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Патент USA US2404328

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July 16,194&
2,4o4,32s4
` u. J. TURlN ET AL
FUEL FIRED VACUUM FURNACE
Filed Nov. 30, 1944
' %731.
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Peter'
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Patented July 16, _1946
2,404,3Z8
UNITED »STATES V PATENT “OFFICE?? _ I
FUEL FIRED VACUUM FURNACE
John J. Turin, West Newton, Mass., and Arthur
W. Peters, Toledo, Ohio, assignors, by mesne as
signments, to surface Combustion Corpora
tion, Toledo, Ohio, a c'orporation' of Ohio
Application November 30, 1944, Serial'No.~.565,936
8 Claims. (CI. 266-15)
1
9
2
e
The present invention relates to the manufac
ture of metallic magnesium by the thermal re
duction of magnesium oxide and more particu~
V dium. to the-cylinder being indioated'at?6a.i-„.'I'he
larly to an improved vacuum furnace for use in
“ reducing zone of the furnace presently .described.
connection with such manufacture.
In the ther-mal reduction of magnesiumoxide
with a reducing agent like ferrosilicon, it is cus
tomary to form the reacting ingredients into rela
tively small briquettes and then to heat these
briquettes to reducing temperature in a vacuum.
Heretofora'in the case of fuel ?red furnacevs,
it has been customary to effect the reduction of
the' magnesium oxide on externally-heated, vac
uum-tight retort. However, the upper tempera
ture limit of the retort has been only about 2100
2150° F. due to the retort beingmade of` a heat
A ball of the condensed? magnesiumisindicated
resisting alloy (a chrome ,nickel iron alloy) which
at said temperature' is 'semi-plastic and readily
purpose of thiscylinder 6 is to serve-as a ‹con-`
denser for magnesium vapor coming„f.rom„the
in broken lines at M.
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„
To facilitate handling ,of theload constituted
by_ the. closure 3 and. the-parts .Suspended .there
fromr the closure is hung on anarm 36-01 athori
zontally disposed. beam af?xed „to..anv elevator
post' 31 mounted in a.support, 38- securedLtothe
exterior 'shell of the furnacel An hydraulic?cylin
der for raising and lowering the-post 31 isdia
_ grammatically indioated. .atr39. ,A spare closure
3a .withcondenser cylinder 6'‹ attached is?hung`
from the opposite arm' 360ofthesaidfbeaml.`
The magnesium vapor whichcondenses. on?the
oylinder 6 comes from acharge hof› briquettesv_ in
an upright retortor container 20 in the lowerpor
there is required some hours to effeot satisfactory 20 tion Za, _of the furnace, this r› vapor passin-gout
of the reto'rtthrough atopaperture H and thence
reduction of the magnesíum oxide whereas'at a
into an upright drum or barrel 9 which consti
temperature of only a few hundred.) de'grees
deformable.
At a temperature of 2100-2150° F.
higher, reductíon can be e?ected more' completely
and in substantially less time.
'The present invention has for its object to pro
tutes in effect a vapor collecting chamber. whose
temperature may .be controlled by electric ,heat
25 ing elements 30 disposed, around the outsiderof
vide a fue] ?red furnace which shall make it pos
sible to heat the 'said briquettes of magnesium
the barrel. The briquettes are lintroduced- into
the retort 20 through the top aperture_ ,l i, it being ,
oxide containing material to reducing 'tempera
understood that the briquettes will ?rst have been
dumped into the drum 9 before the closure 3 is
ture without the use of an 'externally ?red vac
uum-tight retort and Withal to permit such heat 30 in`p1acef Before being dumped into the drum 9
the briquettes will have been `prelí?eated to a tem
ing to be effected more speedily and e?iciently
perature ofy'about'1200-1300° F. for the purpose
than has heretofore been possible with fuel ?red
of drying› and degasifying the same. To permit
apparatus. Other related objects will more fully
the briquettes to be temporarily held in the drum
appear hereinafter.
.
v For a consideration of what' we believe to be s 9 until the retort 20 has been made fully ready
to receive them, there is provided above the aper? r
novel and our invention, attention is directed?to
the following »speci?cation and the claims ap
tur?'ll a stopper l_2 adaptedyto be operated by a
rod' l3 extending upwardly therefrom to an op;
pended thereto.
`
erating lever'M. 'A hood`l6 above the stopper
In the drawing: `
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Fig. 1 is a vertical sectional view with parts in
elevation of a furnace embodying the present in
vention.
