U.S. patent application number 15/635892 was filed with the patent office on 2017-10-19 for method for producing steel.
The applicant listed for this patent is voestalpine Stahl GmbH. Invention is credited to Thomas Burgler, Wolfgang Eder, Peter Schwab.
Application Number | 20170298461 15/635892 |
Document ID | / |
Family ID | 60040013 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170298461 |
Kind Code |
A1 |
Eder; Wolfgang ; et
al. |
October 19, 2017 |
METHOD FOR PRODUCING STEEL
Abstract
A method for producing steel in which iron ore is reduced with
hydrogen and the resulting intermediate product of reduced iron ore
is subjected to further metallurgical processing; the hydrogen is
produced through electrolysis of water; the electrical energy
required for the electrolysis is regenerative energy from
hydroelectric, wind, and/or photovoltaic sources and the hydrogen
and/or the intermediate product is produced regardless of demand,
whenever enough regeneratively produced electrical energy is
available; and unneeded intermediate product is stored until there
is demand or it is used so that the regenerative energy that is
stored therein is also stored; and using a calculation model to
calculate a required discharge rate in a reduction shaft to achieve
a desired metallization grade of the steel by tracing batches of
the iron ore in the reduction shaft, and using the calculation
model to calculate the amount of carbon-containing gas or
hydrogen-containing gas to add to the hydrogen for the
reduction.
Inventors: |
Eder; Wolfgang; (Linz,
AT) ; Burgler; Thomas; (Steyregg, AT) ;
Schwab; Peter; (Linz, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
voestalpine Stahl GmbH |
Linz |
|
AT |
|
|
Family ID: |
60040013 |
Appl. No.: |
15/635892 |
Filed: |
June 28, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14428206 |
Mar 13, 2015 |
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PCT/EP2013/068726 |
Sep 10, 2013 |
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15635892 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02E 60/36 20130101;
C21B 13/0073 20130101; Y02E 60/366 20130101; Y02E 70/10 20130101;
C25B 1/04 20130101 |
International
Class: |
C21B 13/00 20060101
C21B013/00; C25B 1/04 20060101 C25B001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 2012 |
DE |
102012108631.1 |
Sep 28, 2012 |
DE |
102012109284.2 |
Apr 19, 2013 |
DE |
102013104002.0 |
Claims
1. A method for producing steel, comprising: reducing iron ore with
hydrogen and subjecting a resulting intermediate product of reduced
iron ore to further metallurgical processing, wherein the hydrogen
is produced through electrolysis of water, and electrical energy
required for the electrolysis is regenerative energy selected from
the group consisting of hydroelectric sources, wind sources, and
photovoltaic sources; and the hydrogen and/or the intermediate
product is produced regardless of demand for energy, whenever
enough regeneratively produced electrical energy is available,
where unneeded intermediate product is stored until there is demand
or it is used so that the regenerative energy that is stored
therein is also stored, and in reducing the iron ore to produce the
intermediate product, a carbon-containing or hydrogen-containing
gas is added to the hydrogen in order to incorporate carbon into
the intermediate product; and the hydrogen for the reduction has at
least enough carbon-containing gas or hydrogen-containing gas added
to it to make a carbon content in the intermediate product 0.0005
mass % to 6.3 mass %; using a calculation model to calculate a
required discharge rate in a reduction shaft to achieve a desired
metallization grade of the steel by tracing batches of the iron ore
in the reduction shaft; and using the calculation model to
calculate the amount of carbon-containing gas or
hydrogen-containing gas to add to the hydrogen for the reduction;
wherein the calculation model is
Fe.sub.2O.sub.3+6CO.fwdarw.2Fe+3CO+3CO.sub.2 for carbon-containing
gas flows and
Fe.sub.2O.sub.3+6H.sub.2.fwdarw.2Fe+3H.sub.2+3H.sub.2O for
hydrogen-containing gas flows.
2. The method according to claim 1, wherein the carbon-containing
or hydrogen-containing gas is obtained from a source selected from
the group consisting of industrial processes, biogas production,
pyrolysis, and synthesis gas from biomass.
