Abstract:
A method of burning tires in a horizontally rotating combuster includes the steps of loading the tires into a rotating combustion chamber through a traveling air lock and burning them until they are reduced to ash; enhancing combustion by tumbling the burning tires in a tapered rotating chamber while adding preheated draft air; controlling the intake draft air using thermal expansion of the rotary combustion chamber to activate the draft control valve; advancing the residual ash with each successive revolution of the combustion chamber by use of angled flights on the inner surface of the chamber to an afterburner for completion of the combustion and disposal of the ash.

Description:
This application is a division of application Ser. No. 08/966,135, filed Nov. 7, 1997, now U.S. Pat. No. 5,967,062. Priority is claimed for this application under 35 USC 119(e) based on provisional application Ser. No. 60/031,320, filed Nov. 19, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present apparatus relates to the disposal of tires through combustion. It has been shown that tire combustion is possible by using stationary incinerators. In such devices, tires are not mixed as they burn and the solid by-products of combustion are gathered in collection ducts. In contrast, the present apparatus differs from previous methods of tire combustion in that the entire combuster rotates. Tires are tumbled and retained in the primary burn zone for as long as possible. After tires have been reduced to ash, solid waste is forwarded to the exhaust area using a series of baffles, I.e. flights. Once the hot gases and solid debris have left the exhaust area, they enter the afterburner, where complete burning of the remaining volitiles is performed using a secondary enrichment of oxygen. 
     2. Prior Art 
     The U.S. Pat. No. 3,946,680; U.S. Pat. No. 4,565,138; U.S. Pat. No. 4,551,051; U.S. Pat. No. 4,895,083; and U.S. Pat. No. 4,180,004 disclose various apparatuses used for combustion of tires. This apparatus; however, differs from previous efforts at tire combustion in several ways. 
     U.S. Pat. No. 4,551,051 and U.S. Pat. No. 4,565,138, illustrate an inclined ramp and a ram, respectively, for loading tires into the primary burn zone, U.S. Pat. No. 4,180,004 teaches the step of shredding the tires before delivery to the combuster. 
     U.S. Pat. No. 4,895,083; U.S. Pat. No. 4,565,138; and U.S. Pat. No. 3,946,680, burn the tires as a resting pile. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to provide a means for disposing of tires by combustion using a rotating burn chamber. 
     A principle objective of this invention is to provide a means for removing the solid by-products of the tire combustion from the primary burn area by using a series of inclined baffles, resembling the threads of an internal lead screw, which carry the debris toward the exit of the combuster at a rate slow enough to allow thorough combustion. 
     Another important objective of this invention is to provide a method for loading the tires into the combuster using an airlock with an automated lid. 
     Another important objective of this invention is to provide a method for loading tires into the combuster using a sealed airlock which reduces the ingress of air and the egress of the volatile gases through the loading opening and places the tires into the combuster in a controlled manner. 
     Another important objective of this invention is to provide a method for burning tires based on a rotating combuster that tumbles the tires as they burn to ensure thorough and rapid combustion. 
     Another important objective of this invention is to provide a means of enhancing tire combustion using a preheated draft. 
     Another important objective of this invention is to provide a means for controlling the intake draft using the thermal expansion of the rotary combustion chamber to activate a draft control valve. 
     Another important objective of this invention is to provide shielded draft entry to prevent debris from back flowing into the draft air ducts. 
     Another important objective of this invention is to provide a means for preventing tire refuse from leaving the burn area prematurely by using a ramp in the rotary combustion chamber. 
     Other important objectives of this invention include preheating the draft air to promote rapid combustion in the primary burn zone and the use of a tire fueled afterburner to eliminate remaining volatiles escaping from the primary burn zone. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric drawing of the tire injector airlock; 
     FIG. 2 is a cross sectional view of the rotary combustion chamber as viewed from the side; and 
     FIG. 3 is a cross sectional view of the rotary combustion chamber including the afterburner as viewed from the side. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Overview 
     The combustion process utilizes two main chambers; the rotary combustion chamber and the secondary combustion chamber. First, tires are loaded into the rotary combustion chamber by means of an automated airlock. Once inside, the tires or fuel is exposed to a preheated draft that provides oxygen-rich air to the primary burn zone. After the tires have been reduced to ash and hot gases, the by-products are forwarded into the secondary combustion chamber or afterburner. Within the afterburner, solid waste is removed from the airstream and remaining volatiles are eliminated using a secondary enrichment of oxygen. 
