Note: Descriptions are shown in the official language in which they were submitted.
238
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This invention relates to a method of gas produc-tion in a
ferrous bath reactor vessel containing a bath of molten iron
to which solid or liquid carbonaceous fuels are fed whilst
a gas iet consisting at least partly of oxygen is blown onto
the top surface of the melt so that the fuels are gasified
and collected in the gas space above the mel-t whence they
are remo-~ed.
The continuous gasification of coal or other carbonaceous
fuels in a reactor containing a bath of molten iron or steel
covered by a layer slag to form a gas consisting essen-tially
of C0 and H2 has been known for a long time. According to
the method described in German OS 29 52 434 oxygen is blown
onto -the top surface of the melt by means of a blasting lance
arranged above the melt surface, thus generating a high-
tempera-ture blasting zone. A jet of a solid, carbon-
containing powder -together with a propellant gas is then
directed at this high ternperature blasting zone.
Another method is described in German AS 25 20 8c83, according
to which coal, or a carbonaceous fuel, is injected into
the ferrous melt at a point situa-ted below -the mel-t surface.
A gas jet which consis-ts at leas-t par-tly of oxygen is also
injected into -the melt beneath the surface thereof, -the jet
being sheathed by hydrocarbons -to pro-tec-t the ~ssocia-ted
nozzles .
Finally, German PS 25 20 868 describes a known process in
23~3
which high-energy-content coal, free carbon, aluminium,
silicon,calcium carbide, or mixtures of these, are additionally
fed into the ferrous bath, potentially indepenclently of the
coal which is to be gasified in -the reactor. This feeds
additional heat into the coal-gasifica-tion process.
A disadvantage of these known ~ethods is that low grade fuels,
particularly those types of coal which have a low calorific
value, could hitherto not be gasified in a cost-effective
manner because an additional supply of high-energy fuels is
needed with fuels of this type in order to maintain the
temperature of the ferrous bath. Additionally, with these
known methods it is not possible to use cheap, directly
available oxidising gases, such as air.
An object of th0 present invention is therefore to minimise
or overcome the disadvantages of the previously known methods
and to provide a method which allows a combustible gas -to
be produced in a cost effective manner from carbon and/or
hydrocarbon-containing fuels of lower energy grades, the
fuels beingsupplieclin solicl, pow~ered or licluicl form to a
ferrous bath reactor with -the assistance of cheap o~iclising
gases in s~lch a manner as to clispense with -the need for an
additional supply of high~energy-content fuels for -thermal
balance compensation in -the gasification process.
Accordingly, the invention resides in a me-thod of gas
produc-tion in a ferro~ls ba-th reactor containinga ba-th of
23l3
molten iron, comprising the steps of feeding a carbon-
containing ~uel in solid or liquicd form into the reac-tor,
and blowing a jet consisting at least par-tly of o~ygen
onto -the top surface of the mel-t, so that the fuel is
gasified, collected in a gas space above the melt and
removed therefrom, wherein -the gas je-t is blown -through -the
gas space, sucks in -the already-produced gases, partially
burns them and -transports them to the melt surface so that
the heat generated by the combustion of the produced gases
is transmitted to the ferrous melt.
In such an arrangement the gas traverses the gas collector
space above the melt sur~ace over a dis-tance o~ maximum
possible length. Due to the jet effect of the gas stream
which is blown into the reactor, the gas whichhas already
been produced by gasification of the fuels in the melt
and is present in the gas space is sucked in-to the jet stream
ancl carriecl along wi-th i-t. This kind of effect can also be
observed with, for e~ample, a wa-ter jet pump. Since -the gas
jet which is blown onto the surface of -the melt contains
o~ygen, a por-tion o-~ the alreacly producecl combustible gases
in the gas space is burnt ancl the resu:lting heat is fed into
-the mel-t because the gas jet clirec-ts the hot comb~ls-tion
products -towards -the me:Lt surface so that the hot combustion
produc-ts coMe into contact -therewith and can -tr~nsmi-t their
heat to t~e mel-t.
