U.S. patent application number 13/519104 was filed with the patent office on 2012-12-27 for method and device for providing reduction gas from generator gas.
Invention is credited to Robert Millner, Josef Stockinger, Johann Wurm.
Application Number | 20120326363 13/519104 |
Document ID | / |
Family ID | 43844614 |
Filed Date | 2012-12-27 |
United States Patent
Application |
20120326363 |
Kind Code |
A1 |
Millner; Robert ; et
al. |
December 27, 2012 |
METHOD AND DEVICE FOR PROVIDING REDUCTION GAS FROM GENERATOR
GAS
Abstract
A method for providing reduction gas for iron ore reduction by
cooling and dry dedusting generator gas produced in a melter
gasifier for pig iron production, as well as a device for carrying
out such method, are provided. The generator gas may be cooled both
by water injection and by heat exchange after it has been
discharged from the melter gasifier and before a dry dedusting
thereof.
Inventors: |
Millner; Robert; (Loosdorf,
AT) ; Stockinger; Josef; (Luftenberg, AT) ;
Wurm; Johann; (Bad Zell, AT) |
Family ID: |
43844614 |
Appl. No.: |
13/519104 |
Filed: |
November 17, 2010 |
PCT Filed: |
November 17, 2010 |
PCT NO: |
PCT/EP10/67616 |
371 Date: |
September 7, 2012 |
Current U.S.
Class: |
266/44 ;
266/147 |
Current CPC
Class: |
C21B 2100/64 20170501;
Y02P 10/134 20151101; C21B 2100/44 20170501; C21B 2100/66 20170501;
C21B 13/0073 20130101; C21B 2100/60 20170501; C21B 13/002 20130101;
C21B 13/143 20130101 |
Class at
Publication: |
266/44 ;
266/147 |
International
Class: |
C21B 3/02 20060101
C21B003/02; C21C 5/40 20060101 C21C005/40 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2009 |
AT |
A2035/2009 |
Claims
1. A method for providing reduction gas for iron ore reduction by
cooling and dry dedusting generator gas produced in a melter
gasifier for pig iron production, comprising: cooling the generator
gas both by water injection and by heat exchange after it has been
discharged from the melter gasifier and before the dry dedusting
thereof.
2. The method of claim 1, wherein the heat exchange is effected
using a liquid heat exchange medium.
3. The method of claim 2, wherein the liquid heat exchange medium
comprises water.
4. The method of claim 1, wherein the liquid heat exchange medium
comprises thermal oil.
5. The method of claim 1, wherein the water injection is effected
before the heat exchange.
6. The method of claim 5, wherein the inlet temperature of the
liquid heat exchange medium lies within a temperature range between
a minimum temperature of 70.degree. C. and a maximum temperature of
450.degree. C.
7. The method of claim 1, wherein the water injection is regulated
in accordance with the temperature of the generator gas after the
heat exchange.
8. The method of claim 1, wherein the water injection is regulated
in accordance with the temperature of the reduction gas produced by
the dry dedusting.
9. The method of claim 1, wherein the quantity of heat withdrawn
from the generator gas per unit of time during the heat exchange is
regulated by changing at least one of (a) the temperature of the
heat exchange medium and (b) the quantity of heat exchange medium
supplied per unit of time.
10. A device for providing reduction gas for iron ore reduction by
cooling and dry dedusting generator gas produced in a melter
gasifier for pig iron production, comprising: a reduction reactor
for reducing iron ore by means of a reduction gas, and a melter
gasifier for producing generator gas by gasifying carbon carriers
in the presence of oxygen and pre-reduced iron carriers, wherein
the melter gasifier and the reduction reactor are connected by a
gas line, a dry dedusting device arranged in the gas line, a water
injection device and a heat exchange device arranged in the gas
line between the melter gasifier and the dry dedusting device, both
the water injection device and the heat exchange device being
configured to cool the generator gas after it has been discharged
from the melter gasifier and before reaching the dry dedusting
device.
11. The device of claim 10, wherein the device for heat exchange
comprises with a feed line for liquid heat exchange medium.