3. The method according to claim 1, wherein the hydrogen for the
reduction has at least enough carbon-containing-or
hydrogen-containing gas added to it to make the carbon content in
the intermediate product 1 mass % to 3 mass %.
4. The method according to claim 1, wherein the reduction gas
composed of hydrogen and possibly a carbon-containing gas is
introduced into the reduction process at a temperature of
450.degree. C. to 1200.degree. C.
5. The method according to claim 1, wherein excess pressure in the
reduction is between 0 bar and 15 bar.
6. The method according to claim 1, wherein a ratio between
hydrogen from regenerative production and carbon-containing or
hydrogen-containing gas flows is varied continuously as a function
of availability; when there is sufficient regenerative energy,
hydrogen from the production with regenerative energy is used and
in the absence of regenerative energy, then the system switches to
purely carbon-containing or hydrogen-containing gas flows.
7. The method according to claim 1, wherein an adjustment of the
content of hydrogen and, or carbon-containing or
hydrogen-containing vas flows in the overall gas flow is carried
out using a predictive control; the predictive control is used to
measure at least one of the group consisting of a predicted
yield/production quantity of hydrogen, regenerative energy,
carbon-containing or hydrogen-containing gas flows from biogas
production or from pyrolysis of renewable resources, and forecasts
flow into an estimation of regenerative energy; and demand
predictions of other external consumers also flow into the process,
thus permitting the electrical energy from regenerative sources to
be distributed optimally and in a most economical fashion.
8. The method according to claim 1, wherein gas flow that is
emitted as exhaust by a direct reduction system is conveyed into
the process as a carbon-containing or hydrogen-containing gas flow.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method for producing steel in
which iron ore is reduced with hydrogen and the resulting
intermediate product of reduced iron ore and possibly accompanying
substances is subjected to further metallurgical processing, and a
method for storing discontinuously produced energy.
BACKGROUND OF THE INVENTION
[0002] Steel production is currently carried out in a variety of
ways. Classic steel production is carried out by producing pig iron
in the hot furnace process, primarily out of iron oxide carriers.
In this method, approx. 450 to 600 kg of reducing agent, usually
coke, is consumed per metric ton of pig iron; this method, both in
the production of coke from coal and in the production of the pig
iron, releases very significant quantities of CO.sub.2. In
addition, so-called "direct reduction methods" are known (methods
according to the brands MIDREX, FINMET, ENERGIRON/HYL, etc.), in
which the sponge iron is produced primarily from iron oxide
carriers in the form of HDRI (hot direct reduced iron), CDRI (cold
direct reduced iron), or so-called HBI (hot briquetted iron).
[0003] There are also so-called smelting reduction methods in which
the melting process, the production of reduction gas, and the
direct reduction are combined with one another, for example the
methods of the brands COREX, FINEX, HiSmelt, or HiSarna.
[0004] Sponge irons in the form of HDRI, CDRI, and HBI usually
undergo further processing in electric furnaces, which is
extraordinarily energy-intensive. The direct reduction is carried
out using hydrogen and carbon monoxide from methane, and synthesis
gas if necessary. For example, in the so-called MIDREX method,
first methane is transformed according to the following
reaction:
CH.sub.4+CO.sub.2=2CO+2H.sub.2
[0005] and the iron oxide reacts with the reduction gas, for
example according to the following formula:
Fe.sub.2O.sub.3+6CO(H.sub.2)=2Fe+3CO.sub.2 (H.sub.2O)+3
CO(H.sub.2).
[0006] This method also emits CO.sub.2.
[0007] DE 198 53 747 C1 has disclosed a combined process for the
direct reduction of fine ores in which the reduction is to be
carried out with hydrogen or another reduction gas in a horizontal
turbulence layer.
[0008] DE 197 14 512 A1 has disclosed a power station with solar
power generation, an electrolysis unit, and an industrial
metallurgical process; this industrial process relates either to
the power-intensive metal production of aluminum from bauxite or is
intended to be a metallurgical process with hydrogen as a reducing
agent in the production of nonferrous metals such as, tungsten,
molybdenum, nickel, or the like or is intended to be, a
metallurgical process with hydrogen as a reducing agent using the
direct reduction method in the production of ferrous metals. The
cited document, however, does not explain this in detail.
