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Gas Proce!Sing Developments
Claus plants prove flexibleKey design features can make for
easeof operation under diverse conditions
H. Fischer, Lur g i GmbH , Frankfurt a m M a in ,W. G e rman
y
LAUS S 1L f R R EC VE RY plant s p ro id e fl xibi lit y tomee t
m os t re quir m ent s w he r h yd rog n sulfiq e. mu st beco nve
rt ed t o !e m nt a r y s ulfur . Part -loa d ca n b r edu ced
toless th a n 5 % whil e a dd itional gase s co nt a inin g o th er
sulfuro mp oun d s ( i .e., so ur wa ter s tripp r gas) a n b e pr
oce sed
wi th ou t fu rt h r tr ea tm ent up to a ra tio of 2 : 1. l-1
2S to S 0 2 inth e ta ilgas . l l ydr oc a rb o ns, a mm o nia a nd
cya n id ca n a lsob fed in hi gh o ne nt r a tio ns w ith o ut im
p a irin g s ulfur qu a lity. Su ch feeds a re li mi ted o nl y b y
nece ssa r y a ir sur p lu s s in ere sidu a l o xy ge n a nd su
lfur di oxid fo rm ed in th e a ddi tio na lgas is co mp ns a te d
b y h ydro g n sulfid in th e m a in gasstr a m . H yd rog n sulfid
e co nt ent s in fee d gas to th e sulfurrecov r y un it ca n va r
y t hni a lly fro m a lm os t 100 vo l % toa rou nd 5 vo l %. Us of
oxyg n in ad d iti o n t a ir is o f g rea tadva n tag in tega rd
to pr odu ct impr ov mc nt , cap acity increa se, o r in v s tm e
nt redu ct io n , no t o nl y in r a ng es bel ow 20vo l % wh e n
on e o xyg e n must be used , 1 bu t a lso in ra ngesa bo ve 20 vol
% .
Th e ke y to m as t.e rin g th se m eth od s o f handlin g s
ulfur ousg.a s lie in bu rn e r equipm nt a nd c mb u stio n cha mb
r destgn .
FLEXIBLE CAPACITYAn 80 tp d C la us p lant with a Su lfreen
tailga s unit i s ru n -
Fig . 1 -C ia us -Su lfreen plant design .
nin g tro ubl e -fro in tit load ra n ge o f I OO .'f" to less
th a n : %.S ulfu r y i ld (Ta ble 1) 111 ex cess of 93.0 % a rc o
bt a tll d
fro m a feeds toc k o f 90 % or m ore l-1 2S , I % or le s h ydr
o ca rbo n s.
Load range~ 50 %
30 .0 -36%20.0-25%
9 .5 - 1 0 %4 .8 - 5 .5%
TABLE 1Sulfur yield , %
99 .25 - 99 .399 .3-99 .699 .5 - 99 .695 .4-95 .593 .0 - 95
.0
At loa d r a n ges bel ow 20 %, th e pl a nt (Fi g . 1) o p r a
teswithout th e Su lfre n ta ilgas plant. S o ur gas fr m a D EA r
ege nerat o r is pa sed throu gh a se parat or to th combusti o
ncha mb e r burn e r. This speci a l burn e r (Fig . 2) co nt a in
s anumb e r o f sin gle burn ers a rr a n ged in a c ir cle a round
a ce ntr a l burn e r muffl e . H e re , so ur gas rca ts with a
ppropri a tequanti ties o f a ir. A t m inimum o pe r a tio n (be
low 20 % load )so u r gas i s rout ed thr o ugh a se pa rat ed ontr
ol sys tem a ndburner ti ps a re in serted in som e of th s in gle
bu r ne rs . An
a ppropr ia te qu a nt ityof
r 'Cycle g a s is withdr awn upstr eam o fth e ta ilgas pr o
cess thr ough su lfur co nd en se r and s e parat o rusing th
blower a nd pr eh ea ted in th rec ycle ga s h a te r orregen e ra
tio n ga s hea te r. It is th ' n fed t o th in gle burn e rsthrou
gh th e ou r gas lin e to kee p th e in gle burn e r cool eda nd
free o f su lfur , to permit a suffi ci nt tr a m o f pr o cess
gasto be unif o rml y a ppli ed to th e down s tr ea m p lant sec t
io n s,an d to m a intain th e o pera t ion tt: mp er a tu te . A
suffi ie nt fir e-
Hydrocarbon Processing, April 1985 79
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Re c yc lo gas
An
P ilo t b urner Com bu s tto n chambe r
Co rn bu ' II n ch rnb r Reac tion cham ber
Fig . 2 -Spec ta l Claus burner design .
