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“3* c. w. STRATFORD 2,126,420 METHOD FOR HEATING AND FRACTIONATING HYDROCARBON OILS ‘ ' Filed Dec. 18, 1933 C57R6U/9DE 2 Sheets-Sheet 1 % INVENTOR ‘ GM “Sf/‘afford c. w. STRATFORD 2,126,420 METHOD FOR HEATING AND FRACTIONATING HYDROCARBON ‘OILS Filed Dec. 18, 1935 2 Sheets-Sheet 2 ENVENTOR - CW. Sr‘rzvfora’ .13" ’» / ATTOR “ EY Patented Aug. 9, 1938 2,126,426 UNITED STATES PATENT OFFICE 2,126,420 ll/IETHOD FOR HEATING AND- FRACTIONAT ING HYDROC'ARBON OILS Charles W. Stratford, Paris, France, assignor to Stratford Development Corporation, Kansas City, Mo., a corporation of Delaware Application December 18, 1933, Serial No. 702,883 4 Claims. My invention relates to a method for heat— ing and fractionating hydrocarbon oils. In the processes and apparatus of the prior art wherein oil is heated and ?ashed into a 5 vlfractionating zone in a single ?ash operation, dif?culty is experienced in obtaining maxi mum yields of desired products. The charging rate can be varied only through certain limits. Diiferent types of crudes have di?erent boiling 10- ranges which fact makes it necessary to espe a. The charging rate. b. The type of oil. Another object of my invention is to provide a method of fractionating oils in which the re boiling load may be varied from zero to the 5 maximum permitted by the capacity of the heater. Another object of my invention is to provide a method of operating a heater to clean it by flow ing oil in such a manner as to preclude carbon particular type of crude used in processes involv ing conventional methods. When pipe stills are deposition on the heating surfaces. 10 Another object of my invention is to provide a fractionating method which will permit the securing of maximum yields of desired products used as a means for heating the oil, the furnace of great uniformity and over a Wide range. cially design fractionating‘ equipment for the l5‘ temperature to which a pipe still must be ?red is governed by the charging rate, the type of oil charged and the amount of oil to be vaporized. In fractionating problems where a number of re boilers are used for supplying heat in the bottom 20 of the fractionating towers, the heat for reboiling cannot readily be supplied by the pipe still which heats the oil for fractionation, since varying quantities of heat must be supplied for reboiling. It will be seen that the present systems of heat 25‘ ing and fractionating oils are not ?exible. The type of crude upon which they operate can be varied only. within certain limits. The charging rate at which the plant is to be operated can be varied within comparatively narrow limits. In heaters which employ brickwork, the re fractory material becomes highly heated and, when it is desired to shut down the furnace, it is necessary to keep on circulating oil even after the ?re has been extinguished. Then, too, in fur 35 naces employing brick work, the cost of main taining the brick work is considerable, due to the high temperatures of ?ring. One object of my invention is to provide a method of fractionating hydrocarbon oils which 40 vpossess flexibility of, a. Control. I). Desired products. 0. Charging rate. 4511 (Cl. 196-73) (1. Charging stock. Another object of my invention is to provide a method of heating oil in which the oil flows in a thin ?lm at progressively increasing velocity. Another object of my invention is to provide a novel method of furnishing the heat of reboil ‘ing which will permit a ?exibility and accurate control. Another object of my invention is to provide a heating method having a high ei?ciency. Anotherv object of my invention is to provide 55 ‘i a method for heating oil independent of, In the accompanying drawings which form part 15' of the instant speci?cation and which are to be read in conjunction therewith and in which like reference numerals are used in the various views to represent like parts: Figure 1 is a diagrammatic representation of one mode of apparatus capable of carrying out the process of my invention. Figure 2 is a diagrammatic sectional elevation of the heater used in my process. Figure 3 is a sectional view taken on a line 25 3-3 of Figure 2. Figure 4 is a sectional view taken on a line 4--4 of Figure 2. Figure 5 is a sectional View taken on a line 5-5 of Figure 2. 30 Figure 6 is an enlarged fragmentary sectional View of the portion of the heater shown in Figure 2. In general, my invention contemplates the es tablishing of a circulating stream of a fairly 35 heavy oil from a reservoir through a heater and back to the reservoir. The circulating oil is that previously separated from the process and may comprise a crude from which the desired lighter products such as gasoline, naphtha, kerosene, and 40 gas oil have been removed. The absence of light products insures that the oil may be heated to desired temperatures without the formation of vapors so- that the heater will always be operated completely full of liquid precluding the formation of vapor in the heater which would tend to insu late the oil to be heated from the heating sur faces. The stream of oil is circulated at high velocity and at a constant rate. Another pump takes suction from the reservoir and discharges to any desired number of heating