WO2005119380A2

WO2005119380A2 - Computer implemented control process for the production of molten pig iron

Info

Publication number: WO2005119380A2
Application number: PCT/IB2005/051759
Authority: WO
Inventors: Antonello Di Donato; Eros Faraci; Paolo Granati
Original assignee: Centro Sviluppo Materiali S.P.A.
Priority date: 2004-05-31
Filing date: 2005-05-30
Publication date: 2005-12-15
Also published as: ITRM20040267A1; WO2005119380A3

Abstract

A computer implemented control process for the production of molten pig iron using computerized means for controlling and varying the flow rate of fuel supply, and/or the flow rate of oxygen injection into a reactor, wherein a reduction reaction of iron ores takes place, in order to vary the value of the oxidation degree (GO) of the resulting gas, equal to the ratio (%H2O + %CO2) / (%H2O + %CO2 + %CO + %H2), and the value of the temperature of the resulting gas in the reactor. Therefore, the control logic of the process allows to control the operating parameters of the process for the production of molten pig iron, allowing the cutting down on fuel consumptions and a good thermal efficiency of the transformation.

Description

COMPUTER IMPLEMENTED CONTROL PROCESS FOR THE PRODUCTION OF MOLTEN PIG IRON DESCRIPTION Field of the invention The present invention relates to a computer implemented control process for the production of molten pig iron and, more specifically, it refers to the control logics of the process. State of the Art The state of the art is already aware of computer implemented processes for controlling metal transformation processes. In particular, U.S. Pat. 4,512,802 discloses a computer implemented process for optimizing the decarburization of a determined mass of molten metal by controlling various operating parameters. Moreover, several processes and technologies for the production of molten pig iron are known. Among them, the CleanSMelt technology, to which U.S. Pat. 6,352,574 and 6,146,440 relate, provides the production of molten pig iron starting from coal and iron ore, hereinafter also referred to as "raw materials", made to react in a liquid slag environment. The reaction products are molten pig iron and reduction carbon monoxide CO. CleanSMelt technology provides that the process be conducted in a reaction chamber or reactor where two process stages take place in two separated zones, hereinafter referred to as "the dresser" and "the converter" for the top zone and the bottom zone, respectively.

The process stage taking place in the dresser provides that the iron ore, introduced by means of a plurality of nozzles and transported by a stream of oxygen or of a mixture of oxygen and air, comes in contact with a hot and reducing gas, generated in the bottom zone of the reactor, i.e. in the converter; under such conditions, a combustion of the gas coming from the converter causes a pre-heating and pre- reduction of the iron ore. The pre-heated and pre-reduced iron ore is fed into the converter. The process stage taking place in the converter provides the final reduction of the pre-reduced iron ore and the generation of molten pig iron. A fuel, e.g. fine coal, and a supporter of combustion, e.g. oxygen, together with fluxes, a carrier gas and a stirring gas are introduced into the converter, where the hot and reducing gas which enters the dresser is produced together with pig iron. The dresser is connected to a discharge conduit for discharge of process gas.

The energy required by the chemical reactions and physical transformations taking place in the converter is mainly provided by the post-combustion of reducing gas with oxygen. The oxygen injected into the converter will hereinafter also be referred to as "primary" or "secondary" according to whether it is injected to a lower or higher level of the converter, while the oxygen injected in the dresser can also be referred to as "tertiary". Such a reducing gas is generated from coal gasification, when coal interacts both with primary oxygen injected together with said coal, and with oxygen bound to the pre-reduced iron ore. Coal and primary oxygen injection takes place into a molten slag bath, which is fed by mineral gangue, ashes from coal and fluxes and which floats onto the molten pig iron bath that is being formed. In the converter, iron oxides are reduced into metallic iron when they react with the coal scattered in said slag and with carbon monoxide that generates from coal gasification with primary oxygen: at the same time, iron is carburized resulting in molten pig iron. To support these transformations, it is used the chemical and thermal energy provided by oxygen injected in the slag and by coal introduced by injection, in the form of fine coal, or added partly as fine coal and possibly partly in the form of sized coal introduced by gravity.

