Patent Application
20130154168
The present invention generally relates to material processing, and more specifically, to the dry processing of slag and thermal recovery during said processing.
Each day, industries such as the steel industry generate hundreds of thousands of tons of slag. Steel slag, for instance, is currently finding more application in the cement industry and as an aggregate. However, conventional processes require millions of tons of water and dangerous handling to process the slag. The processing of steel slag, for example, has a considerable negative environmental impact and requires substantial expense. Accordingly, while slag contains significant amounts of thermal energy, metals, and minerals, a large percentage of the slag ends up in “slag heaps” and landfills, leaching toxins into the environment in some cases. As such, slag is a significant expense to the steel industry and a liability to the environment.
Certain embodiments of the present invention may provide solutions to the problems and needs in the art that have not yet been fully identified, appreciated, or solved by current slag processing and thermal recovery technologies. For example, some embodiments of the present invention facilitate economical dry processing of, and thermal recovery from, slag.
In one embodiment, an apparatus includes a disk assembly configured to process material. The apparatus also includes one or more heat exchangers configured to extract heat that is already present in the material, heat generated during processing, or both. The apparatus further includes a thermal transfer system configured to transfer heat away from the disk assembly, away from the one or more heat exchangers, or both.
In another embodiment, a heat transfer system includes a disk assembly, a plurality of static heat exchangers, and a manifold operably connected to the heat exchangers. The heat transfer system also includes a proximity heat exchanger configured to extract heat from the manifold and the disk assembly, and a shaft operably connected to the disk assembly and configured to rotate the disk assembly. The shaft is configured to transfer heat collected by the proximity heat exchanger away from the heat transfer system.
In yet another embodiment, an apparatus includes a disk configured to rotate and pulverize the slag and to create a central vortex in the slag. The apparatus also includes a plurality of supports operably connected to the disk that are configured to create vortexes at or near a boundary layer of the central vortex. The apparatus further includes a plurality of static heat exchangers configured to extract heat from the slag and a manifold operably connected to the plurality of static heat exchangers. Additionally, the apparatus includes a proximity heat exchanger configured to extract heat from the manifold and the plurality of supports and a shaft configured to rotate the disk and the plurality of supports, and to transfer heat collected by the proximity heat exchanger. The disk, one or more of the supports, one or more of the plurality of static plate-like heat exchangers, or a combination thereof, include a plurality of holes on one or more of their respective surfaces, and the holes are configured to distribute air into the slag during processing.
For a proper understanding of the invention, reference should be made to the accompanying figures. These figures depict only some embodiments of the invention and are not limiting of the scope of the invention. Regarding the figures:
It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments, as represented in the attached figures, is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.
The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, the usage of “certain embodiments,” “some embodiments,” or other similar language, throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. Thus, appearances of the phrases “in certain embodiments,” “in some embodiments,” “in other embodiments,” or other similar language, throughout this specification do not necessarily all refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
Some embodiments of the present invention efficiently and effectively process slag, as well as recover thermal energy from the slag during processing. In some embodiments, a rotating disk creates a vortex at the bottom of a slag pot while the slag is still in its molten state. However, in some embodiments, the shape of the “disk” can vary, and any suitable shape for mixing and crushing slag, such as a diamond, an oval, etc., may be used. Further, in some embodiments, multiple disks may be used.
A plurality of supports connect the central disk to a drive mechanism. Each of these supports is designed to generate a tornado-like vortex on the leading edge and draw in air because the following edge creates a vacuum. The supports may be located so as to be at or near the vortex generated by the disk. The process takes advantage of the principle of “interparticle collision” to pulverize the slag. This process may be used to granulate and particulate materials in both solid and molten states. The temperature of the slag is rapidly reduced and thermal energy is recovered via the supports, heat exchangers, or both. In some embodiments, slag from a slag pot may be processed, and much of the thermal energy recovered therefrom, every 65-75 minutes.
