US2061792A - Method of reactivating hydrocarbons - Google Patents

Description

J. R. PA RTE N.

SYLVESTER DAYoN Nov. 24, 1936.

s. DAYsoN ET AL METHOD OF REACTIVATING HYDROCARBONS Filed Dec. 22, 1952 Patented Nov. 24, 1936 aigri P AT E T FFI CE METHOD F REACTIVATING HYDROCARBGNS Sylvester Dayson, Baird, Tex., and Jubal R. Parten, Shreveport, La.

Application December 22, 1932, Serial No. 648,326

1 Claim.

The invention relates to an improvement in processes of treating hydrocarbons and in the composition of products obtained by such processmg.

It is one of the objects of the invention to provide a method of refluxing the polymers drawn ofi from the process of treating hydrocarbon oils and re-introducing such polymers into the stream of cracked oils entering the process. l0 Another object of the invention is to re-introduce the polymers from the process so that the gums of the polymers are combined with the tars of the crude entering the process and producing a superior grade of fuel oil.

l5 Another object of the invention is to permit separation of the lighter and heavier fractions from the fractionating column and refluxing the heavier fractions into the top of the fractionating column to control the end point of the fractions 20 issuing from the column.

Another object of the invention is to provide a method of making up a composite charge for treatment by mixing chargesy of cracked oils, reduced kcrude and hot polymers.

Another object of the invention is to provide a method ofl treating hydrocarbons wherein the heavier fractions are reiluxed through the frac-V tionating column and the hot polymers from the refractionator are re-introduced into they charge entering the process; and wherein also the lean oil drawn from the fractionating column is reintroduced into the absorber tower in order to rabsorb the gasoline from the gas being discharged from the system.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawing wherein:

Fig. l isa diagrammatic side view of a sche- 40 matic arrangement of the Various pieces of equipment which may be used in practicing the invention.

Various processes and pieces of equipment have been devised with a view of increasing the yield 45 of gasoline obtainable from crude oil by the cracking and other processes. These methods and equipment have resulted in a material in crease in the yield and in the quality of the fuel obtainable. With the present invention, how- 50 ever, it has been found that the yield may be further increased by resorting to various arrangements of the parts and reiluxing some of the fluids.

Some of the principal contributions include the 55 mixing of the hot polymers with the entering charge, and the reiiuxing of the fractionating columns and the reactivating tower.

Reference may be had to the accompanying drawing, and particularly Fig. ,1, where the schematic arrangement illustrates a pipe or conduit 2, 5 through which a charge of cracked oils must ow in entering the system. This pipe may lead from any desired type of still wherein the crude oil has been cracked. In the processes now in general use, the temperature of the cracked charge through the pipe 2 approximates 950 F. Instead of directing this cracked charge from the pipe 2 directly into the fractionating column 3, the conduit Z'is led into what may be termed a mixing chamber 4. This chamber may take any del5 sired form and it has merely been illustrated `in elevation here las a housing or container. Connected to this mixing chamber 4 is another conduit 5, through which it is intended to introduce a charge of reduced crude oil. This charge of crude comes into the mixing chamber 4 at about 500 F. The fact that this reduced crude charge is cooler than the cracked charge tends to equalize the temperature of the two charges, so that they will not be entering the fractionating column at so high a temperature. l

As is now well understood, the charge of fluid entering the fractionating column progresses through the proces so that the lighter fractions are removed and the heavier fractions separated out as polymers. These polymers have heretofore been drawn off as a waste product. It is contemplated, in connection with the present invention, however, to reprocess these polymers by introducing them into the mixing chamber 4 35 through the conduit 6, the object being not only to reprocess the polymers butvalso to mix the residue from such reprocessing with the tarsvfrom the cracked and reduced charges also entering the fractionating column. With this in mind, it will be observed that the cracked charge from' the pipe 2,the reduced crude charge from the pipe 5,andthe charge of hot polymers from the pipe G, all enter the mixing chamber d. TheV hot polymers, entering the mixing chamber at about 300 F., serve 45 to further reduce the average temperature of the charge through the pipe 'i into the fractionating column. It is desirable that the temperature of the fluid entering the fractionating column be not too high, and it has been found that while the above temperatures are approximate, they result in a very satisfactory charge entering the fractionating column.

The fractionating column is indicated generally at .3 and contains the vaporizer section l0,

the accumulator section II and the fractionating section I2. These sections are preferably of standard type and the vapors rise in this column to the cap I3 thereof where they escape through the pipe I4. The heavier fractions will fall by gravity into the base I5 of the fractionating column and may be withdrawn through the pipe I6 as a suitable fuel oil.