units through which the oil to be heated passes in heat ex change. From the various heating. units, the oil is returned to the common reservoir. It will be seen that the quantity of oil passing through the 2 2,126,420 heater may remain constant while the reboiling load may vary from zero to the maximum. The heater comprises structure which will per mit a mass of oil to be ?owed at high and pro gressively increasing velocity toward the ?red end of the heater. A convection section is ?tted to the heater. The crude is charged through a series of heat exchangers through the convec tion section and into the ?rst fractionating tower in which a desired light product such as gasoline is removed. In the ?rst tower, the bottoms are reboiled by means of heat supplied by a stream of oil withdrawn from the reservoir. It will be appreciated that in this manner close control 15 and great ?exibility are achieved. By main taining the bottom of the tower at a predeter mined temperature, maximum yields of the de sired product can be obtained. The partially topped crude is then heated by heat exchange 20 with a second stream of oil drawn from the reser voir, and passed into a second tower from which a second desired product is withdrawn overhead. The bottom of the tower is reboiled by a third stream of oil withdrawn from the bottom of the 25 reservoir. The topped crude is then introduced directly into the heated stream of oil which is circulating from the heater. The oil is heated to the desired point in the heater to permit of the vaporization of gas oil and lighter fractions. The quantity of oil flowing through the heater is comparatively great in proportion to the topped crude being admixed with the heated oil. The hot oil will vaporize the gas oil fractions and those lighter, and the admixed vapors and oil are sep 35 arated in a separating zone which is preferably situated at the top of the reservoir. The un vaporized oil will pass to the body of oil in the reservoir. The vapors are taken overhead and fractionated in a tower in which a desired light product, as for example, a naphtha or kerosene, may be recovered overhead while the heavier products such as gas oil may be withdrawn at any desired point. The unvaporized condensate bottoms of the tower are stripped either in an external or internal stripping zone. The 45 stripped condensate bottoms may be then reheat ed in a vacuum still for vacuum distillation as is the customary practice, or otherwise processed. More particularly referring now to the draw ings, oil from the lower portion of separator reservoir l is pumped by pump 2 through line 3 into the inlet ring 4 of the radiant section 5 of the heater 6 which will be more fully described hereinafter. The oil is withdrawn from the out let 1 of the heater and passed through line 8 into the upper portion of the separator reservoir I through tangentially disposed inlet 9, through spiral separator Ill. The oil collects in gutter I l, over?ows on to humped plate l2 and rejoins the body of oil [4 in the reservoir portion of tower 60 l. The oil circulation just described is continu ous, the same quantity of oil being constantly withdrawn and returned. The crude oil to be fractionated, it being understood of course that any oil may be used, crude being taken merely by way of example, from storage tank I6, is pumped by pump I‘! through heat exchanger I8, through heat exchanger l9, through heat exchanger 25, through heat exchanger 2|, through heat ex 70 changer 22, into the convection tubes 23 of the heater from which it leaves through line 24 and is discharged into fractionating tower 25. It will be observed that the oil flows through the various heat exchangers in counter?ow relation. 75 Vapors formed by the heating of the oil are re moved from the fractionating tower 25 through line 26, passed through heat exchanger !8, through condenser 27, into separator 28. In sep arator 28 water is removed through line 25; gas is vented through line 3:3 and the desired product which may be gasoline, for example, is removed through line 3 l. A portion of the gasoline passes through line 32 to the re?ux reservoir 33 formed in the lower portion of the separator, re?ux be ing pumped by pump 36 through line 35, as is well known in the art. The bottom oi tower 25 is maintained at a predetermined temperature by means of heat supplied thereto in reboiler 36 which is substantially a vertical heat exchanger. Pump 37 withdraws oil. from the body of oil I4 15 within separator reservoir ! from which it is pumped through line 38, through line 39, con trolled by valve 45, through reboiler 35. Valve as may be a temperature controlled valve so that, as the temperature of the bottom of the tower 25 20 drops, the valve Ml will tend to open, permitting a greater quantity of hot oil to circulate through the reboiler. The tower bottoms pass through line all, through the reboiler, and return to the tower through line 42 by thermo-siphon flow. 25 It will be observed that the unvaporized oil withdrawn from the bottom of fractionating tower 25 through line 53 is the crude minus the desired light fraction. The partially topped crude is pumped by pump 44 through heat exchanger 45 30 in which it is heated by hot oil from the body of oil l4 