Slag can be a valuable resource, as it contains significant amounts of thermal energy, as well as valuable minerals and molecularly fixed metallic fractions. Embodiments of the present invention process slag in a contained area without the use of water (i.e., dry processing), recovering a large percentage of the thermal energy and enhancing the recovery of the fixed metallic fraction of the slag with minimal additional processing. This approach to slag processing mitigates the negative environmental impact of contaminated water that results from conventional slag processing methods. The initial processing, thermal recovery, and the recovery of the fixed metallic fraction of the slag via embodiments of the present invention can change the economics of slag. Now slag such as steel slag may move from a liability to an asset; from an expense to a profit center. Further, the environmental impact of slag can be significantly reduced for several industries. The specific economics with respect to steel slag are discussed below, although embodiments of the present invention may be used for any suitable type of slag.
A forty-five ton slag pot may contain over eight megawatts of recoverable thermal energy. A typical steel plant generates thirty to forty steel pots per day, each usually weighing between thirty and sixty tons, but typically approximately forty-five tons. These pots are typically generated daily for 360 operating days a year.
Slag can be quite valuable. For example, each ton of steel slag contains hundreds to thousands of dollars of metals and minerals when processed properly. Also, steel slag can be a superior replacement for mined limestone that is currently used by the cement industry. Calcites from steel slag produce superior cement without energy-intensive clinkering as the chemical composition of these calcites can be carefully controlled to provide an identical, or nearly identical, replacement, and the calcites are already pulverized. When processed properly, slag can generate 2.5 to 6 million dollars from the sale of the metallic fraction alone, and thermal energy from the slag may be used to generate another 2.5 to 6 million dollars of electrical energy. Further, the following metal chlorides can commonly be produced from steel slag: ferric chloride, ferrous chloride, magnesium chloride, and manganese chloride. Some of the elements that can be recovered from stainless steel slag, for example, include: aluminum, antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, phosphorus, selenium, silicon, silver, sodium, thallium, and zinc.
Many embodiments of the present invention employ a dry process to extract thermal energy from over 1450° Celsius (C.) to 350° C. while pulverizing the slag, rapidly reducing the temperature and changing the physical characteristics of the slag. Some embodiments use a solid state thermal transfer system to extract thermal energy and a disk assembly (including a disk and multiple supports) to generate a central vortex in the slag. Per the above, each support also generates its own vortex. This operation combines the phenomenon of interparticle collision with mechanical grinding after weakening the structural strength of the slag with the physical actions of aeration and thermal shock. This substantially changes the physical characteristics of the slag from an amorphous plasticized mass similar to solidified lava into a porous pumice-like substance. The slag is now structurally weaker and can be more easily and rapidly pulverized.
Slag processed in this manner easily absorbs water and acid solutions that can be used to dissolve metallic fractions so they can be separated and refined using available commercial processes. Once processed, high purity metals and metallic chlorides can be produced. The remaining material is primarily composed of high purity carbonates with highly cementitious characteristics. As the slag is processed, the thermal energy is recovered by a series of heat exchangers and may be transported to a thermal storage unit to be used for beneficial applications such as the generation of electricity.
Slag Processing and Thermal Extraction System
In some embodiments, disk 122 and/or supports 124 may have a Fibonacci spiral pattern crafted into the casing. Including such a pattern on the surface of these components may enhance the interaction of the vortexes. This may facilitate superior heat transfer to disk 122 and/or supports 124, and may further facilitate more rapid cooling of the slag by drawing in more air.
