US1834696A - Process of heating oil for distillation - Google Patents

Description

Dec. 1, 1931. R. F. GILDEHAUS, JR

PROCESSbF HEATING OIL FOR DISTILLATiON 7 Sheets-Sheet 1 Filed June 17, 1925 $5 viskuxwk disk Dec. 1, 1931. R. F. GILDEHAUS, JR

PROCESS OF HEATING OIL FOR DISTILLATION Filed Juhe 17, 1925- 7 Sheets-Sheet 2 NRA Dec. 1, 1931. R. F. GILDEHAUS, JR 1,834,695

PROCESS OF HEATING OIL FOR DISTILLATION Filed June 1'7, 1925 7 Sheets-Sheet 3 Dec. 1, 1931. R. F. GILDEHAUS, JR 1,834,695

PROCESS OF HEATING OIL FOR DISTILLATION 'Fill ed June 17, 1925 7 Sheets-Sheet 5 anvento'c Dec. 1, 1931. R. F.-GILDEHAUS, JR I 1,834,696

' I PROCESS OF HEATING OIL FOR DISTILLATIQN Filed June 17, 1925 7 Sheets-Sheet 6 awuemtoz Patented Dec. .1, 1931 UNITED STATES RICHARD F. GILDEHAUS, JR, 0F DALLAS, TEXAS rRooEss or HEATING OIL-FOR. DISTILLATION Application filed June 17, 1925. Serial No. 37,639.

This invention relates to a process for refining oil and to apparatus for carrying out the process, and, broadly, the objects of this invention are to provide an improved process for refining oils, particularly mineral crude oils, and to provide an efficient plant and apparatus for refining oils continuously by means of said process. Obviously in its broader aspects, my invention is applicable to other oils, such as vegetable oils, for example, cotton seed oil. Another object of this invention is to provide a process and apparatus for recovering the lubricating oil fractions in their natural state, uncracked, as they exist in the oil being distilled; A further object of this invention is to provide a process for producing oils of high flash and fire and. containing a minimum of carbon forming ingredients, and free of objectionable odor and discoloration, without requiring separate acid treatment. Other objects of this invention will be in part obvious and in part pointed out hereinafter.

It has been found that the heaviest fractions of oils cannot be distilled when heat is applied directly to the still, without partial cracking, even under a high vacuum and with agitation or stirring unless distillation is carried'on very slowly. Otherwise local or spot over-heating ofthe oil occurs, which breaks down the heavy fractions, discolors the distillates and often causes the fractions to carry objectionable odors. If agitation or stirring is increased with a View of preventing cracking while more rapid distillation is attempted, the fractions-over lap, and liquid.

and carbon pepper are"carried over, to an extent depending upon the violence of agita- .tion required for a given rate of distillation.

This destroys the effect of the vacuum as regards promoting separation of the fractions, so lowering the flash and fire of each fraction and darkening their colors. In contrast, in

r my invention there is uniform, smooth, pathflow movement of the oil without violence, at ahigh velocity where the heatis mainly applied and at a low velocity where the vapors pass out of the liquid. Applyingheat indirectly to the still eliminates all overheating, and, together with positive circulation and vacuum, provides means by which rapid heating and distillation may be carried on safely and economically. Such operation under vacuum also causes a'mo're exact sep aration of the fractions and eliminates all cracking, producing oils of higher flash and fire and withless suspended carbon forming ingredients than could otherwise be produced. lie-running oils under this processproduces stable oils of very high color and so viscosity, oils as high as 2500 at 100 F. viscosity with a color of No. 1 N. P. A.-having been produced repeatedly without trouble, and where no acid treatment was used to obtain color.- Operation shows that with indirect heating and positive circulation without agitation the crude oil can be distilled satisfactorily under vacuums ranging from 25.5 inches of mercury to 29.4 inches ofmercury, depending on the gravity of the fractions being distilled; the crude charge under this ran e of conditions being one that has been stripped of all the light ends, including as oil. By indirect heating, I mean heating y radiation or convection from the surface of a heat retardant material having .a-transmission capacity of such value as to prevent the metal heating surface, and consequently the oil in contact therewith, from being subjected to the extremely high furnace temperatures.

