936
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y V o l. 5, No. 11 th ro u g h fo u r iron flues of five inch es d iam eter. T h eseflues ex te n d len gth w ise w ith in th e re to rt as show n in
a t i g h t fit. T h e d o o r is s h u t tig h t ly b y m e a n s of four c a s t iro n e c c e n tric c la m p s w h ich a c t o n tw o ste el bars --- --- e x te n d in g a c ro ss th e outer
1. R a ilw a y sw itch.
2. C h arco al yard . 3. P la tfo rm scales.
4. C o rd m easure.
5. W ood y a rd . 6. R e to rt b u g g y tra c k . 7. R e t o r t buggies.
8 . C h arco al ch u te.
9. W ood c h u te.
10. R e to rt bu g g y p latfo rm . 11. R e to rt d oor p latfo rm . 12. R e to rt ru n n in g bo ard . 13. S teps.
14. G as sto ra g e ta n k . 15. F irin g p latfo rm . 16. G as p ip e to fu rn ace.
17. G as p ip e to ta n k .
Pl a t e 1 18. F u rn ac e .
19. F lu e by-pass.
20. S tack . 21. R e to rt.
22. H e a t in su latio n . 23. R e to rt door.
24. D oor clam ps.
25. B o tto m v a p o r o u tle t.
26. T a r sep a ra to r.
27. S e p a ra to r t a r ta n k . 28. P ip e to condenser.
29. C ondenser.
30. P y ro lig n eo u s acid ta n k . 31. G as bo o ster.
32. E lec tric m otor.
33. G as v e n t to air.
P la te s 2 an d 3, te rm in a tin g in retu rn bend s a t th e b a c k en d of th e re to rt. F ro m th e n ce th e y ex te n d to th e fro n t end of th e re to rt w here th e y en ter a sm oke ch am b er, w h ich in tu rn opens in to th e sta c k . T h e course of th e h ea te d gases of co m bu stio n is show n b y th e arrow s in P la te 2.
T h e w ood for d istillatio n is p iled v e rtic a lly in th ree re to rt b u gg ie s w ith sides m ade of steel screening. T h e b u gg ies op erate on steel rails w hich co n tain a re m o v ab le
su rface of th e door.
T h e o u tle t fo r th e prod
u cts of d istillatio n is at the b o tto m of th e reto rt, Plate 4, w hich is sloped so that th e o p en in g co n stitu te s the lo w e st p o rtio n o f th e inner su rface of th e reto rt. The liq u id a n d gaseous products are th u s co n d u cte d from the r e to r t th ro u g h th e outlet in to th e ta r sep arato r, which is air-cooled . T h e por
tio n s n ot condensin g con
tin u e to th e to p of th e sepa
rato r in to th e water-cooled condenser, P la te 5. T h e dis
tilla te s are co llected in a sto ra g e ta n k and the com
b u stib le gases are stored in a gas holder.
T h e n o tice a b le features in th e design o f th e retort a b o v e d escrib ed are: (1) the m eth o d o f in tern a l heating b y m eans of flues located e n tire ly w ith in th e main sh ell; an d (2) th e drawing off of v a p o rs fro m th e bottom of th e re to rt.
T h e a d v a n ta g e s of in
te rn a l firin g o v e r th e custom
a ry m eth od of extern al heat
ing are consid ered to consist la rg e ly in eco n o m y of fuel a n d co n tro l of te m p e ra tu re . B y th o ro u g h insulation of th e re to rt shell, rad ia tio n losses fro m th e shell are m in im ized , th e te m p e ra tu re o f th e s ta c k gases is more n e a rly th a t of th e r e to r t in terio r, th e uniform distri
b u tio n of h e a t p re v e n ts lo cal o v e rh e a tin g , and the re
to r t suffers less d ep re cia tio n due to un equal strains fro m high te m p e ra tu re s th a n in th e case of retorts exp osed to th e d ire ct scalin g and b u ck lin g action of heat.