12. The device of claim 10, wherein the water injection device is
arranged between the melter gasifier and an end of the heat
exchange.
13. The device of claims 10, wherein the heat exchange devices
comprises a cooling jacket heat exchanger.
14. The device of claim 13, wherein the cooling jacket heat
exchanger comprises a cooling jacket with a helical guide for heat
exchange medium.
15. The method of claim 1, wherein the water injection is effected
before and during the heat exchange.
16. The method of claim 5, wherein the inlet temperature of the
liquid heat exchange medium lies within a temperature range between
70.degree. C. and 150.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/EP2010/067616 filed Nov. 17,
2010, which designates the United States of America, and claims
priority to AT Patent Application No. A2035/2099 filed Dec. 23,
2009. The contents of which are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a method for providing
reduction gas for iron ore reduction by cooling and dry dedusting
generator gas produced in a melter gasifier for pig iron
production, and also to a device for carrying out the method.
BACKGROUND
[0003] In a number of melt reduction methods for iron ores, for
example COREX.RTM. or FINEX.RTM., the reduction gas required is
provided from what is known as generator gas produced in a melter
gasifier by gasifying carbon carriers in the presence of oxygen and
pre-reduced iron carriers. The generator gas is excessively
dust-laden for use as reduction gas in a reduction reactor, and is
at a temperature which lies above a temperature range that is
favorable for the use thereof for reducing iron ore. The
temperature of the generator gas is not constant, but instead
fluctuates on account of pressure shocks in the melter gasifier in
a range of up to .+-.50.degree. C. about an average value of
approximately 1030.degree. C. to 1070.degree. C. So that it can be
used as reduction gas in a reduction reactor, the generator gas
therefore has to be dedusted and cooled. Within the context of this
application, generator gas is designated as reduction gas only once
dedusting and cooling have been effected. Here, cooling does not
concomitantly encompass a reduction in temperature which arises in
the form of heat loss upon passage through conduits.
[0004] It is known, for example from WO9801587, to free the
generator gas of entrained dust by means of dry dedusting in a
cyclone. The generator gas is cooled in that a partial quantity of
the reduction gas emerging from the cyclone is wet dedusted and
cooled in a washer and, following subsequent compression, is
supplied to the generator gas as so-called cooling gas before the
dry dedusting. A dedusted and cooled so-called reduction gas thus
emerges from the cyclone.
[0005] The cooling by means of the cooling gas circuit disclosed in
WO9801587 has the disadvantage that it is very complex in terms of
outlay on apparatus and required space. The plant parts required
for realizing the cooling gas circuit, such as washers and
compressors, shut-off valves and control valves, shut-off flaps and
control flaps, noise protection and buildings including cranes,
have to be provided, operated with a high energy consumption and
maintained--the compressors in particular cause considerable
maintenance costs in this case. In addition, the washers make a
considerable contribution to the required design size of the
wastewater system of a pig iron production plant as per WO9801587.
The energy removed from the reduction gas by the washers in a
cooling gas circuit is carried away unexploited with the washing
water, and further discharged to the surroundings via cooling
towers.
SUMMARY
[0006] In one embodiment, a method for providing reduction gas for
iron ore reduction by cooling and dry dedusting generator gas
produced in a melter gasifier for pig iron production,
characterized in that the generator gas is cooled both by water
injection and by heat exchange after it has been discharged from
the melter gasifier and before the dry dedusting thereof.
[0007] In a further embodiment, the heat exchange is effected with
at least one liquid heat exchange medium. In a further embodiment,
the liquid heat exchange medium is water. In a further embodiment,
the liquid heat exchange medium is thermal oil. In a further
embodiment, the water injection is effected before and/or during
the heat exchange. In a further embodiment, the inlet temperature
of the liquid heat exchange medium lies within a temperature range
with a minimum temperature of 70.degree. C., preferably 100.degree.
C., and with a maximum temperature which is lower than the lowest
temperature at which metal dusting corrosion occurs by reaction
with generator gas on the material of the device for heat exchange,
preferably lower than 450.degree. C., particularly preferably
150.degree. C.
