Patent Application
20230121974
The present invention generally relates to systems and methods for inputting thermal energy (heat) into fluids. In particular, the invention relates to tools and processes for optimizing energy efficiency and reducing greenhouse gas and particle emissions in heat-consuming industrial processes related to steel production carried out at high and extremely high temperatures.
Industry and governments have been combating to find technologies to achieve significant reductions in greenhouse gas (GHG) emission reduction. Heavy industrial processes such as steel production, have a key role to reach low emission targets set by companies, governments and international organizations. Electrification of these processes has been seen as a solution to reduce emissions. One of the obstacles for electrification was achieving high temperatures needed in steel production. By way of example, the core processes to melt and form steel require very high temperatures, such as within a range of about 850 to 1600 degrees Celsius (° C.). This sets strict requirements for energy sources and utilized technologies. In particular, while electricity already is used for some high temperature processes (such as in electric arc furnaces to melt steel, for example), in most cases, neither the technologies nor the economics are yet in place to do so.
A number of rotary solutions have been proposed for heating purposes. Thus, U.S. Pat. No. 11,098,725 B2 (Sanger et al) discloses a hydrodynamic heater pump device operable to selectively generate a stream of heated fluid and/or pressurized fluid. A mentioned hydrodynamic heater pump is designed to be incorporated in an automotive vehicle cooling system to provide heat for warming a passenger compartment of the vehicle and to provide other capabilities, such as window deicing and engine cooling. The disclosed device may also provide a stream of pressurized fluid for cooling an engine. Disclosed technology is based on friction; and, since the fluid to be heated is liquid, the presented design is not suitable for conditions involving extreme turbulence of gas aerodynamics.
U.S. Pat. No. 7,614,367 B1 (Frick) discloses a system and method for flamelessly heating, concentrating or evaporating a fluid by converting rotary kinetic energy into heat. Configured for fluid heating, the system may comprise a rotary kinetic energy generator, a rotary heating device, and a primary heat exchanger, all in closed-loop fluid communication. The rotary heating device may be a water brake dynamometer. The document discloses the use of the system for heating water in offshore drilling or production platforms. However, the presented system is not suitable for heating gaseous media, neither is it feasible for use with high and extremely high temperatures (due to liquid stability, vapor pressure, etc.).
Additionally, some rotary turbomachine-type devices are known to implement the processes of hydrocarbon (steam) cracking and aim at maximizing the yields of the target products, such as ethylene and propylene.
In this regard, an update in the field of technology related to design and manufacturing of efficient heating systems, in particular those suitable for high and extremely high temperature related applications, is still desired, in view of addressing challenges associated with raising temperatures of fluidic substances in efficient and environmentally friendly manner.
An objective of the present invention is to solve or to at least mitigate at least some of the problems arising from the limitations and disadvantages of the related art. One or more objectives are achieved by various embodiments of the methods for generation of a heated fluidic medium described herein, the rotary apparatuses and related uses as defined herein.
In an aspect, a method for steel production comprises generation of a heated fluidic medium by at least one rotary apparatus integrated into a steel production facility.
According to an embodiment, the method for steel production, which comprises generation of a heated fluidic medium by at least one rotary apparatus integrated into the steel production facility, improves energy efficiency or reduces greenhouse gas and particle emissions, or both.
In embodiments, the method for steel production comprises generation of a heated fluidic medium by virtue of at least one rotary apparatus integrated into a steel production facility, the at least one rotary apparatus comprising: a casing with at least one inlet and at least one exit, a rotor comprising at least one row of rotor blades arranged over a circumference of a rotor hub mounted onto a rotor shaft, and a plurality of stationary vanes arranged into an assembly at least upstream of the at least one row of rotor blades, wherein an amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium passes through the stationary vanes and the at least one row of rotor blades, respectively, whereby a stream of heated fluidic medium is generated; the method further comprises: conducting an amount of input energy into the at least one rotary apparatus integrated into the heat-consuming process facility, the input energy comprises electrical energy, supplying the stream of heated fluidic medium generated by the at least one rotary apparatus into the steel production facility, and operating said at least one rotary apparatus and said steel production facility to carry out steel production at temperatures essentially equal to or exceeding about 500 degrees Celsius (° C.).
In another aspect, a method is provided for inputting thermal energy into fluidic medium during steel production.
In an embodiment, the method comprises inputting thermal energy into a process or processes related to producing steel in a steel production facility, the method comprises generation of a heated fluidic medium by at least one rotary apparatus integrated into a steel production facility, the at least one rotary apparatus comprising a casing with at least one inlet and at least one exit, a rotor comprising at least one row of rotor blades arranged over a circumference of a rotor hub mounted onto a rotor shaft, and a plurality of stationary vanes arranged into an assembly at least upstream of the at least one row of rotor blades, the method further comprises: integrating the at least one rotary apparatus into the steel production facility configured to carry out process or processes related to production of steel at temperatures essentially equal to or exceeding about 500 degrees Celsius (° C.); conducting an amount of input energy into the at least one rotary apparatus integrated into the steel production facility, the input energy comprising electrical energy, and operating the at least one rotary apparatus integrated into the steel production facility such, that an amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium passes through the stationary vanes and the at least one row of rotor blades, respectively, whereby a stream of heated fluidic medium is generated.
In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one furnace within the steel production facility. In an embodiment, the at least one furnace is configured for steel making. In an embodiment, the furnace is configured to react steel pre-cursor materials and to form steel in the steel production facility. In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one furnace configured as a blast furnace for reducing iron ore to iron whereby molten iron is produced. Reduction of iron ore in the blast furnace may employ coke as reducing agent.
In some configurations, the at least one rotary apparatus can be operatively connected to at least one furnace configured as a basic oxygen furnace for oxygenating molten iron, whereby low-carbon steel is produced. In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one process unit configured as a furnace, a kiln or a reactor for direct reduction of iron ore to produce directly reduced iron (DRI), also referred to as “sponge iron”. During DRI production, iron ore is reduced to iron without melting it. Gas-based DRI processes take place in a process unit configured as a furnace, a kiln or a fluidized bed type reactor, in which the iron ore is reacted with hot reducing gas, such as hydrogen, natural gas or coke gas. Coke gas is a by-product of a coke-making process, also referred to as a coke plant off-gas or coke oven gas (COG). DRI processes may be followed with an appropriate melting procedure (e.g. electric art melting) to produce steel.
In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one sintering plant and/or a pellet plant configured to sinter iron ore into iron ore sinter and/or pellets. In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one furnace or a coke plant configured for coking coal into coke in the steel production facility. In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one post-processing unit configured for post-processing of a steel product via any one of: heat treatment, carburizing, casting and/or rolling. In embodiments, the method comprises operating the at least one rotary apparatus operatively connected to at least one reactor or a series of reactors configured for the endothermic reactions in steel production, in particular, for the endothermic reactions of off-gases generated in steel production. Any combination of the embodiments described above can be conceived.
As used herein, a “furnace” refers to an apparatus in which heat is produced or added as part of a combustion process. The furnace may be a blast furnace, a cupola furnace, a pot and tank furnace, a shaft furnace, a regenerative furnace, or another furnace depending on the needs of the specific application. The decision to recite “furnace” to the exclusion of any specific type of furnace or another apparatus for combustion is in the interest of brevity only and is not intended to limit the scope of the invention.
In embodiment, the method comprises generation of the fluidic medium heated to the temperature essentially equal to or exceeding about 500 degrees Celsius (° C.), or to the temperature essentially equal to or exceeding about 1200° C., or to the temperature essentially equal to or exceeding about 1700° C.
In embodiment, the method comprises adjusting velocity and/or pressure of the stream of fluidic medium propagating through the rotary apparatus, to produce conditions, at which the stream of the heated fluidic medium is generated.
In embodiments, in said method, the heated fluidic medium is generated by at least one rotary apparatus comprising two or more rows of rotor blades sequentially arranged along the rotor shaft.
In an embodiment, in said method, the heated fluidic medium is generated by at least one rotary apparatus further comprising a diffuser area arranged downstream of the at least one row of rotor blades, the method furthers comprises operating the at least one rotary apparatus integrated into the steel production facility such, that an amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium successively passes through the stationary guide vanes, the at least one row of rotor blades and the diffuser area, respectively, whereby a stream of heated fluidic medium is generated. The diffuser area may be configured with or without stationary vanes.
In embodiments, in said method, the amount of thermal energy added to the stream of fluidic medium propagating through the rotary apparatus is controlled by adjusting the amount of input energy conducted into the at least one rotary apparatus integrated into the steel production facility.
In embodiments, the method further comprises arranging an additional heating apparatus downstream of the at least one rotary apparatus and introducing a reactive compound or a mixture of reactive compounds to the stream of fluidic medium propagating through the rotary apparatus and/or through said additional heating apparatus, whereupon the amount of thermal energy is added to said stream of fluidic medium through exothermic reaction(s). In embodiment, the reactive compound or a mixture of reactive compounds is introduced to the stream of fluidic medium preheated to a predetermined temperature. In embodiment, the reactive compound or a mixture of reactive compounds is introduced to the stream of fluidic medium preheated to a temperature essentially equal to or exceeding about 1700° C. In embodiment, preheating of the stream of fluidic medium to the predetermined temperature is implemented in the rotary apparatus.