A n u m b er of co n sid e ra tio n s d ete rm in ed th e selection
34. B ack-fire tra p s.
35. G as t a r ta n k . 36. R efining still.
37. C ondenser.
38. D istilla te feed ta n k . 39. P u m p .
40. Oil se p a ra to r.
41. Oil receiver.
42. C ru d e alcohol ta n k . 43. W o rk tab le.
44. T ra n s fo rm e r a n d sw itch . 45. Sew age basin.
46. S till t a r ta n k . 47. T a r ta n k s.
48. C ru d e w ood v in e g a r ta n k s . 49. B uilding.
sectio n a t th e re to rt door, th u s fo rm in g a co n tin u o u s r a ilw a y fro m th e fore end o f th e re to rt to th e w ood y a r d and ch arco al pile.
T h e re to rt door and door sea t are m ade of ca st steel and are c a re fu lly p la n e d an d m illed so as to insure
of a b o tto m v a p o r o u tle t. I n th e d is tilla tio n of the co n ife ro u s w oods i t h a s b e e n th e w rite r s ’ exp erien ce t h a t co k e d e p o s its u s u a lly e x is t on c h a rco al d ra u n fro m th e b o tto m of th e r e to r ts . I t is g en e ra lly assum e t h a t su c h co k e is th e p r o d u c t of s e c o n d a ry distillation
Nov., 1913 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 937
Pl a t e 3
m ixture w ith th e lig h te r- an d low er-bo ilin g p rod u cts resulting from th e d eco m p o sitio n of w ood. A slight cooling of th e v a p o r cau ses a
change in th e co n ce n tratio n of th e vap o r’s co n s titu e n ts and ta r is precipitated in m in u te p a rticle s which are carrie d a lo n g m ech an i
cally. T h is, h o w e ver, cau ses an increase in th e d e n sity of th e vapor and it te n d s to fa ll b a c k into th e re to rt. W h en it does this it b ecom es reh ea te d , b u t in
stead of a ctin g as it did a t th e time of its fo rm atio n , it is n ow fraction ally d istilled , g i v i n g off variou s lig h t oils and fin a lly being d ecom posed w ith co k e as the residue.
T he b o tto m o u tle t sh ould elim inate th is p o s s ib ility th ro u g h active co n v e ctio n cu rren ts and distribution of h e a t w ith in th e retort. T h u s th e v a p o rs rise on either side of th e re to rt in th e flue area b etw e en th e o u ter side of the b u g g y and re to rt. T h e vapors th ere p ass alo ng th e to p , approaching fro m b o th sides a region near th e to p cen ter, pass through th e w ood (w h ich is p iled vertically) in th e b u ggies, an,d thence along th e b o tto m o f th e buggy and r e to rt to th e v a p o r outlet, w hich is u n der a slig h tly diminished pressure due to th e suction prod u ced b y th e co n d e n se r
or the fan. S h o u ld th e ta r for th e reasons a b o v e given become liquefied, it flow s b y g r a v it y in to th e va p o r o u t
let and is n o t su b je c t to red istillatio n . T h is
ex-W ith th e fu rth e r assu m p tio n th a t th e tim e of d is
tilla tio n requ ired 20 hours of firing, th e to ta l co n su m p tio n of h ea t u n its w as co m p u ted as sho w n on follow ing page.
S+ond
Pl a t e 4— Fr o n t Vi e w. Re t o r ta n d Ap p a r a t u s Se t Up
T o su p p ly th is h eat, use w as m ade o f th e fo llo w in g co m p u tatio n :
Q = A ( T — t) (r + c) w here Q den otes h e a t sup-p la n a tio n has been verified b y a ctu a l osup-p eratio n , coke b ein g fou n d on th e ch arco al o n ly w here oleo- resin or “ p itc h ” had p re v io u sly existed in th e w ood.