System 100 also includes static plate-like heat exchangers 130. However, whether the heat exchangers are static and/or plate-like is a matter of design choice. Static plate-like heat exchangers 130 may be curved to conform to the shape of slag pot 110, and may further serve to protect slag pot 110 from damage due to swiftly moving slag. In some embodiments, static plate-like heat exchangers 130 may extend deeper into slag pot 110 than disk assembly 120, or vice versa. Static plate-like heat exchangers 130 are connected to manifold 132, which collects heat from static plate-like heat exchangers 130. First proximity heat exchanger 134 keeps disk assembly 120 cool and extracts thermal energy from manifold 132 for storage and potential use for the generation of electricity, as discussed below. Shaft 136 is operably connected to disk support 126 and enables the rotation of disk assembly 120. Shaft 136 also contains a thermal transfer medium and functions to transfer heat from first proximity heat exchanger 134 to second proximity heat exchanger 138. Shaft 136 extends through manifold 132 and first proximity heat exchanger 134, which do not significantly impede rotation of shaft 136.
One or more of disk 122, supports 124, and static plate-like heat exchangers 130 may contain air holes on all or part of the component surfaces that introduce high pressure air into the slag. Some such embodiments are shown more clearly in
One advantage of introducing air in this fashion is the air may allow slag to be processed at lower rotation speeds of disk assembly 120 than is otherwise possible. Another advantage of introducing high pressure air into the system is that the density of the slag can be reduced and the system does not need to rely on the introduction of outside air during mechanical processing via vortex action alone. Yet another advantage of such embodiments is that the risk of slag escaping the pot at high rotation speeds may be reduced.
First proximity heat exchanger 134 is used to draw energy from rotating disk assembly 120 and from manifold 132. First proximity heat exchanger 134 serves two functions: (1) to keep disk 122 and supports 124 relatively cool while rotating the slag, which may be over 1500° C.; and (2) to harvest the collected thermal energy so the energy can be used to generate electricity, or for any other desired application. In some embodiments, system 100 may operate between 350-1500° C. However, the temperature of operation may vary based on the materials to be processed and the design of system 100. In some embodiments, a half of first proximity heat exchanger 134 (halves not illustrated here) may be static, while the other half rotates with disk support 126, disk 122, and supports 124 of disk assembly 120. The energy may be transferred by radiant energy as no physical contact between the plates may occur in some embodiments. Such a design would reduce wear-and-tear on first proximity heat exchanger 134 due to the lack of physical contact, and thus, reduce mechanical wear between its halves.
The lower and upper halves of first proximity heat exchanger 134 are typically within close proximity (several millimeters or less) to one another in many embodiments. Manifold 132 should generally be positioned so as to provide sufficient clearance between itself, disk support 126, and the lower half of first proximity heat exchanger 134 so as not to interfere with the operation of these components. In some embodiments, manifold 132 may be partly or completely integrated with the upper half of first proximity heat exchanger 134 since, in many embodiments, the upper half of first proximity heat exchanger 134 is static, like manifold 132.
Drive motor 140 drives the rotation of shaft 136, and thus disk assembly 120. Drive motor 140 provides the force necessary to generate the vortexes via disk 122 and supports 124. This involves accelerating the disk apparatus up to a desired rotation, maintaining a rotational speed that may exceed 1,000 rotations per minute (RPM) or more in some embodiments, and harvesting thermal energy via second proximity heat exchanger 138, which is connected to the end of shaft 136 opposite disk assembly 120. Drive motor 140 may also decelerate the rotation of shaft 136. Drive motor 140 may be an electrical motor in some embodiments, and may have a magnetic transmission 142, or may have any type of conventional transmission, such as a geared transmission, in other embodiments. Magnetic transmission 142 should be designed to be robust in harsh industrial environments and to be sufficiently able withstand the rigorous high temperature and abrasive particulate environment in which magnetic transmission 142 will operate. Vibration of both the mounting surface and the crucible should be handled by magnetic transmission 142 to reduce maintenance.
Magnetic transmission 142 may be encased to both avoid contaminating residue and to ensure that no contaminating residue collects on, or fouls, drive motor 140 or magnetic transmission 142. Magnetic transmission 142 may use a contactless magnetic gear assembly that overcomes the wear-and-tear and gear failure liabilities normally experienced in conventional gear-to-gear assemblies. Transmission lubrication may be limited to the shaft spline gear assembly in such embodiments. Lubrication service may be routinely performed once annually, for example. Per the above, in some embodiments, magnetic transmission 142 may be capable of driving shaft 136 and disk assembly 120 in excess of 1,000 RPM.
