TW201814054A - Methods and systems for increasing the carbon content of sponge iron in a reduction furnace - Google Patents

Abstract

A method for producing direct reduced iron having increased carbon content, comprising: providing a carbon monoxide-rich gas stream; and delivering the carbon-monoxide-rich gas stream to a direct reduction furnace and exposing partially or completely reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of resulting direct reduced iron. The carbon monoxide-rich gas stream is delivered to one or more of a transition zone and a cooling zone of the direct reduction furnace. Optionally, providing the carbon monoxide-rich gas stream comprises initially providing one of a reformed gas stream from a reformer and a syngas stream from a syngas source. Optionally, the carbon monoxide-rich gas stream is derived, at least in part, from a carbon monoxide recovery unit that forms the carbon monoxide-rich gas stream and an effluent gas stream. Optionally, the method still further includes providing a hydrocarbon-rich gas stream to one or more of a transition zone and a cooling zone of the direct reduction furnace, with and/or separate from the carbon monoxide-rich gas stream.

Description

 Method and system for increasing carbon content of sponge iron in reduction furnace  

U.S. Patent Application Serial No. 14/748,413, the entire disclosure of which is incorporated herein by reference in its entirety the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire content Part of the number continues to apply (CIP), the contents of which are hereby incorporated by reference in its entirety.

The invention generally relates to methods and systems for increasing the carbon content of sponge iron in a direct reduction (DR) furnace.

Also known as sponge iron direct reduced iron (DRI), typically in a moving bed or vertical shaft reactor, in a reactive gas stream containing a reducing agent such as H ₂ and CO, from iron ore The reaction is produced. The following is the equilibrium limit for the overall reaction formula Fe ₂ O ₃ +3H ₂ 2Fe+3H ₂ O (1)

Fe ₂ O ₃ +3CO 2Fe+3CO ₂ (2)

In commercial DR processes, DRI products still contain unreacted iron oxide, which can be as much as 15.0% by weight. Due to the equilibrium nature of the reactions (1) and (2), it will not be economical to achieve complete (i.e., 100.0%) reduction in the reduction reactor. In fact, when the degree of reduction is close to 100.0%, it is necessary to stay in the reduction reactor for an excessively long period of time to remove residual oxygen from the partially reacted materials. Although the reduction reaction rate can be increased and increased to some extent by increasing the temperature, this temperature increase is limited by the fact that the operating temperature must be maintained below the sintering temperature so that the formation inside the reduction reactor does not form a mass. The fact of the cluster. Thus, in the effluent of a conventional commercial reduction reactor, the typical reduction is maintained at a certain percentage in the range of 85.0-95.0%, depending on the quality of the oxide material and the operating conditions of the plant.

In addition to scrap and pig iron, the DRI of such products can also be used as a source of low residual iron primarily through electric arc furnaces (EAF) in steelmaking equipment. The EAF arc melt system by way of the interposed molten material, typically in order to burn the carbon and impurity Fe ₃ C (if any), which will be accompanied by the injection of oxygen. Partial or complete combustion of the carbon and oxygen provides a uniform source of internal energy to the EAF when oxygen is injected into the EAF. Furthermore, the conversion of Fe ₃ C to iron and carbon is an exothermic reaction which can improve the thermal efficiency of the EAF. Therefore, the carbon content of the DRI can be interpreted as a source of energy, and this energy will eventually be used in the EAF when the DRI melts.

Although other carbon sources such as coal or rubber can be added to the electric arc furnace for the same purpose, the yield obtained by the particle blowing action and the impurities in the carbon source is obviously lower than that. Composite carbon in DRI. Therefore, before placing the directly reduced iron into the EAF, it is highly desirable to increase the carbon content of the DRI in the reduction step.

Inside the reduction reactor, carbon can be produced by the overall reaction (ie, physical carbon-C) or added to the DRI (eg, chemical carbon-Fe ₃ C): 3Fe+CO+H ₂ Fe ₃ C+H ₂ O (3)

3Fe+2CO Fe ₃ C+CO ₂ (4)

3Fe+CH ₄ Fe ₃ C+2H ₂ (5)

CO+H ₂ C+H ₂ O (6)

2CO C+CO ₂ (7)

CH ₄ C+2H ₂ (8)

Thus, the DRI product (i.e., the physical and chemical properties), the binding of the two main sources of carbon, a reducing-based gas stream of CO and hydrocarbons (e.g., CH _4). Although the content of CO in the reducing gas stream is usually set by the operating conditions of the reducing gas generating device, the hydrocarbon content is adjusted by the operator to suppress the methanation reaction in the reducing furnace. At the same time, the cooling effects caused by the following factors are considered: - the above-mentioned endothermic reactions (5) and (8), - the endothermic recombination reaction catalyzed by iron in the reduction reactor, - the heat directly removed by the hydrocarbon, Compared to most of the gases in the DR equipment, there is a significantly higher heat capacity, and a limited preheating temperature (less than ~400 ° C) of the hydrocarbon stream.