The lighter fractions down to and including the cutusually made as gas oil may be taken off uncracked from the treating still or the fractionating still without any vacuum because the heat application is indirect and becausethe oil may be maintained in positive circulation without agitation, although as a matter of fuel economy avacuum of 25.5 inches or more is recommended. Avacuum '90 of 25.5 inches or more of mercury is, however,

necessary when distilling viscous fractions in order to obtain finer separation and better colors, as previously mentioned. Higher vacuums are required as the heavier fractions 06 are taken off, to reduce their boiling point sufliciently below the critical temperature to avoid cracking; and when combined with indirect application of heat to the still and positive circulation, all danger of cracking the 10.

very heavy fractions, each of whose boiling points or temperatures are higher and nearer the critical temperatures, is removed.

By positive circulation, I mean a uniform 5 path-flow movement of the oil through the circuit formed by the still parts maintained by force, by the use of, for example, a force pump connected in the oil circuit; all in contrast with the irregular and turbulent movement which ishad with agitation or stirring In accordance with this invention, the plant or system for the distillation of oils, particularly mineral crude oils, under vacuum, in-

., cludes a treating still in which theoil may be maintained in positive circulation during treatment and a fractionating still in which the oil is maintained in positive circulation during distillation, each having a radiant heat combustion chamber where all or nearly all of the recoverable heat of combustion is and is then conducted to the heating surface dissipated through the walls of and then by radiation from the outer surfaces of a series of ducts made of refractory material having a relatively good heat transmission capacity,

of the still by a subsequent passage of the cooled gases of combustion around and between the ducts, forming the combustion chamber; combined with condensing and cooling apparatus in two stages, aseparating tank, gas cooler, and means for continuously removing the condensate from the separating tank while carrying on fractional distillation under vacuum, consisting of a dry vacuum pump to remove any uncondensed vapors and non-condensable gases, and a wet vacuum pump to remove and discharge the condensate from the separating tank into open tanks continuously.

The condensers are .so arranged as to provide a large area of opening from the still into the condensers, so that the gases pass from the still into the condensers at a. low velocity, reducing to a minimum the danger of their carrying liquid in suspenddarker colors, the efiect depending upon the rapidity of distillation and the velocity of exit. High vacuums expand the" gases of distillation to very large volumes, usually requiring large pipe, 'even with relatively high velocities, and the object of placing the condenser stage immediately upon or 5 closely adjoining the still is toeliminate the necessity of large pipe lines between the 7 the non-condensable gases and the uncondensed vapors (due to the water temperature and vacuum maintained) are separated from the condensate, the condensate passing down by gravity into the suction side of the wet vacuum pump and discharged from it into tanks at atmospheric pressure, as described later. The vapors uncondensed and non-condensable gases are carried through the gas cooler and thence to the dry. vacuum pump. The gas cooler is supplied with cold water, refrigerated if necessary, to condense the remaining uncondensed vapors as far as practicable, and also to reduce the volume of gases and Vapors to be exhausted by the dry vacuum pump. The wet vacuum pump is provided with a speed regulated motor or other speed con trol drive, so that the speed of the wet vacuum pump can be adjusted to suit the rate of distillation, under which condition it will discharge practically a continuous stream of distillate.

In order that a clearer understanding of my invention may be had, attention is hereby directed to the accompanying drawings, forming a part of this application, and illustrating certain ossible embodiments of the invention. Referring to the drawings, Figs. 1' and la together complete a diagrammati cal top plan view of a plant suitable for carrying out the process, the condensate cooler being omitted for clearness; Figs. 2

and 20. together complete a diagrammatical side view of the same; Fig. 3 is a side view of the treating still and its setting in section, the view being taken on the line 3-3 of Fig. 4; Figs. 4 and 5 are each sectional views of the same, and aretaken respectively on the lines 4--4 and 55 of Fig. 3; Fig. 6 is a fragmentary view of the same showing a condenser on one of the still outlets; Fi 7 ,is a side-yiew of the fractionating stil and associated parts of the plant, the still setting being shown in' section, the view being taken on the line 7-7 oi Fig. 8; Fig. 8 is'a. sectional view of the same, and 1s. taken on the line 8-8 of Fig. 7; Fig. 9 is an enlarged detail thereof, partly in section, and is taken on the lines 99"of Figs.j7 and 8;

