Cold water, wide range wet venturi scrubber for a direct reduction plant

Abstract

A top gas scrubber for use in a direct reduced iron process includes a top gas inlet, a venturi gas outlet sector, a first top gas fuel sector, a second top gas fuel sector, and a venturi. The top gas inlet receives a top gas from a shaft furnace, and a venturi outlet of the venturi gas outlet sector removes a hot venturi gas formed from the top gas. A first outlet of the first top gas fuel sector removes a first top gas fuel formed from the top gas. A second outlet of the second top gas fuel sector removes a second top gas fuel formed from the top gas. The first and second top gas fuels are lower in temperature than the hot venturi gas. The venturi is fluidly coupled between the top gas inlet and each of the venturi outlet, the first outlet, and the second outlet.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present disclosure claims the benefit of priority of co-pending U.S. Provisional Patent Application No. 63 / 780,731, filed on Mar. 31, 2025, and entitled “COLD WATER, WIDE RANGE WET VENTURI SCRUBBER FOR A DIRECT REDUCTION PLANT,” the contents of which are incorporated in full by reference herein.TECHNICAL FIELD

[0002] The present disclosure relates generally to the direct reduced iron (DRI) production and steelmaking fields. More specifically, the present disclosure relates to a cold water, wide range wet venturi scrubber for a direct reduction (DR) plant, associated DRI system, or DRI process.BACKGROUND

[0003] Within a typical natural gas (NG) DR plant, there is a large recirculating water load. This load necessitates the use of large clarifiers and large cooling tower systems. Further, the temperature in the clarifier is critical to the operation of the DR plant near-stoichiometric reformer. Reforming can only be initiated on a start-up, whether it is a cold start or a re-start from a DR plant production delay, after the clarifier water temperature has reached a sufficient temperature to maintain the desired humidity in the process gas coming from the top gas scrubber (TGS). It is this minimum humidity level that protects the near-stoichiometric reformer from carbon deposition on start-up. Oftentimes, on a re-start of the DR plant, operators must wait many hours for the water system to heat up before they can initiate reforming and return to normal operation. During this time the plant is basically producing no product. The colder the climate the worse the delays.

[0004] Standard practice sets the start-up limit for a safe start for reforming at 8 mol % H2O in the feed gas to the reformer, the preferred value is closer to 13 mol %. The lower the starting point, the shorter the wait to re-start, but the greater the carbon deposition risk to the reformer. A more significant occurrence of this problem is manifested in very cold climates such as Canada, Russia, Sweden, Northern Europe, etc., where the ambient temperature in the wintertime results in cold water temperatures in a cooling tower falling to 15° C. or below. To achieve the 8 mol % water content in a near-stoichiometric reformer equipped DR plant with the current design, the clarifier water temperature needs to be raised to 55-60° C. In some environments, no matter how long the DR plant waits to heat up the water system, it is quite simply impossible to achieve, therefore DR plants are forced to initiate reforming with lower than the recommended water content in the feed gas, thereby subjecting the reformer into a riskier start-up sequence that if mishandled could lead to potentially catastrophic catalyst damage via Boudouard carbon deposition.

[0005] As such, a need exists in the art for a top gas scrubber and associated DRI system and process that overcome the above limitations.

[0006] This background is provided as an illustrative contextual environment only. It will be readily apparent to those of ordinary skill in the art that the systems and methods of the present disclosure may be implemented in other contextual environments as well.SUMMARY

[0007] Therefore, it is an object of the present disclosure to provide a top gas scrubber for use in a DRI process and associated DRI system that overcome the limitations of the known art. Embodiments of the present disclosure improve upon prior systems and methods to produce DRI in a SF utilizing natural gas (NG) potentially supplemented with hydrogen (H2) and mitigate the risks of Boudouard carbon deposition in an associated DRI reformer.

[0008] Embodiments of the present disclosure change the entire control philosophy and flow pattern of current wet scrubbing technology from a water-based control technology to a gas-based control technology and design. The incorporation of a bypass section within the scrubber design changes the basic control concept from one of trying to maintain gas temperature and humidification by inhibiting gas cooling using hot water to a design philosophy of controlling temperature and humidity simply by hot and cold gas mixing in the proper controlled proportion. In previous designs, the control relied on having hot enough packing spray water to hold the heat in the gas and trim the outlet gas to the desired temperature and humidity. The issue with such prior methods is that it requires that either the entire water system be heated up to the needed temperature for gas conditioning control or, at the very least, a large portion of the water would have to be selectively heated. This heating requires many hours and sometimes days and, in the most extreme of weather conditions, is not even possible. These prior methods also possess a built-in time lag, as the entire packed portion of the scrubber must equilibrate under new water conditions for the control system to assess the need to apply more hot or cold water to achieve the target exit gas conditions.

[0009] Various embodiments of the present disclosure remove the reliance on the water temperature to heat the system up to or beyond a desired outlet control temperature and humidity. For instance, embodiments of the concept disclosed herein may rely exclusively on the heat carried into the top gas scrubber with the entering gas to provide all the energy needed to reach the target temperature and humidity. Such functionality allows the top gas scrubber outlet temperature and humidity to be almost instantly changed by simply controlling the temperature control valve (TCV) that regulates the mixing ratio of a hot venturi exit gas to a cold process gas, thereby adjusting the desired mixed process gas temperature and humidity in the time it takes to stroke the valve change.

[0010] Embodiments of the disclosed top gas scrubber include three internal chambers that provide all the flexibility to address the process control and operating needs of the near-stoichiometric reformer within one vessel. Such a three-chamber design simplifies water draining and pressure sealing of the system and provides for more precise optimization of the design of the packing surface area and the mist removal efficiency.

[0011] Embodiments of the present disclosure significantly improve upon conventional solutions that rely on slow moving controls, heat transfer from a large heat source that is hard to get enough energy into, provide less flow flexibility (operable in a much smaller range), and utilize 30% more water, which further introduces issues related to recycling and pumping such excess water. Embodiments of the disclosed top gas scrubber (TGS) design of the present disclosure eliminate the need for a hot water well, hot water pumps, and any hot water piping, as non-limiting examples. For example, a recirculating water system load in a typical plant may be reduced by more than 700 m3 / h. Particularly and for some embodiments, the venturis and packing sprays disclosed here may be run on cold water only. The elimination of the need for heated water also eliminates inefficiencies and time wasted waiting for prior art water system to heat up. By implementation of the disclosed subject matter, reforming may be initiated as soon as a furnace burden is hot enough to support reduction, which holds true for re-starts and cold start-ups.

[0012] To achieve the foregoing and other objects and advantages, in one aspect, the present subject matter is directed to a top gas scrubber for use in a direct reduced iron process. The top gas scrubber includes a top gas inlet configured to receive a top gas from a shaft furnace. The top gas scrubber also includes a venturi gas outlet sector having a venturi outlet configured to remove a hot venturi gas formed from the top gas. The top gas scrubber further includes a first top gas fuel sector having a first outlet configured to remove a first top gas fuel formed from the top gas and having a lower temperature than the hot venturi gas. The top gas scrubber additionally includes a second top gas fuel sector having a second outlet configured to remove a second top gas fuel formed from the top gas and having a lower temperature than the hot venturi gas. Furthermore, the top gas scrubber includes a venturi fluidly coupled between the top gas inlet and each of the venturi outlet, the first outlet, and the second outlet.

[0013] In at least one embodiment, the top gas scrubber may further include a combined top gas fuel conduit fluidly coupled to the first outlet of the first top gas fuel sector and selectively fluidly coupled to the second outlet of the second top gas fuel sector. In some such embodiments, the combined top gas fuel conduit may be configured to provide a burner fuel for combustion in the direct reduced iron process. In some such embodiments, the burner fuel may include the first top gas fuel, the second top gas fuel, or both. Additionally or alternatively, the top gas scrubber may further include a second top gas fuel conduit coupled between the second outlet of the second top gas fuel sector and the combined top gas fuel conduit. In some such embodiments or different embodiments, the top gas scrubber may further include a second top gas fuel valve configured to selectively fluidly couple the combined top gas fuel conduit and the second outlet.

[0014] Furthermore or in alternative embodiments, the top gas scrubber may further include a process gas conduit coupled to the venturi outlet of the venturi gas outlet sector and configured to selectively provide a process gas for use in the direct reduced iron process. In some such embodiments or different embodiments, the top gas scrubber may further include a temperature control valve coupled between the process gas conduit and the combined top gas fuel conduit. In some such embodiments, the temperature control valve may be configured to selectively fluidly couple the process gas conduit and the combined top gas fuel conduit and alter an amount of the burner fuel bypassed to the process gas conduit to cool the process gas. Furthermore or alternatively, the top gas scrubber may further include a ranging valve fluidly coupled between the venturi outlet of the venturi gas outlet sector and the temperature control valve and configured to alter an amount of the hot venturi gas provided to the process gas conduit.

[0015] In additional or alternative embodiments, the first top gas fuel sector may further include packing surrounding the first outlet and cooling nozzles configured to spray a cooling water on the packing. Furthermore or alternatively, the second top gas fuel sector may further include packing surrounding the second outlet and cooling nozzles configured to spray a cooling water on the packing. Additionally or alternatively, the top gas scrubber may further include one or more baffle walls configured to separate two of the venturi gas outlet sector, the first top gas fuel sector, and the second top gas fuel sector. Additionally or alternatively, the top gas scrubber may further include three baffle walls within the interior of the top gas scrubber. Additionally or alternatively, each baffle wall may be configured to separate two of the venturi gas outlet sector, the first top gas fuel sector, and the second top gas fuel sector.

[0016] In additional or alternative embodiments, the top gas scrubber may further include one or more top gas inlet water injection nozzles configured to swirl unheated water within the top gas received from the shaft furnace at the top gas inlet of the top gas scrubber. Additionally or alternatively, the top gas scrubber may further include one or more venturi throat water injection nozzles configured to inject unheated water within a throat of the venturi. In some such embodiments or different embodiments, the first top gas fuel sector may further include a mist eliminator circumscribing the first outlet and configured to reduce a water content of the first top gas fuel. Additionally or alternatively, the second top gas fuel sector may further include a mist eliminator circumscribing the second outlet and configured to reduce a water content of the second top gas fuel. Additionally or alternatively, the venturi gas outlet sector may further include a mist eliminator circumscribing the venturi outlet and configured to reduce a water content of the hot venturi gas.

[0017] In an additional or alternative aspect, the present subject matter is directed to a method of treating a top gas of a direct reduced iron process utilizing a top gas scrubber. The method includes receiving the top gas from a shaft furnace utilizing a top gas inlet of the top gas scrubber. The method also includes flowing the top gas through a venturi of the top gas scrubber. The method additionally includes forming a venturi gas and a top gas fuel from the top gas flown through the venturi. The method further includes removing the venturi gas from the top gas scrubber utilizing a venturi outlet of a venturi gas outlet sector of the top gas scrubber. In another element, the method includes removing the top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber. Furthermore, the method includes tempering a temperature of the venturi gas downstream of the venturi outlet utilizing tempering gas comprising a portion of the top gas fuel and thereby form a process gas for use in the direct reduced iron process.

[0018] In at least one embodiment, the method may further include reducing a temperature of the top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector. Additionally or alternatively, the method may also include controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas. In additional or alternative embodiments, the method may additionally include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising only natural gas or comprising at least 60% natural gas and between 1% and 40% hydrogen gas.

[0019] In additional or alternative configurations, forming the top gas fuel from the top gas may include forming a first top gas fuel and a second top gas fuel. In some such embodiments, the top gas fuel removed utilizing the first outlet of the first top gas fuel sector may include the first top gas fuel. Furthermore or alternatively, the method may also include removing the second top gas fuel from the top gas scrubber utilizing a second outlet of a second top gas fuel sector of the top gas scrubber. Additionally or alternatively, the method may further include reducing a temperature of the second top gas fuel by spraying cooling water on packing surrounding the second outlet of the second top gas fuel sector.

[0020] In additional or alternative embodiments, the method may also include swirling unheated water within the top gas received from the shaft furnace utilizing one or more top gas inlet water injection nozzles. Furthermore or alternatively, the method may additionally include injecting unheated water within a throat of the venturi utilizing one or more venturi throat water injection nozzles. Additionally or alternatively, the method may also include reducing a water content of the first top gas fuel utilizing a mist eliminator circumscribing the first outlet. In additional or alternative configurations, the method further include reducing a water content of the second top gas fuel utilizing a mist eliminator circumscribing the second outlet. Additionally or alternatively, the method may also include reducing a water content of the venturi gas utilizing a mist eliminator circumscribing the venturi gas outlet.

