CN116888281A

CN116888281A - Intelligent hydrogen production for DRI manufacture

Info

Publication number: CN116888281A
Application number: CN202180093676.8A
Authority: CN
Inventors: C.卡斯塔尼奧拉; F.克拉维诺; S.伊拉夸; S.马格纳尼; J.克鲁尔
Original assignee: Paul Wurth SA
Current assignee: Paul Wurth SA
Priority date: 2020-12-18
Filing date: 2021-12-17
Publication date: 2023-10-13

Abstract

The present invention relates to the production of direct reduced iron DRI wherein the direct reduction of hydrogen is operated in conjunction in an industrial plant environment. The hydrogen reduction operates with a reducing gas comprising at least 85vol.% hydrogen and receives a make-up hydrogen stream. At least a portion of the make-up hydrogen stream is produced in situ by at least one of the following means: (i) An electrolysis device configured to produce hydrogen from steam recovered from one or more components of the industrial device and/or from steam generated using waste heat and/or hot gases exhausted from the one or more components; and (ii) a gas shift reactor device configured to convert CO-containing gas emitted by at least one component of the industrial device to hydrogen and remove CO2.

Description

Intelligent hydrogen production for DRI manufacture

Background

The necessity and responsibility for reducing global carbon dioxide emissions is affecting the steel industry as one of the major responsible participants. Global decarburization is pushing iron and steel enterprises towards more sustainable production transformation based on H2 DRI processes.

For the current reduction of CO ₂ Hydrogen is a new key factor in the production of new and especially future decarbonated steel (green hydrogen).

Today, the main integrated hydrogen production processes are:

i) Steam reforming of natural gas

This process is the most common and cheapest source of industrial hydrogen.

Natural gas is heated to 700-1100 ℃ in the presence of steam and a nickel catalyst. Methane molecules break down to form carbon monoxide and hydrogen. The carbon monoxide gas is passed through iron oxide or other oxides along with steam and further hydrogen is obtained by the water gas shift reaction.

Hydrogen produced in this way is economically attractive but requires fossil fuels and CO capture ₂ To avoid emissions.

ii) an electrolysis unit

The water-based electrolysis unit consists of several cells, each consisting of one anode and one cathode immersed in an electrolytic solution and connected to a power source. Electricity dissociates the inlet water stream into hydrogen and oxygen.

The steam supply electrolysis unit instead uses steam as an input to produce hydrogen and oxygen, based on substantially the same principle as a water-based electrolysis unit.

The water supply to the electrolysis unit is expensive from the standpoint of capital expenditure (Capex) and operating expense (OpEx). Steam feed electrolysis units are expensive from a capital expenditure and operating expense standpoint; due to its higher efficiency, it is less costly to operate than the water supply electrolysis unit.

Object of the Invention

Thus, hydrogen production is currently associated with Gao Cheng, such that the primary motivation is to find new and alternative and sustainable solutions to use hydrogen to reduce the associated costs.

Disclosure of Invention

The aim of the present invention is to find an attractive arrangement to produce hydrogen in a sustainable and competitive manner in an industrial environment.

An apparatus and method for producing DRI in a direct hydrogen reduction (DR) plant is disclosed.

Hydrogen (H) for hydrogen DR plant ₂ ) Production is achieved by an innovative arrangement using a gas shift reactor device and/or steam feed electrolysis unit for the production of hydrogen using energy carriers already present in the complex steelmaking plant (or more generally the industrial site).

The energy carrier is steam and/or CO-containing gas.