The reactor suitable to carry out the described process for the direct production of pig iron starting from iron ore and pit coal comprises a reaction chamber or reactor having:

- a first top zone of a substantially symmetrical cylindrical shape; - a system for supplying iron ore, oxygen or a mixture of oxygen and air to said top zone;

- a discharge conduit connected with the top zone;

- a second zone arranged beneath the first zone, of a substantially symmetrical cylindrical shape, and communicating with the first zone through a connector, possibly shaped as a truncated cone;

- first means for supplying oxygen to the bottom zone;

- second means for supplying oxygen, fine coal, fine fluxes and a carrier gas to the bottom zone;

- means for supplying stirring gas to the bottom zone. However, the coal used for the transformation is in excess with respect to the stoichiometric one required for iron oxide reduction, and it is partially gasified by primary gaseous oxygen expressly injected together with the coal. Thus, gasification CO that adds to the reduction CO is generated. Since in the operations coal is used that, beside carbon, contains variable quantities of hydrogen, coal gasification entails the formation of a gaseous mixture in which, beside CO, H₂ and small quantities of CO₂ and H₂O are present. The chemical process of transformation of the raw materials taking place in the reactor, i.e. the reaction between slag-dissolved iron oxide and coal scattered in the liquid slag with production of molten pig iron and carbon monoxide CO, is overall endothermic. Hence, energy has to be provided to the reaction system in order to support the transformation itself. In the CleanSMelt process the energy is provided in the form of heat developed by the combustion, with secondary gaseous oxygen, of the stream comprising reduction CO, gasification CO and H₂.

The combustion can be conducted so as to obtain different oxidation degrees, GOs, of the resulting gas, corresponding to different developments of heat quantities. The oxidation degree GO of the resulting gas is defined by the following expression:

GO = (%H₂O + %C0₂) / (%H₂O + %CO₂ + %CO + %H₂).

To obtain a predetermined quantity of heat, a certain mass of combustible gas can be burned, reaching the appropriate GO value.

However, thus coal consumptions for producing pig iron are high, and the transfer efficiency of heat, generated in the combustion, to the environment where the reduction reactions take place can be not very high. Such efficiency of heat transfer is quantified by the parameter Heat Transfer Efficiency, HTE, defined as:

HTE = [ 1 - (H(Tg) - H(Tb))/ DHpc ] where: - H(Tg) is the gas enthalpy after post-combustion, as calculated at the temperature of gas;

- H(Tb) is the gas enthalpy after post-combustion, as calculated at the bath temperature;

- DHpc is the variation in the enthalpy of the post-combustion reaction calculated at the bath temperature, decreased by the heat losses to the outside.

An alternative foresees burning a smaller mass of combustible gas at a higher GO value. This way of acting entails a cutting down on coal consumption; on the other hand, it is crucial that the gas produced by the combustion be not oxidized to a point, or produced under oxidizing conditions, such as not to allow the existence of the reducing conditions for the reduction of iron oxides.

In short, for a cutting down on coal consumptions it is crucial that: the combustible gas be oxidized at maximum GO value, and, for the practical aspects of the process, it is crucial that: the oxidized gas does not interact with the reducing environment in which the reduction reactions of iron oxides are carried out, and the heat generated in the combustion is transferred to the reducing environment to support the endothermic reduction reactions. The three requisites outlined above are tentatively met by a control logic of the process.

The present invention aims at safeguarding the control logics of the process according to the control criteria described herein, after which besides with carbon may be adopted also with another solid, liquid or gaseous fuel.

According to preferred embodiments, the present invention applies in case of use of coal, hydrocarbons, in particular methane, hydrogen, possibly in a mixture with carbon monoxide, and combinations thereof.

Process modeling on the basis of the experimentation carried out indicates that energy consumptions, assessed with reference to coal, are not significantly modified when changing the typology of fuel used, be it a liquid or gaseous hydrocarbon or a mixture of CO and H₂ (synthesis gas).

