Reactor for gas-based pressurised counter current shaft furnace direct reduction

Abstract

The present application relates to a reactor (10) for gas-based pressurised counter current shaft furnace direct reduction, the reactor (10) comprising a reactor body (12) having the shape of a blast furnace reactor body, the reactor body including a side wall (14) forming a crucible-shaped hearth (16) at the bottom, a bosh (18) having an upwardly increasing diameter above the hearth (16), a belly (20) above the bosh (18) and a vertical shaft-shaped stack (22) having an upwardly decreasing diameter above the belly (20), and a gas guiding element (24) inside the reactor body (12). The gas guiding element (24) is configured to influence hot reducing gas distribution in the reactor body (12) by a) a shape of the gas guiding element (24) which is configured to form a gas flow distribution of gas introduced from the side wall (14) into the reactor (10) and / or b) comprising a plurality of hot reducing gas inlets (26) configured for injecting hot reducing gas into the reactor body (12).

Description

[0001] REACTOR FOR GAS-BASED PRESSURISED COUNTER CURRENT SHAFT FURNACE

[0002] DIRECT REDUCTION

[0003] TECHNICAL FIELD

[0004] The present invention relates to the field of liquid iron and green steel production by means of direct reduction of ores as an alternative process to traditional blast furnace processes, in particular by re-using an existing blast furnace reactor.

[0005] BACKGROUND

[0006] The demand of steel and liquid iron for many different applications, in particular in industry, continues on a high level. At the same time, in order to address climate change, finding ways of transforming industrial processes towards potentially carbon dioxide emission free production of steel and liquid iron is challenging, in particular cost intensive. However, if the demand of steel and liquid iron is to be satisfied also in the future whilst the carbon footprint of iron and steel producers is to be reduced, alternative processes to produce steel and liquid iron need to be applied.

[0007] Direct reduction of iron ore in the solid state is well known to the skilled person as a possible way to reduce or completely avoid carbon dioxide emissions during the production process. However, the spendings and investments necessary for a producer of steel and liquid iron to build such a direct reduction reactor are significant.

[0008] SUMMARY OF THE INVENTION

[0009] Following the above, the present invention aims at solving the problem of providing a way to make a transition from operating a blast furnace to operating a direct reduction reactor better affordable. The invention particularly solves the problem of how to re-use a blast furnace reactor as a direct reduction reactor .

[0010] The problem is preferably solved by a reactor according to Claim 1, a gas guiding element according to Claim 19, a method according to Claim 22, and a use according to Claim 30. Preferred features and embodiments of the invention are subject to the dependent claims.

[0011] According to an aspect of the invention, a reactor for gasbased pressurised counter current shaft furnace direct reduction comprises a reactor body having the shape of a blast furnace reactor body, the reactor body including a side wall forming a crucible-shaped hearth at the bottom, a bosh having an upwardly increasing diameter above the hearth, a belly above the bosh and a vertical shaft-shaped stack having an upwardly decreasing diameter above the belly, and a gas guiding element inside the reactor body. The gas guiding element can comprise a plurality of hot reducing gas inlets configured for injecting hot reducing gas into the reactor body. The hot reducing gas inlets are preferably distributed across the whole surface of the gas guiding element toward the portion of the reactor body containing the bulk material to be reduced when in use. In other words, the reactor body of the direct reduction reactor, in the following also named a DR-reactor, corresponds to the reactor body of a blast furnace reactor, in the following also named a BF-reactor, which has a shape that is not known to be used for direct reduction reactors . In contrast to a BF-reactor, the DR-reactor comprises the mentioned gas guiding element inside the reactor body which is necessary for ensuring an even and controlled distribution of reducing gases, namely, the hot reducing gas, inside the reactor body. The gas guiding element can be designed as an inset that balances the non-cylindric shape of the BF-reactor body to avoid non uniformity of the gas flow distribution. The gas guiding element can act by its shape and in addition or alternatively by the hot reducing gas inlets which can be designed to also influence the hot reducing gas distribution. Ideally, the hot reducing gas inlets - if provided - are individually controllable so that the amount of hot reducing gas, its speed, temperature, and other properties can be individually set for each of the hot reducing gas inlets. Less preferred, but also possible, is a configuration in which the hot reducing gas inlets - if provided - are grouped and groups of inlets are controllable. It is generally also possible for the DR-reactor to work without an individual or group-wise control of the hot reducing gas inlets. The gas guiding element can advantageously also be configured to act as a material splitter and to increase the voidage in a central part of the reactor body involving more reducing gas in the central part of the reactor body .

[0012] Thus, the gas guiding element is configured to influence hot reducing gas distribution in the reactor body. Influencing the hot reducing gas distribution in the reactor body can be carried out by a shape of the gas guiding element which is configured to form a gas flow distribution of gas introduced from the side wall into the reactor. Additionally or alternatively the gas guiding element comprises a plurality of hot reducing gas inlets configured for injecting hot reducing gas into the reactor body.

[0013] This reactor allows re-using an existing BF-reactor as a DR- reactor which allows the steel or iron producer to switch over to direct reduction processes, in particular gas-based counter current shaft furnace direct reduction processes without melting inside the reactor body and outlet of direct reduced iron pellets, in particular hot direct reduced iron pellets, in the following also named HDRI-pellets , and / or lump ore at a considerably lower cost if compared to building a new direct reduction reactor. Hence, capital expenditures can be significantly reduced which ultimately increases the industry's power and ability to adapt to alternative processes to reduce and even avoid carbon dioxide emissions of that industry sector. All reactants and chemical direct reduction reactions are already known and occur in existing blast furnace processes .