In other words, from the operational point of view, the amount of CO and CH ₄ that can be increased in the reducing gas stream is also limited.

One of the commercial practice methods for circumventing these constraints is to add a hydrocarbon-rich gas stream to the already reduced material mass. This is usually done by injecting natural gas into the hot reducing material (good catalyst) by leaving the reducing zone in the hot reducing material - at a location commonly referred to as the transition zone. Therefore, the carbon content of the product will increase due to the cleavage reaction in this transition zone.

Due to the endothermic nature of the cleavage reaction, this interaction reduces the temperature of the material and the gas, thereby helping to cool the product DRI. However, for equipment where the DRI must exit the reduction furnace at higher temperatures, this cooling effect is considered a negative side effect and usually needs to be minimized.

In commercial DR processes, hydrocarbon sources are typically used to produce reducing agents by catalytic or non-catalytic recombination processes. For catalytic recombination processes, the oxidant required is typically H ₂ O (ie, water vapor) and CO ₂ . For non-catalytic recombination processes, the oxidant required is typically oxygen (O ₂ ). In the latter case, very rapid partial and complete combustion reactions result in H ₂ O and CO ₂ for further homogenization and/or heterogeneous recombination reactions. All recombination processes convert some of the carbon and hydrogen content of the hydrocarbons to CO and H ₂ , respectively. For example, in the case where CH ₄ is the only source of hydrocarbons, the overall reaction process for controlling homogeneous and heterogeneous recombination processes is: CH ₄ + 2O ₂ CO ₂ +2H ₂ O (9)

CH ₄ +1.5O ₂ CO+2H ₂ O (10)

CH ₄ +O ₂ CO+H ₂ +H ₂ O (11)

CH ₄ +0.5O ₂ CO+2H ₂ (12)

CH ₄ +H ₂ O CO+3H ₂ (13)

CH ₄ +CO ₂ 2CO+2H ₂ (14)

Thus, the gas exiting the recombinant process will be a mixture of ₂ and CO, H of the unreacted hydrocarbons with an oxidant, and it is referred to the Department of gas recombination.

In addition to these main reactions, some of the reactions mentioned above may occur with the thermodynamics of the system. The main ones are: CO+H ₂ C+H ₂ O (6)

2CO C+CO ₂ (7)

CH ₄ C+2H ₂ (8)

The carbon obtained from these side reactions has unfavorable consequences for the recombination catalyst, and it is a common practice to prevent such reactions from occurring by controlling the operating parameters of the recombination unit.

Based on the reactions (1) and (2), the oxidants H ₂ O and CO ₂ present in the reducing gas mixture reduce the efficiency of the reduction reaction. Therefore, the operating parameters of the recombination zone in the apparatus will be adjusted in such a way that the recombination gas has a higher CO/CO ₂ and H ₂ /H ₂ O value, which can be passed by CH ₄ High conversion, and at the same time, the H ₂ O and CO ₂ concentrations of the feed gas entering the recombination unit are maintained to the lowest possible extent. Typically, the CH ₄ system flowing from the recombination unit is maintained at less than ~1.0-2.0%, and the results are similar to CO/CO ₂ and H ₂ /H ₂ O, H ₂ /CH in the reformed gas stream. The ratio of ₄ will be higher. Although according to reactions (4) and (7), the higher CO/CO ₂ ratio in the reformed gas stream favors carbon deposition in the reduction reactor, but according to reactions (5) and (8), A high H ₂ /CH ₄ ratio will reduce the chance of carbon deposition. Therefore, by increasing the ratio of CO/CO ₂ , it is apparent that the carburizing ability in the reformed gas can be improved. This is the main focus of the present invention.