As previously indicated, the fuel being drawn oif from the base I5 is an improved grade of fuel oil over that now generally obtained, because the heavier fractions falling to the base of the column contain not only the tars fromV the crude' charges but also a percentage of gums from the f hot polymers which are being reprocessed. This combination of gums and tars provides an improved fuel oil which is one of the products of' the present system.

The fractions discharging from the fractionating column through the pipe I4 pass to the junction point 2U of the pipes 2Iv and 22. The junction point 20 is preferably positioned in the pipe I4 so that the pipe 22 extends away from the junction in a vertically downward direction; thus the heaviery fractions will tend to'fiow into the pipe 22' while the lighter fractions will pass into the pipe 2|. A suitable valve-23' controls the pipe 2If.

This valve is: know as an equalizer valve and may be adjusted to obtain the desired pressure differential. It is intended that the pressure in the reactivating tower 34 will be slightly greater than the pressure inthe reiiux drum 2'I'. This causes the heavier fractions to pass into the pipe 221 andA the lighter fractions to pass into the pipe 2|'.

The apparatus indicated generally at 25 comprises a set of condensers for condensing the heavier fractionswhich have passed intothe pipe 22 from the junction 20. From the condenser 25 these heavier fractions enter the reflux drum 2f'I' where a separation .of the liquids and the vapors is made. It is intended that a constant level of liquid and a substantially constant vapor pressure" will be maintained" in this drum. To accomplish this, a float control is indicated generally at 28 andmay be of anywell known type. This float control serves to maintain a balanced pressure in the reflux drum.

It seems obvious that the lighter fractions from theV refiuxf drum 21 will pass into the pipe 30 and escape into the system in a manner which will belater described. 'Ihe liquids in the reflux drum, however, are to be recirculated in the system and'with this in mind the pump 3I has been provided. This pump 3| conveys the liquids thru the pipe 32 where the liquid enters the top of the fractionating column as at 33. It will be appreciated that the temperature of this liquid entering the point 33 is considerably lower than the temperature of the top of the fractionating column. Itv is intended that the pump 3| will be connected to a thermostat or suitable thermocouple in the top I3 of the fractionating column. This thermostat will control the operation of the pump 3I= sotha-t it will discharge at the point 33 a sufcient volume of the cooled heavier fractions to maintain a constant temperature in the top of the fractionating column.

Thus, ifa 400 F. end point gasoline is required, the control of the pump 3I will be set to vary within approximately a 1/.3L7 of the temperature on either side of the desired end point. The discharge of theseheavier fractions into the light vapors in the fractionating column causes the heavier fractions to be reprocessed and some additional yield obtained therefrom. With this construction a very accurate end point can be maintained and at the same time the heavier fractions are being refluxed through the system.

The lighter fractions, having been separated at the junction 20, flow through the pipe 2i and enter the reactivating tower 34. A suitable steam inlet 35 may be connected into the line 2| if desired.

The reactivating tower 34 is provided in order to polymerize the fractions there entering and to removeV the objectionable constituents in order to obtain a more perfect fuel. With this in mind, the reactivating tower 34 embodies a housing 36, which is arranged to contain a quantity of clay or suitable lter 3"I. This body of clay is preferably supported by means of a base 38, which in turn supports a filter or screen 37S. A discharge pipe 4U serves to remove the charge of clay when the same is to be removed or replaced.

The pipe 2| is indicated at the top of Fig. 1, and it is through this pipe that the vapors enter the housing 36. The major portion of the vapors entering the housing 36, however, pass through a body of clay 31 into the chamber 44, at the base of the housing. It is contemplated that therev will be two outlets from the base of this housing, a pipe 45 leading to the refractionating column for the lighter of the polymers obtained after the passage of the vapors through the clay body, and, second, an outlet 43 leads to the base of the final refractionating column 43, so that the heavier polymers will be discharged near the base of the refractionating column.

The filter or screen 39 disposed onthe base 33 may be of any desired form such as Monel metal, rock wool or other suitable material.

In the system as here practiced it is contemplated that the body of clay 3] within the reactivating tower may be re-washed when desired by circulating a iiow of liquid through the pipe 50 from the gas separator 5I by means of a pump The liquid forced through this pipe 5G by the pump 52 is a portion of the finished gasoline which has passed completely through the system. The object of drawing off a portion of this finished product is twofold, one being to control the temperature in the top of the reactivating tower 34 by introducing the desired volume of gasoline which is much cooler than the temperature ofthe reactivating tower, because this gasolineV has passed through the refractionator and the gas separator. The pipe line 53 is shown as entering the top of the reactivating tower 34.

