A direct reduction plant for a direct reduction of iron oxides provided with a gas circulation circuit comprising: - a reactor (1) having a reduction area (2) adapted to be charged with said iron oxides; - an external source (20) of make-up gas; - a recovery and treatment line (10), arranged downstream of the reactor (1), to recover and treat the exhaust gas that comes out of the reactor (1); - a treatment and feeding line (11), arranged upstream of the reactor (1), to treat a process gas, obtained by mixing the make-up gas with the exhaust gas treated in the recovery and treatment line (10), and to feed the reduction area (2) of the reactor (1) with said process gas; wherein the recovery and treatment line (10) communicates downstream with said treatment and feeding line (11); wherein, in its end stretch, proximal to said treatment and feeding line (11), the recovery and treatment line (10) comprises a carbon dioxide removal device (50) to remove carbon dioxide from the exhaust gas, arranged upstream of a compressor (42) to compress the exhaust gas towards said treatment and feeding line (11).
C21B 13/00 - Making spongy iron or liquid steel, by direct processes
B01D 53/04 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
B01D 53/14 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by absorption
2.
CONTAINER, DEVICE AND METHOD FOR STORING OR PROCESSING PARTICULATE MATERIALS TO MINIMIZE OR ELIMINATE VIBRATIONS SUCH AS QUAKING OR SHAKING
A container with lower vibrations, such as quaking and shaking as well as noise effects, known also as hooting, honking or howling, and an effective and cost-competitive method and device to decrease such phenomena during the discharge of granular material particles from silos, hoppers, bins, reactors and in general containers for storing or processing such granular material particles. The container includes at least one baffle that is attached to the container wall, in the lower portion or at the bottom of the tapered discharge part of said container, protruding towards the central axis of its tapered discharge part. The baffle forms a stagnant zone in the bed of the granular material particles in contact with the container wall whereby the particles in that zone flow under the friction against other particles instead of the friction between the particles and the wall.
A plant for the production of briquettes of direct reduced iron (DRI) comprising: - a feeding line of direct reduced iron (DRI); - at least one briquetting machine (4, 4') for compacting the direct reduced iron (DRI) into briquettes, arranged downstream of said feeding line (1); wherein a carbon dosing device (5, 13), upstream of said at least one briquetting machine (4, 4'), is provided to add carbon into the direct reduced iron (DRI), whereby the carbon is compacted together with the direct reduced iron (DRI) in said at least one briquetting machine (4, 4'); wherein at least one heating device is provided, arranged upstream of said at least one briquetting machine (4, 4'), to heat the carbon; and wherein at least one recovery system (19) is provided, arranged upstream of said at least one briquetting machine (4, 4') to recover volatile substances which may be released from the carbon during heating by means of said at least one heating device.
C21B 13/00 - Making spongy iron or liquid steel, by direct processes
B01J 2/22 - Processes or devices for granulating materials, in generalRendering particulate materials free flowing in general, e.g. making them hydrophobic by pressing in moulds or between rollers
B30B 11/00 - Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses or tabletting presses
B30B 11/16 - Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses or tabletting presses using pocketed rollers, e.g. two co-operating pocketed rollers
A direct reduction plant (10) for a direct reduction of iron oxides to produce a DRI product, comprising a reactor (11), configured to being loaded with said iron oxides, a reduction circuit (19) fluidically connected to said reactor (11), a hydrogen generator (31) able to generate a make-up gas comprising hydrogen gas and configured to receive hydrocarbons as a feed and generate, in absence of oxidant agents, said make-up gas and a product comprising carbon in solid phase. The product comprising carbon is used, inside an electric arc furnace as required for the desired steel production or is mixed with the DRI product to produce HBI products or CBI products with a controlled quantity of carbon.
The present invention provides a reduction system and method that can be operated with any proportion of gaseous hydrogen-containing gases and gaseous hydrocarbon-containing gases having the possibility of continuing its operation, ensuring an high process availability and negligible loss of production, when the gaseous hydrogen-containing gas for any reason is not available and allow the substitution of the gaseous hydrogen-containing gas with a gaseous hydrocarbon-containing gas with minor adjustments in the plant operation. The reduction system of the invention is designed to be implemented in new and already built direct reduction plants to operate efficiently and has lower capital and operation costs.