The versatility of application of the computer implemented process according to the present invention is irrespective of the combustion mechanism. E.g., this computer implemented process can also apply to methane, regardless of the fact that the combustion of this saturated hydrocarbon exhibits characteristics differing from those of coal.

In fact, methane combustion occurs in two stages:

1. Endothermic cracking of the methane with cooling of the combustion zones CH₂ -> C + 2H₂ (1 )

2. Releasing heat by effect of the esothermic combustion reactions 2H₂ + O₂ -> 2H₂O (2) C+ ¹/₂ O₂ -> CO₂ (3) CO + ¹/₂ O₂ -> CO₂ (4) Moreover, hydrogen oxidation is not effected in the two stages of combustion (3) and post-combustion (4), as is the case for coal, but in a single stage (1 ).

Summary of the invention A primary object of the present invention is to carry out a computer implemented process allowing to control the main operating parameters of the transformation process of raw materials for the production of molten pig iron, attaining high values of the degree of oxidation GO of the combustible gas, and values near to the upper limit of the 100% of the parameter HTE of efficiency of thermal transfer of heat, generated by the combustion, to the environment where the reduction reactions of iron oxides take place. The adjustment of the HTE parameter is carried out by a controlling of the temperature, Tgas, of the resulting gas present in the process reactor. Hence, the present invention aims at solving the above-discussed problems by carrying out, as per claim 1 , a computer implemented control process for the production of molten pig iron, wherein it is provided computerized means apt to control a variation in the supply flow rate of fuel, and/or in oxygen injection into a reactor suitable for the carrying out of a reduction reaction of iron ore in order to vary the value of the oxidation degree GO of the resulting gas, defined by the following expression GO = (%H₂O + %CO₂) / (%H₂O + %CO₂ + %CO + %H₂), and of the temperature, Tgas, of the resulting gas in the reactor, the process comprising the following stages: a) detecting, at predetermined times, the actual situation of at least the oxidation ■ degree (GO) of the resulting gas and comparing it to a target value (GOfin) to be reached, b) varying the injection flow rate of primary oxygen (0x1 ) and/or of secondary oxygen (Ox2) in case the oxidation degree (GO) differs from the target value (GOfin), c) detecting the situation of the oxidation degree (GO) of the resulting gas with regard to a target value (GOfin) to be reached, d) carrying out stage a) when the value of the oxidation degree (GO) of the resulting gas has reached the target value (GOfin), e) controlling the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (0x2) with regard to a maximum value allowed, when the value of the oxidation degree (GO) of the resulting gas has not reached the target value (GOfin), f) executing stage b) when the injection flow rate of the primary oxygen (Ox1) and/or of the secondary oxygen (0x2) is lower than the maximum value allowed, g) varying the supply flow rate of fuel, when the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (0x2) is higher than the maximum value allowed, h) carrying out stage a). The proposed solution allows, through process control logics, a lesser consumption of fuel and a higher efficiency of molten pig iron production. The control procedures were developed to reach and keep to desired values the thermal state of the system, contained in the process reactor and consisting of metal, slag, gas and refractory, by varying the heat quantity generated in the reactor The heat quantity is varied by acting on the supply flow rate, e.g. of coal, and/or the flow rate of oxygen in the reactor in which the reduction reactions of the iron oxides take place, so as to vary the oxidation degree, GO, of the resulting gas and the temperature, Tgas, of the resulting gas in said reactor.

Accordingly, the injection flow rate of iron ores and therefore the plant productivity may be varied, since, by acting on the GO and HTE values, the reduction reactions of iron oxides can be supported and the thermal state of the system can be stabilized.

The acceptable indicative values of the typical parameters in the operating conditions of the transformation process are reported in the following table.

Next table summarizes instead the most important qualitative relationships between operating parameters and operating variables.

The dependent claims describe some other preferred variants of the invention.