The present invention employs an industrially obtainable technique, that is, a membrane module (organic/inorganic/hydrogen) which recovers most of hydrogen and CO ₂ from the recombination gas stream in the apparatus, excluding (ie, separating) other components. Organometallic). This separation usually results in two different gas streams with different chemical compositions: one rich in CO and the other rich in H ₂ . The H ₂ -enriched gas stream is then blended with different gas streams during the process, including but not limited to, recombined unit feed gas stream, cooling gas stream, reducing gas stream, fuel gas stream and many more. The CO-rich gas stream will flow into the transition zone and/or the cooling zone of the reduction furnace to increase the carbon content of the sponge iron.

The exothermic nature of reactions (4) and (7) will allow more gas to be added to the transition zone to maintain high temperatures. Optionally, a hydrocarbon-rich gas stream is blended with the CO-rich gas stream prior to the final injection port.

In the world, hundreds of membrane modules have been installed in refining equipment and petrochemical equipment by different manufacturers. Hydrogen recovery, CO ₂ separation, or H ₂ /CO ratio adjustment are very effective for the effective operation of these equipments. important. Therefore, the use of such devices in novel ways in DR devices will be almost unimpeded.

The invention is not limited to the use of a film assembly. All other separation/adsorption techniques (such as pressure/vacuum and pressure/temperature change adsorption (PSA/VPSA/TSA) units) that meet process requirements can be used to achieve the present invention based on the guidelines presented in this application. Carburizing task.

In an exemplary embodiment, the present invention provides a method of producing direct reduced iron having a higher carbon content, comprising: providing a reformed gas stream from a reformer; and delivering the reformed gas stream to a carbon monoxide recovery unit, Forming a gas stream rich in carbon monoxide and a gas stream enriched with hydrogen; and delivering the carbon monoxide-rich gas stream to the direct reduction furnace, and partially or completely exposing the reduced iron oxide to enrichment A carbon monoxide gas stream is used to increase the carbon content of the resulting direct reduced iron. The carbon monoxide-rich gas stream is delivered to one of a transition zone and a cooling zone of the direct reduction furnace. Depending on the operating conditions of the reformer, the reformed gas stream produced in the tubular catalytic reformer of the direct reduction apparatus typically contains 50.0-80.0% H ₂ , 20.0-40.0% CO, 1.0-5.0% CO _{2 .} , 0.0-3.0% CH ₄ , and 0.0-5.0% N ₂ , all of which are dry weight. The method further includes cooling the reformed gas stream to a temperature below its saturation in a chiller/condenser, preferably at room temperature, such as 20-50 °C. The method still further includes compressing the reformed gas stream to a pressure of 5.0 to 20.0 bar, preferably 10.0-15.0 bar, in a single or multi-stage compressor disposed prior to flowing into the CO recovery unit. For better efficiency, the carbon monoxide-rich gas stream exiting the CO recovery unit should contain more than 60.0% carbon monoxide, preferably between 70.0 and 90.0%. The method further includes recovering the hydrogen-rich gas stream for use in direct reduction equipment in various potential applications, including, but not limited to, fuel for combustion applications, entry into the recombiner The feed gas and the reducing gas entering the reduction furnace. In the case of using a hydrogen-rich gas stream as a fuel, it can reduce the amount of CO ₂ released into the atmosphere. The method further includes mixing a gas stream enriched in carbon monoxide with a gas stream rich in hydrocarbons, preferably natural gas, to form a final carburizing gas.

The hydrocarbon-rich gas stream should contain more than 80.0% hydrocarbons. Optionally, depending on the chemical composition of the hydrocarbon-rich gas stream, the method includes one or more dehumidifiers and a demister/saturator to reduce the humidity of the hydrocarbon-rich gas stream It is less than 1.0% and is preferably dried. Optionally, depending on the chemical composition of the hydrocarbon-rich gas stream, the process includes a desulfurization step to reduce the sulfur content of the hydrocarbon-rich gas stream to less than 100 ppm, preferably Less than 10ppm. Optionally, depending on the mixing ratio between the hydrocarbon-rich gas stream and the CO-rich gas stream, the system includes a preheater to raise the temperature of the final carburizing gas to no more than The temperature of 400 ° C is preferably at a temperature between 50 ° C and 300 ° C. The method also includes injecting the final carburizing gas onto the agglomerates of material that have been reduced in the reduction reactor.