box tcmp e ra tu rc is m ai n tai ned a nd p la nt hea t l o ~ s
e sa rcorn p n sa te cl fell b y burnin , a pp r o priat e quantiti
es of fu e l
ga s wh e n th e load fa lls below 20% of ca pacity. Fuel gas
combustion mu s t d finitely be free of soot to e nsure producti o
n
o f quality br i g ht yellow sulfu r. The quantity of air add
edmu s t be r_eg u lated to maintain an H 2S / S 0 2 ratio at 2/1
upstream of th e th e rm a l incin e ra tion . This air
requirementdr o p r ea tl y a th ' so ur gas feed d ec re a es ,
ther efore, atloa ds o f I . s th a n 10 % , fu el g a s e ~must be
burned soot free a tI ss th a n 70 f< of s to i b io metri c at
5% loa d .
ui t a ble bum er s a rra nge d in tll
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Pdo l burner Co mbu s11on c homb r
Combust1o n chamber Reac tiOn c h ambe r
Fig . 4 - C i aus burne r adapted for oxygen sup p ly.
F i ' 3. R i h Adip s lution fr m th e co t absorber 1s rt'~ rn
e r at e d toget h e r with t h e re m a ining Adip so luti on
.
H yd roc a rb o n co nt nt d epends upon o ri g in an d ty pe
ofwa tc wa te r (lea te d . O n e C la u s- ulfr ec n p la nt hand
les as 1u r wa t r s t r ipp e r ga s w hi c h va r i s thmugh th e
r a n ge ss h o wn in Ta b le 3.
TAB LE 33.6-12 .2 vol %
13 .2 - 23 .2 v o l %17 .2 - 4 .5 vol %66 .0 - 60 .1 vol %
Furth rm o r , a ll hvdro arb n s from 0 ::1r r pr ese nt d in
th e ga s . I ~ ad diti o n , th b u s ga s which is sa tura t d
with s tea m a t 40 a nd a pr e ur e of 1.5 bar ab s lu te ,flu c
tu a t a lso. T h s < . ~ r ea lso th r oug h th e rang e h ow n
in' ! ab le 4.
TAB LE 498.3 - 97.4 vol %
1. 3 - 1 .6 v o l %0 .4 - 1 .0 vol %
In s pite ft h se flu c tu a t ions th s ulfur yie ld from th
plam(s imilar to Fi g. I ) op e ra ti n g a t full loa d is 9i.l to
9i.S% forth e C la u s un it a nd 99. 1 to 9.5 % fo 1 th e ' lau a
n d Su lfr ee nun its L g th cr.
Pr tlu t is o f a good br i r )JI ye ll ow co lo r. It co n ta
in s th eimpuriti s sho wn i n Tab le 5.
AshFeSi 0 2MSBitumenMoisture
TABLE 51- 3 pp m
0 .6 - 1.67 ppm0 .22-0 .72 ppm
10 - 12 ppm2- 4 ppm
87 - 124 ppm
An th r p lan t is de s ig n e d fo r a b us ga s a nd a so u r
wa te r' l l ipplT ga a s s h ow n in T i1hk 6.The p lan r is s m a
ll with tw o reactor stages a nd a th erllla l inc inera to r. C a
e o n1 e fn rn Arni sn l " " 'h dc s ulfurization o l al l la l ga
. ifi a tio n s tr ea m .
: \ 'mura l gas is a\a i labk a ~ fue l ga fo r ~ t a n i n gup
th e( : ! a u ~pl a nt . Th t.: p lan t is u n u ~ u al in that it
i d e i ~ ne d to be
hu down