A method for producing direct reduced iron is provided. The method includes circulating a first stream of spent reducing gas exiting a reactor in a reducing gas circuit through at least one carbon dioxide removal unit and a reducing gas heater and the reactor. The method also includes mixing the first stream with reducing gas containing heavier hydrocarbons than methane.
The present invention provides a reduction system and method that can be operated with any proportion of gaseous hydrogen-containing gases and gaseous hydrocarbon-containing gases having the possibility of continuing its operation, ensuring an high process availability and negligible loss of production, when the gaseous hydrogen-containing gas for any reason is not available and allow the substitution of the gaseous hydrogen-containing gas with a gaseous hydrocarbon-containing gas with minor adjustments in the plant operation. The reduction system of the invention is designed to be implemented in new and already built direct reduction plants to operate efficiently and has lower capital and operation costs.
A vessel for containing direct reduced iron (DRI), such as a reactor for the production of DRI, a bin or a hopper or other container for storing or feeding DRI to melting furnaces or briquetting machines, includes at least an upper zone, defined by a first lateral wall having a substantially cylindrical tubular shape, and a discharge zone, positioned below the upper zone and defined by a second lateral wall having a substantially truncated cone shape converging toward a lower discharge aperture. The second lateral wall has an internal surface at least partly lined by an internal lining.
Method for producing DRI that comprises circulating a first stream (F1) of spent reducing gas exiting a reactor (10) in a reducing gas circuit (20) through at least one carbon dioxide removal unit (38) and a reducing gas heater (42) and the reactor (10), and mix the first stream (F1) with reducing gas containing heavier hydrocarbons than methane.
A method and apparatus for producing direct reduced iron using a pre-treated make-up gas as a reducing agent in a direct reduced iron reactor are provided. The method involves pre-treating a stream of make-up gas containing heavy hydrocarbons by subjecting the stream to low temperature adiabatic reforming at a temperature between 300° C. and 600° C., prior to using the stream of make-up gas as a reducing agent for producing direct reduced iron. The method also involves adjusting the humidity content of the stream of make-up gas after the low temperature adiabatic reforming by bypassing the stream to selectively split it into a first part of the stream of make-up gas and a second part of the stream of make-up gas, subjecting the first part to water separation, and then mixing the first part with the second part to obtain a reducing stream to be sent to direct reduced iron production.
A container with lower vibrations, such as quaking and shaking as well as noise effects, known also as hooting, honking or howling, and an effective and cost-competitive method and device to decrease such phenomena during the discharge of granular material particles from silos, hoppers, bins, reactors and in general containers for storing or processing such granular material particles. The container includes at least one baffle that is attached to the container wall, in the lower portion or at the bottom of the tapered discharge part of said container, protruding towards the central axis of its tapered discharge part. The baffle forms a stagnant zone in the bed of the granular material particles in contact with the container wall whereby the particles in that zone flow under the friction against other particles instead of the friction between the particles and the wall.
A direct reduction system for a direct reduction of iron ore, comprising a reactor (1) having a reduction area (2) and being adapted to be loaded from above with said iron ore; a treatment and feeding line (11), to process the process gases, thus obtaining a reducing gas mixture, and feed said reducing gas mixture into the reduction area (2); a line (10) for recovering and treating an exhausted gas exiting the reactor (1), communicating upstream with the reactor (1) and downstream with said treatment and feeding line (11); wherein at least one bypass duct (30) is provided, adapted to divert at least one portion of reducing gas mixture from said treatment and feeding line (11) to said recovery and treatment line (10).
A vessel (10) for containing direct reduced iron (DRI), such as a reactor for the production of DRI, a bin or a hopper or other container for storing or feeding DRI to melting furnaces or briquetting machines, comprises at least an upper zone (11), defined by a first lateral wall (13) having a substantially cylindrical tubular shape, and a discharge zone (12), positioned below the upper zone (11) and defined by a second lateral wall (16) having a substantially truncated cone shape converging toward a lower discharge aperture (15). The second lateral wall (16) has an internal surface at least partly lined by an internal lining (22).