     The tires  41  are loaded into the rotary combustion chamber by means of a tire injecting airlock, shown in FIG. 1. A sliding carriage  1  is used to transport tires into the rotary combustion chamber one at a time. As shown in FIG. 1, the sliding carriage  1  is formed as a bottomless_rectangular box with a forward wall  28 , side walls  29  and  30  and a rear wall  31 . As shown in FIG. 1, the forward wall  28  forms the portion of the airlock between the interior of the combustion chamber and the outside environment. FIG. 1 shows an automated lid  2  on the carriage which has been designed to open and close automatically at the appropriate time during the tire loading process. The lid  2  is connected to the sliding carriage  1  by a hinge  36 _extending between the side walls  29  and  30 . In order to open the lid, for example, a pneumatic cylinder  3  is employed. The cylinder applies force on a lever arm  5 , mounted below the lid, by means of a mechanical assembly  4  which extends through the rear wall  31 . This arrangement allows the cylinder to hold the lid open because the force acting on the lever arm  5  has enough leverage and magnitude to hold the lid in position. 
     The sliding carriage  1  is movably mounted in a channel shaped ramp  16 . The ramp  16  is mounted on the wall  32  which closes the front end of the combustion chamber. The ramp  16  surrounds the loading aperture  33 , shown in FIG.  3 . The ramp  16  has a planar surface  17  of which a portion, shown encompassed by the walls of the sliding carriage in FIG. 1, forms the bottom of the airlock. Wheels  6  are mounted on the upstanding sidewalls  18  of the ramp  16 . 
     Once the tire has been loaded, the lid  2  is closed by reversing the force from the pneumatic cylinder  3 . This action applies less force at the lever arm  5  and causes the lid to rotate about its hinge  36  to a closed position. Consequently, the movements of the mechanical assembly  4  operated by the pneumatic cylinder play a major role in automating the lid of the carriage. 
     In addition to controlling the carriage lid  2 , the pneumatic cylinder  3  is also used to inject tires into the rotary combustion chamber. Once a tire has been loaded into the carriage, initial extension of the pneumatic cylinder&#39;s piston seals the tire in the carriage by automatically closing the lid  2  by movement of the mechanical assembly  4  toward the forward wall  28  of the carriage. Further extension of the piston and mechanical assembly  4  brings the sloped forward surface  40  of the lever arm into contact with the forward wall  28  of the carriage thereby rolling the sealed carriage  1  across a series of wheels  6  and into the rotary combustion chamber shown in FIG.  2 . Once inside, the carriage frame  1  is supported by its track  15  over a bottomless region opening directly into the primary burn zone  7 . Because the sealed carriage is bottomless, the carriage will empty before the rear wall  31  is extended into the rotary burn chamber thereby maintaining the separation between the interior of the burn chamber and the outside environment. The tire drops into the rotary combustion chamber and the piston of the pneumatic cylinder  3  is subsequently reversed withdrawing the empty carriage onto the ramp  16 . 
     Reversing the piston of the pneumatic cylinder  3  causes the carriage frame  1  to retreat in a linear manner until the motion is stopped by a cushion cylinder (not shown). After the frame  1  has been returned to its original position, further retraction of the assembly  4  by the pneumatic cylinder  3  applies enough force on the lever arm  5  to cause the lid  2  to open, ready for the next tire to be added. 
     Collectively, regions or zones  7 ,  8 , and  9  comprise the rotary combustion chamber. Essentially, it is a tube of varying diameters across its longitudinal axis which may be constructed of one or several sections. The purpose of the rotary combustion chamber is to provide a means for burning tires and removing the waste generated from combustion. This is accomplished by rotating the combuster on powered rollers  10  and tumbling the burning debris across a series of inclined baffles  11  positioned along the inner wall of the rotary combustion chamber. 
     As the rotary combustion chamber rotates, provisions are made to support it under longitudinal and radial thermal expansion. The rotary combustion chamber is supported at positions A, B, and C by powered rollers  10 . Radial thermal expansion is addressed by using bearings  12  that are sized to fit the rotary combustion chamber at the running temperature. Longitudinal thermal expansion is limited at position A such that the rotary combustion chamber can expand only towards its narrow end. The uniaxial thermal expansion is used in conjunction with mechanical duct valves  13  to control the draft balance in the rotating chamber. 
     The primary burn zone  7  accelerates tire combustion by tumbling the tires within the burn chamber and exposing them to oxygen-rich, preheated draft air. Heat is recovered from the combustion process by draft air passing through the draft passage  19  between the outer layer  21 _and the inner layer  22  of the rotary combustion chamber wall and returned to the primary burn zone  7  at shielded draft entrances  14 . The shields covering the draft entrances are aligned so as not to allow debris to backflow into the air ducts and they protrude into the burn zone far enough to help tumble the tires as the rotary combustion chamber rotates. Tumbling the tires and using preheated draft air ensures that all burnable materials undergo accelerated combustion in the primary burn zone. 