Magnetic transmission 142 may be electronically controlled and may be capable of generating varying amounts of torque despite the changing consistency of the slag. A purpose of using a magnetic transmission is to provide a continuous variable range of gear ratios (CVT). Using magnets as an integral part of the transmission (MCVT) provides a unique set of properties when compared to currently available transmissions. These include non-contact, reduced lubrication, reduced complexity, reduced mechanical loss, and reduced size. Magnetic transmission 142 may use a fraction of the energy required by mechanical transmissions, has few mechanical parts to wear out, and may be totally interactive, allowing more torque to be supplied to shaft 136 and disk assembly 120 to rapidly particulate the solidifying slag at a rate directly proportional to the resistance of the slag.
System 100 includes a ceramic pot cover 150 that insulates slag pot 110 with first proximity heat exchanger 134. In some embodiments, ceramic pot cover 150 may incorporate an overflow barrier (not shown) to accommodate the increased volume of the aerated slag, as is shown in more detail in
A second purpose of ceramic pot cover 150 is to aid in the recovery of thermal energy. The walls of ceramic pot cover 150 may include a high temperature refractory material that easily contains 1500° C. and higher. The lining of the upper third of ceramic pot cover 150, however, may include high density silicon carbide (SiC) tiles that are filled with the static thermal transfer medium, and the tiles may interlock so the energy these tiles absorb can be collected and used for other purposes, such as generating additional steam for power generation. Yet another purpose of the containment hood is to create a stable environment for slag pot 110. As the slag in the interior of slag pot 110 is being rapidly cooled, it may be important that at no time does the temperature of slag pot 110 drop below a certain temperature, such as 300° C. in some embodiments. If outside air were allowed to cool slag pot 110 without some control, it could be difficult to control the cooling of slag pot 110. Ceramic pot cover 150 may be equipped with a thermal sensing device (not shown) and system 100 may include interactive controls that can reduce or increase the rate of thermal extraction. The hood of ceramic pot cover 150 may also open mechanical vents to allow more cool air into slag pot 110 to modify the environment.
System 100 further includes a support gantry 160 that positions slag pot 110. A locking mechanism (not shown) may be present to lock slag pot 110 in place, as is shown in more detail in
At the beginning of the cycle, support gantry 160 may lower static plate-like heat exchangers 130 and disk assembly 120 into the still molten slag to begin the processing cycle. Static plate-like heat exchangers 130 and/or disk assembly 120 may begin injecting air into the slag via a plurality of holes. At around a desired temperature, such as 1150° C. in some embodiments, disk assembly 120 begins rotating to start the pulverizing process. Once the pulverizing stops (for example, at 350° C. in some embodiments) hydraulics or other drive mechanisms of support gantry 160 raise the hood. This raises static plate-like heat exchangers 130 and disk assembly 120 from slag pot 110. Support gantry 160 may then release slag pot 100 from a locked position via a locking mechanism (not shown) to allow the finely pulverized slag to be suctioned, poured, or otherwise removed from slag pot 110 and delivered by a conveyor or other suitable mechanism to secondary cooling. In an alternative embodiment, a transport vehicle or other transport mechanism may retrieve slag pot 110 and take slag pot 110 to a desired location.
Thermal storage unit supports 170 support thermal storage unit 172. Thermal storage unit 172 may be lowered onto and off of thermal storage unit supports 170 by a gantry and crane mechanism (not shown) for transportation to other locations. Thermal storage unit 172 may be disconnected and transported to a point of use, such as a remelt area of a steel plant, in such embodiments. However, in some embodiments, thermal storage unit 172 may remain static and electrical energy and/or thermal energy may be transported via flexible cables. Second proximity heat exchanger 138 transfers heat to thermal storage unit 172 via thermal storage unit proximity heat exchanger 174. Thermal storage unit proximity heat exchanger 174 may be integrated into thermal storage unit 172.
