US2982718A - Pitch conversion - Google Patents

Description

y 2, 1961 G. J. CONSTANTIKES 2,982,718

PITCH CONVERSION Filed July '7, 1958 GAS VENT 3 TO FLUID M PNEUMATICALLY CATALYTIC TRANPORTED CRACKING PULVERIZED REACTOR PITCH DISENGAGING f POT REGENERATED T LEG CATALYST FROM REGENERATOR ELECTRIC VIBRATOR FLOW CONTROL 6 V I0 INERT GAS 7 FEED RISER COOLANT OUT 9 III IN a STEAM u STEAM OIL k INVENTOR.

G. J. CONSTANTIKES A TTOR/VEVS operation.

United States Patent rrrcn CONVERSION Filed July 7, 1958, Ser. No. 746,775

2 Claims. or. 208-113) This invention relates to the conversion of pitch, for example, petroleum pitch. In one of its aspects the invention relates to the conversion of solid pitch by subdividing the same, pneumatically conveying the same to a disengaging zone in which the pitch particles are settled out from the conveying fluid or transport gas and from there through a cooled seal leg into the riser of a fluid catalytic cracking zone. invention relates to the feeding of a pitch to a conversion operation by pulverizing the same, suspending the same in a transport gas, transporting the suspended pitch by way of a disengaging zone to a seal leg leading to a reaction zone, cooling the pitch in said leg to avoid melting thereof, and feeding the free-flowing cooled pitch to said reaction zone from said leg.

In recent times there have been demands for motor fuels which have resulted in accumulation of stocks of hard or solid pitches. The effective and economic use of such pitches has been a continuing problem in the petroleum industry. Solid petroleum asphalt or shale has been suggested to be subdivided and fed to the upper portion of a hot bed of fluidized particles such as coke. However, it is desirable to have an improved procedure or process in which a catalytic conversion can be accomin the presence of the catalyst, and thepitch in the presence of the catalyst. Thus, my conception involves feedng pulverized pitch to the riser of a fiuid catalytic crack- 1ng operation thereby to contact the pitch with a mixture In another of its aspects the a method for conveying a solid pulverized or subdivided pitch material such as petroleum pitch to a catalytic cracking operation which comprises pneumatically transporting the pulverized pitch to a disengaging zone, in said zone disengaging the pitch from the transporting medium, passing said pitch to a settling zone, in said settling zone removing substantially allof the transporting fluid from said pitch, cooling said pitch, and then feeding said pitch to a mass of fluid catalytic cracking catalyst particles. In a specific embodiment of the invention the solid subdivided settled pitch is passed from a seal leg in which it settles upon being separated from the transporting gas through a cooling zone into the feed riser of a fluid catalytic cracking operation and therein added to a just admixed mixtureof catalyst, oil, and steam. The final admixture thus obtained passes upwardly through the riser, in which some desirable cracking occurs, into the reaction zone wherein cracking is completed. In the cracking zone, there is formed coke upon the catalyst and coke particles resulting from the pitch. The catalyst is removed from the reaction zone in the conventional manner of removing catalyst from a fluidrcatalytic cracking zone and passed to a conventional regeneration zone wherein coke is burned from the'catalyst and some of the coke particles reduced in size while other coke particles are substantially consumed, resulting in a mixture of catalyst and coke particles which are found highly desirable for further use in the catalytic conversion operation.

In one modification of the invention when there has been desirably used a high concentration of pitch in the mixture rising to the reaction zone and there has resulted an undesirably large proportion of coke in admixture with the catalyst, the catalyst and coke can be passed through a combustion zone wherein the coke can be burned out from the catalyst down to a desirable proof oil vapor and catalyst, undergoing incipient conversion, just as the precise stage of said conversion at which the pitch is desirably and very advantageously converted and added to the catalytic conversion of the oil. Thus, the pitch is added to a mass of catalyst solids and oil at a time when only a small fraction of conversion has taken place, the catalyst activity is just right for the reaction of the overall final admixture and the dosing in, as it were, of the pitch is smoothly and accurately accomplishable.

It is an object of this invention to convert a pitch, for

portion or level, generating heat useful in the process,

and the process then passed either directly back for reuse in the riser to the reactionzone or by way of the regeneration zone for regeneration, as before.