[0008] In a further embodiment, the water injection is regulated in
accordance with the temperature of the generator gas after the heat
exchange. In a further embodiment, the water injection is regulated
in accordance with the temperature of the reduction gas produced by
the dry dedusting. In a further embodiment, the quantity of heat
withdrawn from the generator gas per unit of time during the heat
exchange is regulated by changing the temperature of the heat
exchange medium and/or the quantity of heat exchange medium
supplied per unit of time.
[0009] In another embodiment, a device for carrying out any of the
methods disclosed above is provided, comprising a reduction reactor
for reducing iron ore by means of a reduction gas, and a melter
gasifier for producing generator gas by gasifying carbon carriers
in the presence of oxygen and pre-reduced iron carriers, wherein
the melter gasifier and the reduction reactor are connected by a
gas line, in which a dry dedusting device is present, characterized
in that both a device for water injection and a device for heat
exchange are present in the gas line between the melter gasifier
and the dry dedusting device.
[0010] In a further embodiment, the device for heat exchange is
provided with a feed line for liquid heat exchange medium,
preferably water or thermal oil. In a further embodiment, the
device for water injection is arranged between the melter gasifier
and the end--as seen in the direction of flow of the generator
gas--of the device for heat exchange, preferably in the device for
heat exchange. In a further embodiment, the device for heat
exchange is in the form of a cooling jacket heat exchanger. In a
further embodiment, the cooling jacket heat exchanger has a cooling
jacket with a helical guide for heat exchange medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Example embodiments will be explained in more detail below
with reference to figures, in which:
[0012] FIG. 1 shows a conventional device for iron ore reduction by
means of a reduction gas obtained from a melter gasifier.
[0013] FIG. 2 shows an example device according to one embodiment
of the present disclosure.
[0014] FIG. 3 is a schematic illustration of a section through a
gas line portion which conducts generator gas and is provided with
a cooling jacket heat exchanger, according to one embodiment.
DETAILED DESCRIPTION
[0015] Some embodiments provide methods and devices in which a
generator gas is reliably cooled without a cooling gas circuit
according to conventional techniques, which may avoid certain
disadvantages of certain conventional techniques.
[0016] Some embodiments provide a method for providing reduction
gas for iron ore reduction by cooling and dry dedusting generator
gas produced in a melter gasifier for pig iron production, wherein
the generator gas is cooled both by water injection and by heat
exchange after it has been discharged from the melter gasifier and
before the dry dedusting thereof.
[0017] The terms melter gasifier, generator gas and reduction gas
are to be understood as defined above in the introduction. As is
generally known, pre-reduced iron carriers are additionally
completely reduced in the melter gasifier for producing generator
gas, and the pig iron which forms is melted down. In order to
provide a reduction gas, the generator gas, which--in addition to
carbon dioxide CO.sub.2, steam H.sub.2O and nitrogen
N.sub.2--consists primarily of reducing components such as carbon
monoxide CO, hydrogen H.sub.2 and methane CH.sub.4, is subjected to
dry dedusting and cooling, as in conventional techniques.
[0018] In some embodiments, the generator gas is cooled here both
by water injection and by heat exchange after it has been
discharged from the melt reduction unit and before the dry
dedusting thereof. Since the cooling is no longer effected by
introducing cooling gas produced from a partial quantity of the
reduction gas, the complex cooling gas circuit used in certain
conventional techniques may be dispensed with. The cooling is
effected already before the dry dedusting, in order to cool the
particles of the dust and to keep the thermal loading of the device
for dry dedusting as low as possible.
[0019] The combination of water injection and heat exchange may
make it possible to ensure that the generator gas is cooled setting
a degree of oxidation of the reduction gas which is favorable for
the following iron ore reduction and setting a constant temperature
of the reduction gas. The term constant temperature here is to be
seen in connection with industrial iron ore reduction plants and
the operation thereof, and therefore does not exclude small control
deviations from a desired temperature value.