In an embodiment, the method comprises generation of the heated fluidic medium by at least two rotary apparatuses integrated into the steel production facility, wherein the at least two rotary apparatuses are connected in parallel or in series. In embodiments, the method comprises generation of the heated fluidic medium by at least two sequentially connected rotary apparatuses, wherein the stream of fluidic medium is preheated to a predetermined temperature in at least a first rotary apparatus in a sequence, and wherein said stream of fluidic medium is further heated in at least a second rotary apparatus in the sequence by inputting an additional amount of thermal energy into the stream of preheated fluidic medium propagating through said second rotary apparatus. In an embodiment, in said method, in at least the first rotary apparatus in the sequence, the stream of fluidic medium is preheated to a temperature essentially equal to or exceeding about 1700° C. In an embodiment, in said method, the additional amount of thermal energy is added to the stream of fluidic medium propagating through said at least second rotary apparatus in the sequence by virtue of introducing the reactive compound or a mixture of reactive compounds into said stream. In an embodiment, the method comprises introducing the reactive compound or a mixture of reactive compounds into a process or processes related to the production of steel. Such process or processes can for example be implemented in a furnace configured for steel making.
In an embodiment, in said method, the heated fluidic medium generated by the at least one rotary apparatus is selected from the group consisting of a feed gas, a recycle gas, a make-up gas, and a process fluid. In an embodiment, in said method, the fluidic medium that enters the rotary apparatus is an essentially gaseous medium.
In an embodiment, the method comprises generation of the heated fluidic medium in the rotary apparatus. In embodiments, in said method, the fluidic medium to be heated in the rotary apparatus comprises any one of: air, steam (H2O), nitrogen (N2), hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), or any combination thereof. Any other gas can be utilized where appropriate. In an embodiment, in said method, the fluidic medium to be heated in the rotary apparatus is a recycle gas recycled from off-gases, such as exhaust gases, generated from the reacting steel pre-cursor materials, such as iron or iron ore and carbon, during the steel manufacturing process. In embodiments, the pre-cursor materials hence include carbon and iron. The pre-cursor(s) may be iron oxide so that the method is effective to produce iron from the iron oxide. The pre-cursor(s) may be coal so that the method is effective to produce coke from the coal.
In embodiment, the method further comprises generation of the heated fluidic medium, such as gas, vapor, liquid, and mixtures thereof, and/or heated solid materials, outside the rotary apparatus through a process of heat transfer between the heated fluidic medium generated in the rotary apparatus and any one of the above-mentioned substances bypassing the rotary apparatus.
In embodiments, the method further comprises supplying the heated fluidic medium generated by the at least one rotary apparatus or in the at least one rotary apparatus into at least one heat-consuming unit within the steel production facility, the heat-consuming unit being provided as any one of: (i) a furnace, a kiln or a reactor configured for making steel, (ii) a sintering/pellet plant configured to sinter iron ore into iron ore sinter/pellets, (iii) a coke plant configured to coke coal into coke, (iv) a post-processing unit configured for post-processing of a steel product via any one of: heat treatment, upgrading the steel product with a source of carbon (carburizing), casting and/or rolling, (v) a reactor or a series of reactors configured for the endothermic reactions in steel production, in particular, for the endothermic reactions of off-gases generated in steel production, or (vi) any combination thereof.
In embodiments, the process of making steel (i) involves production of molten iron in a blast furnace or production of direct reduced iron (DRI) in a process unit, such as a furnace, a kiln or a reactor.
In embodiments, the method further comprises supplying the heated fluidic medium generated by the at least one rotary apparatus or in the at least one rotary apparatus into at least one heat-consuming unit within the steel production facility, the heat-consuming unit being provided as any one of: a heater, a burner, an oven, an incinerator, a dryer, a conveyor device, or a combination thereof. In some configurations, the method may further include supply of heated fluidic medium to a (pre)heater configured for (pre)heating of steelmaking ladles (vessels used to transport and pour out molten metal).
In embodiment, the method further comprises increasing pressure in the stream of fluidic medium propagating through the rotary apparatus.
In embodiment, in said method, the amount of electrical energy conducted as the input energy into the at least one rotary apparatus integrated in the steel production facility is within a range of about 5 percent to 100 percent.
In embodiment, in said method, the amount of electrical energy conducted as the input energy into the at least one rotary apparatus integrated in the steel production facility is obtainable from a source of renewable energy or a combination of different sources of energy, optionally, renewable energy.
In embodiment, in said method, the at least one rotary apparatus is utilized to balance variations, such as oversupply and shortage, in the amount of electrical energy (obtained through supply and/or production, for example), optionally renewable electrical energy, by virtue of being integrated, into the steel production facility, together with an at least one non-electrical energy operable heater device.
In another aspect, a steel production facility is provided, said steel production facility comprising at least one rotary apparatus configured to generate a heated fluidic medium and at least one heat-consuming unit configured to carry out a process of processes related to steel production, in accordance with the present disclosure.
In an embodiment, the steel production facility comprises at least one rotary apparatus configured to generate a heated fluidic medium and at least one heat-consuming unit configured to carry out a process of processes related to steel production, the at least one rotary apparatus comprising: a casing with at least one inlet and at least one exit, a rotor comprising at least one row of rotor blades arranged over a circumference of a rotor hub mounted onto a rotor shaft, and a plurality of stationary vanes arranged at least upstream of the at least one row of rotor blades, wherein the at least one rotary apparatus is configured to operated such that an amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium passes through the stationary vanes and the at least one row of rotor blades respectively, whereby a stream of heated fluidic medium is generated, and wherein said at least one rotary apparatus is configured to receive an amount of input energy, the input energy comprising electrical energy, and to generate a heated fluidic medium for inputting thermal energy into at least one heat-consuming unit configured to carry out a process or processes related to steel production at temperatures essentially equal to or exceeding about 500 degrees Celsius (° C.).
In an embodiment, the at least one heat-consuming unit is a furnace configured for steel making, and the at least one rotary apparatus is connected to said furnace within the steel production facility. In an embodiment, the at least one heat-consuming unit is a furnace configured to react steel pre-cursor materials to produce steel, and the at least one rotary apparatus is connected to said furnace within the steel production facility.
In embodiments, the at least one heat-consuming unit provided within the steel production facility is any one of: (i) a blast furnace for reducing iron ore to iron, whereby molten iron is produced, (ii) a sintering/pellet plant configured to sinter iron ore into iron ore sinter/pellets, (iii) a furnace, a kiln or a reactor configured for direct reduction of iron ore to direct reduced iron (DRI), (iv) a coke plant configured to coke coal into coke, (v) a post-processing unit configured for post-processing of a steel product via any one of: heat treatment, carburizing, casting and/or rolling, (vi) a reactor or a series of reactors configured for the endothermic reactions in steel production, in particular, for the endothermic reactions of off-gases generated in steel production, or (vii) any combination thereof. In embodiments, the at least one rotary apparatus is connected to and/or integrated into any one of units (i)-(vii).
In embodiments, the at least one heat-consuming unit is configured as any one of: a heater, a burner, an oven, an incinerator, a dryer, a conveyor device, or a combination thereof, and the at least one rotary apparatus is connected to any one of these heat-consuming units or any combination thereof within the steel production facility.
In embodiments, in said steel production facility, the at least one rotary apparatus comprises two or more rows of rotor blades sequentially arranged along the rotor shaft. In an embodiment, stationary vanes arranged into the assembly upstream of the at least one row of rotor blades are configured as stationary guide vanes. In an embodiment, the at least one rotary apparatus further comprises a diffuser area arranged downstream of the at least one row of rotor blades. The diffuser area may be configured with or without stationary diffuser vanes. In some configurations, vaned diffuser may be implemented as a plurality of stationary vanes arranged into an assembly downstream of the at least one row of rotor blades.
In an embodiment, the at least one rotary apparatus provided within said steel production facility is further configured to increase pressure in the fluidic stream propagating therethrough.
In an embodiment, the at least one heat-consuming unit configured to carry out steel production is a furnace configured to react steel pre-cursor materials to produce steel
In some configurations, the at least one rotary apparatus provided within said steel production facility is configured to implement a fluidic flow, between the inlet and the exit, along a flow path established in accordance with any one of: an essentially helical trajectory formed within an essentially toroidal-shaped casing; an essentially helical trajectory formed within an essentially tubular casing, an essentially radial trajectory, and along the flow path established by virtue of the stream of fluidic medium in the form of two spirals rolled up into vortex rings of right and left directions.
In a further aspect, an assembly is provided and comprises at least two rotary apparatuses according to some previous aspect, said rotary apparatuses being connected in parallel or in series.
In a further aspect, an arrangement is provided and comprises at least one rotary apparatus according to some previous aspect, said at least one rotary apparatus being connected to at least one furnace.
In a further aspect, a steel production facility is provided and is configured to implement a steel production process through a method according to some previously defined aspects and embodiments; and it comprises at least one rotary apparatus according to some previous aspect.
The utility of the present invention arises from a variety of reasons depending on each particular embodiment thereof.
Overall, embodiments offer an electrified rotary fluid heater to provide high temperature fluids, such as gases, to be used in the production of steel instead of fuel-fired heaters, for example. The presented method enables inputting thermal energy into furnaces used in steel production or steel pre-cursor production operating at high- and extremely high temperatures, such as temperatures generally exceeding 500° C. The invention offers apparatuses and methods for heating the fluidic substances to the temperatures within a range of about 500° C. to about 2000° C., i.e. the temperatures used in steel production.
The invention further offers the methods for thermally treating off-gases generated at various stages of steel making, wherein thermally treated off-gases can further be used for syngas production in endothermic reactor(s) integrated into the steel production facility, according to the embodiments.
