METHOD FOR OPERATING A BLAST FURNACE INSTALLATION

Abstract

A method for operating a blast furnace is presented, said method comprising the steps of collecting a stream of blast furnace gas from the blast furnace; feeding said stream of blast furnace gas and a hydrocarbon containing gas to a reforming plant comprising at least one reformer; reforming said stream of blast furnace gas and said hydrocarbon containing gas in the reforming plant en to produce a stream of syngas; and feeding at least a portion of said stream of syngas to the blast furnace; wherein a stream of h % is added to the hydrocarbon containing gas before step (c) and/or to the stream of blast furnace gas before step (c) and/or to the stream of syngas before step (d) and/or to the tuyere of the blast furnace, wherein the feeding of at least a portion of said stream of syngas to the blast furnace occurs through the shaft of the blast furnace and/or through the tuyere of the blast furnace, and wherein the utilization efficiency of the hydrogen in a blast furnace plant comprising the blast furnace, the reforming plant and a cowper plant is above 60%.

Claims

1. A method for operating a blast furnace, comprising the steps of a. collecting a stream of blast furnace gas from a blast furnace having a shaft and at least one tuyere; b. feeding said stream of blast furnace gas and a hydrocarbon containing gas to a reforming plant comprising at least one reformer; c. reforming said stream of blast furnace gas and said hydrocarbon containing gas in the reforming plant to produce a stream of syngas; and d. feeding at least a portion of said stream of syngas to the blast furnace; wherein a stream of is added to the hydrocarbon containing gas before step (c) and/or to the stream of blast furnace gas before step (c) and/or to a mixture comprising the blast furnace gas and the hydrocarbon containing gas before step (c) and/or to the stream of syngas before step (d), and wherein the feeding of at least a portion of said stream of syngas to the blast furnace occurs through the shaft of the blast furnace.

2. A method for operating a blast furnace, by improving the efficiency of hydrogen utilisation in a blast furnace, the method comprising the combination of H.sub.2 addition to the blast furnace, with a reforming reaction, wherein the part of hydrogen utilization in a blast furnace installation comprising the blast furnace, a reforming plant and a cowper plant is above 60% of the hydrogen fed to the blast furnace, wherein the hydrogen utilization is defined as: (hydrogen input to the blast furnace installation-hydrogen export from the blast furnace installation)/(hydrogen input to the blast furnace installation), wherein the hydrogen fed to the blast furnace is defined as the total hydrogen content of the gas in a cohesive zone of the blast furnace and of the shaft gas injected to the blast furnace at shaft level and the hydrogen fed to the blast furnace is totaling a flow of minimum 200 Nm.sup.3/t of produced hot metal and out of which a minimum of 50 Nm.sup.3/t of hot metal are fed to the blast furnace installation in form of molecular hydrogen H.sub.2, wherein the hydrogen input to the blast furnace includes in particular the hydrogen contained in the syngas, in the injected molecular hydrogen H.sub.2, in the other hydrogen containing gases, in the injected coal and/or tar, in the humidity of the injected gases and solid fuels and in the humidity of the hot blast.

3. The method as claimed in claim 1, wherein the feeding of at least a portion of said stream of syngas to the blast furnace occurs through the shaft of the blast furnace and through the at least one tuyere of the blast furnace.

4. The method as claimed in claim 1, wherein at least a part of the hydrogen fed to the blast furnace installation is injected through the tuyere of the blast furnace.

5. The method according to claim 1, wherein the feeding of at least a portion of said stream of syngas to the blast furnace occurs through the shaft of the blast furnace and through the tuyere of the blast furnace.

6. The method according to claim 1, wherein the stream of H.sub.2 is added to the stream of syngas with a temperature below 600? C.

7. The method according to claim 1, wherein the stream of blast furnace gas and/or the stream of hydrocarbon containing gas is hydrogenated and/or desulphurised in a hydrogenation and desulphurization unit upstream of the reforming plant.

8. The method according to claim 7, wherein at least part of the hydrogen is added to the stream of hydrocarbon containing gas upstream of the hydrogenation and desulphurization unit.

9. The method as claimed in claim 1, wherein the stream of H.sub.2 is produced by electrolysis in an electrolysis cell.

10. The method as claimed in claim 9, wherein an electric power for operating the electrolysis cell is produced by a renewable source.

11. The method as claimed in claim 1, wherein the hydrocarbon containing gas comprises natural gas, coke oven gas and/or biogas.

12. The method as claimed in claim 1, wherein the at least one reformer of the reforming plant is a regenerative reformer.

13. The method as claimed in claim 1, wherein the at least one reformer of the reforming plant is a catalytic dry and/or wet reformer of any type, in particular bottom fired, side fired, terrace type or top fired.

14. The method as claimed in claim 1, wherein the reforming plant comprises two reformers, in particular a pre-reformer and a main reformer.

15. The method as claimed in claim 1, wherein the reforming at step (c) is performed non-catalytically.

16. The method as claimed in claim 1, wherein the reforming at step (c) is combined with a partial oxidation of hydrocarbons.

17. The method as claimed in claim 1, wherein a reduction potential of the syngas (26, 28) produced at step (c) is higher than 6, wherein the reduction potential is defined by the molar ratio (cCO+cH.sub.2)/(cH.sub.2O+cCO.sub.2).