[0021] In additional or alternative embodiments, the method may further include selectively combining the first top gas fuel and the second top gas fuel downstream of the top gas scrubber via control of a valve associated with a conduit coupled between the second outlet of a second top gas fuel sector and another conduit fluidly coupled to the first outlet of a first top gas fuel sector. In some such embodiments or different embodiments, the tempering gas may include a combination of the first top gas fuel and the second top gas fuel. Additionally or alternatively, the method may further include controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas. Additionally or alternatively, the method may also include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising greater than 40% hydrogen gas.

[0022] Embodiments of the invention can include one or more or any combination of the above features and configurations.

[0023] Additional features, aspects, and advantages of the invention will be set forth in the detailed description of illustrative embodiments that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein. It is to be understood that both the foregoing general description and the following detailed description present various embodiments of the invention and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the accompanying drawings, in which:

[0025] FIG. 1 is a process diagram illustrating one exemplary embodiment of a DRI process utilizing a natural gas reformer and suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter;

[0026] FIG. 2 is a process diagram illustrating one exemplary embodiment of a DRI process utilizing a NG reformer with makeup H2 and suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter;

[0027] FIG. 3 is a schematic diagram illustrating one exemplary embodiment of a TGS and associated TGS system with a suitable valving arrangement, in accordance with aspects of the present subject matter;

[0028] FIG. 4 is a top plan view schematically illustrating an exemplary embodiment of a TGS showing a piping arrangement thereof, in accordance with aspects of the present subject matter;

[0029] FIG. 5 is a top plan view schematically illustrating an exemplary embodiment of a TGS showing a piping arrangement thereof in combination with a TGS system with a suitable valving arrangement, in accordance with aspects of the present subject matter;

[0030] FIG. 6A illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter;

[0031] FIG. 6B illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter;

[0032] FIG. 6C illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter;

[0033] FIG. 6D illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter; and

[0034] FIG. 6E illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter.

[0035] It will be readily apparent to those of ordinary skill in the art that aspects of illustrated embodiments may be used in any desired combinations, without limitation. Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.DETAILED DESCRIPTION

[0036] The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the representative embodiments set forth herein. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. It is envisioned that other embodiments may perform similar functions and / or achieve similar results. Any and all such equivalent embodiments and examples are within the scope of the present invention and are intended to be covered by the appended claims.

[0037] The exemplary embodiments are provided so that this disclosure will be both thorough and complete and will fully convey the scope of the invention and enable one of ordinary skill in the art to make, use, and practice the invention. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0038] The terms “coupled,”“fixed,”“attached to,”“communicatively coupled to,”“operatively coupled to,” and the like refer to both direct coupling, fixing, attaching, communicatively coupling, and operatively coupling as well as indirect coupling, fixing, attaching, communicatively coupling, and operatively coupling through one or more intermediate components or features, unless otherwise specified herein. “Communicatively coupled to” and “operatively coupled to” can refer to physically and / or electrically related components.

[0039] The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.

[0040] As used herein, the terms “first,”“second,”“third,” and the like may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

[0041] Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and / or systems. For example, the approximating language may refer to being within a 1, 2, 4, 10, 15, or 20 percent margin.

[0042] Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0043] Again, embodiments of the present disclosure change the entire control philosophy and flow pattern of current wet scrubbing technology from a water-based control technology to a gas-based control technology and design. The incorporation of a bypass section within the scrubber design changes the basic control concept from one of trying to maintain gas temperature and humidification by inhibiting gas cooling using hot water to a design philosophy of controlling temperature and humidity simply by hot and cold gas mixing in the proper controlled proportion. In previous designs, the control relied on having hot enough packing spray water to hold the heat in the gas and trim the outlet gas to the desired temperature and humidity. The issue with such prior methods is that it requires that either the entire water system be heated up to the needed temperature for gas conditioning control or, at the very least, a large portion of the water would have to be selectively heated. This heating requires many hours and sometimes days and, in the most extreme of weather conditions, is not even possible. These prior methods also possess a built-in time lag, as the entire packed portion of the scrubber must equilibrate under new water conditions for the control system to assess the need to apply more hot or cold water to achieve the target exit gas conditions.

[0044] Various embodiments of the present disclosure remove the reliance on the water temperature to heat the system up to or beyond a desired outlet control temperature and humidity. For instance, embodiments of the concept disclosed herein may rely exclusively on the heat carried into the top gas scrubber with the entering gas to provide all the energy needed to reach the target temperature and humidity. Such functionality allows the top gas scrubber outlet temperature and humidity to be almost instantly changed by simply controlling the temperature control valve (TCV) that regulates the mixing ratio of a hot venturi exit gas to a cold process gas, thereby adjusting the desired mixed process gas temperature and humidity in the time it takes to stroke the valve change.

[0045] Embodiments of the disclosed top gas scrubber include three internal chambers that provide all the flexibility to address the process control and operating needs of the near-stoichiometric reformer within one vessel. Such a three-chamber design simplifies water draining and pressure sealing of the system and provides for more precise optimization of the design of the packing surface area and the mist removal efficiency.

[0046] Embodiments of the present disclosure significantly improve upon conventional solutions that rely on slow moving controls, heat transfer from a large heat source that is hard to get enough energy into, provide less flow flexibility (operable in a much smaller range), and utilize 30% more water, which further introduces issues related to recycling and pumping such excess water. Embodiments of the disclosed top gas scrubber (TGS) design of the present disclosure eliminate the need for a hot water well, hot water pumps, and any hot water piping, as non-limiting examples. For example, a recirculating water system load in a typical plant may be reduced by more than 700 m3 / h. Particularly and for some embodiments, the venturis and packing sprays disclosed here may be run on cold water only. The elimination of the need for heated water also eliminates inefficiencies and time wasted waiting for prior art water system to heat up. By implementation of the disclosed subject matter, reforming may be initiated as soon as a furnace burden is hot enough to support reduction, which holds true for re-starts and cold start-ups.

[0047] Referring now generally to the drawings, FIG. 1 illustrates an exemplary embodiment of a DRI process utilizing a natural gas reformer and suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter. It will be appreciated that the exemplary direct reduced iron processes and systems depicted and described herein are by way of example only, and, in other exemplary embodiments, the DRI process, system, shaft furnace, plant, or the like may have any other suitable configuration. One or more of the method elements disclosed herein may be utilized in a suitable process for the direct reduction of iron and incorporated in any suitably configured direct reduction process, system, shaft furnace, or the like. It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently.

[0048] As shown in the exemplary direct reduction system and associated process / method (system / method 100) with a natural gas (NG) reformer 12 illustrated in FIG. 1, the SF 1 may generally receive an iron oxide 2 at the top and discharges the product DRI 3 from the bottom. The top gas 4 from the SF 1, which is the spent gas after the reduction of the iron oxide, generally contains the reaction product, such as H2O and CO2, as well as the unused reductant, such as H2, CO, and CH4. After the top gas 4 is cooled and cleaned with a scrubber 5, most of cleaned process gas 7 is recycled to the SF 1 through the reduction gas loop since it still contains H2 and CO. What is called the top gas fuel 6, which is the excess gas caused by the volume expansion via NG reforming, is removed from the reduction gas loop and combusted as reformer burner fuel with the addition of makeup burner fuel gas 20, as required. Makeup NG 16 is added to the cleaned process gas 7 downstream of a compressor 8, and a mixed gas stream 9 may be preheated with a preheater 10. A preheated feed gas 11 may be fed to the reformer tubes containing a catalyst in the reformer 12, which enhances the reforming reaction of the methane derived from the NG to produce H2 and CO for the reductant of the iron oxide. Enrichment NG 18 and oxygen 19 may optionally be added to the reformed gas 13 to increase CH4 content and temperature, before feeding a resulting bustle gas 14 to the SF 1. Carburizing hydrocarbon gas 17 may be injected in a transition zone of the SF 1, which is located below the bustle gas 14 injection level, to carburize the DRI product 3 of the SF 1. In various embodiments disclosed herein, the transition zone may be defined as the portion of the SF 1 below injection of the bustle gas 14 and at or above injection of the carburizing hydrocarbon gas 17. All bustle gas 14 injected through the main bustle ports located in the lower section of the SF 1 or below the reduction zone flows upward through the iron oxide bed.

[0049] FIG. 2 illustrates an exemplary embodiment of a DRI process utilizing a natural gas reformer and makeup H2 suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter. It will be appreciated that the exemplary direct reduced iron processes and systems depicted and described herein are by way of example only, and, in other exemplary embodiments, the DRI process, system, shaft furnace, plant, or the like may have any other suitable configuration. One or more of the method elements disclosed herein may be utilized in a suitable process for the direct reduction of iron and incorporated in any suitably configured direct reduction process, system, shaft furnace, or the like. It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently.

[0050] As shown in the exemplary direct reduction system and associated process / method (system / method 200) illustrated in FIG. 2, the system / method 200 may generally be configured similar to the embodiment of system / method 100 described above with respect to FIG. 1. However, a substantial difference with respect to FIG. 1 is to add makeup H2 50 to the reduction gas loop as makeup H2 to process gas 92 and / or optional makeup H2 gas 91 to reformed gas 13, so that makeup H2 50 will flexibly replace a part of NG makeup 16 or H2 / CO reformed from NG with reformer 12 (e.g., reformed gas 13) to reduce CO2 emission from the direct reduction plant, depending on H2 availability. Or, the direct reduction plant with a NG reformer 12 can startup only with NG 16, but later the available amount of makeup H2 16 can be flexibly added to replace makeup NG 16 when H2 becomes available.

[0051] Referring now to FIGS. 3-4, FIG. 3 schematically illustrates an exemplary embodiment of a TGS system illustrating a valving arrangement suitable for use with embodiments of the TGS, in accordance with aspects of the present subject matter; and FIG. 4 schematically illustrates a top plan view of an exemplary embodiment of a TGS showing a piping arrangement thereof, in accordance with aspects of the present subject matter.

[0052] The embodiment of the TGS system illustrated in FIG. 3 and TGS of FIG. 4 may be utilized with the exemplary embodiment of the DRI system / method 100 illustrated in FIG. 1, a similar DRI system / method with a NG reformer, the DRI system / method 200 illustrated in FIG. 2, or a similar DRI system / method utilizing a NG reformer and makeup H2, as non-limiting examples. It should be appreciated that the disclosed TGS system may be utilized in conjunction with any suitable DRI process, system, shaft furnace, plant, or the like. One or more of the method elements disclosed herein may be utilized in a suitable process for the direct reduction of iron and incorporated in any suitably configured direct reduction process, system, shaft furnace, or the like. It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently.

[0053] As shown, the TGS 5 may include a top gas inlet 322 for receiving a top gas 4 from a SF 1. Furthermore, the TGS 5 generally includes a venturi 424 (reference number omitted from FIG. 3 for clarity) fluidly coupled between the top gas inlet 322 and each of a venturi gas sector 426 (or a venturi outlet 428 thereof), a first top gas fuel sector 430 (or a first outlet 432 thereof), and a second top gas fuel sector 434 (or a second outlet 436 thereof). Furthermore and as shown particularly in FIG. 4, the TGS 5 may include multiple internal flow dividers, baffle walls, or the like (baffle walls 437) separating such sectors 426, 430, 434 and / or the flowpaths thereof. For example, three baffle walls 437 may be arranged within the interior of the TGS 5, and each baffle wall 437 may separate two of the venturi gas sector 426, the first top gas fuel sector 430, and the second top gas fuel sector 434.

[0054] In the exemplary TGS system 300 illustrated in FIG. 3 and / or TGS 5 of FIG. 4, the need for a hot water generation / supply within the DR plant and / or system may be entirely eliminated. However and as shown particularly in FIG. 3, the TGS system 300 and TGS 5 may include one or more top gas inlet water injection nozzles (omitted from FIG. 4 for simplicity) for swirling unheated water and / or H2O (swirl water 338) within the top gas 4 received from the SF 1 at the top gas inlet 324 of the top gas scrubber 5. Additionally or alternatively, the TGS system 300 and TGS 5 may include one or more venturi throat water injection nozzle (omitted from FIG. 4 for simplicity) configured to inject unheated water and / or H2O (throat water 340) within a throat of the venturi 424.