Steel production typically employs utility with high demand for thermal energy and hence, for heat consumption, such as fired heaters, for example. Said heat-consuming utilities are used to heat fluids to the temperatures needed for the steel production process. The invention presented herewith enables replacing conventional heat-consuming utilities, such as fuel fired heaters, by a rotary apparatus. In the method, the advantages accompanied by replacing fired heaters with the rotary apparatus include at least:
In embodiments, the rotary apparatus can be used to replace conventional fired heaters or process furnaces for direct or indirect heating in steel production. Traditionally such heat has been mainly produced through burning of fossil fuels leading to significant CO2 emissions. Replacing fossil fuels with wood or other bio-based materials has significant resource limitations and other significant environmental implications such as sustainable land use. With the increased cost-efficiency of renewable electricity, namely the rapid development of wind and solar power, it is possible to replace fossil fuel firing with the rotary apparatus powered with renewable electricity leading to significant greenhouse gas emission reductions. The rotary apparatus allows electrified heating of fluids to temperatures up to 1700° C. and higher. Such temperatures are difficult or impossible to reach with current electrical heating applications.
The rotary apparatus can be used for direct heating of process gases, inert gases, air or any other gases or for indirect heating of process fluids (liquid, vapor, gas, vapor/liquid mixtures etc.). Heated fluid generated in said rotary apparatus can be used for heating any one of gases, vapor, liquid, and solid materials. In particular, the rotary apparatus can be used for direct heating of recycled gas recycled from exhaust gases generated from the reacting of iron or iron ore and carbon during steel production. The rotary apparatus can at least partly replace- or it can be combined with (e.g. as pre-heater) multiple types of furnaces, heaters, kilns, gasifiers, and reactors that are traditionally fired or heated with solid, liquid or gaseous fossil fuels or in some cases bio-based fuels, including furnaces used in steel production. Heated gases can be flammable, reactive, or inert and can be recycled back to the rotary apparatus. In addition to heating, the rotary apparatus may act as combined blower and heater allowing to increase pressure and to recycle gases.
Heated fluids, such as gases, can be used in a variety of applications. A heated object can be a solid material, liquid or gas, which gas further takes part in a number of reactions or is used as a heating media. Hence, hot gases can be used for heating solid materials like in steel production factories. Furthermore, the rotary apparatus(es) 100 can be applied, within the steel production process(es)/facilities, for heat provision and fluidization in fluidized bed applications, including, but not limited with: drying of solids, solid-catalysed reactors with gaseous reactants, iron ore reduction, and carburizing.
The invention enables the reduction of greenhouse gas (CO, CO2, NOR) and particle emissions when replacing fired heaters. By using the rotary apparatus, it is possible to have closed or semi-closed heating loops for processes, and to improve energy efficiency of the processes by reducing heat losses through flue gas. In conventional heaters, flue gases can be recycled only partly.
Additionally, the present solution enables improved optimization of the temperature difference(s) in the heat exchangers in indirect heating.
The invention further provides for flexibly using electrical energy, such as electrical energy obtainable from renewable sources. Production of renewable energy varies on daily basis and even on hourly basis. The invention allows for balancing renewable electricity production by integration of the rotary apparatus disclosed herewith with conventional fuel-operated (fuel-fired) heaters to provide heat to the steel production process, and particularly to the high temperature mixing of iron and carbon, for example.
The invention further enables a reduction in the on-site investment costs as compared to traditional fossil fired furnaces.
The expression “a number of” refers hereby to any positive integer starting from one (1), e.g. to one, two, or three. The expression “a plurality of” refers hereby to any positive integer starting from two (2), e.g. to two, three, or four. The terms “first” and “second”, are used hereby to merely distinguish an element from another element without indicating any particular order or importance, unless explicitly stated otherwise.
The term “gasified” is utilized hereby to indicate matter being converted into a gaseous form by any possible means.
Different embodiments of the present invention will become apparent by consideration of the detailed description and accompanying drawings.
Detailed embodiments of the present invention are disclosed herein with the reference to accompanying drawings.
The heat-consuming process facility 1000, 3000, 4000 is a facility configured to carry out a heat-consuming industrial process or processes 101 at temperatures essentially equal to or exceeding 500 degrees Celsius (° C.). Facility 1000, 3000, 4000 can be represented with an industrial plant, a factory, or any industrial system comprising equipment designed to perform the above-mentioned heat-consuming industrial process(es). The heat-consuming industrial process or processes 101 may be represented with any one of: sintering or pelletising iron ore to produce sinter or pellets (rf. 317, FIGS. 3A, 3C, 3F, Example 2), coking of coal to form coke (rf. 308,
In embodiments, facility 1000, 3000, 4000 is configured to carry out the heat-consuming industrial process(es) at temperatures within a range of 500-1700° C. In embodiments, facility 1000, 3000, 4000 is configured to carry out the heat-consuming industrial process(es) which start at temperatures essentially within a range of about 800-900° C. or higher. In embodiments, facility 1000, 3000, 4000 is configured to carry out the heat-consuming industrial process(es) at temperatures essentially equal to—or exceeding 1000° C. In embodiments, facility 1000, 3000, 4000 is configured to carry out the heat-consuming industrial process(es) which start at temperatures essentially within a range of about 1100-1200° C. or higher. In embodiments, the facility is configured to carry out the heat-consuming industrial process(es) at temperatures essentially equal to—or exceeding 1200° C. In embodiments, the facility is configured to carry out the heat-consuming industrial process(es) at temperatures within a range of about 1300-1700° C. In embodiments, the facility is configured to carry out the heat-consuming industrial process(es) at temperatures essentially equal to—or exceeding 1500° C. In embodiments, the facility is configured to carry out the heat-consuming industrial process(es) at temperatures essentially equal to—or exceeding 1700° C. In some embodiments, the facility can be configured to carry out industrial process(es) at temperatures that exceed 1700° C., such as at 2000° C. or higher, such as within a range of about 1700° C. to about 2500° C. The facility can be configured to carry out industrial process(es) at about 1700° C., at about 1800° C., at about 1900° C., at about 2000° C., at about 2100° C., at about 2200° C., at about 2300° C., at about 2400° C., at about 2500° C., and at any temperature value falling in between the above-mentioned temperature points. It should be pointed out that facility 1000, 3000, 4000 is not excluded from carrying out of at least a part of industrial processes at temperatures below 500° C.
Further description utilizes reference numbers as illustrated on
Iron ore reduction to iron typically takes place in a furnace, such as blast furnace, but it can also be accomplished in gas-solid process units, such as kilns or (fluidized bed) reactors. The latter are typically used in production of so-called direct reduced iron (DRI) or sponge iron. In the mentioned appliances, iron oxide ore is reduced to iron through the removal of oxygen. Oxygen removal from iron oxide ore may be accomplished by heating the iron oxide ore in a carbon monoxide/hydrogen rich atmosphere, either through the introduction of carbon monoxide and hydrogen gas, or by the addition of a source of carbon monoxide and hydrogen, such as coal or coke.
In some embodiments, in the blast furnace, iron oxide ore is reduced to iron with help of coke. Carbon in coke is oxidised to CO and CO2. When coke is used as a reductant, the Redox reaction is exothermic, and the blast furnace can operate in an autothermal mode where no additional heat source is needed to maintain the high reaction temperature. In modern furnaces, additional fuel like natural gas can be fed into furnace to boost the temperature higher and to increase the reduction efficiency since the natural gas primarily comprises methane that acts as a reductant. Another means to increase the efficiency is through so-called hot blast, which is air pre-heated to a temperature within a range between about 900° C. to about 1300° C. that provides a boost for temperature by incinerating coke or coal directly.
Blast furnace off-gas is typically a mixture rich in nitrogen and carbon dioxide, which are not flammable. The rest consists of carbon monoxide, which has a fairly low heating value, and hydrogen. Much of the CO2 emissions arising from steel manufacturing originate from the blast furnace heating of iron and coke and are emitted in the form of furnace off-gas. There is a high interest in reducing CO2 emissions in steel industry; one way to do it is to introduce additional renewable hydrogen into the off-gas stream and perform a reverse water-gas shift (RWGS) reaction to convert CO2 and hydrogen into CO and water. CO can then be coupled with additional hydrogen to yield a mixture of CO and H2 called synthetic gas (syngas). Syngas can be used as a raw material for methanol or Fischer-Tropsch hydrocarbons that have value as raw material for chemical industry. The syngas may also be recycled in the system to serve as a reductant of iron oxide into iron.
One challenge with the RWGS reaction is that reaction equilibrium is favourable to products only in temperatures above 1000° C. Heating feed gas mixture to such temperatures typically requires fossil-fuel fired furnaces that produce CO2 emissions and partially neutralise the benefits in applications such as blast furnace off-gas modification to syngas. The rotary apparatus of the present invention can be applied to bring the feed to reaction temperature of about 1000-1200° C. without additional CO2 emissions. Adding extra hydrogen into the reaction mixture helps with reaching desired product composition, as hydrogen pushes the equilibrium CO2 concentration down. This may allow operation of an RWGS reactor at temperatures below 1000° C. but still requires temperatures above 650-700° C. and leads to increase in reactor size due to high hydrogen recycle. The reaction requires a catalyst and is mildly endothermic, so product temperature is lower than feed temperature and additional rotary apparatus/catalyst cycles or product recycling may be required to reach desired reaction equilibrium.
An alternative for RWGS is dry reforming, where methane reacts with CO2 in the blast furnace off-gas to produce hydrogen and carbon monoxide (CO). A similar high temperature, catalytic and endothermic reaction scheme applies to dry reforming as well, but methane as raw material is easier to access than green hydrogen. The resulting syngas is higher in CO/H2 ratio than that of RWGS, which may limit its applications.