F o r th e purpose of d ete rm in in g th e size of flues th e th e fo llo w in g a ssu m p tio n s w ere m ade:
of ta r. In oth er w ords, w hen ta r is in th e process of form ation from w ood, it form s a high b o ilin g vo la tile
(1) T h e d istilla te has th e sam e av erag e p ro p e rties as w ater.
(2) M ax im u m d istilla te p e r cord, 300 gallons.
(3) R a d ia tio n of in su latio n , 4.56 B. t. u. p e r sq. ft. p e r m in u te.
(4) R ad iatio n of exposed door, 24.54 B. t. u. p e r sq. ft. p er m in u te.
(5) A tm ospheric te m p e ra tu re , 70° F.
(6) M ax im u m te m p e ra tu re inside re to rt, 700° F.
(7) T e m p e ra tu re of h e atin g gases a t e n tra n c e to flues, 1500° F.
(8) A verage te m p e ra tu re of h e atin g gases upon leaving flues, 700° F.
(9) Specific h e a t of r e to r t steel a n d iron of buggies, 0.12.
(10) Specific h e a t of wood, 0.650.
(11) M ax im u m non-co n d cn sab le gas p e r cord of wood, 10,000 cu. ft.
w eighing 0.08 p o u n d p e r cu. ft.
(12) Specific h e a t of non-co n d en sab le gas, 0.237.
(13) C hem ical reactio n s of a n e n d o th e rm ic c h a ra c te r balan ce th o se of an exotherm ic c h arac te r.
(14) A verage ra d ia tio n of flues, 3.63 B. t. u. p er h o u r p er sq. foot per degree F .
(15) A verage co n v ectio n from flues, 1.06 B. t. u. p er h o u r p e r sq. ft.
•per degree F .
938 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y V o l. 5, No. u
Pl a t e 5— Si d e Vi e w. Re t o r t a n d Ap p a r a t u s Se t Up
To t a l Co n s u m p t i o no f He a t Un i t s
B. t. u.
(1) T o h e a t a n d v ap o rize 150 gallons of d is tilla te ... 1 ,4 3 0 ,0 0 0 (2) R ad iatio n th ro u g h in s u la tio n ... 1 ,5 1 2 ,0 0 0 (3) R a d ia tio n th ro u g h exposed d o o r... 41 2 ,0 0 0 (4) T o h e a t buggies a n d r e to r t 600° F ... 9 9 0 .0 0 0 (5) T o h e a t wood 300° F ... 300 ,0 0 0 (6 ) H e a t c arried aw ay by non-condensable g a se s... 5 6 ,7 0 0 (7) M in o r lo sses... 100,000
op eratio n of th e re to rt, w h ich requ ires from 18 to 20 h ou rs per run o f th ree -e igh th s to on e-h alf cord of wood.
In P la te 6 is g iv e n a general v ie w of th e p lan t as it ap p eared sh o rtly a fte r its in stalla tio n .
La b o r a t o r y o p In d u s t r i a l Ch e m i s t r y Un i v e r s i t y o f Wa s h i n g t o n
Se a t t l e
A N A P P A R A T U S F O R D E T E R M I N I N G T H E M E L T IN G P O I N T S O F S U B S T A N C E S O F I N D E F I N I T E
M E L T I N G P O IN T B y A . P . Bj e r r e g a a r d
R eceived Ju ly 30, 1913
T h e d ete rm in atio n o f th e tru e m eltin g point of su b stan ces w hich do n o t m elt sh a rp ly a t -a definite te m p e ratu re b u t w h ich g ra d u a lly soften under the influence of h e a t and fin a lly b ecom e so ft enough to be liq u id , is one of g re a t d ifficu lty . In d e e d it can hardly be said th a t such su b sta n ces h a v e a n y tru e melting p o in t. O rd in a ry coal ta r pitch such as is used for roofing, e tc., is an exam p le of th e class of substances under discussion here. A s is w ell k n o w n th is material a t th e o rd in a ry atm o sp h eric te m p e ra tu re when struck w ith a h am m er flies to p ieces lik e glass. Nevertheless, if a b arrel of it sta n d s for a n y len gth of tim e the pitch w ill slo w ly flow o u t of e v e r y c ra ck and crevice or out of th e open b u ng-h ole ju s t lik e a liq u id . I t m ay indeed be called a b rittle liq u id , an d th is class of substances m igh t be called solid liqu id s. I f coal ta r pitch is w arm ed a little it g e ts so fter an d flow s somewhat m ore ra p id ly ; if it is fu rth e r h e a te d it becom es still so fter an d flow s still m ore ra p id ly . F in a lly , when h o t enough it can be m ade to flow n ea rly or quite in s ta n ta n e o u sly like w ater. W h en shall we say that co al ta r p itch is m elted?