[0009] WO 2011/018124 has disclosed methods and systems for
producing storable and transportable carbon-based energy sources
using carbon dioxide and using regenerative electrical energy and
fossil fuels. In this case, a percentage of regeneratively produced
methanol is prepared together with a percentage of methanol that is
produced by means of non-regenerative electrical energy and/or by
means of direct reduction and/or by means of partial oxidation
and/or reforming.
[0010] In all of the steel production methods known up to this
point, it is disadvantageous that there is a lack of a sustainable,
comprehensive production concept based on regenerative resources
for steel production on an industrial scale.
[0011] The object of the invention is to create a method with which
pig iron and in particular steel can be produced on an industrial
scale in a CO2-neutral fashion.
SUMMARY OF THE INVENTION
[0012] According to the invention, the steel production is carried
out at least partially, preferably completely, with regenerative
energy; in this case, on the one hand, a direct reduction method is
used and on the other hand, the intermediate product obtained in
the direct reduction method is correspondingly processed further,
for example in an electric arc furnace. However, a use in the LD
process and/or in a blast furnace would also be possible. A
particular advantage is that the intermediate product produced by
means of regenerative energy can be stored until it is processed
further, which means that the method according to the invention
permits a storage of regenerative energy. Up to now, this very
storage of regenerative energy has presented a very large problem
since in particular, electrical energy that is generated from wind
or sun depends on climatic conditions that are not always the same.
Even hydroelectrically generated electrical energy is not always
available. Often, the consumers are not in the same locations as
the production of regenerative energy. This problem of storage and
of transporting stored energy is solved by means of the invention
since the intermediate product produced according to the invention
can be efficiently transported in small units and in any quantity
to any location, for example by marine transport.
[0013] In the method according to the invention, this electrical
energy generated from wind, hydro, or solar energy is used to
produce hydrogen from water by electrolysis. Preferably at the site
of the production of the hydrogen, a direct reduction system is
operated, which is used for reducing iron ores--which are likewise
preferably prepared with electrical energy produced in this way.
The intermediate product obtained in this way is an ideal way to
store this regenerative energy, can be stored until it is used, and
is accessible via any form of transportation to a system for
processing it further, particularly when it is needed there. In
particular, this intermediate product can be produced at its
production site--in large quantities that exceed the present
requirement--when the corresponding electrical energy is available
in sufficient quantity. If this energy is not available, then there
are sufficient quantities of the intermediate product and thus also
of the energy in order to be able to meet the need.
[0014] Operating a corresponding electrical arc, likewise
particularly preferably using only energy produced from wind-,
hydroelectric-, or solar energy, succeeds in achieving a
CO.sub.2-free steel production and also in storing regenerative
energy. Alternatively, the intermediate product can also be used
with a blast furnace or the LD process.
[0015] According to the invention, the hydrogen from the
regenerative processes can be used with carbon-containing or
hydrogen-containing gas flows such as CH4, COG, synthesis gas etc.,
in a direct reduction system. The ratio of hydrogen from the
regenerative processes to carbon-containing or hydrogen-containing
gas flows can be continuously varied as a function of availability.
For example, if a very large amount of hydrogen is available, this
can be used up to almost 100% for the direct reduction. The rest is
made up of the minimally required carbon-containing or
hydrogen-containing gas flow for adjusting the percentage of
carbon, if necessary, however, it is also possible to switch to
purely carbon-containing or hydrogen-containing gas flows (for
example natural gas, biogas, gas from pyrolysis, renewable
resources).
[0016] Preferably, however, the method is carried out so that
regenerative energy, when present, is used to produce as much
hydrogen as the existing energy permits and this hydrogen is used
for the direct reduction. It goes without saying that
carbon-containing or hydrogen-containing gas flows also include gas
flows from biogas production and pyrolysis of renewable
resources.
[0017] Excess hydrogen that cannot be used immediately can be
temporarily stored.