Another way to mitigate CO2 emission from steel industry is to use hydrogen instead of coal as a reducing agent. Unlike coke reduction, hydrogen reduction is endothermic reaction and requires additional heat input to maintain the reaction temperature. This additional heat input typically comes from excess hydrogen that is incinerated in the blast furnace. Application of the rotary apparatus in iron ore reduction with hydrogen would be to supply this additional heat by heating the hydrogen to the reaction temperature or above and to recycle gaseous reaction products, mainly water and unreacted hydrogen, at least partially back to the reduction operation for optimal heat recovery. In direct iron reduction (DRI) applications using hydrogen as reducing agent, hydrogen gas heated in the rotary apparatus can be used in gas-solid process units, such as kilns or (circulating) fluidized bed type reactors, where solid iron ore is contacted with hot hydrogen gas. Additionally or alternatively, air or other gas heated in the rotary apparatus can be used as a heat transfer medium to indirectly (pre)heat solid iron ore feedstocks in a fluidized bed system, for example (rf. Example 7).
Further application of the rotary apparatus in steel industry is hot rolling where the rotary apparatus would recycle hot air or nitrogen around the steel sheets to bring them above recrystallisation temperature. Recycling the hot air or nitrogen would improve the energy efficiency
Steel manufacturing has high thermal (heat) energy demand and consumption and, in conventional solutions (viz. outside the heat integration scheme 1000 presented herewith), produce considerable industrial emissions such as carbon dioxide into the atmosphere. The present disclosure offers apparatuses and methods for inputting thermal energy into steel manufacturing, 101 which has high heat energy demand, whereby energy efficiency in said process can be markedly improved or the amount of air pollutants released into the atmosphere is reduced or both. Layout 1000 (
In embodiments, the method comprises generation of a heated fluidic medium such as air or oxygen or fuel enriched air by virtue of a rotary heater unit 100 comprising or consisting of at least one rotary apparatus, hereafter, the apparatus 100. For the sake of clarity, the rotary heater unit is designated in the present disclosure by the same reference number, 100, as the rotary apparatus. The rotary heater unit is preferably integrated into the process facility 1000. In an embodiment, the heated fluidic medium is produced by the at least one rotary apparatus, however, in some embodiments a plurality of rotary apparatuses may be used in series or in parallel.
The rotary apparatus 100 can be provided as a standalone apparatus or as a number of apparatuses arranged in series (in sequence) or in parallel. One or more apparatuses may be connected to a common heat-consuming unit 101, such as a furnace, for example. Connection may be direct or through a number of heat exchangers.
The heat-consuming unit(s) 101 is/are provided as one or furnaces or other utilities adapted to implement processes related to manufacturing of steel. In some configurations, thermal energy of the fluid, such as gas, heated in 100 is used to run endothermic reactions in the unit 101 (rf. description to
The heat-consuming unit(s)/utility(/ies) 101 for steel manufacture is typically one or more furnaces. In some configurations, a number of rotary apparatus units can be connected to several heat-consuming utilities. Different configurations may be conceived, such as n+x rotary apparatuses connected to n utilities (e.g. furnaces), wherein n is equal to or more than zero (0) and x is equal to or more than one (1). Thus, in some configurations, the facility 1000 and, in particular, the rotary heater unit 100, may comprise one, two, three or four parallel rotary apparatus units connected to the common heat-consuming unit, such as a furnace, for example; the number of rotary apparatuses exceeding four (4) is not excluded. When connecting, in parallel, a number of rotary apparatuses to the common heat-consuming unit, one or more of said apparatuses 100 may have different type of drive engine, e.g. the electric motor driven reactor(s) can be combined with those driven by steam turbine, gas turbine and/or gas engine.
In an embodiment, an amount of input energy E1 is conducted into the at least one rotary apparatus 100 integrated, as a (rotary) heater unit, into the process facility 1000. The input energy E1 preferably comprises electrical energy. In embodiments, the amount of electrical energy conducted as the input energy into the at least one rotary apparatus integrated in the heat-consuming process facility is provided within a range of about 5 to about 100 percent, preferably, within a range of about 50 to about 100 percent. Thus, the amount of electrical energy conducted as the input energy into the at least one rotary apparatus integrated in the heat-consuming process facility can constitute any one of: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 percent (from the total energy input), or any intermediate value falling in between the above indicated points.
Electrical energy can be supplied from external or internal source. In practice, electrical input energy E1 supplied into the apparatus can be defined in terms of electric power, the latter being defined as a rate of energy transfer per unit time (measured in Watt).
Particulars of some embodiments of the invention, as implemented in the facility layout of
The rotary apparatus 100 is configured to receive a feed stream 1, hereafter, the feed 1. Overall, the feed 1 can comprise or consist of any fluid, such as liquid or gas or a combination thereof, provided as a pure component or a mixture of components. The feed can be a feedstock gas, a process gas, a make-up gas (a so-called replacement/supplement gas), and the like. Gaseous feed can include inert gases (air, nitrogen gas, and the like) or reactive, e.g. oxygen, flammable gases, such as hydrocarbons, or any other gas like hydrogen and ammonia. Selection of the feed is process-dependent; that is, the nature of the heat-consuming process 101 (and indeed a specific industry/an area of industry said heat-consuming process 101 is assigned to) implies certain requirements and/or limitations on the selection of feed substance(s). Therefore, in the manufacture of steel, the feed 1 is typically air or a combination of air and additional oxygen or also combustion fuel. In the coking of coal to form coke, the feed 1 is typically an oxygen-free gas, such as pre-heated carbon dioxide or an inert gas. Additionally or alternatively, feed 1 may include any one of: (water) steam, nitrogen (N2), hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4).
It is preferred that the feed 1 enters the apparatus 100 in essentially gaseous form. Preheating of the feed or conversion of liquid or essentially liquid feed(s) into a gaseous form can be performed in an optional preheater unit 102 configured as a (pre)heater apparatus or a group of apparatuses. In the preheater unit 102, the feed stream(s) originally provided in a gaseous form (e.g. the process gas or gases) can be further heated (e.g. superheated). In the preheater unit 102, the feed 1 can be vaporized if not already in gas form and optionally superheated.
The preheater unit 102 can be any conventional device/system configured to provide heat to fluidic substance. In some configurations, the preheater unit 102 can be a fired heater (viz. a direct-fired heat exchanger that uses hot combustion gases (flue gases) to raise the temperature of a fluidic feed, such as a process fluid, flowing through the coils arranged inside the heater). Additionally or alternatively, the preheater unit 102 can be configured to exploit energy made available by the other units in the heat-consuming facility (for example by extracting thermal energy from hot stream 13 arriving from heat recovery). The preheater unit 102 can thus be configured to utilize other steam streams, as well as electricity and/or waste heat streams (not shown).
Depending on a heat-consuming process and related equipment, which in this embodiment is steel production, the feed stream 1 used to produce the heated fluidic medium, such as air, by virtue of the rotary heater unit (the apparatus 100) comprises a virgin feed (fresh feed) and/or recycle stream(s). Hence, the feed 1 may consist of any one of fresh feed, recycle (fluidic) stream, and a mixture thereof. Stream 2 representing (pre)heated feed may include, in addition to feed 1, all recycle streams, such as those arriving from a purification section 105 and/or a heat recovery section 104.
In the rotary heater unit/the rotary apparatus 100, the temperature is raised to a level which is required by the heat-consuming process 101 or to a maximum level achieved by the rotary apparatus. In an event the temperature rise achieved by the rotary apparatus 100 is not sufficient for the heat-consuming process and/or if, for example, the temperature of the fluid needs to be raised again after it has transferred its heat to the heat-consuming process, further temperature rise can be achieved by virtue of arranging additional heater units (100B, 103), further referred to as “booster” heater(s), downstream of the rotary heater unit 100 (100A); rf. description to
In heat-consuming processes, such as the steel production described herein, the main sources of heat consumption are heating of working fluids and/or associated equipment and endothermic reactions (reactions that require external energy to proceed). In some applications it is feasible to recover heat from heat-consuming processes 101. Heat recovery section is indicated on
Heat recovery may be arranged through collecting gases exiting the process unit 101 and recycling these gases to the preheater unit 102 and/or the rotary apparatus 100. The heat recovery installation 104 may be represented with at least one heat exchanger device (not shown). Heat exchangers based on any appropriate technology can be utilized. Heat recovery may be optional for heating feed gas if the heat is consumed elsewhere or if it is not possible to recover heat due to safety- or any other reason.
In the facility layout 1000, the heat recovery unit 104 can be arranged before and/or after the preheater 102. In the latter configuration, the heat recovery unit 104 is arranged to recover heat from the hot fluidic medium (stream 5) flowing from the steel manufacturing process 101, which may be further utilized to heat the feed stream 1 and recycle stream 11. On the other hand, when the heat recovery unit 104 is arranged before the preheater 102, the feed 1 is first led to the unit 104 (as stream 12) and then returned to preheating 102 as stream 13. In such a case, unit 104 acts as a first preheater.
In some instances, gases require purification, e.g. from dust and fine particles, before being directed to heat recovery. Purification can be done by a series of filters, for example, arranged before the heat recovery section 104 (not shown). Additionally or alternatively the gases exiting the process unit 101 may be directed to a purification unit 105 (bypassing the unit 104), and, after purification, returned to the heat recovery (not shown).
Process gas may contain in addition to valuable products also unwanted impurities and side products which may accumulate or/and be harmful for heater apparatus(-es) 100, 103 and/or the process units 101 through causing corrosion and poisoning catalytic beds. Purification and separation of streams discharged from heat-consuming processes 101 is performed in the purification unit 105. Unit 105 can comprise a number of appliances, such as filters, cyclones etc., adapted to mechanically remove dust and solid particles. Any conventional purification/separation methods and devices may be utilized. Exemplary purification/separation methods include, but are not limited to: cryogenic separation methods, membrane processes, Pressure Swing Adsorption (PSA), distillation, absorption, and any combination of these methods. The unit 105 may also comprise device configured to increase gas pressure by compression, for example. Typically, purification units 105 operate at lower temperatures than process units 101; therefore, prior to entering the purification unit, a product gas stream is cooled down (in the heat recovery 104, for example). To minimize the extent of deterioration of reactor beds in 101, it is also important to control composition of the recycle gas 11.