According to the present invention, a method for producing Direct Reduced Iron (DRI) includes:

operating a hydrogen Direct Reduction (DR) unit, wherein iron ore is reduced in a shaft furnace under a hydrogen reducing atmosphere, the shaft furnace being connected to a process gas loop arranged to receive top gas from the shaft furnace, to treat the top gas before heating the top gas in a heating device, and thereby to return a reducing gas comprising at least 85vol.% (volume percent) of hydrogen to the furnace, wherein a hydrogen stream (commonly referred to as make-up hydrogen) is added to the process gas loop upstream of the heating device;

operating an industrial plant producing CO-containing gas and/or steam and/or waste heat and/or hot gas;

wherein at least part of the hydrogen stream (make-up hydrogen stream) is produced by at least one of the following means:

an electrolysis device configured to produce hydrogen from steam recovered from one or more components of the industrial device and/or from steam generated using waste heat and/or hot gases exhausted from the one or more components; and

a gas shift reactor device configured to convert CO-containing gas emitted by at least one component of the industrial device into hydrogen-rich gas, and preferably to remove CO2.

The "hydrogen DR device" may be a DR device supplied with hydrogen as a reducing gas, wherein the hydrogen content of the reducing gas is between 85vol.% and 100vol.%, preferably higher than 85vol.% or 90vol.%, for example between 90vol.% and 95 vol.%. Such hydrogen DR plants typically comprise a shaft furnace and an associated recycle gas loop (referred to as a process gas loop) through which the top gas is treated (typically cleaned and compressed) and heated for recycle into the furnace as a reducing gas having the above-mentioned hydrogen content. An optional fuel gas loop (using part of the recycled top gas) may be used for heating in the heating apparatus. Depending on the process requirements, hydrogen provided by a hydrogen stream (commonly referred to as a make-up hydrogen stream) is added to the process gas loop in an amount sufficient to achieve the hydrogen concentration range described above. The effect of the make-up hydrogen stream is thus to make up the amount of hydrogen in the process loop to achieve the desired H in the reducing gas ₂ The concentration was run. The hydrogen make-up stream may typically have from 90vol.% to 100vol.% H ₂ The content is as follows. The hydrogen DR device may typically be a MIDREX H2 device.

The steam may be recovered from any component of the industry where steam is available. Alternatively or additionally, the steam may be produced by any known heat recovery device using a waste heat source present in the industrial process, which would otherwise represent heat loss. The heat recovery apparatus may generally include a heat exchanger configured to bring the hot gas/waste heat and water into heat exchange relationship to produce steam. The heat recovery device may for example comprise a boiler in which water is heated by hot gas/waste heat.

The steam thus generated is supplied to one or more steam supply electrolysis units, which may convert the steam into hydrogen and oxygen by using electricity as input. Any suitable electrolysis unit capable of separating oxygen from water vapour may be used, such as a Solid Oxide Electrolysis Cell (SOEC).

CO-containing gas represents any available industrial gas having a substantial carbon monoxide content (e.g., at least 20vol.% or more, in some embodiments 20vol.% to 25vol.%, although other gases having higher CO concentrations may be used). In the context of iron production, the CO-containing gas may be any metallurgical gas present in the whole plant with a considerable carbon monoxide content (e.g. BF (blast furnace) gas, BOF (basic oxygen furnace) gas, TGF (hot heavy furnace) gas, SAF (submerged arc furnace) off-gas, etc.), preferably with a low nitrogen content. Conversion of CO-containing gas to carbon dioxide CO using equipment based on Water Gas Shift (WGS) technology and CO2 removal ₂ The stream, that is to say separated from the remaining gas, i.e. the remaining gas is essentially a hydrogen-rich gas stream. Different techniques may be used, such as those in the art for pre-combustion CO2 capture. Hereinafter the plant will be named gas shift reactor device (GSRP). As known in the art, GSRP may comprise a WGS reactor in combination with a CO2 capture plant (e.g., amine technology). Alternatively, an integrated technology may be used, wherein a single reactor is configured to effect the WGS reaction and separate CO2. These techniques are known in the art and do not require further detailed description.

Any conventional steam supply electrolysis unit, any GSRP apparatus and any heat recovery device suitable for generating steam may be used in the context of the present invention.

In some embodiments, the hydrogen DR device is combined with a natural gas DR device present in an industrial site.