In another exemplary embodiment, the present invention provides a method for producing direct reduced iron having a higher carbon content, comprising: providing a gas stream rich in carbon monoxide; and the gas rich in carbon monoxide The stream is conveyed to a direct reduction furnace, and the partially or completely reduced iron oxide is exposed to a gas stream rich in carbon monoxide to increase the carbon content of the resulting direct reduced iron. The carbon monoxide-rich gas stream delivered to the direct reduction furnace contains at least 60% CO prior to mixing with any other gas stream. The carbon monoxide-rich gas stream is delivered to one or more of the transition zone and the cooling zone of the direct reduction furnace. Optionally, the step of providing the carbon monoxide-rich gas stream comprises providing a recombiner (such as a catalytic reformer (eg, tubular recombiner), a non-catalytic recombiner (eg, a partial oxidation reaction) at the outset. Recombinant gas stream from a composite recombiner (eg, an autothermal reformer or a two-stage recombiner), and from a source of synthetic gas (eg, gasifier, coke oven gas source, or blast furnace) One of the synthetic gas streams. Optionally, the carbon monoxide-rich gas stream is at least partially derived from a carbon monoxide recovery unit which forms a carbon monoxide-rich gas stream and an exhaust gas stream. The carbon monoxide-rich gas stream exiting the carbon monoxide recovery unit includes at least 60% CO. Optionally, the carbon monoxide recovery unit operates in parallel with a bypass line, the carbon monoxide recovery unit and the bypass line each providing a portion of the carbon monoxide-rich gas stream. Optionally, the method also includes recovering the exhaust gas stream for use in a direct reduction apparatus. Optionally, the method further comprises providing a hydrocarbon-enriched gas stream to a direct reduction furnace having the carbon monoxide-rich gas stream. Optionally, the method further comprises providing a hydrocarbon-rich gas stream to one or more of the transition zone and the cooling zone of the direct reduction furnace.

5‧‧‧ method

7‧‧‧ method

9‧‧‧ method

10‧‧‧Reorganization unit

12‧‧‧Recombinant gas flow

14‧‧‧Heater/Condenser

16‧‧‧Compressor

18‧‧‧Metal components or CO recovery unit

20‧‧‧ Gas stream rich in CO

22‧‧‧Enriched with H ₂ gas flow

24‧‧‧Mixer

26‧‧‧Preheater

28‧‧‧DR furnace (direct reduction furnace)

30‧‧‧Main reduction area

32‧‧‧Transition area

34‧‧‧Cooling area

36‧‧‧ Gas stream rich in hydrocarbons

38‧‧‧Dehumidification unit

40‧‧‧Desulfurization unit

50‧‧‧ Bypass pipeline

The present invention is illustrated and described herein with reference to the various drawings in which like reference numerals are used to appropriately indicate similar method steps/system components, and wherein: Figure 1 illustrates A schematic diagram of a typical embodiment of a method for injecting a carbon monoxide gas stream into a reduction furnace of the present invention to increase the carbon content of the sponge iron; and FIG. 2 is an illustration of adding a sponge iron in the reduction furnace of the present invention A schematic diagram of another exemplary embodiment of a method for carbon content, wherein a hydrocarbon-rich gas stream having adjusted and unadjusted moisture and sulfur content is associated with carbon monoxide rich in FIG. Gas stream blending; and Figure 3 is a schematic view showing another exemplary embodiment of a method of increasing the carbon content of sponge iron in the reduction furnace of the present invention, optionally using a carbon monoxide recovery unit bypass a pipeline, optionally using a recombiner or other source of syngas, and optionally rich in a hydrocarbon gas stream, with adjusted and unadjusted moisture and sulfur contents, and with Figures 1 and 2 rich Blending carbon monoxide gas stream, and / or the transition region is directly supplied to the reduction furnace and / or the cooling zone.

The present invention provides an efficient and cost effective method for increasing the carbon content of DRI in a DR device. It provides a carbon monoxide-rich gas stream with limited impurities that is injected directly into the high heat and partially or completely reduced material mass in the reduction furnace, or first with other gases (eg, rich) The gas stream containing hydrocarbons is blended. The combination with the coking reaction significantly increases the carbon content of the resulting DRI while maintaining the mass at elevated temperatures.

For any type of DR device that uses the reorganization step, the following are its main advantages:

- The design is simple and straightforward in engineering, construction and operation.

