Furnaces – Fuel feeders – Chute
Reexamination Certificate
1999-11-23
2001-05-22
Gravini, Stephen (Department: 3749)
Furnaces
Fuel feeders
Chute
C110S185000, C110S186000, C110S246000, C110S255000, C110S267000, C110S1010CD, C414S208000, C414S149000, C414S152000
Reexamination Certificate
active
06234091
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to using tires as a source of supplemental fuel to heat a rotating kiln, and more particularly to a feed chute apparatus for injecting tires and other combustible materials into the kiln.
2. Description of the Background Art
Rotating kilns are frequently used in the production of cement. Because such kilns operate at extremely high temperatures, it is possible to burn various forms of liquid and solid combustible waste materials as a source of supplemental heat. At the high temperatures found in such kilns, which are on the order of 3400 degrees F. and above, the waste materials tend to combust fairly completely while producing little or no undesirable gaseous or solid emissions. Therefore, these waste materials can serve as a supplemental fuel, thereby reducing the demand for and cost of the primary fuel.
One form of waste that is burned in cement kilns is rubber tires from automobiles and trucks. Rubber tires make a very good source of supplemental fuel for a rotary kiln because they burn at comparatively hot temperatures. The extremely high temperatures within a cement kiln will cause the rubber tires to burn without any significant liquid, solid or gaseous waste byproducts which might otherwise be detrimental to the environment. Accordingly, the burning of tires in rotary kilns helps alleviate the growing problem of tire disposal without significantly impairing the environment.
Conventional feed systems used for injecting tires into a cement kiln have typically suffered from several deficiencies. For example, some feed systems require that the tires be shredded and then packaged into “fuel packages” of a specific size to accommodate the dimensions of the feed system. However, such processing of used tires increases the overall cost of tire disposal, increases the cost of operating the kiln, as well as requires the use of special equipment and additional manpower to cut the tires and package the resulting pieces into suitably sized packages. Therefore, it is more efficient and cost effective to inject whole tires into the kiln.
One known method of tire injection into the kiln uses gravity to drop a tire into an opening in the kiln wall from a loading area as the kiln rotates. The loading area may be positioned vertically or rotates with the kiln and gravity causes the tire or other fuel item to slide into the interior area of the kiln when the loading area becomes disposed substantially vertically. A drawback of that type of system, however, is that the tire is dropped from the top of the kiln into highly fluidized material causing the material to splash and thereby creating excessive turbulence and inconsistent combustion within the kiln. To address that problem, feed systems have been developed that will positively inject the tire into the kiln during a portion of the rotational travel of the kiln without relying on gravity to do so.
For example, one known injection system comprises an entrance chute having an outer end portion protruding outwardly from a wall of the kiln and an inner end portion which protrudes into the kiln. The entrance chute further is disposed such that it is positioned tangentially to the kiln wall. The entrance chute includes a gate assembly having a cam follower assembly and a pivotally mounted gate member. The cam follower assembly causes the gate member to be urged pivotally between open and closed positions in response to movement of the cam follower assembly over a cylindrical camming wall positioned at a predetermined location relative to the kiln. When the cam follower assembly has caused the gate member to open, a plurality of tires or other items forming a source of supplemental fuel are positively propelled into the entrance chute by one or more external tire injecting apparatuses synchronized in operation to rotation of the kiln. A dam formed at the inner end portion of the entrance chute prevents highly fluidized material within the kiln from flowing up into the entrance chute and further forms a channel relatively free of the fluidized material into which the tires may be injected during a predetermined portion, or portions, of rotational travel of the kiln.
However, even the positive injection system described above has drawbacks, namely complexity and cost. Therefore, a need still exits for an efficient, low cost feed system for injecting tires into a rotating kiln. The gravity feed system of the present invention satisfies that need, while overcoming deficiencies found in conventional feed systems.
BRIEF SUMMARY OF THE INVENTION
The present invention is an apparatus for feeding tires and other combustible materials by gravity into a rotating kiln as a source of supplemental heat. By way of example, and not of limitation, the apparatus comprises a feed ramp that is supported by a housing having side walls and a hinged lid. A gate mechanism is positioned below the feed ramp and includes an arm assembly pivotally coupled to the sides of the housing. The arm assembly includes at least one arm with a perpendicular post at one end that blocks the end of the feed ramp in a rest position but provides a clear path when the gate mechanism pivots away from the feed ramp. A gate operator is attached to the arm assembly to impart pivotal motion upon activation. A support frame is provided to position the apparatus adjacent to a rotating kiln at a height and orientation suitable for gravity feeding of material into the kiln. Preferably, the support frame includes a staging platform on which tires and other combustible materials can be stored and then placed onto the feed ramp for delivery into the kiln.
To ensure that tires and other materials will be gravity fed into the kiln, the apparatus is oriented on the support frame such that the plane of the feed ramp has an angle of inclination between approximately 33 degrees and approximately 60 degrees, and preferably 47 degrees. To facilitate proper alignment of the apparatus with the feed opening in the kiln before releasing the tires, a sensor is used to determine the position of the feed opening relative to the feed ramp.
In operation, tires or other combustible materials are placed on the feed ramp. As the kiln rotates, the feed opening eventually comes into alignment with the feed ramp. At that point, the sensor detects this position and sends a control signal to the gate operator. The gate operator causes the arm assembly to pivot away from the feed ramp and to retract the posts. The tire or other combustible material then slides down the feed ramp and into the kiln since the angle of inclination is sufficient to allow the material to be gravity fed out of the end of the feed chute.
An object of the invention is to inject whole tires into the interior area of a rotating kiln.
Another object of the invention is to provide a tire injection system for a rotating kiln that relies solely on gravity feed.
Another object of the invention is to provide a gravity feed tire injection system that injects a whole tire into a rotary kiln at a position that is offset from vertical.
Another object of the invention is to provide a gravity feed tire injection system that is automatically controlled to inject a tire when the opening to the kiln is at a specified position around the periphery of the kiln.
Another object of the invention is to introduce a stream of tires into a rotating kiln without creating a bottleneck.
Another object of the invention is to provide a feed chute apparatus for a rotating kiln that feeds tires into the kiln at a desired rate.
Another object of the invention is to provide a feed chute apparatus for injecting tires into a cement kiln which eliminates the need to cut up or otherwise package the tires for injection.
Further objects and advantages of the invention will be brought out in the following portions of the s
Gravini Stephen
O'Banion John P.
Rinehart K. B.
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