The me-~hod according to this inverltion of blowlng a jet
3lZ38
stream of a gas which has an o~idising effect (i.e~ ox~gen,
air or the like) a-t the surface of the melt affords a sub-
stantial improvement in the thermal balance of a ferrous
bath reactor.
The method according -to -the inven-tion also allows the use
of air for thè gas je-t. It is therefore no longer
necessary to use technically pure oxygen, as in conventional
processes. Air is generally very cheaply available and can
be compressed to the required operative p~essure by simple
means. It is particularly recommended to pre-hea-t the
air in order to avoid heat being extracted from the
gasification process for the preliminary heating up of the
injected air. In practice, a pre-heating temperature of
300 to L~oO C has been found to be suitable. Up -to this
temperature level it is possible to use conventional
pipelines and valve means and the cos-ts of thermal insu-
lation in the s~lpply system are acceptable.
~lowever, i-t is also possible -to use pure oxygen as -the gas
je-t. This has particular advantases when working with
fuels having very low hea-ting power. Thus, the percentage
of oxygen in the gas je~ is determinecl by
considera-t:ions of cost and by -the quali-ty of the fuels in
cluestion .
Preferably, the fuels, in solid or liquid form, are injec-ted
into the melt a-t a position below the mel-t surface~ The
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fuels are injected by means of propellan;t gases such as,
for example, air, nitrogen, carbon monoxide, ancl inert gas
or the like. However, it is equally possible to feecl the
fuel into the reactor above -the mel-t surface.
The oxygen in the gas stream which is directed through the
gas space an~ onto the surface of the melt is specifically
intended for the combus-tion of a portion of the gases which
are produc.ed from the fuel. The supply o-f oxygen for the
actual gasification process as such, on the o-ther hand, is
preferably made through nozzles arrangecl beneath the melt
surface. These nozzles may for example consist of several
concsntric pipes, and a hydrocarbon may besupplied for
nozzle protection in a known manner.
The proportional amoun-t of oxygen fed ~eneath the melt
surface relative to -the proportional amount of oxygen
contained in the gas je-t which is directecl at the surface
of -the melt may be varied within very wide llml-ts. ~or
e.~ample, 80 % of the total amoun-t of oxygen may be fecl from
above -through the gas jet ancl only 20 % lnjec-ted beneath
the melt surface, or conversely, 80 % of the -total amount
of o~ygen supplied to -the .ferrous bath reac-tor rnay be
lnjectecl benea-th -the surface of -the melt and on].y 20 %
adderl from above ln the form of the gaseous jet s-tream.
However, lt has been found -that in orcler -to obtain the
aclvarltages of the i.nvention in respec-t of -t:hermal econorny
at leas-t 10 % of the tot.al amount of oxygen fe~ in-to the
23~
reactor snould be blown as a gas jet onto the melt surface
in the reac-tor vessel. This percentage may be increased up
to 100%, and it has been found, surprisingly, that this
oxygen in the gas je-t also serves -to oxidise -the fuel in
-the ferrous melt. In normal operation of a ferrous-bath-
reactor approxima-tely ~0 to 90% of the -to-tal amoun-t of
oxygen would be supplied through the gas je-t. For reasons
of economy alone the amount of oxygen which is fed into the
melt from above will be chosen tobe ~shigh as possi~ae, because
this fraction of the total oxygen supply is generally injected
at a lower pressure than that which is required for oxygen
injec-tion through the nozzles situated beneath the melt
surface.
Preferably, several gas jets are directed at the melt surface.
The gas je-ts are arranged -to enter the reactor vessel at a
large dis-tance from the top surface of -the bath and to
impinge approximately in the central area of the bath
surface. :[t is impor-tant -that -the gas jets should cover a
sufficiently long dis-tance in the gas space above the mel-t.
~ormally a minimum distance of abou-t 2 m should be maintained
between -the gas jet nozzles and the surface of the ferrous
bath. The nozzles are mounted in the refrac-tory lining in
the upper region of the reactor vessel. Particularly in -the
case of air injec-tion, each nozzle may consist of a simple
pipe, or else, for example for injec-tion of pure o~ygen, of
two concentric pipes. ln the lat-ter case the o~ygen flows
through the inner pipe and, for nozzle protection, small
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amo-unts (0.1 to 5% relative to the oxidising gas) of
nitrogen, carbon monoxide, an iner-t gas, a hydrocarbon or
the like, are injectecl through the annular gap between the
concentric pipes.
