M
A N U F A C T U R E of gas has n o t been m ade obsolete by n a tu ra l gas invasion. N o r has th e need fo r new en g in eerin g developm ent in this field w aned. T h ese facts are clearly evident fro m the P r o duction C onference of A m erican G as A ssociation held M ay 22 and 23 in N ew Y o rk City. T h is, th e first such m eeting a f te r a tw o-year in terv al, p ro v id ed fo u r technical sessions atten d ed by ap p ro x im ately 300 engineers and chem ists of the in d u stry .
N u m ero u s su b jects of pecu liar in te re st an d im portance to gas m en w ere considered. A m ong th em w ere th ree, each rep resen ted by g ro u p s of papers, h av in g b road chem ical en gineering im portance. T h e se related to ( 1 ) the m a n u fa c tu re of w a te r gas o f u n u su al p ro p erties fo r m ix in g w ith n a tu ra l g a s ; ( 2 ) new types o f u n d erfirin g of coke ovens and the reduction of breeze m ade a t ovens ; and (3 ) im proved m ethods fo r rem oval of su lp h u r fro m gas.
W ater Gas for M ixing
N a tu ra l gas has invaded the g re a te r p a rt of the U n ited S tates fo r city supply. I n m an y localities it is m ixed the y e a r ro u n d w ith som e type of m a n u fa c tu re d p ro d u ct b e fo re d istrib u tio n . H o w ev er, in m ost cases it is su p plied w ith o u t m ixing. A n d even in these com m unities th e problem rem ains o f eking out lim ited supplies d u rin g p erio d s of peak dem and o r su b stitu tio n on sh o rt notice in th e event of breakdow n in n a tu ra l-g a s tran sm issio n or supply facilities.
W a te r gas m u st be so used freq u en tly both as a standby fo r em ergency and fo r peak-load ad d itio n s. B u t norm al types o f w a te r gas cannot be occasionally m ixed w ith n atu ra l gas except in lim ited q u an tities w ith o u t changing the b u rn e r p e rfo rm a n c e enough to in te rfe re w ith both household an d in d u strial use. T h e problem of m aking gas th a t can be so added has, th e re fo re , engaged th e a tte n tion of a larg e p a rt of the m a n u fa c tu rin g division of the in d u stry . T h e resu lts o f these effo rts w ere p resen ted in ab o u t ten re p o rts dealing w ith new m ethods of m an u factu re, new processes, o r o th er phases o f the m ix in g problem .
T h e W a te r G as C om m ittee, u n d e r L . J . E ck, chairm an, presented a p ro g ress re p o rt supplem ented by sum m aries o f specific tests in v ario u s localities, in clu d in g th e H u n ts P o in t W o rk s of C onsolidated G as Co., N ew Y o rk City,
th e use of oil-refinery gas a t th e G reen P o in t p la n t of B rooklyn U n io n G as Co., and experiences in su b stitu tio n of m ixed gas d u rin g peak load of the Pacific G as &
E lectric Co.
H ig h e r B .t.u. gas th a n norm al m ade in sta n d a rd w ater- gas sets w as re p o rte d on by engineers o f both Chicago an d P hiladelphia. A strik in g conclusion of the P h ila delphia investigations, as sum m arized by W . K . B eard, w as th e evidence th a t c a rb u re tte d gas of m ore th a n 700 B .t.u. p e r cu .ft. can be m ade a t a slightly low er cost p e r heat u n it fo r solid fuel and oil th a n is attain ab le in sta n d a rd o p eratio n w ith 530 B .t.u. gas. B eard also con
cluded th a t no com plications fro m sm oke, ta r, or o th er difficulties w ere intro d u ced and only m in o r changes in o p eratin g m ethods w ere req u ired . T h e resu lts indicate th a t still h ig h er h eatin g values th a n attem p ted in P h ila delphia are easily obtainable, b u t no evidence w as gaine l as to the u p p er lim it w hich can be safely reached.
C hicago in vestigations indicated sim ilar conclusions w ith definite evidence th a t up to 900 B .t.u. gas can be m a n u fa c tu red a t ap p ro x im ately 160 M c u .ft. p e r m achine- h o u r w ith a sim ple o p eratin g cycle. I t w as discovered th a t the th erm o u tp u t p e r m achine is m aterially g re a te r w ith rich gas th a n w ith th a t o rd in a rily m ade (o f 520 B .t.u .). T h e only com plication re p o rte d w as slightly g re a te r freq u en cy o f rechecking, th e in terv als dependent on the q uality o f oil used.