Fig. 10 is a sectional view of the lower I portion of a modified form of fractionatin still; and Fig.11 is an enlarged section tate the oil and solution while heat is applied line 16, and valve 17, the valves 18 and 19 sure to prevent evaporation of the lighter view of a fragment thereof, the view being ing on the relative height of the still and settaken on the line 11-11 of Fig. 10. Similar tling tank. Both the still and the settling reference characters refer to similar parts tanks are provided with adjustable safety throughout the several views of the draw Valves and pressure regulators (not shown) ings. on the lines 402 and 408, supplying the me- Reference will now be made to thedrawdium with which pressure is maintained. ings. When the still has been emptied, a new charge The crude run may be treated in like manner while the pre- -Valve 1 admits crude oil to pump A, which Vlous charge setflmg and coohng' discharges the oil through valve 2 into line After Setthng Water and Sludge 1s 14 (Valves 3 5 6 7 8 being closed) and drained from the settling tank and the oil is thence into still A bonventional treating taken by pump. A q g Valve and solution consisting of caustic soda and lead charged to the Sun Where 1t 15. gradually heat ed while being agitated with compressed air oxide is pumped Into the st1ll through the to thoroughl; remove an moisture. The

heating here is continued until a temperature of 300 F. is reached, and the oil is held at this temperature until ready for transferring to the fractionating still. The oil may be transferred by pump A through valve 4, line 15, and through valves 27 and and thence into header H of the fractionating still 0. line MValve 87 to pump A and thence As the oil is so charged to the fractionating through either valve 5 or 6 to settling tank fistinlthe PR P or P i be to S or Here the Oil is allowed to cool culate the oil 1n the meantime while heat is then it is washed with cold water and. perbeing applied Pump P-take? oil from the mitted to settle. As soon as the treated crude drum D through i 24 and dlscharges same oil has been removed from still B, another through Yalve 261.nt.header Instead of charge is made as described while the pre transfenmg the Wlth pump same may vious chargehas cooled and has been Washed. be transferred by elther one of the pumps P It has been found in treating certain crudes that the treatment is much more effective at high temperatures, requiring presheing closed. Compressed air is admitted through line 11 and valves 11 and 18 toagito warm the mix to 212 F. Steam may then be applied for further agitation through the line 10 and valve 10'. After a suitable period oftime the mix is then transferred through either valve 21 or 22, depending upon which of the circulating pumps is used for the purpose of transferring the oil, the alternate pump being used for circulation as already mentioned.

After the transfer has been completed, both pumps P and P may be used for circulating the oil within the fractionating still. As distillation takes place, the vapors rise in the condensers C, from which the liquid flows in line 38 to the run-down or cooling coils ofthe cooler E. All vapors not condensed in the condensers C pass out of these condensers through line 36 to the cooler E. Theliquid from the cooler E flows into the same rundown coils as the liquidfrom the condensers coming through the line 38. The liquid from the run-down or cooling coils flows by gravity through line 76, and the vacuum look-box F into the separating tank G. The separating tank G is provided with a gage glass G, so that anyaccumulation of condensate within the separating tank may be readily obcuts and the treating solution. It also has been found that the treating solution separates more quickly when the mixture of crude and treating solution settles under about the same pressure maintained while treating. To this end I transfer the crude and solution to the settling tanks under pressure, by the use t of steam or a non-combustible gas undera range of pressure from 40 to 100 pounds inelusive.