[0014] In a preferred reactor, the gas guiding element is configured to be optionally arranged in the reactor body, which is according to the invention an obvious measure as this optional arrangement offers the possibility to re-use an existing BF- reactor as a DR-reactor which allows the steel or iron producer to switch over to direct reduction processes.

[0015] In a preferred reactor, the gas guiding element has an outer surface having a surface normal which encloses an angle of more than 0° and less than 90° with a longitudinal axis of the reactor body. This way, the gas guiding element can very well influence the gas distribution. In a preferred reactor, the gas guiding element is a false bottom, which may comprise the hot reducing gas inlets, if the gas guiding element is equipped with such inlets. A false bottom is, in the context of the present invention, an insert that is added to the bottom of the reactor body. The false bottom can modify the bottom of the reactor body. If the gas guiding element is configured for injecting hot reducing gas into the reactor body, this facilitates the feeding of hot reducing gases into the reactor body. The hot reducing gas can be delivered to the false bottom via existing tapping holes of the BF-reactor. However, also other means of providing hot reducing gas to the inside of the reactor body are possible.

[0016] It may be envisaged that the gas guiding element can be formed from the material to be used inside the reactor body and which is to be used in the hot direct reduction process. In particular, the gas guiding element may be formed by the iron pellets and / or the lump ore, which can be compacted by its own weight at the bottom of the reactor. Some of the compacted material, especially in the form of the pellets and / or the lump ore, can remain in the reactor body, whereby further compaction and / or growth of the compacted material takes place. In this way, a gas guide element can be formed. Preferably, however, the gas guiding element is formed from a separate material. In particular, the gas guiding element preferably is an element separate, or separable, from both the reactor body and the material to be used inside the reactor body.

[0017] Preferably, the gas guiding element is cone shaped or mushroom shaped having a vertical extension. The gas guiding element, if cone shaped, can have a single cone angle or several subsequent cone angles so that a multiangle cone can be provided. This way, the cone shaped, or mushroom shaped, gas guiding element can preferably adapt the inside volume of the reactor body to the outside shape of the reactor body to avoid turbulences inside the reactor body. In other words, at a height where the outside shape of the reactor body is conically shaped, the gas guiding element can be shaped in parallel so that the distance between the gas guiding element and the outside shape of the reactor body can be constant along the vertical extension of the reactor body to avoid pressure changes in the vertical gas flow .

[0018] Advantageously, the gas guiding element is installed in the hearth of the reactor body. This way, the gas guiding element can easily be reached from the bottom to facilitate the feeding of hot reducing gas to the inside of the reactor body whilst maximising the volume of the reactor body available for the reaction. However, the gas guiding element can also be installed in the bosh, belly and stack. In any installation, the gas guiding element can be configured to also act as a material splitter, increasing voidage of the material column above and involving more gas in a central part of the reactor body further improving uniformity of the gas distribution.

[0019] Preferably, the gas guiding element extends inside the bosh, the belly and / or the stack. According to a preferred configuration, the gas guiding element extends inside the bosh or inside the bosh and the belly or inside the bosh and the belly and the stack. This way, the gas guiding element can very well influence the internal dimensions of the reactor body along the bosh, the belly and / or the stack. Particularly preferably, the gas guiding element is installed in the hearth and extends to at least the bosh, or the bosh and the belly, or the bosh, belly and stack.

[0020] Preferably, the reactor comprises tuyeres, in particular peripheral tuyeres, which are installed to the reactor body, wherein the tuyeres are configured for injecting hot reducing gas into the reactor body. Such tuyeres are normally present in a BF-reactor to add hot air to the reaction zone inside of the reactor body. Hence, the shell of a BF-reactor body normally has openings for these tuyeres. It is advantageous to make use of the tuyeres to inject reducing gas in addition to the reducing gas injected via the gas inlets of the gas guiding element. By injecting reducing gas through the tuyeres, in particular through the peripheral tuyeres, the flow of the gas stream can be influenced so that an improved distribution of reducing gas within the reactor body can be achieved. Hence, an improved efficiency of the DR-reactor can be achieved.

[0021] Existing tuyeres of a BF-reactor can be used, preferably after a modification, wherein only a portion of the existing tuyeres, all of the existing tuyeres or none of the existing tuyeres, if any, can preferably be used. Of course, the additional injection of reducing gas is only optional and not essential for the invention.

[0022] Alternatively, reducing gases can be injected via existing cooling elements in the BF-reactor body if these cooling elements are removed and the resulting openings are used to inject additional reducing gas. As a further alternative, additional openings can be machined into the BF-reactor body to inject additional reducing gas so that the distribution of reducing gas can be further influenced.

[0023] Preferably, the tuyeres have various diameter, inclination, and protrusion. Such variation of the tuyeres allows for further optimising the influence of injected reducing gas on the flow of reducing gas within the reactor body. However, also tuyeres having all the same diameter, inclination and protrusion are possible . In a preferred embodiment, the hearth of the reactor body comprises lateral openings which are configured to discharge HDRI-pellets and / or lump ore from the reactor body. Preferably these openings are where some of the tuyeres of a BF-reactor used to be. In other words, in this preferred embodiment, at least some of the tuyeres of the former BF-reactor are removed leaving the lateral openings which are configured to discharge HDRI-pellets and / or lump ore from the reactor body. It is preferably possible that some other of the tuyeres are used for injecting reducing gas.