18. The method as claimed in claim 1, wherein the reforming at step (c) is performed at a temperature above about 900? C.

19. The method as claimed in claim 1, wherein the stream of blast furnace gas is further subjected to a gas cooling and/or cleaning and/or pressurization step, a vapor removal step, a dust removal step, metals removal step, HCl removal step and/or sulfurous component removal step, before being fed to the reformer.

20. The method as claimed in claim 1, wherein a stream of steam is added to the hydrocarbon containing gas and/or a stream of steam is added to the blast furnace gas after the cleaning step.

21. The methods as claimed in claim 1, wherein a stream of blast furnace gas is used in the burners of the reforming plant.

22. A blast furnace installation comprising a blast furnace provided with a shaft, tuyeres arranged for feeding a first stream of a hydrogen containing gas to the blast furnace and gas inlets in the shaft of the blast furnace arranged for feeding a stream of syngas to the blast furnace, said blast furnace installation further comprising: a reforming plant comprising at least one reformer in fluidic connection with the top of the blast furnace and with a source of a hydrocarbon containing gas, said reformer being arranged for converting a stream of blast furnace gas and the hydrocarbon containing gas to a stream of syngas and being in fluidic downstream connection with said gas inlets in the shaft of the blast furnace; and a source of a stream of H.sub.2 in fluidic connection with the at least one reformer and/or with the gas inlets in the shaft and/or the tuyere of the blast furnace.

23. The blast furnace installation as claimed in claim 22, wherein the blast furnace installation is configured for implementing a method for operating a blast furnace comprising a. collecting a stream of blast furnace gas from a blast furnace having a shaft and at least one tuyere; b. feeding said stream of blast furnace gas and a hydrocarbon containing gas to a reforming plant comprising at least one reformer; c. reforming said stream of blast furnace gas and said hydrocarbon containing gas in the reforming plant to produce a stream of syngas; and d. feeding at least a portion of said stream of syngas to the blast furnace: wherein a stream of H.sub.2 is added to the hydrocarbon containing gas before step (c) and/or to the stream of blast furnace gas before step (c) and/or to a mixture comprising the blast furnace gas and the hydrocarbon containing gas before step (c) and/or to the stream of syngas before step (d), and wherein the feeding of at least a portion of said stream of syngas to the blast furnace occurs through the shaft of the blast furnace.

24. The blast furnace installation as claimed in claim 22, wherein the reformer is in fluidic downstream connection with the tuyeres of the blast furnace and with the gas inlets in the shaft of the blast furnace.

25. The blast furnace installation as claimed in claim 22, wherein the reforming plant comprises a regenerative reformer.

26. The blast furnace installation as claimed in claim 22, wherein the reforming plant comprises a catalytic dry and/or wet reformer, and/or wherein the reforming plant comprises two reformers, in particular a pre-reformer and a main reformer.

27. The blast furnace installation as claimed in claim 22, wherein the reforming plant further comprises a partial oxidation reactor.

28. The blast furnace installation as claimed in claim 22, wherein the fluidic connection with the top of the blast furnace arranged for conveying a stream of blast furnace gas to the reforming plant further comprises a gas cooling and/or cleaning and/or pressurizing plant, a vapor removal unit, a dust removal unit, metals removal unit, HCl removal unit and/or sulphurous component removal unit.

29. The blast furnace installation as claimed in claim 22, wherein the fluidic connection with the top of the blast furnace arranged for conveying a stream of blast furnace gas to the reforming plant further comprises a pressuring unit and/or a hydrogenation and desulphurization unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Preferred embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:

[0082] FIG. 1 is a schematic view of an embodiment of a first variant of a blast furnace plant configured to implement the present blast furnace operating method;

[0083] FIG. 2 is a schematic view of an embodiment of a second variant of a blast furnace plant configured to implement the present blast furnace operating method;

[0084] FIG. 3 is a schematic view of an embodiment of a third variant of a blast furnace plant configured to implement the present blast furnace operating method; and

[0085] FIG. 4 is a graph showing the variation of C.sub.2H.sub.4 concentration in a reformer as a function of the temperature for various hydrogen content.

DETAILED DESCRIPTION

Co.SUB.2 .Emissions:

[0086] Coke is the main energy input in the blast furnace iron making. From the CO.sub.2 and often also from the economic point of view, this is the less favorable energy source. Substitution of coke by other energy sources, mostly injected at tuyere level, is widely employed. Due to cost reasons mostly pulverized coal is injected, however in countries with low natural gas price, this energy is used. Often residues like waste plastics are also injected in the blast furnace. In an ambition of reduction of greenhouse gas emissions, industrial operations start to incorporate also hydrogen in their auxiliary fuels and with the expected higher availability of hydrogen it is expected that the contribution of hydrogen as auxiliary fuel will strongly increase.

[0087] These auxiliary fuels may have a positive impact on the CO.sub.2 emissions from the blast furnace steel making, meanwhile their utilization is limited to process reasons and very often these limits are already reached today. The blast furnace produces blast furnace gas (BFG), which contains up to approximately 40% of the energy input to the blast furnace. About 25% of that blast furnace gas leaving the blast furnace is normally used in the cowper plant for heating of the blast that is injected at the tuyeres of the blast furnace. The remaining 75% of that blast furnace gas, containing about 30% of the energy input to the blast furnace is generally used for internal heat requirements in the steel plant, but also for electric energy production.

