Distillation: apparatus – Apparatus – Systems
Reexamination Certificate
1999-08-24
2001-06-05
Yildirim, Bekir L. (Department: 1764)
Distillation: apparatus
Apparatus
Systems
C202S127000, C196S117000, C122S174000, C122S235140, C122S236000, C122S356000
Reexamination Certificate
active
06241855
ABSTRACT:
REFERENCE TO PENDING APPLICATIONS
This application is not related to any pending applications.
REFERENCE TO MICROFICHE APPENDIX
This application is not referenced in any microfiche appendix.
TECHNICAL FIELD OF THE INVENTION
In general, the present invention is directed to crude oil refining. In particular, the present invention is directed to a process and article of manufacture to advance the efficiency of severe thermal cracking, or delayed coking, by introducing coker feedstock to the lower portion of a delayed coker charge heater's radiant heating section and “upflowing” such feedstock to an exiting capability located in the generally upper portion of said heater's radiant heating section.
BACKGROUND OF THE INVENTION
The present invention can be best understood and appreciated by undertaking a brief review of the crude oil distillation process, and most particularly, the role delayed coking plays within that process.
In its unrefined state, crude oil is of little use. In essence, crude oil (a.k.a. hydrocarbon) is a complex chemical compound consisting of numerous elements and can. Such impurities can include, but are not limited to sulfur, oxygen, nitrogen and various metals that must be removed during the refining process.
Refining is the separation and reformation of a complex chemical compound into desired hydrocarbon products. Such product separation is possible as each of the hundreds of hydrocarbons comprising crude oil possess an individual boiling point. During refining, or distillation, crude oil feedstock temperature is raised to a point where boiling begins (a.k.a. “initial boiling point, or “IBP”) and continues as the temperature is increased. As the boiling temperature increases, the butane and lighter fraction of crude oil are first distilled. Such distillation begins at IBP and terminates slightly below 100° F. The fractions boiling through this range are represented and referred to as the “butanes and lighter cut.”
The next fraction, or cut, begins slightly under 100° F. and terminates at approximately 220° F. This fraction is represented and referred to as straight run gasoline. Then, beginning at 220° F. and continuing to about 320° F. the Naphtha cut occurs, and is followed by the kerosene and gas/oil cuts, occurring between 320° F. and 400° F., and 450° F. to 800° F., respectfully. A term-of-art “residue cut” includes everything boiling above 800° F.
The residue cut possesses comparatively large volumes of heavy materials and two fundamental processes are employed to convert appreciable amounts of such residuals to lighter materials—thermal cracking and delayed coking. While thermal-cracking may be properly considered “the use of heat to split heavy hydrocarbon into its lighter constituent components,” delayed coking should be considered “severe thermal cracking” and occurs within a coke drum after a coker feedstock has been heated in an apparatus referred to as a coking heater, or “delayed coker charge heater.” An improved delayed coker charge heater and process serve as the focus of the instant invention.
Delayed coking processes and heaters are well known in the art and have been discussed and disclosed, for example, in U.S. Pat. No. 5,078,857, invented by M. Shannon Melton and issued Jan. 7, 1992 (hereafter referred to as “Melton”). Melton and prior art references cited herein are hereby provided to disclose and distinguish said art from the novel improvements embodied and afforded by the instant invention.
Today, delayed coker charge heaters are required to address service demands far more severe than in times past. Such demands typically include reduced recycling rates, heavier processing fluids (a.k.a. “coker feedstock”), and increases in undesirable processing fluid components, such as, but not limited to, asphaltine content, inerts, metals, salts, etc. Increased fresh feed charge rates and the afore stated demands result in a commensurate increase in fouling/coking rates within the interior portions of a coker heater's processing coil or heating conduit. Increased fouling rates, in turn, increase occurrences of coker “down time” to decoke fouled processing coils. Coker charge heaters as represented within the present art have failed to adequately address the afore stated problems. The present invention, by disclosing a novel and unique processing design and methodology, addresses such increased service demands and obviates many of the deficiencies represented in the present art.
Accordingly, the present invention is directed to an improved process and article of manufacture to advance the performance efficiency and life cycle of delayed coker charge heaters by introducing coker feedstock to the lower portion of a delayed coker charge heater and “upflowing” such feedstock to an exiting capability located in the generally upper portion of said coker charge heater's radiant heating section.
BRIEF SUMMARY OF THE INVENTION
The present invention provides for an improved method and article of manufacture for greatly improving upon coker charge heater performance and component longevity by introducing coker feedstock to the lower portion of a delayed coker charge heater and “upflowing” such feedstock through a heating conduit (a.k.a. “process coil”) to an exiting outlet located in the generally upper portion of said coker charge heater's radiant heating section.
The “upflowing” of a coker charge heater's process fluid permits enhanced stripping and shredding of fluid film from the interior portion of the coker's heating conduit wall, and mixes such film with the process fluid. This enhanced mixing cools the resultant fluid film, increases interior heat transfer rates, cools process coil tube metals and reduces coking/fouling rates within the interior portion of the process coil. These benefits result directly from lower pressures, enhanced vaporization and mixing introduced to delayed coker processing by way of upflowing coker feedstock through a process coil located in the coker's radiant heating section.
Consequently, it is an objective of the instant invention to reduce delayed coker charge heater outlet pressure, thereby providing for an associated reduction in the fouling rate of the interior portion of a delayed coker heater's process coil, or heating conduit.
It is another objective of the instant invention to migrate the hottest part of the process coil, and least able to accommodate elevated radiant flux rates, to the generally upper portion of a delayed coker charge heater's radiant heat section.
It is a further objective of the instant invention to cause enhanced shredding of feedstock film from the interior of the heating conduit wall and mix such film with the process fluid resulting in a cooler fluid film, an increase in interior heat transfer rates, and cooler process coil tube metals. Such effects further reducing coking/fouling rates within the interior portion of the process coil.
Other objects and further scope of the applicability of the present invention will become apparent from the detailed description to follow, taken in conjunction with the accompanying drawings wherein like parts are designated by like reference numerals.
REFERENCES:
patent: 4002149 (1977-01-01), Yamamoto et al.
patent: 5078857 (1992-01-01), Melton
patent: 5284438 (1994-02-01), McGill et al.
patent: 5656150 (1997-08-01), Reed et al.
patent: 6095097 (2000-08-01), Gibson et al.
Eischen James T.
Gibson Robert L.
Gibson William C.
Head Johnson and Kachigian
Petro-Chem Development Co. Inc.
Yildirim Bekir L.
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