[0024] According to the description, the term "HDRI-pellets and / or lump ore" encompasses any solid used in the hot direct reduction process, especially the product resulting from the HDRI , in particular the sponge iron. In any case the lateral openings of the reactor body can be configured to facilitate discharging or removing any solid material from the reactor body. The solid material can particularly be in the form of lumps, pellets, or fines.

[0025] Further preferably, the lateral openings are provided in the side wall each having a chamfer on an inner part of the side wall to increase an opening diameter, wherein preferably the chamfer is only formed in a refractory lining of the side wall. In this way, the lateral openings are particularly well configured to discharge HDRI-pellets and / or lump ore, in particular to facilitate the discharge of the HDRI-pellets and / or the lump ore. The chamfer is preferably formed towards the upper part of the reactor body to facilitate the discharge of the HDRI-pellets and / or the lump ore. Whilst it is preferable to form the chamfer only in the refractory lining of the side wall which is normally present in a BF-reactor, it is also possible, although less preferred, to cut into the metallic shell of the BF-reactor body. Alternatively, the lateral openings are provided without a chamfer, and it is of course possible to discharge HDRI-pellets and / or lump ore otherwise from the reactor body, as is explained further below.

[0026] Preferably, the reactor comprises a discharge system, in particular comprising one or more screw conveyors or one or more push rods, which discharge system is preferably provided in the bosh and / or the belly of the reactor body, which discharge system is configured to discharge HDRI-pellets and / or lump ore through some, preferably four, or all of the lateral openings. The discharge system can also be provided in the stack of the reactor body. The screw conveyors are preferably water cooled.

[0027] Preferably, the reactor comprises a bottom opening at the bottom of the reactor body, wherein the reactor comprises a central HDRI-pellet, and / or lump ore, discharge system inside the reactor body configured to discharge HDRI-pellets and / or lump ore through the bottom opening. As the HDRI-pellet, and / or lump ore, discharge system, a screw conveyor, which can preferably be water-cooled, may be used. The bottom opening can be provided by a tapping hole at the bottom of the reactor body, or by a dedicated discharge opening. Further preferably, a material handling system is provided to further convey the HDRI-pellets, and / or the lump ore, out of and away from the opening .

[0028] A central HDRI-pellet, and / or lump ore, discharge system is advantageous as a single discharge system is capable of reliably discharging material, and it may allow for more accurately controlling the discharge of HDRI-pellets and / or lump ore. On the other hand, an internal discharge system having rotating equipment needs to be installed inside the reactor body in a very challenging environment where it is not possible to access this area for maintenance during operation which is why a system without a central HDRI-pellet, and / or lump ore, discharge system is also advantageous.

[0029] The reactor can comprise a burden feeder inside the reactor body, wherein the burden feeder is configured to regulate a flow of HDRI-pellets and / or lump ore inside the reactor body. Such burden feeder can preferably have a cylindrical or a conical shape. The burden feeder can assist in discharging the HDRI-pellets and / or the lump ore out of the reactor body in that it very reliably resolves possible blocking constellations of the HDRI-pellets and / or the lump ore inside of the reactor body. As an alternative, it is not necessary for the reactor to comprise a burden feeder inside the reactor body.

[0030] Preferably, the reactor further comprises a rotating device, in particular a rotary valve or a screw feeder, outside of the reactor body, wherein the rotating device is configured to regulate a flow of HDRI-pellets and / or lump ore out of the reactor body. Such a rotating device outside of the reactor body is better accessible from the outside than an element inside of the reactor body. It can be configured to drive and to stop the flow of HDRI-pellets and / or lump ore out of the reactor body. In a preferred embodiment, the rotating device is cooled by water. However, it is also possible to regulate the flow of HDRI-pellets and / or lump ore out of the reactor body by other means .

[0031] Preferably, the reactor further comprises a cooling zone for HDRI-pellets and / or lump ore below the hot reducing gas inlets. Providing the cooling zone below the hot reducing gas inlets facilitates the cooling of the HDRI-pellets and / or the lump ore. The cooling zone can also facilitate a carburization process of the HDRI-pellets and / or the lump ore.

[0032] The cooling zone can be located outside the reactor body. A lock hopper can be helpful in this context to lock the HDRI- pellets and / or the lump ore out of the pressurised DR-reactor. The cooling zone can also be located inside the reactor body. The cooling zone can then be located between burden feeders and the outlet of the HDRI-pellets and / or the lump ore, for example tuyere holes, and the HDRI-pellets and / or the lump ore can be locked out of the pressurised DR-reactor via a lock hopper.

[0033] A gas guiding element for a reactor as described herein can comprise a plurality of hot reducing gas inlets configured for injecting hot reducing gas into the reactor body. Preferably, the gas inlets are individually controllable or group-wise controllable in order to control the flow of hot reducing gas inside the reactor more accurately, if compared to a configuration where the gas inlets are not individually controlled .