K . B. N ag ler, describing one phase of the C hicago in
vestigations, drew th e follow ing conclu sio n s: T h e in crease in B .t.u. w as obtained by decreasin g blue gas in th e m ix tu re , th ro u g h low er steam in p u t. T h e solid fuel co nsum ption is u n changed. O il consum ption is increased fro m 3 gal. fo r 530 B .t.u. to 7.5 gal. fo r 8 0 0 + B .t.u. T h e ta r yield is g re a tly increased, fro m 0.2 to 1.1 gal. p e r M . T h e oil efficiency is reduced fro m 100,000 B .t.u. p e r gal.
to 85,000 o r 90,000. T h e increase in th erm capacity p er m ach in e-h o u r ran g es fro m 15 or 20 p e r cen t f o r large m achines to 50 o r even m ore on sm all units.
A s an evidence of th e ch aracteristics o f gas m ade and fuel efficiency obtainable u n d e r com parable conditions, N a g le r p resen ted th e follow ing d a ta in which gas A is th a t norm ally used f o r m ix in g in C hicago; gas B th a t fo rm ally m ade w hen candlepow er of send o u t w as 23 .5 ; and gases C, D , and E , ex p erim en tal p ro d u ctio n m ade in a tte m p t to m atch th e n a tu ra l g a s-w a te r gas m ix tu re now com m only d istrib u ted in Chicago.
310 C h em ica l & M e ta llu rg ic a l E n g in e erin g — V ol.40,N o.6
A special subcom m ittee u n d e r E . L . F ischer, chairm an, investigated ex p erim en tally a t M ason City, Iow a, tw o m ethods of p ro d u cin g rich w a te r gas : ( 1 ) p roduction of a highly c a rb u re tted gas of about 40 p e r cent by volum e of blue gas an d 60 p e r cent oil g a s ; ( 2 ) p roduction of a straig h t oil gas u sing p ro d u c e r gas fro m the g en erato r m erely fo r h eatin g the checker w ork.
T h e com m ittee obtained in the best ru n s on stra ig h t oil gas about 4 h r. op eratio n w ith a m ake of 20 M cu .ft. per hr., fro m 24.5 lb. o f coke, 12.85 gal. of oil, and 24.5 lb.
of steam p e r M . T h e average B .t.u. w as 999, an d the specific g ra v ity of the gas 0.575. T h e cost of m aterials involved w as ap p ro x im ately 62c. p er M . In these ru n s it w as fo u n d necessary to sh u t dow n a t sh o rt intervals, because the offtake pipe o f the g e n e ra to r becam e choked w ith lam pblack, because this pipe w as sm aller in diam eter than desirable fo r th is so rt of operation.
F ro m th e ir heavily c a rb u retted blue-gas ru n s o f about 6 hr. they m ade 22.8 M c u .ft. p e r h r., w ith fuel con
sum ption o f 25.3 lb. of coke, 12.05 gal. of oil. and 27.1 lb. o f steam p e r M . T h e gas m ade w as 1025 B .t.u. p er cu .ft. and of 0.726 sp.gr. T h e cost of m aterials was approxim ately 59.5c. p e r M .
F ro m the tests m ade the com m ittee draw s a series of im p o rtan t conclusions, am ong w hich those of general in terest are :
1. G as can be m ade in a sta n d a rd c a rb u retted w ater-g as set w ith o u t changes of any kind, w hich will serve as a su b stitu te fo r n a tu ra l gas an d will b u rn satisfacto rily in any appliance p ro p erly a d ju ste d fo r n a tu ra l gas w ithout changing the a d ju stm e n t o f th e appliance, eith er w hen m ixed w ith n a tu ra l gas in an y p ro p o rtio n s o r w hen sub
stitu ted 100 p e r cent.
C haracteristics of Gas M ade and F uel Efficiency O btain
able U n d er C om parable C onditions
B .t.u ...
Gal. O i l /M c u .f t...
Lb. F u e l / M e n .f t ..
Lb. S te a m /M cu .ft.
CO.i ...
Iliu m ...
0,...
CO...
H ,...
C H ,...
C iH e ...
N ,...
S p .g r...
