US1570131A - Treating petroleum oils - Google Patents

Description

R. B. DAY

TREATING PETROLEUM OILS Filed August 5. 1921 2 Sheets-Sheet 1 Jan. 19,1926. 1,570,131

clay/(slow (w /Bee Jan. 19 1926. 1,570,131

' R. B. DAY

TREATING PETROLEUM OILS Filed Augu'st 5. 1921 2 Sheets-Sheet 2 a 6R Ifl/YG TUBE Patented Jan. 19, 1926.

UNITED STATES ROLAND B. DAY, OF LANSEOWNE, PENNSYLVANIA.

TREATING PETROLEUM OILS.

Application filed August To all whom it may concern Be it known that I, ROLAND B. DAY, a citizen of the United States, residing at Lensdowne, in the county of Delaware and State of Pennsylvania, have invented certain new and useful Improvements in Treating Petroleum Oils, of which the following is a specification.

This invention relates to processes for producing hydrocarbon materials having low boiling points from hydrocarbon materials having high boiling points.

The object of the invention is to provide a process for cracking oils b which liquid petroleum oils are subjected to a continuous treatment within a closed chamber under conditions which reduce to a minimum the possibility of the formation of carbon on the interior walls of the chamber.

The principle upon which the process operates is that an oil in order to be cracked into the greatest possible amount of gasolineor light hydrocarbon must be brought into contact with a heated metal and that thetemperature of the metal and length. of time that the molecule of oil is in contact with the heated metal further controls the degree to which the molecule will react. That is, if a given moleculeis allowed to come into contact with hot" metal the degree to which it will react, and the product that it will make will depend upon the length of time of contact and the temperature of the metal. It has further been proven that di fierent molecules in an oil require different temperatures in order to react to the best advantage, for instance, to form the maximum amount of gasoline. It is therefore necessary to provide in an apparatus for carrying out this process a series of tubes or other suitable arrangement in which the temperature is raised-gradually, as in a set of tubes where each tube is hotter than the last, or in a single tube where specific portions are progressiv ly hotter than previous portions in the same tube.

A particular feature of the present invention relates to the details by which carbon formation is reduced to a minimum. It has been found that oil material may be treated in the liquid phase within a still to the exterior of 'whichheat is a plied, and that sub stantially no carbon wi l adhere to the interior walls of the still provided the oil is subjected .to very severe agitation, that is the oil is moved rapidly overthe inner surface 5, 1921. Serial No. 489,936.

of the still walls. Heretofore when oil was treated in bulk in metal containers by heat applied to the exterior, coke formations rapidly rendered continued operation dangerous because of the weakened still walls, and blow outs due to such formation were common. It has been suggested that scrapers be used within stills to remove carbon formations as deposited, and other operations have included the use of false bottoms within stills. The present invention dispenses with the use of scrapers, and other orms of complicated constructions by providing for severe agitation in accordance with the details of operation of certain apparatus, which details are hereinafter more fully set forth.

It may be briefly stated that the invention involves preferably a tubular still within which is mounted a rotatable shaft having thereon a plurality of paddles or stirrer arms which may be rotated at a speed of about 70 revolutions per minute or faster to cause oil within the tubular still to move around within the still at substantially the same rate of speed. Other details relate broadly to the use of requisite temperatures for cracking, and the fact that the still preferably should be filled full of oil during the heat and agitation treatment.

The process is preferably conducted in the apparatus illustrated in the accompanying drawings, in which:

Figure 1 is a side elevation of a heating furnace illustrating the exterior drive shafts, and showing their connections with the hibular retorts;

Figure 2 is a view illustrating the relative direction of rotation of the agitator shafts looking in the direction of the furnace on Referring in detail to the drawings of the".

apparatus, 1 represents the masonry construction, either concrete, stone or brick, but preferably fire brick, such as will stand severe temperatures. A suitable stack 2 is provided for lea ling off the furnace fumes,

smoke, and gases of combustion. A source of heat is provided by burners 3 located at the lower part of the furnace and fed by pipes 3 and 3 which feed respectively oil and steam. The furnace is braced by suitable buck stays 1 holding the same t-o a suitable masonry or concrete base. The fiame and hot gases from the burner nozzles is projected inwardly and passed upwardly in the furnace over a centrally positioned partition 4', and downwardly to ultimately escape through the stack 2. During the upward movement the heat comes in direct contact with the exterior of a plurality of lon itudinally positioned retort tubes, as w1l be described.