- A conventional method of injecting a hydrocarbon-rich gas stream into a reduction furnace by increasing the carbon content of the material by an endothermic hydrocarbon cracking reaction; thus lowering the temperature of the material. However, the present invention enhances the carbon content of iron by an exothermic reaction while maintaining the heat of the reduction zone, resulting in improved equipment productivity. This is a plus for DR equipment that produces heat exhaust DRI.

- This method uses relatively few devices.

- This method can be combined with a cold or hot exhaust DRI device.

- Various components have been commercialized by various suppliers, and their design and operation in other documents have been well documented.

- The capital expenditure and operating costs required for the proposed system are reasonable.

- Integrating the present invention into existing DR devices does not affect the normal operation of such devices.

- This design can be used as an auxiliary plug-in component for existing DR equipment.

- The design is independent of combustion/reaction. Therefore, its operation is quite safe and reliable.

Referring now specifically to Figure 1, in an exemplary embodiment, the method 5 of the present invention includes the use of a cooler/condenser 14 and will be from any design of the recombination unit 10 (such as a catalytic reformer (e.g., tubular) Recombiner), a non-catalytic recombiner (eg, a partial oxidation reactor), or a composite recombiner (eg, an autothermal recombiner or a two-stage recombiner), or capable of producing a relatively high CO/CO ₂ ratio The reformed gas of at least a portion of any other reducing gas generating unit containing CO gas is cooled to near ambient temperature (e.g., 30 ° C). Preferably, the reformed gas stream 12 contains at least 20.0% CO. The cooler/condenser 14 can be operated by direct contact cooling, indirect contact cooling, chilled cooling, and the like. During this cooling step, the reformed gas will lose some of its water content, which in turn will improve the carburizing ability of the reformed gas. The cooled/dried recombination gas is optionally passed through a compressor 16 which can increase its pressure (e.g., increased to 15 bar) because most separation/adsorption methods work best at higher pressures. . During this compression step, the gas will lose even more moisture and further improve the carburizing ability.

The compressed gas, after optionally adjusting the temperature, will flow into the membrane module 18 system for CO recovery. In this step, any other type of CO recovery mechanism, such as PSA/VPSA/TSA, freezing, etc., can also be used. After this step, the CO-enriched gas stream 20, comprising a system with more than 60.0% of CO, and the H ₂ enriched gas stream 22, may correspondingly contain more than 70.0% of H _2.

The CO-enriched gas stream 20 from the CO recovery unit 18 is optionally passed through a preheater 26 and heated to 50-300 °C. The CO-rich gas stream 20 is then introduced into a DR furnace 28 located below the primary reduction zone 30 (e.g., into the transition zone 32 and/or the cooling zone 34), the CO-rich gas stream The 20 series is in contact with partially or fully reduced iron oxide and is based on the known reaction 2CO C+CO ₂ and 3Fe+2CO Fe ₃ C+CO _{2 is} used to deposit carbon. Generally, the partially or completely reduced iron oxide in the transition zone 32 and/or the cooling zone 34 previously contains from 0.0% to 3.0% of bound carbon, and after the addition of the CO-rich gas stream, Contains up to 4.5% bound carbon.

In addition, the gas 22 discharged from the CO recovery unit 18 (rich in H ₂ ) may be used as a fuel, a cooling gas, a syngas, or a process gas in different parts of the DR apparatus, or it may be Export to another device.

Referring to Figure 2, in another exemplary embodiment, the method 7 of the present invention includes the use of a cooler/condenser 14 and will be from any design of the recombination unit 10 (such as a catalytic recombiner (e.g., tubular recombination) a non-catalytic recombiner (eg, a partial oxidation reactor), or a composite recombiner (eg, an autothermal recombiner or a two-stage recombiner), or capable of producing a relatively high CO/CO ₂ ratio The reformed gas of at least a portion of any other reducing gas generating unit containing CO gas is cooled to near ambient temperature (e.g., 30 ° C). Preferably, the reformed gas stream 12 contains at least 20.0% CO. The cooler/condenser 14 can be operated by direct contact cooling, indirect contact cooling, chilled cooling, and the like. During this cooling step, the reformed gas will lose some of its water content, which in turn will improve the carburizing ability of the reformed gas. The cooled/dried recombination gas is optionally passed through a compressor 16 which can increase its pressure (e.g., increased to 15 bar) because most separation/adsorption methods work best at higher pressures. . During this compression step, the gas will lose even more moisture and further improve the carburizing ability.