The procedure is as follows:

After the crude and solution have been heated and well mixed by pump circulation under pressure, say of pounds, the settling tank S or S, into which the crude and solution are to be transferred, is charged to a corresponding pressure with steam or a. noncombustible gas through line 400, valved at 401, line 402, valved at 403, and either lines 404 or 405, valved at 406 and 407, depending Servmi p which Settling k to be l The separating tank is provided with a charged Then an q 31 s 11119 13 Opened valved vent 75, and aconnection to the dry between the top of the settling tank and the vacuum pump K, th h valves 41' d 45,

or P through the line 14, valve 3, line 15, and

domes or one of the domes'B of the treatpassing through the gas cooled J. The liqing still B. To provide theequalizing line, uid flows by gravity to thewet vacuum pump a line 408, valved at 409, may join lines and is discharged by same into the look- 400 and 402, and connect with one or more box L, which is provided with a vent-overdomes B of still B through lines 410 and -fiow 68 to permit the oil to escape in case 411. The oil is allowed to flow into the setvalves 52, 53, 54 are closed. From the looktling tank or is pumped into same, dependbox L the oil is directed into tank M or M through valves 52 and 53, or through valves 54, into the manifold R, and from there directed to a series of tanks T. If the oil is directed to the tanks M and M, it may be 5 transferred from same by pump N through line 72 and valve 78, into manifold R.

The wet yacuum pump Y is provided with a speed regulated drive Y, which is adjusted to the rate of distillation so as to give practically a continuous flow of oil from the dis charge of the wet vacuum pump Y, into the look-box L.

The dry vacuum pump K is connected to the gas cooler J, through the valve 45 and line 69, and discharges the non-condensable gases and uncondensed vapors through line 70, into the furnace of the fractionating still. The gas cooler J is provided with cold water circulation (refrigerated, if necessary) through the line 74, valve 42. The water from the gas cooler J passes out through valve 43, into the condenser pan E. The gas cooler d is drained continuously through the valve 48 into a container Q, which is connected to the line 69 by line 77, through valve 47. The

container Q is drained by closing valves 47 and 48, and opening valves 49 to admit air,

while its contents is removed through valve' 50. The gas cooler J is also provided with a by-pass' connection through the valve 46 and line 77, so that upon closing valves 44 and 45, the gas cooler J may be opened for cleaning or any other purpose. I

Water is supplied through the line 73, and

valve 41, to the pan of the condensate cooler required time at this temperature, the tem-' E, which is provided with an overflow line 40. The water circulating pump W takes water from the pan of cooler E through line 39 and discharges same through line 37, and the valve 32, 33 and 34, into the condensers C. The discharge water from condensers C flows out of the line 35.

Procedure for various crude;

The procedure in detail for handling the crude oil varies, of course, with the nature of the crude itself, but three methods may be outlined in general which will cover practically all mineral crude oils:

First: The stripped waxless or coastal crude, or one containing a neg igible quantity of wax, is brought from the s orage tanks by ump A and discharged in -o the treating till. Here the necessary treating solution,-

the conventional mixture of caustic soda and lead oxide, is added and the crude oil gradually heated to 212 F., during which time the oil and treating solution is thoroughly agitated by means of compressed air, supplied through line 11. After being heated for the perature is increased and the oil and solution are agitated by means of steam supplied through line 10. After suitable period of time, the oil is then' transferred to either one of the settling tanks S or S, where the oil is washed with cold water after having cooled sufficiently, and then allowed to settle, and

the sludge and' treating solution removed.

In the meantime the second charge is placed and treated similarly in the treating still,

and'thence transferred to the alternate separating tank. The first charge is then pumped back into the treating still after the'sludge and water have been removed therefrom in the settling tank. In the still' it is gradually heated and agitated with compressed air until all the moisture is driven out, and then the temperature is raised to 300 F. and held at this temperature until ready for transfer-. ring to the fractionating still.