2. A sa tisfa c to ry su b stitu te fo r n atu ra l gas m ust con
tain not m ore th a n 35 p e r cent by volum e o f com bined carbon m onoxide an d h y d ro g en an d w ith these p ercen t
ages m u st e ith e r ( a ) have ap p ro x im ately the sam e B .t.u.
value an d specific g rav ity as the n a tu ra l gas, o r ( b ) the heatin g value m ay be less th an th a t of the n a tu ra l gas if the specific g ra v ity is sufficiently low er th an a p p ro x i
m ately the sam e B .t.u. delivery p e r h o u r th ro u g h the b u rn e r orifice resu lts. I f a gas w ith a low er com bined percentage o f h y d ro g en an d carbon m onoxide is p ro duced, th en th e h eatin g value m ay be low ered provided the specific g ra v ity is n o t g re a tly increased.
3. T h e te m p eratu re o f gases leaving the set is the best in d icato r of the q uality o f th e gas being produced.
W h e n m aking stra ig h t oil gas, this te m p e ra tu re variation is the only m eans of co n tro llin g B .t.u. and quality. T h e tem p e ra tu re of the gases leaving the set is th e resu lt of th ree possible variables, v iz .: a te m p e ra tu re o f brick at
A B C D E
540 695 811 826 850
3. 0 4.23 7. 4 8 6.34 8.58
30.0 30.82 32. 12 28.83 31.95
30.0 30.9 0 20.02 25.10 19.80
3. 4 4.3 1.8 2.7 1.6
8.4 12.6 19.7 19. 1 18.9
1.2 0 . 7 0 . 3 0 . 3 0 . 2
30.0 30.2 25.7 2 2.3 21.3
31.7 29.3 29.2 27.6 28.0
12.2 17.8 13.5 19.7 20.7
5. 2 3. 6 4.3
1 3 . 1 5 . r 4 . 6 4.7 5.0
.64 .70 .69 .69
bottom of superheater, rate of oil input, and rate of steam input. F o r a given rate of oil and steam p er m inute definite relations will be found betw een the tem p eratu re of the outlet gas and the tem p eratu re a t the bottom of the superheater. O nce this relation has been established and the desired outlet gas tem p eratu re determ in ed fo r the p articu lar quality of gas desired and fo r th e p artic u la r oil used, v ery constant resu lts can be obtained by o p era
tion on a com bination tem p eratu re tim e cycle as follow s:
( a ) B last of sufficient length th a t the tem p e ra tu re a t the bottom o f the su p erh eater reaches th e desired m axim um .
(b ) A ru n of definite tim e period w ith definite rate of oil and steam allow ing tim e fo r a steam p urge a fte r sh u ttin g off the oil.
Carburetted B lu e Gas
4. In m aking carb u retted blue gas it is advisable to follow the sam e procedure as to cycle and tem p eratu res as fo r stra ig h t oil gas although a co n stan t B .t.u. of gas can be m ade by vary in g the blue gas-oil gas ratio.
C onstant B .t.u. value, how ever, is not in itself sufficient as the constituents of the gas are also im p o rtan t. T h e best operation as to constancy of gas is obtained by constant gas outlet tem p eratu re and it is recom m ended th a t the tem perature-tim e cycle be follow ed fo r this m ethod also. I t is necessary to d eterm ine the pro p er tem p eratu re of the outlet gas fo r each m achine and each g rad e o f oil. T h is te m p eratu re should be the highest tem p eratu re that can be used w ith o u t lam pblack p ro d u c tio n ; in o ther w ords, the m axim um cracking obtainable for the p articu lar oil used w ith o u t hydrogen production. T h is should give m ax im u m oil efficiency, m axim um m ethane p roduction and m inim um production of illum inants possible w ithout hydrogen production.
5. P ro p e r operation will require tw o pyrom eters, one located a t the bottom of the su p erh eater an d one in the connection betw een outlet o f su p erh eater and w ashbox.
F o r best results a tw o-pen reco rd in g p y ro m eter show ing the tem p eratu re at both points is recom m ended.
6. F o r blue gas-oil gas m ix no changes of any kind are req u ired to the set unless fo r a p a rtic u la r p lan t it is fo u n d th a t the oil spray and pum ps are too sm all to supply th e required ra te of oil flow.
7. F o r the production of stra ig h t oil gas it will be necessary to provide m eans of keeping the offtake pipe an d w ashbox clear of lam pblack if continuous o p era
tion is to be m aintained as d u rin g the tests th ere w as an accum ulation o f lam pblack sufficient to force sh u t
dow n a fte r about five h o u rs ru n . T h e effect on this condition w hen using gas oil w as not determ ined.
