US3130146A - Production of coke - Google Patents

Description

April 21, 1954 w. E. PLASTER 3,130,146

PRODUCTION OF COKE Filed April 24, 1961 PRODUCT SEPARATION FUEL GAS AIR QUENCH 16 INVENTOR.

w. E. PLASTER WM M ATTORNEY$ United States Patent Ofilice 3,139,146 Patented Apr. 21, 1964 3,130,146 PRGDUCTIGN 8F CQKE William E. iiaster, Eartiesville, Okla, assign-or to Phillips Petroleum Company, a corporation of Delaware Filed Apr. 24, 1961, Ser. No. 105,058 16 Claims. (Cl. 2tl8lii6) This invention relates to a process and apparatus for producing coke. In one of its aspects, this invention relates to process and apparatus for treating a high-sulfur crude oil. In another aspect, this invention relates to process and apparatus for treating petroleum residues to obtain from them a high quality coke. In another aspect, this invention relates to process and apparatus for desulfurizing and coking a petroleum residuum. In still another aspect, this invention relates to process and apparatus for producing metallurgical-grade coke. In yet another aspect, this invention relates to a process and apparatus for coking petroleum residue which comprises spraying the residue downwardly into a vertically elonganted coking zone, introducing into a lower portion of the zone a hot reducing gas, passing the hot reducing gas upwardly in countercurrent contact with the descending residue while, in one embodiment, maintaining an external portion of the zone at a constant temperature by indirect heat exchange in another embodiment, removing the resulting coke from a lower portion of the zone as a product of the process; and, in another embodiment, removing the resulting gas from an upper portion of the zone as a product of the process.

Processes and apparatus used heretofore in the cracking of petroleum residues, and especially residues from highsulfur sources such as Monagas Crude, have been directed primarily to production of light liquid products such as motor fuel, diesel fuel, etc. Coke produced in such a process has been considered a necessary evil and has either been consumed as fuel in the process or discarded; in general, it has not possessed the desirable properties of physical strength, high activity, high carbon concentration, and low impurities, especially sulfur, of metallurgical coke. Also, heretofore a single piece of equipment, in the form of a furnace of cheap construction, has not been available for carrying out the entire coking operation.

It is an object of this invention to provide process and apparatus for coking petroleum. It is another object of this invention to provide process and apparatus for producing metallurgical-grade coke. It is another object of this invention to provide process and apparatus for continuously coking a petroleum residue. It is still another object of this invention to provide a low cost process and apparatus for producing liquid fuels and metallurgical-grade coke from high-sulfur petroleum residue.

Other aspects, objects and advantages will be apparent upon examination of the disclosure, drawing and appended claims.

According to my invention, there are provided a process and apparatus for coking petroleum residue which comprises spraying said residue downwardly into a vertically elongated coking zone, introducing into a lower portion of said zone a hot reducing gas, passing said hot reducing gas upwardly in countercurrent contact with the descending residue while maintaining an external portion of said zone at a constant temperature by indirect heat exchange, removing the resulting coke from a lower portion of said zone as a product of the process, and removing the resulting gas from an upper portion of said zone as a product of the process. Further according to my invention, petroleum residue is coked by spraying the same into a coking zone into contact with a gas produced in said zone by contacting therein a fuel gas, which can be derived in the process, with a quantity of air or oxidizing medium which, in said zone, is insuificient to completely combust said gas and recovering coke thus produced.

I have now provided a process and apparatus whereby residues can be coked at high temperatures continuously. My invention comprises a process whereby the hot petroleum residue, previously heated by conventional means, is introduced into a coking chamber which consists of a large chamber into which the hot oil is introduced by means of a spray header, the sprays being directed toward a point in the center of the chamber from points around the circumference of the chamber. The hot oil comes into contact with hot vapors rising from the lower portion of the apparatus, thereby heating it to the coking temperature required. A chamber, preferably of somewhat smaller diameter, is connected to the bottom of the coking chamber, and the coke formed drops down into it. Fuel gas and air are injected into the lower portion of this chamber, and the fuel gas thereby undergoes partial combustion, the air being carefully controlled to insure that complete combustion does not occur. This desulfurizes the coke. This combustion process also provides the hot vapors referred to above, which raise the reactants to the temperature required in the reduction process. The coke then drops down into a plenum chamber, from which it is drawn to be quenched and stored. Gas from the coking and combustion are withdrawn at the top of the coking chamber and then can enter the chamber surrounding the entire coking chambers, Where it is used to keep the outside of the coking chamber at a constant temperature. Gases withdrawn from the top of this chamber can be sent to condensation and fractionation for product recovery. In some instances the gases rising from the desuifurization chamber are not sufficient to provide the high temperature required for coking. Additional fuel gas and air, or air alone, can be introduced into the coking chamber, thereby providing extra heat through combustion. In the instance that coke particle size is not as large as desired, pellets can be introduced into the top of the coking chamber, into the oil spray, so that particles are built up by deposition thereon. As an alternate to using the gases from coking for holding the temperature constant in the coking chamber, steam can be generated by using water in the outer chamber.