Brief description of the Figures

Additional features and advantages of the invention will be made further apparent in the light of the detailed description of preferred, yet non-exclusive, embodiments of a computer implemented control process for the production of molten pig iron illustrated, by way of a non-limiting example, with the aid of the annexed figures, wherein:

Fig. 1 shows a reactor in which the stages of the process of the invention can take place;

Fig. 2 shows a flow chart of the process of the invention comprising the operations to be carried out to increase the GO by a first adjusting mode;

Fig. 3 shows a flow chart of the process of the invention comprising the operations to be carried out to reduce the GO by a first adjusting mode; Fig. 4 shows a flow chart of the process of the invention comprising the operations to be carried out to increase the GO by a second adjusting mode;

Fig. 5 shows a flow chart of the process of the invention comprising the operations to be carried out to reduce the GO by a second adjusting mode;

Fig. 6 shows a flow chart of the process of the invention comprising the operations to be carried out to reduce the temperature of the gas in the reactor;

Fig. 7 shows a flow chart of the process of the invention comprising the operations to be carried out to increase the temperature of the gas in the reactor;

Fig. 8 shows the variation of some process variables as a function of time in a first example of adjustment of the oxidation degree; Fig. 9 shows the variation of some process variables as a function of time in a second example of adjustment of the oxidation degree;

Fig. 10 shows the variation of the temperature of the gas in the reactor as a function of time adjusting the oxidation degree.

Detailed description of preferred embodiments of the invention In Fig. 1 it is shown a reactor in which the stages of the process of the invention can take place. Such a reactor comprises:

- a first chamber or dresser 1 , of a substantially cylindrical shape;

- means 5 for supplying iron ore to the dresser 1 ;

- first means 6 for supplying oxygen to the dresser 1 ; - a second chamber or converter 2, arranged beneath the dresser 1 , substantially of cylindrical symmetrical shape and communicating with the dresser 1 through a connector 3, optionally shaped as a truncated cone; - a discharge conduit 4 for process gases, connected to the top portion of the dresser 1 ;

- second means 7, e.g. lances or tuyeres, for supplying oxygen to the converter 2;

- means 8, e.g., lances or tuyeres, for supplying oxygen, fine coal, fine fluxes to the converter 2;

- means 9 for outletting the molten pig iron;

- a system for supplying stirring gas, advantageously inert gas or hydrocarbons, to the bottom zone, not shown in figure.

In a first variant, the process for the production of molten pig iron comprises the following two stages:

- a first stage, taking place in the dresser 1 , provides that the iron ore, introduced through the supplying means 5 and carried in a stream of oxygen or of an oxygen/air mixture, comes into contact with hot and reducing gas, generated in the bottom zone of the reactor, i.e. in the converter 2; under these conditions, the combustion of the gas coming from the converter 2 causes the pre-heating and the pre-reduction of the iron ore. The pre-reduced and pre-heated iron ore is fed into the converter 2.

- a second stage, taking place in the converter 2, provides the final reduction of the pre-reduced matter and the formation of molten pig iron. In the converter 2 there are introduced the fuel and a supporter of combustion, like oxygen, beside fluxes, a carrier gas and a stirring gas, e.g. an inert gas; together with the pig iron, the hot reducing gas entering the dresser 1 is produced.

In a second variant, the process for the production of molten pig iron comprises the following two stages: - in the dresser 1 , the iron ore, introduced through the supplying means 5 and carried under a stream of oxygen or oxygen/air mixture, comes into contact with hot and reducing gas, generated in the bottom zone of the reactor, i.e. in the converter 2; under these conditions, the combustion of the gas coming from the converter 2 causes the pre-heating and the pre-reduction of the iron ore; the pre-reduced and pre-heated iron ore is fed into the converter 2;

- in the converter 2, there are optionally introduced a fraction of iron ore, a fuel, like, e.g., fine coal, and a supporter of combustion, e.g. oxygen, besides fluxes, a carrier gas and a stirring gas, e.g., hydrocarbons; in such an environment, there occurs a final reduction of the iron oxides, either incoming as pre-reduced matter from the dresser 1 or introduced directly into the converter 2 with formation of molten pig iron, and together with the molten pig iron the hot and reducing gas that enters into the dresser 1 is produced. The introduction of the iron ore directly into the converter 2, at the level of the liquid slag, occurs through the supplying means 7, 8.