[0034] The gas guiding element allows re-using an existing BF-reactor as a DR-reactor which allows the steel or iron producer to switch over to direct reduction processes, in particular gasbased counter current shaft furnace direct reduction processes without melting inside the reactor body and outlet of HDRI- pellets and / or lump ore at a considerably lower cost if compared to building a new direct reduction reactor. Hence, capital expenditures can be significantly reduced which ultimately increases the industry's power and ability to adapt to alternative processes to reduce and even avoid carbon dioxide emissions of that industry sector. A preferred gas guiding element is a false bottom, which may comprise hot reducing gas inlets. A false bottom is, in the context of the present invention, an insert that can be added to the bottom of a reactor body. The false bottom can modify the bottom of the reactor body.

[0035] The gas guiding element is cone shaped or mushroom shaped having a vertical extension. The gas guiding element, if cone shaped, can have a single cone angle or several subsequent cone angles so that a multiangle cone can be provided. This way, the cone shaped, or mushroom shaped, gas guiding element can preferably adapt the inside volume of the reactor body to the outside shape of the reactor body to avoid turbulences inside the reactor body. In other words, at a height where the outside shape of the reactor body is conically shaped, the gas guiding element can be shaped in parallel so that the distance between the gas guiding element and the outside shape of the reactor body can be constant along the vertical extension of the reactor body to avoid pressure changes in the vertical gas flow .

[0036] A preferred gas guiding element is configured to be installed in the hearth of the reactor body. This way, the gas guiding element can easily be reached from the bottom to facilitate the feeding of hot reducing gas to the inside of the reactor body whilst maximising the volume of the reactor body available for the reaction. However, the gas guiding element can also be configured to be installed in the bosh, belly and stack.

[0037] According to an aspect of the invention, a method of re-using a blast furnace reactor includes the steps of using a blast furnace reactor body including a side wall forming a crucibleshaped hearth at the bottom, a bosh having an upwardly increasing diameter above the hearth, a belly above the bosh and a vertical shaft-shaped stack having an upwardly decreasing diameter above the belly as a reactor body, and installing a gas guiding element inside the reactor body, to thereby prepare the blast furnace reactor for a gas-based pressurised counter current shaft furnace direct reduction process.

[0038] In other words, the reactor body of the DR-reactor is obtained from the reactor body of a BF-reactor, although a BF-reactor has a shape that is not known to be used for DR-reactors. In contrast to a BF-reactor, the DR-reactor comprises the mentioned gas guiding element inside the reactor body which is necessary for ensuring an even and controlled distribution of reducing gases, namely, the hot reducing gas, inside the reactor body. The gas guiding element can be designed as an inset that balances the non-cylindric shape of the BF-reactor body to avoid turbulences in the gas flow. The gas guiding element can act by its shape and in addition or alternatively by the hot reducing gas inlets which can be designed to also influence the hot reducing gas distribution. Ideally, the hot reducing gas inlets are individually controllable so that the amount of hot reducing gas, its speed, and other properties can be individually set for each of the hot reducing gas inlets. Less preferred, but also possible, is a configuration in which the hot reducing gas inlets are grouped and groups of inlets are controllable. It is generally also possible for the DR- reactor to work without an individual or group-wise control of the hot reducing gas inlets.

[0039] Re-using an existing BF-reactor as a DR-reactor allows the steel or iron producer to switch over to direct reduction processes, in particular gas-based counter current shaft furnace direct reduction processes without melting inside the reactor body and outlet of HDRI-pellets and / or lump ore at a considerably lower cost if compared to building a new DR- reactor. Hence, capital expenditures can be significantly reduced which ultimately increases the industry' s power and ability to adapt to alternative processes to reduce and even avoid carbon dioxide emissions of that industry sector.

[0040] Direct reduced iron pellets have properties similar to current processes, carburization levels and reducing gas species, compared to e.g. the MIDREX or HYL process, such that the HDRI- pellets can be used in an electric smelting furnace melting unit as known from a Continuous Reduced Steelmaking Process, a typical Electric Arc Furnace or in a smelter downstream which further strengthens the effect of the invention.

[0041] Preferably, the HDRI-pellets and / or lump ore cool down in a cooling zone. The cooling zone can also facilitate a carburization process of the HDRI-pellets and / or lump ore.

[0042] Preferably, the step of installing the gas guiding element is carried out so that the gas guiding element is installed in the hearth of the reactor body. This way, the gas guiding element can easily be installed as the hearth is more easily accessible if compared to other portions of the reactor body. Further, as explained also above, the gas guiding element can easily be reached from the bottom to facilitate the feeding of hot reducing gas to the inside of the reactor body whilst maximising the volume of the reactor body available for the reaction. However, the gas guiding element can also be installed in the bosh, belly and stack.

[0043] The blast furnace reactor can comprise a charging system for feeding ores, wherein the charging system can have a rotating chute which allows to charge the iron ore feed specifically to areas at the DR reactor's top. This measure allows to compensate partly possible inhomogeneities regarding the descend and residence time of the iron ore feed.

[0044] According to a preferred method, the chute is extended to reduce a falling height of the ores, e.g. pellets, to be fed to the reactor body during the direct reduction process. This way, it is possible to limit the falling height of the ores, in particular pellets. Further, it is additionally or alternatively possible to install a distributor with pipes so that the ores can be led to the bulk ore surface in the reactor body to minimise the falling height. For example, pellets or ores can be discharged from the chute to an internal ring type hopper equipped with charging legs. However, it is also possible to not modify the chute or install a distributor inside the reactor body.