[0020] Cooling by water injection alone would provide a reduction
gas, by water evaporation and the reaction of steam with carbon
monoxide, which would have a considerably higher degree of
oxidation compared to the procedure according to the present
disclosure--this is because the abandonment of cooling by heat
exchange would mean that significantly more water would have to be
injected to achieve a specific desired temperature for the
reduction gas, which is why the degree of oxidation of the
generator gas would be increased to a greater extent as a
result.
[0021] Here, the degree of oxidation is defined by the relationship
(CO.sub.2+H.sub.2O)/(CO+CO.sub.2+H.sub.2+H.sub.2O).
[0022] On account of the inertia of a heat exchanger system when it
reacts to temperature fluctuations of a gas stream to be cooled,
there is the problem that the reduction gas temperature would
likewise fluctuate given a greatly fluctuating generator gas
temperature. Reliable cooling at a maximum temperature by heat
exchange alone would make it necessary to design the plant parts
required for the maximum temperature peaks and volume throughputs
of the generator gas which occur. This in turn would create the
problem of reliably avoiding excessive cooling of the generator gas
at temperatures of the generator gas which lie below the
temperature peaks.
[0023] The combination of water injection and heat exchange for
cooling the generator gas may avoid or reduce disadvantages of the
two individual cooling concepts. The inert reacting cooling by heat
exchange is supplemented by the rapidly reacting water injection,
and the negative influence of the water injection on the degree of
oxidation of the reduction gas is reduced by the fact that not all
of the cooling is effected by water injection, but instead heat
exchange also removes some of the heat which is to be dissipated
during the cooling.
[0024] According to one embodiment of the method, the heat exchange
is effected with at least one liquid heat exchange medium. A liquid
heat exchange medium is used so that it is possible to reliably
keep the surface temperature of the heat exchanger below
450.degree. C. Cooling by gas or vapor, by contrast, has the
disadvantage that the heat transfer coefficient would be lower, and
therefore there would be an increased risk of higher surface
temperatures of the heat exchanger. A surface temperature of the
heat exchanger below 450.degree. C. may be preferred, in order to
avoid the risk of metal dusting corrosion of the heat exchanger by
reaction with components of the generator gas.
[0025] The liquid heat exchange medium is, for example, water,
which may be pressurized and may also have been specially
treated--for example demineralized or desalinated water--, or
thermal oil, produced for example from synthetic oils or organic
oils.
[0026] In steel, petrochemical and 0RC plants, use is made, for
example, of the commercially available thermal oil THERMINOL.RTM.
66 for heat displacement or waste heat recovery.
[0027] An advantage of thermal oil over water is the significantly
higher boiling point, which can lie at temperatures above
300.degree. C. Furthermore, the use of thermal oil is easier to
manage in terms of apparatus, since it is generally used at
atmospheric pressure and therefore, in contrast to water-carrying
plants, the plants do not have to be designed for an excess
pressure. Specifically, water is often used at an excess pressure,
and therefore the plants have to be designed to be more stable. It
is of course possible in some embodiments for thermal oil to also
be used at excess pressure, however.
[0028] A disadvantage compared to water is the need to couple the
heat obtained via thermal oil into another product medium if the
heat is to be utilized. Furthermore, thermal oil generally has a
smaller heat capacity than water, and the heat of evaporation
cannot be utilized in the case of saturated steam operation.
[0029] The water injection can be effected before, during or after
the heat exchange. It may be advantageous for the water injection
to be effected before and/or during the heat exchange. In this way,
it may be possible to provide a sufficient evaporation distance for
injected water and to achieve temperature equalization of the
generator gas stream more easily before the dry dedusting.
[0030] Particularly if the water injection is effected before
and/or during the heat exchange, it may be advantageous if the
inlet temperature of the liquid heat exchange medium lies within a
temperature range with a minimum temperature of 70.degree. C.,
e.g., 100.degree. C., and with a maximum temperature which is lower
than the lowest temperature at which metal dusting corrosion occurs
by reaction with generator gas on the material of the device for
heat exchange, e.g., lower than 450.degree. C., e.g., 150.degree.