Accorcling -to a preferrecl embodime-nt of the me-thod
accorcling to this invention, a gas, which i3 largely sulphur-
free, is produced from sulphur-con-taining fuels in the ferrous-
bath-reactor for subsequent combustion in boiler- and heating
plant, for exarnple for elec-tric power generation. The sulphur
is removed in the reactor by a slag which contains CaO. The
necessary slag-formers, in particular CaO, are delivered,
preferably in powder form, with the oxygen-containing gases
which are injected into the melt below the surface thereof.
It is also possible to admi~ the slag-formers with the
fuels, or to inject CaO spparately with the aid of a
propel.lant gas. The resulting slag, including -the enriched
content of -fuel ash co.n-tained therein, may be d:rawn off
batchwise from the reactor, or it may be des-llph~.lrised in
molten concli-tion for improved thermal economy accord:ing
to Germcln Pa-tent 25 20 58l~, ancl large:ly returnecl in mol-ten
conditio:n -to -the reactor.
For e.~ample, by app:Lication of the me-thod according to this
invention, depending on the -type o e fuel fed into -the
reactor, gases have been produced of the follor,~ing composi-
tion. For the gasification of 1 -t coke con-taining about
lO~o ash and 1% sulphur, approximately 2~00 m3 of air which llad
been preheated-to atemperature of300C wasinjected in-to-the ferrous
2;~
meltbeneath themelt surfacéand at-the same time 2 400 m3 ofair
which had been preheatedto thesame tempera-turewas blown on-to
the -top surface of the melt. The ferrous mel-t hacl a tempera-
ture of approximately 1400 C and a carbon content of about
2~ou For each -tonne of coke 5 500 m3 of gas were obtained,
consisting of approximately 25% CO, appro~ima-tely 6% C02,
approxima-tely 69% N2 and approximately 0.002% sulphur, at
a temperature of 1400 C. The gas con-tained a clust frac-tion
of about 2 g/m3 and could be fired directly in a boilex plant.
The gasification of a long-flame gas coal containing 78% C,
5% H, 7% O, 5% ash, produced a gas of the following composi-
tion: 19.0% CO, 4.8% H2, 4.6% C02, 66.5% N2.
A lol~-energy, dried lignite product with 64.o ,~ by weigh-t
C, 4.9% by weight H, 23.6% by weight 0, 5.9% by weight ash,
0.4% by weight sulphur and a heating value H of 5600 kcal,
which was gasified wi-th air at 300 C in the ferrous-ba-th-
reactor in accordance with -the method of this inventiorl,
prodtlcecl a gas con-taining 21.~ vol% CO, 6.2 vol.%H2, 5.~
vol.% COz, 6.2 vol.% H2o,60.7 -~rol.% N2, 20 ppm sulptltlr and
a heating value of 806 kcal/m . I~or clesulphuri~ation
approximate:Ly 9 kg CaO / t coal were fed in-to the ferroas
bath-reac-tor.
The application of oxygen in accorclance with this inven-tio
is always found to be advan-tageous where -the demand for a
high-energy content gas wi-th low N2 content ls of primary
importance or where particularly low energy f~l~l grades are
23~1
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used for gas production in the ferrous bath reactor.
~hether pure oxygen, or oxygen-carrying gases, and in the
latter case, which such gases, are used for gasification in
the reac-tor clepends primarily on economic considera-tions
and on the envisaged fur-ther application o~ -the produced
gAses. According -to the method of -this inven-tion there are
no method-technology problems encountered in the gasification
process and i.n -the compensa-tion of energy requirements in
-this process due to the partial combustion of the produced
gas in the gas collecting space of the reactor and the
application of different oxygen-beari~g media.
According to a further, particularly advantageous modi.fication
of the invention substances which contain iron, in bonded
or -free form, such as, for example iron ore, are added to
the melt in the reactor vessel for the purpose of simul-
taneously producing molten iron (pig iron) and a gas.