coming from line 38 through line 4B, through line 41, in counter?ow with the partially _ topped crude in heat exchanger 45, through line 48, where it joins the oil coming from reboiler 36, 35 through line 49. The oil from reboiler 35 and heat exchanger ‘i5 passes through line 55 into line 5|, which discharges into separator reservoir into the gutter l I thereof. The partially topped crude, heated in heat exchanger 45 passes through line 52 and is discharged into fractionating tower 53. The bottom of fractionating tower 53 is main tained at a. given temperature by means of re boiler 54 which acts similar to reboiler 36 and is supplied with hot oil from the body of oil I4 by 45 oil withdrawn from line 45 through line 55, which is controlled by valve 56 and is returned through the reboiler and line 5'! which communicates with line 5|. Line 5| is the common line for return ing all of the oil, with exception of oil to HJI 50 through line 86, that is withdrawn from the body of oil I4 by pump 31, to the body of oil. The bot tom of the tower being maintained at a given temperature, a maximum yield of the ' desired product will be obtained. Vapors of the desired 55 product are taken overhead through line 58, pass ‘through heat exchanger l9 into condenser 59 and thence into separator 65, which is similar to sepa rator 28. Re?ux from the re?ux accumulator 6| in the bottom of separator 65 is pumped by pump 60 62 through line 63 controlled by valve 64 into tower 53. The desired product is withdrawn through line 65 and passed to storage. It will be observed that both towers 25 and 53 are provided with lines 66 and 6'5 controlled by valves 68 and 65 69. These lines are for the purpose of admitting steam into the bottom of towers 25 and 53. In event it is desired to repair, clean or inspect re boilers 36 and 54, these lines may be also used in starting. It is to be understood, of course, that in 70 normal operation the reboilers are used and not steam from lines 66 and 61. The topped crude passes from the bottom of fractionating tower 53 through line 70. Normally, tower 53 will be posi tioned above separator reservoir I so that oil from 75 2,126,420 the bottom of fractionating tower 53 may flow through line 70 by gravity. In the drawings, a pump 'H is shown. The topped crude passes through valve controlled line 12 and is discharged into the circulating stream of hot oil in line 8. It will be observed that the oil circulating in the primary circulating stream, that is, the oil from the reservoir through the heater back to the reservoir, is highly heated. The oil in the 3 the quantity of oil in reservoir I is substantially constant. The vapors passing into fractionating tower 15 are fractionated, the desired product being tatken overhead through line 90 and pass ing through heat exchanger 20 and condenser 9| into separator 02, the lower portion of which forms a re?ux accumulator 03 similar to sepa rators 28 and 60, re?ux being pumped by pump 04 through line 05 to tower 15. The desired 110' reservoir is usually maintained at about 600° F. product, which may be kerosene, for example, is The ‘oil leaving the radiant heat section of the withdrawn through line 96 and passed to storage. heater through line 8 is usually only a few de The gas oil fraction may be withdrawn from the grees higher in temperature than the oil entering tower through side stream drawo? and passes the heater due to the fact that the circulation through line 91 through heat exchanger 2|, ; rate is very high. For example, if the rate of through cooler 93, through line 99, to storage. ?ow of the topped crude be about 50 gallons per The heaviest liquid is withdrawn from fraction minute, the circulation rate through the heater ating tower 75 through line I00 and is discharged in the primary circulating stream will be about together with the oil being bled from the sepa 3000 gallons per minute. It is obvious therefore rator reservoir through line 86 into ‘stripping 20: that a large quantity of hot oil ?owing through tower lill in which the heavy fractions are the heater will heat the topped crude joining the stripped with steam entering tower l0! through circulating stream through line 12 to a tempera line £02. The vapors and stripping steam are ture in the vicinity of 600° F. The hydrocarbons passed into fractionating tower 75 through line boiling below this temperature will be vaporized. M3. The stripped bottoms are withdrawn from The oil and vapors are discharged tangentially the stripping tower by pump I00 and passed through a spiral passageway 10 in the top of the through line I 05, through heat exchanger 22, separator reservoir I. It will be observed further through cooler I06, and withdrawn through line that steam may be discharged into a spiral pas I01. Line I01 may pass to the heater of a vac sageway through valve controlled line 13 to fur uum distillation system or to other processing 3,6 ,1 ther assist in the removal of light products from as is well known in the art. In a typical exam the topped crude. The result of this procedure is ple, in which a Roumanian crude was processed, that the unvaporized oil is separated from the oil the oil in the primary circulating stream through vapors. The oil vapors will be withdrawn from heater 