v o r t e x formation, whlche v e r I s c o n t r o l l i n g . Ilowever, sometimes i t i s more advantageous t o b u i l d a surge compartnlent by I n s t a l l i n g a b a f f l e as shown.
---
L -
Tanqcrt t Llne
d I
f
4
Tangent Llne
OCTATL
111, hh = S e t t l i n g h e l g h t s
--
Feed Hozzl c Arranqemcnts
9f
t h e l f g h t and heavy phases, r e s p e c t i v e l y .
Illo a Olstance from $he ilciJ_tnm o f t h e k u m s h e l l fare ICVEI, I .e., Lib. p o i n t f o r l o c a t l n g t ~ c o n t r o l l c r ,h l o = 0.5 f t mrnirnllt,
d
Feed tiozzle Throuqh Top
Feed Nozzle Through Slde
Llght Phase
h
m
Olstancc u o m the bottom o f the p o t t,* t h c ~minimtrmi n t e r f a e l c v c l I.c., t ~ pe o l n t f o r o c a t i n g the lower t a p - f o r t h e I n t e r mlontrolle:, b12.5:t mini mu^. I'
I ,
v P
..
f.1 L7
-.a
Marirn~rrnI.irl~rld
Lavol
l cvul
m a
-*
0,
W
.EE ummus /
STANDARD --
-
-
-
DATA
-
-
BOOK
DRUM --
-
P A R T 1x1
SIZING
-
T .
-.
P A G E 15 O F 6: January. 1572
-
TS = '15 minutes, as s p e c i f i e d kS = 0 . 3 3 3 s i n c e the hydrocarbon material - i s f a i r l y l i g h t ( l i g h t e r than sp.gr. of 0.85) (According t o Page 6) K = 0.35, na wire mesh w i l l be used. (According t o Page 11)
, s=0 , and hlp=6 inches
(2)
Set ht-0
(3)
The volumetric f'ow r a t e s a r e
0.5 f t (minimum).
=
3,
= w,!l6o>,J ' =235,~)0~1/[&1(0.1a)I = 20,614 f i - 3 ! ~ i n Q1 = W]/[69 p l ] = 45,000/[60 (40.5)f = 18.52 ft3/mln Gn = nn/isz ~ " 2= 3,5;;j;Gz ;&i.c;; = ;:2; fz'/aic
(4)
The allcwable vsDor v e l o c i t y i s
Calculate the minimum seamental-area
P-
AV = Qv 60 va] = 20,674/[60
(Sj
f3qw.
r e c u i r ~ro-d' (5.10)] = 67.4 f t 2
S e t t l i n q v e l o c i t y of t h e heavy l i q u i d , vl , o u t of t h e l i g h t phzse:
Therefore, make (5)
S e t t l i n g v e l c c i t y of t h e l i ~ h lt i q u i d , vh, c u t of the heavy phzse:
-~-
vh = k , ( ~ h - p l ) / v h = 0.333 (62.0
40.5)/0.622
= 10.50 -- fn/nin
in/nin (maxinun).
(7:
$
A
- * 'O L
A p r e i i n i n s r y drum diameter may be e s t f z a t e d f r o m Figure 6.
1.3 kV = 1.3 (67.4) = 8 7 . 5 , and
which aives a preliminsry d i z x e t e r of D = 10.5 f t
(a)
wit! t h i s D ptcceed t o dinensicn o t h e r distances according to drawins on P a p 1.5.
*
Fpo@ M b F 2. ( 1 0,274)
A = (a/4)D2 = ( ~ / 4 ) ( 1 0 . 5 ) =~ 86.6 f t 2 .
= 67.4 D 6 . 5 = 0.778, obtain f m z Tzble 2 the value (hv/D)
AV/A
With
Then, hv = 0.727 (10.5) = 7.63. it = 91 -6 inches. Refer now to drawing on P a ~ e18. Set
- hV =
(10.5)(12) -92 = hr
hl = 1.5 f t = 16 inches- (minimm) hl,, = 0.5 f t = @ = (minimum)
Hence,
I
D
Roundins o f f ,
@=
-
-
-
0.727.
tttt=-9z.inchss. + h i - hip -
-
(126-92-186) = X j m 3 1 1 -
f o r holdina 15 minutes of ' l i q h t licvid zbove- t ! e ( Area
A
II
-
~ = A) - AV ~ = ~86.6 ~ 67.4 ~ =~ 19.2 f t 2
- hip
up t o a height of 1 2 inches = h l
CONFiDE?4TIAL DQCPEENT
-
Not to be Reproduced
I
I-.
1
STANDARD
-
BOOK PART
DATA
EELUMMUS.
-
[ P A G E20 OF63
III
1 Januzry,
DRUM SIZINTr
--
1Si2
From Table 2: A1-lp/A = 0.0484 I
Area l e f t f o r hold-up above t h e l i q h t l i q u i d drawoff n o z z l e = 19.2
.'
.*
k
--I-
--
.*-
>J
I
(10)
1
!
Check t h a t t h e t o t a l r e s i d e n c e t ' w Total height o f l i g h t l i q u i d :
-
4.2 = 15.0 f t 2
&+-
-c
--
--.-
+-
Roundino o f f , L z 19 f t
= 18.52 f t .
L/D r a t i o = 19/10.5 = 1.81
."s-
x*7
p~ ?efi
( QL)
e oiln-oer
than k e s e t t l i n g
hr + h i = 22 + 1 8 = 40 i n c h e s .
4% inches = 4 minutes. 10 inches/min Total residence time f o r l i g h t l i q u i d , S e t t l i n g t i n e , tl =
t
,I
e l = A1 L /Q1 = (19.2)(19.0)/78.52
(
= 19.7 minutes.
T h e r e f o r e . €1 >> tl
Design o f t h e heavy l i o u i d o o t
(11)
I
Downward flow v e l o c i t y f o r t h e heavy l i q u i d i n t h e p o t . Try vp = 0.75 vh = 0,75
( 1 0 ) = 7.5 inches/rnin
P o t d i a r z t e r , JL.
Dp
= 3.9lJPh/vp = 3 . 9 l r ' . = i m i = 2.03 f t .
.Volume o f htavy phase.
Rounding o f f ,
%=
2.5 f t
% '
I
S e t hh =
Residence tiae o f t h e hezvy phase, eh = Yh/Q, = 9._82/2.02 = 4.86 m i n u t e s
S e t t l i n g time,
I
= 12 hh/vh = ( 1 2 ) ( 2 ) / 1 0 = 2.4 m i n u t e s .
1
(12)
C.
I[ II
S u m ~ r yO f The Derian hV = 7 f t - 8 i n hr = 1 f t - i O i n hi = 1 ft-6 i n hlp = 6 inches hh = 2 f t - 0 i n
b :
T h e r e f o r e , e h > tn.
Y8zor and One Liquid Phase I n c l u d i n a Knock-Out Dru.zs A h o r i z o n t a l v a p o r - l i q u i d s e ~ a r a t o rw i t h o n l y one l i q a i d phase is d e s i g n e d w i t h t h e nenetkcd d e s c r i b e d i n S u b s e c t i o n A on Page 15. However,
(a)
A l l r e f e r e n c e s t o a l i g h t l i q u i d p h a s e , s e t t l i n g t i m e s and s e t t l i n g v e l o c i t i e s are d i s r e g a r d e d . Hence: hl=O, and hr=O.
(b)
The l i q u i d h e i g h t is e s t a b l i s h e d by The r e q u i r e d s u r g e volume. A minimum h e i g h t o f 24 i n c h e s , e x c e ~ tf o r knock-out drums where t h i s listanc2 reduced t o a minimum o f 1 f t . --
C2NFl2ES'TiFL 93C;'ME:;T
-
liar ts be R ~ 7 r o d u c e d
r.2~
5e
--
-
r*
- PART
XTAND-TED' DATA
BOOK DRUM SIZING
LUMMUS
111
P A G E 27 O F 63 January, 1972
I
PROCESS STEAM DRUMS Process s t e a m drums a r e b a s i c a l l y v a p o r - l i q u i d s e p a r a t o r s . They a r e an i n t e g r a l p a r t of any u n f i r e d steam g e n e r a t i n g f a c i l i t y which u t i l i z e s w a s t e h e a t o r o t h e r h e a t s o u r c e s i n a p r o c e s s pi rrht7- The ma)^ *nttfonsMof-process-steam drums%re=
I
To sepzrate t h e stearn from the c i r c u l a t i n g b n i l z r w a t e r .
