CROSS REFERENCE TO RELATED APPLICATIONS
BACKGROUND OF INVENTION
This application claims priority from U.S. Provisional Application 60/986,284, filed Nov. 7, 2007, which is hereby incorporated by reference.
- SUMMARY OF INVENTION
The present disclosure relates to processes for hydrocarbonaceous feedstocks containing a high percentage of hydrocarbons, such as heavy liquids and solids, which require vaporization and cracking to make diesel fuel and other fuels. These processes are frequently used to process liquids such as used motor oils, and solids such as tires. A problem with these kinds of processes is that the vaporization and cracking of the hydrocarbons results in the formation of carbon on the heat source, which then can interfere with and foul up process equipment. This requires frequent shut-downs and maintenance.
BRIEF DESCRIPTION OF DRAWINGS
A process that avoids the problems due to carbon buildup can be practiced with the use of heating bodies, such as iron balls. Hot iron balls are mixed with hydrocarbonaceous feedstock under non-oxidizing conditions, to vaporize and crack hydrocarbon materials in the feedstock. A buildup of carbon or coke will form on the iron balls during the vaporization and cracking process. To remove the carbon, the heating bodies are then continuously circulated through a heating unit under oxidizing conditions where the balls are passed through a heating fire to burn off carbon. In the heating unit the balls are rolled and exposed directly to a heating fire. The rolling action rubs carbon deposits off the balls and the oxidizing conditions oxidize carbon. After balls are reheated and cleaned of coke, they are recirculated to the mixing chamber through a vapor-lock feeder. Vapors leave the mixer and pass through incoming heated iron balls to further crack vapors as needed to make fuels of a desired viscosity. Nonvaporized feedstock materials are removed from the mixer/vaporizer with iron balls and separated out before or after iron balls circulate through the heater.
FIG. 1 is a schematic diagram of an apparatus viewed from the top.
FIG. 2A is a schematic diagram of a portion of an apparatus as in FIG. 1 viewed from the side.
FIG. 2B is a schematic diagram of an alternate construction to FIG. 2A.
FIG. 3 is a cross-section of a burner.
Reference is made to FIG. 1, which is a schematic view from the top of a system, and FIGS. 2A and 2B, which are each schematics from the side of a portion of exemplary systems for processing used motor oil. With appropriate modification, the system can be used for processing shredded tires, tar sand crudes, oil shale crudes, recycled plastics, or any other feed stock where a major portion is hydrocarbonaceous in nature. The feedstock can also be mixtures of any of these.
Used motor oil is introduced into a mixer 11, through an inlet conduit 13. The motor oil can be introduced into a first end 15, as illustrated in FIG. 2A, or the conduit can extend up through the mixer and be introduced at the mixer second end 17 so that the oil flows counter current to the heated heating bodies 19. Heated heating bodies 19, such as iron balls, are introduced into the first end. The mixer is in the form of a drum with an auger flight 21 (or other transport structure) on the inside will, so that as the drum rotates, the iron balls 19 are moved toward the second end 17 and mixed with the oil.
In FIG. 2A, the heating bodies and the oil move together up through the mixer. In FIG. 2B, at least some of the oil flows counter-current to the heating bodies, with the oil flowing through holes 23 in the auger flight 21.
In both cases, the iron balls mix with the oil and heat the oil to a temperature that will vaporize the hydrocarbon, crack hydrocarbons in the feedstock, and crack volatilized hydrocarbon vapors. Accordingly, the mixer also functions as a vaporizer and cracker. The mixer may also be inclined to carry the balls upward to the heater 25, and thus functions as an elevator. The drum of the mixer is disposed in a containment 27 and has appropriate vapor lock transporters 29 for solid material transfer in and out of the mixer to maintain a non-oxidizing environment.
At the second end of the mixer, the balls and any other nongaseous materials carried up by the flight are withdrawn from the mixer and passed to a heater 25 using a vapor lock system 29 to exclude air from the mixer. In the mixer, some carbon formed upon the balls is removed by the rubbing or abrasive action of the balls in the mixer. The non-gaseous materials withdrawn with the balls includes this carbon, as well as any other solid and non-gaseous materials, such as solid unreacted or partially reacted hydrocarbons in the feedstock and inert materials, which include mineral and metal contaminants. If the feedstock includes shredded tires, such solid materials may include tire cord materials, such as steel and unvolatized polymers.
Referring to FIG. 1 and FIG. 3, which is a cross-sectional schematic, the heater 25 is generally in the form a rotating drum with a system, such as paddles, auger flights, and elevator bars 31 to transport and roll balls 19 along with solid materials through the heater. In the heater carbon on the balls is fractured from the balls by the rolling and moving of the balls due to rotation of the heater. In addition, carbon and other solid materials are combusted as balls are exposed to fire in the heater.
The balls can be exposed and heated by the fire by any suitable system, that may, for example, include elevating and and dropping the balls through the fire. In FIG. 3, the heater 25 includes a burner 33 that extends the length of the heater 25 that directs blue flame directly upon balls being rolled in the heater. A feed pipe 35 for air is also provided that directs oxidizing atmosphere directly on the balls through air conduits 36 to promote oxidation of carbon. In this way carbon that has accumulated in the system is continuously removed. The oxidizing carbon also functions as a fuel in the heater.
The heater also functions to heat the iron balls to a high temperature. When these heated iron balls are introduced into the mixer, they must be hot enough to sufficiently heat the feedstock to vaporization and cracking temperatures in the mixer.
After leaving the heater any remaining solid materials are separated from the balls, and the balls are recycled back through a vapor-lock transport to the mixer. The separation may be by any suitable technique, such as screening. Effluent combustion gasses from the heater are directed to a stack 45 or other suitable structure.
The vapor-lock transport inlet 29 to mixer can also function as a cracker, as particularly shown in FIG. 2A and FIG. 2B. In FIG. 2A, the hot iron balls fall through vapors leaving the mixer, which further heats and cracks the vapors. A spreader 37 can be used to mix the heating bodies and increase the gas permeability for vapor flow. In FIG. 2B, screens or ramps 39 with holes 41 (to allow passage of vapors) cause the balls to roll through the vapors.
The heating bodies are transported from the vapor lock transport 29 back into the mixer, to again be transported through the mixer.
The vapors from the vapor lock transport are passed to a condenser 41, where condensible liquid hydrocarbons are produced for fuels and as hydrocarbon feedstocks. The non-condensible vapors from the condenser are recycled back to the heater, where they are used as fuel for the heater.
Optionally heat from condensing the vapors can be used to pretreat the feedstock to remove both condensible vapors and water in the feedstock before it is heated and cracked in the mixer. These vapors can be passed to the burner of the heater. A counter-flow heat exchanger using hot vapors to heat the feed stock can be used in this function, where it acts as a vapor condenser-feedstock heater.
The heating bodies may be any suitable material that can be heated and transfer heat in the process, and is tough enough to withstand the tumbling in mixer and heater. In addition, denser materials are preferred to help with the removing of the carbon effect in the heater. Balls of iron, or an iron alloy, have been found suitable. Reference to “iron balls” or “balls” in this disclosure refers generally to heating bodies of any suitable material.
While this invention has been described with reference to certain specific embodiments and examples, it will be recognized by those skilled in the art that many variations are possible without departing from the scope and spirit of this invention, and that the invention, as described by the claims, is intended to cover all changes and modifications of the invention which do not depart from the spirit of the invention.