The process is applicable to the catalytic cracking of pulverized pitch obtained by reducing crude oils, for example, by vacuum flash distillation. Such a pitch, which is desirably converted according to the present invention, has a penetration at 77 F. in 5 seconds with a weight of gramsof zero, a ductility in centimeters with a pull of 5 centimeters per second at 77 F. of zero and a specific gravity of 1.0028.

As an oil, which can advantageously be cracked in the presence of the catalyst and in the presence of the pitch being cracked by the catalyst, there can be used a West Texas topped crude having an API at 60/ 60 F. of 20.

As catalyst, there is advantageously used a synthetic- 87 percent silica-13 percent alumina catalyst subdivided to pass through a U.S. standard sieve mesh screen of atleast 100, preferably 100-400 size.

Referring now to the drawing in which a pitch, an oil, and a catalyst, as described, are employed, a pulverized pitch is transported by an air blast from a storage source, not shown, by way of pipe 1 to disengaging pipe 2 from which air which separates from the pitch passes out by way of pipe 3. Pitch settles into the bottom portion 4 of the disengaging pot which is shaped in the form of a seal leg. The seal leg is provided with an electric vibrator 5 to assure free flow of the pitch. Flow of the pitch from seal leg 4 is controlled by way of flow control gate valve 6. In this embodiment there is provided an inert gas, such as combustion gas resulting from the regeneration of catalyst, as described herein, by way of pipe 7. This gas removes traces of air which might otherwise pass into the operation with the pitch. The pitch moves downwardly through pipe 8 which is surrounded by cooll atented May 2, 1961 aasazta 3f ing means 9 which assures that the pitch shall not melt, due to the proximity of the hot mixture in line 10, and lose its free flowing characteristics. The pitch ultimately is bl'astedinto feed riser 10 by wayof' a steam blast 11. In' feed riser 10 the pulverized pitch is immediately ad'- mixed with a just admixed mixture of steam introduced by Way of pipe 121andoil introduced by way ofpipe1'3". The mixture thus obtained passes'upwardly throughfeed' riser 10 to a fluid catalytic cracking reaction zone, not

shown. After the cracking operation has been completed in the cracking zone, a converted hydrocarbon stream is separated therein from the catalyst and the catalyst sent to regeneration, not shown, from which it is returned in regenerated condition by way of pipe1-'4 to pipe 10. a

In aspecific operation, air at the rate of 3,750 cubic feetper hour andsolid pitch at the rate of 56,100 pounds per hour are transported at a velocity of 30 feet per second by Way of conduit 1 into the disengaging pot 2. The ratio of pounds of solid pitch (of 100 to 200 mesh U.S. standard sieve) per cubic foot of air is to 1. This ratio can range between about 10 to 1 up to about 25 to 1. The temperature of the admixture is maintained at about 90 F., considerably well below the softening point of the pitch. Inert gas is introduced at therate of 275 cubic feet per hour, andin this specific operationflue gas from the regenerator, cooled down to 100 F., is used. Other inert gases, of course, can be employed being used in the range of about 100 to 700 cubic feet per hour on this quantity of solids to strip out air entrained in the pitch in seal leg 4. Although not shown, a cyclone separator can be used in the upper portion of the disengaging pot 2- to prevent loss of pitch fines, when such is necessary.

The pulverized pitch, above-described, flows at rate of 56,100 pounds per hour 160 barrels per hour) and passes by way of the slide valve a into conduit 10 by way of indirect cooling zone 9, which latter zone prevents the solids from melting and coking in conduit 8 due to the proximity of the hot conduit 10. Steam is added by way of conduit 11 at the rate-of about 10,000 pounds per hour to flow the solid pitch into conduit 10 wherein the pitch admixes with the topped crude (West Texas topped crude of'API 60/ 60 F. of steam, and catalyst. The topped crude (partly vaporized) enters byway of conduit 13 at the rate of 1,525 barrels per hour at a temperature of 700 F. Steam is also introduced by way of conduit 12 at the rate of 90,000 pounds per hour. Regenerated catalyst at 100 to 400-rnesh and at 1125 F. is introduced into riser 10 at the rate of 2,800 tons per hour. The admixture of catalyst and total hydrocarbon (topped crude plus pitch) in the riser 10 is at a catalyst to oil weight ratio of 10:1. The quantity of steam to total oil, on the weight basis, is about 0.18 to 1.0. 'In the reactor, not shown, the temperature resulting in the fluidized bed is 925 F., and the pressure is 12 p.s.i.g. Contact time in said reactor is approximately 10 seconds. Product vapors (60 percent conversion) are separated from the catalyst and coke in the reactor and further fractionated and processed as is known in the art. The spent catalyst and coke, after being stripped of occluded hydrocarbons, is regenerated (regenerator not shown) and recycled to the system by way of conduit 14.