[0055] As shown, the venturi sector 426 generally includes the venturi outlet 428 for removal of a hot venturi gas (venturi gas 342) formed from the top gas 4 received from the SF 1. It should be appreciated that the venturi sector 426 and / or the venturi outlet 428 may be appropriately sized and / or configured for the flow of the venturi gas 342. It should be appreciated that, in several embodiments, the venturi sector 426 may not include packing and cooling nozzles included in the other sectors 430, 434, as described herein. However and as shown in FIG. 4, the venturi outlet sector 422 may include a mist eliminator 444 circumscribing the venturi outlet 428 and configured to reduce a water content of the hot venturi gas 342. In some embodiments, the mist eliminator 444 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 444 may additionally or alternatively include any other configuration suitable to reduce the water content of the hot venturi gas 342. It should also be appreciated that the mist eliminator 444 may be appropriately sized for the flow of the hot venturi gas 342. Generally, the venturi gas 342 may be directed through the mist eliminator 444 without being contacted by any water other than the swirl water 338 and throat water 340.

[0056] Referring still generally to FIGS. 3-4, the first top gas fuel sector 430 generally includes the first outlet 432 for removal of a first top gas fuel 346 formed from the top gas 4 received from the SF 1. It should be appreciated that the first top gas fuel sector 430 and / or the first outlet 432 may be appropriately sized and / or configured for the flow of the first top gas fuel 346. The first top gas fuel 346 generally has a lower temperature than the hot venturi gas 342 removed from the TGS 5 utilizing the venturi sector 426 and / or the venturi outlet 428. For example and in some embodiments, the first top gas fuel sector 430 may include packing 448 surrounding the first outlet 432 and cooling nozzles (omitted from FIGS. 3-4) for spraying a cooling water and / or H2O on the packing 448 surrounding the first outlet 432. In some embodiments and as shown particularly in FIG. 4, the first top gas fuel sector 430 may include a mist eliminator 450 circumscribing the first outlet 432 and configured to reduce a water content of the first top gas fuel 346. In some embodiments, the mist eliminator 450 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 450 may additionally or alternatively include any other configuration suitable to reduce the water content of the first top gas fuel 346. It should also be appreciated that the area and / or volume of the packing 448 and the mist eliminator 450 may be appropriately sized for the flow of the first top gas fuel 346.

[0057] As further illustrated, the second top gas fuel sector 434 generally includes the second outlet 436 for removal of a second top gas fuel 352 formed from the top gas 4 received from the SF 1. It should be appreciated that the second top gas fuel sector 434 and / or the second outlet 436 may be appropriately sized and / or configured for the flow of the second top gas fuel 352. The second top gas fuel 352 generally has a lower temperature than the hot venturi gas 342 removed from the TGS 5 utilizing the venturi sector 426 and / or the venturi outlet 428. For example and in some embodiments, the second top gas fuel sector 434 may include packing 454 surrounding the second outlet 436 and cooling nozzles (omitted from FIGS. 3-4) for spraying a cooling water and / or H2O on the packing 454 surrounding the second outlet 436. In some embodiments and as shown particularly in FIG. 4, the second top gas fuel sector 434 may include a mist eliminator 456 circumscribing the second outlet 436 and configured to reduce a water content of the second top gas fuel 352. In some embodiments, the mist eliminator 456 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 456 may additionally or alternatively include any other configuration suitable to reduce the water content of the second top gas fuel 352. It should also be appreciated that the area and / or volume of the packing 454 and the mist eliminator 456 may be appropriately sized for the flow of the second top gas fuel sector 434.

[0058] Referring now to FIG. 5, FIG. 5 schematically illustrates a top plan view of an exemplary embodiment of a TGS showing a piping arrangement thereof in combination with a TGS system illustrating a valving arrangement suitable for use with embodiments of the TGS, in accordance with aspects of the present subject matter. It should be appreciated that the TGS illustrated in FIG. 5 may be configured the same or similar to the TGS 5 illustrated and described with respect to FIG. 4, e.g., including venturi gas sector, a first top gas fuel sector, and a second top gas fuel sector. However, various of the reference numbers of FIG. 4 associated with the components thereof are omitted from FIG. 5 for clarity.

[0059] Referring now predominantly to FIGS. 3 and 5, the TGS system 300 may include a process gas conduit or an assembly of process gas conduit sections (process gas conduit 558 of FIG. 5) coupled to the venturi outlet 428 of the venturi gas outlet sector 426 and configured to selectively provide the hot venturi gas 342 for use as the process gas 7 in a DRI process, after optional supplementation as described herein. As shown, the TGS system 300 may include a ranging valve 360 (e.g., as an inline valve and / or coupled between sections of a multi-section process gas conduit 558). The ranging valve 360 generally fluidly couples the venturi outlet 428 of the venturi gas outlet sector 426 to a temperature control valve (368 as described in more detail below), the flow of the process gas 7, and / or to a compressor 8. Additionally or alternatively, ranging valve 360 may allow for controlled altering of the amount of the hot venturi gas 342 flown through the downstream portions of the process gas conduit 558.

[0060] The TGS system 300 may may also include a combined top gas fuel conduit or an assembly of combined top gas fuel conduit sections (combined top gas fuel conduit 562 of FIG. 5) fluidly coupled to the first outlet 432 of the first top gas fuel sector 430. The combined top gas fuel conduit 562 is generally configured to provide the first top gas fuel 346, after optional supplementation with the second top gas fuel 352, as top gas fuel 6 to be utilized a burner fuel for combustion in the associated DRI process. Thus, it should be appreciated that the top gas fuel 6 and / or burner fuel may include the first top gas fuel 346 and / or the second top gas fuel 352. In some embodiments, the combined top gas fuel conduit 562 may be selectively fluidly coupled to the second outlet 436 of the second top gas fuel sector 434. For example, TGS system 300 may may further include a second top gas fuel conduit or an assembly of second top gas fuel conduit sections (second top gas fuel conduit 564) coupled between the second outlet 436 of the second top gas fuel sector 434 and the combined top gas fuel conduit 562. A second top gas fuel valve 366 may be controllable to selectively fluidly couple the combined top gas fuel conduit 562 and the second outlet 436 of the second top gas fuel sector 434.

[0061] Referring still predominantly to FIGS. 3 and 5, the TGS system 300 may may also include a temperature control valve 368 coupled between the process gas conduit 558 and the combined top gas fuel conduit 562. The temperature control valve 368 may be controllable to selectively fluidly couple the process gas conduit 558 and the combined top gas fuel conduit 562. Additionally or alternatively, the temperature control valve 368 may be controllable to alter an amount of the top gas fuel 6, the first top gas fuel 346, the second top gas fuel 352, and / or burner fuel bypassed to the process gas conduit 558 to cool the hot venturi gas 346 and / or resulting process gas 7.

[0062] As also shown, the top gas fuel 6 and / or burner fuel or at least a portion 6a thereof may be subsequently provided to the top gas fuel line for subsequent combustion in the DRI process, e.g., as burner fuel for a suitable reformer. A suitable valve, pressure control valve, or the like (PCV valve 370) may selectively provide the top gas fuel 6 and / or the portion 6a thereof to the top gas fuel line and / or alter an amount of such top gas fuel 6, 6a provided to the top gas fuel line. Optionally and as shown, a suitable valve, pressure control valve, or the like (PCV valve 372) may optionally provide another portion 6b of the top gas fuel 6 to a flare system for combustion as needed for emergency or operational safety release. Additionally or alternatively, the process gas line for communicating process gas 7 may include a mist eliminator 374 (FIG. 3) configured to reduce a water content of the process gas 7. In some embodiments, the mist eliminator 374 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 374 may additionally or alternatively include any other configuration suitable to reduce the water content of the process gas 7. It should also be appreciated that the mist eliminator 374 may be appropriately sized for the flow of the process gas 7.

[0063] Generally, the hot venturi gas 342 may be much higher in temperature than any required process gas 7 temperature. Thus, the hot venturi gas 342 may be tempered with the top gas fuel 6, the first top gas fuel 346, and / or the second top gas fuel 352 to achieve the same or similar temperature and humidity in the process gas 7 that would have previously been achieved by employing packing and hot water. Even if one assumes the use of top gas (TG) waste heat recovery on the venturi top gas inlet 322 reducing the venturi inlet gas to 200° C. (normally 350-400° C.) and the throat water 340 coming into the venturi at 15° C., the hot venturi gas 342 may still exit the TGS 5 at a gas temperature of approximately 65-75° C. (16-18 mol % H2O). Even in a worst-case scenario, there is sufficient heat in the top gas 4 to keep the hot venturi gas 342 above a temperature required for the process gas 7 under all known reformer operating conditions. Embodiments of the present application temper the hot venturi gas 342 with the cooler and / or conditioned top gas fuel 6 to arrive at target conditions for process gas 7 (e.g., temperature and / or humidity) allowing for safe reformer operation (e.g., NG reformer 12 of FIGS. 1-2).

[0064] It should be appreciated that all of the top gas fuel 6, the first top gas fuel 346, and / or the second top gas fuel 352 may be cooled by flowing through the respective packing 448, 454 sprayed with only cold water, as described generally above with respect to FIG. 4. Thus, there is no required hot water supply for utilization in the packing spray water system embodiments of the present disclosure. Therefore, conditions of process gas 7 suitable for use with the reformer may be met as soon as the furnace bed of the SF 1 is hot enough to support reduction. Such embodiments may completely eliminate time often lost waiting on the water system to reach temperature in prior art top gas scrubbers and / or associated DRI systems. Furthermore, the TGS 5 and / or TGS system 300 may support a transition to the use of hydrogen (H2) into the inlet of the reformer 12 (e.g., a near-stoichiometric reformer).

[0065] Embodiments of the TGS 5 and / or TGS system 300 disclosed herein may be incorporated in a DRI process / system utilizing 100% NG (e.g., the system / method 100 described above with respect to FIG. 1 or similar) and / or in a DRI process / system utilizing at least 60% natural gas and between 1% and 40% hydrogen gas (e.g., the system / method 200 described above with respect to FIG. 2 or similar). In such embodiments, first top gas fuel 346 may pass through the first top gas fuel sector 430 sized to carry all of the top gas fuel 6, including the portion thereof diverted for cooling of the hot venturi gas 342 and / or process gas 7 to arrive at target conditions of the process gas 7. As generally described above, the packing 448 and mist eliminator 450 of the first top gas fuel sector 430 may be appropriately sized for the flow of the first top gas fuel 346 and top gas fuel 6. Similarly, mist eliminator 444 of the venturi gas sector 426 is generally appropriately sized for the flow of the hot venturi gas 342. In such use cases, the second top gas fuel valve 366 may be completely closed to fluidly isolate the combined top gas fuel conduit 562 from the second outlet 436 of the second top gas fuel sector 434.

[0066] Embodiments of the TGS 5 and / or TGS system 300 disclosed herein may alternatively be incorporated in a DRI process / system utilizing natural gas and greater than 40% hydrogen makeup gas (e.g., the system / method 200 described above with respect to FIG. 2 or similar). In such embodiments, the first top gas fuel 346 may pass through the first top gas fuel sector 430 sized to carry only a portion of the top gas fuel 6. The second top gas fuel sector 434 may be sized to carry the remainder of the top gas fuel 6 (i.e., the second top gas fuel 352). In such use cases, the second top gas fuel valve 366 may be opened to fluidly couple the combined top gas fuel conduit 562 to the second outlet 436 of the second top gas fuel sector 434 and / or to controlled to alter an amount of the second top gas fuel 352 provided to the combined top gas fuel conduit 562. Generally, the first top gas fuel sector 430 and the second top gas fuel sector 434 may be sized to together carry all of the top gas fuel 6, including the portion thereof diverted for cooling of the hot venturi gas 342 and / or process gas 7 to arrive at target conditions of the process gas 7. As generally described above, the packing 448 and mist eliminator 450 of the first top gas fuel sector 430 is generally appropriately sized for the flow of the first top gas fuel 346, and the packing 454 and mist eliminator 456 of the second top gas fuel sector 434 is generally appropriately sized for the flow of the second top gas fuel 352. Similarly, mist eliminator 444 of the venturi gas sector 426 is generally appropriately sized for the flow of the hot venturi gas 342.