While the procedure described above in. connection with the treating still has taken place, the previously treated charge of oil has been fractionated in the fractionating still. Here the oil is circulated continuously by means of pump P or P, which takes the oilfrom the lower rear drum D of the when there is no more oil remaining in the still body proper, practically all of the heavy bottoms will be contained in the frontdrums. After distillation has been completed. the bottoms are drained from the front and rear .drnms through the opening shown. Then as soon as the still has cooled sufliciently, another heated charge is transferred from the treating still into the fractionating still for another run.

Second: In the case of a crude oil (eitherwaxless or containing wax), containing light ends, the crude is 'first pumped into the fractionating still, or another still similar to it, where it is stripped. The oil is then transdescribed.

Stripping or reducing crude Stripping or reducing the crude may also be done in the treating still beforetransfer ring the charge to the fractionating still, by providing condensers of the form shown on still 0 on the domes of still B and a vacuum condensing system similar to that shown with still 0. For stripping at atmospheric pressure, the wet and dry vacuum pumps may be omitted and the condensate allowed to flow by gravity from the separatin tank (which is then vented) to the tanks M.

ferred to the treating still and handled as last The re-mm The distillate from the first run is pumped to the treating still B, where it is heated (and treated if necessary) to 300 F. and then transferred to still for fractionating under vacuum. The condensate from the separatw ing tanks flows to pump Y, then passes through the vented look-box L into the line 71. Here the oil is directed into the manifold B through valve 54, or to either tank M or M, through valves 52 or 53. Samples 5 of the cut coming over at any time may be taken from the valve opening 59. The tanks lid and M i are measuring tanks, provided with overflow lines to the'waste oil tank Z. The vent'from look-box L is also arranged to drain as shown into tank Z, so that theoil from pump Y may pass through line 68 and thence through 9 to tank Z should valves 52 53 and 54 all remain closed any length 0 time. The measuring tanks have a capacity of approximately 10% of the charge and are calibrated by suitable markings inside so 'that cuts of any desirable quantity may be made on a trial run to determine the points for making the cut in subsequent re-runs of similar distillate to obtain oils of certain flashes or vi'scosities or to obtain the most economical division, which may be observed through the openings in the top of the tank, with the aid of an extension light. The oil in tanks M and M is pumped by ,pump N through line 72 and valve -7 8 into the manifold R (valve 54 being closed) from which it is run to blending tanks (not shown). The subsequent re-runs of similar distillate 4,0 are made without the use of the measuring tanks or pump N, the condensate being directed from line 71, through valve 54, into manifold R, thence through valve 55 into tanks T. The tanks T are gauged from time to time and the condensate is directed to different tanks in accordance with the production schedule established by the trial run.

Treating still and setting Referring to Figs. 3, 4, 5 and 6, the treating still 100 is enclosed in'a suitable built-up setting 101, which also forms an initial combusv tion chamber 102 and a space for ducts-or pas- 'sages beneath the still .The ducts are so arranged in this space thatthe still will be subjected only to indirect heat from the furnace. To this end the setting is provided beneath the still with' lower cross-members 103 and upper cross-members 104 located and designed to support an upper tier and a lower tier of duct members, and to provide a duct passage 105 beneath these duct members. The duet members may comprise tubular tiles of oblong cross-section 106 of refractory material. By placing tiles end to end on the lower cross-members 103, and preferably upright, and in a plurality of lines, side by side, but spaced from each other slightly, a tier of ducts 107' is formed extending longitudinally beneath the still through these lines of. tiles. On the upper cross-members 104 a similar tier of ducts 108 is formed through the hollows of similar lines of tiles. The last tilfe 109 in each lower row and the corresponding tile 110 in the adjacent upper row are specially formed to communicate with each other, and are closed at the end. The furnace is provided with oil burners 111, which may be supplied with air or steam for atomizing, and there is preferably a conventional shutter arrangement for regulating the air admitted to the furnace, in order to obtain the best combustion. Ignition takes place in the furnace 102 and complete burning occurs in the duct passages, forming the combustion chamber, and gases being surrounded by the heated refractory surfaces. The ducts themselves are of suchshape as to cause the gases to mix thoroughly, and so further aid in making the combustion more complete. The gases ,ip'ass from the furnace through the lower tier of ducts 107 and thence forward through the upper tier of ducts 108 into a front chamber 112, from where they pass through two or more large tubes 113 placed in the still body. The connection from the front chamber 112 and rear chamber 114 to the tubes is obtained by ducts 115 of refractory material which do not fit tight, and so provide for an expansion of the still. The tubes themselves are made corrugated for strength and to compensate for expansion. After passing through the tubes of the shell, the cooled gases pass down the rear chamber 114 into an opening 116 in the rear wall, and thence forward, rising between the spaced lines of tiles which form the ducts 107 and 108, constituting the combustion chamber, around the still body and then out the stack opening 117. With this structure I am able efliciently to transmit to the shell, the heat units created by the combustion without at any time subjecting the shell or. tubes to unduly high temperature. 5