To a c h i ~ v ean e f f e c t i v e s e p a r a t i o n , s p e c i a l d e v i c e s a r e u s u a l l y provided i n t h e drum. such a s a c y c l o n e s e p a r p t o r , a w i r e mesh, o r even a s e c o n d a r y v a p o r - l i q u i d s e p a r a t o r .
I II I
*
To p r o v i d e a s u r g e volume t o dampen t h e s u r g e s caused by v a r i a t i o n s i n t h e h e a t i n p u t t o t h e system.
H o r i z o n t a l and v e r t i c a l steam drums o p e r a t i n g i n a n a t u r a l o r themiosyphon c i r c u l a t i ~ nsyst2r;l a s s o c i a t e d w i t h an u n f i r e d b o i l e r a r e d i s c u s s e d i n t h i s s e c t i o f i . O o e r a t i n ~P r e s s u r e i n Steam Drums The u s e s o f s t e a m i n a p r o c e s s p l a n t a r e s o broad t h a t i t i s n o t s u r p r i s i n g t o f i n d s t e m g e n e r a t i o n a t p r e s s u r e l e v e l s r a n g i n g from a few p s i g up t o 2,000 p s i g . The o p e r a t i n g p r e s s u r e l e v e l a f f e c t s markedly t h e steam drum d e s i g n , mainly due to mechanical and s t r e s s c o n d i d e r a t i o n s . Hiph P r e s s u r e Steam Druns ( P > 450 p r i g ) The d e s i g n of high p r e s s u r e s t e a m drums (P > 450 p s i g ) s h o u l d be l e f t to experienced s t e m d r m d e s i g n e r s ; e - g . , Combustion E n g i n e e r i n g , Babcock and Wilcox, Borsig b b H , e t c . The respons i b i l i t y OF t h e p r o c e s s e n g i n e e r i n t h o s e c a s e s i s l i m i t e d t o s p e c i f y i n g t h e f o l l o w i n g p r o c e s s i n Fornation:
*
Heat i n p u t t o t h e w a s t e t e a t r e c o v e r y exchanger and t h e r e q u i r e d steam g e n e r a t i o n pressure.
* Drun! w a t e r h o l d i n g ttme a t normal cperat;ng: l e v e l .
* Drcm s u r s e c e p ? c i t y , i . e . , t h e w a t e r volu-e above t h e n o r a l o c e r a t i n o l e v e l .
The
f o l l o w i n g t a b i e i s r e c c m e n d e d f o r s e l e c t i n g t h e s u r g e voluce:
Note:
STEAM CAPACITY, 1b / h r
SURGE. 1 b Hz0
Up t o 30,000 50,000 75,000 100,000 & o v e r
2,000 2,500 2,750 3,000
ft3 18GO p s i c
SCRSE VCtV%.
650 c s i c
40 50 55 60
M 62 68
:
74
The above t a b l e is g e n e r a l l y a p p l i c a b l e t o bundle-type exchangers. However, i n t h e c a s e o f h e z t e r s w i t h a l a r g e v o ? m / s u r f a c e r a t i o ( e - g . , c o i l h e a t e r s ) t h e f i n a l drm dirnensi'ons s h o u l d s a t i s f y Vdm 3 1 . 2 t o 1.4 (Volum of Exchanger Return P i p i n g ]
+
Type o f c i r c u l a t i o n and c i r c u l a t i o n r a t i o , which is t h e r a t i o o f t o t z t w a t e r f e d t o boi 7 e r / s t e x n g e n e r a t e d . S p e c i f i c a t i o n s f o r s t e a m d r y n e s s . T h i s is a l s o r e l a t e d t o t h e d e s i g n o f t h e blokdown s y s t e m r e q u i r e d to m a i n t a i n a f i x e d d i s s o l v e d s o l i d s l i m i t i n t h e c i r c u i t . The above i n f o m a t i o n s h o u l d b e e s t a b l i s h e d w i t h t h e a s s i s t a n c e of t h e a p p r o p r i a t e personnel i n P r o j e c t Engineering,who w i l l a l s o c o n t r i b u t e t o mechanical s p e c i f i c a t i o n s and g u a r a n t e e s to b e met by t h e vendors. Low P r e s s u r e Steam Drums ( P
< 450
osia)
Lcw p r e s s u r e s t e a m drums can be h o r i z o n t a l o r v e r t i c a l , w i t h one o r more down p i ~ e sgoing t o t h e w a s t e h e a t b o i l e r , and u s u a l l y h a v i n o s e v e r a l r e t u r n s t o b r i n g back t h e t r o - p h a s e m i x t u r e i n t o t h e drum. To i n s u r e s a t i s f a c t o r y s o e r 2 t i o n . t h e Steam drum must h e provided w i t h i n t e r n 6 1 5 t h a t w i l l s e p a r a t e t h e m i x t u r e of s t e a m and w a t e r r e t u r n i n s t o t h e drum frcm t r ~ ew a s t e h e a t exchanger.
I I
LOW
PqiSSURE S7EP.M
WASTE HEgT EOILER
DRUM
r*
STANDAR3
BOOK
DATA
LUMMUS
- PART
I11
DRUM SIZING
>
PAGE 23 O F 63 J a n u a r y , 1972
The i n t e r n a l s may be a r r a n g e d f n t h e manner shown i n t h e f i g u r e on t h e ~ r e v i o u spage t o promote optimum v a p o r - l i q u i d s e p a r a t i o n . Desiqn P r i n c f p l e s f o r H o r i z o n t a l Steam Drums 1.
A v a p o r i z a t i o n r a t e f o r t h e u n f i r e d b o i l e r o r exchanger i s u s u a l l y e s t a b l i s h e d from p r o c e s s c o n s i d e r a t i o n s . In g e n e r a l , 20-30% v a p o r i z a t i o n by w e i g h t o f t h e w a t e r f e d t o t h e b o i l e r may be assumed. t
2.
The w a t e r hold-up time i n t h e drum is a b o u t 10-15 minutes based on f e e d w a t e r r a t e . In c a s e s x b r e t h e de?i*:cry cf b o i l e r f e n d w a t e r i s re?ativc!v .zssu?ed, a hold-up a. Taw a s 5 m i ~ u t e s may b e used. The feed w a t e r r a t e is equal t o ( s t e z m r a t e +-blowdown).
3.
The hold-up volume c o r r e s p o n d i n g t o t h e volume. This hold-up volume f s d e f i n e d t h e p o i n t o f breaking t h e l i q u i d s e a l s , assumed t o o c c u r a t a d i s t a n c e o f 0.1 D
4.
An VD r a t i o of 3-5 is r e c o m e n d e d .
5.
A s u r g e c a p a c i t y is added t o t h e hold-up volume t o d e t ~ r m i n et h e maxTmrn l i q u i d l e v e l . f o l l o w i n g t a b l e provides t h e r e c o m e n d e d s u r g e c a p a c i t ' e s :
*
1
I
I
w a t e r hold-up t i m e occupies 40% o f t h e t o t a l drum a s t h e volume between t h e normal ~ p e r a t i n gl e v e l and i . e . , t h e minimum l i q u i d l e v e l . The break o f s e a l s i s from t h e bottom o f t h e drum.
STEA.hi CAPACITY, I b/hr
SURGE, l b H20
Up t o 30,000 50,000 75,000 100,000 & o v e r
2,000 2,500 2,750 3,000
The
SURGE VOLUME, ft3
I
I
35
-
47 52 57
Note: The above t a b l e i s a e n e r a t l y a p p l i c a b l e t o bundle-type exchangers. Ho.niever, i n t h e c a s e o f h e a t e r s w i t h a l a r c e vo'lune/surface r a t i o ( e - g . , c o i l h e a t e r s ) t h e f i n a l drum dimensions s h o u l d s a t i s f y Ydrum )/ 1 . 2 t o 1.4 (Volume of Exchanger + Return P i p i n s )
1 6.
I
I
Tie v a p o r v e l o c i t y i n t h e s p z c e l e f t rbave t h e r a x i n m l i q u i d l e v e l shculd s z t i r 7 y i h a t e j t h e r ( a ) H o r i z o n t a l vapor v e l c c i t y , based on 1/2 o f t h e vapor f l o w , v~ < 0 . 3 5 / T ~ ~ - p , , ) ii ~n ~ f t / s e c , f o r d r u m w i t h impi ncjenent b a f f l e s .
OR [b) V e r t i c a l vapor v e l o c i t y l e a v i n o t h e w a t e r s u r f a c e a t tkn n o r m ~ io p e r a t i n , " l e v e l does n o t exceed vy 1 f t / s e c , f o r low p r e s s u r e d r m s (P < 100 ps:'q) w i t h o u t b a f f l e s .
<
7.