Accordingly, with -this modifica-tion of the inven-tion, the
heat generated by the par-tial pos~t-combus-tion of the gas
which is produced in -the ferrous mel-t reac-tor is utllised,
a-t leas-t partially, for recluction of the iron-con-taining
substances, particularly iro:n ore. Thus, in this rnodification,
besides the carbon-con-taining solid or liquid fuels as ~ell
as oxygen and slag-forming materials, further ma-terials
which contain iron at least partially in oxicle form, such
as for example iro:n ore, are added to the ferrous melt in
the reac-tor vessel. An impor-tant economic a.dvan-tage of -this
modification of the method according -to the presen-t invention
z~
resides in -the fact that ore is direetly reduced at lo~
teehnical expense and ou-tlay by a relatively small quantity
of eoal and at the same time a gas is generated whieh has
many potential applieations. In one example o-f this
rnodifieation, to produee one tonne of iron by reduetion of
iron ore, approxirrlately 1.1 t of eoal (eomposition appro~i-
mately 78% C, 5% H2, 3% H20, 5~0 ash, 5% 2' 1% S, ealorifie
outpu-t value Hu = 7.500 kcal/m3) are required. The
simultaneously produced gas is suitable for incLustrial use
and has approximately -the following eomposition: 57% C0,
1~% C02, 14% H~ % ~I20, with a heating value Hu of about
2.100 kcal/m3. The method aeeording to this modifieation
thus enables the eeonomie optimisation of the produetion of
iron in eombination with gas produetion in a ferrous bath
reaetor. By way of eontrast, if the method of said one
example is repeated but without the feedba.ek of energy from
the partial post eombustion of the gases whieh are produeed
in the ferrous melt, aeeording -to this invention, approx:i-
mately 3 t of the same kind o-f eoal are needed to produee
1 t of iron from the ore. The produeer gas woulcl then
`have the followi.ng composi-tion: 70% C0, 1% C02, 27% H2,
1% H20, with a hea-ting value ~u of abou-t 2.700 kcal/m3.
0-ther known multi-stage methods for -the reduc-tion of iron
ore and the procluction o:f molten iron, for e~arnple according
to German OS 24 01 909, have -the clrawback -tha-t the gas
~hich is p:roducecL in s-uch a process, clue to i-ts :I.ow heating
value, ean be usecL only for minor heatlng functions without
- 12 -
incurring the cost penalty of adding high-energy gases.
With -this process approximately 650 kg of coal are needed
to produce one tonne of iron and -the gas which is produced
comprises approxima-tely ~1% C0, 30% C02, 18% H20, 10% H2,
with a hea-ting value of 1.100 kcal/m3.
In this modi~ication of the present inven-tion, -the ore may
be fed into -the ferrous mel-t directly through bottom nozzles
or also from above by blowing it at the surface of the melt.
In a preferred embodiment, the ore is at least partly added
jointly with -the o~ygen which is blown at the mclt surface.
In this case the pulverised ore is already pre-heated and
pre-reduced in the gas atmosphere which improves -the thermal
efficiency of the process. To further improve this effect
it may be advisable to provide the blasting nozzle with
maans for e~panding -the jet containing the ore particles,
for example by imparting a spin to the je-t as it leaves -the
nozzle.
Bes:icLes ores of VariO~LS qua:Lities, pellets and briquettes
of incomp:Lete:Ly reducecl ore are founcl-to be particularly
sui-table chQrge materials containing iron a-t least par-t]y
in an oxicle form.
The IDethod ~ccording -to the present invention may be
advan-tageously applied in all situations ~rhich allow the
produced gases to be used as fuel ~as in the :immediate
~icinity, for ins-tance as a s~lbstitu-te for natural gas.
The partially burnt gas which is produced in the process
accorcling -to the invention has approximately the same
flame temperature as natural gas, mainly due to its
rela-tively high CO-conten-t, so tha-t i-t can be substi-tu-ted
for natural gas wi-thou-t major conversion of f~rnaces and
their burner devices.