The compressed gas, after optionally adjusting the temperature, will flow into the membrane module 18 system for CO recovery. In this step, any other type of CO recovery mechanism, such as PSA/VPSA/TSA, freezing, etc., can also be used. After this step, the CO-enriched gas stream 20, comprising a system with more than 60.0% of CO, and the H ₂ enriched gas stream 22, may correspondingly contain more than 70.0% of H _2.

The gas 22 from the CO recovery unit 18 (rich in H ₂ ) can be used as a fuel, cooling gas, syngas, or process gas in different parts of the DR plant, or it can be exported to Inside another device.

In addition, a hydrocarbon-rich gas stream 36 (e.g., natural gas) is mixed with CO in the mixer 24 prior to being introduced into the DR furnace 28 with the CO-rich gas stream 20. Gas stream 20 is blended. Optionally, if the hydrocarbon-rich gas stream is wet, one or more dehumidifying units 38 may be used to dry the gas to inhibit the decarburization reaction. Optionally, if the hydrocarbon-rich gas stream carries a significant amount of sulfur compound, a desulfurization unit 40 can be used, and before it flows into the reduction furnace, the total sulfur content is controlled to Below 100 ppm, preferably below 10 ppm. In this case, the preheater 26 can be used to enrich the hydrocarbon-rich gas stream 36 prior to mixing with the CO-rich gas stream 20 in the mixer 24. The hydrocarbon gas stream 36 is preheated at different temperatures (e.g., about 350-400 ° C), thereby allowing it to be preheated after about 50-300 ° C of the mixer 24 Minimize the formation of soot. Thus, in all embodiments, the preheater 26 can alternatively be placed before or after the mixer 24.

Thus, the present invention utilizes the industry's existing technology, that is, a thin film module unit (organic/organic/organic metal) which recovers from the recombination gas stream in a device by excluding (ie, separating) other components. Partially hydrogen and or CO ₂ . This separation effect usually two different kinds having different chemical compositions of the gas streams: one kind rich in CO and the other is rich in H _2. The H ₂ -rich gas stream is then blended with the different gas streams in the process, including, but not limited to, a feed gas stream fed to the reformer unit, the cooling gas stream, the reduction A gas stream, a fuel gas stream, and the like. The CO-rich gas stream flows into the transition zone and/or the cooling zone of the reduction furnace to increase the carbon content of the sponge iron. The exothermic properties of the above reactions (4) and (7) allow it to add more gas to the transition zone to maintain high temperatures. Optionally, the hydrocarbon-rich gas stream is blended with the CO-rich gas stream prior to the final injection port.

In the world, hundreds of membrane modules have been installed in refining equipment and petrochemical equipment by different manufacturers. Hydrogen recovery, CO ₂ separation, or H ₂ /CO ratio adjustment are very effective for the effective operation of these equipments. important. Therefore, the use of such devices in a novel manner in DR devices will be almost unimpeded.

The invention is not limited to the use of a film assembly. All other separation/adsorption techniques (such as pressure/vacuum and pressure/temperature change adsorption (PSA/VPSA/TSA) units) that meet process requirements can be used to achieve the present invention based on the guidelines presented in this application. Carburizing task.

Figure 3 provides a further improvement of the method 9 of the present invention. Optionally, the CO recovery unit 18 can be bypassed partially or completely by the bypass line 50. Bypass 30-60% is the most likely scenario. However, depending on the chemical composition of the reformed gas or syngas, it may also be a lower or higher percentage from any of 0-100%. If a 100% bypass is employed, the compressor 16 can operate at approximately 2-7 bar instead of 10-15 bar. However, if a 100% bypass is employed, along the bypass line 50, a drying unit (not shown) may be included. Optionally, the reformer 10 and the reformed gas 12 (and associated components) may be replaced with a gas from a coal gasifier or the like. It should be noted that the recombiner 10 can be a catalytic recombiner (eg, a tubular recombiner), a non-catalytic recombiner (eg, a partial oxidation reactor), or a composite recombiner (eg, an autothermal recombiner) Or a two-stage reorganizer). The coal gasifier can be replaced with another type of gasifier, coke oven gas source, outlet gas source, blast furnace, or the like - collectively referred to herein as a source of synthesis gas. The two-stage CO recovery unit 18 or the like is preferably used to achieve 35-70% of the CO-rich gas stream, which is delivered to the DR furnace 28, depending on the chemical composition of the syngas. Area 32. Optionally, the hydrocarbon-rich gas stream 36 is conditioned with or without the dehumidifier 38, and the sulfur content is adjusted by the desulfurizer 40, and the preheater 26 is used. Under preheating, it is blended with the carbon monoxide-rich gas stream 20 and/or is delivered directly to the transition zone 32 and/or cooling zone 34 of the DR furnace 28. In particular, all of the transition zone/cooling injection can be provided through openings in the transition zone 32 and/or cooling zone 34 of the DR furnace 28. The key aspect is the partially or completely reduced iron oxide, which is exposed to a CO-enriched gas stream 20 and, optionally, a hydrocarbon-rich gas stream 36.