[0067] Referring now to the incorporation of the TGS 5 and / or TGS system 300 in any suitable DRI process / system utilizing natural gas and potentially hydrogen make-up gas, the target gas conditions of the process gas 7 may generally be achieved via control of the temperature control valve (TCV) 368. In exemplary embodiments, TCV 368 may be controlled to alter an amount of the top gas fuel 6 bypassed from the combined top gas fuel conduit 562 into the hot venturi gas 342 of the process gas conduit 558 to achieve the target temperature and / or humidity of the process gas 7. It should be appreciated that, in several embodiments, because the top gas fuel 6 and the hot venturi gas 342 are fully saturated, such gases 6, 342 may mix well. For example, mixing components may not be required at the junction of such gases 6, 342. In a particular use case, should the TCV 368 be controlled to a fully open position prior to reaching the target temperature of the process gas 7, the ranging valve 360 of the process gas conduit 558 may be closed slightly to add more relative flow capability to the TCV 368 thereby extending a range of control of the TCV 368, as the need arises.

[0068] While omitted from the FIGS. here, it should be appreciated that a control unit, control system, controller, or the like (control unit) may provide operation control of any of the valves disclosed herein, thereby allowing for adjustment of the flow rate of the hot venturi gas 342, the second top gas fuel 352, the portion of the top gas fuel 6 bypassed to the process gas conduit 558, the top gas fuel 6 and / or burner fuel or at least a portion 6a thereof supplied to the burners of the reformer 12, and / or the another portion 6b of the top gas fuel 6 supplied to the associated flare system. In various embodiments, such control may be based, at least in part, on the temperature and / or humidity of the top gas 4 and / or process gas 7. Such control unit may generally include an electronic control unit, multiple associated control units, and / or a combination of one or more processing devices and at least one memory or memory device, as is well known in the art, communicatively coupled to any of the components described herein. Any of the process or method elements described herein may be implemented by the control unit utilizing one or more appropriate algorithms. In various embodiments, the control unit may include or be configured as one or more of a distributed control system, a temperature indication and control (TIC) system, an analysis indication and control (AIC) system, combinations thereof, or the like.

[0069] Referring now to FIGS. 6A-6E, FIGS. 6A-6E illustrate exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter. Any of such method 600 elements may, optionally, be computer-implemented, such as via a suitable control unit. Furthermore, the method 600 and / or elements thereof may be utilized to control or in association with any of the embodiments of the DRI system 100, the DRI system 200, SF 1, TGS 5, TGS system 300, components thereof described herein, or any other suitably configured DRI SF, system, process, plant, TGS, TGS system, or the like.

[0070] Referring now predominantly to FIG. 6A, the method 600 may include receiving the top gas from a shaft furnace utilizing a top gas inlet of the top gas scrubber (method element 602). The method 600 may further include swirling unheated water within the top gas received from the shaft furnace utilizing at least one top gas inlet water injection nozzle (method element 604). The method 600 may additionally include flowing the top gas through a venturi of the top gas scrubber (method element 606). Some embodiments of the method 600 may include injecting unheated water within a throat of the venturi utilizing at least one venturi throat water injection nozzle (method element 608). Some embodiments of the method 600 include forming a venturi gas and a top gas fuel from the top gas flown through the venturi (method element 610). Additionally or alternatively, the method 600 may include forming a venturi gas, a first top gas fuel, and a second top gas fuel from the top gas flown through the venturi (method element 612). The method 600 may also include removing the venturi gas from the top gas scrubber utilizing a venturi outlet of a venturi gas outlet sector of the top gas scrubber (method element 614).

[0071] Referring now predominantly to FIG. 6B, the method 600 may include reducing a water content of the venturi gas utilizing a mist eliminator circumscribing the venturi gas outlet (method element 616). Additionally or alternatively, the method 600 may also include removing the top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber (method element 618). In some embodiments of the method 600 may include reducing a temperature of the top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector (method element 620). The method 600 may further include reducing a water content of the top gas fuel utilizing a mist eliminator circumscribing the first outlet (method element 622). Additionally or alternatively, the method 600 may include removing the first top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber (method element 624).

[0072] Referring now predominantly to FIG. 6C, in additional or alternative embodiments, the method 600 may include reducing a temperature of the first top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector (method element 626). In additional or alternative embodiments, the method 600 may include reducing a water content of the first top gas fuel utilizing a mist eliminator circumscribing the first outlet (method element 628). Some embodiments of the method 600 may include removing the second top gas fuel from the top gas scrubber utilizing a second outlet of a second top gas fuel sector of the top gas scrubber (method element 630). The method 600 may further include reducing a temperature of the second top gas fuel by spraying cooling water on packing surrounding the second outlet of the second top gas fuel sector (method element 632). Additionally or alternatively, the method 600 may include reducing a water content of the second top gas fuel utilizing a mist eliminator circumscribing the second outlet (method element 634).

[0073] Referring now predominantly to FIG. 6D, the method 600 may include selectively combining the first top gas fuel and the second top gas fuel downstream of the top gas scrubber via control of a valve associated with a conduit coupled between the second outlet of a second top gas fuel sector and another conduit fluidly coupled to the first outlet of a first top gas fuel sector (method element 636). The method 600 may also include tempering a temperature of the venturi gas downstream of the venturi outlet utilizing tempering gas comprising a portion of the top gas fuel and thereby form a process gas for use in the direct reduced iron process (method element 638). Some embodiments of the method 600 may include controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas (method element 640).

[0074] Referring now predominantly to FIG. 6E, the method 600 may further include supplying, via a PCV, a portion of the top gas fuel to a flare system for combustion as needed for emergency or operational safety release and control, via the PCV, an amount of the portion of the top gas fuel supplied to the flare system (method element 642). Additionally or alternatively, the method 600 may include altering, via a pressure control valve (PCV) an amount of top gas fuel or a portion thereof provided to the top gas fuel line as burner fuel for a reformer (method element 644). The method 600 may also include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising only natural gas or comprising at least 60% natural gas and between 1% and 40% hydrogen gas (method element 646). In some such embodiments, the top gas fuel may only include the first top gas fuel. In alternative embodiments, the method 600 may include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising greater than 40% hydrogen gas (method element 648). In some such embodiments, the top gas fuel may include both the first top gas fuel and the second top gas fuel. Embodiments of the method 600 may also include utilizing the process gas downstream of the top gas scrubber as a reducing gas in a direct reduction shaft furnace (method element 650). It should be appreciated that the process gas may be further processed (e.g., in a preheater, a reformer, a natural gas reformer, etc.) and / or may be further supplemented before being injected and counterflown within the direct reduction shaft furnace.

[0075] It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially.

[0076] Again, embodiments of the present disclosure change the entire control philosophy and flow pattern of current wet scrubbing technology from a water-based control technology to a gas-based control technology and design. The incorporation of a bypass section within the scrubber design changes the basic control concept from one of trying to maintain gas temperature and humidification by inhibiting gas cooling using hot water to a design philosophy of controlling temperature and humidity simply by hot and cold gas mixing in the proper controlled proportion. In previous designs, the control relied on having hot enough packing spray water to hold the heat in the gas and trim the outlet gas to the desired temperature and humidity. The issue with such prior methods is that it requires that either the entire water system be heated up to the needed temperature for gas conditioning control or, at the very least, a large portion of the water would have to be selectively heated. This heating requires many hours and sometimes days and, in the most extreme of weather conditions, is not even possible. These prior methods also possess a built-in time lag, as the entire packed portion of the scrubber must equilibrate under new water conditions for the control system to assess the need to apply more hot or cold water to achieve the target exit gas conditions.

[0077] Various embodiments of the present disclosure remove the reliance on the water temperature to heat the system up to or beyond a desired outlet control temperature and humidity. For instance, embodiments of the concept disclosed herein may rely exclusively on the heat carried into the top gas scrubber with the entering gas to provide all the energy needed to reach the target temperature and humidity. Such functionality allows the top gas scrubber outlet temperature and humidity to be almost instantly changed by simply controlling the temperature control valve (TCV) that regulates the mixing ratio of a hot venturi exit gas to a cold process gas, thereby adjusting the desired mixed process gas temperature and humidity in the time it takes to stroke the valve change.

[0078] Embodiments of the disclosed top gas scrubber include three internal chambers that provide all the flexibility to address the process control and operating needs of the near-stoichiometric reformer within one vessel. Such a three-chamber design simplifies water draining and pressure sealing of the system and provides for more precise optimization of the design of the packing surface area and the mist removal efficiency.

[0079] Embodiments of the present disclosure significantly improve upon conventional solutions that rely on slow moving controls, heat transfer from a large heat source that is hard to get enough energy into, provide less flow flexibility (operable in a much smaller range), and utilize 30% more water, which further introduces issues related to recycling and pumping such excess water. Embodiments of the disclosed top gas scrubber (TGS) design of the present disclosure eliminate the need for a hot water well, hot water pumps, and any hot water piping, as non-limiting examples. For example, a recirculating water system load in a typical plant may be reduced by more than 700 m3 / h. Particularly and for some embodiments, the venturis and packing sprays disclosed here may be run on cold water only. The elimination of the need for heated water also eliminates inefficiencies and time wasted waiting for prior art water system to heat up. By implementation of the disclosed subject matter, reforming may be initiated as soon as a furnace burden is hot enough to support reduction, which holds true for re-starts and cold start-ups.

[0080] Although the present disclosure is illustrated and described with reference to embodiments and examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and / or achieve like results. All such equivalent embodiments and examples are within the scope of the present disclosure, are contemplated thereby, and are intended to be covered by the following, non-limiting Claims for all purposes.

Examples

Embodiment Construction

[0036]The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the representative embodiments set forth herein. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. It is envisioned that other embodiments may perform similar functions and / or achieve similar results. Any and all such equivalent embodiments and examples are within the scope of the present invention and are intended to be covered by ...

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present disclosure claims the benefit of priority of co-pending U.S. Provisional Patent Application No. 63 / 780,731, filed on Mar. 31, 2025, and entitled “COLD WATER, WIDE RANGE WET VENTURI SCRUBBER FOR A DIRECT REDUCTION PLANT,” the contents of which are incorporated in full by reference herein.TECHNICAL FIELD

[0002] The present disclosure relates generally to the direct reduced iron (DRI) production and steelmaking fields. More specifically, the present disclosure relates to a cold water, wide range wet venturi scrubber for a direct reduction (DR) plant, associated DRI system, or DRI process.BACKGROUND

[0003] Within a typical natural gas (NG) DR plant, there is a large recirculating water load. This load necessitates the use of large clarifiers and large cooling tower systems. Further, the temperature in the clarifier is critical to the operation of the DR plant near-stoichiometric reformer. Reforming can only be initiated on a start-up, whether it is a cold start or a re-start from a DR plant production delay, after the clarifier water temperature has reached a sufficient temperature to maintain the desired humidity in the process gas coming from the top gas scrubber (TGS). It is this minimum humidity level that protects the near-stoichiometric reformer from carbon deposition on start-up. Oftentimes, on a re-start of the DR plant, operators must wait many hours for the water system to heat up before they can initiate reforming and return to normal operation. During this time the plant is basically producing no product. The colder the climate the worse the delays.

[0004] Standard practice sets the start-up limit for a safe start for reforming at 8 mol % H2O in the feed gas to the reformer, the preferred value is closer to 13 mol %. The lower the starting point, the shorter the wait to re-start, but the greater the carbon deposition risk to the reformer. A more significant occurrence of this problem is manifested in very cold climates such as Canada, Russia, Sweden, Northern Europe, etc., where the ambient temperature in the wintertime results in cold water temperatures in a cooling tower falling to 15° C. or below. To achieve the 8 mol % water content in a near-stoichiometric reformer equipped DR plant with the current design, the clarifier water temperature needs to be raised to 55-60° C. In some environments, no matter how long the DR plant waits to heat up the water system, it is quite simply impossible to achieve, therefore DR plants are forced to initiate reforming with lower than the recommended water content in the feed gas, thereby subjecting the reformer into a riskier start-up sequence that if mishandled could lead to potentially catastrophic catalyst damage via Boudouard carbon deposition.

[0005] As such, a need exists in the art for a top gas scrubber and associated DRI system and process that overcome the above limitations.

[0006] This background is provided as an illustrative contextual environment only. It will be readily apparent to those of ordinary skill in the art that the systems and methods of the present disclosure may be implemented in other contextual environments as well.SUMMARY

[0007] Therefore, it is an object of the present disclosure to provide a top gas scrubber for use in a DRI process and associated DRI system that overcome the limitations of the known art. Embodiments of the present disclosure improve upon prior systems and methods to produce DRI in a SF utilizing natural gas (NG) potentially supplemented with hydrogen (H2) and mitigate the risks of Boudouard carbon deposition in an associated DRI reformer.