I n G r n a l s a r e i l l u s t r a t e d i n t h e p r e c e d i n g f i g u r e . I n cases where the stem d r y n e s s is n o t e s s e n t i a l , a s i n a r e b o i l e r h e a t exchanger, t h e impingenent b a f f l e may b e e l i m i n a t e d i f P < 100 p s i g . For high s t e m q u a l i t y i t is r e c o m n d e d to d e s i g n t h e d r ~ mw i t h a w i r e mesh.
Desian P r i n c i o l e s f o r V e r t i c a l S t e m Drums V e r t i c a l s t e a m d m can b e d e s i g n e d a c c o r d i n g t o t h e p r i n c i p l e s o u t l i n e d p r e v i o u s l y f o r h o r i z o n t s l s t e a m drurm w i t h t h e e x c e p t i o n o f the impingenent b a f f l e p l a t e which is n o t used. h w e v e r , t h e upward v a p o r v e l o c i t y t h r o u c h t h e drum s h o u l d n o t exceed
and
v = 0.20 ~ p l - p v ) / p y , f t J s e c ( f o r drums w i t h o u t a w i r e mesh) v = 0.35 4 p l - p v ) / p v ,
f t / s e c ( i f a w i r e mesh is used)
R e f e r t o t h e f o l l o w i n g f i g u r e f o r a d d i t i o n a l d e t a i l s and minimum dimensf ons.
I t i s i m p o r t a n t t o mention t h a t i n c e r t a i n soecia'l a p p l i c a t i o n s , s u c h a s i n t h e v e r t i c a l d i l u t i o n steam drums f o r e t h y l e n e p l a n t s , a s m a l l amount of c a u s t i c is added t o t h e watrlr i n t h e drum to p r e v e n t c o r r o s i o n . However, s i n c e i t is t h e n c r i t i c a l n o t to pass any c a u s t i c - c o n t a i n i n g mist u r e o u t w i t h steam. s p e c i a l d e - e n t r a i n m e n t d e v i c e s , such 2s c y c l o n e s e p a r a t o r s and c o r r u q a t e d b a f f l e p l a t e s , a r e i n s t a l l e d a t t h e t o p o f t h e drum. I n a d d i t i o n , a secondzrjl v a ~ o r - 1i q u i d s e p a r a t o r may be n e c e s s a r y , e i t h e r i n s t a l l e d i n t h e same s h e l l on t o ? of t h e primary s e p a r a t a r o r b u i l t reco.mendea when s e v e r 2 1 s t e m a s a s e p a r a t e drum f u r t h e r down t h e l i n e . T h i s l a s t a l t e r n a t f v e l i n e s f r o m o t h e r s t e a m drums may be t i e d i n t o a s i n g l e secondary s e p a r z t o r . CONFIDENTIAL 00C3XE3T
- Not
t o be Reproduced
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II
IPAGE:
1
24 o f 63 DATE: Jan.
. 1972 1
DRUM S I Z I N G
Vertical Steam Drum i
t
!
Steam
I
i:
/
6 i n . wire mesh o r other appropriate de-entrai nment dew ce
I
B u t not l e s s t h a n 3 f t
,3 Max. L i q . Level -----C a n t i nuous
Blowdown Lin
f f
I
i
/
'Jol ume between normal and m i n i m u m level is acproxirnately 402 the drum volume,
------
7 J 2
Intermittent B l owdown Li ne -
-
*
6 i n . Ninimum o r s e t by standard p r a c t i c e f o r l e v e l control instal lation --
1r
*
STANDARD
DATA
t
I-
Examole.
11
8 0 0 K
- PART
)PAGE
111
DRUM SIZIIIG
1.
A b a f f i e d horizontal steam drum, i s required f o r a waste heat steam generat:'nc c i r c u i t with a capacity of 110,000 _lb/hr of s a t u r a t e d steam a t 70 psia.
~t p=70 p s j a , p l = 58.8 1 b / f t 3 and
pv =
-
I
+
I?
(Blowdown R i t e )
i
I
Equivalent water volume,
I
Choose 10 minutes of hold-un based on feed w l t e r r a t e .
VHzo = 10 ( 3 2 . 6 )
=
326 f t
Then, t h e d r ~ r gha;ci-up
is
3
Assuming t h i s i s 40% o f t h e t o t a l drum volume, vdrum=
326/0.40=815
ft3
And t h e corresponding drum dimensions a r e . f o r an L/D = 4
D
= 6.38 f t ; round o f f t o D = 6.5 f t L = 4 (D) = 4 (6.5) = 26 f t Drum cross-sectional a r e a , A = 33.2 fti
3.
Volume of H20 atove the minimum l i q u i d l e v e l i s Vw = Y H ~ c ) f Surge V O ~ L I ~ E . . :, For
2 st233
r 2 r ~of 110,000 l b / h r t h e surse vclume i s 57 ft'.
men,
-
a c e r t a i n vclune of t h e drza require2 t o hold t h e s e an e f f e c t i v e a r e a , A 1 . H ~ n c l ,t h e r e i s
383 f t ' ,
CC-rez;cndisz b
Maxi nun Wzt=.r ie.ie?
f+ i gn t Necessary Hol a 383 fi3
.Min i z m Water Level
I
. The
de3d area a t t h e bottom of t h e drum below the minimum l e v e l i s , f r c n Table 2 , 0.052 ( 3 3 . 2 ) = 1.73 f t 2
. Total . Area
c r o s s - s e c t i o n a l a r e a of 1 iauid a t t h e maximux; 1 i a u i d l e v e l : "- --. . A l j q u i d = 12.7 + 1.73 = 16.4 ft'
-
l e f t f o r the vapor flow:
AV
= 33.2
- 16.4
= 16.8 f t 2
From t h i s , s u b t r a c t t h e vapor a r e a behind the b a f f l e , i .e.,
I
AB.
based on an area r a t i o b ' f ~ A B / A = 0.1096 foi- a B a f f T e placed at (;/6)D f n n t h e w a l l
(See Table 2 ) . .-
CONF!DENTIC\L
WC'JXEI:T
-
I
I
0.1611 l b / f t 3
Steam r a t e . WS = 110,000 l b / h r ,
WfiZ0 = WS
2.
25 0 ~ 6 3
D e c c L r r , 1471
Not to be Reproduced
--
STANDARD
DATA
BOOK
DRUM
I
!
Vapor space = 16.8
. Check
I
-
- PART
111
SIZING
] P A G E 26 O F 6 3 December, 1975
-
1.82 g 15.0 f t 2
t h e horizontal vapor v e l o c i t y only, s i n c e a b a f f l e i s used.
(
~
~ = Qvapor/Vapor ) ~ ~ Space ~ = ~94.8 ~/ I 5 . 0l =
(vH)allowab7e= 0.35*1(58.9
-
b. 32
tt/sec
0.1611)/0-1611 = 6.63 f t / S e c
The vapor v e l o c i t y i s OK. 4.
B a f f l e design
. The
1
?
1
k '1+-----
d i s t a n c e d should be d = 1/4 f D ) = 114 (6.5 x 12) = 20 inches
. For
the I e n ~ t n , 1 = 26
-
[ ( 2 ) ( 2 0 / ? 2 ) ] = 22 ft-6 i n
. Several notches t o k c u t a t t h e bottom edge t o f a c i l i t a t e t h e
. For
a r a t i o (c/D) = 1/6,frorn Table 2
And f o r t h e d i s t z n c e a ,
(b/D) = 0.7455.
l i q u i d ?assage.
Then, b = 4 ft-10 i n .
EE
STANDARD LUMMUS
DATA 0RUI-I
BOOK
-
PART
PAGE
O F 62 January, 1972
Iii
SIZING
27
A U X I L I A R Y EQUIPMENT AND DRUY INTERNAL5 Vapor
Wire-Mesh Entrainment S e ~ a r a t o r s
, I
An impingement s e p a r a t o r i s a mechanical device used t o achieve t h e e f f e c t i v e s e p a r a t i o n o f l i q u i d d r o p l e t s from a vapor-liquid mixture by passing t h e mixed phase stream through it. One o f t h e most v e r s a t i l e impingement separat o r s f s t h e k n i t t e d wire mesh, which has a high l i q u i d removal e f f i c i e n c y (+ 99%) combined with low pressure drop.
C r i t e r i a f o r Usage In v e r t i c a l drums, a wire mesh allows higher vapor v e l o c i t i e s than those allowed without t h e wire mesh. Therefore, whenever t h e vapor flow c o n t r o l s t h e s i z e of a v e r t i c a l drum, i t is economically advisable t o use a wire mesh t o reduce t h e drum s i z e . An analogous reduction does not r e s u l t f o r horizontal drums. In a d d i t i o n , t h e use of a w i r e mesh may a l s o be d i c t a t e d by the high l i q u i d removal e f f i c i e n c y required In c e r t a i n processes. Removal e f f i c i e n c i e s higher than 98% can only be obtained with a wire mesh.