Purification unit 105 can be further adapted to purify waste gas(es), e.g. carbon dioxide, for further carbon capture. Waste gases discharged from the steel production facility as stream 7 (
Heated fluidic medium required for carrying out the heat-consuming process(es) 101 is generated by virtue of at least one rotary apparatus 100.
In an embodiment, the heated fluidic medium is generated in the rotary apparatus 100, where an amount of thermal energy is added directly into fluidic medium propagated through said apparatus. In such an event, the heated fluidic medium generated in the rotary apparatus may be for example a process gas, such as a hydrocarbon-containing gas (e.g. methane) (see
The heated fluidic medium generated in the rotary apparatus can be further used as a carrier to transfer thermal energy to the heat-consuming unit 101 configured to implement or mediate a heat-consuming process or processes (101) related to manufacturing of steel. For example, an inert gas such as air, nitrogen or steam (H2O) can be heated in the rotary apparatus 100 and further used to convey the heat generated by the rotary apparatus to the furnace adapted to perform the process 101 related to manufacturing of steel. In this regard, generation of a heated medium (e.g. fluidic or solid streams exploited by the process 101) can be performed outside the rotary apparatus through a process of heat transfer between the heated fluidic medium generated in the rotary apparatus and a suitable medium exploited by the process 101 and thus bypassing the rotary apparatus.
The rotary apparatus 100 configured for generating the heated fluidic medium to be supplied into the steel production facility according to the embodiments comprises a rotor comprising a plurality of rotor blades arranged into at least one row over a circumference of a rotor hub or a rotor disk mounted onto a rotor shaft, and a casing with at least one inlet and at least one exit, the rotor being enclosed within the casing. In the apparatus 100, an amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium passes through the at least one row of rotor blades when propagating inside the casing of the rotary apparatus, between the inlet and the exit, whereby a stream of heated fluidic medium is generated.
Implementation of the rotary apparatus 100 may generally follow the disclosures of a rotary reactor apparatus according to the U.S. Pat. No. 7,232,937 (Bushuev), U.S. Pat. No. 9,494,038 (Bushuev) and U.S. Pat. No. 9,234,140 (Seppala et al), and of a radial reactor apparatus according to the U.S. Pat. No. 10,744,480 (Xu & Rosic), the entire contents of which are incorporated by reference herewith. Any other implementation, which can be configured to adopt the method according to the embodiments, can be utilized.
In the patent documents referenced above, the rotary turbomachine-type apparatuses were designed as reactors for processing hydrocarbons, in particular, for steam cracking. General requirements for these applications are: rapid heating of gases, high temperature, short residence time, and plug flow (a flow model which implies no axial mixing). These requirements have led to designs where the turbomachine type reactors have several heating stages accommodated in a relatively small volume.
The present disclosure is based on an observation that the rotary apparatus (including, but not limited to the ones referenced above) can be electrified and used as a heater to generate the heated fluidic medium further supplied in the heat-consuming process 101, such as a process or processes related to manufacturing of steel. By integration of the rotary apparatus heater unit(s) into the heat-consuming process or processes, significant reductions in greenhouse gas- and particle emissions can be achieved. By way of example, the rotary apparatus can replace fuel-fired heaters in a variety of applications (described hereinbelow). The temperature range can be extended from about 1000° C. (generally achievable with the above referenced reactor devices) to up to at least about 1700° C. and further up to 2500° C. Construction of the rotary apparatuses capable of achieving these high temperatures is possible due to an absence of aerodynamic hurdles.
The rotary apparatus 100 integrated into the steel production facility according to the embodiments and configured to generate the heated fluidic medium for the method(s) according to the embodiment thus comprises the rotor shaft positioned along a horizontal (longitudinal) axis with at least one rotor unit mounted onto the rotor shaft. The rotor unit comprises a plurality of rotor (working) blades arranged over the circumference of a rotor hub or a rotor disk and together forming a rotor blade cascade. The rotary apparatus 100 thus comprises a plurality of rotor (working) blades arranged into at least one row over the circumference of a rotor hub or a rotor disk mounted onto the rotor shaft, and forming an essentially annular rotor blade assembly or rotor blade cascade.
In embodiments, the apparatus further comprises a plurality of stationary vanes arranged into an assembly disposed at least upstream of the at least one row of rotor blades. In this configuration, the rotary apparatus is operated such that the amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium passes through the stationary vanes and the at least one row of rotor blades, respectively, whereby a stream of heated fluidic medium is generated.
In some embodiments, the plurality of stationary vanes can be arranged into a stationary vane cascade (a stator), provided as an essentially annular assembly upstream of the at least one row of rotor blades. The stationary vanes arranged into the assembly disposed upstream of the at least one row of rotor blades may be provided as stationary guide vanes, such as (inlet) guiding vanes (IGV), and be configured, in terms of profiles, dimensions and disposition thereof around the central shaft, to direct the fluid flow into the rotor in a predetermined direction such, as to control and, in some instances, to maximize the rotor-specific work input capability.
The rotary apparatus can be configured with two or more essentially annular rows of rotor blades (rotor blade cascades) sequentially arranged on/along the rotor shaft. In such an event, the stationary guide vanes may be installed upstream of the first row of the rotor blades, upstream of each row of rotor blades in the sequence, or upstream of any selected row of rotor blades in a sequential arrangement of the latter.
In embodiments, the rotary apparatus 100 further comprises a diffuser area arranged downstream of the at least one row of rotor blades (rotor blade cascade). In this configuration, the rotary apparatus is operated such that an amount of thermal energy is imparted to a stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the exit by virtue of a series of energy transformations occurring when said stream of fluidic medium successively passes through the stationary guide vanes, the at least one row of rotor blades and the diffuser area, respectively, whereby a stream of heated fluidic medium is generated. The diffuser area can be configured with or without stationary diffuser vanes. In some configurations, a vaned or vaneless diffuser is arranged, in said diffuser area, downstream of the at least one rotor blade cascade. In some configurations, the diffuser can be implemented as a plurality of stationary (stator) vanes arranged into a diffuser vane cascade, provided as an essentially annular assembly downstream of the rotor.
The rotor, the stationary guide vanes and the diffuser area are enclosed within an internal passageway (a duct) formed in the casing.
In some configurations, such as described for example in U.S. Pat. No. 10,744,480 to Xu and Rosic, provision of a diffuser (device) may be omitted, and the diffuser area may be represented with an essentially vaneless portion of the duct (a so-called vaneless space) located downstream of the rotor and configured, in terms of its geometry and/or dimensional parameters, to diffuse a high-speed fluid flow arriving from the rotor.
Provision of the vaneless portion of the duct is common for all configurations of the rotary apparatus 100 described above. Depending on configuration, the vaneless portion (vaneless space) is arranged downstream of the rotor blades (rf. U.S. Pat. No. 10,744,480 to Xu and Rosic) or downstream of the diffuser vane cascade (rf. U.S. Pat. No. 9,494,038 to Bushuev and U.S. Pat. No. 9,234,140 to Seppala et al). In some configuration described for example by Seppala et al, arrangement of rotating and stationary blade rows in the internal passageway within the casing is such that vaneless portion(s) is/are created between an exit from the stationary diffuser vanes disposed downstream of the rotor blades and an entrance to the stationary guide blades disposed upstream of the rotor blades of a subsequent rotor blade cascade unit.
The terms “upstream” and “downstream” refer hereby to spatial and/or functional arrangement of structural parts or components with relation to a predetermined part- or component, hereby, the rotor, in a direction of fluidic flow stream throughout the apparatus (from inlet to exit).
Overall, the rotor with the working blade cascade can be positioned between the rows of stationary (stator) vanes arranged into essentially annular assemblies (referred to as cascades) at one or both sides of the working blade row. Configurations including two or more rows of rotor blades/rotor blade cascades arranged in series (in sequence) on/along the rotor shaft may be conceived with or without stationary blades in between. In an absence of stationary vanes between the rotor blade rows, the speed of fluidic medium propagating through the duct increases in each subsequent row. In such an event, a plurality of stationary vanes may be arranged into assemblies upstream of a first rotor blade cascade in said sequence (as stationary guide vanes) and downstream of a lastmost rotor blade cascade (as stationary diffuser vanes).
The row of rotor blades (rotor blade cascade) and a portion of the duct downstream of said rotor blades enclosed inside the casing optionally provided with an assembly of stationary diffuser vanes (diffuser area) may be viewed as a minimal process stage (hereafter, the stage), configured to mediate a complete energy conversion cycle. Hence, an amount of kinetic energy added to the stream of fluidic medium by at least one row of rotating blades is sufficient to raise the temperature of the fluidic medium to a predetermined value when said stream of fluidic medium exits the rotor blades and propagates, in the duct, towards a subsequent row of rotor blades, or enters the same row of rotor blades following an essentially helical trajectory formed within the essentially toroidal-shaped casing. The duct (which encloses the periphery of the rotor) is preferably shaped such, that upon propagation of the fluidic stream in the duct, the stream decelerates and dissipates kinetic energy into an internal energy of the fluidic medium, and an amount of thermal energy is added to the stream of fluidic medium.
The stationary guide blade row(s) disposed upstream of the at least one row of rotor blades prepare required flow conditions at the entrance of the rotating blade row (cascade) during the energy conversion cycle.