C. It may be preferable for the inlet temperature to lie within a
temperature range of 100.degree. C. to 150.degree. C.
[0031] This is because, if water injection is effected before
and/or during the heat exchange, the steam content of the generator
gas rises, and therefore the surfaces of the device for heat
exchange should be at temperatures which make it possible to
reliably avoid condensation of steam. Such a condensation entails
the risk of the formation of undesirable caking of dust entrained
in the generator gas. At a minimum temperature of 70.degree. C.,
e.g., 100.degree. C., the risk of condensation is largely
averted.
[0032] The maximum temperature should be lower than the lowest
temperature at which metal dusting corrosion occurs by reaction
with generator gas on the material of the device for heat exchange,
e.g., lower than 450.degree. C., in order to avoid the risk of
metal dusting corrosion, which typically occurs in the range of
approximately 450.degree. C.-900.degree. C. in the case of common
materials for devices for heat exchange, as a result of excessively
high surface temperatures in the device for heat exchange.
[0033] It may be preferable for the water injection to be regulated
in accordance with the temperature of the generator gas after the
heat exchange. It may be advantageous for the water injection to be
regulated in accordance with the temperature of the reduction gas
produced by the dry dedusting. In this way, it may be possible to
promptly react to changes in the temperature of the reduction
gas.
[0034] In any event, the temperature used for regulating the water
injection should be a temperature of the generator gas--or of the
reduction gas--after water injection has been effected.
[0035] According to one embodiment, this regulation is effected
with the inclusion of information relating to the cooling power
which can be provided by heat exchange--in addition to the cooling
power by water injection. If it is foreseeable, for example, that
the cooling being effected given an adjustment A of the water
injection leads to a temperature of the generator gas subjected to
the heat exchange which cannot be cooled down to a desired
temperature for the reduction gas by the heat exchange, the
adjustment of the water injection is regulated to an adjustment B,
which makes it possible to set the desired temperature with the
cooling power of the heat exchange.
[0036] According to one embodiment of the method, the quantity of
heat withdrawn from the generator gas per unit of time during the
heat exchange, i.e., the cooling power, is regulated by changing
the temperature of the heat exchange medium and/or the quantity of
heat exchange medium supplied per unit of time. This regulation,
too, can be effected in accordance with the temperature of the
reduction gas produced by the dry dedusting. It is also possible to
use the temperature of the generator gas downstream of the heat
exchanger before the dry dedusting for regulation. In any event,
the temperature used for regulation should be a temperature of the
generator gas--or of the reduction gas--after heat exchange has
been effected.
[0037] According to one embodiment, a specific basic quantity of
heat energy is withdrawn from the generator gas by means of heat
exchange, and quantities of heat additionally to be withdrawn are
withdrawn by water injection. On account of the fluctuations in the
generator gas temperature, these additional quantities of heat vary
over time. The water injection allows for easier and quicker
adaptation of the cooling power to the fluctuations in the
generator gas temperature than regulation of the cooling power by
way of the heat exchange.
[0038] As opposed to a conventional cooling gas circuit, a further
advantage of the techniques disclosed herein is that the water
injection contributes, by a gasification reaction of coal dust
entrained in the generator gas with the injected water, to the
formation of reducing compounds such as CO and H.sub.2, in
accordance with the heterogeneous reaction
C+H.sub.2O.fwdarw.CO+H.sub.2.
[0039] Correspondingly converted coal dust from the generator gas
then does not have to be separated during the dry dedusting--which
relieves the burden on the dry dedusting device--and contributes to
the reduction capacity of the reduction gas.
[0040] Some embodiments provide a device for carrying out any of
the methods disclosed herein. Thus, such device may comprise a
reduction reactor for reducing iron ore by means of a reduction
gas, and a melter gasifier for producing generator gas by gasifying
carbon carriers in the presence of oxygen and pre-reduced iron
carriers, wherein the melter gasifier and the reduction reactor are
connected by a gas line, in which a dry dedusting device is
present, characterized in that both a device for water injection
and a device for heat exchange are present in the gas line between
the melter gasifier and the dry dedusting device.