P e tro le u m a sp h a ltu m s prep ared b y oxidizing petro
leu m resid u u m also b elo n g to th is class of bodies, a lth o u g h th e ir ch a ra cte ristics are so m e w h at different fro m th o se of coal ta r p itch in th a t th e y are softer at o rd in a ry te m p e ratu re s an d requ ire higher tem pera
tu res to flow to g e th e r wrhen exp osed fo r long periods of tim e to sm all degrees o f h e a t. T h e y also have a
T o ta l h e a t lo st in 20 h o u rs ... 4 ,8 0 0 ,7 0 0 T o ta l h e a t lo st per h o u r (ro u g h ly )... 250 ,0 0 0
p lied ; A , th e to ta l area of th e flue su rfaces; T , th e a ve ra g e te m p e ratu re o f th e gases w ith in th e flues;
t, th e a ve ra ge te m p e ratu re w ith in th e r e to rt; r, h ea t un its given off b y rad ia tio n ; and c, h ea t u n its g iv e n off b y co n v e ctio n . H ence,
Q = 0.416 X 3.14 X 16.6 X 8 (1500 + 700/2 — 700) (3.63 + 1.06),
or 325,000 B . t. u. will be sup plied per hour. A
c-Pl a t e 6
c o rd in g ly b y co m p u tatio n , th e h e a t exch an ge is show n to be m ore th a n sufficien t to p rod u ce d istillatio n ta k in g p lace u n der th e co n d itio n s as a b o v e assu m ed , and this c o m p u ta tio n is verified b y th e resu lts o b ta in e d in th e
Nov., 1913 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y higher ran ge of m eltin g p o in ts as th is term is u n der
stood in th is article.
E xp e rim e n t sh o w s th a t an air-b lo w n p etroleu m a sph altu m w hich w hen h e a te d rath er ra p id ly becom es liquid a t a b o u t 1 3 5 0 C ., w ill flow dow n an inclined plane upon w hich it m a y be placed a t 40 0 C . if k e p t a t th a t te m p e ratu re a lon g tim e, sa y 18 hours. Shall we sa y th a t this su b sta n ce fuses a t 40 0 C . or a t 135 0 C.?
T h ere ap p ear to be tw o sta ge s or tw o te m p eratu re points in th is grad u al so ften in g, w hich m ay be of im portance in th e ex a m in a tio n of these substances.
First, th ere is th a t te m p e ra tu re p o in t or ap proxim ate point, a t w h ich th e firm solid or pseudo-solid m aterial ju st b egin s to soften , so as to be slig h tly p lastic, or so th a t if le ft a lon g tim e a t th a t te m p eratu re it w ill flow and fin a lly com e to a le v e l in its contain er. Sec
ond, th e re is a te m p e ra tu re a t w hich th e su b stance is so fluid th a t it can re a d ily and q u ic k ly flow to a level in its co n tain in g vessel; in o th er w ords, it possesses the prop erties u su a lly ascrib e d to liquids.
T h e a p p a ra tu s now to be described is one for de
term ining th e te m p e ra tu re of th is second kind of m elting. I t can sca rce ly be called a flow po int a p paratus, alth o u g h th e flow of th e sam ple is m easured.