8. S tra ig h t oil gas can be su b stitu ted successfully w ith low er B .t.u. values th an blue gas-oil gas m ix be
cause of the low er specific g rav ity and low er percentage o f illum inants.
9. R esults o f te sts indicate th a t the reduction in B.t.u.
value due to com pression an d cooling is ab o u t the sam e fo r the tw o gases.
10. T h e capacity of the set w hen m aking stra ig h t oil g as (assu m in g provisions fo r disposal of lam pblack as m entioned above are m ad e) is ap p ro x im ately 9 p er cent less (o n a volum e b asis) th a n the capacity of th e set w hen using coal and producing 600 B .t.u. carb u retted blue gas.
11. T h e capacity o f the set w hen m aking blue gas-oil
June, 1933 — C h em ica l & M eta llu rg ica l E n gin eerin g 311
gas m ix of ap p ro x im ately 1,050 B .t.u. is ap p ro x im ately th a t th is p u rg in g can be accom plished w ith w a te r sprays.
p e r cent g re a te r th an the set capacity w hen p ro d u cin g H ig h -p re ssu re a ir is a m ore sa tisfa c to ry ta r atom izing 600 B .t.u. c a rb u re tted blue gas. m edium th a n steam , an d w ith w a te r fo r p u rg in g and B o th o f th e above are based on u sing fuel oil fo r th e w hen m o to r d riv en blow ers and e x h a u ste rs a re used, high B .t.u. gas and gas oil fo r the 600 B .t.u. gas. steam g en e ra tin g equipm ent is n o t essential.
12. I t is believed th a t h ig h er capacities m ay be real- O p e ra te d w ith o u t a fuel bed, w ith o u t steam o th er than ized w ith eith er m eth o d of op eratio n w hen u sing gas oil th a t g en erated w ith in the m achine, w ith o u t e ith e r lam p-instead of fuel oil. black o r ta r as b y p ro d u cts, th e recirculated oil-gas process offers d istin ct possibilities as an econom ical R e c irc u la te d O il G as m ethod fo r co n v ertin g abandoned carb u re tted w ater-g as
sets into stan d -b y equipm ent fo r m eetin g peak loads and In v estig atio n s u n d e r E . S. P e tty jo h n , research engi- failu res o f supply in n a tu ra l gas territo rie s,
n eer a t th e U n iv e rsity o f M ichigan, have resu lted in T h e essentials fo r successful o p eratio n in ad d itio n to th e developm ent of a new oil-gas process w hich has c a re fu lly con tro lled recircu latio n a r e : ( 1 ) A ta r b u rn e r been christened “ the recircu lated oil-gas p rocess.” T h e w hich will give com plete com bustion an d w hich will not object of th is m ethod is to m ake th e h ig h est possible seep d u rin g th e m ake p e rio d ; ( 2 ) T h e m ain ten an ce of h eatin g value by oil cracking in a sta n d a rd w ater-g as te m p e ra tu res in the su p e rh e a te r w ithin th e ran g e o f plus m achine, w ith o u t conversion of any p a rt of th e oil into o r m inus 25 deg. above o r below 1475 deg. F .
hydrogen and lam pblack. E lim in atio n o f th is com plete T h e resu lts obtained in this initial te st a re distinctly crack in g does tw o th in g s of a d v a n ta g e : ( 1 ) I t p rev en ts favorable and indicate th a t th e recircu lated oil-gas lam pblack tro u b les w hich are serious in w a te r gas equip- process does p ro v id e a suitable m ethod fo r th e utiliza-m e n t; (2 ) it p rev en ts ad d itio n o f h y d ro g en to the gas, tion of abandoned c a rb u retted w a te r-g a s eq uiputiliza-m ent in w ith a consequent low ering o f both h eatin g value p e r the p ro d u ctio n of a h ig h -h eatin g -v alu e oil-gas as a sub-cubic foot an d specific g rav ity , both of w hich changes stitu te fo r n a tu ra l gas d u rin g peak loads and d u rin g a re u ndesirable w hen th e p ro d u ct is to be m ixed w ith failu res of supply.
n a tu ra l gas. O p e ra tin g resu lts obtained in these in vestigations
P e tty jo h n describes his process as fo llo w s : w ere satisfacto ry . R eq u irem en ts w ere ap p ro x im ately T h e recirculated oil-gas process w as d esigned to pro - 10.8 gal. o f oil and 2.7 gal. of b u rn e r tar, w ith 10.6 lb.
