This invention relates to furnaces, specifically to furnaces for the conversion of waste, and more specifically to high temperature furnaces, and even more particularly to apparatus for conveying such waste to such high temperature furnaces.
For centuries, solutions have been sought as to what to do with solid waste that communities and industries tend to generate. Waste has been buried, sunk, and where possible recycled, or converted to other uses, to remove such waste from human habitation. For decades, efforts have been made to convert waste to other useful materials by the application of a high-temperature plasma arc or torch, a.k.a. pyrolytic conversion. The resulting products of this conversion include metals, and product synthesis gas, or “syngas.”
The products obtained from the plasma conversion process have many uses in other areas and so can be of value. However, the reaction should ideally be controlled in order to predict the resulting syngas composition. Variables that require the greatest control in the process include the amount and composition of solid waste, including municipal solid waste (MSW), the speed at which the waste material is fed into the furnace, the density of the material, and the amount of ambient air trapped within the material.
Most feed systems relate to waste compaction and baling systems. While these systems serve to reduce the size and increase the mass of the material that would be processed, they do not account for the air density within the material. Furthermore, they are not compatible for use with high-temperature furnaces. Feeders operating in such environments must not only include heat-tolerate components, but must include certain safety features that may prevent blow back of hot furnace gases into the feeder apparatus.
The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.
The various embodiments of the present invention and their advantages are best understood by referring to
Furthermore, reference in the specification to “an embodiment,” “one embodiment,” “various embodiments,” or any variant thereof means that a particular feature or aspect of the invention described in conjunction with the particular embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases “in one embodiment,” “in another embodiment,” or variations thereof in various places throughout the specification are not necessarily all referring to its respective embodiment. Moreover, features described with respect to a particular embodiment may also be employed in other disclosed embodiments as those skilled in the relevant arts will appreciate. This invention may be provided in other specific forms and embodiments without departing from the essential characteristics as described herein. The embodiments described below are to be considered in all aspects as illustrative only and not restrictive in any manner.
In operation, solid waste materials are dumped into the hopper 101 and fall to the opening 103. When ram 110 is extended, as shown in
At a prescribed cycle time, the ram 110 is retracted, as shown more clearly in
It should be noted that while the reduction in cross-sectional area is shown in the drawings to occur through lowering the ceiling of the throat area 119 compared to the channel 105, the same result may be obtained, as those skilled in the art will appreciate, by decreasing the side wall interior separation. For that matter, one or more restrictor plates, similar to the restrictor plate 117 may be installed on the side walls including actuators for providing lateral force to the side wall restrictor plates.
The operation of the hydraulic systems may be controlled by one or more computer systems configured with control logic to issue control commands to adjust the timing of ram 110 or actuator movement, and to adjust the force exerted (hereinafter, the “control system”). To insure a uniform, predictable density of the waste entering the furnace, the force imparted by actuator 118 is controlled such that it is inverse to the force imparted by ram 110. This may be accomplished through one or more sensors which detect the pressure exerted by the ram 110. Data from the one or more sensors is used as input to the control system which is configured with logic to evaluate the pressure data from the ram 110 and output a control signal to the actuator 118 to either increase or decrease force in order to remain inverse to the force exerted by the ram 110. For example, if the ram 110 must exert an increased amount of force to impel the waste through the channel 105, data from the one or more sensors indicates this condition, communicates it to the control system which then orders the actuator to apply decreased force to the restrictor plate 117. Conversely, if the ram exerts less force to move waste, the control system, upon receiving this data, issues a command to the actuator 118 to increase force applied to the restrictor plate 117. The result is a bolus of solid waste compacted to a density that is substantially uniform with respect other waste processed by the apparatus 10. Furthermore, air is forced from the waste and is expelled through the opening. In this way, the types and amounts of materials that result from the reaction in the plasma furnace are more predictable and controllable.
Referencing
In another embodiment, the floor 305 of the channel 105 may comprise a ridge, rib, or wall structure, on which the wheel rides, an example of which is shown at 307. The wheel guard 303 in this instance is configured with a cut-out 308 to accommodate the wall structure 307.