[0088] For reducing the CO.sub.2 footprint of a blast furnace-based steel production, one important strategy is thus to use as much as possible of this BFG for metallurgical purposes and apply other CO.sub.2 lean energies such as green electric energy for the remaining energy requirement of the steel plant.

[0089] Hence, the synthesis gas production should, beside the utilization of a CO.sub.2 lean hydrocarbon, also use blast furnace gas as much as possible in order to improve the CO.sub.2 emission reduction potential from the blast furnace iron making, as well as, if available in the blast furnace plant, converter gas and/or cold basic oxygen furnace (BOF) gas.

Hydrogen Utilization for Iron Making:

[0090] The hydrogen utilization for iron making can be divided in the direct utilization of the hydrogen in the blast furnace as well as its utilization in the auxiliary plants, specifically the cowper plant and if installed the reforming plant for the production of the syngas to be injected in the shaft of the blast furnace.

[0091] The utilization of hydrogen in the blast furnace is generally referred to as the eta H.sub.2. Eta H.sub.2 being defined as: eta H.sub.2=((H.sub.2 in BF)?(H.sub.2 out BF in top gas))/(H.sub.2 in BF). In the present text, BF means blast furnace, so that (H.sub.2 in BF) refers to the flow of H.sub.2 going into the blast furnace, and (H.sub.2 out BF in top gas) refers to the flow of H.sub.2 in the blast furnace top gas exiting the top of the blast furnace.

[0092] H.sub.2 in BF is defined as the total hydrogen content of the bosh gas (i.e. gas in the cohesive zone of the blast furnace) and of the shaft gas injected to the blast furnace at shaft level. This hydrogen input to the blast furnace includes in particular the hydrogen contained in the syngas, in the injected molecular hydrogen H.sub.2, in the other hydrogen containing gases, in the injected coal and/or tar, in the humidity of the injected gases and solid fuels and the humidity of the hot blast.

[0093] H.sub.2 out BF in top gas is defined in the dry flow rate of the top gas leaving the blast furnace times the dry concentration of hydrogen in that top gas.

[0094] The eta H.sub.2 is normally below 50% and often below 45%. The eta H.sub.2, and thus the percentage of hydrogen utilisation in the blast furnace, has furthermore the characteristic that it decreases with increasing hydrogen input into the blast furnace. This means when one wants to use more hydrogen in the blast furnace, the efficiency of its utilisation strongly decreases and a much bigger portion of the hydrogen introduced in the blast furnace is leaving it with the top gas. In consequence also the attainable coke rate reduction per kg of injected hydrogen decreases which indirectly reduces the CO.sub.2 reduction potential of the injected hydrogen.

[0095] Moreover, when increasing the injection of auxiliary fuel (i.e. hydrogen containing gas), the enrichment of oxygen must be increased in order to maintain the flame temperature. Increasing the oxygen enrichment in the blast furnace signifies reducing the amount of natural blast (air) that will be used in the blast furnace. In consequence the overall amount of hot blast entering the blast furnace is decreased. This means that less blast furnace gas can be used for heating the hot blast.

[0096] This finally means that when increasing the percentage of hydrogen in the blast furnace for the reduction of iron ore, a smaller part of this hydrogen is used within the blast furnace and a smaller part of it is used in the cowper plant resulting in an increased amount of hydrogen leaving the blast furnace plant in the export gas.

[0097] This is shown in the following table (Table 1) which is comparing a reference operation of a blast furnace and operation of a blast furnace with hydrogen injection according to three embodiments of the present inventive method.

TABLE-US-00001 TABLE 1 Case 3: Case 2: Max H.sub.2 Case 1: H.sub.2 injection + injection + H.sub.2 shaft shaft Item Unit Reference injection syngas syngas 1 Hot metal (HM) production t HM/h 300 300 300 300 2 Coke rate t/h 90.3 87.12 67.35 63.03 3 Pulverised coal injection t/h 57.6 57.6 57.6 57.6 4 Natural gas used for Nm3/h 0 0 9993 9993 syngas production 5 H.sub.2 injection at tuyere Nm3/t HM 38 38 109 6 Syngas injection at shaft Nm3/h 120000 120000 of blast furnace 7 H.sub.2 contained in syngas Nm3/h 61963 64485 injected at shaft 8 H.sub.2 in bosh gas Nm3/h 30322 41520 41062 60821 9 H.sub.2 in total Nm3/h 30322 41520 103025 125306 10 H.sub.2 out topgas Nm3/h 15901 21860 62053 76261 11 Eta H.sub.2 (H.sub.2 utilisation in 47.6% 47.4% 39.8% 39.1% blast furnace) 12 Top gas energy GJ/h 1469531 1475909 1978421 2057046 13 Heat requirement hot GJ/h 541180 494746 392866 313884 stove plant 14 Top gas requirement GJ/h 575753 654788 syngas reactor 15 Top gas export GJ/h 928351 981163 1009801 1088374 16 H.sub.2 export Nm3/h 10045 14532 31672 40349 17 H.sub.2 export ratio 33% 35% 31% 32% 18 H.sub.2 utilisation in blast 67% 65% 69% 68% furnace plant 19 CO.sub.2 emissions resulting t/h 0 0 0 0 from coke, pulverized coal and natural gas

[0098] In the reference operation, the blast furnace uses only coke and pulverised coal injection at the tuyere, whereas in case 1, cold hydrogen is additionally injected at the tuyere level of the blast furnace.