As the combustion goes on (it is practically completed in the lower tier of ducts 107) the refractory material of-which these ducts are formed will absorb heat from the gases, so that when combustion first starts the gases will have given up a substantial amount-of heat before emerging from the upper tier of ducts 108 and entering the tubes 113. Of course, if no method were provided of withdrawing heat from these ducts, they would serve only as a heat reservoir, and very shortly an equilibrium would be .estab-- lished so that the gases emerging from the ducts would be substantially the same temperature as though these ducts were nonabsorbent. However, in my arrangement it will be found that the gases which have passed 0 units will then be carried by convection to the shell and its surrounding casing and be 10 transmitted to the oil, which will be heated rapidly and eficiently but without the application of high local temperatures. In other words, I heat the oil (or the shell in which it is contained) in part directly by convec-- 315 tion through the action of the fresh products of combustion and in part indirectly'by the convection of the gases which are reheated by contact with the outside of the ducts.

The still body itself is preferably provided with reinforcements 118-against collapsing,

entirely on the outside, leaving a clear shell,

easily cleaned within. The still body may be suspended from overhead beams 119 by means of rods 120, so that the furnace, combustion 2 chamber and setting walls may be repaired and rebuilt when necessary. The still body may have conventional man holes 121 and domes 122 extending through the top of the setting and covered with suit- 39 able insulation 123.

If desired, the domes 122 may be provided with condensers 124 containing water tubes 125, vapor'bafie 126, vapor outlet 127 and liquid outlet128.

Frwctz'onati'hg still and setting Referring to Figs. 7, 8, 9, 10 and 11, the

fractionating still ody 200 is provided with reinforcement 201 against collapsing entirely 40 on the outside, leaving a clear shell easily cleaned within. The heads may be either dished in or flat. The body is sus ended by means of rods 202 from overhead cams 203 carried on the setting 204. At the end of the setting over the initial combustion chamber 205 and beneath this end of the still tank are drums 206 which communicate with the tank 200 through conduits 207. Beneath the other end of the still are lower drums 208 which communicate with the tank through conduits 209. Extending between these drums is a series of circulating pipes 0r co1ls 210. Oil enters thelower end of each 0011 210 from header H and leaves the open upper end of each coil in the drum 206. During dis- 7 tillation this movement is carried on continuously by the action either of pump P or ump P as previously described. As a result of thisthe oil is moved rapidly through the coils in relatively small mass so that it 'will absorb heat rapidly even though the intensity of the heat transmitted to the coils is substantially below that of the combustion chamber. i B5 -These coils are welded or expanded into the drums and are provided with removable use the return bends and pump circulation.

The capacity of the pumps is such that the flow of oil will be rapid enough 'to eliminate carbon deposits in the tubes in practically all cases, however access to the tubes for cleaning purposes is provided for through the man holes in the drums, and through the removable return bends, so that the straight tubes can be easily cleaned.