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Fig. 2 is a horizontal sectíonal view on line '2-2
of Fig. 1.
i
The improved furnace comprise's a Vacuum
tight exterior metal shell or. casing 2 comprised
prevents jamming'of the stopper by the briquettes
thereabove. The hood'is?held in ?xed position
by'radial 'struts 16'. In thedrawing; the stopper
is shown in down or' closed position. i The lever
|4 is connected to' avacuum-tight Operating 'de
? vice I5.outside of the'furnace shell.
The'lower end of' the drum 9 rests'on the top
of lower and upper portions ?a and 2b respec
wall IO of the retort'25` and its upper end is" slid
tively, the shell having an interier lining 'I of
heat insulating material. The top of the› oasing
theclosure 3 is protected 'against overheating?by
ably 'centere'dlin the collar 2c. The underside of
hasa central opening encompassed by` a collar 50 a circular body 3' of heat insulating materialícar
ried thereby and adapted to project a short dis
Zc, this opening being normally closed vacuum
tight by a cap type closure Sadapted to seat on
tance into the drum 9. A `vertical groove in said u
body :permit's free movement of the rod l3. Ex_
said collar.
_ _
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ç
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tending-laterally from the collarv 20 is a conduít
An internally cooled cylinder 6 .depends from
the closure 3 the pipe „which delivers cooling me
5 which serves to connect the interior ofthe; fur_
3
4
pump.
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readily absorb heat from the ?aming fuel.
The mode of operation of the improved fumace
i
The bottom of the furnace shell or casing 2 has
`a central opening encompassed by a collar 2d,
this opening being normally closed vacuum-?ght
may be brie?y summarized as follows: The re
5
by a closure? 4 adapted to seat on the collar. A
cylinder 4' of heat insulating material'on the
closure closes the bottom of the retort. To per
mit'ar'waste receiving car to be dí'sposed ,beneath
the furnace, the latter is mounted on stand-" 10
ards 35.
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the spacers 2| is preferably serrated to more
nace to a source of vacuum such as a vacuum ?
3
fractory structure 8 is' heated to a temperature,
of about 2700° F. before a vacuum prevails in the
firing space 40' or, in other words, before a Vac
uum prevails within furnace shell or?ca'singi 2.
Breparatory to producing a vacuum within the
furnace the bumer 22 must, of course, be shut off
vvacuum-tight. Also a charge of preheated bri
quettes Will have been dumped into the drum or
To facilitate handling of the load _constituted
barrel 9 in the upper part 'of the furnace pre
by the closure 4, the closure is mounted on an
paratory to being dumped into the retort 20 as
arm 3| of a horizontally disposed ,beam af?xed'to ?
an elevator post 32 mounted in a support 33 af_ 15 soonas the bottom closure 4 is in place and ?the
furnace is otherwise ready to be evacuated. As
?xed to the furnace casing: An hydraulic cylin
soon as the briquettes have been dumped into the
der for raising and lowering the post is »diagram
furnace the furnace is made yacuum-tight and
matically indicated at 34. A spare closure 4a is'
the vacuum pump started. Heating up of the ,
mounted at the opposite arm 131 i of said beam.
g The retort 20 is made of réfractory material 20 charge of -briquettes in the retort takes place rela
tivelyquickly due to the highly heated structure
adapted to stand a temperature in the neighbor
-8 around the retort. The"evolving'magnesium
hood of 2700D F. and which will not react with
vapor?ows out of the retort and into the' col
magnesium vapor. The Dreferred material for
lecting drum 9 thereabove by way of the con
this purpose issilicon carbide, but alundum and
magnesite may be used. Between _its top and 25 necting passage M and condenses on the con
bottom walls the retort is preferably comprised ` denser 6, it being understood that the drums!) is
maintained at a su?iciently high temperature by
of a circumferential series of intercomn?unicatipg
the surrounding electric heating elements to pre
? i relatively narrow upright Channels !8, four such
vent the vapor from condensing on the walls of
channels being shown. it being understood that
the
drum. After a predetermined time interval
30
briquette's dumped into the retort will ?ll these
the vacuum within the furnace is broken to permit
channels. thereby substantially reducing thehori~
removal'of the top closure 3 to permit removal of i
zontal distance. that heat must_ travel radially
the
condensed magnesium from the condenser 6;
' inward to reach the center of the charge.