In order to provide a more detailed description of the invention, reference is now made to the attached drawing. According to the drawing, there is provided a generally vertical shell 1. Within this shell and spaced therefrom is a vertical shell 2, preferably cylindrical, connected by a frusto-conical section to a smaller vertically-disposed shell 3, again preferably cylindrical. An enlarged hopper portion 4 is provided at the bottom of these shells. It is thus seen that there is provided by outer shell 1 in conjunction with inner shells 2, 3 and 4 an annular space 5 suitable for flow of heat exchange medium. There is provided in an upper portion of shell 2 a spray header '6, preferably an annular ring as shown, although other spray means can be provided. Feed stock to be treated by the process of this invention is passed by way of conduit 7 and heater 8 to the aforementioned spray header 6. The stock thus introduced falls downwardly through the shells ,in countercurrent contact with fuel gas and air introduced by way of distributors 9 and 11, respectively, these distributors being fed by conduits 10 and 1 2, respectively. These distributors can again be annular rings as shown, although other fluid distribution means are satisfactory. Combustion of the fuel gas with insufficient air produces a reducing atmosphere, causing desulfurization of the coke in zone 3, the coke having been produced in vessel 2. The desulfurized coke then falls into the hopper 13 provided at the bottom of the vessel, and is removed by way of conveyor 14 or the like. This conveyor is provided with drive motor 15. The conveyor 14 discharges coke onto a productconveyor 16, the coke having been quenched by steam or water introduced into sealing conveyor 14 by way of conduit 17.

Combustion gases and volatiles from coking pass upwardly through the vessel and are gathered in collector 18, again preferably an annular ring. These gases are then passed by way of conduit 19 and can be then utilized for heat exchange by passing through conduit 20 and its associated Valve 21 to the jacket space 5. After heat exchange, these gases are passed by way of conduit 22 and its valve 23 to product separation zone 24, wherein the gases and vapors are separated into such useful products as motor fuel, diesel fuel and fuel gas. As an alternative method of operation, valve 21 is closed and gases from conduit 19 are passed by Way of conduit 29 and its associated valve 30 directly to product separation zone 24. In this instance, temperature control of the coking zone is provided by introducing water through conduit 25 and its valve 26 to conduit 20 and thence the annular space 5. The steam thus generated is removed by way of conduit 22 and conduit 27 with its associated valve 28 for utility elsewhere. Valve 23 is, in this instance, closed, as is valve 21.

In some instances, it is desirable to provide a larger sized coke product than can be practically attained in the operation just described. In this instance, coke particles are charged through hopper and conduit 31, being metered by star valve 32 or a similar device with its associated motor drive 33. The coke particles thus introduced fall into the coking vessel 2 and are coated with feed stock as they fall through distributor ring 6. The thus-coated particles are coked and desulfurized in the manner previously described. Particles thus produced can be recycled to attain the desired size range.

The fuel gas used for heat, and introduced by way of conduit 10 may be hydrogen, methane, or a natural gas rich in these materials. The oxidant introduced by way of conduit 12 is preferably air, although oxygen-enriched air can be used. Water or steam can be used to quench the coked product by way of conduit 17, which should be done before the coke is exposed to the atmosphere.

, The process and apparatus have the advantage of being simple, continuous, and combining a coking and desulfurization into one piece of apparatus. By using a heat exchange medium surrounding the apparatus, steel can be used for construction, since this insures that thermal shock will not occur. The coke produced is of high quality and suitable for metallurgical and electrode coke.