[0008] Embodiments of the present disclosure change the entire control philosophy and flow pattern of current wet scrubbing technology from a water-based control technology to a gas-based control technology and design. The incorporation of a bypass section within the scrubber design changes the basic control concept from one of trying to maintain gas temperature and humidification by inhibiting gas cooling using hot water to a design philosophy of controlling temperature and humidity simply by hot and cold gas mixing in the proper controlled proportion. In previous designs, the control relied on having hot enough packing spray water to hold the heat in the gas and trim the outlet gas to the desired temperature and humidity. The issue with such prior methods is that it requires that either the entire water system be heated up to the needed temperature for gas conditioning control or, at the very least, a large portion of the water would have to be selectively heated. This heating requires many hours and sometimes days and, in the most extreme of weather conditions, is not even possible. These prior methods also possess a built-in time lag, as the entire packed portion of the scrubber must equilibrate under new water conditions for the control system to assess the need to apply more hot or cold water to achieve the target exit gas conditions.

[0009] Various embodiments of the present disclosure remove the reliance on the water temperature to heat the system up to or beyond a desired outlet control temperature and humidity. For instance, embodiments of the concept disclosed herein may rely exclusively on the heat carried into the top gas scrubber with the entering gas to provide all the energy needed to reach the target temperature and humidity. Such functionality allows the top gas scrubber outlet temperature and humidity to be almost instantly changed by simply controlling the temperature control valve (TCV) that regulates the mixing ratio of a hot venturi exit gas to a cold process gas, thereby adjusting the desired mixed process gas temperature and humidity in the time it takes to stroke the valve change.

[0010] Embodiments of the disclosed top gas scrubber include three internal chambers that provide all the flexibility to address the process control and operating needs of the near-stoichiometric reformer within one vessel. Such a three-chamber design simplifies water draining and pressure sealing of the system and provides for more precise optimization of the design of the packing surface area and the mist removal efficiency.

[0011] Embodiments of the present disclosure significantly improve upon conventional solutions that rely on slow moving controls, heat transfer from a large heat source that is hard to get enough energy into, provide less flow flexibility (operable in a much smaller range), and utilize 30% more water, which further introduces issues related to recycling and pumping such excess water. Embodiments of the disclosed top gas scrubber (TGS) design of the present disclosure eliminate the need for a hot water well, hot water pumps, and any hot water piping, as non-limiting examples. For example, a recirculating water system load in a typical plant may be reduced by more than 700 m3 / h. Particularly and for some embodiments, the venturis and packing sprays disclosed here may be run on cold water only. The elimination of the need for heated water also eliminates inefficiencies and time wasted waiting for prior art water system to heat up. By implementation of the disclosed subject matter, reforming may be initiated as soon as a furnace burden is hot enough to support reduction, which holds true for re-starts and cold start-ups.

[0012] To achieve the foregoing and other objects and advantages, in one aspect, the present subject matter is directed to a top gas scrubber for use in a direct reduced iron process. The top gas scrubber includes a top gas inlet configured to receive a top gas from a shaft furnace. The top gas scrubber also includes a venturi gas outlet sector having a venturi outlet configured to remove a hot venturi gas formed from the top gas. The top gas scrubber further includes a first top gas fuel sector having a first outlet configured to remove a first top gas fuel formed from the top gas and having a lower temperature than the hot venturi gas. The top gas scrubber additionally includes a second top gas fuel sector having a second outlet configured to remove a second top gas fuel formed from the top gas and having a lower temperature than the hot venturi gas. Furthermore, the top gas scrubber includes a venturi fluidly coupled between the top gas inlet and each of the venturi outlet, the first outlet, and the second outlet.

[0013] In at least one embodiment, the top gas scrubber may further include a combined top gas fuel conduit fluidly coupled to the first outlet of the first top gas fuel sector and selectively fluidly coupled to the second outlet of the second top gas fuel sector. In some such embodiments, the combined top gas fuel conduit may be configured to provide a burner fuel for combustion in the direct reduced iron process. In some such embodiments, the burner fuel may include the first top gas fuel, the second top gas fuel, or both. Additionally or alternatively, the top gas scrubber may further include a second top gas fuel conduit coupled between the second outlet of the second top gas fuel sector and the combined top gas fuel conduit. In some such embodiments or different embodiments, the top gas scrubber may further include a second top gas fuel valve configured to selectively fluidly couple the combined top gas fuel conduit and the second outlet.

[0014] Furthermore or in alternative embodiments, the top gas scrubber may further include a process gas conduit coupled to the venturi outlet of the venturi gas outlet sector and configured to selectively provide a process gas for use in the direct reduced iron process. In some such embodiments or different embodiments, the top gas scrubber may further include a temperature control valve coupled between the process gas conduit and the combined top gas fuel conduit. In some such embodiments, the temperature control valve may be configured to selectively fluidly couple the process gas conduit and the combined top gas fuel conduit and alter an amount of the burner fuel bypassed to the process gas conduit to cool the process gas. Furthermore or alternatively, the top gas scrubber may further include a ranging valve fluidly coupled between the venturi outlet of the venturi gas outlet sector and the temperature control valve and configured to alter an amount of the hot venturi gas provided to the process gas conduit.

[0015] In additional or alternative embodiments, the first top gas fuel sector may further include packing surrounding the first outlet and cooling nozzles configured to spray a cooling water on the packing. Furthermore or alternatively, the second top gas fuel sector may further include packing surrounding the second outlet and cooling nozzles configured to spray a cooling water on the packing. Additionally or alternatively, the top gas scrubber may further include one or more baffle walls configured to separate two of the venturi gas outlet sector, the first top gas fuel sector, and the second top gas fuel sector. Additionally or alternatively, the top gas scrubber may further include three baffle walls within the interior of the top gas scrubber. Additionally or alternatively, each baffle wall may be configured to separate two of the venturi gas outlet sector, the first top gas fuel sector, and the second top gas fuel sector.

[0016] In additional or alternative embodiments, the top gas scrubber may further include one or more top gas inlet water injection nozzles configured to swirl unheated water within the top gas received from the shaft furnace at the top gas inlet of the top gas scrubber. Additionally or alternatively, the top gas scrubber may further include one or more venturi throat water injection nozzles configured to inject unheated water within a throat of the venturi. In some such embodiments or different embodiments, the first top gas fuel sector may further include a mist eliminator circumscribing the first outlet and configured to reduce a water content of the first top gas fuel. Additionally or alternatively, the second top gas fuel sector may further include a mist eliminator circumscribing the second outlet and configured to reduce a water content of the second top gas fuel. Additionally or alternatively, the venturi gas outlet sector may further include a mist eliminator circumscribing the venturi outlet and configured to reduce a water content of the hot venturi gas.

[0017] In an additional or alternative aspect, the present subject matter is directed to a method of treating a top gas of a direct reduced iron process utilizing a top gas scrubber. The method includes receiving the top gas from a shaft furnace utilizing a top gas inlet of the top gas scrubber. The method also includes flowing the top gas through a venturi of the top gas scrubber. The method additionally includes forming a venturi gas and a top gas fuel from the top gas flown through the venturi. The method further includes removing the venturi gas from the top gas scrubber utilizing a venturi outlet of a venturi gas outlet sector of the top gas scrubber. In another element, the method includes removing the top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber. Furthermore, the method includes tempering a temperature of the venturi gas downstream of the venturi outlet utilizing tempering gas comprising a portion of the top gas fuel and thereby form a process gas for use in the direct reduced iron process.

[0018] In at least one embodiment, the method may further include reducing a temperature of the top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector. Additionally or alternatively, the method may also include controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas. In additional or alternative embodiments, the method may additionally include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising only natural gas or comprising at least 60% natural gas and between 1% and 40% hydrogen gas.

[0019] In additional or alternative configurations, forming the top gas fuel from the top gas may include forming a first top gas fuel and a second top gas fuel. In some such embodiments, the top gas fuel removed utilizing the first outlet of the first top gas fuel sector may include the first top gas fuel. Furthermore or alternatively, the method may also include removing the second top gas fuel from the top gas scrubber utilizing a second outlet of a second top gas fuel sector of the top gas scrubber. Additionally or alternatively, the method may further include reducing a temperature of the second top gas fuel by spraying cooling water on packing surrounding the second outlet of the second top gas fuel sector.

[0020] In additional or alternative embodiments, the method may also include swirling unheated water within the top gas received from the shaft furnace utilizing one or more top gas inlet water injection nozzles. Furthermore or alternatively, the method may additionally include injecting unheated water within a throat of the venturi utilizing one or more venturi throat water injection nozzles. Additionally or alternatively, the method may also include reducing a water content of the first top gas fuel utilizing a mist eliminator circumscribing the first outlet. In additional or alternative configurations, the method further include reducing a water content of the second top gas fuel utilizing a mist eliminator circumscribing the second outlet. Additionally or alternatively, the method may also include reducing a water content of the venturi gas utilizing a mist eliminator circumscribing the venturi gas outlet.

[0021] In additional or alternative embodiments, the method may further include selectively combining the first top gas fuel and the second top gas fuel downstream of the top gas scrubber via control of a valve associated with a conduit coupled between the second outlet of a second top gas fuel sector and another conduit fluidly coupled to the first outlet of a first top gas fuel sector. In some such embodiments or different embodiments, the tempering gas may include a combination of the first top gas fuel and the second top gas fuel. Additionally or alternatively, the method may further include controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas. Additionally or alternatively, the method may also include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising greater than 40% hydrogen gas.

[0022] Embodiments of the invention can include one or more or any combination of the above features and configurations.

[0023] Additional features, aspects, and advantages of the invention will be set forth in the detailed description of illustrative embodiments that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein. It is to be understood that both the foregoing general description and the following detailed description present various embodiments of the invention and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the accompanying drawings, in which:

[0025] FIG. 1 is a process diagram illustrating one exemplary embodiment of a DRI process utilizing a natural gas reformer and suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter;

[0026] FIG. 2 is a process diagram illustrating one exemplary embodiment of a DRI process utilizing a NG reformer with makeup H2 and suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter;

[0027] FIG. 3 is a schematic diagram illustrating one exemplary embodiment of a TGS and associated TGS system with a suitable valving arrangement, in accordance with aspects of the present subject matter;

[0028] FIG. 4 is a top plan view schematically illustrating an exemplary embodiment of a TGS showing a piping arrangement thereof, in accordance with aspects of the present subject matter;

[0029] FIG. 5 is a top plan view schematically illustrating an exemplary embodiment of a TGS showing a piping arrangement thereof in combination with a TGS system with a suitable valving arrangement, in accordance with aspects of the present subject matter;

[0030] FIG. 6A illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter;

[0031] FIG. 6B illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter;

[0032] FIG. 6C illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter;

[0033] FIG. 6D illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter; and

[0034] FIG. 6E illustrates exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter.

[0035] It will be readily apparent to those of ordinary skill in the art that aspects of illustrated embodiments may be used in any desired combinations, without limitation. Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.DETAILED DESCRIPTION

[0036] The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the representative embodiments set forth herein. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. It is envisioned that other embodiments may perform similar functions and / or achieve similar results. Any and all such equivalent embodiments and examples are within the scope of the present invention and are intended to be covered by the appended claims.

[0037] The exemplary embodiments are provided so that this disclosure will be both thorough and complete and will fully convey the scope of the invention and enable one of ordinary skill in the art to make, use, and practice the invention. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0038] The terms “coupled,”“fixed,”“attached to,”“communicatively coupled to,”“operatively coupled to,” and the like refer to both direct coupling, fixing, attaching, communicatively coupling, and operatively coupling as well as indirect coupling, fixing, attaching, communicatively coupling, and operatively coupling through one or more intermediate components or features, unless otherwise specified herein. “Communicatively coupled to” and “operatively coupled to” can refer to physically and / or electrically related components.

[0039] The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.

[0040] As used herein, the terms “first,”“second,”“third,” and the like may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

[0041] Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and / or systems. For example, the approximating language may refer to being within a 1, 2, 4, 10, 15, or 20 percent margin.