The invention provides containers with lower vibrations, such as quaking and shaking as well as noise effects, known also as hooting, honking or howling, and an effective and cost-competitive method and device to decrease such phenomena during the discharge of granular material particles from silos, hoppers, bins, reactors and in general containers for storing or processing such granular material particles. The invention comprises at least one baffle that is attached to the container wall, in the lower portion or at the bottom of the tapered discharge part of said container, protruding towards the central axis of its tapered discharge part. The baffle forms a stagnant zone in the bed of the granular material particles in contact with the container wall whereby the particles in that zone flow under the friction against other particles instead of the friction between the particles and the wall.
A method and apparatus for producing direct reduced iron, said method comprising producing direct reduced iron using a pre-treated make-up gas as a reducing agent in a direct reduced iron reactor (10), and wherein producing direct reduced iron is carried-out using a zero-reformer process in which catalytic reformation of the pre-treated make-up gas is carried-out "in situ" within the direct reduced iron reactor (10) such that the pre-treated make-up gas is subjected to no further catalytic reaction besides the catalytic reactions that occur inside said direct reduced iron reactor (10),characterized in thatsaid method comprises: - pre-treating a stream of said make-up gas containing heavy hydrocarbons by subjecting the stream of make-up gas to a low temperature adiabatic reforming at a temperature comprised between 300°C and 600°C, prior to using said stream of make-up gas as a reducing agent for producing direct reduced iron; - subjecting said pre-treated stream of make-up gas to adjusting humidity content of said stream of make-up gas after said low temperature adiabatic reforming by bypassing said stream of make-up gas to selectively split said stream into a first part (128) of said stream of make-up gas and a second part (130) of said stream of make-up gas and subjecting said first part (128) to a water separation and then mixing said first part (128) to said second part (130) to obtain a reducing stream (146) to be sent to direct reduced iron production.
A process for producing high-carbon DRI utilizing a syngas comprising hydrogen, carbon monoxide, carbon dioxide and a low content of methane, derived from the gasification of hydrocarbons, such as coal, in a reduction reactor comprising a reduction zone, a lower discharge zone and a transition zone between said reduction zone and said lower discharge zone, wherein a portion of the syngas comprising H2, CO and CO2 is treated in a methane-forming reactor to convert H2, CO and CO2 to CH4, whereby a carburizing gas stream containing more than about 20% of CH4 is produced. The carburizing gas is then introduced to the transition zone and/or to the lower discharge zone of said reactor to increase the carbon content in the DRI, mainly in the form of Fe3C. DRI with carbon content from 2% to 4.5 % may be produced by regulating the composition and flow rate of the carburizing gas.
A process for producing DRI with improved efficiency in a direct reduction plant comprising a reduction reactor, a heat exchanger, a gas humidifier, and a CO2 removal unit, wherein a coal-derived gas having a high content of CO is subject to CO conversion with H2O to H2 and CO2 resulting after passing through the CO2 removal unit in a reducing gas with an adequate composition for its use in the reduction reactor. A liquid water circuit is established to heat water in said heat exchanger using the heat content of the hot gas stream withdrawn from the reduction reactor and to evaporate hot water in the humidifier, for saturating at least a portion of the coal-derived gas stream with H2O by contact with said heated liquid water stream, thereby supplying all the H2O necessary for the CO-conversion reaction without needing additional steam injection.
Containing apparatus comprising a container (11) of material (12), and a discharge device (10) provided with at least a movement member (14) having a rotary shaft (15) inserted in said container (11) in through manner, and a plurality of blades (27) mounted radially on said rotary shaft (15) and defining corresponding containing cells (30) having the function of temporarily containing said material (12) in order to move it, due to the effect of the rotation of said rotary shaft (15) from a zone of said internal cavity (17a), disposed above said rotary shaft (15), toward a discharge aperture (24) of said container (11) disposed below said rotary shaft (15), wherein the rotary shaft (15) comprises at least two adjacent axial zones (A, B, C, D, E, F, G) along said axis of rotation (Y), and wherein in each of said axial zones (A, B, C, D, E, F, G) there is a plurality of said blades (27) that defines a corresponding wheel (26) with blades.
Containing unit of material (12) used in iron and steel process comprising a container (11) having at least one lateral wall (17) that defines an internal cavity (17a) and provided with a plurality of through lateral apertures (16); a discharge device (10) installed at least partly in said container (111) to divide said internal cavity (17a) into a first zone (13) disposed above said discharge device (10), and a discharge zone (31) disposed below said discharge device (10) and through which said material (12) is discharged, in a controlled manner, by said discharge device (10).