The furnace is then again made ready `for an
The *retort 20 is surrounded by a refractorv '
structure 8 _comprising an' outer'circula'rwall j|9
spaced from' the retort to form a ?ring or com
bustion space 40 about the retort. This structure
8` is preferably made of silicon carbide. and is 'so
massiveithat after it has been heated. to a tem
perature of about 2700° F. it will contain enough 40
heat not only to heat the charge of briquettesin
the retort to reducing temperature but also 'to
sustainthe endothermic reaction fort a period
_long enough to e?e'ct substantially complete re
duction of the magnesium oxide.
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A burner 22 is positioned in the furnace wall
to ?re 'tangentially into ,said ?ring space 40
whereby to heat said structure `8 to the'said- ele
other charge by reheating the structure 8 a's _will
now be readily understood. ?In the meantime, the
'bottom closure 4 is removed to permitthe 'spent
charge of briquettes in the retort to drop out of
the furnace into a waste receiving car beneath
the furnace.
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From _the foregoing it will be seen that' the
present invention provides a relatively simplegand
practical fuel ?red vacuum furnace which is well
' adapted for its intended purpose. '
The present application is a continuation 'in
part of our application Serial No. %55,260 ?led
August
18',
1942.
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What
1. In appa'ratus
is claimed for
as new
the is:
thermal
~ ` treatment
› in
vated temperature, it being understood that this 50 a\ vacuum of a magnesium oxide containing ma
?ringiis done only when -atmospheric pressure
terial capable of evolving magnesium vapor, 'the e
prevails within the furnace casing 2 and that the
ccmbination which comprises a relatively tall
.burner will be shut off vacuum-tight when 'a
heat conducting refractory structure de?ning a
vacuum prevails in said furnace. `lnrlí'iggz, the
fuel supplyipipe for the burner is indicated' at 23,
the same „being provided with aivacuum-tight
shut-off valve 24. The burners may be lighted by
inserting a torchthrough a lighting' passage› 25
which, is normally closed vacuum-?ght by'a clce
container for a charge of said material, the said
structure being chambered to provide a combus
tion space, burner means for delivering fuel to
said combustion space for heating said structure
to anielevated temperature substantialiy higher
than 72100° F. before producing a vacuum' in said ,
sure 25'. Thewaste heating gases ?ow'from the
combustion› space 40 through a lateral port 28 to
a waste gas ?ue 27 which is normally'closed
chamber, a vacuum casing wherein said structure
is housed and wherein a vacuum must prevail in
vacuum-tight by a closure 29.
duringrthe therinal treatment of said material,
,
-
As shown inFig. 1, the ?ring space 40 is pref
order that a vacuum may prevail in said container
said structure being so massive that when it 'has
erably divided into a vertical series of communià 65 been heated to said elevated temperature there
cating compartments by hori'zontally disposed re
Will be present in said structure all of the 'heat
?ractory spacers -21, each having an aperture 2l'
required to react the 'oharge of said material in
so arranged› with respect to the aperture in the
said container, and said container having a cir
next adjacent'spacer that the fiaming fuel from
the burner 22 must necessarily ?ow in 'a circui
tous path in flowing upwardly to the waste gas
?ue 21. Although only one burner has been
shown, 'it' will? be readily understood that there
maybe a'vertical r?ow of such burners. As shown r'
in Fig. 1, the'inner? face of the'wall ?9 between
e cumferential series of relatively'narrow upright
reentrant channels for the reception of? thesaid
material.
`
2; In apparatus fior the thermal treatmentrof
›material‹under vacuum, the, combination 'which
'compri?es a'refractory structure de?ning a non
Vacuum?tight container wherein a charge of said
2,4o4,328
5
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material will be placed for heating to treating
temperature, a vacuum-tight casing wherein said
perature there will be present in said structure
structure is housed and wherein a vacuum must
prevail in order that a, vacuum may prevail in
said container, said refractory structure being so
at the said 'treating temperature, the said struc
ture being chambered to provide a combustion
space about said container, burner means for de-?
massive that when it has been heated to an ele
livering fuel to said combustion spacefor heating
vated temperature substantially higher than the
said treating temperature there will be present
ail of the heat required to maintain said charge e
said structure to said elevated temperatureibefore
' producing a vacuum in said casing, and means
at the bottom of the said apparatus permitting
in said structure all of the heat required to main
tain said charge at the said treating temperature, 10 waste material in said container to be discharged
the said structure being chambered to provide a
{6. In apparatus for the thermal treatment'in a
combustion space about-the 'said container, and
i vacuum of material capable of evolving magnesiburner means for delivering fuei to said combus
um vapor, the combination which comprises a
tion space forheating ,said structure'- to said ele
refractory structure de?ning a non-vacuum tight
vated temperature before producing a vacuum in
container for a charge of said material, the said
said casing.