[0041] The reduction reactor for reducing iron ore can be a fixed
bed reactor or a fluidized bed reactor, for example. A plurality of
such reduction reactors can also be present in series or connected
in parallel. In the reduction reactor, iron ore is at least
partially reduced by means of a reduction gas. In a melter
gasifier, as is known for example from COREX.RTM. or FINEX.RTM.,
generator gas is produced. The melter gasifier and the reduction
reactor are connected by a gas line. A dry dedusting device, for
example a cyclone or a ceramic hot gas filter, is present in said
gas line and dedusts the generator gas fed into the gas line from
the melter gasifier.
[0042] Both a device for water injection and a device for heat
exchange are present in the gas line between the melter gasifier
and the dry dedusting device.
[0043] The generator gas fed into the gas line from the melter
gasifier flows in the direction of the reduction reactor. In this
case, it passes through both the device for water injection and the
device for heat exchange, by means of which it is cooled, and the
dry dedusting device, by means of which the dust load thereof is
reduced. The gas emerging from the dry dedusting device, which gas
is cooled to a temperature favorable for carrying out the reduction
in the reduction reactor and dedusted, is designated within the
context of this application as reduction gas. The reduction gas is
supplied to the reduction reactor via the gas line.
[0044] The device for water injection may comprise, for example,
one to three water nozzles per generator gas line. The water
nozzles may be two-fluid nozzles which atomize water with nitrogen
or steam or process gas as atomization gas. As a result, the
droplet size is minimized, which ensures a short evaporation
distance for evaporation of the injected water in the generator gas
stream, and a sufficient mixing distance for mixing the injected
water in the generator gas stream. Evaporation within a short
distance and mixing in this case help to exploit the cooling action
of the injected water.
[0045] A device for heat exchange is to be understood to mean one
or a plurality of indirect heat exchangers per generator gas line.
A typical COREX.RTM. or FINEX.RTM. plant has 4 generator gas lines.
The heat exchangers can be operated as water preheaters or as water
evaporators. Operation as superheaters would generally be
disadvantageous, because in this case a poor transfer of heat from
the heat exchanger to vapor, the heat exchange medium, would make
metal dusting corrosion possible on account of high surface
temperatures of the heat exchanger which are consequently present.
If the material of the heat exchangers is resistant to metal
dusting corrosion under the conditions of operation as
superheaters, however, it is also possible for the heat exchangers
to be operated as superheaters or as gas-gas heat exchangers.
[0046] The device for heat exchange may have a plurality of heat
exchangers which, with respect to feed lines and discharge lines
for heat exchange medium, are connected in parallel or in series.
This may provide advantages in production and assembly, and has the
effect that instances of thermal expansion in the installed state
present fewer problems--here, the advantages are applicable if use
is made, instead of a large heat exchanger with a specific surface
area for heat exchange, of a plurality of smaller heat exchangers
whose surface areas for heat exchange correspond in total to that
of the large heat exchanger.
[0047] According to one embodiment, the device for heat exchange is
in the form of a cooling jacket heat exchanger. In this case, it
may have a smooth surface on the inner side and has no fittings on
the inner side. This serves for largely avoiding problems such as
caking and abrasion resulting from dust.
[0048] It may be advantageous for the cooling jacket heat exchanger
to have a cooling jacket with a helical guide for heat exchange
medium. This may allow for particularly efficient cooling.
[0049] The device for heat exchange can be arranged, for example,
within a pipeline for conducting generator gas. However, it can
also itself form said pipeline. Pipelines for conducting generator
gas generally comprise a layer of anti-wear masonry, facing toward
the generator gas, for protection against wear resulting from the
hot generator gas and the dust load thereof, said layer of
anti-wear masonry being surrounded toward the outside by a layer of
insulating masonry for thermal insulation. If the device for heat
exchange is arranged within a pipeline for conducting generator
gas, it is fitted at the site of the anti-wear masonry. It may be
fitted movably within the insulating masonry; by way of example, a
spacing can be left free between the device for heat exchange and
the insulating masonry and is sealed off against penetration by
gases by means of a seal, for example silicone-sheathed ceramic
sealing beads.