6 entered the heater at about 320° C. and the separator reservoir through line ‘M and passed left the same at about 325° C. The bottom of j; to fractionating tower 75. The unvaporized oil fractionating tower 25 was maintained at about will join the main body of oil l4 in the reservoir 180° C. giving a gasoline having an end point of portion of the separator reservoir. It will be about 140° C. The partially topped crude is observed further that the oil in the reservoir and heated in heat exchanger 45 and passed into forming the body of oil I4 is denuded of all prod fractionating tower 53 from which a naphtha ucts boiling below the vicinity of 600° F. so that having an end point of 185° C. was removed, the the oil being circulated through the heater is of bottom of the tower 53 being reboiled to a tem 40" such a nature that it will not become vaporized perature of 250° C. The vapors passing into when heated to temperatures in the vicinity of fracticnating tower 15 through line 74 resulted 600° F. This results in keeping the heating spaces in an overhead product of a kerosene having an i. of the heater liquid full. end point of 275° C. The gas oil was withdrawn Pumps 2 and 31 are mounted from ?anges through line 01. ‘ which are welded to tubular member 16 as will Referring now to Figure 2, a cylindrical shell be appreciated from the drawings. Pumps 2 and 200 is provided with slots 2M and embraced by 31 are driven by electric motors T! and 18, which an annular member 4 provided with a ?ange :3 are secured to the pumps, the assemblies being connection 202 into which the oil to be heated supported from tubular member 16. The tubular passes. Disposed within and surrounded by shell 50 member 16 passes through the reservoir in the 200, I ?t a second cylindrical shell 203, disposed manner illustrated. Within the reservoir, the in spaced relation to shell 200 adapted to form a tubular member is provided with a number of manifold into which oil through slots 20! passes. wholes or openings 00 which are covered by a By reference to Figure 6 it will be seen that coarse screen 8i which in turn is covered with shell 203 is ?tted with nozzles 204. These nozzles a ?ne screen 82. The liquid level of the oil in are disposed completely around the shell 203 at the reservoir is indicated at 03. This level is spaced intervals. It will be appreciated that oil maintained by means of level control 84. Just from manifold 205 formed by shells 200 and 203 60 “below the liquid level 83 swirl plates 85 are ?tted. will pass through the nozzles 204 throughout the 60' The pumps 2 and 31 take suction through the entire area. Disposed in spaced relation within tubular member l?which is supplied from the shell 203 is a third shell 205 which may be cor» reservoir through the holes 80, as will readily be rugated in the manner shown. The space be appreciated by reference to the drawings. The tween shell 203 and shell 206 forms a thin annu 'rliquid level operates in the following manner. lar oil passageway. An annular outlet ring ‘I 65 A bleeder line 86 communicates with the dis~ charge of pump 37. If the level of the liquid drops, air line 0? communicating with level con trol chamber 0d acts to put pressure on dia 70 glphragm valve 80 tending to close the valve and reducing the amount of liquid bled through line 86. If the level rises above the predetermined point, the action is reversed, the valve 88 tending to open and permitting a greater quantity of oil to 75 be bled through line 86. It is thus assured. that communicates with the oil passage 20'! and is provided with a connection member 208. A burner 200 is disposed to ?re the surface of shell 206 which forms in effect a combustion cham ber Zlll. A volute 2H supplies air through air 70 register 2l2 of the burner and is adapted to give the products of combustion a whirling motion. A transition ?ue 2|3 joins a casing 2H5 to the construction just described. Within member 2M a plurality of tubes 23 are disposed forming a 75 2,126,420 convection section, it being observed that the ?rst portion of the furnace described above forms a radiant heat section. A second transition ?ue 2l5 joins an air pre heater 2|‘! of any suitable construction to the convection section. The air preheater 2|‘! is con nected to a stack ‘MB. A blower fan 219 passes air in heat exchange with the hot products of combustion in air preheater 2 l1 and supplies the 10 preheated air through duct 220 to the volute 2| I. The duct 229 is ?tted with a suitable damper 22L In operation, oil to be heated flows through connection 2% around annular oil inlet member 4, through slots ZOI into manifold 205 and is 15 jetted by nozzles 204 against the corrugated sur face of shell Z‘UES. Since all of the oil must flow into outlet ring 1, it will be observed that the oil ?owing through the ?red end in Figure 2 flows in a thin annular sheet to which addi tional oil is constantly and progressively being added, the oil at the convection section end be ing supplied by one ring of nozzles. As the oil passes to the left, more and more oil is added to the ?owing sheet. Inasmuch as the volume of the passageway is substantially constant, the addition of an increasing quantity of oil will result in an increased velocity in order