The natural gas DR plant may typically be a MIDREX NG plant; alternatively, it may be replaced with a MIDREX MxCOl device or an NG/H2 device.

Natural gas DR plants are typically operated on reformed natural gas to produce from iron oreProducing DRI. Comprising a further shaft furnace and a further process gas loop comprising a heating reformer to produce synthesis gas from natural gas (and recycled process gas). The synthesis gas is used as a reducing gas in a further shaft furnace, the typical composition of the reducing gas fed to the furnace being about 30-34vol% CO, 0-4% CO ₂ 50-55% H ₂ 2-6% H ₂ O, 1-4% CH ₄ 0-2% N ₂ 。

As will be clear to a person skilled in the art, natural gas DR plants emit top gas, which is hot gas and contains CO. Conventional natural gas DR plants may operate in conjunction with hydrogen DR plants to reduce the need for hydrogen from external sources. The same is true for MxCOl and NG/H2 devices.

In some embodiments, the method includes recovering heat from the natural gas DR plant to produce steam and producing hydrogen in the electrolysis plant.

This can be done at several locations in the natural gas DR plant:

-heat recovery means may be arranged on the further process gas circuit of the natural gas DR device, in particular upstream of the dust removal means, to recover heat from the recycled top gas and to generate steam which is fed to the electrolysis device;

the heat recovery device may be arranged to recover heat from the flue gas of the heating reformer of the process gas loop from the natural gas DR device, in particular before the stack of the natural gas DR device, to produce steam;

the heat recovery means may be arranged to recover heat from the hot DRI produced by the natural gas DR means (e.g. in the form of its HDRI, HBI or CRDI) to produce steam.

Steam can be generated by recovering heat in the same manner (same location) in MxCol and NG/H2 units to produce hydrogen by electrolysis.

Industrial sites may typically include Electric Arc Furnaces (EAFs), particularly for melting DRI produced in one of the DR plants or elsewhere. At the EAF, a heat recovery device may advantageously be arranged to recover heat from the hot gas/waste heat discharged from the EAF to produce steam (fed to the electrolysis unit).

In some embodiments, the method includes extracting CO-containing gas from the natural gas DR device and supplying the extracted CO-containing gas to the gas shift reactor device to produce hydrogen. A first stream of CO-containing gas may be tapped off from the process gas loop, preferably downstream of the compressor unit. The second stream of CO-containing gas may be tapped off after the dust removal device.

In some embodiments, the method may include recovering heat using one or more heat recovery devices disposed at one or more locations in the hydrogen DR device, and supplying the generated steam to the electrolysis device.

The heat recovery means may also be arranged on the process gas circuit of the hydrogen DR device, in particular upstream of the dust removal means, to recover heat from the recycled top gas and to generate steam which is fed to the electrolysis device.

The heat recovery device may be arranged to recover heat from the hot DRI produced by the hydrogen DR plant to produce steam that is fed to the electrolysis device.

In general, the heat recovery device may be arranged to recover heat from one or more components within the industrial device, in particular from the EAF; recovering heat from one or more DRI heat recovery systems (from any DR unit); heat is recovered from any DR unit.

According to another aspect, the invention relates to an apparatus comprising:

an industrial plant comprising at least one component that produces CO-containing gas, waste heat and/or steam and/or hot gas;

a hydrogen Direct Reduction (DR) unit comprising a shaft furnace and a process gas loop, wherein iron ore is reduced in the shaft furnace under a hydrogen reducing atmosphere, the process gas loop being arranged to receive top gas from the shaft furnace, treat the top gas before heating the top gas in a heating unit, and thereby return to the furnace a reducing gas comprising at least 80vol.% hydrogen, wherein a hydrogen stream is added to the process gas loop upstream of the heating unit;

the hydrogen production device comprises at least one of the following devices:

i) An electrolysis device configured to produce hydrogen from steam recovered from one or more components of the industrial device, and/or from steam produced by a heat recovery device configured to produce steam from waste heat and/or hot gases discharged from the one or more components; and

ii) a gas shift reactor device configured to convert CO-containing gas emitted by the industrial device into hydrogen (preferably to remove associated CO 2);

wherein the hydrogen stream produced by the hydrogen production device is at least partially fed to the hydrogen DR device for addition to the process gas loop.