The vapor v e l o c i t y thmugh t h e wire mesh d e t e n i n e s i t s c z p ~ c i t yf o r e f f i c i e n t l i q u i d r e m v a l . As discussed on Page 11, t h i s vapor v e l o c i t y i s d e p e n d ~ n ton a constiint, K, according t o VE
I n przctic.,
= K J C F ~ - P ~ ) / Pf t~/ s, e c
t h e values of K i r e r e s t r i c t e d t o t h e des:gn ranpe s h s u ~:n t ! e f i g u r e below.
I
..'
I f t h e v e l o c i t y .through the' wire mesh I s t o o low. mlximum coalescence w i l l not occur. I f t h e v e l o c i t y i s t o o high, coalesced l i q u i d w i l l be re-entrained from t h e wire mesh back i n t o the vapor.
2
I
-
A value o f K = 0.35 is recornended f o r desianina drum w i t h a wire merh.
CONFIDENTIAL IXCUMENT
- Hot
t o be Re7roduced
*
I
.
*-&--.
k
2
7
-
a-
,
>..,
--
E*! C.
DATA
STANDARD ,,,,US
,-a-3e1Lu:-:u
-
------
-.--
-
---.- .---
-
- PART
BOOK
d .
--
PAGE 28 OF 63 January. 1972
111
DRUM SIfIfiG
Limi t a t i o n s
*
In general wire-mesh pads a r e not used i f t h e r e i s a chance o f s o l i d s being d e p o s i t e d , s i n c e . t h i s might lead t o clogging of t h e wire mat. This s i t u a t i o n a r i s e s when undue q u a n t i t i e s o f r u s t , s c a l e , e t c . a r e present i n t h e f l u i d and a l s o when a hydrocarbon l i q u i d i s t o be separ a t e d a t a temperature a t which cracking may occur under t h e c o n d i t i o n of long residence t i n e , a s p r e v a i l s i n t h e wire-mesh mat. However, s p e c i a l types of wire-mesh pads a r e a v a i l a b l e f o r d j r t y s e r v i c e s 2s djsryssed under "Specifications" i n t h i s s e c t i o n .
D.
Pressure Droo The t o t a l pressure drop through a wire mesh i s given by AP = 62.4 ( A P ~ + AP1 ) / p l ,
inches of h o t 1 iquid
APV i s t h e pressure drop of the vapor passing through a dry w i r e mesh and i s c a l c u l a t e d as f o l l ows : APV = 0.0236 f pv t v2
1,
where
APV = t = pv = v =
vv f
Pressure drop, inches of water Thickness of t h e wire-mesh pad, inches (normally 4-6 i n c h e s ) Vapor d e n s i t y , 1 b / f t 3 Vapor s u p e r f i c i a l v e l o c i t y , f t / s e c = Vapor v i s c o s i t : ~ , cp = F r i c t i o n f a c t o r given below
1 .OJ
1 1
: _
,.
_
t
_
I
t - - - - ~ ~ - r + ; : ' i
,
---+-
%;4;:
1
a
0 .-- 6 . .- ", _ ! - L -----Ll_-
i
I
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'
.
,
,
,
,
,
:
,
t-
-
-
4
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-
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,
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.i-A
.-
~.-,
A . -
i i
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ic I
I
2
1
4
8 1 0
6
20
60 80 100
40
pvv -
I i
uv
I
I
A P l i s t h e pressure drop of the vzpor dye t o t h e l i q u i d hold-up i n t h e wire mesh as given
i n t h e graph, 0.4 , . - A . - :- ,.. ~
where
AP1 = Pressure drop, in. o f water
=c--;P~
- -
tiquiddenbi&,
lbjft?,
:-
.
~--;.-
=-
- L z ~ + .:.
;--yz-z7
--:z=Fl
, hP1
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-
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7
.
.
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- -
0.2
0.3
0.4
0.5
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DOCUMEliT
-
Net t o be Reproduced
-
.
Ez
j
.
.
..-.
STANDARD
.
-.
.
:
DATA BOOK ORU4X SIZING
-
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.-". ->-,+
..,,.-
P A R T III
,
.
-
2,
'--"U
& .
) P A G E 29 O F 6 3 ( Jacuary, 1575
]
Thickners
[E.
I
LUMMUS
'
A pad thickness of 4 t o 6 inches is s u f f i c i e n t f o r most vapor-liquid separzsion a p p l i c r t i o n s , with a r e s i d u a l entrainment estimated as l e s s than 20 ppm.
'
When t h e l i q u i d entrainment c o n s i s t s o f a very f i n e m i s t o r fog, as may occur when l i q u i d d r o p l e t s condense from 3 s a t u r a t e d vapor, a pad thickness o f 1 t o 2 f e e t m y be required. These r a t h e r t h i c k pads may be made with a very t h i n wire. In specizl cases where l i q i l i & such as s u l f u r i c a c i d , glycol , e t c . a r e handled, f i b e r g l a s s elements sandwiched between wiremesh elements nay be required t o achieve high e f f i c i e n c y of jiqui: re~o';.ai.
I
To h e l p i n s p e c i f y i n g connnercial wire meshes, t h e following t a b l e sumnzrizes tlie p r o p e r t i e s of a v a i l a b l e standard types. Approx.Weicht persqftfor 4 in.tk.oad,lb
No m a 1 Remval Efficiency,%
Approx.Surface persqftof pad
Approx-Mesh Density,lb p e r cu f t
4.3
38.3
12.9
97.2
99.9
4 -3
35.7
12.0
97.4
99.8
28.3 21.6 22.0
9.5
98.0 99.0 99.0
99.5 99.0 98.8 plus]
3.1 2.4 *2.5
*
Percent Voids
7.3
5.0
Typic21 ADD^ i c a t i o n s For very high efficiency. Relatively clear, s e r v i c e and m t e r i t e v e l o c i t i e s General p u ~ o s ? . For s e r v i c e s c r ~ r s i n i n g solidr or d i r j mater
Herringbone Crinkled Wire Mesh, 6 inches Thick
For s p e c i a l c r s e s t h e p e r c e n t voids c r n be derrezsed i f desired. The above i s bzsed cr, wire having a diameter of 0.911 inches; however, f o r s p e c i a l a p s l i a t i o n s wire d i a x t e r s 5f 0.936 inches a r e sometimes used t o achieve low pFn residual e n t r a i n m n t .
I
.,
-
far
As p a r t of t h e s p e c i f i c z t i o n f o r a w i r e r e s h , t h e przc?ss e ~ r ; i n e e ri s rec:cns;zie ing t h e f o ? lowi nc:
S;PC:TY-
--
(1 ) Type of a r e r e y > red. ( 2 ) m m ~ a th~hknx?s_s d r e s i r e d for_ the sexvice, (31 Recuired c r o s s - s e c t i o n z i a r e a and dimensions f o r the pad. I f t h e a r e ? i s i r c r s ? r s P , the? chick t h a t t h e vapor v e l o c i t y throuch t h e mesh i s nor'be?cw m i n i n ~ i(A = 0.151. ( 4 ) Location o f t h e w i r e m s h . Locating t h e mesh i n t!!e d r m he2d i s j u s r i f i e d i f 3 i e savings i n mesh a r e a and drum h e i g h t o f f s e t t h e c o s t of a d a i t i o n a i su?port. ( 5 ) C r i t i c a l i n f o m a t i o n a f f e c t i n g t h e mechanical design o f t h e mesh pad, Fcr i n s t a x e , ' wire-mesh pads f o r ccnpressor s u c t i o n dl-~ms should be p r o c e r l y secured ti^ F r F v e n t ?;an's c z r r y i n g o v e r s n a l l l ~ o s ep i e c e s o f t h e mesh pad int:: t!!e mLqlnery. Ir: eL:y:ene t h e supporting arrancement shown i n Drming No. D2.357-0, Page 30, has beer, us& Z a m i d t h i s problem. I t i s recornended t h a t LTC-HED be consulted on t h e mec5azical d e s i ~ r ,of wire-mesh supports f o r c r i t i c a l s e r v i c ~ s .
I
..
I
I
The above information is t o be given on t h e vessel sketch.
Feed and Out1 e t Nozzles A.
