US1601730A - Process and apparatus for cracking hydrocarbon oils - Google Patents

Description

Oct. 5 1926. 1,601,730

w. F. FARAGHER Er AL PROCESS AND APPARATUS FOR CRACKING HYDROCARBON OILS Original Filed? Jan. 15, 1921 2 Sheets-Sheet 1 IN VENTORS #Ma. gym A P M M W ATTORNEYS W. F. FARAGHER ET AL PROCESS AND APPARATUS FOR CRACKING HYDROCARBON OILS Original File d Jan. 15, 1921 2 Sheets-Sheet 2 INVENTORS I I A JTORNEYS tillation. This is the 11a of the San wafi short due to the rapid burning out of the Patented 0a. 5, 1926.

UNITED STATES PATENT OFFICE.

WARREN r. rAnAennn'or PITTSBURG 1c 1r. GARNER, or rAwLnY, ENGLAND, Assm oRs or PITTSBURGH, PENNSYLVANIA, A CORPORATION PENNSYLVANIA, AND FREDER TO GULF REFINING COMPANY, OF TEXAS.

H, AND WILLIAM A. GBU SE, WILKINSBURG',

PROCESS AND APPARATUS, FOR CRACKING HYDROCABBON OILS.

Original application filed January 15, 1921, serial No. 437,481, and in Canada December 29, 1921. Divided and this application 'flled larch 28, 1923. Serial No. 628,501.

This invention relates to an improved method and apparatus for making motor hydrocarbon oils, such as the higher boiling fractionsand shale oil disa division of our applicafiled January 15', the invention relates to improvements in the cracking of oil in a horizontal cylindrical boiler type of still heated externally to the cracking temperature.

fuel or gasolene by cracking residual oils of petroleumor tion Serial No. 437,481, 1921; More particularly,

When such ing to the necessity of cleaning the carbon frbm the still walls and the loss of operating operations; while is comparatively time durin such cleanin iron in contact with carbon.

Attempts have been made to overcome the difficulties mentioned by providing stirrers in'the still for agitating the oil, but stirrers are open to the objection that they boxes which must operate heated oil or hotoil' vapors at high pressures.

require stuffing against highly According to the cracking operation is carrie mulation on eration o we maintain an efiectivecirculation of the arranged in permit GlIOlllfiUOIl-Qf oils are subjected to cracking in an externally heated still, serious difficulties are encountered in large scale o tions, due to the deposition of a car onaceous solid, commonly bon on the heated walls of the still. Such adeposition. of carbon interferes with the conduction of heat into the oil, and results in increased .cost of gasolene-production owreferred to as car.-

present invention, the cracking operation is carried out in a horizontally arranged cylindrical still, such as is commonly used in crackin oils, but the out without objectionable carbon deposition and accuthe heated bottom of the still, and with avoidance or substantial .avoidance of the objections above referred to.

In carr ing out the improved cracking opthe present invention, we provi e nal vertical section of line 22 of Figure such oil in the still around the bafiies and between the bafiles and the heated still walls tween the baflles and the still walls so that the ent re body of oil in the still is kept in continuous and effective circulation and ture throughout, and so that objectionable -carbon v eposit on the heated bottom of the still will be revented or removed by the circulating oi. The number of longitudinal baflies provided may vary in shape and arrangement as well as in number, provided they permit effective circulation of the entire body of oil in the manner above described. This circulation takes place alon both sides of the heated bottom of the sti l opposite directions, either toward or away portion of the still; that is, the oil is either .circulated from the center of the still, atthe bottom, upwardly along the sides of the still, 1n opposite directions, and back to the central portion of'the still after passing'between the outer baflles and the still walls, or the oil can be circulated downwardly between the baflies'and the still walls, in opposite direction, to the center of the still at and adapted for the practice of the process of the invention. In the accompanying shows a transverse verticalsectionof line 1-1 of Figure 2, Fig. 2 shows a longitudi- 1 and Fig. 3 is a view similar to Fig. 1 showing a modifiedarrangement. 7

Referring particularly to Figures 1 and 2, the still 1 is a horizontally .arranged cylindrical boiler type of still such as is comthe bottom, and thence returned upwardly.

by the introduction of currents of'gas beheated to a substantially uniform temperafrom the central bottom -manner apparatus embodying the invention,

drawings Fig. 1

uous manner. The oil supply may be automatically regulated in any suitable manner to maintain a constant level in the still. The residue outlet from the still is indicated at 5. The still has a dephlegmating column 26 leading to the vapor pipe and condenser.

Two longitudinal baffles 15 and 16 are provided. These baffles are symmetrically arranged and spaced apart from each other and from the still walls to permit circulation of oil between the baflles and the still walls and between the bafiles themselves. Thesebaflies are extended to a considerable height in the still, preferably to a height not greatly below the normal oil level in the still, so that the oil will be caused to circulate from the upper portion thereof between the baflies, and between the baflies and the still walls, and so that the entire'body of oil will thus be kept in effective agitation and circulation.