The apparatus may generally be configured to implement the methods described above.

According to another aspect, the invention relates to a method of operating a hydrogen DR plant, comprising recovering heat with a heat recovery device arranged at one or more locations in the hydrogen DR plant, and supplying the generated steam to an electrolysis plant to produce hydrogen, which in turn is at least partially supplied to a process gas loop of the hydrogen DR plant.

The heat recovery means may be arranged on the process gas loop of the hydrogen DR device, in particular upstream of the dust removal means, to recover heat from the recycled top gas and to generate steam which is fed to the electrolysis device.

The heat recovery device may be arranged to recover heat from the DRI heat recovery system of the hydrogen DR plant to produce steam that is fed to the electrolysis device.

According to yet another aspect, the present invention relates to a system for carrying out the aforementioned method (see example 4 below).

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which fig. 1 to 4 relate to different embodiments of the invention.

Detailed Description

Industrial sites are characterized by the availability of steam and CO-containing gas. In this case, H as in the following embodiment ₂ Direct reduction devices (e.gH2 With the result that they are fully integrated into existing industrial sites.

As will be seen, the present invention proposes an arrangement in which the DR device is fully integrated in an industrial site (in particular in a metallurgical plant). The present invention focuses on the production of H2 in these industrial sites by utilizing a synergistic co-hydrogen DR plant.

In the following examples, the hydrogen operated DR device is, for example, MIDREX H2 ^TM Type (2).

In some embodiments, the hydrogen DR device is installed at a site having a natural gas operated DR device, for example, of the MIDREX NG type.

Example # 1-innovative version of FIG. 1

Referring now to fig. 1, a first embodiment of the present invention is shown wherein a hydrogen DR plant 10 operating with hydrogen as a reducing gas is integrated in an existing metallurgical site 12.

The DR device 10 generally corresponds to the MIDREX H2 process. As is known, it comprises a vertical shaft 16 with a top inlet 18 and a bottom outlet 20. Iron ore charge, in the form of nuggets and/or pellets, is charged into the top of the furnace and allowed to descend through the reducing gas due to gravity. During the travel from the inlet to the outlet, the charge remains solid. As indicated by arrow 22, the reducing gas (mainly consisting of H ₂ Composition) is introduced laterally into the shaft furnace, the reducing gas being introduced at the base of the reduction zone, flowing upwardly through the deposit. In the upper section of the furnace, in the H-rich zone ₂ In the reducing atmosphere of (2), the reduction of iron oxide occurs at a temperature in the range of 850-950 ℃. The solid products, i.e. Direct Reduced Iron (DRI) or reduced sponge iron, are discharged after cooling or in a hot state, as indicated by CDRI (cold DRI), HDRI (hot DRI) and HBI (hot compacted iron).

According to the MIDREX H2 process, almost pure hydrogen is used as a reducing gas for a direct reduction furnace.

The ideal hydrogen content of the reducing gas is 100%. In practice, H ₂ The content can vary from 85 to 100vol.%, the remainder being made up of N2, CO2,H2O and CH 4. These components are produced from H2 supplemented purity and final added natural gas as known in the art.

As known to those skilled in the art, MIDREX H2 is similar to a standard natural gas processExcept that the H2 input gas is generated outside the process. Therefore, the reforming process need not be performed, but only heat transfer is performed to heat the gas to a desired temperature.

Because of H ₂ Conversion to H ₂ O and condenses in the top gas scrubber, so no CO2 removal system is needed (unless the NG (natural gas) addition is particularly high as described above).