-
Sizins r -
-%a s i z e s a.f t h e i c l e t and o u t l e t nozzles a r e n o n a l l y t k s m e as those ~5 the-wnner;:r,c process l i n e s . However, t h e r e a r e cases where t h e o u t l e t nozzle s i z e may have t3 be l a r s e r than t h e l i n e s i z e t o avoid v o r t e x formation. In these c a s e s , t h e t r a n s i t i o n p i p e canrezting t h e o v e r s i z e d o u t l e t nozzle with t h e s m a l l e r s i z e process l i n e is t h i r t y nozzle d i a x t f r s long (30 d ) ht_not f9__excee_dJO f e e t . If t h e i n f o n a t i o n on l i n e s i z e s i s not a v a i l z b l e wren t h e v e s s e l s k e t c h i s prepared, t h e process e n g i n e e r must s p e c i f y prel iminary nozrle s i z e s s o t h a t t h e c o s t i s r e f l e c t e d i n t h e vendor's q u o t a t i o n . To avoid a p r i c e i n c r e a s e over t h e c r l c i n a l The q u o t a t i o n , t h e s e preliminary nozzles a r e n o n a l l y s i z e d l a r g e r than t h e f i n a l noiz!es. following recomnendations a r e used f o r preliminary nozzle s i z i n g only:
-.
Licuid Lines
I
-
-
*
- I
I
Liauid feed, v i n l e t C 10 ft!sec CONFICENTIAL DOCUMEYT
7 -
-
Not t o be Reproduced
c w a NCL :r
3 sq
I
STANDARD
DATA
B O O K
-
I P A G E 1.1
PART
DRUM SIZING
Dezs-zr-.
O F ~2 1575
Liouid drawoff such as from a v a p o r - l i q u i d s e p a r a t o r o r a l i q u i d - l i q o i d s e t t i e r . Voutlet
Q
-
6 ft/sec
Check f o r v o r t e x f o r m a t i o n a c c o r d i n g t o Page 32. O u t l e t Vapor Lines v < 6 i ) / c
1
, f t / s e c where pv is i n 1 b / f r 2
i
Mixed Feed Lines Drums w i t h o u t a w i r e mesh vmixed f e e d
< 45/&,
ft/sec
Drums w i t h a w i r e mesh vmixed f e e d , ( ' 6 0 / G , where
p, = pl A + p v ( l - A ) , l b / f t 3 1 = Q1/(Q1
+
Qv)
Q1 = L i q u i d v o l u r e t r i c flow r a t e Qv = Vapor v o l u m e t r i c flow r a t e
( I
, fi3/sec
V e r t i c a l Drum Noizle l o c a t i o n s h o u l d be e s t a b l i s h e d based on t h e r e c c m e n c a t i o n s given i n 5': :e~:'cr; retkcds . .. . . If n x r e than one f e e d n o z z l e i s n e c e s s a r y i n 2 vapor-1icui:d s e ~ a r a t o r , cor.s::er e z z c : ng ~ n vr e r t i c 2 l d i s ~ a f i c ebetween t h e n o z z l e s a s much as possib;e by o r i 2 n ~ : n ; :-.E rrr:::~ a t an a n g l e and l o c a t i n g t h e n a t t h e s z n e e l e v a t i o n .
I
I
, ft3/sec
Lccation
0.
(
ft/sec
-
-
Tie o u t l e t f o r l e v e l i n s t r u m e n t s a r e mounted on t h e same s i d e o f t h e di-2;; as L-5 IEST n o z z i e t o avoid i m p i n g e s e n t o f t h e f e e d on t e e l e v e l i n s t m c . - n t i t s e l f w + i c rt, tzz.!se t h e i n d i c a t i o n of f a l s e l e v e l s . ,
(2)
Hcrirontal D r m f i e primary c r i t e r i o n t o b e . s a t i s f i e d i s t h a t i n l e t and o u t l e t n c z z l e s s h s u l i >r i c c e t e d as f a r a p a r t h o r i z o n t a l l y a s p o s s i b i e , w i t h i n Lbe 1 imi t s o f m e c h a n i c ~ l cons:rx:zizn. For small s i z e f e e d p i p e s , t h e i n l e t n o z z l e t o a h c r i z c c k l drurr, hzsd'linc 2 v s : c - - 1 i c ~ i d m i x t u r e u s u a l l y ends i n a 90"-bend i n t h e vaoor s p a c e above t h e l i c u i d l e r e ? , =;:rting towards t h e nest- end o f t h e drum. A l e s s exnensive a i t e r n a t i v e f c r l a r o e f e c r ;izes riy be a d i p l e g i n t o t h e drum above t h e l i q u i d l e v e l , w i t n t ~ ecd e c z ~ 3 2 d2 ~ a6 ?::zr: czt a t o f t h e p i p e w a l l . The minimum notch a r e a s h o u l d be t h e pice cross-sections: ar-ez.
I
I f t h e h o r i z c n t a l drum h a n d l e s o n l y two l i q u i d pheses, t h e feed n o z i l e s h o u l c h 2 v f t h e g e o m e t r i e s d e s c r i b e d i n the drawing on Page 7.
C ~ Eo f
I
II I
I
Extending t h e l i q u i d o u t l e t n o z z l e i n t o t h e drum i s an o f c t n used p r a c t i c e f c r hyerscarbon phase o u t l e t n o z z l e s a t t h e bottom o f h o r i z o n t a l d r u r s i n which wz:or czr, scrs-ul a t e . The o u t l e t n o z z l e s h o u l d then extend a minimum of 4 i n c h e s above the hi;? w z r e r l e v e l o r a minimum o f 4 i n c h e s above t h e bottom of t h e drum i f a w a t e r se?zra:izr p c t i s a t t a c h e d t o t h e drum. 7-
1
-* -*. .
I n p r o c e s s drums o p e r a t i n g c o n t i n u o u s l y or i n t e m i t t e n t l y a t h i ~ ht e m p e r a t u r e s , Lye u s e o f a w a t e r - o i l s y s t e m i s n o t reconunended, because t h e h o t o i l G~FE-deposited-*mwtber-= l a y e r w i t h calami t o u s r e s u l t s . CONF!DE!.ITIAL
DOCUMENT
- Not
t o be Reprcc'uc~d
E<
STANDARD
DATA
LUMMUS
BOOK
-
P A G E 32 O F £ 3
P A R T 1x1
Gec:mer,?975
DRUM SIZING
Drains and Vents In g e n e r a l , v e n t i n g and d r a i n i n g s h a l l be accomplished through v e s s e l a n d / o r equipment connect i o n s . Drains and v e n t s may be l o c a t e d i n overhead o r bottom p i p i n g p r o v i d e d t h a t v a l v e s o r b? i n j s a r e n o t l o c a t e d between t h e d r a i n o r v e n t c o n n e c t i o n s and t h e drum. Drains and v e n t s which a r e not valved s h a l l be plugged only. Drains s h a l l a l s o be provided on t h e low p o i n t s o f a l l p r o c e s s l i n e s .
I
Drt-i:i; e;;;p:;j~c; i n t s o p e s rect;tar'gs sha'l r e - p i n ; : ~ 2 i;rtls ;:.;ye :he t;; sf th.: d r a i n r e c e p t a c l e , and t h e d i s c h a r g e s h a l l be v i s i b l e from t h e l o c a t i o n o f t h e d r a i n v i ' v e . .
II
I
V e n t s - s h a l l a l s o be provided on high p o i n t s o f p r o c e s s l i n e s , i f deemed n e c e s s a r y . A.
Drain S i z e s .
5.
Vent S i z e s .
Establish drain s i z e s as per t h e following t a b u l a t i o n , based on t h e drum voluine:
Vessel Volune, cu f t
Drain S i z e , i n . *
50 and u n d e r 50 t o 200 200 t o 600 600 t o 2500 o v e r 2500
1 1-1 ,!2' 2
Once t h e d r a i n s i z e h a s been determined, t h e s i z e o f t h e v e n t can be o b t a i n e d f r o n t h e t a b u l a t i o n given below f o r drums operating a t e s s e n t i a l l y atmosaneric ~ressure.
3
4
Drain S i z e , i n .
Vent S i z e , i n .