2-lean recycle reducing gas second effluent. The first and second effluents are fed to the reducing zone of the reduction reactor as the reducing gas reactant. The flow rate of at least the second of the two make-up gases is regulated to control the carbon content of the DRI produced.
A sealing device for a vessel to achieve a fluid-tight seal in an aperture made in the lateral wall of said vessel, into which aperture a shaft is inserted. The sealing device comprises first sealing means disposed in contact with the shaft in the zone of said aperture, and second sealing means, comprising a containing body and a flexible connection element. The first sealing means comprise a plurality of sealing rings, disposed coaxial to the shaft and in contact with the latter, and a containing tube to contain the sealing rings. The lateral wall of the vessel comprises an interface flange. A closing flange is connected to the interface flange and to a flanged end of the containing body by means of attachment means and is positioned in contact with the containing tube and with the flexible connection element to keep the first sealing means in a determinate axial position with respect to the shaft.
F16J 15/34 - Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member
F16J 15/18 - Sealings between relatively-moving surfaces with stuffing-boxes for elastic or plastic packings
B63B 9/00 - Methods of designing, building, maintaining, converting, refitting, repairing, or determining properties of, vessels, not otherwise provided for
F27D 99/00 - Subject matter not provided for in other groups of this subclass
22.
Method and apparatus for production of direct reduced iron (DRI) utilizing coke oven gas
Direct reduction process and plant for producing DRI comprising a reduction reactor and at least one reducing gas heater typically comprising a convective heating section and a radiant heating section for raising the reducing gas temperature to a level adequate for iron oxides reduction to metallic iron, typically above 850° C., wherein the reducing gas fed to the reduction reactor comprises a stream of reducing gas recycled from the reduction reactor and a make-up stream of coke oven gas containing carbon compounds which may form carbon deposits in the heating path of said heater, namely BTX and other complex carbon compounds. The heater is provided with means for feeding oxidizing agents, for example steam, steam and air and/or oxygen at predetermined heating tubes successively for eliminating the carbon deposits which may form inside the heating tubes of said heater without interrupting the operation of the plant. The make-up stream of cold COG can be combined with the recycled gas at a point in the gas heating path of the heater where the tubes have a skin wall temperature of at least 700° C., or when the mixture of recycled gas and COG is at a temperature above 700° C. for minimizing clogging or fouling of heating equipment.
2 for increasing its reduction potential and is heated to a temperature above 850° C. before being recycled thus defining a first gas flow path used during normal operation of the blast furnace. Uniquely, a second gas flow path for continued circulation of top gas selectively through the heater and a cooler during operation interruptions of the blast furnace allows time for gradual controlled cool down of the heater in a manner to avoid heat-shock damage to the tubular heater.
2 is at least partially removed for regenerating its reducing potential, with or without undergoing previous cleaning, is used for producing DRI. One inventive embodiment comprises producing DRI at high temperature giving advantageously higher productivity and energy savings when using hot DRI in an electric arc furnace lowering the capital and operational costs of steelmaking.
A direct reduction process producing DRI from iron oxide particles by reduction at a about 750 °C with a reducing gas mainly H2 and CO, that also includes CO2, H20, and methane, a the reduction reactor and the top gas effluent from the reduction reaction after cooling/scrubbing is split. The resulting first top gas portion with a first hydrocarbon-containing make-up gas passes through a catalytic reformer yielding an improved hot reducing gas first effluent. The second top gas portion passes through a CO2 removal unit and then with the second hydrocarbon-containing make-up gas passes through a heater yielding a hot CO2-lean recycle reducing gas second effluent. The first and second effluents are fed to the reducing zone of the reduction reactor as the reducing gas reactant. The flow rate of at least the second of the two make-up gases is regulated to control the carbon content of the DRI produced.