The drawings illustrate three cracking tubes or retort tubes 6 and 7, positioned one above the other and substantially horizontally. lVithin the tubes 5, 6 and 7 are agitator paddles 5 6 and 7 mounted on and adapted to turn with the shafts 5 6 and 7, respectively. The arrangement of the paddles is such that they are rigidly fixed on the shafts and extend substantially at right angles to the line of the shaft. The paddles are arranged so as to be staggered and to form an interrupted spiral, and this arrangement is preferred because the oil'in conjunction with its movement around the interior of the tube also is propelled lengthwise of the tube and thus obtains the benetioial treatment resultant of the progressive movement through the increasingly hotter portions of the apparatus as the lowermost tube is reached, this being nearest to the source of heat. In this manner, also, heavier materials such as any carboii and tarry material will be carried to the lowermost oint in the apparatus and may be drawn 0 It will be noted-particularly that the paddles 5, 6 and 7 are not scraper members and they do not engage the inner surface of the tube walls to constitute scraper members. Preferably the paddles are formed in the Shape of a T. as this form has been considered desirable.

Materials within the tube 5 are passed to the left, referring to Figure 1-, and are dropped through the communicating pipe 8 into the end of the tube 6, and similarly, such materials are passed in the opposite direction in the tube 6 and are permitted to drop through the communicating pipe 9 to the lowermost tube 7, in which latter tube the materials are again moved to the left. The direction of travel of the oil is indicated by arrows. Oil" discharged from the left hand end of the tube 7 may drop downwardly through the outlet pipe 10 which is provided with a valve 11, which latter may be adjusted to provide for the continuous removal of carbon, tar, or other relatively heavy material.

At the top of the system of cracking tubes is positioned a large reservoir for oil which serves as a combined preheating chamber, reservoir and expansion chamber. This chamber is indicated by thenumeral 12, and is provided with an oil inlet pipe 12 for the admission of untreated oil and which may be controlled by a suitable valve 12 for either batch treatment or for continuous operation. A series of test drain spigots 12' are mounted on the chamber 12 at different v elevations to determine the height of the oil therein. A pipe 13 at one end of the chamber 12 leads downwardly from the floor of the chamber to the cracking tube 5. At the other end of the chamber 12 is a pipe 14 leading to the opposite end of the tube 5. A pipe 15 leads from the top of the lowermost cracking tube 7 and is connected to the top of the expansion or feed chamber 12 to carry vapor from the hotter part of the apparatus to the expansion chamber and thence to the condenser. At 16 is indicated a condenser line governed by a weighted valve, and at 17 is indicated another condenser pipe which may lead to a reflux condenser, not shown.

Drive means for driving the shafts 5 6 and 7 b is provided by a main drive shaft 18 mounted in suitable bearings 18 and driven by a pulley wheel 19,.which latter may be operated from any suitable source of power. Referring to Figures 1 and 2, it will be noted that the shaft 18 moves clockwise and turns a sprocket gear 20. which in turn opcrates a dontinuous chain 21. which latter extends over sprocket gears 5, 6 and 7, which are mounted respectively on the shafts 5 6 and 7". The arrows in Figure 2 indicate the relative direction of rotation of the sprocket wheels and the conveyor shafts. At

the opposite end of the cracking tubes is a second drive chain 21 connecting the o ositeend of the drive shaft 18 with the shafts 5 6 and 7".

The process has been satisfactorily conducted in apparatus like that described above in which the retort tubes were of six inch bore and in which the agitating members on the shaft did not constitute scrapers and the ends of which were spaced from the inner walls of the tube. In conducting the process in the above described apparatus, oil is introduced into the expansion chamber 12 through the pipe 12, and from this chamber it circulates downward filling up the difierent tubes of the system. When the agitator members on the shafts are actuated the oil moves downward through the tubes, and at the same time is subjected to the severe agitating movement caused by the high speed rotation of the shaft and paddles. This movement should be about revolutions per minute and might well be faster. Different oils will logically require different speeds and it may-he said that the heavier the oil a correspondingly higher speed is desirable. The process has been conducted satisfactorily on California oils having specific gravities of 11 B. to 12 13.. and yields of 60 per cent 0t cracked distillate were obtained in which specific gravitics of as high as from 30 B. to 40 B. were obtaine l.,. yielding as high as 47 per cent of gasoline with an end point of 190 C. and a specific gravity of, 54 B. In these operations the only carbon formed was in a finely divided state in the heavy tar which was drawn off and which amounted to less than one per cent of the total oil pumped into the apparatus. 7