1 1-1/2 2 3 4
3/4 1 1-i/2 2 3
F s r d r u m o p e r a t i n g a t P > 1 a t g , t h e v e n t s i z e may be c a l c u t a t e d from , d = CK where d = Vent d i a m e t e r , i n c h e s 4 = S h e l l + heads s u r f t c e a r e a o f t h e drum, f t 2 P, o r i a -C C = A c o e i i i c j e n t r s l a t e d t o t h e o p e r a t i n o p r e s s u r e a s follows: IE-SC 9.2:
-
Crc*x O f f Nozzle S i z i n a -
-
60-290
0.?6
200-7C3
0.22
Vottex 5r??kers
The fom.ation o f a v o r t e x ir: 5 I r s r l s s t r ~ mc s s t be e v o i c e i b s c e v s e 2 vcrte?: c u ! d i and vf b r z c i a n s . ?osr ;!:-ip performance, dzzaae t o the ;;uzp, p m d u c t c o n t z n i n z ~ on A . Vor'mx Formation
CE~;SS
The niajor f a c - r a f f e c t i n g v o r t e x f o r z a t i o n is t h e l i q u i d head above L+e t o p o f t 5 n~o z z l e . This l i q u i d head i s c a l l e d s u h m r c e n c e . Other minor f z c t o r s a r e , t h e l o c a t i o n o f t k ~n o z z i e , v a r i a t i o n i n l i q u i d l e v e l , d i r e c t i o n o f i n l e t vzpor, etc. Sukmroence, S , is the distznce f r o n 'tie low l i q u i d l e v e l t o t h e c l c s e s t edge of t h e draw o f f r,ozz'le.
-- -
- 1 -
-
Low - -Liquid - - -Level - -
-------Low L i q u i d
--
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1 Draw Off Nozzle The minimum s u b m r g e n c e (head) needed t o o b t a i n t h e d e s i r e d fiow of l i q u i d throuch a n o z z l e i s o b t a i n e d from F i g u r e 7 on Page 63A. Tnis f i g u r e i s e s s e n t i ; a l l y a f l w nap which d e s c r i b e s t h e f o l l o w i n g flow r e o i n e s .
*
In drums with b u i l t - i n c c m p a r h e n t s , t h e combined t o t a l d r a i n a r e a s h a l l equal t h a t -of t h e s i z e s p e c i f i e d i n t h e t a b u l a t i o n . I f t h e drum d e s i g n i n v o l v e s t h e u s e of a p o t , t h e p o t w i l l have a f u l l s i z e d r a i n c o r r e s p o n d i n g tu the,vessel d i a w + ~ ~ d , l 3;C ~ t h e drum w i l l a l s o have a 1-1/2 i n c h d r a i n . CO::FIDE!iTIAL
D3CU>?ENT - Not t o be Re2roduced
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STANDARD
D A T A B O O K DRI" STZING
-
P A E T I!:
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I n Zone I,S e l f - V e n t i n a Pipe, the p i p e e n t r y acts as a c i r c u l a r w e i r and the l i q u i d fiws down t h e p i p e w a l l s s u r m u n d i n g a vapor core througn which any e n t r a i n e d vapor mzy escrze. Designs i n t h i s zone r e q u i r e very low hezds. Zone 2 i s a T r a n s i t i o n Recion where the vazor and the l i q u i d a r e b e i n g drawn down i n t o tke nozzle by a v o r t e x i n g a c t ~ o n - a n d t + e v z r c r may n o t have a chance t o f u l l y disengage from t + e l i q u i d . I t i s unsafe t o design i n t h i s r e s i o n unless an e f f e c t i v e v o r t e x breaker i s used. I n Zone 3 , described as a L i o u i d - F i l l e e 2::e. enough head i s p r o v i d e d t o prevent the vapor from r e z c h i n g the n o z z l ~ . The nczz;e z c x . as a f u l l y submerged o r i f i c e and a h i @ head i s r e q u i r e d t o o v e r c m e the entrance l o s s in: tne nozzle. Draw o f f n o z z l e designs i n Zones 1 and 3 do n o t r e q u i r e vortex breakers.
The vsc o f Examole:
Fit-re ?
w i l l be i l l v s t r a t o d i n
:"ffo!!r.,!in~
everp_?ie.
A f l o w o f 1000 GPM ( ~ a x i r n u d i sr e < u i r e d through a nozzle l o c a t e d a t t h e bcf:x c e n t e r l i n e of a process vessel. k i t h the a i d o f F i g u r e 7, pase 6 3:. select the p o s s i b l e n o z z l e s i z e s and p i p i n g arrangeaents t h a t a r e acceptable.
Locate t h e f l o w (G?M) and move v e r t i c z l l y uswzrds t o i n t e r s e c t the v a r i o u s drzw o f f nozzle diameters u n t i l t h e minimum a v a i l a b l e l i q ~ i dhead (nozzle subzergence), o r t h e require:: nozzle s i z e , i s reached. T h i s w i l l g i v e t n o;erating p o i n t i n oce of eke t P , r e ~ zones. Zone 1 ( S e l f - V e n t i n a Pioe) A l l nozzle s i z e l i n e s c u t by t h e 1000 G?!: l i q u i d f l o w abscissa i n t h i s zone (IS inches and ~..erge:ce l a r g e r ) w i l l operate as s e l f - v e n t i n g a t t h e corresponding hescs read on the scCa x i s . A t h i g h e r heads t h e y w i l l operate w i t h o u t v o r t e x i n g , p r o v i d i n g t h e f l o w i s l i c f t e d t o 5 1 0 0 0 GPM by t h e downstream p i p i n g conzr31 s y s t g o r equipment. Zone 2 ( T r a n s i t i o n Region1 For a l l heads between 4 and 48 inches, t h e l t C O G?X abscissa l i e s i n tSe T r a n s i r i o n Ke;?on. Vortex breakers would be needed a t these he?cs f o r any in:e-s~cCec! no:r?e s i z e ( 6 t s i S i n c h e s ) . However, i f t h e nozzle i s then o v e r s i z e d to it;€ d e ~ r e et h a t i t would be i n Zone 1 ( e . ~ . , due t o velocity limitations 14 inches o r I z ~ e r ; , t h e l 2 v o r t e x brecker w o ~ l dn o t be netessary. a l t h o u ~ ht h e a v a i l a b l e head w i l l exceed t h a t m q u i r e d and the nozzle u i i l n 3 t operste as s e l f velt'nc.
-
I f the a v a i l a b l e mininun l i q u i d head i s 2 X inches ( t h e i n t ? r s ~ c t i o r .o f the uzzer S ~ ; ~ c ? r y w i l l g i v e ncn-vcr:exin< l i n e and the 1000 GFM c z ~ a c i z yl i n e ) , the f z i l o w i n g a:;rcacf!ts ceceit i o n s w i t h o u t a v o r t e x breaker:
I
Nozzle s i z e s chosen a t t h e intercezz:cn o f l G O O GFU and the a v a i ? a S l e hezcs re:-ired i n Zone 3. such as a - i n c h ( a t 153-inc5 heiid). However, i n p r z c t i c e , t t i s i s u n i i k e l y due t o t h e h i g h f l o w v e l o c i t i e s tkat r e s u l t .
b)
Nozzle s i z e s chosen a t the a v a i l a b l e l i q u i d head ( 2 % inches). b u t t o the r i ~ t ;o f t h e i n t e r s e c t i o n w i t h t h e l O G O GF3 f i o w l i n e . These nozzles nay be i n Zone I c r eve? i n Zone 2. However, i f a nozzle s?z: i s chosen i n Zone 2 , i t would no: reqcit-e a v o r t e x breaker, s i n c e t h e r e q u i r e d f l o w c a p a c i t y (1OGC G?X) i s below t h e c a p a c i t y a t which t h e n o z z l e would vortex.
S e l e c t i o n o f Nozzle S i z e The nozzle s i z e should be s e l e c t e d o f t h e s i z e s i z e as t h e o u t l e t p i p i n g f o r nos: cascs, t h e p i p i n g b e i n g s i z e d f o r v e l o c i t y o r pressure drop. Check f i r s t t h a t t h e nozzle i s l a c e e n o u ~ n t o accept the r e q u i r e d m+ximum f l o w w i t h t h e 3 i n i r n u ~hezd availak:e, u s i n g F i ~ u r e?, t r e - cnezk whether a v o r t e x breaker i s needed. I n t h e exaaz:e give?, a v c r t e x breaker w i l l be r r = ~ + r e idf :
I-II a
II
a)
--- -
,~qenc+is.bet+ieen
4 and IE._?nches a n d n o z z l e ~ T i ei s l e s s than 15 inc?er, ,
If,f o r mechanical r e l s s n s or o t h e r d i s e a vorzEx breaker cancot be accomodatzd, t h e s l r k ~ r c e n c e must be increased (above 48 i n c h e s ) o r a 1 z r r e r nozzle used (12 inches o r biocer:. Notes on S e l f - Y e g t i n o L i n e s I n several s i t u a t i o n s where t h e hesd over a no=z?e i s u n c o n t m l l e d and may bec-,e ve-:, lcu, a " s e l f - v e n t i n g l i n e " should be used, even t h o z j n t h e f l 0 n a l a v a i l a b l e he?d may no: call f c r i t . T y p i c a l s i t u a t i o n s are tower s i d e strezm d r r u o f f s and o u t l e t s t o r e b o i l e r s . UnCe- these condiern, a vov€ex=wil.?never farm. - --+ The drawoff p i p e should be c a r r i e d f u l l noz:!e s i z e f o r a t l e a s t 5 p i p e d i a c e t e r s :el% t:e I t can then be reduced i n s i z e . as d i c t a t t d by n0or;nal p i p e s i z i n g cri:eria. drawoff.
tO!iFIDENTikL
DOt2UE::T
-
1 Not t o be Re~rcduced
STANDARD
D A T A
B O O K
-
PART
1 P A G E 34 O F 6: I Dece-3er.lOir
I11
DRJ5 S ; ? ! N G 8.