A sealing device for a vessel (12) to achieve a fluid-tight seal in an aperture (14) made in the lateral wall (18) of said vessel (12), into which aperture (14) a shaft (11) is inserted. The sealing device comprises first sealing means (24) disposed in contact with the shaft (11) in the zone of said aperture (14), and second sealing means, comprising a containing body (22) and a flexible connection element (43). The first sealing means (24) comprise a plurality of sealing rings (25), disposed coaxial to the shaft (11) and in contact with the latter, and a containing tube (32) to contain the sealing rings (25). The lateral wall (18) of the vessel (12) comprises an interface flange (17). A closing flange (37) is connected to the interface flange (17) and to a flanged end (23) of the containing body (22) by means of attachment means (47, 48) and is positioned in contact with the containing tube (32) and with the flexible connection element (43) to keep the first sealing means (24) in a determinate axial position with respect to the shaft (11).
A blast furnace system is used wherein the coke rate is decreased by recycling upgraded top gas from the furnace back into its shaft section (which upgraded top gas is heated in a tubular heater prior to being recycled). The top gas, comprising CO, CO2 and H2, is withdrawn from the upper part of the blast furnace; cooled and cleaned of dust, water, and CO2 for increasing its reduction potential and is heated to a temperature above 850°C before being recycled thus defining a first gas flow path used during normal operation of the blast furnace. Uniquely, a second gas flow path for continued circulation of top gas selectively through the heater and a cooler during operation interruptions of the blast furnace allows time for gradual controlled cool down of the heater in a manner to avoid heat-shock damage to the tubular heater.
2). The invention provides a more efficient method and plant comprising a reactor in which particulate material of iron ore comes into contact with a high temperature reducing gas to produce DRI, with lower investment and operating costs, avoiding the need for a fired heater for the reducing gas fed into the reduction reactor. The reducing gas is heated to a temperature above 700° C. in two steps, a first step at a temperature below about 400° C. to prevent the phenomenon of metal dusting, by exchange of sensible heat supplied by the stream of hot spent gas removed from the reduction reactor; and a second step by means of partial or total combustion with oxygen, maintaining the temperature of the combustion gas below the limits established by the construction materials of the combustion chamber.
C21B 13/02 - Making spongy iron or liquid steel, by direct processes in shaft furnaces
C21B 13/00 - Making spongy iron or liquid steel, by direct processes
B01D 53/14 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by absorption
A blast furnace where coke Is combusted with oxygen, Instead of air, and where a top gas comprising CO, CO2, H2, and without excess nitrogen is withdrawn from the upper part of the blast furnace, cleaned of dust, the H2/CO volume ratio adjusted to between 1.5 to 4.0 in a water shift reactor, water and CO2 are removed (increasing its reduction potential), heated to a temperature above 850°C, and fed back to the blast furnace above where iron starts melting (thereby Increasing the amount of metallic iron reaching the dead-man zone and decreasing the amount of coke used for reduction). Also carbon deposit problems caused by heating the CO-containing recycled gas are minimized by on-line cleaning of the heater tubes with steam without significantly affecting the reduction potential of the recycled reducing gas.
C10K 3/04 - Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide by catalytic treatment reducing the carbon monoxide content
30.
METHOD AND APPARATUS FOR PRODUCTION OF DIRECT REDUCED IRON (DRI) UTILIZING COKE OVEN GAS
Direct reduction process and plant for producing DRI comprising a reduction reactor and at least one reducing gas heater typically comprising a convective heating section and a radiant heating section for raising the reducing gas temperature to a level adequate for iron oxides reduction to metallic iron, typically above 850°C, wherein the reducing gas fed to the reduction reactor comprises a stream of reducing gas recycled from the reduction reactor and a make-up stream of coke oven gas containing carbon compounds which may form carbon deposits in the heating path of said heater, namely BTX and other complex carbon compounds. The heater is provided with means for feeding oxidizing agents, for example steam, steam and air and/or oxygen at predetermined heating tubes successively for eliminating the carbon deposits which may form inside the heating tubes of said heater without interrupting the operation of the plant. The make-up stream of cold COG can be combined with the recycled gas at a point in the gas heating path of the heater where the tubes have a skin wall temperature of at least 700°C, or when the mixture of recycled gas and COG is at a temperature above 700°C for minimizing clogging or fouling of heating equipment.