With reference to Figs. 2 to 7, there are described examples of flow charts of the computer implemented process, subject of the invention, for the adjustment of operating parameters like the oxidation degree GO and the temperature, Tgas, of the gas in the reactor where the process for the production of molten pig iron takes place.

In order to adjust the operating parameters, known plant management and control means is required. Such a computerized means, through the acquiring of transformation process data by suitable transmitting means, optimally manage the various stages of the transformation process.

GO value controlling can be effected, according to the computer implemented process of the invention, e.g. with three modes: coarse, fine, and mixed. Figs. 2 and 3 show the stages of the computer implemented process to be carried out in order to increase or reduce the oxidation degree GO according to the coarse mode. Once detected, in a stage a), the actual GO situation with regard to a target or final GO value, GOfin, to be reached, GO adjusting occurs at a stage b) by varying the flow rate of primary oxygen 0x1 keeping constant the ratio [0x2/(0x1 +Ox2)]=K2. After a second GO detecting at stage c), if the target value GOfin has been reached stage a) is carried out again, otherwise a stage e) is carried out with a controlling of the injection flow rate of the primary oxygen 0x1 and/or of the secondary oxygen 0x2 with regard to a maximum value allowed. Outside of the acceptability range of the flow rate of 0x1 or 0x2, GO adjusting is carried out in a stage g) intervening directly on the flow rate of fuel, e.g. coal dust, QPCI; otherwise, the flow rate of 0x1 and 0x2 is varied again (stage b). Upon reaching the target value GOfin, stage a) is carried out at predetermined times. Figs. 4 and 5 show the stages of the computer implemented process to be carried out in order to increase or reduce the oxidation degree GO according to the fine mode. Upon detecting, in stage a), the actual GO situation with regard to a target GO value, GOfin, to be reached, it is assessed whether the flow rate of 0x2 be lower than a maximum value allowed (stage e). In such a case, GO adjusting takes place by varying the flow rate of secondary oxygen 0x2 keeping constant the sum [0x1 +0x2]=K1 (stage b); otherwise, it is varied the ratio of the total oxygen flow rate to the coal dust flow rate, i.e., [0x1 +0x2]/QPCI (stage g). Then, a second GO detecting is carried out (stage c) and if the target value GOfin has been reached stage a) is carried out, otherwise again a controlling of the injection flow rate of the secondary oxygen 0x2 with regard to a maximum value allowed (stage e) is carried out and then the above-described stages b) or g) are carried out. Upon reaching the target value GOfin, stage a) is carried out at predetermined times. The mixed GO adjusting mode is attained by combining the two preceding modes. This adjusting mode is useful above all when wishing to explore new process conditions.

Figs. 6 and 7 show instead the flow charts of the control logics of the temperature, Tgas, of the gas in the reactor.

The temperature Tgas of the gas in the reactor should be kept within the following acceptability range: 1550°C<T<1700°C. In the first stage a) of said charts it is provided, together with the detecting of the actual situation of the oxidation degree GO of the resulting gas with regard to a target value GOfin to be reached, a checking of the temperature Tgas of the resulting gas with regard to a target or final temperature, Tgasfin, to be reached in the reactor. In Fig. 6 it can be noted how, when the temperature Tgas of the resulting gas is higher than the target temperature Tgasfin and the oxidation degree

GO is lower than or equal to the target value GOfin, in order to reduce the temperature Tgas of the gas in the reactor it is possible, in a stage a1 ), to reduce the heat generated in the reactor itself or to increase the flow rate of a stirring gas. When, instead, the oxidation degree GO is higher than the target value GOfin and the temperature Tgas of the resulting gas is higher than the target temperature Tgasfin, the temperature Tgas can be reduced by reducing the GO through the coarse or fine adjusting modes described in the foregoing, and then carrying out stages b) and subsequent ones in the respective modes. Likewise, in Fig. 7 when the temperature Tgas of the resulting gas is lower than the target temperature Tgasfin and the oxidation degree GO is higher than the target value GOfin, the temperature Tgas can be increased by increasing, in a stage a2), the heat generated in the reactor or by decreasing the flow rate of a stirring gas. When, instead, the oxidation degree GO is lower than or equal to the target value GOfin and the temperature Tgas of the resulting gas is lower than the target temperature Tgasfin, the temperature Tgas can be increased by increasing the GO through the coarse or fine adjusting modes described in the foregoing, carrying out stages b) and subsequent ones in the respective modes.