[0018] This temporary storage of hydrogen can, for example, be
provided by a gas holder and the adjustment of the contents of
carbon-containing or hydrogen-containing gas flows can be carried
out by means of a predictive control. This predictive control can
measure the predicted yield/production quantity of hydrogen or
regenerative energy, but can also be used, for example, to estimate
the production quantity of regenerative energy based on weather
forecasts. Demand forecasts of other external consumers can also
flow into this predictive control so that the electrical energy
produced from regenerative sources is optimally used in the most
economical fashion.
[0019] The temperatures of the gas flow that prevail in this case
are adjusted by heating--for example with reformers, heaters, or
partial, oxidation--to 450.degree. C. to 1200.degree. C.,
preferably 600.degree. C. to 1200.degree. C., in particular
700.degree. C. to 900.degree. C. and then introduced into the
direct reduction method in order to perform a chemical reaction
there. In addition, the gas flow that exits the direct reduction
method can be fed back into the process as a carbon-containing or
hydrogen-containing gas flow.
[0020] The resulting possible intermediate products according to
the invention are HBI, HDRI, or CDRI.
[0021] In this case, excess pressures of 0 bar to 15 bar are
adjusted. For example, excess pressures of approx. 1.5 bar are
preferred in the MIDREX process and excess pressures of
approximately 9 bar are preferred in the Energiron process.
[0022] When regeneratively produced hydrogen is mixed with
carbon-containing or hydrogen-containing gas flows, the carbon
content can be adjusted in an ideal fashion and in fact can be
adjusted to 0.0005% to 6.3%, preferably 1% to 3%, and directly
incorporated into the intermediate product as C or Fe.sub.3C. An
intermediate product of this kind is ideally adjusted in terms of
the carbon content and is particularly well suited to further
processing since it contributes the carbon content that is required
for the metallurgical process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The invention will be explained by way of example in
conjunction with the drawings. In the drawings:
[0024] FIG. 1 shows an overview of the method according to the
invention in an exemplary embodiment (electric arc furnace);
[0025] FIG. 2 shows an overview of the method according to the
invention in a second exemplary embodiment (LD process);
[0026] FIG. 3 schematically depicts the flows of materials and
energy.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] According to the invention, a method for producing steel
includes reducing iron ore with hydrogen and subjecting a resulting
intermediate product of reduced iron ore to further metallurgical
processing. The hydrogen may be produced through electrolysis of
water. Electrical energy required for the electrolysis may be
regenerative energy, such as from hydroelectric sources, wind
sources, and/or photovoltaic sources.
[0028] According to certain embodiments, the reduction of the
primarily iron oxide carriers is carried out by means of hydrogen
and if necessary carbon carriers, either CO.sub.2 from industrial
processes with inevitable CO.sub.2 emissions or methane
particularly from regenerative processes such as biogas
production.
[0029] As is known, the iron reduction can occur in three possible
ways: [0030] "classic" blast furnace process--production of pig
iron from iron carriers and reducing agents, primarily coke [0031]
direct reduction--for example MIDREX--sponge iron (HDRI, CDRI, and
HBI), [0032] smelting reduction--combination of the smelting
process, reduction gas production, and direct reduction, for
example COREX OR FINEX,
[0033] Iron reduction (hematite, iron(III)) oxide is carried out by
means of:
carbon monoxide: Fe.sub.2O.sub.3+6CO.fwdarw.2Fe+3CO+3CO.sub.2
hydrogen: Fe.sub.2O.sub.3+6H2.fwdarw.2Fe+3H.sub.2+3H.sub.2O
[0034] In this case, the intermediate product obtained in the
direct reduction method can be so-called DRI (direct reduced iron)
or HBI (hot briquetted iron), which can be smelted into steel in
accordance with FIG. 1 in an electric arc furnace, possibly with
the addition of scrap.
[0035] FIG. 1 also shows that HDRI car CDRI can also be conveyed,
without the "detour" of HBI production, directly into the electric
furnace.
[0036] According to the invention, HBI can also be used in other
metallurgical processes in addition to the electric arc furnace
process, e.g. in the blast furnace process or as a scrap
replacement in the LD process.