C01B 3/36 - Production of hydrogen or of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using oxygen or mixtures containing oxygen as gasifying agents
C10B 43/10 - Removing incrustations by burning out
A process for producing direct reduced iron (DRI) with lower emissions of CO2 to the atmosphere, in a direct reduction system comprising a direct reduction reactor to which iron oxides are fed in the form of pellets, lumps or mixtures thereof, wherein said iron oxides are caused to react with a reducing gas mainly composed of hydrogen and carbon monoxide at high temperature, and wherein said reducing gas is derived from the reformation of a hydrocarbon-containing gas, and wherein a first portion of the reducing gas stream effluent from said reduction reactor, which contains H2, CO, CO2 and H2O in various proportions, and which is cooled and cleaned in a cooler and which is combined with a gas containing hydrocarbons and said mixture passes through a catalytic reformer before being fed at high temperature to said reduction reactor. CO2 is removed from a portion of the gas stream effluent from said reduction reactor and the resultant gas stream is used as fuel in the reformer thus decreasing the amount of CO2 emitted to the atmosphere. The gas stream containing less CO2 but still containing CO to be used as fuel may further be reacted with water in a "shifter" reactor for converting said CO and H2O to CO2 and H2. In this way more CO2 may be removed from the fuel gas stream and therefore, the resultant fuel gas is mainly composed of hydrogen, further decreasing the amount of CO2 emitted to the atmosphere.
A process for producing direct reduced iron (DRI) from iron ores and reducing the cost and energy requirements of steelmaking, utilizing a gas produced from fossil fuels, containing sulfur compounds and BTX, wherein said gas is heated in a gas heater, wherein heat is transferred from a previously-heated solid material to the gas. The hot gas is caused to flow through a bed of DRI particles, iron oxides or equivalent material, outside of the reduction reactor, where said material adsorbs sulfur compounds and destroying the BTX. The gas resulting from this treatment, free from sulfur compounds and BTX, is combined with a reducing gas stream withdrawn from the reduction reactor after H20 and C02 have at least partially been removed for regenerating its reducing potential with or without undergoing a previous cleaning treatment.
An integrated steelmaking plant for merging continuous operation of a reduction reactor producing hot DRI with the batch operation of a DRI melting furnace(s). The reactor produces hot DRI for a DRI melting furnace or cold DRI continuously even when the DRI production exceeds the DRI consumption rate of the furnace or suffers long-term operational delays. The reduction reactor has a DRI cooling zone therein which is selectively operable for cooling DRI when the hot DRI produced in the reactor can't all be consumed by the DRI melting furnace and when the capacity of the DRI bin feeding the melting furnace is insufficient to accumulate additional hot DRI. No separate DRI cooling vessel plus its gas compressor and gas cooling-cleaning system is needed, thus decreasing capital and operational costs. This also permits a flexible and modular construction and operation of a steelmaking plant with high or low pressure reduction reactors.
C21B 13/00 - Making spongy iron or liquid steel, by direct processes
F27D 17/00 - Arrangements for using waste heatArrangements for using, or disposing of, waste gases
C21B 13/02 - Making spongy iron or liquid steel, by direct processes in shaft furnaces
B01D 53/14 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by absorption
B01D 53/22 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by diffusion
The present invention concerns a method and an apparatus for producing DRI (Direct Reduced Iron) utilizing a high-oxidation reducing gas containing carbon monoxide and hydrogen, derived directly or indirectly from the gasification of hydrocarbons or coal, with a high content of oxidants (H20 and CO2). The invention provides a more efficient method and plant comprising a reactor in which particulate material of iron ore comes into contact with a high temperature reducing gas to produce DRI, with lower investment and operating costs, avoiding the need for a fired heater for the reducing gas fed into the reduction reactor. The reducing gas is heated to a temperature above 700°C in two steps, a first step at a temperature below about 400°C to prevent the phenomenon of metal dusting, by exchange of sensible heat supplied by the stream of hot spent gas removed from the reduction reactor; and a second step by means of partial or total combustion with oxygen, maintaining the temperature of the combustion gas below the limits established by the construction materials of the combustion chamber.