Suitable feed stocks include crude petroleum, petroleum residue, and especially a viscosity-broken vacuumreduced crude oil of relatively high sulfur content. A feed stock comprising crude oil will preferably have a Conradson carbon value between about 15 percent and about '35 percent byweight. A vis-broken vacuum-reduced crude will preferably have a Conradson carbon residue in the range of about 35 weight percent to about 55 weight percent. Such a stock will usually have a ring and ball softening point in the range of about 260 F. to about 360 F. Other relatively high carbon content feed stocks are within the contemplation of this invention. The following specific example is set forth to more fully exemplify preferable operating conditions in the system.

Temperature, F 150 -200 Feed Rate, lbs./hr 300 Plenum Chamber:

Temperature, F 1, 000 900-1100 Quench Temperature, F 400 400-500 On Gas:

Temperature, F 1, 150 1, 100-1, 300

Flow Rate, lbs./hr 27, 745 Gases to Recovery:

Temperature, F-.- 950 900-1, 000 Coke, lbs./hr 11, 400

My invention is particularly adapted to the treatment of high-sulfur feed stock, which can be processed by my invention to produce a metallurgical grade coke in spite of the high sulfur content of the feed. Where I mention high sulfur, I contemplate a sulfur content in the range of about 1 to about 6 Weight percent. Such feed stocks are available, for example, in certain fields in Monagas, Venezuela. The oil feed in Table I is an oil having the following properties.

Gravity, API 9.5 Sulfur, wt. percent 3.99 Pour point, F 70 Viscosity, SUV, 100 F 297,812

Viscosity, SUV, F 39,236

Hempel distillation:

Initial boiling point, F 270 427-482" F 1.0 482527 F 2.5 527585 F 3.3 585-637 F 4.1 637-687 F 4.9 687738 F 5.5 738760 F 4.7 760+ 74.0

1 Vol. percent.

Reasonable variation and modification contemplated within the scope of the invention of this disclosure, drawing and appended claims, the essence of which is that there are provided a process and apparatus for coking petroleum residue which comprises spraying said residue downwardly into a vertically elongated coking zone, introducing into a lower portion of said zone a hot reducing gas, passing said hot reducing gas upwardly in countercurrent contact'with the descending residue, and, in another embodiment, maintaining an external portion of said zone at a constant temperature by indirect heat exchange.

, I claim:

1. A process for coking petroleum residue which comprises spraying said residue downwardly into a vertically elongated coking zone, introducing into a lower portion of said zone a hot reducing gas, passing all of said hot reducing gas upwardly through the entire length of said coking zone in countercurrent contact with the descending residue thereby directly heating the said residue during its entire passage through said zone while maintaining an external portion of said zone at a constant temperature by indirect heat exchange, removing the resulting coke from a lower portion of said zone as a product of the process, and removing the resulting gas from an upper portion of said zone as a product of the process.

2. A process for coking and reducing sulfur content of petroleum residue which comprises spraying said residue downwardly into a vertically elongated coking zone, introducing into a lower portion of said zone a hot reducing gas, passing all of said hot reducing gas upwardly through the entire length of said coking zone in countercurrent contact with the descending residue thereby reducing the sulfur content and directly heating the said residue, maintaining an external portion of said zone at a constant temperature by indirect heat exchange, removing the resulting low sulfur coke from a lower portion of said zone as a product of the process, and removing the resulting gas from an upper portion of said zone as a product of the process.

3. The process of claim 2 wherein said residue comprises a vis-broken vacuum-reduced crude oil having a ring and ball softening point in the range of about 260 F. to about 360 F. and a Conradson carbon residue in the range of about 35 weight percent to about 55 weight percent.

4. The process of claim 2 wherein said residue comprises a heavy reduced crude oil having a Conradson carbon residue in the range of about 15 weight percent to about 35 weight percent.

5. The process of claim 2 wherein said maintaining is effected by passing said resulting gas in indirect heat exchange with said zone prior to removal of said resulting gas as a product of the process.

6. The process of claim 2 wherein said maintaining is effected by passing water in indirect heat exchange with said zone, thereby generating steam.