[0050] The feed lines and discharge lines for heat exchange medium
may be provided with compensators in order to avoid stresses and
instances of material fracture, caused by instances of thermal
expansion, in the region of the inlet or of the outlet of the feed
lines and discharge lines into that part of the device for heat
exchange which provides the surface area for heat exchange.
[0051] According to some embodiments, the device for heat exchange
can be operated as a preheater for heat exchange medium and/or as
an evaporator for heat exchange medium.
[0052] According to one embodiment, the device for heat exchange is
provided with a feed line for liquid heat exchange medium, e.g.,
water or thermal oil.
[0053] The device for water injection can be arranged between the
melter gasifier and the device for heat exchange, in the device for
heat exchange or between the device for heat exchange and the dry
dedusting device.
[0054] According to one embodiment, the device for water injection
is arranged between the melter gasifier and the end--as seen in the
direction of flow of the generator gas--of the device for heat
exchange. According to one embodiment, the device for water
injection is arranged in the device for heat exchange. It may be
preferable for the device for water injection to be arranged
between the melter gasifier and the start--as seen in the direction
of flow of the generator gas--of the device for heat exchange.
[0055] The actually selected site at which the device for water
injection is arranged depends, for example, on where in a given
device for carrying out a method as disclosed herein optimum
turbulence of the injected water can be achieved. The vapor which
may be produced in the device for heat exchange can be used, for
example, in a COREX.RTM. or FINEX.RTM. process for the substitution
of smelter vapor for trace heating, or for vapor injection systems
for oxygen nozzles. The exploitation of the energy withdrawn from
the generator gas by heat exchange makes it possible for the method
for iron ore reduction or for producing pig iron to be carried out
more economically overall.
[0056] FIG. 1 shows a device for carrying out a method for
providing reduction gas for iron ore melt reduction by cooling and
dry dedusting generator gas produced in a melter gasifier for pig
iron production according to a conventional system, in accordance
with the COREX.RTM. method.
[0057] Iron ore 2 is introduced into a reduction reactor 1, in this
case a fixed bed reactor, and reduced by a reduction gas. Carbon
carriers 4, pre-reduced iron carriers 5 obtained in the reduction
reactor during the reduction of the iron ore and oxygen 6 are
introduced into a melter gasifier 3. The pig iron obtained from the
pre-reduced iron carriers 5 in the melter gasifier 3 as a result of
the complete reduction thereof is melted down, and can be removed
from the melter gasifier 3. The generator gas formed in the melter
gasifier 3 by gasification reactions of the carbon carriers 4 with
the oxygen 6 in the presence of the pre-reduced iron carriers 5 is
discharged from the melter gasifier 3 through the gas line which
connects the melter gasifier 3 to the reduction reactor 1. The gas
line portion 7a of the gas line conducts generator gas. The dust
load of the generator gas is reduced in a dry dedusting device 8,
here a cyclone, present in the gas line. Dust separated in the
cyclone is returned into the melter gasifier 3. A partial quantity
of the reduction gas emerging from the dry dedusting device 8 is
subjected to wet washing in a washer 9 and in the process is
largely freed of remaining dust and cooled. A partial quantity of
the gas taken from the washer 9 is fed to the generator gas, after
compression, before it enters the dry dedusting device 8. This
reduces the temperature of the generator gas entering the dry
dedusting device 8, i.e. the generator gas is cooled. Accordingly,
reduction gas emerges from the dry dedusting device 8, in
accordance with the definition of the present application.
Accordingly, generator gas is conducted in the gas line portion 7a,
and reduction gas is conducted in the gas line portion 7b. The gas
line comprises the two gas line portions 7a and 7b. After washing
in the washer 10, top gas emerging from the reduction reactor 1 is
supplied, together with a partial quantity of the reduction gas
treated in the washer 9, as export gas 11 to further consumers, for
example power plants or pelletizing systems, as an energy
provider.