Two longitudinally arranged and perforated gas inlet pipes 17 and 18 are provided having a gas supply main 19 with controlling valve 20 therein, and these perforated pipes are arranged in the spaces forming lines between the baffles 15 and 16 and the still wall so that they discharge the gases upwardly into these respective spaces or lines and cause upward flow of oil therethrough., The arrangement of the perforated pipes 17 and 18 is such that they discharge gaseous currents into the oil between the baffles and the still walls thus decreasing the weight of the body or column of oil be-- tween the bafllesand the still walls and causing upward flow of this body of oil. The gas thus introduced acts on the air-lift principle, causing upward circulation of the oil between the bafiles and the still walls and downwardeirculation of the oil in the spaces between the baffles.

The oil is discharged into the main body of the oil near the upper portion thereof, and oilwill be withdrawn from this main body betweenthe inner edges of the two battles. The flow of the oil will thus be a cyclic flow, from the central portion of the main body of 011 thru the spaces between the baffles and the still walls in the opposite direction and back to the central portion of the body of oil. The heating effect is applied mainly to the oil while it is passing upwardly in the spaces between the bafiies and the still walls. The air lift effect of the injected gases and the thermosiphonic effect of the application of heat combine to permit rapic' circulation between the baflies and the stil.

- walls, from the center and bottom outward and upward in opposite direction. Th rapid circulation of oil thereby brought abou1 in opposite directions on the two oppositt sides of the still will have a sufiicient veloc ity to prevent or remove objectionable carbon deposit, thus keeping the still walls substantially free from such deposits and promoting the efficiency of the still as a whole.

The heated oil discharged into the main body of oil near its upper surface will be drawn inwardly by the cyclic circulation anc will blend with the remainder of the body 01 oil, thus bringing the entire body of oil to s practically uniform temperature. The general direction of the paths of the oil during the circulation is indicated by arrows, but it will be understood that the entire body .of oil in the central portion-0f the still will be kept sufliciently agitated and circulated so that it will all be at approximately the same temperature. It will be readily apparent that pipes 17 and 18 might be so arranged or might be replaced by a single pipe, whereby the gases discharged are directed upward thru the aperture between the two baffles 15 and 16. In this case, the injected gases would likewise act on the air lift 'efiect to set up an active circulation thru the body of oil and between the baflies and the still walls over the heated surfaces.-

. In the apparatus illustrated in Figure 3, the same parts are designated by the same reference characters employed in Figures 1 and 2 with a prime appended. The gas supply main 19 is connected to a longitudinally arranged gas inlet pipe 7 arranged to discharge upwardly throilgh the space between the baflles l5 and 16'. The gases are thus discharged upwardly between the baffles and cause a downward flow of oil between the bafiles and the still walls.

a The gas which is used for bringing about the circulation and stirring of the oil may with advantage be the fixed gas formed during the cracking operation, after the con-- densible constituents have been removed therefrom in the condenser, but other appropriate gas can be used, such as natural gas or casing head gas, or other gaseous material, such as steam, which has no objectionable effect upon the cracking operation. This fixed gas may be drawn off at the still pressure, where the condenser is maintained under the same pressure as the still, as in the preferred practice, or at a.

.go objectionable decomposition. gas, resulting from the The introduction of the gas currents not only serves to insure effective agitation and circulation of the oil, in the manner. above described, but it promotes the regular re moval of the lower boiling constituents resulting from the cracking operation, as they are formed, and prevents their remaining in the still for long periods of time to under- The excess cracking operation and from that introduced, can be discharged from the still in any of the usual ways, or a part reused for reintroduction into the stilland the excess discharged from the still or condenser.

In carryingout he process, the oil will be'continuously circulated and continuously heated in such away that the temperature of the body of oil as a whole will be vmaintained at a generally uniform temperature,- with avoidance of objectionable local over-' heating of the oil next to the still wall, and the temperature of the oil will thus be-raised into that range of temperatures most favorable to the cracking operation with the production of considerable naphtha and gasolene and relatively little gas and carbon, and

without objectionable local overheating of the oil to the still higher temperatures at which much gas and. carbon are formed.

This uniformity of temperature of the oil body as a whole is brought about by the continuous and effective circulation of the entire body of oil, with resulting increased uniformity of the oil that is heated by its circulation between the bafiles and the still walls is con tinuously removed so that the formation of a dead layer of oil is prevented, with resulting prevention of the heating ofsuch a layer to objectionably high temperature.

It is one advantage of the invention that it brings about an effective circulation of the oilwithout the -use of moving mechanism and therefore without the use of stufling boxes, so that all connections of the still may be welded and made gas-tight.