[0045] Preferably, the blast furnace reactor comprises a charging system for feeding ores, in particular according, but not limited to, the above described, wherein the charging system, according to a preferred method, is tightened to avoid leaking of gas through the charging system. This is particularly advantageous, if pure hydrogen is used as reducing gas because hydrogen is hard to contain within a vessel. Here, leak tightening the charging system, in particular a bell less top or two bell top, but also other charging systems, allows for an improved safety of operating the DR-reactor and avoids waste of reducing gas .

[0046] Potential countermeasures against leaking of gas, in particular hydrogen, can be taken, for example, by the use of hydrogen proof high temperature gaskets, inertisation or installation of leak gas removal systems. Preferably, the blast furnace reactor comprises tuyeres installed at its side wall, wherein at least some of the tuyeres are, according to a preferred method, de-installed, thereby leaving lateral openings in the side wall which are configured to discharge hot direct reduced iron pellets and / or lump ore from the reactor body. In some BF-reactors, the tuyeres can be of various diameter, inclination and protrusion. This way, it is possible to make use of the existing openings in the side wall of the BF-reactor for a new use of discharging HDRI-pellets and / or lump ore from the BF-reactor.

[0047] Optionally, the lateral openings are modified to each having a chamfer on an inner part of the side wall to increase an opening diameter, wherein preferably the chamfer is only formed in a refractory lining of the side wall. According to this preferred feature of the method, the metallic part of the BF- reactor body does not have to be modified. This is advantageous in particular because the metallic part acts as a pressure vessel to contain the reaction and is not weakened by any new openings. However, it is also possible to modify the metallic part of the BF-reactor body.

[0048] Preferably, the blast furnace reactor comprises tuyeres installed at its side wall, wherein, according to the preferred method, at least some of the tuyeres are tightly connected to a reducing gas feed line so that they are configured for injecting hot reducing gas into the reactor body.

[0049] According to a preferred method, the blast furnace reactor comprises a tapping hole at the bottom of the blast furnace reactor body, wherein the method comprises installing inside the reactor body a central HDRI-pellet and / or lump ore discharge system configured to discharge HDRI-pellets and / or lump ore through the tapping hole. According to an aspect of the invention, a use of a reactor having a blast furnace reactor body is provided. A gas guiding element is used and inserted into the blast furnace reactor body to use the blast furnace reactor body and the inserted gas guiding element in a gas-based pressurised counter current shaft furnace direct reduction.

[0050] In other words, the DR-reactor facility is obtained from a BF- reactor facility.

[0051] Re-using an existing BF-reactor as a DR-reactor allows the steel or iron producer to switch over to gas-based counter current shaft furnace direct reduction processes without melting inside the reactor body and outlet of HDRI-pellets and / or lump ore at a considerably lower cost if compared to building a new DR-reactor. Hence, capital expenditures can be significantly reduced which ultimately increases the industry's power and ability to adapt to alternative processes to reduce and even avoid carbon dioxide emissions of that industry sector .

[0052] In summary, a BF-reactor can be used as a DR-reactor whereby iron oxide feed sinks top-down and hot reducing gases flow bottom-up. All grades of iron ore pellets can be processed in this direct reduction process. The direct reduction process can be operated with common reducing gases comprising predominantly hydrogen, H2, and carbon monoxide, CO, based, for example, on natural gas or coke oven gas after a reforming step or based on pure, preferably green hydrogen, i.e. hydrogen obtained from regenerative energy sources such as solar and wind energy, avoiding carbon dioxide emissions and decarbonizing the process. All reactants and chemical direct reduction reactions are known and occur in existing blast furnace processes. The direct reduction process can produce solid state, preferably green, sponge iron. Following the present invention, many parts of an existing BF-reactor can be reused for serving the direct reduction process. The produced HDRI-pellets and / or lump ore can be shifted out of the BF-reactor body via existing but modified tuyere holes. The HDRI-pellets and / or lump ore can be further processed, for example in an electric smelting furnace melting unit as known from a Continuous Reduced Steelmaking Process, an electric arc furnace or in a hot briquetting facility with a respective HDRI-pellet and / or lump ore cooling system.

[0053] All grades of iron ore pellets, lump ore and sinter can be processed in a direct reduction process carried out in a reactor according to the present invention. It is expected that the existing burdening and charging system of the blast furnace can be used without any major adjustments.

[0054] Further advantages of the invention can be derived from the whole set of claims as well as the following description of the figures and preferred embodiments.

[0055] BRIEF DESCRIPTION OF THE FIGURES

[0056] Fig. 1 illustrates a preferred embodiment of a reactor for gas-based pressurised counter current shaft furnace direct reduction.

[0057] Fig. 1A is an enlarged illustration of hot reducing gas inlets . Fig. 2 illustrates another preferred embodiment of a reactor for gas-based pressurised counter current shaft furnace direct reduction.

[0058] Fig. 2A is an enlarged illustration of hot reducing gas inlets .

[0059] Fig. 3 illustrates another preferred embodiment of a reactor for gas-based pressurised counter current shaft furnace direct reduction.

[0060] Fig. 3A is an enlarged illustration of hot reducing gas inlets .

[0061] Fig. 4 illustrates another preferred embodiment of a reactor for gas-based pressurised counter current shaft furnace direct reduction.

[0062] Fig. 4A is an enlarged illustration of hot reducing gas inlets .

[0063] Fig. 5 illustrates another preferred embodiment of a reactor for gas-based pressurised counter current shaft furnace direct reduction.