It consists o f a b lo ck of iron of su itab le dim ensions, with one fa ce a t an an gle o f 4 5 ° to th e horizontal.
This in clin ed fa ce is p ro v id e d w ith groo ves, as fu rth er described below . T h e b lo ck is also p ro vid e d w ith a sm all cistern to co n tain m ercu ry in w hich is placed the th erm o m eter for rea d in g th e tem p eratu re of th e block. A u sefu l size for th is a p p a ra tu s is abou t 4V2 inches w id e, 4 inches high and a b o u t 5 inches long.. T h is w ill co n tain 9 gro o ves of th e size de
scribed below . A to p v ie w is show n in F ig. x, and a side vie w in F ig. 2; here, A is th e m ercu ry
1 lill 11111 L , mu,,
1 11 11 ■
^_nll
0 c
1IIII c,
run-in ii c111 ii
cITT!! ...
Fi g. 1 Fi g. 2
cistern, B th e in clin e d g ro o ve d fa ce , C is a sm all stop arran ged so th a t a sh e et of g la ss, or tran sp a ren t niica la id o v er th e in clin e d fa ce will be sup ported and p reven ted fro m slid in g off, D is a series of ste p like cuts m ade across th e ribs b etw e en th e groo ves of the in clin ed face. T h e to p cu t F I I is deeper th an the second b y on e-eigh th of an inch, th e second cu t PG is one-eighth of an inch d eeper th a n th e top of the ribs on th e in clin ed su rface. T h e len gth of the top cut is o n e-q u arter of an inch from th e angle II at the top, d ow p to th e step up F of th e second cu t;
the length of th e secon d c u t is on e-q u arter of an inch from F to G.
The g ro o v es a re o n e - q u a rte r in c h w ide, a n d th e ir vertical sides are o n e - q u a r te r in c h d ee p to th e b eg in n in g
of th e cu rved b o tto m . T h e la tte r is of sem icircu lar cross-section w ith a radius of on e-eigh th inch. T h e ribs m a y be 7/ 32 inch th ick . ■ T h e d o tted line / rep re
sents th e b o tto m of th e groo ves.
F o r use, m ercu ry is poured in to th e cistern A , w hich does not need to be v e r y w ide (say l/ t to */«
inch) and th e th e rm o m e ter is in serted . T h e sam ples of m aterial to be te ste d are pressed in to th e to p m o st p a rts of th e groo ves b etw een F and II so as to fill th e space w hich is shaded in F ig. 2. A b o u t 0.17 gram of asp h a ltu m is need ed for th is. A sheet of glass or m ica is laid on B (to sh u t off cold air d ra fts), and h eat is ap p lied a t E b y m eans of a B u nsen burner. E ach sam ple w ill g ra d u a lly soften and sag dow n th e g ro o ve;
w hen it is liq u id enough to reach from F , its origin al low er b o u n d a ry , to G, a d istan ce of o n e-q u arter inch, th e th e rm o m e ter read in g is ta k e n as th e m eltin g point.
M a rk s m a y be m ade a t in te rv a ls dow n B , sa y a t e v e ry one-half inch and th e b e h a v io r of th e flow ing m aterial as it passes each in succession m a y be stu d ie d as to tem p eratu re and tim e differences.
I t is im p o rta n t th a t th e a m o u n t of m aterial used in co m p a ra tiv e tria ls sh ould be sen sib ly th e sam e. O th e r
wise th e m eltin g p o ints o b serve d w ill differ so m e w h at accord in g to th e re la tiv e sizes of th e sam ples. T h u s in tw o trials, certain sp ecim ens of air-b lo w n petroleu m asp h a ltu m w ere applied in d ifferen tly sized pieces and each series te sted a t th e sam e tim e w ith th e fo llo w in g resu lts:
Me l t i n g Po i n t so f Di f f e r e n t l y Si z e d Pi e c e s o f Pe t r o l e u m As p h a l t u m
S a m p l e N o . 1 N o . 1 N o . 2
R a t e o f h e a t i n g f o r 1 0 ° C ... 7 7 s e c . 1 0 0 s e c - 1 0 0 s e c . S m a l l p i e c e ... 1 8 4 ° C . 1 8 1 ° C . 1 8 3 ° C . M e d i u m p i e c e ... 1 8 0 ° C . 1 7 5 ° C . 1 7 8 ° C . L a r g e p i e c e ... 1 7 8 ° C . 1 7 1 ° C . 1 7 4 ° C .