7. The process of claim 2 wherein coke particles are introduced into said zone and dropped downwardly fi'om an upper portion thereof simultaneously with said spraying, thus serving as nuclei for formation of coke in said zone and controlling the size of said resulting coke.

8. A process of forming low-sulfur coke from a highsulfur content petroleum residue which comprises heating said residue substantially up to its coking temperature, introducing the thus-heated residue into a vertically elongated coking zone, spraying the introduced residue downwardly from an upper portion of said zone, maintaining an exterior portion of said zone at a constant temperature by indirect heat exchange, introducing into a lower portion of said zone a fuel gas and insuflicient oxidizing gas for complete combustion of said fuel gas, burning the thus-introduced gases to form a reducing gas, passing all of said reducing gas upwardly through the entire length of said zone in countercurrent contact with said introduced residue, removing from a lower portion of said zone the resulting low sulfur coke as a product of the process, and removing the resulting gas from an upper portion of said zone as a second product of the process.

9. The process of claim 8 wherein said residue comprises a vis-broken vacuum-reduced crude oil having a ring and ball softening point in the range of about 260 F. to about 360 F. and a Conradson carbon residue in the range of about 35 weight percent to about weight percent.

10. The process of claim 8 wherein said residue comprises a heavy reduced crude oil having a Conradson carbon residue in the range of about 15 weight percent to about 35 weight percent.

11. The process of claim 8 wherein said maintaining is effected by passing said resulting gas in indirect heat exchange with said zone prior to removal of said resulting gas as a product of the process.

12. The process of claim 8 wherein said maintaining is effected by passing water in indirect heat exchange with said zone, thereby generating steam.

13. The process of claim 8 wherein coke particles are introduced into said zone and dropped downwardly from an upper portion thereof simultaneously with said spraying, thus serving as nuclei for formation of coke in said zone and controlling the size of said resulting coke.

14. Coking apparatus comprising a vertically elongated vessel, downwardly directed spray means in an upper portion thereof, indirect heat exchange means surrounding a lateral portion of said vessel, first conduit means communicating between a source of petroleum residue and said spray means, second conduit means communicating between a source of fuel gas and a lower portion of the interior of said Vessel, third conduit means communicating between a source of oxidizing gas and a lower portion of the interior of said vessel, fourth conduit means communicating between an upper portion of said vessel and a point of gas utility, means for removing coke from a lower portion of said vessel and means for dropping particulate coke downwardly into the top of said vessel substantially axially with and interiorly of the spray from said spray means.

15. Apparatus of claim 14 wherein said means for removing includes means adapted to quench hot solids therein.

16. Apparatus of claim 14 wherein said point of gas utility comprises said indirect heat exchange means, and wherein there is further provided fifth conduit means communicating between said heat exchange means and a second point of gas utility.

References Cited in the file of this patent UNITED STATES PATENTS 2,014,212 Seguy Sept. 10, 1935 2,179,829 Pier Nov. 14, 1939 2,323,501 Tuttle July 6, 1943 2,366,055 Rollman Dec. 26, 1944 2,366,057 Russell Dec. 26, 1944 2,732,332 Geller Jan. 24, 1956

Claims (1)

1. A PROCESS FOR COKING PETROLEUM RESIDUE WHICH COMPRISES SPRAYING SAID RESIDUE DOWNWARDLY INTO A VERTICALLY ELONGATED COKING ZONE, INTRODUCING INTO A LOWER PORTION OF SAID ZONE A HOT REDUCING GAS, PASSING ALL OF SAID HOT REDUCING GAS UPWARDLY THROUGH THE ENTIRE LENGTH OF SAID COKING ZONE IN COUNTERCURRENT CONTACT WITH THE DESCENDING RESIDUE THEREBY DIRECTLY HEATING THE SAID RESIDUE DURING ITS ENTIRE PASSAGE THROUGH SAID ZONE WHILE MAINTAINING AN EXTERNAL PORTION OF SAID ZONE AT A CONSTANT TEMPERATURE BY INDIRECT HEAT EXCHANGE, REMOVING THE RESULTING COKE FROM A LOWER PORTION OF SAID ZONE AS A PRODUCT OF THE PROCESS, AND REMOVING THE RESULTING GAS FROM AN UPPER PORTION OF SAID ZONE AS A PRODUCT OF THE PROCESS.

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