In some configurations, the process stage is established with the assembly of stationary guide vanes (upstream of the rotor blades), the row of rotor blades and the diffuser area arranged downstream of said rotor blades, the diffuser area provided as the essentially vaneless portion of the duct optionally supplied with diffuser vanes. During the energy conversion cycle, enabled with successive propagation of the stream of fluidic medium through the stationary guide vanes, the at least one row of rotor blades and the diffuser area, respectively, in a controlled manner, mechanical energy of the rotor shaft is converted into kinetic energy and further—into internal energy of the fluid, followed by the rise of fluid temperature. An amount of kinetic energy added to the stream of fluidic medium by rotating blades of the rotor is sufficient to raise the temperature of the fluidic medium to a predetermined value when said stream of fluidic medium exits the rotor blades and passes, inside the duct, through the diffuser area, whereupon the stream decelerates and dissipates kinetic energy into an internal energy of the fluidic medium, and an amount of thermal energy is added to the stream of fluidic medium. In the rotor blade row, the flow accelerates, and mechanical energy of the shaft and rotating blades is transferred to fluidic stream. In at least part of each rotor blade row the flow may reach a supersonic flow condition. In the diffuser area, the high-speed fluid flow arriving from the rotor is diffused with the significant entropy increase, whereby the flow dissipates kinetic energy into the internal energy of the fluidic substance, thus providing thermal energy into the fluid. If the flow upstream of the diffuser is supersonic, the kinetic energy of the fluidic stream is converted into internal energy of the fluid through a system of multiple shocks and viscous mixing and dissipation. An increase in the internal energy of the fluid results in a rise of fluid temperature. The energy conversion function may be performed by the vaneless portion of the duct located downstream of the rotor blades (rf. U.S. Pat. No. 10,744,480 to Xu & Rosic) and/or by an assembly of diffusing vanes, for example (rf. U.S. Pat. No. 9,234,140 to Seppala et al).
The rotary apparatus 100 can be configured as a multistage- or a single-stage solution. Multistage configurations can be conceived comprising a number of rotor units (e.g. 1-5 rows of rotor blades sequentially arranged on/along the rotor shaft) alternating with common diffuser area(s) (vaneless or vaned).
In an exemplary configuration outlined in U.S. Pat. No. 9,234,140 to Seppala et al, the rotary apparatus 100 can be implemented substantially in a shape of a ring torus, where a cross-section of the duct in the meridian plane forms a ring-shaped profile. The apparatus comprises a rotor unit disposed between stationary guide vanes (nozzle vanes), and stationary diffusing vanes. The stages are formed with rows of stationary nozzle vanes, rotor blades and diffusing vanes, through which the fluidic stream propagates, in a successive manner, following a flow path established in accordance with an essentially helical trajectory. In this configuration, fluidic stream circulates through the rotating rotor blade cascade a number of times while propagating inside the apparatus between the inlet and the exit. Similar ring-shaped configuration is described in U.S. Pat. No. 9,494,038 to Bushuev.
In another exemplary configuration outlined in U.S. Pat. No. 9,234,140 to Seppala et al, the rotary apparatus 100 can be configured as an essentially tubular, axial-type turbomachine. In such configuration, the apparatus comprises an extended (elongated) rotor hub, along which a plurality of rotor blades is arranged into a number of sequential rows. The rotor is enclosed within the casing, inner surface of which is provided with the stationary (stator) vanes and diffuser vanes, arranged such that blades/vanes of the stator, rotor- and diffuser cascades alternate along the rotor hub in a longitudinal direction (along the length of the rotor shaft, for inlet to exit). Blades of the rotor cascade at certain position along the rotor in the longitudinal direction form the stage with the adjacent pairs of stationary guide (nozzle) vanes and diffusing vanes, respectively.
In described configurations, the subsequent stages have blade/vane-free space between them.
In still another exemplary configuration outlined in U.S. Pat. No. 10,744,480 to Xu and Rosic, the rotary apparatus 100 can be configured as a radial turbomachine that generally follows a design for centrifugal compressors or centrifugal pumps. The term “centrifugal” implies that fluid flow within the device is radial; therefore, the apparatus may be referred, in the present disclosure, as a “radial-flow apparatus. The apparatus comprises a number of rotor units mounted onto elongated shaft, wherein each rotor unit is preceded with stationary guide vanes. A vaneless portion of the duct shaped in a manner enabling energy conversion (U-bend or S-bend, for example) is located after the rotor unit(s). Additionally, configuration may comprise a separate diffuser device (vaned or vaneless) disposed downstream of the rotor.
In all configurations described above, the rotary apparatus 100 performs, in the method disclosed herein, in similar manner. In operation, the amount of input energy conducted into the at least one rotary apparatus integrated into the heat-consuming process facility is converted into mechanical energy of the rotor. Conditions in the rotary apparatus are adjusted such, as to produce flow rate conditions, at which an amount of kinetic energy added to the stream of fluidic medium by rotating blades of the rotor is sufficient to raise the temperature of the fluidic medium to a predetermined value when said stream of fluidic medium exits the at least one row rotor blades and passes through the duct and/or through the diffuser area to enter the subsequent row of rotor blades or the same row of rotor blades in accordance to the description above. The row(s) of rotor blades may be preceded with stationary guide vanes. Hence, the adjustable condition comprises adjusting at least a flow of fluidic medium propagating inside the casing of the rotary apparatus, between the inlet and the exit. Adjusting the flow may include adjusting such apparatus operation related parameters, as temperature, mass flow rate, pressure, etc. Additionally or alternatively, flow conditions can be adjusted by modifying shape of the duct formed inside the casing.
In some exemplary configurations, the rotary apparatus can be configured to implement a fluidic flow between its inlet(s) and outlet(s) along a flow path established in accordance with any one of: an essentially helical trajectory formed within an essentially toroidal-shaped casing, as discussed in any one of the patent documents U.S. Pat. No. 9,494,038 to Bushuev and U.S. Pat. No. 9,234,140 to Seppala et al; an essentially helical trajectory formed within an essentially tubular casing, as discussed in the patent document U.S. Pat. No. 9,234,140 to Seppala et al; an essentially radial trajectory as discussed in the patent document U.S. Pat. No. 10,744,480 to Xu & Rosic; and along the flow path established by virtue of the stream of fluidic medium in the form of two spirals rolled up into vortex rings of right and left directions, as discussed in the patent document U.S. Pat. No. 7,232,937 to Bushuev). The aerodynamic design of the rotary apparatus can vary.
The rotary apparatus utilizes a drive engine. In preferred embodiments, the apparatus utilizes electrical energy as the input energy and is therefore electric motor-driven. For the purposes of the present disclosure, any appropriate type of electric motor (i.e. a device capable of transferring energy from an electrical source to a mechanical load) can be utilized. Suitable coupling(s) arranged between a motor drive shaft and the rotor shaft, as well as various appliances, such as power converters, controllers and the like, are not described herewith. Additionally, the apparatus can be directly driven by gas- or steam turbine, for example, or any other appropriate drive device. In layouts involving parallel connection of a number of rotary apparatuses 100 to a common heat-consuming unit 101, such as a furnace, for example, one or more of said apparatuses may utilize different type of drive engine, e.g. the electric motor driven apparatuses can be combined with those driven by steam turbine, gas turbine and/or gas engine.
Electric power (defined as the rate of energy transfer per unit time) can be supplied into the rotary apparatus through supplying electric current to the electric motor used to propel a rotary shaft of the apparatus. Supply of electric power into the rotary apparatus can be implemented from an external source or sources (as related to the rotary heater unit/the apparatus 100 and/or the heat-consuming process facility 1000). Additionally or alternatively, electrical energy can be produced internally, within the facility 1000.
An external source or sources include a variety of supporting facilities rendered for sustainable energy production. Thus, electric power can be supplied from an electricity generating system that exploits at least one source of renewable energy or a combination of the electricity generating systems exploiting different sources of renewable energy. External sources of renewable energy can be provided as solar, wind- and/or hydropower. Thus, electric power may be received into the process from at least one of the following units: a photovoltaic electricity generating system, a wind-powered electricity generating system, and a hydroelectric power system. In some exemplary instances, a nuclear power plant may be provided as the external source of electrical power. Nuclear power plants are generally regarded as emission-free. The term “nuclear power plant” should be interpreted as using traditional nuclear power and, additionally or alternatively, fusion power.
Electricity can be supplied from a power plant that utilizes a turbine as a kinetic energy source to drive electricity generators. In some instances, electric power to drive the at least one apparatus 100 can be supplied from at least one gas turbine (GT) provided as a separate installation or within a cogeneration facility and/or a combined cycle power facility, for example. Electric power can thus be supplied from at least one of the following units: a combined cycle power facility, such as a combined cycle gas turbine plant (CCGT), and/or a cogeneration facility configured for electricity production combined with heat recovery and utilization through combined heat and power (CHP), for example. In some examples, the CHP plant can be a biomass fired plant to increase the share of renewable energy in the process described. Additionally or alternatively, supply of electric power can be realized from a spark ignition engine, such as a gas engine, for example, and/or a compression engine, such as a diesel engine, for example, optionally provided as a part of an engine power plant. Still further, any conventional power plant configured to produce electrical energy from fossil raw materials, such as coal, oil, natural gas, gasoline, and the like, typically mediated with the use of steam turbines, can be used to generate electrical energy as an input energy for the rotary apparatus 100. Also hydrogen can be utilized as a source of renewable energy, to be reconverted into electricity, for example, using fuel cells.
Any combination of the abovementioned sources of electric power, realized as external and internal sources, may be conceived. Importing low emission electric power from an alternative (external) source improves energy efficiency of the heat-consuming process facility.
Conducting input energy, comprising electrical power, into a drive engine of the rotary apparatus can be further accompanied with conducting mechanical shaft power thereto from a power turbine, for example, optionally utilizing thermal energy generated elsewhere in the facility 1000 or outside said facility. Shaft power is defined as mechanical power transmitted from one rotating element to another and calculated as a sum of the torque and the speed of rotation of the shaft. Mechanical power is defined, in turn, as an amount of work or energy per unit time (measured in Watt).