In both the cases of Figs. 6 and 7, after these stages for adjusting the gas temperature Tgas in the reactor, a checking of the Tgas with regard to the target temperature Tgasfin is carried out. When the target temperature Tgasfin has been reached stage a) is carried out, otherwise the same stages previously carried out, a1 ) or a2) or b) and subsequent ones, are repeated in the respective modes. Therefore, by these computer-implemented processes, it is possible to control the operating parameters of the process for the production of molten pig iron allowing the cutting down on fuel consumptions and a good thermal efficiency of the transformation.

In order to better understand aims, features, advantages and operation modes of the present invention, there are reported two examples with the results of the chemical transformation adjusted by the computer implemented process of the present invention.

Example 1

The following tables show the materials introduced and those leaving the reactor, and their flow rates per ton of pig iron following a transformation process in which iron ore is introduced into the dresser 1. Materials introduced into the dresser 1 and into the converter 2:

Inert gas, introduced into the bottom zone of the converter 2, is used as stirring gas. Materials leaving the dresser 1 and the converter 2:

The values related to the operating parameters of this example are reported in the Table below. Operating conditions of the process:

In Figs. 8, 9 and 10 there are shown examples of plots of the main process variables in different cases.

In Fig. 8, in the case of an example of GO (oxidation degree) adjusting according to the fine mode, the variation with time of the flow rates of primary oxygen 0x1 and of secondary oxygen 0x2 and the entailed variation of the GO value are reported. The following table shows the values of said process variables at three different times.

In Fig. 9, in the case of an example of GO adjusting according to the mixed mode, the variation with time of the flow rate of primary oxygen 0x1 and the entailed pattern of the GO value are reported. The following table shows the values of said process variables at three different times.

In Fig.10 it is shown the variation with time of the gas temperature, Tgas, in the reactor, intervening on the GO value, whose plot is also shown therein. The following table shows the values of said process variables at three different times.

Example 2

The following tables show instead the materials introduced and those leaving the reactor, and their flow rates per ton of pig iron following a transformation process in which iron ore is introduced into the converter 2. Materials introduced into the dresser 1 and into the converter 2:

As stirring gas, gaseous hydrocarbons introduced into the bottom zone of the converter 2 are used, which can also be useful to the carburization of the metal bath.

Materials leaving the dresser 1 and the converter 2:

In the table below the values related to the operating parameters of this example are reported.

Operating conditions of the process:

The hereto-described specific embodiments of the invention do not limit the content of this application, encompassing all variants thereof defined by the claims. Example 3

The following tables show the materials introduced and those leaving the reactor and their flow rates per ton of pig iron following a transformation process in which iron ore is introduced into the dresser 1. Methane is used as fuel. Materials introduced into the dresser 1 and into the converter 2

Methane, introduced into the bottom zone of the converter 2, is used as stirring gas.

Materials leaving the dresser 1 and the converter 2:

Operating conditions of the process:

Example 4

Materials introduced into the dresser 1 and into the converter 2. Fuel used: methane and coal.

Methane, introduced into the bottom zone of the converter 2, is used as stirring gas. Materials leaving the dresser 1 and the converter 2:

In the table below, the values related to the operating parameters of this example are reported.