     The reduced tire conveyer zone  8  continuously removes solid waste from the primary burn zone  7  and prevents unburned tires from advancing prematurely in the combuster. The slope of the tube in this region of the combuster serves as a means for fuel retention; unburned tires fall backwards into the primary burn zone  7  until they are reduced to small pieces, and ash. These small pieces are then carried by flights or baffles  11 , resembling the threads of an internal lead screw, toward the exhaust zone  9  at a rate slow enough to allow completion of the tire-reduction process. The flights  11  continuously lift solid material from the bottom of the combuster, then drop it so that it falls through the hot gases. Turning the material with the flights enhances combustion by ensuring good temperature uniformity. Consequently, the slope of the reduced tire conveyor zone provides maximum fuel retention, and the flights  11  along the inner wall promote continuous waste removal and uniform tire combustion. 
     The exhaust tube zone  9  routes the burned debris and hot gases to an afterburner  20 , shown in FIG. 3, and provides a means for controlling the draft balance in the rotating chamber. The end of the tube protrudes slightly into the afterburner so that ash drops to the bottom, while hot gases continue upwards through the afterburner, to a boiler or some other device downstream. 
     Draft balance control is accomplished using the thermal expansion of the unit to activate a draft control valve  13 . The draft control valve  13  has a flap valve  23  mounted on outer layer  21  of the rotary combustion chamber. The position of the flap valve  23  is controlled by an elongated actuator  24  and biasing device  35 . The actuator is pivotally mounted on outer layer  21 . One end of the actuator  24  is connected to the flap valve  23  and the other end is connected at  26  to the inner layer  22  by wires or rods  25 . When the system is running cool, thermal cooling will cause the duct switch  13  to direct draft air straight to the primary burn zone  7 , as_shown in FIG.  2 . Entering draft air will in turn increase combustion in the primary burn zone and return the system to higher temperatures. In contrast, when the system is running hot, longitudinal thermal expansion causes inner layer  22  to elongate moving  26  longitudinally to pivot actuator  24  opening flap valve  23  to direct oxygen-rich draft air away from the primary burn zone  7  and into the afterburner. The oxygen-rich draft air enters the afterburner through opening  42  and mixes with the hot gases within the afterburner, causing complete combustion of any remaining volatiles, while the ash drops to the bottom of the afterburner for removal and processing. 
     The purpose of the afterburner is to eliminate remaining volatiles from the reduced tires and to remove ash from the flow of hot gases. In order to enhance the secondary combustion process, the reduced tires are exposed to a secondary enrichment of oxygen in the secondary combustion chamber  39 . Any remaining ash is thrown against the inner wall of the afterburner, whereupon the ash slides along the wall toward the bottom of the afterburner for collection and removal. 
     In order to bring the afterburner to operating temperature in a timely manner, the afterburner has been equipped with a semi-isolated preheat chamber  38  separated from the secondary combustion chamber  39  by a partition  37  though which heat is transferred. Oil burners  34  within the chamber have the ability to supplement energy requirements in the absence of tire fuel. Most of the time, however; the preheat burners will not be running, as the heat energy from the tire fuel will be enough to eliminate remaining volatiles once the secondary enrichment of oxygen is applied. Once the tires have completed the combustion process, the ash is removed from the afterburner from the base of the structure after having passed through partition  37  and the hot gases are forwarded to a boiler or some other device downstream. 
     The rotary tire combuster provides a means to improve the combustion of passenger and highway truck tires. The intake draft is preheated, the tires are tumbled, and the apparatus is supported in ways which work cohesively to enhance the combustion process. 
     The supports, for example, allow longitudinal thermal expansion of the apparatus as the unit changes temperature. As a result, changes in the length of the combuster reposition a draft control valve attached to the rotary combustion chamber. This valve, in turn, directs air toward the primary burn zone, forming a preheated draft, or towards the afterburner, providing a secondary enrichment of oxygen. In either case, oxygen rich air is automatically directed to different regions of the apparatus in order to control the temperature and to use the draft air as efficiently as possible. 
     Tires are loaded using an automated airlock that is designed to minimize smoke and energy losses at the entrance. Once inside the rotary combustion chamber, the tires are retained in the primary burn zone until reduced to ash and hot gases. Continual rotation of the combuster tumbles the debris across a series of internally mounted baffles that lift the ash from the bottom of the pile and advance it towards the exhaust end of the tube. Once past the exhaust, any remaining volatiles are eliminated in an afterburner using secondary enrichment of oxygen. In addition to separating the ash from the fuel, the baffles, or flights, turn the debris in order to ensure good temperature uniformity. 
     Consequently, the rotating combuster is an improvement in the field of tire combustion. It tumbles the burning mixture and channels draft air in ways which enhance the combustion process. Although a conveyor belt is not used in the primary burn zone, as in other conbusters, its streamlined design and other qualities make it a viable apparatus for the production of tire derived fuel. 
     In a general manner, while there has been disclosed an effective embodiment of the invention, it should be well understood that the invention is not limited to such an embodiment as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention embodied in the claims.