[0064] Fig. 5A is an enlarged illustration of hot reducing gas inlets .

[0065] Fig. 6 illustrates another preferred embodiment of a reactor for gas-based pressurised counter current shaft furnace direct reduction.

[0066] Fig. 6A is an enlarged illustration of hot reducing gas inlets . DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0067] In the embodiments described in the following, same or corresponding elements are assigned same reference signs and a repetitive description of these elements is generally omitted.

[0068] Figure 1 illustrates a preferred embodiment of a reactor 10 for gas-based pressurised counter current shaft furnace direct reduction. The reactor 10 comprises a reactor body 12 which has the shape of a BF-reactor. This embodiment relates to a re-use of a BF-reactor so that the reactor body 12 used to be a BF- reactor body. The reactor body 12 comprises a side wall 14 comprising a metallic shell 33 and a refractory lining 32 inside of the metallic shell 33. The side wall 14 forms a hearth 16 having the shape of a crucible at the bottom. Above and adjacent the hearth 16, the side wall 14 forms a bosh 18 which has an upwardly increasing diameter starting from the diameter of the hearth 16 and increasing with increasing height. Above and adjacent the bosh 18, the side wall 14 forms a belly 20 which is cylindrically formed. In other words, the belly 20 has the same diameter along its vertical extension. The diameter of the belly 20 is the largest diameter of the bosh 18. Above and adjacent the belly 20, the side wall 14 forms a vertical shaft-shaped stack 22 having an upwardly decreasing diameter.

[0069] The fact that a BF-reactor body is not cylindrically shaped but comprises inter alia the bosh and the stack both of which have a conical shape which means that their diameters change along the vertical extension of the reactor body makes a BF-reactor body in its original configuration less suitable for a DR reaction because the reliability of a DR reaction depends also on the uniformity of the flow of reducing gas, and the pellets, within the reactor body 12.

[0070] Inside of the reactor body 12, the reactor 10 contains bulk iron ore pellets 50 which, after having undergone the direct reduction reaction, result in HDRI-pellets 52 to be discharged from the reactor 10. The iron ore pellets 50 are fed into the reactor 10 from the top and discharged at the bottom, whilst the hot reducing gases flow from the bottom towards the top of the reactor 10.

[0071] In order to increase the uniformity of the flow of reducing gas, the embodiment of Fig. 1 comprises a gas guiding element 24 at the bottom of the reactor body 12 which comprises a plurality of hot reducing gas inlets 26 which in this embodiment are evenly distributed over the gas guiding element 24 and are configured for injecting hot reducing gas into the reactor body 12. The gas guiding element 24 is mounted in the hearth 16 of the reactor body and extends upwardly into the bosh 18 and belly 20. The gas guiding element 24 has a conical shape which serves uniformity of the reducing gases, and pellets, within the reactor body 12 otherwise resulting from the shape of the side wall 14.

[0072] Fig. 1A is an enlarged illustration of hot reducing gas inlets 26 designed to allow a certain distribution of the reducing gases e.g. ceramic throttles as an example of enabling the hot reducing gas inlets 26 to provide a uniform flow of reducing gases .

[0073] In Fig. 1, a reducing gas feed line 54 is provided to feed reducing gas through a valve and a tapping hole 56 towards the inside of the hearth 16 and from there through the hot reducing gas inlets 26 of the gas guiding element 24 to the inside of the reactor body 12. The reducing gas feed line 54 has a branch which feeds hot reducing gas to the gas guiding element 24 and another branch which, through another valve, feeds hot reducing gas to a tuyere 28 installed to the reactor body 12 and being configured for injecting hot reducing gas into the reactor body .

[0074] The tuyere 28 is preferably a re-used or modified tuyere of the BF-reactor. By the tuyere 28, it is possible to additionally influence and thus control the flow of hot reducing gas in the inside of the reactor body 12. Fig. 1 schematically illustrates one tuyere 28, but the embodiment comprises a plurality of tuyeres 28 distributed along the circumference of the reactor body 12.

[0075] Some of the tuyeres of the BF-reactor are re-used differently, namely, they are demounted leaving a lateral opening 30 in the side wall 14 for discharging the HDRI-pellets 52. The lateral openings 30 can be kept in the form that is left over from the removed tuyere of the BF-reactor, but it is preferred for the lateral opening 30 to be modified to comprise a chamfer 34 in the refractory lining 32 of the side wall 14, leaving the metallic shell 33 of the reactor body 12 preferably intact. Providing the chamfer 34 only in the refractory lining 32 of the side wall 14 allows the chamfer 34 to have the desired effect as further described below, whilst maintaining the metallic shell 33 unaffected improves the stability of the reactor body 12 which effectively is a pressure vessel during use so that stability and particularly tightness to reducing gases is important. The chamfer 34 facilitates discharging of the HDRI-pellets 52 from the reactor body 12 through the lateral openings 30 because it frees the way for the HDRI- pellets from the top and inside of the reactor body 12 towards the outside. Downstream of the lateral openings 30, the discharge flow of HDRI-pellets 52 can be controlled preferably by a rotary valve 42. The HDRI-pellets 52 enter a cooling zone 44 where heat is transferred via a cooling gas entering the cooling zone 44 through a cooling gas inlet line 43 and leaving the cooling zone 44 through a cooling gas outlet line 45.