In practice, the shaft power from the electric motor and the power turbine, for example, can be divided so that any one of those can provide the full shaft power or a fraction of it.
Temperature boost may be viewed as thermal, chemical or both. In a first configuration (a) also referred to as a “thermal boost”, an additional rotary heater apparatus (designated as 100B on
In a second, additional or alternative, configuration (further referred to as “chemical boost”), the additional heating apparatus designated as 103 (
The reactive chemical-based booster heater unit 103 may be located after the thermal booster heater unit 100, 100B (
Fuel gas can be injected into the booster heater unit 103 through burners along with air (or enriched oxygen) to rise the temperature of gases. If heated gas contains flammable gases and it is possible to consume these gases for heating only air/or oxygen can be added. Process gases can contain H2, NH3, CO, fuel gases (methane, propane, etc.) which may be burned to generate heat. Other reactive gases can be injected to generate heat if feasible.
The additional heater 103 adapted for chemical boost may be configured as a piece of pipe or as a chamber where exothermic reactions take place, and/or it can comprise as at least one rotary apparatus 100 arranged to receive reactive compounds to accommodate exothermic reactions to produce additional heat energy. The booster section 103 can thus comprise at least one rotary apparatus 100. Optionally, the reactive chemicals can be injected directly to the heat consuming process 101 (not shown). Additionally or alternatively, the reactive chemical mediated boost can be implemented in a single apparatus 100, 103, modified accordingly.
In an arrangement involving booster heating, the temperature of the stream of fluidic medium preheated to a predetermined temperature in a first rotary apparatus (100A) can be further raised to a maximum limit in subsequent heater units (100B, 103). By way of example, the temperature of the stream of fluidic medium preheated to about 1700° C. in a primary heater (100A) can be further raised in subsequent heater units (100B, 103) up to 2500° C. and beyond.
Mentioned concepts can be used separately or in combination, so that the reactive chemical 5 can be introduced into any one of the apparatuses 100 connected in parallel or in series (in sequence). Provision of the booster heater(s) is optional.
In additional or alternative configurations, preheating and additional heating can be implemented in the same apparatus 100 (not shown). This can be achieved in multistage configurations, comprising a number of rotor units (e.g. 1-5 rows of rotor blades sequentially arranged on/along the rotor shaft) alternating with common diffuser area(s) (vaneless or vaned).
Additionally or alternatively, booster heating can be used for example in an event, when the temperature of the fluid once heated in the rotary apparatus(es) 100, needs to be raised again after it has transferred its heat to the heat-consuming process 101. Exemplary configuration comprising a number of rotary heater apparatuses 100 (100A, 100B and/or optionally 103) alternating with the heat-consuming units 101 is shown on
Upon connecting the at least two rotary apparatuses, such as 100A, 100B, and optionally 103 (in an event 103 is implemented as a rotary apparatus 100) in parallel or in series, a rotary apparatus assembly can be established (see for example
Rotary apparatuses (100A, 100B, 103, rf.
Additionally or alternatively, at least one rotary apparatus within the assembly can be designed to increase pressure of the fluidic stream. Hence, the at least one rotary apparatus in the assembly can be assigned with a combined heater and blower functionality.
Additionally or alternatively, a stream containing reactive or inert gases (such as stream 8 of
Process streams 6 and 7 of
Another exemplary configuration layout for indirect heating of process fluids with the rotary apparatus 100 is presented on
Although heating of gaseous media can be implemented in the rotary apparatus 100 by simply using the steam as a heating fluid (not shown), in such cases where the pressure of a gaseous process fluid stream is elevated to above 10 bar for example or where the temperature of said gaseous process fluid stream becomes very high, for example up to above 1000° C., it is beneficial to apply the indirect heating concept shown on
In
“Hot” heat-transfer fluid 3 discharged from the rotary apparatus 100 is led into the heat-consuming unit 101 provided, in the layout of
The heat exchanger 101 materials are selected to withstand high temperature hydrogen atmosphere, and/or elevated pressures; however, for stationary equipment like heat exchangers this is still more cost-efficient option than for the rotary apparatus 100.
Using the rotary apparatus 100 allows for optimization of temperature difference in heat exchanger configurations (represented hereby by the heat-consuming units 101), whereby the size of the unit 101 (configured as a heat exchanger, a reactor, a furnace, a heater, etc.) and possible unwanted reactions (fouling, coking) occurring on its surfaces due too high surface temperature can be minimized. High surface temperatures may cause excess fouling in process heaters. Indirect heating can be used for example to replace process heaters in various applications related to production of steel.
Any one of the rotary apparatuses 100A, 100B can be equipped with a fluid recycle arrangement (see stream 4,
In some configurations, the rotary apparatus 100 can utilize flue gases with low oxygen content exhausted from a conventional fired heater. In such an event, hot flue gases exhausted from the fired heater are mixed with recycle gases (stream 4,
The following description pertains to
Coke is generated from coal 306 in a coking process 308. During coking, coal 306 is heated in the absence of oxygen to 1000-1250° C. for about 18 hours to remove volatile impurities like heavy aromatic hydrocarbons, sulphur and ammonia. These volatiles are vented to what is known as coke plant off-gas (COG) 310 that is also rich in CO, CO2 and hydrogen. The high temperatures necessary for coking is typically achieved by burning fossil fuels 312.
Iron ore sinter 302 is made in a sintering plant 317 from iron ore 314 in a sintering process (317). In a typical sintering process, crushed iron ore 314 is transported with a conveyor belt. Fine coke powder 316 is mixed with the iron ore 314 to provide fuel for heating. The mixture of iron ore 314 and coke 316 is set on fire using burners configured to burn natural gas 318, and the off gases 320 from burning this mixture are evacuated from below the conveyor belt, thus providing even heat distribution throughout the material layer on the belt. The solid product, clean iron ore sinter 302, is crushed, cooled and sized after sintering to make feedstock for the blast furnace 300.
In the blast furnace 300, coke 304 and iron ore sinter 302 are fed into the furnace together with limestone, and hot air or oxygen (1000-1200° C.) 322 (the latter is typically fed into the furnace from the bottom). The hot air 322 reacts with the coke 304 and pulverised coal and forms a reduction gas that abstracts the oxygen from the iron ore 302. At the same time, heat is created which is required when melting the reduced iron ore. Limestone is added to help with removal of sand silicates in form of ‘slag’. The products from the blast furnace include molten product (molten metal iron) 324, slag 325 and blast furnace gas (BFG) 326 that is rich in CO and hydrogen.
After the blast furnace 300, the molten metal product 324 is mixed with pure oxygen 327 in a basic oxygen furnace 328, which removes carbon and other chemical impurities through the oxygen converter process, forming a steel product 330, typically in the form of steel sheets. The majority of carbon is removed as CO, making basic oxygen furnace gas (BOFG) 332 rich in CO and therefore rich in calorific value and carbon content. As the steel sheets 330 are cooled, they are typically sent to a post-processing unit 334, such as a hot strip mill for hot rolling the sheets 330 into coils 336 before shipping to customers. In hot rolling, the steel sheets 330 are heated to 1000-1270° C. by burning natural gas 338 on top of the sheets 330, producing a CO2-rich off gas 340. Any impurities (‘slag’) is removed from the surface of the sheets 330 and sheets are milled to desired thickness, cooled down and rolled into coils 336 for shipment.
The main off-gases from steel making are coke plant off-gas (COG) 310, blast furnace gas (BFG) 326 and basic oxygen furnace gas (BOFG) 332. All of these gases are rich in nitrogen and CO2, but they also contain components with heating value (hydrogen, CO and hydrocarbons) and are thus typically incinerated in a power plant 342 for energy, producing a CO2-rich off gas 344. Recently, material valorisation of these off-gases has been extensively studied. The most promising pathways for material valorisation of these streams include reverse-water gas shift reaction and dry reforming, which both can be used together with a reducing chemical (hydrogen or methane) to convert CO2 and hydrocarbons in the gas streams into synthesis gas-like mixture of CO and hydrogen. The synthesis gas (syngas) can be converted into base chemicals in numerous ways, most industrially relevant being methanol production and Fischer-Tropsch synthesis.
As used herein, “valorisation” refers to the economic analysis of waste material for reuse and recycling. Thus, as used herein, “valorisation” is synonymous with “recycling”.
The following non-limiting examples illustrate the use of the rotary apparatus 100 in steel making.
Instead of heating the coal in a coke plant with fossil fuel fired heaters, the rotary apparatus 100 can be used to provide heat for the coking of coal. Heating can be done by circulating a gas 346 (air, nitrogen, steam) through the rotary apparatus 100 where it heats up to about 1300-1500° C. The heated gas 348 is then transferred to the coke oven 308 where the heated gas 348 releases part of its heat to coal 306. The coking process typically operates at around 1200° C. for about 18 hours. Exhaust gas 350 from the coke oven, which has cooled to a temperature low relative to the oven 308, but still on the order of around 500° C., can be recycled back to the rotary apparatus for optimal heat integration, as well as heat and energy recycling. Depending on the amount of exhaust gas 350 recycled from the oven 308 to the rotary apparatus 100, the amount of gas 346 necessary to maintain optimal flow and energy capacity may be reduced accordingly. Through recycling of exhaust gases 350, an amount of the off-gases 310 vented to the atmosphere can be minimized.
The coking process and related plant 308 correspond to the heat-consuming unit 101 described herein above.