Although the present invention is described herein with reference to the preferred embodiments and specific examples thereof, other embodiments and examples may perform similar functions and/or obtain similar results. obviously. All such equivalents and examples are intended to be within the spirit and scope of the invention and are intended to be

Claims (20)

 A method of producing direct reduced iron having an increased carbon content, comprising: providing a gas stream rich in carbon monoxide; and delivering the carbon monoxide-rich gas stream to a direct reduction furnace and partially or completely reducing it The iron oxide is exposed to the carbon monoxide-rich gas stream to increase the carbon content of the resulting direct reduced iron.    The method of claim 1, further comprising providing a hydrocarbon-rich gas stream to the direct reduction furnace having the carbon monoxide-rich gas stream.    The method of claim 1, further comprising providing a hydrocarbon-rich gas stream to one or more of a transition zone and a cooling zone of the direct reduction furnace.    The method of claim 1, wherein the carbon monoxide-rich gas stream comprises at least 60% CO prior to mixing with any other gas stream.    The method of claim 1, wherein the carbon monoxide-rich gas stream is delivered to one or more of a transition zone and a cooling zone of the direct reduction furnace.    The method of claim 1, wherein the step of providing the carbon monoxide-rich gas stream comprises providing a recombination gas stream from a recombiner at the beginning, and one of the synthesis gas streams from a synthesis gas source. By.    The method of claim 1, wherein the carbon monoxide-rich gas stream is at least partially derived from a carbon monoxide recovery unit that forms the carbon monoxide-rich gas stream and an exhaust gas stream.    The method of claim 7, wherein the carbon monoxide-rich gas stream exiting the carbon monoxide recovery unit comprises at least 60% CO.    The method of claim 7, further comprising recovering the offgas gas stream for use in a direct reduction apparatus.    The method of claim 7, wherein the carbon monoxide recovery unit is operated in parallel with a bypass line, the carbon monoxide recovery unit and the bypass line each providing a portion of the carbon monoxide-rich gas stream.    A system for producing direct reduced iron having an increased carbon content, comprising: a member for providing a gas stream rich in carbon monoxide; and a means for delivering the carbon monoxide-rich gas stream to a Directly reducing the components of the furnace and exposing the partially or fully reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of the resulting direct reduced iron.    The system of claim 11 further comprising a source of hydrocarbons for providing a hydrocarbon-rich gas stream to the direct reduction furnace having the carbon monoxide-rich gas stream.    The system of claim 11 further comprising a source of hydrocarbons for providing a hydrocarbon-rich gas stream to one or more of the transition zone and the cooling zone of the direct reduction furnace.    The system of claim 11, wherein the carbon monoxide-rich gas stream comprises at least 60% CO prior to mixing with any other gas stream.    The system of claim 11, wherein the carbon monoxide-rich gas stream is delivered to one or more of a transition zone and a cooling zone of the direct reduction furnace.    The system of claim 11, wherein the means for providing the carbon monoxide-rich gas stream comprises a recombiner for providing a recombination gas stream, and a synthesis gas source for providing a synthesis gas stream .    The system of claim 11, wherein the means for providing the carbon monoxide-rich gas stream comprises at least a portion comprising a carbon monoxide recovery unit that forms the carbon monoxide-rich gas stream and an exhaust gas stream.    The system of claim 17, wherein the carbon monoxide-rich gas stream exiting the carbon monoxide recovery unit comprises at least 60% CO.    The system of claim 17 further comprising a means for recovering the exhaust gas stream for use in a direct reduction device.    The system of claim 17, wherein the carbon monoxide recovery unit is operated in parallel with a bypass line, the carbon monoxide recovery unit and the bypass line each providing a portion of the carbon monoxide-rich gas stream.