A steelmaking plant including a pressurized direct reduction reactor for continuous production of hot direct reduced iron with a batch-melting furnace and a standby cooler, all three being capable of being situated side-by-side, with such DRI being able to be alternatively fed to the furnace or to the cooler. The furnace is selectively charged through a diverter valve by a pneumatic transport system with the hot DRI being entrained in a carrier gas fed into a receiving bin (having an upper DRI/gas disengagement space and a lower DRI buffer portion). A pressurized charge of the DRI accumulated in such disengaging/buffer bin is periodically fed down into a dosing/depressurization bin which in turn depressurizes the DRI and feeds a batch of DRI down into the furnace. Upon sensing that the buffer portion is full, the DRI is then pneumatically diverted to the cooler, such as during furnace maintenance shut down.
A method and apparatus for producing direct reduced iron (DRI), also known as sponge iron, by means of direct contact of iron oxides with a stream of recycled and regenerated hot reducing gases containing hydrogen and carbon monoxide. The invention provides a way for decreasing the uncontained emission of CO2 to the atmosphere produced by combustion of carbon-bearing fuels in the reducing gas heater by substituting, at least partially, a gas stream mainly composed of hydrogen in lieu of the usual carbon-bearing fuels. The hydrogen fuel stream, depleted of CO2 by means of a physical gas separation unit (which can be a PSA/VPSA type adsorption unit, a gas separation membrane unit or combination of PSA/VPSA unit and a gas separation membrane unit) is derived from at least a portion of a stream of regenerated reducing gases being recycled to the reduction reactor. The derived hydrogen fuel stream is combusted in the reducing gas heater and/or other thermal equipment in the reduction plant, thus decreasing the CO2 emissions directly to the atmosphere.
C21B 13/02 - Making spongy iron or liquid steel, by direct processes in shaft furnaces
B01D 53/04 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
B01D 53/14 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by absorption
An integrated steelmaking plant design is disclosed for efficiently merging the continuous operation of a reduction reactor producing hot DRI with the batch operation of at least one DRI melting furnace. The direct reduction reactor is adapted for producing hot DRI for its consumption in a DRI melting furnace or for producing cold DRI when the continuous production of DRI will exceed the DRI consumption rate of the melting furnace or when it suffers long-term operational delays. The reduction reactor has a DRI cooling zone within the same reactor vessel which is selectively operable for cooling the DRI in the same reactor vessel when the hot DRI produced in said reactor will not be consumed by the DRI melting furnace and when the capacity of the hot DRI bin feeding the melting furnace is insufficient to accumulate the amount of hot DRI which will not be consumed. The need of a DRI cooling vessel with its associated gas compressor and gas cooling and cleaning system is dispensed with therefore decreasing the capital and operational costs of said steelmaking plant. The invention also allows for a flexible and modular construction and operation of a steelmaking plant and is applicable to reduction reactors whether designed to operate at high or low pressure.
A process for reducing iron ore particles in a moving bed reduction reactor comprising an upper reduction zone and a lower discharge zone, wherein coke oven gas, preferably forming all the make-up for the reducing gas circulating through and reacting in the reduction zone, is first fed to the discharge (and, optionally, cooling) zone and thereafter, conditioned by the DRI in the lower zone, is withdrawn from the reactor and transferred externally into the recycle reducing gas for injection into the reduction zone; with the heavy hydrocarbons and other components of coke oven gas which cause fouling, corrosion, or deposits in the direct reduction plant being removed from coke oven gas by catalytic and/or adsorptive action of the DRI in the lower zone; preferably the gas flow rate of the coke oven gas and the externally transferred gas differs between about 100 and 200 NCM per ton of DRI produced.
A direct reduction process for producing direct reduced iron (DRI) in a reduction reactor having a reduction zone for reducing iron-oxides-containing particles, such as iron ore pellets, to DRI by reaction of said iron oxides with a high temperature reducing gas, and a cooling zone for lowering the temperature of the DRI produced in said reduction zone, wherein a stream of cooling gas, usually natural gas, is circulated through said cooling zone, a portion of said cooling gas is withdrawn from the cooling zone, cooled and cleaned in a gas cooler and a portion of the cooled gas is recycled to said reduction zone by means of an ejector utilizing the high-pressure natural gas make-up feed as the ejector's motive fluid. Using an ejector for recycling the cooling gas instead of using a mechanical compressor provides significant savings in electricity and in capital, operational and maintenance costs. A direct reduction plant having a DRI cooling zone which uses at least one ejector in recycling at least a portion of cooling gas to the cooling zone.
patents
