US2937136A - Fluid coking to produce a carbon black feed stock - Google Patents

Description

May 17, 1960 J. F MOSER, JR

l FRACTIONATORL.

2 PITCH FEED- FLUID COKER GAS 9 2% NAPHTHA l0 HEATING OIL HEAVY GAS OIL BOTTOMS CARBON BLACK FEED STOCK STEAM Inventor By I Attorney John F Moser, Jr.

United States Patent FLUID COKING TO PRODUCE A CARBON BLACK FEED STOCK Application June 25, 1951, Serial N0. 667,834 4 Claims. or. 208-100) The present invention relates to an improved process for preparing a carbon black feed stock. More particularly, it relates to a process of this nature integrated into the fluid coking operation.

There has recently been developed an improved process known as the fluid coking process for the production of fluid coke and the thermal conversion of heavy hydrocarbon oils to lighter fractions, e.g., see U.S..Patents 2,735,349 and 2,735,806.

The fluid coking process unit consists basically of a reaction vessel or coker and a heater'or burner vessel. In a typical operation the-heavy oil to be processed is injected into the reaction vessel containing a dense, turbulent, fluidized bed of hot inert solid particles. A staged reactor can be employed. Uniform temperature exists in the coking bed. Uniform mixing in the bed results in virtually isothermal conditions and effects instantaneous distribution of the feed stock. In the reaction zone the feed stock is partially vaporized and par-- tially cracked. Eflluent vapors are removed from the coking vessel and sent to a fractionator for the recovery of gas and light distillates therefrom. Any heavy bottoms is usually returned to the coking vessel. The coke produced in the process remains in the bed coated on the solid particles. Stripping steam is injected into the stripper to remove oil from the coke particles prior to the passage of the coke to the burner.

The heat for carrying out the endothermic coking reaction is generated in the burner or heater vessel, usually separate. A stream of coke is thus transferred from the reactor to the burner vessel, such as a fluid bed or transfer line burner, employing a standpipe and riser system; air being supplied to the riser for conveying the solids to the burner. Sufiicient coke or added carbonaceous matter is burned in the burning vessel to bring the solids therein up to a temperature suflicient to maintain the system in heat balance. The burner solids are maintained at a higher temperature than the solids in the reactor. Coke, equivalent to about 5% to 10% based on feed, is burned for this purpose. This may amount to approximately 15% to 30% of the coke made in the process. The net coke production, which represents the coke make less the coke burned, is withdrawn.

Heavy hydrocarbon oil feeds suitable for the coking process include heavy crudes, atmospheric and vacuum bottoms from crude, pitch, asphalt, other heavy hydrocarbon petroleum residua or mixtures thereof. Typically such feeds can have an initial boiling point of about 700 F. or higher, an A.P.l. gravity of about 0 to 20, and a Conradson carbon residue content of about 2 to 40 wt. percent. (As to Conradson carbon residue see A.S.T.M. Test D189 4l.)

It is preferred to operate with solids having a particle size ranging between 100 and 1000 microns in diameter with a preferred particle size range between 150 and 400 microns. Preferably not more than 5% has a particle size below about 75 microns,-since small particles tend to agglomerate or are swept out of the system with the 2 gases. While coke is the preferred particulate solid, other inert particulate solids such as spent catalyst,-pumice, sand, kieselguhr, Carborundum, and alumina can be employed.

The economic attractiveness of the fluid coking process is affected by the production of other valuable products besides the conventional distillate components, e.g., fluid coke for the manufacture of carbon electrodes. It is consequently desirable to be able to increase the number of these products.

This invention provides a process for preparing a carbon =black feed stock by the fluid coking operation. The process comprises continuously fractionating the coker product vapors to separate a heavy gas oil fraction boiling in the range of about 700 to 1000" F. and a heavier fraction boiling above about 1000 F. The heavier, 1000 FJ+ fraction is withdrawn after a once-through operation rather than being recycled as in conventional coking. The heavy gas oil .is, however, continuously recycled and a portion of the approximately 700 to 1000 F.resulting gas oil from the recycling operation is blendedwith the withdrawn heavier fraction to produce the carbon black feed stock. About 2 parts by volume of recracked gas oil is thus blended withabout 3 parts by volume of the heavier fraction. This unique blend of recracke d gas oil and once-through bottoms constitutes a satisfactory carbon black feed stock whereas each stream aloneis not satisfactory. The 'fluid coker is operated at somewhathigher than conventional temperatures as detailed subsequently in the .tabular presentation. V I

This invention will be better understood by reference to an example and the flow diagram shown in the drawing.

In the drawing the numeral 1 is a coking vessel constructed of suitable materials for operation at 1025' F. A :bed of coke particles preheated to a sufficient temperature, e.g., 1200 F., to establish the required bed temperature of 1025 F. is made up of suitable particles of to 400 microns. The bed of solid particles reaches an upper level indicated by the numeral 5. The bed is fluidized by means of a gas such as stripping steam entering the vessel at the stripping portion near the bottom thereof via pipe 3. The fluidizing gas plus vapors from the coking reaction pass upwardly through the vessel at a velocity of l ft./sec. establishing the solids at the indicated level. The fluidizing gas serves also to strip the vapors and gases from the coke which flows down through the vessel to the heater. A stream of solid particles is removed from the coking vessel via line 8 and transferred to the heater, not shown.