[0042] Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0043] Again, embodiments of the present disclosure change the entire control philosophy and flow pattern of current wet scrubbing technology from a water-based control technology to a gas-based control technology and design. The incorporation of a bypass section within the scrubber design changes the basic control concept from one of trying to maintain gas temperature and humidification by inhibiting gas cooling using hot water to a design philosophy of controlling temperature and humidity simply by hot and cold gas mixing in the proper controlled proportion. In previous designs, the control relied on having hot enough packing spray water to hold the heat in the gas and trim the outlet gas to the desired temperature and humidity. The issue with such prior methods is that it requires that either the entire water system be heated up to the needed temperature for gas conditioning control or, at the very least, a large portion of the water would have to be selectively heated. This heating requires many hours and sometimes days and, in the most extreme of weather conditions, is not even possible. These prior methods also possess a built-in time lag, as the entire packed portion of the scrubber must equilibrate under new water conditions for the control system to assess the need to apply more hot or cold water to achieve the target exit gas conditions.

[0044] Various embodiments of the present disclosure remove the reliance on the water temperature to heat the system up to or beyond a desired outlet control temperature and humidity. For instance, embodiments of the concept disclosed herein may rely exclusively on the heat carried into the top gas scrubber with the entering gas to provide all the energy needed to reach the target temperature and humidity. Such functionality allows the top gas scrubber outlet temperature and humidity to be almost instantly changed by simply controlling the temperature control valve (TCV) that regulates the mixing ratio of a hot venturi exit gas to a cold process gas, thereby adjusting the desired mixed process gas temperature and humidity in the time it takes to stroke the valve change.

[0045] Embodiments of the disclosed top gas scrubber include three internal chambers that provide all the flexibility to address the process control and operating needs of the near-stoichiometric reformer within one vessel. Such a three-chamber design simplifies water draining and pressure sealing of the system and provides for more precise optimization of the design of the packing surface area and the mist removal efficiency.

[0046] Embodiments of the present disclosure significantly improve upon conventional solutions that rely on slow moving controls, heat transfer from a large heat source that is hard to get enough energy into, provide less flow flexibility (operable in a much smaller range), and utilize 30% more water, which further introduces issues related to recycling and pumping such excess water. Embodiments of the disclosed top gas scrubber (TGS) design of the present disclosure eliminate the need for a hot water well, hot water pumps, and any hot water piping, as non-limiting examples. For example, a recirculating water system load in a typical plant may be reduced by more than 700 m3 / h. Particularly and for some embodiments, the venturis and packing sprays disclosed here may be run on cold water only. The elimination of the need for heated water also eliminates inefficiencies and time wasted waiting for prior art water system to heat up. By implementation of the disclosed subject matter, reforming may be initiated as soon as a furnace burden is hot enough to support reduction, which holds true for re-starts and cold start-ups.

[0047] Referring now generally to the drawings, FIG. 1 illustrates an exemplary embodiment of a DRI process utilizing a natural gas reformer and suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter. It will be appreciated that the exemplary direct reduced iron processes and systems depicted and described herein are by way of example only, and, in other exemplary embodiments, the DRI process, system, shaft furnace, plant, or the like may have any other suitable configuration. One or more of the method elements disclosed herein may be utilized in a suitable process for the direct reduction of iron and incorporated in any suitably configured direct reduction process, system, shaft furnace, or the like. It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently.

[0048] As shown in the exemplary direct reduction system and associated process / method (system / method 100) with a natural gas (NG) reformer 12 illustrated in FIG. 1, the SF 1 may generally receive an iron oxide 2 at the top and discharges the product DRI 3 from the bottom. The top gas 4 from the SF 1, which is the spent gas after the reduction of the iron oxide, generally contains the reaction product, such as H2O and CO2, as well as the unused reductant, such as H2, CO, and CH4. After the top gas 4 is cooled and cleaned with a scrubber 5, most of cleaned process gas 7 is recycled to the SF 1 through the reduction gas loop since it still contains H2 and CO. What is called the top gas fuel 6, which is the excess gas caused by the volume expansion via NG reforming, is removed from the reduction gas loop and combusted as reformer burner fuel with the addition of makeup burner fuel gas 20, as required. Makeup NG 16 is added to the cleaned process gas 7 downstream of a compressor 8, and a mixed gas stream 9 may be preheated with a preheater 10. A preheated feed gas 11 may be fed to the reformer tubes containing a catalyst in the reformer 12, which enhances the reforming reaction of the methane derived from the NG to produce H2 and CO for the reductant of the iron oxide. Enrichment NG 18 and oxygen 19 may optionally be added to the reformed gas 13 to increase CH4 content and temperature, before feeding a resulting bustle gas 14 to the SF 1. Carburizing hydrocarbon gas 17 may be injected in a transition zone of the SF 1, which is located below the bustle gas 14 injection level, to carburize the DRI product 3 of the SF 1. In various embodiments disclosed herein, the transition zone may be defined as the portion of the SF 1 below injection of the bustle gas 14 and at or above injection of the carburizing hydrocarbon gas 17. All bustle gas 14 injected through the main bustle ports located in the lower section of the SF 1 or below the reduction zone flows upward through the iron oxide bed.

[0049] FIG. 2 illustrates an exemplary embodiment of a DRI process utilizing a natural gas reformer and makeup H2 suitable for use with embodiments of the TGS disclosed herein, in accordance with aspects of the present subject matter. It will be appreciated that the exemplary direct reduced iron processes and systems depicted and described herein are by way of example only, and, in other exemplary embodiments, the DRI process, system, shaft furnace, plant, or the like may have any other suitable configuration. One or more of the method elements disclosed herein may be utilized in a suitable process for the direct reduction of iron and incorporated in any suitably configured direct reduction process, system, shaft furnace, or the like. It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently.

[0050] As shown in the exemplary direct reduction system and associated process / method (system / method 200) illustrated in FIG. 2, the system / method 200 may generally be configured similar to the embodiment of system / method 100 described above with respect to FIG. 1. However, a substantial difference with respect to FIG. 1 is to add makeup H2 50 to the reduction gas loop as makeup H2 to process gas 92 and / or optional makeup H2 gas 91 to reformed gas 13, so that makeup H2 50 will flexibly replace a part of NG makeup 16 or H2 / CO reformed from NG with reformer 12 (e.g., reformed gas 13) to reduce CO2 emission from the direct reduction plant, depending on H2 availability. Or, the direct reduction plant with a NG reformer 12 can startup only with NG 16, but later the available amount of makeup H2 16 can be flexibly added to replace makeup NG 16 when H2 becomes available.

[0051] Referring now to FIGS. 3-4, FIG. 3 schematically illustrates an exemplary embodiment of a TGS system illustrating a valving arrangement suitable for use with embodiments of the TGS, in accordance with aspects of the present subject matter; and FIG. 4 schematically illustrates a top plan view of an exemplary embodiment of a TGS showing a piping arrangement thereof, in accordance with aspects of the present subject matter.

[0052] The embodiment of the TGS system illustrated in FIG. 3 and TGS of FIG. 4 may be utilized with the exemplary embodiment of the DRI system / method 100 illustrated in FIG. 1, a similar DRI system / method with a NG reformer, the DRI system / method 200 illustrated in FIG. 2, or a similar DRI system / method utilizing a NG reformer and makeup H2, as non-limiting examples. It should be appreciated that the disclosed TGS system may be utilized in conjunction with any suitable DRI process, system, shaft furnace, plant, or the like. One or more of the method elements disclosed herein may be utilized in a suitable process for the direct reduction of iron and incorporated in any suitably configured direct reduction process, system, shaft furnace, or the like. It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently.

[0053] As shown, the TGS 5 may include a top gas inlet 322 for receiving a top gas 4 from a SF 1. Furthermore, the TGS 5 generally includes a venturi 424 (reference number omitted from FIG. 3 for clarity) fluidly coupled between the top gas inlet 322 and each of a venturi gas sector 426 (or a venturi outlet 428 thereof), a first top gas fuel sector 430 (or a first outlet 432 thereof), and a second top gas fuel sector 434 (or a second outlet 436 thereof). Furthermore and as shown particularly in FIG. 4, the TGS 5 may include multiple internal flow dividers, baffle walls, or the like (baffle walls 437) separating such sectors 426, 430, 434 and / or the flowpaths thereof. For example, three baffle walls 437 may be arranged within the interior of the TGS 5, and each baffle wall 437 may separate two of the venturi gas sector 426, the first top gas fuel sector 430, and the second top gas fuel sector 434.

[0054] In the exemplary TGS system 300 illustrated in FIG. 3 and / or TGS 5 of FIG. 4, the need for a hot water generation / supply within the DR plant and / or system may be entirely eliminated. However and as shown particularly in FIG. 3, the TGS system 300 and TGS 5 may include one or more top gas inlet water injection nozzles (omitted from FIG. 4 for simplicity) for swirling unheated water and / or H2O (swirl water 338) within the top gas 4 received from the SF 1 at the top gas inlet 324 of the top gas scrubber 5. Additionally or alternatively, the TGS system 300 and TGS 5 may include one or more venturi throat water injection nozzle (omitted from FIG. 4 for simplicity) configured to inject unheated water and / or H2O (throat water 340) within a throat of the venturi 424.

[0055] As shown, the venturi sector 426 generally includes the venturi outlet 428 for removal of a hot venturi gas (venturi gas 342) formed from the top gas 4 received from the SF 1. It should be appreciated that the venturi sector 426 and / or the venturi outlet 428 may be appropriately sized and / or configured for the flow of the venturi gas 342. It should be appreciated that, in several embodiments, the venturi sector 426 may not include packing and cooling nozzles included in the other sectors 430, 434, as described herein. However and as shown in FIG. 4, the venturi outlet sector 422 may include a mist eliminator 444 circumscribing the venturi outlet 428 and configured to reduce a water content of the hot venturi gas 342. In some embodiments, the mist eliminator 444 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 444 may additionally or alternatively include any other configuration suitable to reduce the water content of the hot venturi gas 342. It should also be appreciated that the mist eliminator 444 may be appropriately sized for the flow of the hot venturi gas 342. Generally, the venturi gas 342 may be directed through the mist eliminator 444 without being contacted by any water other than the swirl water 338 and throat water 340.

[0056] Referring still generally to FIGS. 3-4, the first top gas fuel sector 430 generally includes the first outlet 432 for removal of a first top gas fuel 346 formed from the top gas 4 received from the SF 1. It should be appreciated that the first top gas fuel sector 430 and / or the first outlet 432 may be appropriately sized and / or configured for the flow of the first top gas fuel 346. The first top gas fuel 346 generally has a lower temperature than the hot venturi gas 342 removed from the TGS 5 utilizing the venturi sector 426 and / or the venturi outlet 428. For example and in some embodiments, the first top gas fuel sector 430 may include packing 448 surrounding the first outlet 432 and cooling nozzles (omitted from FIGS. 3-4) for spraying a cooling water and / or H2O on the packing 448 surrounding the first outlet 432. In some embodiments and as shown particularly in FIG. 4, the first top gas fuel sector 430 may include a mist eliminator 450 circumscribing the first outlet 432 and configured to reduce a water content of the first top gas fuel 346. In some embodiments, the mist eliminator 450 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 450 may additionally or alternatively include any other configuration suitable to reduce the water content of the first top gas fuel 346. It should also be appreciated that the area and / or volume of the packing 448 and the mist eliminator 450 may be appropriately sized for the flow of the first top gas fuel 346.

[0057] As further illustrated, the second top gas fuel sector 434 generally includes the second outlet 436 for removal of a second top gas fuel 352 formed from the top gas 4 received from the SF 1. It should be appreciated that the second top gas fuel sector 434 and / or the second outlet 436 may be appropriately sized and / or configured for the flow of the second top gas fuel 352. The second top gas fuel 352 generally has a lower temperature than the hot venturi gas 342 removed from the TGS 5 utilizing the venturi sector 426 and / or the venturi outlet 428. For example and in some embodiments, the second top gas fuel sector 434 may include packing 454 surrounding the second outlet 436 and cooling nozzles (omitted from FIGS. 3-4) for spraying a cooling water and / or H2O on the packing 454 surrounding the second outlet 436. In some embodiments and as shown particularly in FIG. 4, the second top gas fuel sector 434 may include a mist eliminator 456 circumscribing the second outlet 436 and configured to reduce a water content of the second top gas fuel 352. In some embodiments, the mist eliminator 456 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 456 may additionally or alternatively include any other configuration suitable to reduce the water content of the second top gas fuel 352. It should also be appreciated that the area and / or volume of the packing 454 and the mist eliminator 456 may be appropriately sized for the flow of the second top gas fuel sector 434.