I
Vortex E l i m i n a t i o n The f o i m a t i o n o f a w r t e x can be avoided b y one o f t h e f o l l w i n g methods. a method depends on economic c o n s i d e r a t i o n s and process requirements.
of
Design i n Zone 1 ( S e l f - v e n t i n g Pipe) o r i n Zone 3 ( L i q u i d F i l l e d Pipe) and p r u v i d e t h e required head.or l a r g e r . Lou L i q u i d Levea I n s t a l l a baffle a t the q o f the nozzle t o increase t h e su3mergence as s h w n i n t h e a c c o n a n y i n g s k e t c h so i t conforms w i t h t h e r e q u i r e d submergence f o r o p e r a t i o n 5 i n Zone 3 ( L i q u i d F l l l e d Pipe) o f F i g u r e 7. This i s u s e f u l f o r side-connected d r a r o f f s .
(a) (b)
I f due t o process c o n s i d e r a t i o n s t h e draw o f f n o z z l e must be s i z e d t o account f o r operat i o n i n Zone 2. then an e f f e c t i v e v o r t e x breaker must be s u p p l i e d along w i t h the n i n i m u c head r e q u i r e d according t o Zone 2 i n F i g u r e 7.
D e s i m o f Vortex Breakers Two types o f vortex b r e a k e r designs have been found t o be e f f e c t i v e . They a r e t h e f l a t p l a t e In most cases t h e f l a t p l a t e d e s i g n i s s u i t a b l e and rmre and t h e g r i d type ( s u b a y g r a t i n g ) . econonicai. Ciowever, t h e g r i d t y p e i s by f a r t'le m s t e f f e c r i v e vor:ex b r e a k e r and i s r e conmended i n s i t u a t i o n s where i t may be d i f f i c u l t t o f i t a f l a t p l a t e desigm s u m as w i t h l a r g e d i a m t s r nozzles o r when m u l t i p l e draw o f f s c r e emoloyed. Fla:
P l a t e Vortex Breaker
A horizontal c i r c u l a r f l a t p l a t e i s i n s t a l l e d over the The p l a t e nozzle as shown i n t h e a c c o . ~ a n y i n g sketch. dia,ne*&r should be 4 t o 5 t i r e s t h e n o z z l e diameter f o r a s i n g l e draw o f f . F o r m u l t i p l e nozzles. t h e p1a:e should extend beyond t h e s m a l l e s t c i r c l e t h a t completely encloses a l l o f t h e draw o f f s . by t w i c e t h e d i a m t e r of t h e l a r g e s t nozzle. Uhen the C i m e t e r o f t h e draw o f f n o z z l e i s l a r a e r than 15-23: o f t h e vessel d i m e t e r , a f l a t p l a t e v c r t e x breaker design may n o t be p r a c t i c a l and the gr:d t y p e o f vorLex breaker i s then r e c c m n d o d . If a v a i l b l e
Area
= Flow &re3
G r id :';rtex -
Ereaker !S:buav
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-d3e ~i ?laze
Grat;nc;!
The cr:d tv?e of v o r t e x b r e a k e r i s made up of t 5 r e e h s r i z c c t a l l e e o~f j r i d , m:c?ly Sisare, o f t + e type n . m n l y known as subway graLin9 a r w a i k i n g p i a t f o n . it i s m e expensive a flat p l a t e v o r t e x breaker. Eac5 l s y e r c r m s i s t s o f g r a t i n g raCe wi:5 one i n ~ vi e r t i c a l fla: bars a t one i n c h centers. The bars a r e connected by c r c s s - i n m e r s and each l a v e r i s a t r i g n t an?les t o t h e one n e x t to it. As w i t h t h e f i a t p l a t e tyw. these g r i d s s n c v l d extend o v e r t h e nozzle b u t t h e s i d e of t ! e squire needs a be a x n t m of 3 n ~ z z l ed i k x z e r s i n s i z e and i t should be c s s t e r e d over t'.e n o z z l e f o r c s i n c i e draw s f f . For m i x i p i e draw o f f s , t h e s i d e o f t h e scuare srid s h o u l d e x i e n c by one C i a s e r e r (of t h e l a q e s : n o x i e ) past t h e c i r c l e t h a t c c x ? l e r e l y w c i o s e s a l l o f t h e d r a r o f i s . The stercnes C e i w snow -A recs.mended d i r e n s i o n s f o r r o e c i f y i n ~ I b i s type of v c r t s bm'tor. Fo+ a g r i d type v o r t e x breaker t'le n r i n i m l i q u i d l e v e i snouid be no l o - e r thm 3,e +coo l a y e r o f g r j ds
.
typical
l-
HeaAs
The c o m n types o f heads used i n process d r m s a r e Standard Cished heads. d f s h r a d i u s = drum diare:er. Dished heads. knuckle r a d i u s = 0.06 drun diametfi* 2:1 e l l i p a c a l heads. Heni s ~ h e rcia l heaas
. ,
.
Caoacity data f o r 3xe rbove mentioned heads a r e crcsented i n F i g u r e s 2. 3 . 4. and 5.
L -
.
I
I
(c)
C.
l h e se1ec:ion
.
_
_
~NFIDEI:TILLNCURXT
_
-
so:
t o be Reorozuced _-_ . ..
.
.-
I
r+
STANDARD
DATA
BOOK DRUM SIZIriG
LUMMUS
-
P A G E 35 OF
P A R T 111
53
Januzry, 1072
The following recomnendations can be used f o r making a preliminary selection of the hezd type: Standard dished heads a r e only used i n drums a t 1 atmosphere absolute. Hemispherical heads a r e used in drums with a dizmeter larger than 15 f e e t resardless of the design pressure. Dished heads with knuckle radius = 0.06 drum diameter are used when
D < 15 f t , and P < 100 psig where
D = Drum diameter
P
=
Design Pressure
2:l e l l i p t i c a l heads are used when D < 15 f t , and P > 100 psig. The f i n a l s e l e c t i o n of the heads i s made by Project Engineering.
I
The process engineer must have available the various desian paraxeters which e n t e r i n t o the application of the drum design methods. General r e c o m n d a t i b f o r these pzraneters 2r2 given i n this section.
Lfaufd Surge Times
Surge time i s the minimum t i n e required f o r providing rezsonable operetfn: f l e x i b i l i t y . This e personnel t o sense and correct a process u r s e i around time should be s u f f i c i e n t f o r t f ~ operatTn5 a piece of processing equipment such as a pump f a i l u r e . The lag t i r e between sensing 2nd ccrrectin! trouble i s d e ~ e n a e n tuDon the experience o f the personnel o t e r a t i r , ~tbz g n i t z n ~tke dezree cf s c p h i s t i c ~ t i c no f the instrcnentzrion. Recamendations f o r typical liquid suroe t i n e s a r e given in the tzble beic.4. These rec:xencations a r e based on experienced operating personnel and a we;l i n s t r u z e n t ~ du n i t . Z e : 2 5 f ; ~ . 2 r should increase these r e c ~ ~ m e n d esurge d t i r e s by muitipiying the foilcwing f ~ c t 3 r s : Personnel.
Factor
Experienced Fully t r a i n e d Inexperienced
1.0 1.2 1.5
Tc, min
Se rvi ces
I-
Surge drum feeds a given process u n i t , but receives the liquid f r o m another u n i t which is t i e d i n t o a segarate control house
--
Same as above but surge drum receives the liquid f m m a process uni-tt tie8 i**-,m-rtt!& heuse Surge drum t o feed a process u n i t , but receives the l i q u i d f r o m o f f - s i t e tankage Liquid fmm surge drum is t o feed a tower t i e d i n t o a separate control house
.-
-.