Inasmuch as the accumulation of carbon on the still walls is prevented or minimized, the cracking operation can be continued for relatively long periods of time, the oil being supplied continuously thru the oil inlet pipe and the residue being removed continuously or periodically thru the residue outlet pipe. When a considerable accumulation of carbon in suspension in the oil has been brought about, the entire. body of residue Instead of using the still.

the cracking operation, whlle' manner,

can be removed and a fresh charge introduced without the necessity of opening the still to clean it of carbon deposit.

It will be understood that the stills are provided with suitable pressure, temperature and level indicating devices as well as with means for producing and maintaining within the still the necessary temperature and pressure conditions for the cracking operwhen the bottom Wall of the still becomes incrusted with a thick layer of .carbon deposit-or coke.

Owing to the continuous circulation and substantially uniform temperature of the entire oil body, the cracking operation is improved, with high yields of gasolene and lower gas and coke losses, and hence increased capacity or improved yields for a given sized still, while the efiective life of the still is at the same time very materially increased.

The oil feed to the still may be preheated to a greater or less extent before it enters The preheating of the oil can advantageouslybe carried to such a degree as to vaporize and remove any water present therein before the oil enters the still.

In the accompanying drawings, we have omitted the heat insulation or lagging of the still', connecting pipes, etc., but it will be understood that, in practice, suitable heat insulation will be provided to avoid objectionable losses from all exposed parts of the still and of the system which become heated.

From the foregoing description it will be seen that the improved method and appara tus of the present invention, enable the cracking operation to be carried out in an improved and advantageous manner, with eifective agitation and-circulation of the entire body of sultingmniformity' of temperature and of cracking, as well "as with effective circulation of the oil overthe heated bottom of the still and the prevention of the formation'of a dead layer of oil and objectionable carbon deposit on the heated still walls, this circulation of the oil being effected between longitudinally arranged baflles and between such baflles and the still walls, in a cyclic so that 'the oil is caused to flow upwardly or downwardly along the side walls of the still, in opposite directions, either toward or. away from the center of the still at the bottom, while the entire body of oilin the still, and with re-- oil is kept in circulation around the bafiies in such a way that all parts of the oil are effectively agitated and circulated.

In referring to the cracking of oil in the present specification and claims, we intend to include the treatment of various hydrocarbon oils, and more particularly the treatment of higher boiling fractions and residual oils of petroleum or shale oil distillation, for the production of motor fuel or gasolene; but other oils, such as lignite or coal tar, or tar oils, etc., can be similarly treated; and we include all such materials within the term oil, as used in the accompanying claims.

It is to be understood that a plurality of stills of the designs disclosed in this specification may be arranged in series and the oil to be cracked passed thru them consecutively.

We claim v '1. In a method of cracking oils in a horizontally arranged drum still, heated by 'eX- ternal heat over its lower surface, the step which comprises preventing deposition of carbon in the bottom of the still and stagnation of oil Within the still by causing circulation of the entire body of the oil by injecting a gaseous current into a line within the still and at a point within the flue itself.

2. In a method of cracking oils in a horizontally arranged drum still, heated by external heat over its lower surface, the step which comprises preventing deposition of carbon in the bottom of the stilland stagnation of oil within the still by causing circulation of the entire body of the oil by injecting a gaseous current into a fine within the still and at a point within the flue and adjacent the lower extremity thereof.

3. An apparatus for cracking oils comprising a horizontally arranged drum still, means for heating said still externally, means for preventing deposition of carbon in the bottom of the still and stagnation of oil within the still consisting of baiiies spaced from each other which, with the wall of the still, form flues, and means for introducing a gaseous current into each flue at points within the limits of the fines.

1. An apparatus for cracking oils comprising a horizontally arranged drum still, means for heating said still externally, means for preventing deposition of carbon in the bottom of the still and stagnation of oil within the still consisting of bafiies spaced apart and in spaced relation to the lower portion of the wall of the still, and means for introducing gaseous currents into the spaces between the baflies and the wall at a point between the extremities of the upper and lower edges of each bafiie.

5. An apparatus for cracking oils comprising a horizontally arranged drum still, means for heating said still externally, means for preventing deposition of carbon in the bottom of the still and stagnation of oil within the still consisting of longitudinal baffles in said still spaced apartand in spaced relation to the lower portion of the wall of the still, providing confined circulating paths over said lower portion'of the wall, and means for introducing gaseous currents into the spaces between the bafilcs and the wall at points within the spaces and near the lower edge of each battle.

6. An apparatus for cracking oils comprising a horizontally arrangeddrum still, means for heating said still externally, means for preventing deposition of carbon in the bottom of the still and stagnation of oil within the still consisting of longitudinal batiies in said still spaced apart and in spaced relation to the lower portion of the wall of said still, providing a Confined circulating path over saidlower portion of the wall and means for introducing a plurality of gaseous currents within the limits of the confined circulating path for elfecting circulation of the oil cyclically from the central portion of thestill over said path.

In testimony whereof we affix our signatures.

WVARREN F. FARAGHER. WILLIAM A. GRUSE. FREDERIC H. GARNER.

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