Pulvertzing of Slag and Thermal Extraction
As disk 212 circulates and generates a torus-like vortex in the slag, thermal energy is rapidly extracted from the slag by static plate-like heat exchangers 220 and supports 214, further weakening the mechanical strength of the slag due to thermal shock that creates microfissures. While not shown here, one or more of disk 212, supports 214, and static plate-like heat exchangers 220 may have air holes to introduce high pressure air into the slag in some embodiments. In some embodiments, static plate-like heat exchangers 220 may be approximately one meter wide by two meters tall by 0.1 meters thick, although the specific size and shape is a matter of design choice. The number of supports and heat exchangers that are used, as well as whether the supports are configured to extract heat from the slag, is also a matter of design choice. Preferably, supports 214 are positioned such that they are at or near the vortex boundary layer generated by disk 212. Each of supports 214 also creates its own spiral-shaped tornado-like vortex in the slag and draw in cooler air from outside.
The thermal shock in conjunction with the vortex action causes the slag to rapidly break up into particles. These weakened particles of slag are pulverized by the “interparticle collision” caused by the action of the vortexes. As a result, the particles may be pulverized into a fine material approximately 0.2 to 2 mm in size in a relatively short time in some embodiments. However, the precise size that is obtained is a function of design and processing time.
Disk 212 may also act as a heat exchanger in some embodiments as disk 212 may be hollow and filled with a solid-state thermal transfer medium (not shown), such as graphite foam commercially manufactured and known as PocoFoam®. Supports 214 and disk support 216 may also be filled with a solid-state thermal transfer medium. Filling disk 212 and/or supports 214 with a thermal transfer medium may allow these components to operate in higher temperature environments than conventional systems as much of the heat can be transferred away from the disk and/or supports. In some embodiments, disk 212 may be approximately 1.2 m in diameter and may be supported by a plurality of supports 230 that are also filled with a solid-state thermal transfer medium (not shown) to cool disk 212 and extract thermal energy during the process. In some embodiments, shaft 226 may function as a single support and be offset from the center of the disk so as to be at or near the vortex boundary layer. However, in such embodiments, it may be necessary to create a substantially horizontal vortex and have high rotation speeds between 3,000 and 10,000 RPM to generate enough turbulence to promote interparticle collisions.
Static plate-like heat exchangers 220 are the primary thermal extraction mechanism in this embodiment, although supports 214 also extract heat energy. Static plate-like heat exchangers 220 and supports 214 may have an abrasive surface and sharp edges designed to chop and cut chunks of slag as these components contact the slag due to rotation and/or the vortex action created by the circulation of disk 212 and supports 214. The casing may be coated in several ceramics, such as boron nitride (BN) “cubic”, which has the same hardness as diamond (Moh scale 10) and is highly thermal conductive. Such coatings have been found to be stable up to 2800° C. in certain environments.
The outer case contains a central core that may be composed of a highly thermal conductive solid state medium such as graphite foam commercially manufactured and known as PocoFoam® or a similar graphite composite material with high thermal conductivity. PocoFoam®, for example, has the ability to transfer thermal energy at supersonic speed. PocoFoam® or similar graphite composite materials have high thermal conductivity equivalent to, and in some cases exceeding, the thermal conductivity of metals routinely used as heat sinks. The thermal diffusivity of such graphite composite materials may be as much as four times greater than pure copper and pure aluminum. Scanning electron microscope (SEM) and X-ray diffraction (XRD) results indicate that PocoFoam® and similar graphite composite materials with high thermal conductivity have a high degree of crystalline alignment and near theoretical d spacing that is more typical of natural flake graphite than synthetic graphite.