vide both th e necessary co n tro l of tim e of contact and o f steam p er M . T h e m ake in a 10-ft. sta n d a rd w ater-o f tem p e ra tu re tater-o prater-oduce a gas ater-of high m ethane cater-on- gas m achine w as a p p rater-o x im ately 86 M cu .ft. p e r h ater-o u r te n t w ith o u t th e fo rm atio n of lam pblack. T h e oil to be of gas. hav in g th e follow ing analysis an d ch aracteristics,
cracked is atom ized into th e top of the c a rb u re to r ,
- . , , 1 , w ith b a ck -ru n t a r W ith o u t b a ck -ru n t a r
th ro u g h a sta n d a rd type oil spray, ll i e atom ized p a r- co*... 2.6 3.4 tid e s a re vaporized an d partially cracked as they a re gj'wunant»... 24.2 30.0 carried rap id ly fo rw a rd by steam su p erh eated in th e go ... 2-8 ^2.0 checkerbricks w hich have been su b stitu ted fo r the fuel c h,'. '. '. '. . 33!8 36! 8 bed in th e g e n e ra to r to increase th e available h eat sto rag e obVerVed heat V a l u e . ' . 1.030 i.loo capacity. A s this m ix tu re reaches th e base o f the car- Observed specific gravity... 0.726 0.7 3 8
b u re to r p a rt of it is w ith d ra w n th ro u g h an a u x ilia ry line T h e o u tstan d in g conclusions fro m the investigation an d recirculated th ro u g h th e g e n e ra to r and c a rb u re to r are expressed by the a u th o r as follow s:
in creasing the velocity o f the atom ized oil p articles F ro m these resu lts it m ay be seen th a t the recirculated th ro u g h these h ig h -tem p eratu re zones. T h e re m a in d e r oilgas process m ay be used to produce a hig h h eatin g -o f the p a rtia lly cracked -oil v a p -o r passes u p w a rd th r-o u g h value gas w hich m ay be m ixed w ith an d su b stitu ted fo r the su p e rh e a te r a t a ra te w hich allow s a longer tim e o f n a tu ra l gas in appreciable q u an tities fo r sh o rt periods of contact in th is low er te m p eratu re zone. B y v a ry in g bo th tim e. T h e u p p er lim it w as n o t d eterm in ed , b u t it is the p o rtio n of th e oil ru n d u rin g w hich the p a rtia lly believable th a t com plete su b stitu tio n is possible,
cracked oil gas is recirculated, an d th e q u a n tity recircu - E le v e n -h u n d re d B .t.u. gas w as m ade w ith less than lated th ro u g h changing th e volum e o f steam ad m itted 11 gal. o f oil p e r M . c u .ft. I t is believed th a t th is to th e asp ira to r, th e qu ality of th e finished gas m ay be q u a n tity can be reduced w ith additional o p eratin g e x
controlled. perience provided 'the b y p ro d u ct ta r is used fo r u n d
er-T h e ta r th a t is fo rm ed is sep arated fro m th e gas firing the m achine,
stream in th e usual m a n n e r and is re tu rn e d to th e gen- A ll o f th e ta r produced by the process m ay be re-e ra to r th ro u g h a bustlre-e pipre-e and b u rn re-e rs to providre-e th re-e tu rn e d to the g e n e ra to r as e ith e r h e a tin g -u p ta r, b u rn e r heat fo r oil cracking. A n y excess above the q u an tity ta r, o r b ack -ru n ta r. T h e re a re no o th e r b y p ro d u cts o r necessary fo r w a rm in g -u p the m achine an d fo r com bus- w aste pro d u cts. T h e process w as operated w ith less tion d u rin g th e blast m ay be re tu rn e d to the g e n e ra to r th a n 11 lb. of steam p e r M . c u .ft. o f gas m ade. I t is th ro u g h a sp ray in the c h arg in g cover. In th is m an n er, believed th a t th is q u a n tity can be reduced, if n o t elim i-the single b y p ro d u ct o f th e process is elim inated. nated, by g e n e ra tin g the process steam w ith in the m a
i n w a te r-g a s p lan ts w hich have been p artially abati- chine,
doned, th e g en eratio n o f steam m ay be ex trem ely costly T h e m odifications to th e sta n d a rd three-shell w
doned, th e g en eratio n o f steam m ay be ex trem ely costly T h e m odifications to th e sta n d a rd three-shell w