I t w ill be seen th a t sam ple N o. 1 show ed in one case a difference of 6° C . in m eltin g po int and in th e oth er case of 10° C ., d ep en din g on w h eth er a large or a sm all piece w as used. T h e large p iece of N o. 1 used a t rate 77 sec. w as n ot th e sam e in size as th a t used in rate 100 sec.; th e sam e rem ark applies to th e m edium and sm all pieces. T h e larg e pieces w ere a b o u t th e size of peas, th e sm all pieces a b o u t o n e-th ird this size.
In order to overco m e th is cause of d iscrep an cy th e space in th e upp er p a rt of th e gro o ve should, as a lre a d y said, be filled w ith th e m aterial to be te sted , and th en th e top scrap ed off ev en w ith th e su rface of th e p a rtly cu t off rib. B y th is m eans se n sib ly th e sam e sized sam ple m a y a lw a y s, be su b je cte d to te st, th e re b y elim in atin g one of th e u n ce rtain tie s of th e m eltin g p o in t of th e su b stan ces under consideration .
T h e reason th a t a larger piece ap p ears to fuse a t a low er te m p e ratu re th a n a sm aller piece seem s to be th a t th e actio n of g r a v ity is r e la tiv e ly g rea te r a t th e sam e tim e th a t th e a ctio n of c a p illa rity is r e la tiv e ly less, w ith th e larger piece. T h e first fo rce ten d s to pull th e m ass dow n th e incline, and so to render th e ap p aren t m eltin g p o in t lowrer. T h e secon d force tends to p re v e n t th e liquefied, or sem i-liquefied sam ple from flow ing dow n and, th erefore, to render th e a p p aren t m eltin g point high er. T h ese circu m stan ces
9 4 0 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y V o l. 5, No. 11 n ecessarily o p erate in m ost o th er m eth od s of d ete rm in
ing th e m eltin g p o in t o f th e classes of b od ies under con sid eration . B u t in th is a p p a ra tu s th e va ria tio n s can be co n tro lled b y e x a c tly fillin g th e space as de
scrib ed , w hereas in m ost o th er m eth od s no such co n tro l is as e a sily o b ta in a b le.
A s h as a lre a d y been sta te d m a terial of ind efinite m eltin g p o in t w ill flow a t lo w te m p e ratu re s if g iv en tim e en ough . T im e is th e re fo re an im p o rta n t fa cto r in th is d ete rm in atio n and m u st be ta k e n in to acco u n t.
T h a t th e te m p e ratu re a t w hich su b sta n ces of in definite m eltin g p o in t a c tu a lly fu se depends consid er
a b ly on th e r a te of h ea tin g is illu s tra te d b y th e fo l
lo w in g ta b le :
M e l t i n g Po i n t s o p Ai r- Bl o w n Pe t r o l e u m As p h a l t u m f o r Di f f e r e n t Ra t e s o f He a t i n g
R a te for 10° C. 43 sec. 65 sec. 68 sec. 75 sec. 113 sec. 126 sec.
Sam p le N o . 1 119° C. 114° C. 114° C. 115° C. 112° C.
2 140 134 133 135 KJ00 o p 128
3 157 154 150 149 147 147
4 161 160 156 156 151 150
5 170 169 166 157
I t follow s, if co m p a ra b le resu lts are desired, th a t
I t follow s, if co m p a ra b le resu lts are desired, th a t