[0037] Such an embodiment is shown in FIG. 2. In this case, it
should also be noted that CDRI and HDRI can also be conveyed,
directly into the blast furnace process or LD process.
[0038] The amount of available renewable energy varies during the
production of steel. In a preferred embodiment, in order to
compensate for temporary fluctuations in the production of
renewable energy, this energy can be stored in the form of hydrogen
if a surplus of it is available. This storage can occur, for
example, in a gas holder. Such a store can then be used in the
event of fluctuations. Temporary fluctuations can be predictable,
e.g. at night in solar installations, or unpredictable, e.g.
fluctuations in wind intensity in wind energy plants.
[0039] Longer-term fluctuations that can occur among other things
due to the different seasons can preferably be factored into the
energy storage in the form of HBI.
[0040] If necessary, it is also possible to draw on the use of
carbon-containing or hydrogen-containing gases such as natural gas
and a use of hydrogen can be optimally carried out only with
sufficiently renewable electrical power.
[0041] This advantageously yields the optimal potential uses of
regenerative energy since this energy can be used continuously as a
function of the availability of the corresponding form of energy
and the remaining energy that is lacking can be supplemented as
needed by means of other energy carriers. It is thus possible at
any time to reduce the emission of CO.sub.2 to the minimum possible
at this moment through the use of regenerative energy sources.
[0042] Another advantage of the invention lies in the spatial
decoupling of the locations of the production of regenerative
energy and the use of this energy. For example, solar power
stations can be constructed in warmer regions with favorable
amounts of solar radiation in which space is plentiful, whereas
steel mills are often found in the vicinity of rivers or seas.
[0043] Since the energy produced is stored in HBI, for example, it
can be transported easily and efficiently.
[0044] To compensate for fluctuations as explained above, the
hydrogen and/or the intermediate product may be produced regardless
of demand for energy, whenever enough regeneratively produced
electrical energy is available. Unneeded intermediate product is
stored until there is demand or it is used so that the regenerative
energy that is stored therein is also stored. In reducing the iron
ore to produce the intermediate product, a carbon-containing or
hydrogen-containing gas is added to the hydrogen in order to
incorporate carbon into the intermediate product. The hydrogen for
the reduction has at least enough carbon-containing gas or
hydrogen-containing gas added to it to make a carbon content in the
intermediate product 0.0005 mass % to 6.3 mass %.
[0045] Due to the fluctuations, it is beneficial to track the
material in a reduction shaft in batches. As used herein, the term
"batch" refers to an amount of material charged to the reduction
shaft in a given time period. For each of these batches, the
reduction level and the carbonization level have to be calculated
over time, taking into account that the reduction gas will change
due to non-availability of hydrogen from renewable sources. So each
batch will be confronted with a more hydrogen-containing gas flow,
if hydrogen is available from either renewable energy sources or
from an external buffer. Alternatively, the reduction gas will
contain more carbon if no hydrogen is available, and other sources,
like natural gas, have to be used. Since this influences
metallization and carbon-content of the product, as well as
cementation of the product, a solution is needed to achieve
consistent product quality over time.
[0046] A calculation model may be run during operation to calculate
the actual values for metallization and carbon-content for each
batch. More particularly, the calculation model may be used to
calculate a required discharge rate in a reduction shaft to achieve
a desired metallization grade of the steel by tracing batches of
the iron ore in the reduction shaft. The same calculation model may
be used to calculate the amount of carbon-containing gas or
hydrogen-containing gas to add to the hydrogen for the reduction.
The calculation model is:
Fe.sub.2O.sub.3+6CO.fwdarw.2Fe+3CO+3CO.sub.2 for carbon-containing
gas flows; and
Fe.sub.2O.sub.3+6H.sub.2.fwdarw.2Fe+3H.sub.2+3H.sub.2O for
hydrogen-containing gas flows.
[0047] To correct for the right carbon-content, carbon-containing
gas has to be added to the hydrogen gas flow or, vice versa,
hydrogen to the carbon-containing gas flow of, for example, natural
gas. It is important that these calculations are not performed for
the complete reduction shaft, but for each individual batch.
* * * * *