[0099] One can see in case 1, that the ratio of the export hydrogen from the blast furnace plant increases by 4.487 Nm.sup.3 from 10.045 Nm.sup.3/h (for the reference) to 14.532 Nm.sup.3/h (for case 1) for an increase of the hydrogen input in the blast furnace by 11.198 Nm.sup.3 from 30.322 (for the reference) to 41.520 Nm.sup.3/h (for case 1). This results in a decrease of the hydrogen utilisation in the blast furnace plant from 67 to 65%. In other words, the 4.487 Nm.sup.3 that leave the blast furnace plant in the top gas represent 40% of the additional injected hydrogen of 11.198 Nm.sup.3, thus the utilisation of the additional hydrogen in the blast furnace is much lower and 60% only.

[0100] In case 2 (Table 1) a hot syngas is injected at the shaft of the blast furnace at 950? C. One can see now even though that the total amount of hydrogen injected in the blast furnace is more than tripled in comparison to the reference case, its utilisation in the blast furnace plant is increased from 67 to 69%. This is very impressive since this shows that only a small addition of hydrogen to the blast furnace at the tuyere level already impacts in decreasing the utilisation of the hydrogen in the blast furnace plant. Compared to the reference case, the additional injection of 72.703 Nm.sup.3 of hydrogen, only 21.627 Nm.sup.3 or 30% are leaving the blast furnace plant with the export gas.

[0101] In the last case shown in Table 1 (case 3), the amount of hydrogen entering the blast furnace was considerably increased, i.e. more than quadrupled compared to the reference case. Even now one can see that the utilisation of the hydrogen within the blast furnace plant is higher as in the reference case. Out of the additional injection of 94.984 Nm.sup.3 of hydrogen, only 30.304 Nm.sup.3 or 32% are leaving the blast furnace plant with the export gas.

Energy Efficiency

[0102] In order to achieve an overall high efficiency of the process, the cowper plant as well as the reforming plant shall preferably be equipped with heat recovery systems for preheating the combustion air and/or combustion gas. The efficiency of both plants should be above 70%, more specifically above 80%.

Reforming and Syngas Requirements:

[0103] The requirements for the syngas for its utilization in the blast furnace are different to the requirements for applications in other industries.

[0104] The main requirements for syngas utilization in the blast furnace are as follows:

Reduction Potential and Temperature Level of the Syngas:

[0105] In other industries the syngas is normally produced and then cooled to separate the excess of steam from the syngas. Thereby only cooled gas is used in the downstream processes. In existing industrial applications beside the steel industry, a high reduction potential directly achieved by the reforming process is therefore not important. In the steel industry however a high reduction potential, preferably as high as possible and at least above 6, is preferable and highly advantageous for a high process efficiency, the reduction potential, or reduction degree, being defined as: (cCO+cH.sub.2)/(cH.sub.2O+cCO.sub.2), where c means the molar concentration, such that e.g. cCO means the molar concentration of CO in the syngas, cH.sub.2 means the molar concentration of H.sub.2 in the syngas, cH.sub.2O means the molar concentration of H.sub.2O in the syngas and cCO.sub.2 means the molar concentration of CO.sub.2 in the syngas.

[0106] Furthermore, high temperatures of syngas are favoured and compatible to the temperature level required for shaft injection through the tuyere and/or through the shaft in order to allow maximum thermal efficiency. Thus, the temperature should be between 850 to 1100? C., preferably about 950? C., to allow its injection in the shaft above the cohesive zone of a blast furnace, i.e. at the shaft level.

Ratio H.SUB.2./CO:

[0107] In the other industries, beside steel industry, the syngas is used for specific applications, such as pure hydrogen production, ammonia or the production of other chemical components. Thereby a specific ratio of hydrogen to CO within the syngas is generally required.

[0108] In comparison, using syngas is used in a blast furnace for the reduction of ore, which is achieved with both reducing components, CO and hydrogen. While there is a difference between the reduction of ore with CO or hydrogen, this difference is relatively marginal considering that syngas is only one part of the reducing gas used within the blast furnace.

Pressure Level:

[0109] Whereas in other industries the pressure levels of the reformers are relatively high, mostly above 20 barg or even above 40 barg, in the blast furnace application the required pressure level is 1.5 to 6 barg only. This has an important impact on the operating conditions and limits of the reforming equipment such as soot formation and equilibrium conversion. Whereas the lower pressure level will favor a higher methane conversion at the same temperature level, it unfortunately also favors the formation of soot, reason for which the addition of a stream of H.sub.2 to the stream of blast furnace gas and/or to the hydrocarbon containing gas upstream of the reformer is specifically advantageous to partially suppress soot formation, even if it simultaneously lowers the conversion of methane at a given temperature in comparison without hydrogen addition.