A pitch to be converted is introduced into the bed of hot coke particles via line 2, but preferably at a plurality of points in the system. The pitch upon contacting the hot particles undergoes decomposition and the vapors resulting therefrom assist in the fluidization of the solids in the bed and add to its general mobility and turbulent state. The product vapors leave through cyclone 4 and line 6.

The product vapors are then fractionated in fractionator 7. A dry gas fraction is withdrawn through 16, a naphtha fraction through line 9, a heating oil fraction through line 10, and the heavier 1000 Fu-I- fraction through 11. The 700-1000 F. gas oil fraction is continuously recycled through lines 12 and 13 to the coker 1. A portion of the resulting 700-1000 F. gas oil produced from the recycling operation is withdrawn through lines 12 and "14 and blended with the heavier fraction in line 15 to give the carbon black feed stock. About two parts of gas oil are blended with three parts of the heavier fraction.

The actual preparation of carbon black is no part of this invention and the processing of the feed stock thus follows conventional procedures, e.g., see US. Patents 1,535,214, 1,890,188, 1,986,198 and 2,666,734.

The advantages of this process will be apparent to the skilled in "the art. The flexibility of the'fluid coking process is "improved and a valuable feed stock is provided. The conditions in the fluid coker for fuels are also listed below for completeness.

Conditions in fluidpoker reactor Broad I Preferred Range Range Temperature, 900-1, 200' 1, 000-1, 050 Pressure, Atmospheres 1-10 1. 5-2 S ugerfieial Velocity-of Fluldizing Gas,:it./sec-. t 0.2- 0.5-4 00 e Circulation (Solids/oil Ratio) 2 30 7-15 Conditions inheater Broad Preferred Range Range Temperature, F. L 1, 100-L600 1,1751,325 Superfi lal Velocity of Fluldizlng GasflL/sec; 1-5 2-4 It is'tobe understood that this-invention'is not limited to the specific examples which have :been offered merely asillustrations and that modifications may be made without departing fromthe spirit of the invention.

What is claimed is:

1. In a process for coking a heavy hydrocarbon oil coking charge stock by contacting the charge stock at a coking'temperature with a dense, turbulent, fluidized bed of inert particulate solids in a coking zone, the oil being converted to product vapors and carbonaceous solids being continuously deposited on the inert solids in the coking zone; removing-product vapors'fromthe coking zone; circulating the inert solids through an-external heating zone to raise their temperature and recycling the heated solids to the coking zone to supply heat thereto, the improved method of preparing a carbon black feed stock which comprises the steps of continuously tractionating the product vapors to separate a heavy gas oil fraction boiling in the range of about 700 :to 1000 F. and a heavier fraction boiling above about 1000" F.,; withdrawing the heavier fraction; continuously recycling a portion of the 700 F. to 1000 F. heavy gas oilfraction to said coking zone for further cracking; withdrawing the resttof the 700 to 1000 F. heavy gas oil thus produced from the recycling operation and blending it with the withdrawn heavier fraction to produce the carbon black feed stock.

2. The process of claim 1 in which the coking temperature utilized is in the range of 1000" to 1050 vF. 3. The process of claim 2 in which about two parts by volume of the heavy gas oil are blended with about three parts by volume of the'heavierffraction.

4. A process according to claim ,1 .wherein the fractionation of the product vapors is carried out to separate a heating oil fraction 'boiling'between the naphtha fraction and'the heavy gas oil fraction.

' References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. IN A PROCESS FOR COKING A HEAVY HYDROCARBON OIL COKING CHARGE STOCK BY CONTACTING THE CHARGE STOCK AT A COKING TEMPERATURE WITH A DENSE, TURBULENT, FLUIDIZED BED OF INERT PARTICULATE SOLIDS IN A COKING ZONE, THE OIL BEING CONVERTED TO PRODUCT VAPORS AND CARBONACEOUS SOLIDS BEING CONTINUOUSLY DEPOSITED ON THE INERT SOLIDS IN THE COKING ZONE, REMOVING PRODUCT VAPORS FROM THE COKING ZONE, CIRCULATING THE INERT SOLIDS THROUGH AN EXTERNAL HEATING ZONE TO RAISE THEIR TEMPERATURE AND RECYCLING THE HEATED SOLIDS TO THE COKING ZONE TO SUPPLY HEAT THERETO, THE IMPROVED METHOD OF PREPARING A CARBON BLACK FEED STOCK WHICH COMPRISES THE STEPS OF CONTINUOUSLY FRACTIONATING THE PRODUCT VAPORS TO SEPARATE A HEAVY GAS OIL FRACTION BOILING IN THE RANGE OF ABOUT 700* TO 1000*F. AND A HEAVIER FRACTION BOILING ABOVE ABOUT 1000*F., WITHDRAWING THE HEAVIER FRACTION, CONTINUOUSLY RECYCLING A PORTION OF THE 700*F. TO 1000*F. HEAVY GAS OIL FRACTION TO SAID COKING FOR FURTHER CRACKING , WITHDRAWING THE REST OF THE 700* TO 1000*F. HEAVY GAS OIL THUS PRO-

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