The following example describes the application of the
method according -to this invention to a converter--type
reactor vessel containing 60 t of ferrous melt. The base
of the converter is provided with ten nozzles having an un-
obstructed diame-ter of 28 mm. Through two of these nozzles
pulverised coal dus-t is injected at the rate of 350 kg/min,
the propellant gas being either nitrogen, carbon dioxide
or even reduction gas from the converter i-tself. Oxygen is
injected -toge-ther wi-th iron ore -through three nozzles whilst
the remaining five nozzles are used for injec-ting oxygen
partially charged with slag-formers such as for example lime.
A further nozzle is providecl in the upper co~:ical par-t of
the conver-ter through which appro~:ima-tely 50% O:e -the total
o~ygen reqlliremen-t is directecl a-t the top of the me1t. Using
coal of the above specifiecl composition and an ore con-taining
85% ~`e203, 20 -t of iron wi-th a carbon con-tent of abou-t 3
is produced per hour. The o~ygen requirement for the
gasification of one tonne of coal simul-taneously Witll the
smelting of 1.~-~50 kg ore amo~mts to 580 m3. The process
produces a carbon- or fuel gas having the above specified
analysis (about 57% CO, 11t% C02, llt% H2, lLt% H20) and a
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4 --
heating value Hu of approximately 2.100 ~cal/m3.
I-t is also wi,-th:in -the scope cf this in.vention -to design
the reactor vessel in such a shape -that it may simultaneously
serve as a conver-ter so that steel can be directly produced
in the same vessel. To this end the carbon con-tent of
abou-t 2 to 3%, which exists during normal operation of the
ferrous melt reactor, is lowered to a'bout 0.05% prior to
each tapping operation whereafter about 20 t of the melt is
tapped from the converter. A melt of approximàtely 50 t is
then left in the conver-ter and is subsequently slo-wly re-
carbonised -to the desired carbon content of 2 to 3% in
the course of con-tinued simultaneous blasting of o~ygen and
coal with a small e~cess of the latter. When working in
this manner it has been found to be advisable to remove the
slag from the melt before the carbon of the mel-t has fully
returned to i-ts original value, i.e. appro~ima-tely when the
residual carbon content in the melt is be-tween 0.5 an,d 2%~
The subsequently newly formed fresh slag which .Ls in 'balance
w,ith the tapped steel me:l.t then remains in -the conver-ter.
The me-thod accorcLing -to thi.s i.nvention is he:reinaf-ter more
particularly descri'becl with reference to ~.n embocliment
and with -the aid of the accompanying draw:irlg which represents
~ longitucllnal sec-tion through a ferrous ba-th reactor.
P~eferring -to -the drawing, a conver-ter-shaped reac-tor vessel
20, which is sealed in gas-tish-t manner, is filled to abou-t
hal:f of its capacity wi-th a ferrous melt 21, -the surface of
- 15 -
the melt 22 extending approximately hal-fway up the height
of the vessel 20. A nozzle 23 is provicled in the base of
the reactor vessel for the injection of finely-subdivicded
coal 2~. Also arrangecl in -the base of the rcac-tor vessel
20 is ~n oxygen injection nozzle 25 -thro~lgh which oxygen
is injected into the melt 21 separately from the nozzle
23. In practice this oxygen nozzle 25 will be surrounded
by an ~nnular gap for the injection o~ hydrocarbons or
the like for nozzle protection.
In the upper region of -the converter two nozzles 26 and 27
extend through the walls of the reactor vessel 20. They
are supplied with air 28 and form jets 29 which are
directed approximately at the central region of the melt
surface 22. The outlet orifices of the jet nozzles 26 and
27 are situated approximately 2 m above -the melt surface 22.
The gas jets 29 travel -through the gas space 30 above -the
rnelt surface 22 and by -their je-t ac-tion suck in ancl cLrag
alon~ a portion of the gases 31 a:lreacly genera-tecl by
gasifica-tion of -the fuel coal '~4. /~ fraction of these
gases 3:l is burn-t by the oxygen content in the gas je-ts 29.
The combus-tion hea-t is transmi-ttecl throug:h the mel-t surface
22 -to -the ferrous rnel-t 21.