A version of the ram head plate 111 is depicted in elevational view in
It should also be noted that in the embodiment depicted, the channel 105 cross-section is rectangular having a greater width than height. The size of the ram head plate is dimensioned to substantially fill the channel, but preferably dimensioned to provide a clearance of about one eighth to about one fourth inch. With reference to
In another embodiment, the apparatus includes features which aid in clearing large pieces of debris from the hopper 101 and opening 103. In
In a further embodiment, shown in
Since the furnace 102, particularly when it is a plasma furnace, operates at such a high temperature, the throat area experiences such extreme temperatures. Furthermore, hot gas from the reaction chamber in the furnace may escape back into the throat area 119 which could ignite the unprocessed waste inside the throat area and channel 105. With reference to
Another possible feature of the throat structure is a series of articulated baffles 707 that are pivotally attached to the top inside of the throat area 119 and extend across the top of the throat area. These baffles 707 prevent hot gas from flowing back through the throat area from the furnace, and are articulated such that a baffle is allowed to move along with the movement of waste material being processed 709. Baffles 707 may be formed from any suitable rigid, durable, heat-tolerant material, for example, steel, stainless steel, or fiber-reinforced ceramics.
A further safety feature that may be included is a system for infusing an inert, non-reactive, displacement gas into the throat. For example, a supply of nitrogen 715 may be coupled to the throat area through a supply line 720 that has an open end within the throat 119. If there is a back up of hot gas in the throat area as a result of, for example, an increase in system pressure, a signal from the sensors 703 provides data to the control system which is configured with control logic that subsequently issues a command to release nitrogen under pressure into the throat area to displace the hot gas and force it back into the reactor.
Optionally, the compaction box 115 could include a second actuator-impelled plate 717 mounted downstream from the restrictor plate 117. This plate 717 is also pivotally attached by one side, but by the downstream side. Actuation of the second plate 717 using an actuator 718 further compacts the material and helps to insure continued forward movement of the debris toward the reactor chamber.
With reference to
In yet another embodiment, and with reference to
The material is forced past the dogs 1103 and is allowed to move past the dogs 1103 by virtue of the tapering shape of the dogs 1103. Once the material is beyond the dogs 1103, depending upon what comprises the material, it may have tendency to be somewhat resilient and therefore, decompress and “spring” backwards. The wide portion of the dogs 1103 catches the material and prevents such backward movement.
Dogs 1103 may be triangular, as shown in the figures, or may include a hook shape at the wide portion. Further, dogs may be immovably affixed to the wall of the compaction area 115, or, as shown in
The apparatus may be run with one closed loop hydraulic system that powers the three separate hydraulic actuators described above. Alternatively, each actuator may be a self-contained hydraulic system. Hydraulic system may be charged to between about 1500 psi to about 5000 psi to deliver to the ram 110 about 50 psi to about 400 psi imparted on the waste material. This range is best when large or hard materials are expected to be processed, where breaking or chopping of the material is required. The ram 110 may be operated for municipal solid waste at a minimum of between about 140 to 145 psi, and preferably about 142 psi. Ideally, the ram is preferably configured to deliver up to about a 10-to-1 compression ratio on the waste material. Also, the ram 110 may be a regenerating hydraulic system as is known in the art. The apparatus includes other sensors (not shown) that also provide data to control the process. For example, there may be a sensor to measure the speed of the waste material in the compaction box 115 or in the throat area 119. Data from this sensor, which could be an optical sensor, an IR sensor, an RF sensor, or any other sensor of suitable medium, is received by the control system which is configured with control logic to adjust the speed or number of strokes of the ram 110.
Another way to control the rate of waste feed to the furnace 102 is through analysis of the gases and materials and particulates exhausted from the process. Most gases exhausted from plasma furnace processes include carbon dioxide, nitrogen, carbon monoxide, hydrogen and water. There may also be some particulate matter exhausted with the gas. If there is too much particulate matter, e.g., between about 100 to about 300 ppm, it may be concluded that waste material is being fed too rapidly because not enough of it is reacting. A particulate matter sensor (not shown) may be installed in the exhaust of the furnace that detects the amount of particulates and provides this date to the control system, which is configured with control logic to adjust the speed (cycling of the ram 110) accordingly.
With reference now to
As taught above, it is desirable to maintain a constant feed of the reactor chamber to control the output of the syngas. To this end, other features may be incorporated into the compaction area and the throat area.
Another optional feature is that of a “walking floor” 1711. Two or more floor slats 1713a, b, c are slidably engaged with one another and with rails 1723 mounted to a sub-floor of the compaction box 115. A motor is coupled to the slats and is configured to cause reciprocating movement thereof, in tandem. As one slat moves toward the reactor, the adjacent slat remains in its position until the moving slat stops. The adjacent slat then moves and the cycle is repeated. This alternating iterative movement of the slats serves to urge the contents of the compaction box toward the reactor. A version of the walking floor is described in U.S. Pat. No. 5,560,472 to Gist, issued Oct. 1, 1996, and which is incorporated by reference herein.