[0058] Referring now to FIG. 5, FIG. 5 schematically illustrates a top plan view of an exemplary embodiment of a TGS showing a piping arrangement thereof in combination with a TGS system illustrating a valving arrangement suitable for use with embodiments of the TGS, in accordance with aspects of the present subject matter. It should be appreciated that the TGS illustrated in FIG. 5 may be configured the same or similar to the TGS 5 illustrated and described with respect to FIG. 4, e.g., including venturi gas sector, a first top gas fuel sector, and a second top gas fuel sector. However, various of the reference numbers of FIG. 4 associated with the components thereof are omitted from FIG. 5 for clarity.

[0059] Referring now predominantly to FIGS. 3 and 5, the TGS system 300 may include a process gas conduit or an assembly of process gas conduit sections (process gas conduit 558 of FIG. 5) coupled to the venturi outlet 428 of the venturi gas outlet sector 426 and configured to selectively provide the hot venturi gas 342 for use as the process gas 7 in a DRI process, after optional supplementation as described herein. As shown, the TGS system 300 may include a ranging valve 360 (e.g., as an inline valve and / or coupled between sections of a multi-section process gas conduit 558). The ranging valve 360 generally fluidly couples the venturi outlet 428 of the venturi gas outlet sector 426 to a temperature control valve (368 as described in more detail below), the flow of the process gas 7, and / or to a compressor 8. Additionally or alternatively, ranging valve 360 may allow for controlled altering of the amount of the hot venturi gas 342 flown through the downstream portions of the process gas conduit 558.

[0060] The TGS system 300 may may also include a combined top gas fuel conduit or an assembly of combined top gas fuel conduit sections (combined top gas fuel conduit 562 of FIG. 5) fluidly coupled to the first outlet 432 of the first top gas fuel sector 430. The combined top gas fuel conduit 562 is generally configured to provide the first top gas fuel 346, after optional supplementation with the second top gas fuel 352, as top gas fuel 6 to be utilized a burner fuel for combustion in the associated DRI process. Thus, it should be appreciated that the top gas fuel 6 and / or burner fuel may include the first top gas fuel 346 and / or the second top gas fuel 352. In some embodiments, the combined top gas fuel conduit 562 may be selectively fluidly coupled to the second outlet 436 of the second top gas fuel sector 434. For example, TGS system 300 may may further include a second top gas fuel conduit or an assembly of second top gas fuel conduit sections (second top gas fuel conduit 564) coupled between the second outlet 436 of the second top gas fuel sector 434 and the combined top gas fuel conduit 562. A second top gas fuel valve 366 may be controllable to selectively fluidly couple the combined top gas fuel conduit 562 and the second outlet 436 of the second top gas fuel sector 434.

[0061] Referring still predominantly to FIGS. 3 and 5, the TGS system 300 may may also include a temperature control valve 368 coupled between the process gas conduit 558 and the combined top gas fuel conduit 562. The temperature control valve 368 may be controllable to selectively fluidly couple the process gas conduit 558 and the combined top gas fuel conduit 562. Additionally or alternatively, the temperature control valve 368 may be controllable to alter an amount of the top gas fuel 6, the first top gas fuel 346, the second top gas fuel 352, and / or burner fuel bypassed to the process gas conduit 558 to cool the hot venturi gas 346 and / or resulting process gas 7.

[0062] As also shown, the top gas fuel 6 and / or burner fuel or at least a portion 6a thereof may be subsequently provided to the top gas fuel line for subsequent combustion in the DRI process, e.g., as burner fuel for a suitable reformer. A suitable valve, pressure control valve, or the like (PCV valve 370) may selectively provide the top gas fuel 6 and / or the portion 6a thereof to the top gas fuel line and / or alter an amount of such top gas fuel 6, 6a provided to the top gas fuel line. Optionally and as shown, a suitable valve, pressure control valve, or the like (PCV valve 372) may optionally provide another portion 6b of the top gas fuel 6 to a flare system for combustion as needed for emergency or operational safety release. Additionally or alternatively, the process gas line for communicating process gas 7 may include a mist eliminator 374 (FIG. 3) configured to reduce a water content of the process gas 7. In some embodiments, the mist eliminator 374 may be configured as a normal spin vane mist eliminator. In other embodiments, the mist eliminator 374 may additionally or alternatively include any other configuration suitable to reduce the water content of the process gas 7. It should also be appreciated that the mist eliminator 374 may be appropriately sized for the flow of the process gas 7.

[0063] Generally, the hot venturi gas 342 may be much higher in temperature than any required process gas 7 temperature. Thus, the hot venturi gas 342 may be tempered with the top gas fuel 6, the first top gas fuel 346, and / or the second top gas fuel 352 to achieve the same or similar temperature and humidity in the process gas 7 that would have previously been achieved by employing packing and hot water. Even if one assumes the use of top gas (TG) waste heat recovery on the venturi top gas inlet 322 reducing the venturi inlet gas to 200° C. (normally 350-400° C.) and the throat water 340 coming into the venturi at 15° C., the hot venturi gas 342 may still exit the TGS 5 at a gas temperature of approximately 65-75° C. (16-18 mol % H2O). Even in a worst-case scenario, there is sufficient heat in the top gas 4 to keep the hot venturi gas 342 above a temperature required for the process gas 7 under all known reformer operating conditions. Embodiments of the present application temper the hot venturi gas 342 with the cooler and / or conditioned top gas fuel 6 to arrive at target conditions for process gas 7 (e.g., temperature and / or humidity) allowing for safe reformer operation (e.g., NG reformer 12 of FIGS. 1-2).

[0064] It should be appreciated that all of the top gas fuel 6, the first top gas fuel 346, and / or the second top gas fuel 352 may be cooled by flowing through the respective packing 448, 454 sprayed with only cold water, as described generally above with respect to FIG. 4. Thus, there is no required hot water supply for utilization in the packing spray water system embodiments of the present disclosure. Therefore, conditions of process gas 7 suitable for use with the reformer may be met as soon as the furnace bed of the SF 1 is hot enough to support reduction. Such embodiments may completely eliminate time often lost waiting on the water system to reach temperature in prior art top gas scrubbers and / or associated DRI systems. Furthermore, the TGS 5 and / or TGS system 300 may support a transition to the use of hydrogen (H2) into the inlet of the reformer 12 (e.g., a near-stoichiometric reformer).

[0065] Embodiments of the TGS 5 and / or TGS system 300 disclosed herein may be incorporated in a DRI process / system utilizing 100% NG (e.g., the system / method 100 described above with respect to FIG. 1 or similar) and / or in a DRI process / system utilizing at least 60% natural gas and between 1% and 40% hydrogen gas (e.g., the system / method 200 described above with respect to FIG. 2 or similar). In such embodiments, first top gas fuel 346 may pass through the first top gas fuel sector 430 sized to carry all of the top gas fuel 6, including the portion thereof diverted for cooling of the hot venturi gas 342 and / or process gas 7 to arrive at target conditions of the process gas 7. As generally described above, the packing 448 and mist eliminator 450 of the first top gas fuel sector 430 may be appropriately sized for the flow of the first top gas fuel 346 and top gas fuel 6. Similarly, mist eliminator 444 of the venturi gas sector 426 is generally appropriately sized for the flow of the hot venturi gas 342. In such use cases, the second top gas fuel valve 366 may be completely closed to fluidly isolate the combined top gas fuel conduit 562 from the second outlet 436 of the second top gas fuel sector 434.

[0066] Embodiments of the TGS 5 and / or TGS system 300 disclosed herein may alternatively be incorporated in a DRI process / system utilizing natural gas and greater than 40% hydrogen makeup gas (e.g., the system / method 200 described above with respect to FIG. 2 or similar). In such embodiments, the first top gas fuel 346 may pass through the first top gas fuel sector 430 sized to carry only a portion of the top gas fuel 6. The second top gas fuel sector 434 may be sized to carry the remainder of the top gas fuel 6 (i.e., the second top gas fuel 352). In such use cases, the second top gas fuel valve 366 may be opened to fluidly couple the combined top gas fuel conduit 562 to the second outlet 436 of the second top gas fuel sector 434 and / or to controlled to alter an amount of the second top gas fuel 352 provided to the combined top gas fuel conduit 562. Generally, the first top gas fuel sector 430 and the second top gas fuel sector 434 may be sized to together carry all of the top gas fuel 6, including the portion thereof diverted for cooling of the hot venturi gas 342 and / or process gas 7 to arrive at target conditions of the process gas 7. As generally described above, the packing 448 and mist eliminator 450 of the first top gas fuel sector 430 is generally appropriately sized for the flow of the first top gas fuel 346, and the packing 454 and mist eliminator 456 of the second top gas fuel sector 434 is generally appropriately sized for the flow of the second top gas fuel 352. Similarly, mist eliminator 444 of the venturi gas sector 426 is generally appropriately sized for the flow of the hot venturi gas 342.

[0067] Referring now to the incorporation of the TGS 5 and / or TGS system 300 in any suitable DRI process / system utilizing natural gas and potentially hydrogen make-up gas, the target gas conditions of the process gas 7 may generally be achieved via control of the temperature control valve (TCV) 368. In exemplary embodiments, TCV 368 may be controlled to alter an amount of the top gas fuel 6 bypassed from the combined top gas fuel conduit 562 into the hot venturi gas 342 of the process gas conduit 558 to achieve the target temperature and / or humidity of the process gas 7. It should be appreciated that, in several embodiments, because the top gas fuel 6 and the hot venturi gas 342 are fully saturated, such gases 6, 342 may mix well. For example, mixing components may not be required at the junction of such gases 6, 342. In a particular use case, should the TCV 368 be controlled to a fully open position prior to reaching the target temperature of the process gas 7, the ranging valve 360 of the process gas conduit 558 may be closed slightly to add more relative flow capability to the TCV 368 thereby extending a range of control of the TCV 368, as the need arises.

[0068] While omitted from the FIGS. here, it should be appreciated that a control unit, control system, controller, or the like (control unit) may provide operation control of any of the valves disclosed herein, thereby allowing for adjustment of the flow rate of the hot venturi gas 342, the second top gas fuel 352, the portion of the top gas fuel 6 bypassed to the process gas conduit 558, the top gas fuel 6 and / or burner fuel or at least a portion 6a thereof supplied to the burners of the reformer 12, and / or the another portion 6b of the top gas fuel 6 supplied to the associated flare system. In various embodiments, such control may be based, at least in part, on the temperature and / or humidity of the top gas 4 and / or process gas 7. Such control unit may generally include an electronic control unit, multiple associated control units, and / or a combination of one or more processing devices and at least one memory or memory device, as is well known in the art, communicatively coupled to any of the components described herein. Any of the process or method elements described herein may be implemented by the control unit utilizing one or more appropriate algorithms. In various embodiments, the control unit may include or be configured as one or more of a distributed control system, a temperature indication and control (TIC) system, an analysis indication and control (AIC) system, combinations thereof, or the like.

[0069] Referring now to FIGS. 6A-6E, FIGS. 6A-6E illustrate exemplary embodiments of method elements, one or more of which may be implemented in a method for treating a top gas of a DRI process utilizing a TGS, in accordance with aspects of the present subject matter. Any of such method 600 elements may, optionally, be computer-implemented, such as via a suitable control unit. Furthermore, the method 600 and / or elements thereof may be utilized to control or in association with any of the embodiments of the DRI system 100, the DRI system 200, SF 1, TGS 5, TGS system 300, components thereof described herein, or any other suitably configured DRI SF, system, process, plant, TGS, TGS system, or the like.

[0070] Referring now predominantly to FIG. 6A, the method 600 may include receiving the top gas from a shaft furnace utilizing a top gas inlet of the top gas scrubber (method element 602). The method 600 may further include swirling unheated water within the top gas received from the shaft furnace utilizing at least one top gas inlet water injection nozzle (method element 604). The method 600 may additionally include flowing the top gas through a venturi of the top gas scrubber (method element 606). Some embodiments of the method 600 may include injecting unheated water within a throat of the venturi utilizing at least one venturi throat water injection nozzle (method element 608). Some embodiments of the method 600 include forming a venturi gas and a top gas fuel from the top gas flown through the venturi (method element 610). Additionally or alternatively, the method 600 may include forming a venturi gas, a first top gas fuel, and a second top gas fuel from the top gas flown through the venturi (method element 612). The method 600 may also include removing the venturi gas from the top gas scrubber utilizing a venturi outlet of a venturi gas outlet sector of the top gas scrubber (method element 614).