%
12
Liquid from surge drum 1s t o feed a tower t i e d i n t o the same-wntrol house a - - ---.
8
Liquid froa surge drum to off-si t e tankage o r d i r e c t l y t o a feed drum f o r another u n i t (gravity f l o r )
3
(continued)
CONFIDENTiAL WCUXEYT
- Not
t o be Re?roducec!
STANDARD
E*
LUMMUS
DATA BOOK DRllM S I Z I N G
-
>
P A R T 111
Services
36 O F 53
January, 1972 TS, min
Same as above but 'liquid i s pumped from t h e surge drum
II
PAGE
S
Liquid from surge drum t o e i t h e r o f f - s i t e tankage o r t o another feed drum. v i a a feed-bottom h e a t exchanger Liquid from surge drum i s t h e s o l e charge t o a f i r e d h e a t e r
10
I
5
I
Liquiii from surge arum feeds a f i r e d r e b o i l e r ; t h e surge time is based on t h e r e b o i l e r vapor expressed a s a l i q u i d (5 minutes) l u s t h e appropriate surge time f o r t h e bottom product based on t e s p e c i f i c s e r v i c e
eh
I I
I I I
Vapor-liquid s e p a r a t o r between a high-pressure and a low-pressure separation unit D i s t i l l a t e drum a c t i n g as r e f l u x accumulators only D i s t i l l a t e drums ( r e f l u x drums) which a l s o s e r v e rs product r e c e i v e r s , the surge time is based on r e f l u x ( 3 minutes) plus t h e appropriate surge time based on t h e s p e c i f i e d s e r v i c e Compressor suction knock-out drums, based on l i q u i d r a t e from l a r g e s t s i n g l e liquid-producing u n i t preceeding t h e conpressor Additional o r ernercpcy surge f o r i n t e r s t a g e knock-out drums (based on maximum i n t e r s t a g e condensate production r a t e )
/&#,pum I I D Rztio f o r Process ~t-4
I
The s e l e c t i o n of a s u i t a b l e veluc! f o r t h e L/D r e t i o o f a process drum i n a p a r t i c u l a r j c b i s effectso' by these f a c t o r s :
I
(1)
P r o c ~ s sc s n s i d e r z t < c n s a r e a primary f z c t o r over c o s t c c ~ s i d e r a t i o n s , meanin9 t h a t i f such 2 choice a r i s e s , t h e shape o f a drum nay be sonewhat f i x e d by requirements r e s u l t i n s from soec-i f i e d l i c u - ~ ~ ' a e ~minirum v;cor i r e s , Z~I_+--~+-:D+ , etc. Very o f t e n t h e r a r i o of L / D i s fixed by p i o z p l t n l i m i t a t i o n s and c l i e n t s a e c i f i c a t i c n s .
( 2 ) Drms w i t h d i z e t e r s l e s s then 2 f e e t nay be e i i f f a r l t t 3 b u i l d and o p e r z t e (mainrsnx.ce
prob1err.s). e s p e c i a l l y i f i n t e r n a i s such a s b a f f l e s , w i r e - n ~ s h pads, s p e c i a l l e v e l cont r o l l e r s , e t c . . a r e t o be used.
(3)
I
The c r i t e r i a
The f i r s t general c r i t e r i o n t o be met i s t h a t t h e L/D r a t i o o f a l l process d r u m should be within the ranoe: 1.5 ,< L/D 5, except i n the c a s e o f s u r g e drtrrrs c p e r a t i n g a t 7 atmosphere absolute, when i t i s cheaper t o use s n a l l e r L/D r a t i o s .
<
12) For operating pressures equivalent t o design pressures between 50 and 603 ? ~ i ,t h e optimum L/D r a t i o i s around 3 t o 4.
I
- =YYf-m? tfm~t d e s i e s i i P e s above 6D0 p s i t h e recornended L/D r a t i o is around 4 to , 5
I
k'here a p p l i c a b l e , as i n Bloomfield Engineering, s i z e s should be a d j u s t e d t o t h e standard ones given i n t h e d r a w i n ~ son Pages 37 and 38. (4)
- -
1
I
Optimum L/D r a t i o s a r e not as m a n i n ~ f u li n t h e czse of dr'ms with co,nplex i n t e r n a l s ss they a r e f o r simpler d r ~ x s .
Cost consideratians d i c t a t o an optimum LJD r z t i o f o r any f i x e d drun voluiite. offered next should l e a d i n most p r s c t i c a l cases t o "nezr nininuinn c c s t desigris. (1)
I
To keep engineering c o s t low, i t i s a d v i s a b l e t o s e l e c t t 3 e a v a i l a b l e standard drum s i z e s f r o m t h e manufacturers. ( I n t h e 51oomiield Division, some s t a n d a r d drum s i z e s have been developed and a r e given i n t h e f i g u r e on Page 37 f o r s u r g e d r u m a t 1 atm. and iir the f i g u r e on Page 38 f o r process drums up t o a nom:nzl 50 p s i maxfmum allowab>k woricing pressure.) . CONFIDENTIAL DOCUI'IEFIT
-
Not t o be Reproduced
I I
FGp CHORD WIDTF!/GIAMETEi?
RATIOS UP TO 0 . 5 D = D r u c D1axe ter = Chorl S e i g h t C = Cnord ieagrh A, = S e , ~ e n t z l or Chord Arcs A = D r m Cross-Sectionzl A r e a
B
H/D F r o n 0.0 To 0.1
H D
C D
A
A s
g
C
&
D
D
A
E
C
A,
D
D
A
-
-
A
E D
C D
& d
I x
--
TABLE 2
DRUM SIZING
H/D From 0.1 To 0.2
cD DA A , .I000 .I005 .I010 1015 1020
..
.6000 .05zO .6013 -0524 .6027 .05?8 .60LO .053i .6053 .a536
-1025 .6@66 .0540 .6079 .O5tL .-1030 1035 6092 OSt7 ..I045 IOLO :6105 :0551 .tll8 -0555
II D
.I290 -1205 .I210 .-12l5 1220
C D
A
.6L?? .0680 .6511 .O68t .6523 .C668 .&Sf(. :06+1 -65L6 .0654
K D
C D -
h
A
.!LO0 .6?&0 .O851 .I405 .6?50 .0@55 .I410 .6?60 -0860 GILIS .bi7I -1420 .b981 .0869
~ -
-c
&
g
g
D
D
A
D
D
A
-1600 -1605 -1610 -1615 .I620
.7?32 .734l .7)51 .7?6C .7369
.I033 -1037 .lOLZ .I047 1051
-1800 .IeGS .I810 .I815 1820
.7684 .7692 .7700 .?/a9 .77:7
.I224 .I229 .l23L .I239 .12U
-9 . . . .,1230 i2if - 6 5 5 ; .C701 . rL?S .l??! .' 6 2 5 .7?7R . I056 .1825 .7:25 .Ilk9 .656"070S .I430 .7001 .0878 .16?0 .7387 .I061 .I830 .I733 .I253 .l2jj .6580 .07m .1&35 .7012 .08i?Z . 1635 .7136 .1066 .I835 -774: -1258 .12LO .65?2 .0713 .I h O .;022 .0666 .I645 .1640 .?LC6 .I073 .IULO .??SO .1261 .12L5 .660f -0717 .ILLS .TO32 .0891 -7415 .I075 .I845 .7758 .I268 .3R7?
&
/
TABLE 2
-
H/D From 0 . 3 To 0 . 4
ItcAs D
From 0 . 4 To 0.5
D
A
-HD
C A , D
A
/I'
PS /'
'
PAGE: 58 o f 63 X Depth = 100
IDATE:
J a n . , 1572
DRW S T 7 T Y G
(h/D)
B=*
V ~ , , l l = 5.876D2, g a l l o n s / f t of s h e l l l e n g t h
LUMMUS
77FIGURE 1
n r1 -
FOR
5-50: L I Q U I D DEPTHS I N C Y C I I I 3 R I C A L SHELLS
DFaoecer of
an.=.
Pee:
..
FIGURE 2 PFPTIAL CAPACITY FOR LIQUID OEPMS I N HEYISPHERICAL HEADS
5-56:
Dlaceccr of D w , F e e t
.
3.-
VFuu
1.964 '>
D,
.
C i i ~(For 2 E c a e )
FIGURE 4
PFRTIAL CAPACITY FOR 5-50': LIQUID DEPTHS It4 DISHED HEADS (Knuckle Radius 0.060)
-
FIGURE 5
PARTIAL CAPACITY FOF! 5-50% L I Q U I D DEPTHS I N STANDARD DISHED HEADS
Diameter of S r r c . Fecc
FIGURE 6
-