The core may be static and may transfer the thermal energy to a thermal storage unit or be used directly for electricity generation, depending on the temperature of the energy and the desired use. Because the relative coefficient of expansion differs, the void between the outer case and internal components may be filled with a mixture that can be compressed or expanded without loss of thermal conductivity. In some embodiments, this mixture may include SiC and BN in microspherical and nanospherical shapes, respectively. Per the above, in this embodiment, supports 214 and disk support 216 are also filled with a thermal transfer medium.
Many solid state composites can be used, such as a combination of graphite foam combined with a nanolayer of BN, considering that the theoretical thermal conductivity of hexagonal boron nitrite nanoribbons (BNNRs) can approach 1700-2000 W/(m·K). This is the same order of magnitude as the experimental measured value for graphene, another substance that can be combined with graphite to create a super thermal conductive solid state medium.
Manifold 222 is connected to static plate-like heat exchangers 220. Manifold 222 is filled with a thermal transfer medium, collects heat from static plate-like heat exchangers 220, and passes the heat through the system. Heat is transferred to proximity heat exchanger 224 and on through shaft 226. Both heat exchanger 224 and shaft 226 are filled with a thermal transfer medium and transfer heat onwards through the system.
Non-transitory computer-readable media may be any available media that can be accessed by processor 410 and may include both volatile and non-volatile media, removable and non-removable media, and communication media. Communication media may include computer-readable instructions, data structures, program modules, lookup tables, or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media.
Processor 410 is further coupled via bus 405 to a display 425, such as a Liquid Crystal Display (“LCD”), for displaying information to a user. A keyboard 430 and a cursor control device 435, such as a computer mouse, are further coupled to bus 405 to enable a user to interface with controller 400. Due to the extreme heat and potentially hazardous conditions that may be proximate to slag processing equipment, display 425, keyboard 430, and cursor control device 435 may be located separately from controller 400 and may communicate with controller 400 via wireless communication, an Ethernet cable, or any other suitable means for transmitting and/or carrying data.
In one embodiment, memory 415 stores software modules that provide functionality when executed by processor 410. The modules include an operating system 440 for controller 400. The modules further include a rotation control module 445 that is configured to control the rotation of a shaft and disk assembly. Controller 400 may include one or more additional functional modules 450 that include additional functionality.
One skilled in the art will appreciate that a “controller” could be embodied as a personal computer, a server, a console, a personal digital assistant (PDA), a cell phone, or any other suitable computing device, or combination of devices. Presenting the above-described functions as being performed by a “controller” is not intended to limit the scope of the present invention in any way, but is intended to provide one example of many embodiments of the present invention. Indeed, methods, systems and apparatuses disclosed herein may be implemented in localized and distributed forms consistent with computing technology.
It should be noted that some of the controller features described in this specification have been presented as modules in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very large scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays (FPGAs), programmable array logic, programmable logic devices, graphics processing units, or the like.
A module may also be at least partially implemented in software for execution by various types of processors. An identified unit of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions that may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module. Further, modules may be stored on a non-transitory computer-readable medium, which may be, for instance, a hard disk drive, flash device, random access memory (RAM), tape, or any other such medium used to store data.
Indeed, a module of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.
Thermal Distribution System
As discussed above, in order to facilitate heat transfer, embodiments of the present invention utilize material or materials with high thermal conductivity. In some embodiments, the material may be PocoFoam® or a similar graphite composite material. The highly thermal conductive material may be contained within the disk, heat exchangers, and an insulated heat pipe system.
All forms of heat transfer may occur simultaneously in some systems—for example, in transparent fluids. One of the driving forces of nature is the dynamic flow of energy within the environment across one or many systems to achieve a state of harmonious balance and systemic equilibrium. The driving force behind the transfer of thermal energy in many embodiments of the present invention is an existing temperature differential between two connected systems. Residual thermal energy from slag pots, or any other industrial or other thermal source for that matter, is normally released through the cooling process and typically is wasted. Embodiments of the present invention are designed to capture and harvest this residual thermal energy via a solid state thermal capture system and to transfer the thermal energy from a high temperature region to a lower temperature region or thermal storage system.