Referring to the drawings, the direct reduction furnace 16 is connected to a top gas circulation loop (or process gas loop) 24 that includes a scrubber 26, a compressor unit 28, and a heating device 30. The top gas leaving the direct reduction furnace 16 thus flows through a scrubber 26 where it is dedusted and condensed with water and further to a compressor unit 28. The amount of hydrogen in the process gas loop 24 is adjusted by adding a hydrogen stream (referred to as "hydrogen make-up") according to the process requirements. H in hydrogen make-up stream ₂ The content is preferably 90% to 100%. A hydrogen make-up stream (indicated at block 32 as a hydrogen source) is injected into the recirculation loop 24 between the compressor unit 28 and the heating device 30. The gas is then heated in the heating device 30 to the desired temperature range, whereby the reducing gas is ready for introduction into the furnace 16. The heating device 30 may be provided with thermal energy by an environmentally friendly heat source (such as waste heat, electricity, hydrogen, biomass) and/or natural gas may be required as fuel for the heating device.

As will be appreciated from this description, a majority of the hydrogen stream required for the reduction process may be produced in situ, reaching node 32. Alternatively, H2 may be added from an external source, although this should typically represent only a small portion of the hydrogen flow added to the process gas loop.

Recovering steam S1 from industrial site 12, which may have steam S1; or steam S1 may be produced using standard heat recovery equipment. For example, waste heat is directed to a heat exchanger to produce steam from water (e.g., boiler steam production).

The produced and/or recovered steam may be used to feed the steam feed electrolysis unit 3 and produce the feed stream directed to H ₂ Hydrogen flow A1 of DR unit.

Other steam streams S2 recovered from the industrial plant 12 or produced by the industrial plant 12 may be fed to the water gas shift reactor device 1 in combination with CO-containing gas G1 from gases produced by different processes present in the plant 12.

The gas shift reactor device (GSRP) 1 is designed to perform a water gas shift reaction that describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen:

GSRP 1 may be any suitable technology. Thus, two streams (steam S2 and CO-containing gas G1) from the industrial site 12 are fed thereto to produce two main streams, namely comprising carbon dioxide on the one hand and a hydrogen-rich gas stream (labeled stream A2) on the other hand. It should be understood herein that GSRP 1 is also configured for CO separation ₂ Thus, CO can be removed from the process ₂ . GSRP apparatus 1 may be conventional, based on any suitable technique.

The hydrogen-rich gas stream exiting GSRP 1 may optionally be used to separate N2 from the gaseous stream by nitrogen removal unit 2 (e.g., using a membrane or pressure swing adsorption).

The hydrogen stream A2 thus produced is fed to the node 32 where it is mixed with the first stream A1 and possibly with other H from an external source ₂ The streams are mixed. The hydrogen stream thus combined is introduced into the top gas recycle loop 24.

The CO-containing gas stream Gl may be compressed upstream of GSRP 1 by a compressor unit 34. A pressure recovery system (turbine) 36 may be arranged downstream of the WGS reactor apparatus 1 to recover energy from the hydrogen A2 stream and generate electricity to power the compressor 34.

With this integrated scheme, most of the hydrogen required for the H2 reduction process can be satisfied by the hydrogen produced by itself within the integrated unit.

Those skilled in the art will recognize the heat recovery potential of standard steelmaking plants based on BF-BOF flowsheet (i.e., steam produced by means of heat recovery in a sinter cooler, by means of dry quenching, etc.). Similarly, one skilled in the art should readily determine the amount and type of CO-containing gas (i.e., BF gas, BOF gas, SAF off-gas, etc.) available in standard steelmaking plants based on BF-BOF flowsheets.

A particularly interesting configuration is the described DRI-EAF device. Traditional practice of DRI-EAF plants is limited in heat recovery; CO-containing gases are generally not available nor can they be used to advantage.

Thus, in one embodiment, the present invention utilizes waste heat from the EAF and CO-containing gas to produce H2 via electrolysis and water gas shift reactions. This allows for reduced reliance on external H2 sources for operation of the DR apparatus.