[0071] Referring now predominantly to FIG. 6B, the method 600 may include reducing a water content of the venturi gas utilizing a mist eliminator circumscribing the venturi gas outlet (method element 616). Additionally or alternatively, the method 600 may also include removing the top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber (method element 618). In some embodiments of the method 600 may include reducing a temperature of the top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector (method element 620). The method 600 may further include reducing a water content of the top gas fuel utilizing a mist eliminator circumscribing the first outlet (method element 622). Additionally or alternatively, the method 600 may include removing the first top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber (method element 624).

[0072] Referring now predominantly to FIG. 6C, in additional or alternative embodiments, the method 600 may include reducing a temperature of the first top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector (method element 626). In additional or alternative embodiments, the method 600 may include reducing a water content of the first top gas fuel utilizing a mist eliminator circumscribing the first outlet (method element 628). Some embodiments of the method 600 may include removing the second top gas fuel from the top gas scrubber utilizing a second outlet of a second top gas fuel sector of the top gas scrubber (method element 630). The method 600 may further include reducing a temperature of the second top gas fuel by spraying cooling water on packing surrounding the second outlet of the second top gas fuel sector (method element 632). Additionally or alternatively, the method 600 may include reducing a water content of the second top gas fuel utilizing a mist eliminator circumscribing the second outlet (method element 634).

[0073] Referring now predominantly to FIG. 6D, the method 600 may include selectively combining the first top gas fuel and the second top gas fuel downstream of the top gas scrubber via control of a valve associated with a conduit coupled between the second outlet of a second top gas fuel sector and another conduit fluidly coupled to the first outlet of a first top gas fuel sector (method element 636). The method 600 may also include tempering a temperature of the venturi gas downstream of the venturi outlet utilizing tempering gas comprising a portion of the top gas fuel and thereby form a process gas for use in the direct reduced iron process (method element 638). Some embodiments of the method 600 may include controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas (method element 640).

[0074] Referring now predominantly to FIG. 6E, the method 600 may further include supplying, via a PCV, a portion of the top gas fuel to a flare system for combustion as needed for emergency or operational safety release and control, via the PCV, an amount of the portion of the top gas fuel supplied to the flare system (method element 642). Additionally or alternatively, the method 600 may include altering, via a pressure control valve (PCV) an amount of top gas fuel or a portion thereof provided to the top gas fuel line as burner fuel for a reformer (method element 644). The method 600 may also include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising only natural gas or comprising at least 60% natural gas and between 1% and 40% hydrogen gas (method element 646). In some such embodiments, the top gas fuel may only include the first top gas fuel. In alternative embodiments, the method 600 may include supplementing the process gas downstream of the top gas scrubber with makeup gas comprising greater than 40% hydrogen gas (method element 648). In some such embodiments, the top gas fuel may include both the first top gas fuel and the second top gas fuel. Embodiments of the method 600 may also include utilizing the process gas downstream of the top gas scrubber as a reducing gas in a direct reduction shaft furnace (method element 650). It should be appreciated that the process gas may be further processed (e.g., in a preheater, a reformer, a natural gas reformer, etc.) and / or may be further supplemented before being injected and counterflown within the direct reduction shaft furnace.

[0075] It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially.

[0076] Again, embodiments of the present disclosure change the entire control philosophy and flow pattern of current wet scrubbing technology from a water-based control technology to a gas-based control technology and design. The incorporation of a bypass section within the scrubber design changes the basic control concept from one of trying to maintain gas temperature and humidification by inhibiting gas cooling using hot water to a design philosophy of controlling temperature and humidity simply by hot and cold gas mixing in the proper controlled proportion. In previous designs, the control relied on having hot enough packing spray water to hold the heat in the gas and trim the outlet gas to the desired temperature and humidity. The issue with such prior methods is that it requires that either the entire water system be heated up to the needed temperature for gas conditioning control or, at the very least, a large portion of the water would have to be selectively heated. This heating requires many hours and sometimes days and, in the most extreme of weather conditions, is not even possible. These prior methods also possess a built-in time lag, as the entire packed portion of the scrubber must equilibrate under new water conditions for the control system to assess the need to apply more hot or cold water to achieve the target exit gas conditions.

[0077] Various embodiments of the present disclosure remove the reliance on the water temperature to heat the system up to or beyond a desired outlet control temperature and humidity. For instance, embodiments of the concept disclosed herein may rely exclusively on the heat carried into the top gas scrubber with the entering gas to provide all the energy needed to reach the target temperature and humidity. Such functionality allows the top gas scrubber outlet temperature and humidity to be almost instantly changed by simply controlling the temperature control valve (TCV) that regulates the mixing ratio of a hot venturi exit gas to a cold process gas, thereby adjusting the desired mixed process gas temperature and humidity in the time it takes to stroke the valve change.

[0078] Embodiments of the disclosed top gas scrubber include three internal chambers that provide all the flexibility to address the process control and operating needs of the near-stoichiometric reformer within one vessel. Such a three-chamber design simplifies water draining and pressure sealing of the system and provides for more precise optimization of the design of the packing surface area and the mist removal efficiency.

[0079] Embodiments of the present disclosure significantly improve upon conventional solutions that rely on slow moving controls, heat transfer from a large heat source that is hard to get enough energy into, provide less flow flexibility (operable in a much smaller range), and utilize 30% more water, which further introduces issues related to recycling and pumping such excess water. Embodiments of the disclosed top gas scrubber (TGS) design of the present disclosure eliminate the need for a hot water well, hot water pumps, and any hot water piping, as non-limiting examples. For example, a recirculating water system load in a typical plant may be reduced by more than 700 m3 / h. Particularly and for some embodiments, the venturis and packing sprays disclosed here may be run on cold water only. The elimination of the need for heated water also eliminates inefficiencies and time wasted waiting for prior art water system to heat up. By implementation of the disclosed subject matter, reforming may be initiated as soon as a furnace burden is hot enough to support reduction, which holds true for re-starts and cold start-ups.

[0080] Although the present disclosure is illustrated and described with reference to embodiments and examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and / or achieve like results. All such equivalent embodiments and examples are within the scope of the present disclosure, are contemplated thereby, and are intended to be covered by the following, non-limiting Claims for all purposes.

Examples

Embodiment Construction

[0036]The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the representative embodiments set forth herein. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. It is envisioned that other embodiments may perform similar functions and / or achieve similar results. Any and all such equivalent embodiments and examples are within the scope of the present invention and are intended to be covered by ...

Claims

1. A top gas scrubber for use in a direct reduced iron process, the top gas scrubber comprising:a top gas inlet configured to receive a top gas from a shaft furnace;a venturi gas outlet sector having a venturi outlet configured to remove a hot venturi gas formed from the top gas;a first top gas fuel sector having a first outlet configured to remove a first top gas fuel formed from the top gas and having a lower temperature than the hot venturi gas;a second top gas fuel sector having a second outlet configured to remove a second top gas fuel formed from the top gas and having a lower temperature than the hot venturi gas; anda venturi fluidly coupled between the top gas inlet and each of the venturi outlet, the first outlet, and the second outlet.

2. The top gas scrubber of claim 1, further comprising:a combined top gas fuel conduit fluidly coupled to the first outlet of the first top gas fuel sector and selectively fluidly coupled to the second outlet of the second top gas fuel sector,wherein the combined top gas fuel conduit is configured to provide a burner fuel for combustion in the direct reduced iron process, the burner fuel comprising at least one of the first top gas fuel or the second top gas fuel.

3. The top gas scrubber of claim 2, further comprising:a second top gas fuel conduit coupled between the second outlet of the second top gas fuel sector and the combined top gas fuel conduit; anda second top gas fuel valve configured to selectively fluidly couple the combined top gas fuel conduit and the second outlet.

4. The top gas scrubber of claim 2, further comprising:a process gas conduit coupled to the venturi outlet of the venturi gas outlet sector and configured to selectively provide a process gas for use in the direct reduced iron process; anda temperature control valve coupled between the process gas conduit and the combined top gas fuel conduit, the temperature control valve configured to selectively fluidly couple the process gas conduit and the combined top gas fuel conduit and alter an amount of the burner fuel bypassed to the process gas conduit to cool the process gas.

5. The top gas scrubber of claim 2, further comprising:a ranging valve fluidly coupled between the venturi outlet of the venturi gas outlet sector and the temperature control valve and configured to alter an amount of the hot venturi gas provided to the process gas conduit.

6. The top gas scrubber of claim 1, wherein,the first top gas fuel sector further comprises packing surrounding the first outlet and cooling nozzles configured to spray a cooling water on the packing; andthe second top gas fuel sector further comprises packing surrounding the second outlet and cooling nozzles configured to spray a cooling water on the packing.

7. The top gas scrubber of claim 1, further comprising:three baffle walls within the interior of the top gas scrubber, each baffle wall configured to separate two of the venturi gas outlet sector, the first top gas fuel sector, and the second top gas fuel sector.

8. The top gas scrubber of claim 1, further comprising:at least one top gas inlet water injection nozzle configured to swirl unheated water within the top gas received from the shaft furnace at the top gas inlet of the top gas scrubber; andat least one venturi throat water injection nozzle configured to inject unheated water within a throat of the venturi.

9. The top gas scrubber of claim 8, wherein,the first top gas fuel sector further comprises a mist eliminator circumscribing the first outlet and configured to reduce a water content of the first top gas fuel;the second top gas fuel sector further comprises a mist eliminator circumscribing the second outlet and configured to reduce a water content of the second top gas fuel; andthe venturi gas outlet sector further comprises a mist eliminator circumscribing the venturi outlet and configured to reduce a water content of the hot venturi gas.

10. A method of treating a top gas of a direct reduced iron process utilizing a top gas scrubber, the method comprising:receiving the top gas from a shaft furnace utilizing a top gas inlet of the top gas scrubber;flowing the top gas through a venturi of the top gas scrubber;forming a venturi gas and a top gas fuel from the top gas flown through the venturi;removing the venturi gas from the top gas scrubber utilizing a venturi outlet of a venturi gas outlet sector of the top gas scrubber;removing the top gas fuel from the top gas scrubber utilizing a first outlet of a first top gas fuel sector of the top gas scrubber; andtempering a temperature of the venturi gas downstream of the venturi outlet utilizing tempering gas comprising a portion of the top gas fuel and thereby form a process gas for use in the direct reduced iron process.

11. The method of claim 10, further comprising:reducing a temperature of the top gas fuel removed from the first outlet of the first top gas fuel sector by spraying cooling water on packing surrounding the first outlet of the first top gas fuel sector.

12. The method of claim 10, further comprising:controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas.

13. The method of claim 10, further comprising:supplementing the process gas downstream of the top gas scrubber with makeup gas comprising only natural gas or comprising at least 60% natural gas and between 1% and 40% hydrogen gas.

14. The method of claim 10, wherein forming the top gas fuel from the top gas comprises forming a first top gas fuel and a second top gas fuel, and wherein the top gas fuel removed utilizing the first outlet of the first top gas fuel sector comprises the first top gas fuel, the method further comprising:removing the second top gas fuel from the top gas scrubber utilizing a second outlet of a second top gas fuel sector of the top gas scrubber.

15. The method of claim 14, further comprising:reducing a temperature of the second top gas fuel by spraying cooling water on packing surrounding the second outlet of the second top gas fuel sector.

16. The method of claim 14, further comprising:swirling unheated water within the top gas received from the shaft furnace utilizing at least one top gas inlet water injection nozzle;injecting unheated water within a throat of the venturi utilizing at least one venturi throat water injection nozzle;reducing a water content of the first top gas fuel utilizing a mist eliminator circumscribing the first outlet;reducing a water content of the second top gas fuel utilizing a mist eliminator circumscribing the second outlet; andreducing a water content of the venturi gas utilizing a mist eliminator circumscribing the venturi gas outlet.

17. The method of claim 14, further comprising:selectively combining the first top gas fuel and the second top gas fuel downstream of the top gas scrubber via control of a valve associated with a conduit coupled between the second outlet of a second top gas fuel sector and another conduit fluidly coupled to the first outlet of a first top gas fuel sector.

18. The method of claim 17, wherein the tempering gas comprises a combination of the first top gas fuel and the second top gas fuel.

19. The method of claim 18, further comprising:controlling, via a temperature control valve, a temperature of the process gas by altering an amount of the tempering gas utilized to temper the temperature of the venturi gas.

20. The method of claim 19, further comprising:supplementing the process gas downstream of the top gas scrubber with makeup gas comprising greater than 40% hydrogen gas.

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