An application of heat transfer is in the thermal exchange of heat in controlled fluid and/or steam systems using pipes as a mechanically integrated system designed to transfer heat in a controlled environment using a common medium. Common to small and large scale thermal energy transfer systems is the management and control of heat transfer loss within the end-to-end system. The aggregate of thermal losses over time quantify the operational efficiency and costs of the system. Accordingly, some embodiments of the present invention incorporate system integration of an end-to-end solid transfer medium. Some embodiments may mitigate more than 90% of the thermal losses that are common in conventional systems.
Heat transfer system 500 also includes static plate-like heat exchangers 520 that are connected to manifold 522, which collects heat from static plate-like heat exchangers 520. First proximity heat exchanger 530 keeps disk assembly 510 cool and extracts thermal energy from manifold 522 for storage and potential use for generation of electricity, as discussed below. Shaft 532 is operably connected to disk support 516 and enables the rotation of disk assembly 510. Shaft 532 is also connected to second proximity heat exchanger 534. Heat is transferred upwards through the system from disk assembly 510 and static plate-like heat exchangers 520 up through heat transfer system 500 to second proximity heat exchanger 534, which may be used to transfer heat to a thermal storage unit, for example. In some embodiments, recovery of over 90% of the conducted energy and over 50% of the radiant energy from each pot of slag may be realized.
Thermal Storage Unit
Thermal storage unit 610 contains an integrated proximity heat exchanger 612 that receives heat from proximity heat exchanger 620. Proximity heat exchanger 620 is connected to shaft 622 and receives heat from the system below. Both proximity heat exchanger 620 and shaft 622 are filled with a high thermal conductivity material.
Expansive layer 720 is positioned between casing 710 and core 730. Expansive layer 720 may be comprised of a material that accommodates thermal expansion, yet facilitates high thermal conductivity and provides short-term storage between cycles. In some embodiments, expansive layer 720 may include microspheres of SiC and BN. Core 730 conducts heat and includes a highly thermal conductive material such as PocoFoam®.
While not shown in this embodiment, static plate-like heat exchanger 700 may have holes in casing 710 that permit the flow of high pressure air into the slag. This helps to aerate the slag more rapidly, and to make the slag more porous and less dense. Air may be supplied to the holes by means of tubes, channels, or any other suitable mechanism (also not shown) that flow through casing 710, expansive layer 720, or both. The air may be supplied by an air pump that is controlled by an electronic controller. Air may also be supplied in a similar fashion to one or more supports, which may have a similar architecture to static plate-like heat exchanger 700 with respect to the materials from which the supports are made.
The lower half 900 of the proximity heat exchanger may be connected to the vortex generating disk assembly by way of a frame and supports in some embodiments, and may serve the role of disk support 126 of
In this embodiment, the top half 940 of the proximity heat exchanger is not attached to shaft 930 and is static. Top half 940 may be connected by heat pipes to the thermal collection system. A hole in the middle allows shaft 930 to pass through without touching the walls. Lower half 900 can also rotate without coming into contact with upper half 940. The shape of lower half 900 and upper half 940 creates a heat trap allowing the transfer of energy between the two sections to take place by way of highly efficient radiation. In other embodiments, the top half may rotate instead, the top and bottom halves may rotate in the same or opposite directions, or both the top and bottom half may be static. However, some such configurations may potentially have inferior performance.
Heat pipe 1132 carries heat to an external source. This heat can be used to do work, to directly drive external combustor-type combined cycle gas turbines, to create steam to drive a generator in order to create electricity, or for any other suitable application. In the context of a manufacturing facility, this electricity could be used to help meet the enormous power needs of the facility itself, and/or be sent back out on the grid and sold to a utility.