It may be noted that the configuration of fig. 1 allows for selective operation based on steam or CO-containing gas. That is, the DR plant may be operated using H2 produced from steam generated by heat recovery from an industrial site (i.e., by electrolysis), or using H2 produced from CO-containing gas by the GSRP plant, or both.

Example # 2-scheme of FIG. 2

Example 2 is when H ₂ Details of example 1 when the Midrex device 10 is installed in an existing Midrex NG device 40.

As known to those skilled in the art, the Midrex NG plant 40 generally includes a shaft furnace 42 and a top gas recycle loop 44 having a top gas scrubber 46, a process gas compressor 48, a heat recovery system 50, and a reformer 52. The arrangement of the heat recovery system 50 and reformer 52 shown in fig. 2 is conventional for MIDREX NG plants, where synthesis gas (mainly CO and H2) is formed in the reformer 52 by reforming natural gas. The CO-containing recycle top gas is combined with natural gas to form a reduced feed gas to the furnace, preheated in heat recovery system 50, and then reacted in reformer 52 to produce synthesis gas stream SG. Natural gas, a portion of the top gas, and air are combusted in reformer 52 to maintain the reforming reaction and the flue gas is sent to heat recovery system 50 and further downstream to the environment (stack 54).

It will be appreciated that the steelmaking apparatus consisting of NG Midrex apparatus 40 and electric arc furnace 12 has different sources of waste heat which can be used to produce steam for supply to steam feed electrolysis unit 3 and to produce hydrogen to be used in Midrex H2 apparatus 10 (as shown in stream A1).

Steam generation is performed using heat recovery/steam generation equipment (e.g., boiler type) located at one or more of the following locations:

a heat recovery/steam generation unit 5 at a top gas outlet (5) on the circulation loop 44, generating a steam stream S4;

a heat recovery/steam generation unit 6 at the flue gas before the inlet of the stack 54, generating a steam stream S2;

a heat recovery/steam generation unit 7 at an EAF site 12, generating a steam stream S1; and

a heat recovery/steam generation unit 8 arranged to recover heat from the HBI cooling system generates a steam stream S5. Here, the HBI exiting furnace 42 extracts heat, but heat may also be obtained by heat removed from the CDRI cooling system.

The different steam streams S1 to S5 are combined with a mixing node 56 to form a cumulative stream S6 fed to the electrolysis unit 3, wherein a hydrogen stream A1 is produced and fed to the circulation loop 24 of the hydrogen operated DR device 10 by means of the node 32 (hydrogen make-up).

The total steam produced by all heat recovery units is integrated and the hydrogen make-up from an external source is reduced in different proportions depending on the size of each Midrex plant unit.

For reference, for 1MTPY NG Midrex, it is possible to save on 1MTPY H ₂ The Midrex unit has about 60-70% of the total metallurgical hydrogen.

Example # 3-scheme of FIG. 3

Example 3 represents additional details of example 1, which may be substituted (or added) for example 2.

Here, the hydrogen DR apparatus 10 is also coupled with the NG DR apparatus 40.

The portion of the CO-containing gas produced by the NG reduction process, here top gas fuel (stream R2) and/or process gas (stream R1), is directed from the NG recycle loop 44 and to GSRP 1 for production of gas for H ₂ Hydrogen stream C1 of the reduction process. CO produced by GSRP 1 ₂ Stream B1 is at least partially reintroduced in the NG reduction process in order to meet the predetermined CO in the reforming process ₂ Proportion.

A hydrogen stream C1 (optionally in combination with hydrogen from other sources) is introduced into the top gas recycle loop 24 of the hydrogen DR apparatus 10 upstream of the heater 30.

As in fig. 1, a compressor 34 is arranged before GSRP 1 to compress the CO-containing streams R1 and R2. The energy may be recovered using an optional pressure recovery turbine 36.

Table 1 below shows typical gas compositions of top gas fuel (stream R2) and process gas (stream R1).