Hydrogen Addition:

[0110] As already shown above the hydrogen can simply be added at the tuyere of the blast furnace, in form of H.sub.2 and also in the form of hydrocarbon. However, it is possible to also use the hydrogen addition to positively impact the syngas production and its injection at the shaft of the blast furnace.

[0111] A stream of hydrogen, preferably renewable hydrogen, is added to the method, in particular before the reformer, reducing soot formation or after the reformer to the stream of syngas to be injected through the shaft in order to simultaneously cool it down and increasing its reduction potential. In the present text, and when referring to the syngas, reduction potential and reduction degree are used as synonym for one another and both refers to the molar ratio (cCO+cH2)/(cH2O+cCO2). Before addition of hydrogen upstream of the reformer, it may be beneficial to heat the stream of hydrogen.

Reforming Reactions for Syngas Production:

[0112] Hydrocarbon gas reforming, such as natural gas reforming can principally be performed by following reactions:

CH.sub.4+H.sub.2O=CO+3H.sub.2Steam reforming in the presence of steam:

CH.sub.4+CO.sub.2=2CO+2H.sub.2Dry reforming in the presence of CO.sub.2:

[0113] These two reactions are strongly endothermic and require a lot of heat.

[0114] This heat can be supplied indirectly by burning a fuel gas and transferring the flue gas heat to the reactor, or also by combining the reforming reaction with a partial oxidation reaction according the below formula:

##STR00001##

[0115] Along the reforming reactions, side reactions can occur in the reformer. The relative importance of these reactions depends on the operating conditions such as gas composition, temperature and pressure, use and nature of catalysts and the like.

[0116] The main side reactions at temperatures close to the reforming temperature are:

CO.sub.2+H.sub.2.fwdarw.CO+H.sub.2OReverse water-gas shift reaction (RWGS):

CH.sub.4.fwdarw.C+2H.sub.2CH.sub.4 decomposition:

4H.sub.2+CO.sub.2+CH.sub.4+2H.sub.2O or 3H.sub.2+CO.fwdarw.CH.sub.4+H.sub.2OMethanation reaction

[0117] As well as the multitude of reactions that are part of the reaction scheme for the production of soot/carbon deposit. Exemplarily for those reactions is the formation of acetylene, as shown below:

2CH.sub.4.fwdarw.C.sub.2H.sub.2+3H.sub.2Formation of acetylene:

[0118] This acetylene can then be a molecule (precursor) in the creation of aromatic hydrocarbons which are part of the soot or can be thermally decomposed according to following reaction:

C.sub.2H.sub.2+2C+H.sub.2Decomposition of acetylene:

[0119] Hydrogen is part of most of these reactions and will thus have an important impact on the reforming reaction itself but also on the side reactions. It is therefore possible to take advantage of the desired utilization of hydrogen in the blast furnace for CO.sub.2 reduction purposes to further improve the hydrocarbon reforming process, such as to reduce the soot formation and deposition, by adding H.sub.2 to the stream of blast furnace gas and/or the hydrocarbon containing gas upstream of the reformer.

Detailed Description of Three Different Embodiments of the Disclosure

[0120] In the following, three different variants of the method for operating a blast furnace and the blast furnace plant are shown in relation with the annexed drawings.

[0121] FIG. 1 illustrates an embodiment of a first variant of the present method for operating a blast furnace comprising the simultaneous injection of a first stream of syngas through the shaft of a blast furnace and of a second stream of syngas through the tuyere of the blast furnace.

[0122] Blast furnace gas 10 exiting the blast furnace 12 is collected at the top of a blast furnace 12.

[0123] The collected blast furnace gas 10 is generally pre-treated upon exiting the blast furnace. Pre-treatment of the stream of blast furnace gas comprises first a cooling to reduce its vapor content, a cleaning, in particular a removing of dust and/or HCl and/or metal compounds, and then a pressurization to have a pressure sufficient for an eventual desulphurization, the heating, the reforming process and injection in the blast furnace. In the embodiment of FIG. 1, the cooling, cleaning and pressurization of the blast furnace gas occurs in a cooling, cleaning and pressuring unit 14. Alternatively, separate units could be used, each unit performing either one of cooling, cleaning or pressuring the blast furnace gas. In other embodiments, one unit may be responsible for two of cooling, cleaning and pressuring the blast furnace gas, the third pre-treatment step being performed in a separate unit. In the present text, a cooling, cleaning and pressuring unit is a unit configured to cool, clean and pressurize a stream of gas, without assuming that it is mandatory to perform the various steps (cooling, cleaning and pressuring) in this order. In embodiments, the pressurization can take place upstream of the cleaning, such as e.g. in embodiments wherein the cleaning of the stream of gas is a desulphurization.

[0124] Downstream of the cooling, cleaning and pressuring unit 14, the stream of blast furnace gas is split in three streams. A first stream of blast furnace gas 16 is fed to a first reforming plant 18 and a second stream of blast furnace gas 20 is fed to a second reforming plant 22. In the present embodiment, both reforming plants are regenerative type reforming plants. A third stream of blast furnace gas 27 is referred to as blast furnace export gas and corresponds to blast furnace gas being fed to another unit of a steel making plant comprising the blast furnace plant with the reforming plants 18, 22.