As the temperature of the slag drops to between approximately 1000° C. to 350° C., thermal energy is diverted to direct steam generation at 1140. This constitutes the second stage of processing. In the second stage, the slag begins to solidify and gas bubbles get trapped in the slag, creating micropockets and making the slag pumice-like. The speed of rotation of the disk assembly slows and torque increases as the resistance increases. The moving components cut and grind the solidifying slag into smaller and smaller particles via interparticulate collision. The collisions crush and shatter the particles of slag.
This action, combined with the abrasion between the apparatus and the slag particles, make the process extremely rapid. For example, 40 tons of slag may be processed in less than 75 minutes in some embodiments. The dynamics of the process protect the slag pots and keep the pots in a carefully controlled environment. Slag pots are often made of cheaper materials such as cast iron, and as such are often less durable than the surrounding equipment. The slag pot is protected from the abrasion and heat of the process by static heat exchangers that may conform to the shape of the pot. Metal recovery is also enhanced as within the rapidly cooled rotating mass, the steel will form small beads as it solidifies, which are easily separated using an existing metal recovery system. The value of this porous slag is further enhanced as other valuable materials such the chlorides of iron, magnesium and manganese can be recovered in a separate process. This may more than double value of the total process in some embodiments.
Finally, when the temperature of the slag drops below approximately 350° C., the slag is poured into a secondary recovery system at 1150. This constitutes the third and final stage of the process. This protects the slag pot from further cooling and the remainder of the thermal energy is extracted to near ambient temperature by conventional processes which deliver this recovered energy to generate steam.
Once the slag pot and containment hood are locked into place, one or more static plate-like heat exchangers are lowered into the slag pot at 1230. Separate mechanisms may exist for lowering the containment hood, the static plate-like heat exchangers, and/or the disk assembly in some embodiments. One or more of the static plate-like heat exchangers may have holes and piping to facilitate the injection of air into the molten slag. Injection of the air produces foam and vortex rotational movement of the molten slag, and thermal energy collected by the static plate-like heat exchangers, along with energy collected by the heat exchanger of the containment hood, may be transported for thermal storage.
Once the slag is cooled to a desired temperature, such as 1150° C. in some embodiments, and once the slag density has been lowered by the foaming created by the injected air, a disk assembly is lowered into the slag at 1240. The disk assembly begins rotating and increases the velocity of the vortexes in the slag. Thermal energy is collected and transported to a thermal storage unit until the temperature drops to a desired level, such as 1000° C. in some embodiments. The thermal energy is stored in a thermal storage unit to be used to do work.
Once the temperature has dropped to the desired level, high temperature thermal energy is used to do work at 1250. As the temperature drops, thermal energy may be used to directly drive steam turbines, and energy extracted from the thermal storage unit may be used to operate combined cycle gas turbines. The processed slag is then extracted from the slag pot at 1260 and conveyed to a secondary thermal extraction unit that extracts further heat energy from the slag.
Containment hood 1430 has three hood locks 1432 that secure containment hood 1430 to slag pot 1410. A connector 1440 is operably connected to containment hood 1430 and hood hydraulics 1442. Hood hydraulics 1442 serve to lower containment hood 1430 onto, and raise containment hood 1430 off of, slag pot 1410.
Some embodiments of the present invention facilitate the dry processing of, and thermal recovery from, slag. Embodiments take advantage of the principle of interparticle collision to weaken the structure of and pulverize slag material. During the process, the slag is rapidly cooled and heat is extracted from the slag using heat exchangers and materials that conduct and transfer heat energy effectively. In many embodiments, heat may be transferred to a thermal storage unit that is capable of storing and releasing large quantities of heat energy. Accordingly, Many embodiments of the present invention are able to eliminate the environmental concerns surrounding wet processing of slag, are able to make slag a profit center, and are further able to recover much of the energy that is required to heat and process the slag.
One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.