Operating conditions of the process:

Claims

CLAIMS 1. A computer implemented control process for the production of molten pig iron, wherein it is provided computerized means apt to control a variation in the supply flow rate of solid, liquid or gaseous fuel, and/or in oxygen injection into a reactor suitable for the carrying out of a reduction reaction of iron ore in order to vary the value of the oxidation degree (GO) of the resulting gas, defined by the following expression GO = (%H₂0 + %C0₂) / (%H₂0 + %C0₂ + %CO + %H₂), and of the temperature of the resulting gas (Tgas) in the reactor , the process comprising the following stages: a) detecting, at predetermined times, the actual situation of at least the oxidation degree (GO) of the resulting gas and comparing it to a target value (GOfin) to be reached, b) varying the injection flow rate of primary oxygen (0x1) and/or of secondary oxygen (0x2) in case the oxidation degree (GO) differs from the target value

(GOfin), c) detecting the situation of the oxidation degree (GO) of the resulting gas with regard to a target value (GOfin) to be reached, d) carrying out stage a) when the value of the oxidation degree (GO) of the resulting gas has reached the target value (GOfin), e) controlling the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (0x2) with regard to a maximum value allowed, when the value of the oxidation degree (GO) of the resulting gas has not reached the target value (GOfin), f) executing stage b) when the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (0x2) is lower than the maximum value allowed, g) varying the supply flow rate of fuel, when the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (0x2) is higher than the maximum value allowed, h) carrying out stage a).

2. The computer implemented process according to claim 1 , wherein the fuel is selected from the group consisting of coal, hydrocarbons, in particular methane, hydrogen, optionally in a mixture with carbon monoxide, and combinations thereof.

3. The computer implemented process according to claim 1 or 2, wherein at stage b) the varying of the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (Ox2) is carried out by keeping constant the sum of the flow rates of the primary oxygen (0x1 ) and of the secondary oxygen (0x2).

4. The process according to claim 1 or 2, wherein at stage b) the varying of the injection flow rate of the primary oxygen (0x1 ) and/or of the secondary oxygen (0x2) is carried out by keeping constant the ratio between the flow rate of the secondary oxygen (0x2) and the sum of the flow rates of the primary oxygen (Ox1 ) and of the secondary oxygen (0x2).

5. The computer implemented process according to claim 1 or 2, wherein prior to stage g) the supply flow rate of the fuel is kept constant.

6. The computer implemented process according to one of the preceding claims, wherein at stage a) it is provided a checking of the temperature (Tgas) of the resulting gas with regard to a target temperature (Tgasfin) in the reactor.

7. The computer implemented process according to claim 6, wherein after stage a) it is provided a stage a1) reducing the heat generated in the reactor or increasing the flow rate of a stirring gas when the temperature (Tgas) of the resulting gas is higher than the target temperature (Tgasfin) and the oxidation degree (GO) is lower than or equal to the target value (GOfin).

8. The computer implemented process according to claim 7, wherein stages b) and subsequent ones are carried out when the oxidation degree (GO) is higher than the target value (GOfin).

9. The computer implemented process according to claim 6, wherein after stage a) it is provided stage a2) increasing the heat generated in the reactor or decreasing the flow rate of a stirring gas when the temperature (Tgas) of the resulting gas is lower than the target temperature (Tgasfin) and the oxidation degree (GO) is higher than the target value (GOfin).

10. The computer implemented process according to claim 9, wherein stages b) and subsequent ones are carried out when the oxidation degree (GO) is lower than the target value (GOfin).

11. The computer implemented process according to claims 7 or 9, wherein a checking of the temperature (Tgas) of the resulting gas in the reactor with regard to the target temperature (Tgasfin) is carried out, and stage a) is carried out when the target temperature (Tgasfin) has been reached, otherwise stage a1 ) or stage a2), respectively, are carried out.

12. The computer implemented process according to any one of the preceding claims, wherein iron ores are introduced in the top zone of the reactor.

13. The computer implemented process according to any one of the claims 1 to 11 , wherein iron ores are introduced in the bottom zone of the reactor.

14. The computer implemented process according to any one of the preceding claims, wherein it is introduced in the bottom zone of the reactor, as stirring gas, inert gas and/or hydrocarbons.

15. A computer program comprising program code means apt to carry out all the stages of claims 1 to 11 when loaded into a computer.

16. A computer program according to claim 15, stored on a computer-accessible storage medium.