[0125] Additionally, a stream 24 of coke oven gas and/or natural gas is fed to the reforming plants 18, 22.

[0126] Basic oxygen furnace gas and/or steam might optionally be added to the stream of blast furnace gas (upstream and/or downstream of the cooling, cleaning and pressuring unit 14) and/or the stream of hydrocarbon containing gas 24 and/or directly to a reforming plant 18, 22 (not shown).

[0127] A reforming of the first stream of blast furnace gas 16 along with the stream 24 of coke oven gas and/or natural gas is done in the first reforming plant 18 to produce a first stream of syngas 26. A reforming of the second stream of blast furnace gas 20 along with the stream 24 of coke oven gas and/or hydrocarbon containing gas is done in the reforming plant 22 to produce a second stream of syngas 28.

[0128] Both reforming processes are dry and/or wet reforming processes, possibly also in combination with a partial oxidation, leading to the formation of two streams of syngas 26, 28 with high CO and H.sub.2 contents. Reforming processes occurs at pressure between 1.5 and 10 barg and depending on the reforming plant at a temperature above 900? C., preferably above 950? C., more preferably above 1000? C.

[0129] Blast furnace gas and/or hydrocarbon containing gas might optionally be heated prior to the reforming process (not shown). Heating might be performed e.g. by using tube bundle heat exchangers. The second stream of syngas 28 exiting the second reforming plant 22 is fed to the blast furnace through the tuyere 30 with a temperature of about 1200? C. and a pressure of 2 to 6 barg.

[0130] Additionally, the blast furnace installation comprises an electrolysis cell 32 fueled by electrical power 34 to produce a stream of H.sub.2 36 by electrolysis, preferably by water/steam electrolysis. The electrical power 34 fueling the electrolysis cell 32 is preferably renewable or green, i.e. obtained from a renewable source such as wind, solar and/or hydropower.

[0131] Alternatively or additionally, said hydrogen can be produced from natural gas through a pyrolysis process with solid carbon formation, or with combined Carbon Capture and Storage (CCS) technology and/or Carbon Capture and Utilization (CCU) technology. Hydrogen might also be produced by methane thermal cracking or steam methane reforming with combined CCS and/or CCU technology.

[0132] The stream of H.sub.2 36 produced by the electrolysis cell is added to the first stream of syngas 26 downstream of the first reforming plant 18 and upstream of gas inlets 38 disposed through the shaft inside the blast furnace 12. The first stream of syngas 26 added with hydrogen 36 form a stream of H.sub.2-enriched gas 40, which is fed to the blast furnace through the gas inlets 38 at the shaft level, with a temperature of about 900? C. and a typical pressure of 1.5 to 4 barg.

[0133] The stream of H.sub.2 36 acts as a coolant of the first stream of syngas 26. Using said hydrogen in this way, i.e. as a coolant, completely eliminates the need of heating said hydrogen prior to its injection through the shaft of the blast furnace 12 in an expensive heating device. Indeed, the excess heat of the syngas 26 heats said hydrogen. This allows to increase the efficiency of the process by eliminating both the need for syngas cooling and hydrogen heating.

[0134] FIG. 2 illustrates an embodiment of a second variant of the present method for operating a blast furnace comprising the simultaneous injection of a first stream of syngas through the shaft of a blast furnace and of a second stream of syngas through the tuyere of the blast furnace.

[0135] Blast furnace gas 110 exiting the blast furnace 112 is collected at the top of a blast furnace 112.

[0136] The collected blast furnace gas 110 is generally pre-treated upon exiting the blast furnace. Pre-treatment of the stream of blast furnace gas comprises first a cooling to reduce its vapor content, a cleaning, in particular a removing of dust and/or HCl and/or metal compounds and/or sulfurous components, and then a pressurization to have a pressure sufficient for the reforming process and its injection in the blast furnace. In the embodiment of FIG. 2, the cooling, cleaning and pressurization of the blast furnace gas occurs in a cooling, cleaning and pressuring unit 114. Alternatively, separate units could be used, each unit performing either one of cooling, cleaning or pressuring the blast furnace gas. In other embodiments, one unit may be responsible for two of cooling, cleaning and pressuring the blast furnace gas, the third pre-treatment step being performed in a separate unit.

[0137] Downstream of the cooling, cleaning and pressuring unit 114, the stream of blast furnace gas is split in three streams. A first stream of blast furnace gas 116 is fed to a first reforming plant 118 and a second stream of blast furnace gas 120 is fed to a second reforming plant 122. In the present embodiment, both reforming plants are regenerative type reforming plants. A third stream of blast furnace gas 127 is referred to as blast furnace export gas and corresponds to blast furnace gas being fed to another unit of a steel making plant comprising the blast furnace plant with the reforming plants 118, 122.

[0138] Additionally, the blast furnace installation comprises, in addition to the blast furnace and the cooling, cleaning and pressuring unit 114, a source for a stream 124 of coke oven gas and/or natural gas in fluidic communication with each of the reforming plants 118, 122, and an electrolysis cell 132 fueled by electrical power 134 to produce a stream of H.sub.2 136 by electrolysis, preferably by water electrolysis. The electrical power 134 fueling the electrolysis cell 132 is preferably renewable or green, i.e. obtained from a renewable source such as wind, solar and/or hydropower.