The other purpose of refiuxing a quantity of gasoline in this manner is to provide for washing the body of clay 3l within the tower. Thus, if the clay becomes clogged to any extent wherein it is not functioning satisfactorily, then the pump 52 may be set in operation and the clay can be flushed with a rich mixture of gasoline which will wash out the gums deposited in the clay and prolong the vservice obtainable from the clay. The gums carried out of the clay by the gasoline pass into the base and through the pipe 45 or 46 into the final refractionating column, as heretofore described. It seems obvious that this is merely a refluxing operation which tends to prolong the service obtainable from a charge of clay in the reactivating tower and at the same time control the temperature of the clay tower.

The liquid from the pump 52 also serves to control the temperature in the top of the iinal refractionating tower. This is accomplished by lil means of the branch pipe 54, which leads off from the pipe 5U and enters the topof the refractionatn ing column 53, as at 55. The valves 5G and 51 control the pipes 53 and 54, respectively. The adjustment of these valves controls the iiow of gasoline through the pipe 55, so that the temperature of the clay tower and the refractionating column may be accurately determined. Gasoline flowing into the top of the refractionating column 43, not only serves to cool the rising vapors in the refractionating column, which is in the form of a bubble tower so that the lighter vapors will rise to the top and the heavier vapors will sink to the base 6!) thereof, but, also, serves to wash the rising vapors and prevent carrying over of the lighter polymers. The lines 6I indicate the baffles or plates which are usually provided in bubble towers of this type.

The heavier gums and polymers from the reactivating tower will accumulate in the base 65 and one of the most important features of this invention is the reprocessing of these polymers thrown oi from the base 55. To accomplish this a pump 5l is provided which discharges into the line 5, which has been previously described as entering the mixing chamber 5. The return of these polymers to the entering charge increases the yield of gasoline because the polymers are again introduced into the fractionating column after they have been once processed and the return of these gums to the beginning of the process causes some of the gums to be deposited in the base l5 of the fractionating column, so that the gums are mixed with the tars thrown down from the crude which enters the column and in this manner an exceptionally high quality of fuel oil is obtained from the system and discharged through the pipe I6.

The discharge from the nal refractionating column i3 will be a gum-free product and occurs through a pipe 53. This pipe is connected to the condensers 55 to condense the vapors from the refractionating column, so that the gasoline will enter the separator 5l through the pipe 55. This gasoline entering the separator 5l contains a percentage of what is known as xed gas which is separated from the liquid in this separating tower. The gas separated in this tower escapes through the discharge pipe 56.v whereas the liquid or finished product gasoline flows out through the run down pipe 61 to a suitable sto-rage or for consumption as a finished product. A bypass line 55 is provided on the side of the separator so that any desired level may be maintained within the separator.

The pipe 5t joins the pipe 3] previously described and these two pipes are combined in a conduit 59, it being understood that the vapors passing into the pipe 69 are very rich in gasoline because the product in the pipe 30 has escaped from the top of the reflux 'drum and the product in the pipe 66 is the separated gas from the gasoline. Before discharging this Xed gas from the system it is desirable to remove the gasoline therefrom and with this in mind the pipe 69 enters the base 9i) of the gasoline absorber ll. This may be in the form of a bubble tower also, and it is intended that there will be maintained in this absorber a circulation of lean oil whichi's drawn oif from adjacent the top of the fractionating column, This lean oil will be circulated through the absorber as a counter-current to the rising gases from the base l of the absorber. To provide for this circulation a pipe 12 is shown as entering the top of the absorber and this pipe 'l2 is shown as enteringnear the top of the fractionating column 3, as at l5. In this manner a quantity of lean oil will enter the top of the absorber and fiow by gravity to the base l thereof Where it will be drawn off by the pump 'l5 and forced into the pipe 16, which is shown as entering the fractionating column 3, as at l1. In this manner the rich gasoline is caused to bubble through the lean oil so that-the lean oil will absorb the gasoline from the rich gas and the gas thus dried will escape from the absorber through the pipe 79. Control of the flow through the pipe 19 will be had by the valve 8l).

While the apparatus illustrated in the drawing herewith is more or less diagrammatic, it is intended that any desired apparatus may be used in practicing the invention which broadly contemplates reprocessing of the polymers and reiuxing the vfractionating and reactivating towers in order to increase the yield of gasoline and to provide an improved grade of fuel -oil while maintaining an accurate control of the temperatures in the column.

What we claim as new is:

A process of increasing the yield of gasoline from hydrocarbons which comprises iractionatn ing the cracked crude oils, leading off the lighter constituents of the fraction thus obtained to a reactivator, passing the heavier constitu-ents back to the top of the fractionating column to control the end point, reactivating the lighter constituents, refractionating the reactivated fluid and drawing oi the accumulated polymers, reuxing the polymers so drawn off by introducing them into the cracked charge entering the process, .introducing with the cracked charge and the polymers a charge of reduced crude oil to control the entrance temperature of the composite charge.

SYLVESTER DAYSON. JUBAL R. PARTEN.

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