％vol	Top gas fuel (R2)	Process gas (R1)
			CO	23.49	19.76
CO2	20.57	17.39
			H2	46.54	39.21
H2O	2.91	15.54
			N2	2.40	2.26
CH4	4.09	5.54
			Temperature (. Degree. C.)	35	172
Pressure (barg)	0.9	2.66

TABLE 1

Example # 4-scheme of FIG. 4

This last embodiment represents an additional possibility, which can be additionally implemented on the basis of the previous embodiments.

According to the configuration shown in FIG. 4, includes H ₂ Midrex units and Electric Arc Furnace (EAF) steelmaking units can self-produce a portion of the desired hydrogen in the hydrogen DR unit 10 by a reduction process. In this embodiment, steam is produced using different heat sources using heat recovery/steam generation equipment (e.g., boilers) located at one or more of the following locations:

a heat recovery/steam generation unit 60 at the top gas outlet of the furnace 16, prior to entry into the scrubber 26, generating a steam stream S7;

a heat recovery/steam generation unit 62 at the EAF site, generating a steam stream S9;

a heat recovery/steam generation unit 64 in combination with the HBI cooling system to produce a steam stream S8 (which may also be obtained by heat removed from the CDRI cooling system).

Streams S7, S8 and S9 (possibly together with additional steam streams from the industrial site network) are combined at mixing node 66, and the resulting steam stream S10 is fed to steam-fed electrolysis unit 3 to produce hydrogen stream A1.

Heat recovery alternatives (10, 11 and/or 12) and electrolysis units can be easily integrated in the embodiment of fig. 3

Advantages and advantages

Operational cost (OpEx)/capital expenditure (Capex) advantage

H ₂ Conventional operation of DR plants today has the disadvantage of high operating costs (and capital expenditures), which are associated with hydrogen production or purchasing hydrogen from an external source to the plant.

The present invention provides a technically flexible solution as it provides advantages both now and in the future for market conditions to change.

If now the steam fed electrolysis unit is not entirely cost effective due to the current electricity price, its contribution to the process emphasizing the water gas shift technology can be minimized or shut down, which today appears to be the most attractive technology for producing hydrogen with the lowest operating costs compared to commercial hydrogen and electrolysis based hydrogen production purchased from the market.

In the future, electricity prices will decrease. The solution of electrolysis of the steam supply will be the most convenient way to produce hydrogen. The flexibility of the present embodiment provides the opportunity to utilize two different technologies depending on the most convenient market conditions.

Thus, whereas self-produced hydrogen can meet process requirements in varying proportions depending on process characteristics and plant size, the proposed innovative plant configuration can reduce both present and future costs associated with hydrogen utilization.

Environmental advantage

The proposed solution is based on electrolysis of a CO-containing gas and/or steam supply.

In the case of electrolysis using a steam supply, the hydrogen producedCan be called CO2 free ₂ Discharge (provided that electricity is generated accordingly).

In the case of CO-containing gas, hydrogen may be referred to at least as CO2 neutralization (because no additional CO2 is emitted, nor is additional fossil fuel needed, i.e., as compared to steam methane reforming).

Claims

1. A method of producing direct reduced iron DRI comprising:

operating a hydrogen direct reduction DR plant wherein iron ore is reduced in a shaft furnace under a hydrogen rich atmosphere, the shaft furnace being connected with a process gas loop arranged to receive top gas from the shaft furnace, treat the top gas before heating the top gas in a heating device and thereby return a reducing gas comprising at least 85vol.% hydrogen to the furnace, wherein a hydrogen stream is added to the process gas loop upstream of the heating device;

operating an industrial plant producing CO-containing gas and/or waste heat and/or hot gas;

wherein at least part of the hydrogen stream is produced by at least one of the following means:

a gas shift reactor device configured to convert CO-containing gas emitted by at least one component of the industrial device into hydrogen and remove CO ₂ 。

2. The method of claim 1, wherein,

the industrial plant comprises a natural gas DR plant operating on reformed natural gas to produce DRI from iron ore, the natural gas DR plant comprising a further shaft furnace and a further process gas loop comprising a heating reformer to produce synthesis gas from natural gas, the synthesis gas being fed as reducing gas to the further shaft furnace.