structure being chambered to provide a combus
3. In apparatus for the thermal treatment of
tion space about said container wherein fuel may
material under vacuum, the combination which
be burned for heating said structure to an ele
comprises a reiativelytall refractory structure
vated temperature of about 2700° F. before pro
de?ning an open top container wherein a charge
ducing a vacuum in said container, burner means
of said material will be placed for heating to'
fordeliveríng said fuel to said combustion space,
treating temperature, a vacuum-tight casing
a vacuum casing wherein said structure is housed
wherein said structure is housed and wherein a
therefrom.
vacuum must prevail in order that avacuum may
prevail in said container, said refractory struc
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and wherein a vacuum must prevail in order that
a vacuum may prevail in said container, said re~
fractory structure being so massive that when it
ture being so massive that when it has been heat
has been heated to said elevated temperature
ed to an elevated temperature substantially high
er than the said treatir?g temperature there' will ' there will be present in said structure all of the
heat required to maintain the said charge at mac'
be present in said structure all of the heat re
quired to maintain said charge at the said treat- ' nesium-evolving temperature, and means in said
ing temperature, the said structure being cham
apparatus for condensing the magnesium vapor
bered to provide a combustion space about the
said container, and burner means for delivering
fuel to said combustion space for heating said
evolving from said charge.
v
structure to said elevated temperature before pro
7. In apparatus for the thermal treatment in a
vacuum .of a magnesium oxide containing mate
rial capable of i evolving magnesium vapor, the
ducing a vacuum in said casing.
combination which comprises , a relatively tall
heat conducting refractory structure de?ning a
4. In apparatus for the thermal treatment of
container for a charge of said material, the said
material under vacuum, the combination which
structure being chambered to provide a combus
comprises a relatively tall refractory structure
de?ning an open top container wherein a charge 40 tion space about said container wherein fuel may
be burned for heating said structure to an ele
of said material will be placed for heating to
vated temperature substantially higher than
treating temperature, a vacuum-tight -casing
2100° F. before producing a vacuum in said cham
wherein said structure is housed and wherein a
ber, burner means for delivering said fuel to said
vacuum must prevail in order that a vacuum may
prevail in said container, said refractory struc
ture being so massive that when it has been heat
ed to an elevated temperature substantially high_
er than the said treating temperature there will
be-present in said' structure all of the heat re
quired to maintain said charge at the said treat- *i
ing temperature, the said structure being cham
bered to provide a combustion space about said
container, burner means for deiivering fuel to
said combustion space for heating said structure'
to said elevated temperature before producing a
vacuum in said casing, a chamber in said casing
in communication with said container, and means
combustion space, a vacuum casing wherein said
structure is housed and wherein a vacuum must
prevail in order that a vacuum may prevail in
said container during the thermal treatment of
said material, said structure being so massive
that when it has been heated to said elevated tem
perature there will be present in said structure
all of the heat required to react the charge of
said material in saidcontainer.
8. In apparatus for heat treating material in a
vacuum, the combination which comprises a re
fractory structure de?ning a container for said
material, the said structure being chambered
operable to permit a charge of said material to
be temporarily retained in said chamber pending
the making ready of said container to receive said
to provide a combustion space about said con
tainer wherein fuel may be burned for heating ,
charge.
stantialiy higher than the treating temperature
5. In apparatus for thermal treatment of ma
terial under vacuum, the combination which com
to which said material is required to be heated,
prises a relatively tall refractory structure de?n
ing a relatively tall non-vacuum tight container :r
wherein a charge of said material will be placed
for heating to treating temperature, a vacuum
tight casing wherein said structure is housed and
wherein a vacuum must prevail in order that a
vacuum may prevail in said container, said re
fractory structure being' so massive that when
it has been heated to an elevated temperature
substantially higher than the 'said treating tem_
said structure to an elevated temperature sub
so that the heat emanatíng from said structure
when a vacuum prevails in said container will
suf?ce to heat said material to the required treat
ing temperature, and a vacuum casing wherein
said structure is housed and wherein. a vacuum
must prevail in order that a vacuum may prevail
in said container during the heat treatment of
_said material.
JOHN J. TUEIN_
ARTHUR W. PETERS.
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