[0076] Fig. 1 further schematically illustrates a chute charging system 46 and, as an alternative, a double bell charging system 48, as a further potential alternative a distribution pipe 47 and an internal ring type hopper equipped with charging legs 49 are illustrated, all of which are potentially installed at the top of the reactor body 12 to feed iron ore pellets 50 or other forms of iron ore or material to be reduced in the DR-reactor from the top. In order to limit the height the material falls down from the chute charging system 46 or the double bell charging system 48 onto the bulk iron ore pellets 52 or material inside of the reactor body 12, it is intended to provide an extension of the chute or an additional chute or other means to better control how the iron ore or material to be reduced is fed to the reactor body 12.

[0077] Fig. 2 illustrates another preferred embodiment of a reactor 10 for gas-based pressurised counter current shaft furnace direct reduction. A screw conveyor 60 is provided as an embodiment of a discharge system 36 to discharge HDRI-pellets in a controlled way through the lateral opening 30.

[0078] Fig. 3 illustrates yet another preferred embodiment of a reactor 10 for gas-based pressurised counter current shaft furnace direct reduction. Instead of a screw conveyor 60 as illustrated in Fig. 2, this embodiment comprises a push rod 62 as an embodiment of the discharge system 36. The push rod 62 is configured to push HDRI-pellets out of the reactor body 12 through the lateral opening 30 in a reciprocating manner.

[0079] Fig. 4 illustrates a further preferred embodiment of a reactor 10 for gas-based pressurised counter current shaft furnace direct reduction. In this embodiment, a burden feeder 40 within the reactor body 12 is provided to control and to help the pellet flow through the reactor towards the discharge. In the embodiment of Fig. 4, the burden feeder 40 is located at the height of the belly 20 of the reactor body 12.

[0080] Further, the gas guiding element 24 is modified with respect to the embodiments of Figs. 1-3 taking the burden feeder 40 into account .

[0081] At the height of the bosh 18, the gas guiding element 24 comprises cooling gas inlet lines 43 and cooling gas outlet lines 45.

[0082] Fig. 5 illustrates a further preferred embodiment of a reactor 10 for gas-based pressurised counter current shaft furnace direct reduction. As an alternative to the embodiments of Figs. 1-4, this embodiment provides a central discharge system 58 comprising the gas guiding element 24 of the embodiment according to Fig. 5 which is funnel-shaped rather than cone- shaped. The hot reducing gas inlets 26 of the gas guiding element 24 are evenly distributed over the surface of the gas guiding element 24. The funnel shape of the gas guiding element 24 guides the HDRI-pellets towards a central bottom opening 38 from which a screw conveyor 60 as a discharge system 36 conveys the HDRI-pellets through a tapping hole 56 to the cooling zone 44 outside of the reactor body 12. Fig . 6 illustrates a further preferred embodiment of a reactor

[0083] 10 for gas-based pressurised counter current shaft furnace direct reduction. As an alternative to the embodiments of Figs.

[0084] 1-5, this embodiment provides a gas guiding element 24 having no hot reducing gas inlets 26.

[0085] LIST OF REFERENCE NUMERALS

[0086] 10 reactor

[0087] 12 reactor body

[0088] 14 side wall

[0089] 16 hearth

[0090] 18 bosh

[0091] 20 belly

[0092] 22 stack

[0093] 24 gas guiding element

[0094] 26 hot reducing gas inlet

[0095] 28 tuyere

[0096] 30 lateral opening

[0097] 32 refractory lining

[0098] 33 metallic shell

[0099] 34 chamfer

[0100] 36 discharge system

[0101] 38 bottom opening

[0102] 40 burden feeder

[0103] 42 rotary valve

[0104] 43 cooling gas inlet line

[0105] 44 cooling zone

[0106] 45 cooling gas outlet line

[0107] 46 chute charging system

[0108] 47 distribution pipe

[0109] 48 double bell charging system

[0110] 49 ring type hopper with charging legs

[0111] 50 iron ore pellets HDRI-pellets reducing gas feed line tapping hole central HDRI-pellet discharge system screw conveyor push rod

Claims

ClaimsReactor (10) for gas-based pressurised counter current shaft furnace direct reduction, the reactor (10) comprising a reactor body (12) having the shape of a blast furnace reactor body, the reactor body including a side wall (14) forming a crucible-shaped hearth (16) at the bottom, a bosh (18) having an upwardly increasing diameter above the hearth (16) , a belly (20) above the bosh (18) and a vertical shaft-shaped stack (22) having an upwardly decreasing diameter above the belly (20) , and a gas guiding element (24) inside the reactor body (12) , wherein the gas guiding element (24) is configured to influence hot reducing gas distribution in the reactor body (12) by a) a shape of the gas guiding element (24) which is configured to form a gas flow distribution of gas introduced from the side wall (14) into the reactor (10) and / or b) comprising a plurality of hot reducing gas inlets (26) configured for injecting hot reducing gas into the reactor body ( 12 ) .

2. Reactor (10) according to Claim 1, wherein the gas guiding element (24) is configured to be optionally arranged in the reactor body (12) .

3. Reactor (10) according to Claim 1 or 2, wherein the gas guiding element (24) has an outer surface having a surface normal which encloses an angle of more than 0° and less than 90° with a longitudinal axis of the reactor body(10) .

4. Reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) is a false bottom.

5. Reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) is cone shaped or mushroom shaped having a vertical extension.

6. Reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) is installed in the hearth (16) of the reactor body (12) .

7. Reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) extends inside the bosh ( 18 ) .

8. Reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) extends inside the belly (20) .

9. Reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) extends inside the stack ( 22 ) .

10. Reactor (10) according to any of the preceding claims, the reactor (10) comprising tuyeres (28) which are installed to the reactor body (12) ,wherein the tuyeres (12) are configured for injecting hot reducing gas into the reactor body (12) .

11. Reactor (10) according to any of the preceding claims, wherein the hearth (16) of the reactor body (12) comprises lateral openings (30) which are configured to discharge hot direct reduced iron pellets from the reactor body(12) .

12. Reactor (10) according to Claim 11, wherein the lateral openings (30) are provided in the side wall (14) each having a chamfer (34) on an inner part of the side wall (14) to increase an opening diameter, wherein preferably the chamfer (34) is only formed in a refractory lining (32) of the side wall (14) .

13. Reactor (10) according to Claim 11 or 12, further comprising a discharge system (36) , in particular comprising one or more screw conveyors (60) , which discharge system (36) is preferably provided in the bosh (18) and / or the belly (20) of the reactor body (12) , which discharge system (36) is configured to discharge hot direct reduced iron pellets (52) through some or all of the lateral openings (30) .

14. Reactor (10) according to any of the preceding claims, wherein the reactor (10) comprises a bottom opening (38) at the bottom of the reactor body (12) , wherein the reactor (10) comprises a central hot direct reduced iron pellet discharge system (58) inside the reactor body (12) configured to discharge hot directreduced iron pellets (52) through the bottom opening (38) .

15. Reactor (10) according to any of the preceding claims, wherein the reactor (10) comprises a burden feeder (40) inside the reactor body, wherein the burden feeder (40) is configured to regulate a flow of hot direct reduced iron pellets (52) inside the reactor body (12) .

16. Reactor (10) according to any of the preceding claims, wherein the reactor (10) further comprises a rotating device (42) outside of the reactor body (12) , wherein the rotating device is configured to regulate a flow of hot direct reduced iron pellets (52) out of the reactor body (12) .

17. Reactor (10) according to Claim 16, wherein the rotating device is a rotary valve (42) or a screw feeder.

18. Reactor (10) according to any of the preceding claims, further comprising a cooling zone (44) for hot direct reduced iron pellets (52) below the hot reducing gas inlets (26) .

19. Gas guiding element (24) for a reactor (10) according to any of the preceding claims, wherein the gas guiding element (24) is cone shaped or mushroom shaped having a vertical extension.

20. Gas guiding element (24) according to Claim 19, wherein the gas guiding element (24) is a false bottom.

21. Gas guiding element (24) according to Claim 19 or 20, wherein the gas guiding element (24) is configured to be installed in the hearth (16) of the reactor body (12) .

22. Method of re-using a blast furnace reactor including the steps of using a blast furnace reactor body including a side wall (14) forming a crucible-shaped hearth (16) at the bottom, a bosh (18) having an upwardly increasing diameter above the hearth (16) , a belly (20) above the bosh (18) and a vertical shaft-shaped stack (22) having an upwardly decreasing diameter above the belly (20) as a reactor body (12) , and installing a gas guiding element (24) inside the reactor body ( 12 ) , to thereby prepare the blast furnace reactor for a gasbased pressurised counter current shaft furnace direct reduction process.

23. Method according to Claim 22, wherein the step of installing the gas guiding element (24) is carried out so that the gas guiding element (24) is installed in the hearth (16) of the reactor body (12) .

24. Method according to Claim 22 or 23, wherein the blast furnace reactor comprises a charging system (46, 48) for feeding ores, the charging system (46, 48) having a chute,wherein the chute is extended to reduce a falling height of the ores to be fed to the reactor body (12) during the direct reduction process.

25. Method according to any of Claims 22-24, wherein the blast furnace reactor comprises a charging system (46, 48) for feeding ores, wherein the charging system (46, 48) is tightened to avoid leaking of gas through the charging system (46, 48) .

26. Method according to any of Claims 22-25, wherein the blast furnace reactor comprises tuyeres installed at its side wall (14) , wherein at least some of the tuyeres are de-installed, thereby leaving lateral openings (30) in the side wall (14) which are configured to discharge hot direct reduced iron pellets (52) from the reactor body (12) .

27. Method according to Claim 26, wherein the lateral openings(30) are modified to each having a chamfer (34) on an inner part of the side wall (14) to increase an opening diameter, wherein preferably the chamfer (34) is only formed in a refractory lining (32) of the side wall (14) .

28. Method according to any of Claims 22-27, wherein the blast furnace reactor comprises tuyeres (28) installed at its side wall ( 14 ) ,wherein at least some of the tuyeres (28) are tightly connected to a reducing gas feed line (54) so that they are configured for injecting hot reducing gas into the reactor body (12) .

29. Method according to any of Claims 22-28, wherein the blast furnace reactor comprises a tapping hole (56) at the bottom of the blast furnace reactor body, wherein the method comprises installing inside the reactor body (12) a central hot direct reduced iron pellet discharge system (58) configured to discharge hot direct reduced iron pellets (52) through the tapping hole (56) .

30. Use of a reactor (10) having a blast furnace reactor body (12) , wherein a gas guiding element (24) is used and inserted into the blast furnace reactor body (12) to use the blast furnace reactor body (12) and the inserted gas guiding element (24) in a gas-based pressurised counter current shaft furnace direct reduction.

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