Instead of heating the crude iron ore in a sintering plant with fossil fuel fired heaters and coke, the rotary apparatus 100 can be used to provide heating for reducing iron oxide ore into iron ore sinter. Heating can be done by circulating a gas 352 (air, nitrogen, steam) through the rotary apparatus 100 where it heats up to temperature above about 1200° C. The heated gas 354 is then passed to the conveyor belt 356 where the reduction of iron oxide ore 314 into iron ore sinter 302 takes place. The conveyor belt can be perforated. Exhaust gas 358 from the conveyor belt 356 can be partly recycled back to the rotary apparatus 100 for optimal heat integration. Part of the recycled gas is purged as purge gas 360 (and replaced with fresh gas/a make-up gas 352 in a similar amount) using a gas splitter or scrubber 362 due to accumulation of impurities in the recycle. Alternatively, impurities from sintering process can be removed from the recycled gas to keep their concentration at acceptable level.
In some configurations, section 317 represents a pellet plant. The processes of sintering and pelletisation both perform essentially same function, that is, prepare iron ore material for being processes in a blast furnace. Iron ore sinter and pellets are both agglomerated forms of iron ore suitable for use as blast furnace burden materials.
The sintering/pelletising process and related sinter/pellet plant 317 correspond to the heat-consuming unit 101 described herein above.
In the reduction of iron oxide into iron, the blast furnace 300 needs air or oxygen for converting coal into CO that acts as the reducing gas for converting iron ore into iron. Externally pre-heating this air or oxygen up to about 1200° C. is commonly practised to reduce the consumption of coke and the subsequent generation of CO2 in the blast furnace 300. First, pre-heating of the air/oxygen or the ‘hot blast’ is done through capturing a part of the heat from blast furnace off-gas 364 and achieving the final temperature of about 1200° C. via heating provided from fossil fuels incineration. The rotary apparatus 100 can be used to provide the final heating step instead of fossil fuels (otherwise burned in the furnace 300). Additionally, the rotary apparatus 100 can be used to recycle a part of the blast furnace off-gases 364 back to blast furnace 300 for valorisation of the unreacted CO in the off-gas.
In this embodiment, blast furnace 300 accepts a feedstock 366 that includes iron ore sinter 302, coke 304 (rf.
3CO(g)+Fe2O3(s)□2Fe(l)+3CO2(g)
At around 800-850° C., carbon dioxide both in the supplied air 368 and as a result of Reaction 1 reacts with coke in the feedstock 366 in a reaction having the following formula:
CO2(g)+C(s)□2CO(g)
At around 850° C., limestone decomposes and forms slag (CaSiO3) in a series of reactions having the following formulas:
CaCO3(s)□CaO(s)+CO2(g)
CaO(s)+SiO2(s)□CaSiO3(l)
At around 1000° C., hot air reacts with coke in a reaction having the following formula:
C(s)+O2(g)□CO2(g)
In blast furnace 300, the molten iron 324 has the greatest density and is extracted from the bottom of the furnace. The molten slag 325 sits on top of the molten iron 324 and is extracted from a position above the molten iron 324.
Exhaust gas 364 exits the blast furnace 300 and is combined with fresh air 370 in a heat exchanger 372 in an amount necessary to supplant the air consumed in the blast furnace 300. Some of the exhaust gas 364 and fresh air 370 is transferred to rotary apparatus 100, while some is transferred to a gas splitter/scrubber 362 for capturing excess CO2. The blast furnace gas (BFG) 326 is discharged from scrubber 362 and the remaining gas is recombined in rotary apparatus 100.
After the blast furnace 100, the molten metal product (molten iron 324) is mixed with pure oxygen in the basic oxygen furnace 328 (rf.
The post-processing unit 334 can be configured for post-processing of a steel product via any one of: heat treatment, carburizing, casting and/or rolling. In the carburizing process, the steel product is upgraded with a source of carbon, such as carbon monoxide, for example, to make it harder. The unit 334 may include a casting unit, such as a continuous caster, for example, where steel sheets 330 are produced, and a rolling mill, such as a (continuous) hot strip mill for example, to where the cooled down steel sheets 330 can be sent for being rolled into coils 336 before shipping to customers. In some instances, at least the caster can be integrated with the oxygen converter 328 (rf.
The blast furnace 300 corresponds to the heat-consuming unit 101 described herein above.
The post-processing unit 334 corresponds to the heat-consuming unit 101 described herein above.
Coke plant, basic oxygen furnace and blast furnace off-gases are rich in calorific value and carbon. Hence, these streams can be valorised either materially or energetically. Energetic valorisation is a standard way of valorising the gases by incinerating them into energy in a power plant or equivalent. This, however, leads to CO2 emissions and recent innovation activity has focused on material valorisation of these streams. Material valorisation of streams containing hydrogen and C1 chemicals is typically done by converting hydrocarbons and CO2 in the off-gases into synthesis gas. Synthesis gas is a mixture of CO and hydrogen with varying proportions and is a raw material for some common base chemical reactions like methanol synthesis of Fischer-Tropsch synthesis. An even simpler way to valorise these gases is to manipulate their constituents (sometimes together with an external methane source) towards maximal CO and H2 content. CO and H2 can both act as reducing agents in the blast furnace and can therefore be recycled back to the blast furnace after removal of impurities.
Table 1 gives a typical composition of three main off-gas steams from steel making (source: Angewandte Chemie; Volume 60, Issue 21; May 17, 2021, Pages 11852-11857).
Adjusting the gas composition towards optimal CO/H2 ratio required by selected application can be done using four generally known high temperature catalytic reactions:
CO+H2OCO2+H2
CO2+H2CO+H2O
CH4=H2OCO+3H2
CO2+CH42H2+2CO
As avoidance of CO2 emissions is typically the target of such C1 chemistry manipulation, Reaction 5 (Water Gas Shift reaction, WGS) is not recommended as it produces CO2. Instead, sustainable hydrogen from electrolysis or methane pyrolysis should be used to increase share of hydrogen in syngas mixtures.
Temperatures required by reverse water gas shift reaction, methane steam reforming or methane ‘dry’ reforming are typically between 800° C. and 1200° C., and such high temperatures are today achieved by incineration of fossil fuels. The rotary apparatus 100 is an electrified and emission-free technology to heat the off-gases to temperatures required by those catalytic reactions.
Each of the blast furnace 300, coking process 308, sintering plant/pellet plant 317, and basic oxygen furnace 328 produce off-gases which carry residual heat. In the embodiment depicted in
The heated off-gases and make-up hydrogen/methane, 404, are then transported to a catalytic reactor 406 configured for the endothermic, high temperature reactions described in Reactions 5-8. Catalytic reactor 406 may be a series of reactors depending on the needs of the application. The series of reactors may be implemented as shown on
With reference to
A novel way to mitigate CO2 emission from steel industry is to use hydrogen instead of coal as a reducing agent. Unlike coke reduction, hydrogen reduction is an endothermic reaction and requires additional heat input to heat hydrogen to reaction temperature and to maintain the reaction temperature. This additional heat input typically comes from excess hydrogen that is oxidised in the furnace, leading to significant increase in hydrogen consumption.
Application of the rotary apparatus 100 in iron ore reduction with hydrogen would supply this additional heat by heating the hydrogen to, or above, reduction temperature of about 900° C., while also recycling gaseous reaction products, mainly water and unreacted hydrogen, partially back to the reduction process for optimal heat recovery.
The DRI process unit 504 corresponds to the heat-consuming unit 101 described herein above.
Example 7 supplements the previous Example 6. The rotary apparatus 100 can be used to produce a heated fluidic medium in the processes of direct reduction of iron ore to direct reduced iron carried out in a heat-consuming unit 101 configured as a process unit for reducing iron ore to metal iron without melting it. As mentioned above, the DRI process can be carried out in a furnace, in a kiln, or in a reactor, typically of a fluidized bed type using hydrogen gas or coke gas as reducing agents, where solids are contacted with hot reducing gas. Various types of kilns, such as rotary kilns or grate kilns, can be utilized.
An exemplary rotary kiln is a rotating horizontal vessel where rotation around the axis of the vessel provides mixing for the solids inside the kiln. Specially designed internals can be added to improve mixing of the solids and hot gas. A grate kiln is a type of kiln where the incoming solid raw material is first ‘grated’ to grind and size it to optimise its surface area for contacting with hot gas. In steel making, grate kilns can be used for pelletising low quality iron sources (lump ore, beach sand, ilmenite and iron ore fines) that will not convert to iron ore sinter in sintering plant. These pellets can be fed to the blast furnace as co-feed with iron ore sinter (see iron ore sinter/pellets 502 supplied into the DRI process unit 504,
Rotary kilns can be used for direct reduction of iron ore into iron by mixing the ore pellets with coke and contacting the solid mixture with hot air. Coke reacts with oxygen in the hot air to yield CO, which acts as a reducing agent for iron ore, converting it to iron and CO2. Although the reaction scheme and the reactants are the same as in blast furnace (rf.
Grate and rotary kilns are often used in combination—pellets produced in the grate kiln can be fed into the rotary kiln for direct reduction, or the rotary kiln can be part of a grate kiln system for improving the heat transfer between solids and hot gas.
The application of the rotary apparatus in rotary and grate kilns is straightforward and generally follows a route outlined in description to
Alternatively, in some applications the gas heated in the rotary apparatus 100 can be hydrogen, in which case the use of coke (and associated CO2 emissions) is not necessary as hot hydrogen can act as a reducing agent for iron ore. Unreacted hydrogen and water produced in hydrogen reduction reaction can be separated after the kiln and hydrogen recycled back to the kiln through the rotary apparatus, further improving the recycling of both energy and materials. Direct reduction of iron ore with hydrogen is described with regard to
It is clear to a person skilled in the art that with the advancement of technology the basic ideas of the present invention may be implemented and combined in various ways. The invention and its embodiments are thus not limited to the examples described herein above, instead they may generally vary within the scope of the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63255433 | Oct 2021 | US |