to take care of the increased mass of oil being supplied. Just before the oil enters the annular outlet 30 member ‘I, the oil passageway 29'! is enlarged by tapering the cylindrical shell 20% at 222 for collecting the oil. The combustion gases have been given a whirling motion as pointed out above. rI‘he rate of heat transfer is extremely 85 high due to the fact that the oil is flowing from 'an extended surface in counterflow to the heat ing medium and owing to high velocity flow of impinged 011 against the heated shell. There is minimum loss of radiant heat due to the fact 40 that the heating surface completely surrounds the source of radiant heat. The jetting of the oil against the heating surface and the high rate of flow prevent carbon deposition and in a measure act as an automatic cleaning means, 45 carbon deposits being prevented by maintenance of Very low flow temperature. The heater is easily and inexpensively installed, maintained, and repaired, inasmuch as there is a minimum of brick work. Furthermore, when the furnace is shut down, there is a minimum of radiant 50 heated brick work to continue heating the oil. The cost of brick work maintenance is avoided. A heater of my design has a very high efficiency, being between 87 and 90%. I have used an experimental heater of the type shown for a period of one year and a half, without the ne cessity of cleaning it once. It will be observed that I have accomplished the objects of my invention. I have provided 60 a method of distillation in which maximum yields of desired products are obtained while providing for ?exibility with respect to control and with respect to the types of crudes which can be processed. I am enabled to operate my unit at any charging rate from zero to the maximum. I am enabled to reboil in an ef?cient and flexible manner. It will be observed that the quantity of oil passing through the primary circulation ring in which heat is supplied is unchanged while the reboiling load may be varied at will. Due to the fact that all light products are removed from the primary circulating stream, the heater operates liquid full. Due to the high velocity of flow in my heater, low ?lm temperatures are obtained so that parasitic cracking is avoided. It will be understood that certain features and sub-combinations are of utility and may be em ployed without reference to other features and sub-combinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It 10 is, therefore, to be understood that my invention is not to be limited to the speci?c details shown and described. Having thus described my invention, what I claim is: 15 1. A method of fractionating hydrocarbon oil including the steps of circulating a stream of oil from and to a body of oil, supplying heat to said stream of oil, heating the oil to be frac tionated and fractionating the same in a ?rst fractionating zone, removing vapors from said zone, passing the unvaporized oil in said zone in heat exchange with a second stream of oil circulated from and to said body of oil to reboil the unvaporized oil in said ?rst fractionating zone, removing the unvaporized oil from said zone and passing the same in heat exchange with a third stream of oil circulated from and to said body of oil, fractionating the thus heated oil, and removing oil vapors from the fractionat ing zone. 2. A method as in claim 1 wherein the unva porized oil in the second fractionating zone is reboiled by heat exchange with a fourth stream of oil circulated from and to said body of oil, the unvaporized oil is withdrawn from the sec ond fractionating zone and introduced into the ?rst stream of oil whereby vapors are formed, the vapors separated from unvaporized oil, which is returned to said body of oil and the vapors are 40 fractionated. 3. A method of fractionating hydrocarbon oil including the steps of circulating a stream of oil from and to a body of oil, circulating a second stream of oil from and to said body of oil, sup 45 plying heat to said ?rst circulating stream of oil, heating oil to be fractionated by heat ex change with said second circulating stream of oil, fractionating the heated oil, withdrawing oil vapors from the fractionating zone, separately removing liquid fractions from the fractionating 60 zone, circulating a third stream of oil from and to said body of oil, and passing the liquid frac tions in said fractionating zone in heat exchange with said third circulating stream of oil to re 65 boil the liquid fractions. 4. A method of fractionating hydrocarbon oil including the steps of circulating a stream of oil from and to a body of oil, circulating a second stream of oil from and to said body of oil, sup 60 plying heat to said ?rst circulating stream of oil, heating oil to be fractionated by heat ex change with said second circulating stream of oil, fractionating the heated oil, withdrawing oil vapors from the fractionating zone, separately removing liquid fractions from the fractionating 65 zone, introducing said liquid fractions into the heated ?rst circulating stream of oil whereby vapors are formed, separating the vapors from the liquid oil, passing the liquid oil to said body of oil and fractionating the second mentioned 70 vapors in a second fractionating zone. CHARLES W. STRATFORD.