Shown in
As described above, control of the hydraulic mechanisms and other functions of the apparatus may be implemented with a computer system (not shown) configured with program logic to cause the computer system to execute the functions required.
The detailed description that follows is presented largely in terms of processes and symbolic representations of operations performed by conventional computers, including computer components. A computer may be any microprocessor or processor (hereinafter referred to as processor) controlled device, such as, by way of example, personal computers, workstations, servers, clients, mini-computers, main-frame computers, laptop computers, a network of one or more computers, mobile computers, portable computers, handheld computers, palm top computers, set top boxes for a TV, interactive televisions, interactive kiosks, personal digital assistants, interactive wireless devices, mobile browsers, or any combination thereof. The computer may possess input devices such as, by way of example, a keyboard, a keypad, a mouse, a microphone, or a touch screen, and output devices such as a computer screen, printer, or a speaker.
The computer may be a uniprocessor or multiprocessor machine. Additionally, the computer includes memory such as a memory storage device or an addressable storage medium. The memory storage device and addressable storage medium may be in forms such as, by way of example, a random access memory (RAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), an electronically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), hard disks, floppy disks, laser disk players, digital video disks, compact disks, video tapes, audio tapes, magnetic recording tracks, electronic networks, and other devices or technologies to transmit or store electronic content such as programs and data.
The computer executes an appropriate operating system such as Linux, Unix, Microsoft® Windows® 95, Microsoft® Windows® 98, Microsoft® Windows® NT, VISTA® Apple® MacOS®, IBM® OS/2®, and later versions thereof. The computer may advantageously be equipped with a network communication device such as a network interface card, a modem, or other network connection device suitable for connecting to one or more networks.
The computer, and the computer memory, may advantageously contain program logic or other substrate configuration representing data and instructions, which cause the computer to operate in a specific and predefined manner as, described herein. The program logic may advantageously be implemented as one or more modules. The modules may advantageously be configured to reside on the computer memory and execute on the one or more processors. The modules include, but are not limited to, software or hardware components that perform certain tasks. Thus, a module may include, by way of example, components, such as, software components, processes, functions, subroutines, procedures, attributes, class components, task components, object-oriented software components, segments of program code, drivers, firmware, micro-code, circuitry, data, and the like.
The program logic conventionally includes the manipulation of data bits by the processor and the maintenance of these bits within data structures resident in one or more of the memory storage devices. Such data structures impose a physical organization upon the collection of data bits stored within computer memory and represent specific electrical or magnetic elements. These symbolic representations are the means used by those skilled in the art to effectively convey teachings and discoveries to others skilled in the art.
The program logic is generally considered to be a sequence of computer-executed steps. These steps generally require manipulations of physical quantities. Usually, although not necessarily, these quantities take the form of electrical, magnetic, or optical signals capable of being stored, transferred, combined, compared, or otherwise manipulated. It is conventional for those skilled in the art to refer to these signals as bits, values, elements, symbols, characters, text, terms, numbers, records, files, or the like. It should be kept in mind, however, that these and some other terms should be associated with appropriate physical quantities for computer operations and that these terms are merely conventional labels applied to physical quantities that exist within and during operation of the computer.
It should be understood that manipulations within the computer are often referred to in terms of adding, comparing, moving, searching, or the like, which are often associated with manual operations performed by a human operator. It is to be understood that no involvement of the human operator may be necessary, or even desirable. The operations described herein are machine operations performed in conjunction with the human operator or user that interacts with the computer or computers.
It should also be understood that the programs, modules, processes, methods, and the like, described herein are but an exemplary implementation and are not related, or limited, to any particular computer, apparatus, or computer language. Rather, various types of general purpose computing machines or devices may be used with programs constructed in accordance with the teachings described herein. Similarly, it may prove advantageous to construct a specialized apparatus to perform the method steps described herein by way of dedicated computer systems with hard-wired logic or programs stored in nonvolatile memory, such as, by way of example, read-only memory (ROM).
As described above and shown in the associated drawings, the present invention comprises an apparatus for conveying solid waste to a furnace. While particular embodiments of the invention have been described, it will be understood, however, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated that any claims issuing in an ensuing patent will cover any and all such modifications that incorporate those features or those improvements that embody the spirit and scope of the present invention.
This application claims priority of U.S. Provisional Application Ser. No. 60/873,748 filed Dec. 8, 2006, and incorporated by reference herein.
Number | Date | Country | |
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60873748 | Dec 2006 | US |