Reasonable variation and modification are possible;

within the scope of the foregoing disclosure, the drawing, and the appended claims to the invention, the essence of which is that there has been provided a method and means for pneumatically conveying pulverized pitch to a disengaging zone or pot and from said pot through a seal leg and cooler to a fluid catalytic cracking riser for admixture therein with an admixture of steam, oil, and catalyst substantially as set forth and described herein.

I claim:

1. A method for catalytically cracking a pulverized pitch which comprises suspending said pulverized pitch in a cool transporting fluid, transporting the suspended pulverized pitch to a disengaging Zone located above a feed riser zone of a fluid catalytic cracking operation, disengaging pulverized pitch from the transporting fluid in said disengaging zone, passing the disengaged pulverized pitch as a free flowing solid to a sealzone, passing'controlled amounts of pulverized pitch from said seal zoneto a coolingzone, therein further cooling the pulverized pitch, passing cooled pulverized pitch into said'feed riser zone and-therein admixing said cooled pulverized pitch with an admixture of oil, steam, and catalyst which-hasjust been formed in said feed riser zone, and then conveying thewhole final mixture thus formed into a fluid catalytic cracking reaction: zone and therein convertingsaid' pitch and oil inthe'presence of each other and each in the presencev of said catalyst, and finally recoveringconverte-d hydrocarbons: from said reaction zone.

2. Apparatus for catalytically cracking a pulverizedpitch which comprises means'for suspending saidpulverized pitch in a transporting fluid, means for transporting said suspended pulverized pitch, means for disengaging pulverized pitch from said transporting fluid, said means for transporting the suspended pulverizedpitch'communicating with said'v means for disengaging the pulverized pitch from said transporting fluid, means for feeding an admixture of oil, steam, and catalyst to a fluid catalytic craclfing means and a fluid catalytic cracking means, said means for disengaging pulverized pitchfrom transporting fluid being located above said means for feeding oil and steam to said means for fluid catalytic cracking,-means for cooling disengaged pulverized pitch disposed externally. of said means for feeding an admixture of oil and steam intermediate said means for disengaging pulverized pitch from said transporting fluid and said means for feeding oil and steam to said fluid catalytic cracking means, and means interposed between saidmeans for disengaging pulverized pitch from transporting fluid and said means for cooling'pulverized pitch adapted to accumulate therein pulverized pitch and therefore to act as a sealing section.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A METHOD FOR CATALYTICALLY CRACKING A PULVERIZED PITCH WHICH COMPRISES SUSPENDING SAID PULVERIZED PITCH IN A COOL TRANSPORTING FLUID, TRANSPORTING THE SUSPENDED PULVERIZED PITCH TO A DISENGAGING ZONE LOCATED ABOVE A FEED RISER ZONE OF A FLUID CATALYTIC CRACKING OPERATION, DISENGAGING PULVERIZED PITCH FROM THE TRANSPORTING FLUID IN SAID DISENGAGING ZONE, PASSING THE DISENGAGED PULVERIZED PITCH AS A FREE FLOWING SOLID TO A SEAL ZONE, PASSING CONTROLLED AMOUNTS OF PULVERIZED PITCH FROM SAID SEAL ZONE TO A COOLING ZONE, THEREIN FURTHER COOLING THE PULVERIZED PITCH, PASSING COOLED PULVERIZED PITCH INTO SAID FEED RISER ZONE AND THEREIN ADMIXING SAID COOLED PULVERIZED PITCH WITH AN ADMIXTURE OF OIL, STEAM, AND CATALYST WHICH HAS JUST BEEN FORMED IN SAID FEED RISER ZONE, AND THEN CONVEYING THE WHOLE FINAL MIXTURE THUS FORMED INTO A FLUID

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