[0139] The stream of H.sub.2 136 produced by the electrolysis cell is added to the stream 124 of coke oven gas and/or natural gas upstream of the reforming plants 118, 122 to form a stream of H.sub.2-enriched hydrocarbon containing gas 142, which is fed to each of the reforming plants 118, 122.

[0140] Basic oxygen furnace gas and/or steam might optionally be added to the stream of blast furnace gas (upstream and/or downstream of the cooling, cleaning and pressuring unit 114) and/or the stream of hydrocarbon containing gas 124 and/or to the stream of H.sub.2 136 and/or directly to a reforming plant 118, 122 (not shown).

[0141] A reforming of the first stream of blast furnace gas 116 along with the stream of H.sub.2-enriched hydrocarbon containing gas 142 is done in the first reforming plant 118 to produce a first stream of syngas 126. A reforming of the second stream of blast furnace gas 120 along with the stream of H.sub.2-enriched hydrocarbon containing gas 142 is done in the second reforming plant 122 to produce a second stream of syngas 128.

[0142] Both reforming processes are dry reforming, leading to the formation of two streams of syngas 126, 128 with high CO and H.sub.2 contents. Reforming processes occurs at pressure between 1.5 and 10 barg and depending on the reforming plant at temperatures above 900? C., preferably 1000? C., more preferably above 1200? C.

[0143] Blast furnace gas and/or hydrogen containing gas might optionally be heated prior to the reforming process (not shown). Heating might be performed e.g. by using tube bundle heat exchangers.

[0144] The addition of hydrogen to the hydrocarbon containing gas upstream of the reforming plants 118, 122, and thus prior to the reforming processes, will help to reduce the soot formation during the reforming reaction. The formation of carbon deposits through the dry reforming is a known problem. There are different reactions occurring inside the reforming plant and leading to the formation of carbon deposits.

[0145] A high number of such reactions include the formation of ethene C.sub.2H.sub.4 and acetylene C.sub.2H.sub.2 precursors. The formation of these precursors from methane leads to a separation of hydrogen and an increase in the gas volume. It is thus possible to reduce the formation of the carbon deposit precursors and thereby the formation of the carbon deposit itself by increasing the partial pressure of hydrogen in the reactor inlet gas, which means adding H.sub.2 to the gas mixture to be reformed, such as by adding H.sub.2 to the hydrocarbon containing gas and/or to the stream of syngas. For example, as shown on FIG. 4, increasing the amount of H.sub.2 in the gas mixture to be reformed from 10% to 40% leads to a significant decrease of the C.sub.2H.sub.4 concentration in the reforming plant, from about 0.35% to about 0% at 1225? C.

[0146] The first stream of syngas 126 exiting the second reforming plant 118 is fed to the blast furnace through gas inlets 138 disposed through the shaft inside the blast furnace 112 (i.e. the second stream of syngas 126 is fed through the shaft of the blast furnace) with a temperature of about 950? C. and a pressure of 1.5 to 4 barg.

[0147] Depending on the reforming process, the second stream of syngas may be cooled prior to being fed through the shaft of the blast furnace to a temperature of about 950? C.

[0148] The second stream of syngas 128 exiting the second reforming plant 122 is fed to the blast furnace through the tuyere 130 with a temperature of about 1200? C. and a pressure of 2 to 6 barg.

[0149] FIG. 3 illustrates a third embodiment of the present method for operating a blast furnace comprising the simultaneous injection of a first stream of syngas through the shaft of a blast furnace together with the injection of a cold hydrogen and/or a hydrocarbon containing gas and possibly also pulverized coal through the tuyere of the blast furnace.

[0150] Blast furnace gas 210 exiting the blast furnace 212 is collected at the top of a blast furnace 212.

[0151] The collected blast furnace gas 210 is generally pre-treated in a gas cleaning and cooling unit 214 upon exiting the blast furnace. Pre-treatment of the stream of blast furnace gas comprises first a cooling to reduce its vapor content, a cleaning, in particular a removing of dust and/or HCl and/or metal compounds.

[0152] Part of the cleaned blast furnace gas 219 is used as part of the fuel, along with humid air 223, and often along with other high calorific gases (not shown) in the burners of the cowper plant 221 for heating of the blast that is injected in the blast furnace at its tuyere level. Both, gases and air may be preheated or not.

[0153] Another part of the blast furnace gas 217 is used as part of the fuel, along with humid air 223, and often along with other high calorific gases (not shown) in the burners of the reforming plant 218. Both gases and air may be preheated or not.

[0154] Another stream 216 of the blast furnace gas is used within the reforming reaction. This stream is further fed to a compressor (pressuring unit) 215 for compressing the blast furnace gas to the required pressure level for reforming and injection in the blast furnace.

[0155] Remaining blast furnace gas exiting the blast furnace 212 and not being used in either the reforming plant or the cowper plant is referred to a blast furnace export gas 227 and is fed to other units within a steel plant comprising the blast furnace 212.