3. The method of claim 2, comprising recovering heat from the natural gas DR plant to produce steam and producing hydrogen in the electrolysis plant.

4. A method according to claim 3, wherein a heat recovery device is arranged on the further process gas circuit of the natural gas DR device, in particular in contact with top gas after leaving the shaft furnace, to recover heat from the circulating top gas and to generate steam which is fed to the electrolysis device.

5. A method according to claim 3 or 4, wherein a heat recovery device is arranged to recover heat from the flue gas of the heating reformer from the process gas loop of the natural gas DR device, in particular before the stack of the natural gas DR device, to produce steam.

6. A method according to claim 3, 4 or 5, wherein a heat recovery device is arranged to recover heat from the hot DRI produced by the natural gas DR device to produce steam.

7. A method according to any one of the preceding claims, wherein the industrial site comprises an EAF and a heat recovery device is arranged to recover heat from waste heat and/or hot gases discharged by the EAF to produce steam and possibly heat from downstream equipment.

8. The method according to any one of claims 2 to 7, comprising

Extracting CO-containing gas from the natural gas DR plant and feeding the extracted CO-containing gas to the gas shift reactor plant,

preferably, a first CO-containing gas stream is extracted from the process gas loop downstream of the compressor means and/or a second CO-containing gas stream is extracted in the process gas loop after the dust removal means.

9. The method of any one of the preceding claims, comprising recovering heat with a heat recovery device disposed at one or more locations in the hydrogen DR device and supplying the generated steam to the electrolysis device.

10. The method according to claim 9, wherein a heat recovery device is arranged on the further process gas loop of the hydrogen DR device, in particular in contact with top gas after leaving from the further shaft furnace, to recover heat from the recycled top gas and to generate steam which is fed to the electrolysis device.

11. A method according to claim 9 or 10, wherein a heat recovery device is arranged to recover heat from the hot DRI produced by the hydrogen DR device to produce steam which is supplied to the electrolysis device.

12. The method of any of the preceding claims, wherein the industrial device comprises one or more of a sintering device, a coke oven device, an electric arc furnace, a blast furnace, a Submerged Arc Furnace (SAF), a continuous caster, a rolling mill, a basic oxygen furnace, and the like.

13. A method according to any one of the preceding claims, wherein the process gas loop comprises a gas cleaning device and a compressor device upstream of the heating device, between which compressor device and heating device the hydrogen stream addition takes place.

14. The method of claims 1-13, wherein the hydrogen stream added to the process gas loop of the hydrogen DR device contains 90vol.% to 100vol.% H ₂ The method comprises the steps of carrying out a first treatment on the surface of the And optionally, hydrogen from another source is supplied to the hydrogen DR device.

15. An apparatus, comprising:

a hydrogen direct reduction DR plant comprising a shaft furnace in which iron ore is reduced under a hydrogen reducing atmosphere, and a process gas circuit arranged to receive top gas from the shaft furnace, to treat the top gas before heating the top gas in a heating device and thereby to return a reducing gas comprising at least 80vol.% hydrogen to the furnace, wherein a hydrogen stream is added to the process gas circuit upstream of the heating device;

a hydrogen production plant comprising at least one of the following:

-an electrolysis device configured to produce hydrogen from steam recovered from one or more components of the industrial device; and/or producing hydrogen from steam generated by a heat recovery device configured to generate steam from waste heat and/or hot gases discharged by the one or more components;

-a gas shift reactor device configured to convert CO-containing gas emitted by the industrial device into hydrogen and to remove CO ₂ ；

Wherein a hydrogen stream produced by a hydrogen production unit is at least partially fed to the hydrogen DR unit for addition to the process gas loop.