[0058] The device parts which are utilized for the wet washing, for
compression and for feeding wet-washed, compressed reduction gas
into the generator gas are referred to as the cooling gas
circuit.
[0059] FIG. 2 shows an example device according to one embodiment
which is comparable to FIG. 1. Comparable parts of the device are
provided with the same reference signs as in FIG. 1. In contrast to
the conventional device shown in FIG. 1, there is no cooling gas
circuit with a washer 9 and a compressor. For cooling the generator
gas, both a device for water injection 12 and a device for heat
exchange 13 are present in the gas line instead between the melter
gasifier and the dry dedusting device 8, here a cyclone.
[0060] The device for heat exchange 13 is provided with a feed line
for liquid heat exchange medium 14, in this case pressurized water.
The device for heat exchange 13 is in the form of a cooling jacket
heat exchanger, with the cooling jacket heat exchanger having a
helical guide for the heat exchange medium--the pressurized
water.
[0061] The device for water injection 12 is arranged between the
melter gasifier and the device for heat exchange 13. The water
injection is regulated in accordance with the temperature of the
reduction gas produced by the dry dedusting. To this end, a valve
15 and a temperature sensor 16 are connected to one another on the
gas line portion 7b via a regulating device 17.
[0062] FIG. 3 is a schematic illustration of a section through part
of the gas line portion 7a, which is connected to a cooling jacket
heat exchanger 18 as the device for heat exchange 13. The cooling
jacket heat exchanger 18 is provided with a helical guide for the
heat exchange medium, which is indicated by dashed lines within the
cooling jacket heat exchanger 18. The cooling jacket heat exchanger
is arranged within the pipeline for conducting generator gas 19 of
the gas line portion 7a. In the portions without a cooling jacket
heat exchanger, the pipeline for conducting generator gas 19 has a
layer of anti-wear masonry 21, facing toward the generator gas 20,
which is illustrated by wavy arrows in the direction of flow, for
protection against wear resulting from the hot generator gas and
the dust load thereof, said layer of anti-wear masonry being
surrounded toward the outside by a layer of insulating masonry 22
for thermal insulation. Where the cooling jacket heat exchanger 18
is arranged within the pipeline for conducting generator gas 19, it
is fitted at the site of the anti-wear masonry 21. An intermediate
space 23 between the cooling jacket heat exchanger 18 and the
insulating masonry 22 is left free, as a result of which the
cooling jacket heat exchanger 18 is fitted movably within the
insulating masonry 22. For reasons of clarity, seals which are
present for the intermediate space 23 against the penetration of
gases have not been illustrated.
[0063] The feed line 24 and discharge line 25 for heat exchange
medium, in this case water--shown by dashed arrows--, are provided
with compensators (not shown) in order to avoid stresses and
instances of material fracture, caused by instances of thermal
expansion, in the region of the inlet or of the outlet of the feed
lines and discharge lines into that part of the cooling jacket heat
exchanger 18 which provides the surface area for heat exchange.
LIST OF ELEMENTS SHOWN IN THE DRAWINGS
[0064] 1 Reduction reactor [0065] 2 Iron ore [0066] 3 Melter
gasifier [0067] 4 Carbon carriers [0068] 5 Iron carriers [0069] 6
Oxygen [0070] 7a Gas line portion [0071] 7b Gas line portion [0072]
8 Dry dedusting device [0073] 9 Washer [0074] 10 Washer [0075] 11
Export gas [0076] 12 Device for water injection [0077] 13 Device
for heat exchange [0078] 14
[0079] Liquid heat exchange medium [0080] 15 Valve [0081] 16
Temperature sensor [0082] 17 Regulating device [0083] 18 Cooling
jacket heat exchanger [0084] 19 Pipeline for conducting generator
gas [0085] 20 Generator gas [0086] 21 Anti-wear masonry [0087] 22
Insulating masonry [0088] 23 Intermediate space [0089] 24 Feed line
[0090] 25 Discharge line
* * * * *