Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including means rotating reaction chamber during use
Reexamination Certificate
1997-10-23
2001-03-20
Beck, Shrive (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including means rotating reaction chamber during use
C422S204000, C422S201000, C422S202000, C422S233000, C196S112000
Reexamination Certificate
active
06203765
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for removing contaminants from used oil by subjecting the oil to vaporization and pyrolysis, whereby coke is formed. The contaminants remain with the coke, which can be separated from the oil. The invention further relates to a rotating, indirectly heated retort or reactor in which the process is practised.
BACKGROUND OF THE INVENTION
Processes are known for reclaiming oil from contaminated used oil (sometimes referred to as waste oil).
One such process is disclosed in U.S. Pat. No. 5,271,808, issued Dec. 21, 1993 to Shurtleff. Shurtleff discloses a process wherein an inclined boiler heats the waste oil, vaporizing and driving off lighter hydrocarbons at temperatures of about 650° F. Heavier hydrocarbons and contaminants, amounting to about 10% of the original oil, collect as a sludge in the bottom of the boiler. The sludge drains for disposal. The lighter hydrocarbons are condensed as a reclaimed oil product.
However, Shurtleff's process produces an oily waste which itself requires specialized disposal.
Other methods which can produce a reclaimed oil and an oil-dry contaminant typically involve subjecting the waste oil to thermal pyrolysis.
For example, in U.S. Pat. No. 5,423,891, issued to Taylor, a process is disclosed for the gasification of solids waste. Heat carrier solids (HCS) are first heated and then fed co-currently with hydrocarbon-bearing solids waste through a rotary kiln retort. The solids waste and HCS co-mingle, transferring heat. The resulting temperatures of 1200 to 1500° F. are suitable to thermally pyrolyze the hydrocarbons in the waste. The resultant vapours are extracted for condensation. The retort solids and HCS are discharged from the kiln for recovery of the retort solids and re-heating of the HCS.
In Taylor's system the HCS are continuously circulated in a material handling loop. The HCS is a coarse granular solid which is heated outside the kiln and gives up its heat inside the kiln. Transport of the HCS around the loop involves considerable materials-handling equipment.
In U.S. Pat. No. 4,473,464, issued to Boyer et al., a process is disclosed for treating heavy crude oil. Carbonaceous solids are finely ground for concurrent feed with crude oil to an indirectly heated kiln. Pyrolyzed hydrocarbon vapours are condensed. Coke and carbonaceous solids are screened, ground and recycled outside the kiln. Heat loss to the solids is minimized and the crude oil is preheated to a temperature high enough to balance any temperature loss by the solids.
U.S. Pat. No. 4,303,477, issued to Schmidt et al., discloses co-currently adding a consumable fine-grained reactive solid to a waste material for binding metal and sulfur contaminants during treatment. The reactive solids, such as lime having a grain size typically less than 1 mm, and waste are thermally cracked as they progress through a rotating, indirectly fired kiln. The solids make a single pass through the kiln, the reactive solid being consumed in the process.
Some of the above described prior art processes involve significant material handling challenges in the recycling and conveyancing of large masses of hot, coarse solids. Other processes, which do not recycle hot solids, involve rejection of a portion of the oily waste or irreversibly consume a catalyst.
There is therefore a need for a simplified process for separating contaminants from used oils. It is the objective of the present invention to provide such a process.
SUMMARY OF THE INVENTION
The present invention provides a simple apparatus and process for reclaiming oil from used, contaminated oil feed. In general, the process comprises feeding used oil through a feed line to a rotating thermal reactor vessel wherein the oil is pyrolyzed to produce hydrocarbon vapour and coke. The contaminants become associated with the coke. The vapour and coked solids are separately removed from the vessel. The vapour is condensed to produce a substantially contaminant-free oil product and the contaminant-rich, dry coked solids are collected for disposal, possibly as feed for a cement kiln.
The equipment used includes a reactor comprising a rotating vessel housed in a heating chamber, means for feeding used oil into the rotating vessel, and an oil recovery system comprising a vapour extraction pipe, a solids removal cyclone, and vapour condensation equipment.
More particularly, the rotating vessel comprises a cylindrical side wall and end walls forming a single internal reaction chamber. Structural cylinders extend from the end walls along the vessel's longitudinal axis. The diameter of the end cylinders is small relative to that of the cylindrical side wall. A stationary external housing surrounds the vessel and combines therewith to form an annular heating chamber. The external housing is sealed to the end cylinders by rotary seals. A burner extends into the heating chamber. The rotating vessel is indirectly heated so that its internal surfaces are sufficiently hot to vaporize and pyrolyze the feed oil. The feed oil is introduced into the reaction chamber wherein it vaporizes and pyrolyzes, forming hydrocarbon vapour and coke. Metals and other contaminants become associated with the coke. A bed of non-ablating, granular coarse solids is provided within the reaction chamber. As the vessel rotates, the coarse solids scour the vessel's internal surface and comminute the coke into fine solids. The fine solids may include solids introduced with the feed oil. The vapour is extracted from the reaction chamber through an axial pipe extending through an end cylinder. The fine solids are separated within the reaction chamber from the coarse solids for removal from the vessel, preferably using a spiral chute. The chute spirals from a screened entrance at the vessel's circumference to a discharge outlet at the vessel's axis. The chute's screen excludes coarse solids and collects only the fine solids. The fine solids are conveyed out of the vessel through an end cylinder for disposal. Fine solids may also be elutriated with the vapours. Any fine solids associated with the vapours are separated out by processing in external means, such as a cyclone. The substantially solids-free vapours are then condensed to yield product oil. The contaminant-rich fine solids are collected for disposal.
Only a small portion of the feed oil is converted to coke, the remainder being recovered as a substantially contaminant-free product oil.
REFERENCES:
patent: 3630501 (1971-12-01), Shabaker
patent: 3655518 (1972-04-01), Schmalfeld et al.
patent: 4303477 (1981-12-01), Schmidt et al.
patent: 4439209 (1984-03-01), Wilwerding et al.
patent: 4473464 (1984-09-01), Boyer et al.
patent: 5423891 (1995-06-01), Taylor
patent: 1334129 (1995-01-01), None
Odut Steve
Taciuk Gordon
Taciuk William
Wheeler Charlie
Alberta Oil Sands Technology & Research Authority
Beck Shrive
Doroshenk Alexa A.
Millen White Zelano & Branigan P.C.
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