The blast of flame from the burners .3 provides a temperature in the lower retort higher than the temperature of the upper retort, Thus when a temperature of1000 F. is present in the lower retort, the temperature in the upper retort will probably be about 200 F. less, or about 800 F. The process includes a temperature range varying from 550 F. to 1000 F. and above for the upper and lower retort tubes, respectively. The difference in temperature between the upper and lower tubes is accounted for in part by the distance-from the source of heat, and by the fact that fresh oil is introduced into the upper retort tube. This gradual heating has proved advantageous because every particle of oil is at some time within its travel subjected to the degree of temperature best suited for cracking it. Pressures within theapparatus may vary from 40 to 150 pounds per square inch.

Progressive heating, progressive cracking, surface contact, speed of agitation and time are all variable and interdependent on each other. Time cannot be stated specifically. The important point. however. is that it takes a given fraction of a B. t. u. to crack a given molecule. At a high temperature it would take less time than at a low temperature. Time therefore is used in a molecular sense, and not as a measurement of the time the whole body of oil is subjected to heat. Thus time is dependent on temperature and upon surface contact and varies with these two conditions. The other points, pressure, speed, progressive heating and cracking, are means of putting the principle into eifect. Time, particularly, andsurface contact are important. This does not refer, as stated above. to the time that the total oil is exposed to the heat. but refers to the time that each molecule is in contact with the "hot metal at the right temperature. The speed of the stirring member controls the speed of the moving body of oil and therefore controls the speed of a given molecule travellng along the inner wall of the tube. This is trated in the accompanying drawing serves to carry out the process based on the above statement of principle.

I claim j 1; In the production of low boiling hydrocarbons from high boiling hydrocarbon oils, the process which comprises maintaining a first treatment chamber constantly full of liquid oil, maintaining a pool of oil in a second chamber and at a level above that of said first chamber and constantly connected by a communicating body of liquid with the oil of said first chamber, said communicating'body of liquid extending from the interior and top of said first chamber to the interior and bottom of said second chamber, applying heat to the exterior of said first chamber suflicient to crack some of the oil therein, and leading off aeriform products from above said pool of oil, the even heating of liquid within said first treatment chamber being effected and the formation of carbon on the inner surface of the Walls of said first chamber being prevented solely by violently agitating the liquid material continuously during the application ofheat to said first chamber. 7

2. In the production of low boiling hydrocarbons from high boiling hydrocarbon oils, the process which comprises maintaining two chambers in a furnace constituting a first treatment chamber and a second treatment chamber at a level above said first chamber and spaced from it and connected to it by an open passageway providing ported communication leading from the upper interior of said first chamber into the lower interior of said second chamber. maintaining both said first and said second chambers and said passageway constantly full of liquid oil, agitating the oil in said chambers to prevent incrustation of solid material on the walls thereof, and subjecting said chambers to externally applied heat sutficient to create cracking temperatures within both said chambers, the heat being applied more intensely to said first chamber than to said second chamber.

i 3. In the production of low boiling hydrocarbons from high boiling hydrocarbon oils, the process which comprises maintaining two chambers in a furnace constituting a first treatment chamber and a second treatment chamber at a level above said first chamber and spaced from it and connected to it by an open passageway providing portinterior of said second chamber, maintaining both said first and said second chambers and said passageway constantly full of liquid oil, and subjecting said chambers to externally applied heat suflicient to create cracking temperatures Within both said chambers, the heat being applied more intensely to said first chamber than to said second chamber, the even heating of liquid within said chambers being efi'ected and the formation of carbon on the inner surface of the walls of said chambers being prevented by violently agitating'the liquid material around the interior of each chamber, continuously in one direction in each respective chamber, during the application of heat to said chambers.

In testimony whereof I aflix my signature.

ROLAND B. DAY.

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