[0156] In the embodiment of FIG. 3, there is optionally also a hydrogenation and desulphurization unit 250 after the compressor (pressuring unit) 215.

[0157] Additionally, a stream 224 of coke oven gas and/or natural gas is fed to the reforming plants 218. The gas 224 can be desulphurized in the desulphurization unit 250. Desulphurization of the gas 224 can be performed along desulphurization of blast furnace gas (FIG. 3). Alternatively, the gas 224 can be desulphurized in a separate desulphurization unit (not shown). In such embodiments, hydrogen may be added to natural gas for the hydrogenation of organic sulphur contained in the natural gas (not shown).

[0158] Basic oxygen furnace gas and/or steam 225 might optionally be added to the stream of blast furnace gas (upstream and/or downstream of the pressuring unit 215), to the hydrogenation and desulphurization unit 250, to the stream of hydrocarbon containing gas 224 (not shown) and/or directly to a reforming plant 218 or after the reforming plant 224.

[0159] The reforming of the stream of blast furnace gas 216 along with the stream 224 of coke oven gas and/or natural gas is done in the reforming plant 218 to produce a stream of syngas 226. The two gas streams of blast furnace gas 216 and hydrocarbon containing gas need to be mixed prior entering the reforming plant 218, within the reforming plant 218 and/or prior to entering the hydrogenation and desulphurization plant 250.

[0160] The reforming processes are dry and/or wet reforming processes, possibly also in combination with a partial oxidation, leading to the formation of a stream of syngas 226, with high CO and H.sub.2 contents. Reforming processes occurs at pressure between 1.5 and 10 barg and depending on the reforming plant at a temperature above 900? C., preferably above 950? C., more preferably above 1000? C.

[0161] Blast furnace gas and/or hydrogen containing gas may optionally be heated prior to the reforming process (not shown). Heating might be performed e.g. by using tube bundle heat exchangers transferring part of the heat of the flue gas from the reforming plant. The same applies to the gas mixture comprising blast furnace gas and hydrocarbon containing gas entering the reforming plant, which will preferably also be heated to at least 350? C., more preferably to above 400? C. and preferred to above 450? C. Optionally, blast furnace gas and air used in the burners of the cowper plant and/or of the reforming plant may also be heated transferring part of the heat of the flue gas from the reforming plant in heat exchangers e.g. as tube bundle heat exchanger.

[0162] Additionally, the blast furnace installation comprises an electrolysis cell 232 fueled by electrical power 234 to produce a stream of H.sub.2 236 by electrolysis, preferably by water/steam electrolysis. The electrical power 234 fueling the electrolysis cell 232 is preferably renewable or green, i.e. obtained from a renewable source such as wind, solar and/or hydropower.

[0163] Alternatively or additionally, said hydrogen can be produced from natural gas through a pyrolysis process with solid carbon formation, or with combined Carbon Capture and Storage (CCS) technology and/or Carbon Capture and Utilization (CCU) technology. Hydrogen might also be produced by methane thermal cracking or steam methane reforming with combined CCS and/or CCU technology.

[0164] The stream of H.sub.2 236 produced by the electrolysis cell, or a part of it, is added to the stream 224 of coke oven gas and/or natural gas upstream of the reforming plant 218 to form a stream of H.sub.2-enriched hydrocarbon containing gas, which is fed to the reforming plant 218 and/or a part of it is fed to the stream of hydrocarbon containing gas prior to the hydrogenation step and/or is fed cold at the tuyere of the blast furnace on its own or together with other auxiliary fuels such as coal, natural gas, plastics, biomass and the like.

[0165] Basic oxygen furnace gas and/or steam might optionally be added to the stream of blast furnace gas (upstream and/or downstream of the pressuring unit 215 or the hydrogenation unit 250) (not shown) and/or the stream of hydrocarbon containing gas 224 (not shown) and/or to the stream of H.sub.2 236 (not shown) and/or directly to the reforming plant 218 or after the reforming plant 218.

[0166] Part of the stream of H.sub.2 236 may be added to the stream of syngas 226 downstream of the reforming plant 218 and upstream of gas inlets 238 disposed through the shaft inside the blast furnace 212. The stream of syngas 226 added with hydrogen 236 form a stream of H.sub.2-enriched gas 240, which is fed to the blast furnace through the gas inlets 238 at the shaft level, with a temperature of about 900? C. and a typical pressure of 1.5 to 4 barg.

[0167] Part of the Hydrogen 236 and/or hydrocarbon containing gas 224 may also be directly injected through the tuyere 230 of the blast furnace. In embodiments, injection of hydrogen 236 and/or hydrocarbon containing gas 224 may be performed along with injection of solid fuels, such as e.g. pulverized coal injection 229.

[0168] Part of the stream of H.sub.2 236 may be used as a coolant of the first stream of syngas 226. Using said hydrogen in this way, i.e. as a coolant, completely eliminates the need of heating said hydrogen prior to its injection through the shaft of the blast furnace 212 in an expensive heating device. Indeed, the excess heat of the syngas 226 heats said hydrogen. This allows to increase the efficiency of the process by eliminating both the need for syngas cooling and hydrogen heating.

[0169] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive, the disclosure is not limited to the disclosed embodiments. Other variations to be disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.