In accordance with my invention, the oil circulating in the coils 210 is heated indirectly. To this end the coils are disposed between tiers of ducts 214, 215, 216, which may be constructed of pieces of tiling 217 of refractory material having a relatively good heat-transmission capacity, fitted together with a recessed or interlocking joint, which may be cemented. Angle irons 218 are bolted on the tubes 210, which support the end tile pieces. The setting portion 219 supports the tiling from below. Each line of ducts at oneend communicates with the corresponding line of the adjacent tier of ducts. For instance, referring to Figs. 7 8 and 9, the tiles and tiers {may be so arranged that combustion gases from the oil burners 220 in furnace chamber 205 pass through an opening 221 into and through the lower lines of ducts 214, then ,through the second tier of ducts 215, then through the upper tier of ducts 216, through opening 222 and about the still body, from whence they passthrough opening 223 into flue 224, and outat the stack 225. Preferably thespace 226 beneath the ducts and coils is filled in-w ith insulating material.

By this arrangement heat is being continuously absorbed by the walls of the tiles which are of large area and are of a material which is a good transmitter of heat so that they must act as a heat stabilizer or reservoir. From this reservoir heat is being continually drawn to the coils 210 which are in contact with the walls but as the areas of contact are small the flow of heat from these walls to the coils will not be unduly rapid and the intensity of heat to which the oil in these coils is subjected is much less than is the case 'where the products of combustion come directly in contant with the coils or where the coils are fully imbedded in the furnace walls.

However, the fact that the walls are in contact with'the pipes and space is provided for a flow of gas between the pipes upwardly at an angle .will insure the heat being trans- ,(see Figs. 10 and 11), there may be an open duct passage 228 provided beneath the tiers of tile ducts, which in this case may be arranged in horizontal lines instead of in inclined lines,

as in the previously mentioned arrangement. The arrangement is such that the combustion gases from the furnace 205 pass upwardly through a passage 229 into the upper tier of ducts 230, thence through the second tier of ducts 231, thence into the lower tier of ducts 232, the tiling of these lower ducts having openings 233 in their lower walls, through which the gases pass into the open duct 228, from whence the gases pass through the spaces 234 between the tiles and about the (oils 210 located the-rein- From there the gases pass about the still body and through the opening 223 into flue 224 and stack 225. In this modification the ducts may be formed by means of tubular tiling 235 placed in rows, 'end to end, the end tiles being closed at one end and opening into a corresponding tile in a corresponding line of an adjacent ti'er. The tiles may be supported on suitable crossmembers 236 provided in the still setting, and blocks 237 between the tiers of tiles. In this modification the action is somewhat different than in the previous case, for here convection is a more important factor, while the contacting surfaces for heat conduction are almost negligible. The products of combustion which have given up a considerable portion of their heat to the walls of the tile ducts pass up around the coils 210 continuously giv- I ing up heat to the lower portionsof these coils, then absorbing additional heat from the outside walls of the tile ducts and transmitting such heat to other, portions of these coils. The \residual heat is carried by the gases to the main still body. y

The still body hasa man hole 238 with an insulating cover 239, and has condensers 240, communicating with the still body through conduits 241, which are covered with suitable insulation 242 where they extend above the setting. The condensers have water tubes 243, connecting with water inlets 244 and outlets 245; vapor bafiies 246; vapor outlet 248; and liquid outlet 247.

At the, usual rate of driving, ract ically all ofthe recoverable heat of com ustion is removed from the gases by radiation through the ducts, so that the gases, upon leaving the ducts, have a temperature so low that practically. nofurther transmission ofheat can take place fromcthe gases to the oil on account of insuflicient temperature head. However, it will be noted that these gases come in contact with the main, body 200 of the fractionating still which will'absorb a small amount of heat from the gases; suflicient at least to throw the balance on the safe side so that the main body of the still will not be radiating heat to the outside air.

This temperature, of course, rises as distillation proceeds, but the same relative conditions exist under uniform rate of evaporation. Now, in order to salvage as much of the heat remaining in the flue gases as practicable, 0. pro-heater 300 is shown adjoining the still setting at the rear. This pre-heater may be used for warming up the crude charge before it is placed into the treating still or for warming the distillate before it is placed in .either still. It may also he used for maintaining the temperature of the oil in the treatingstill in which it is being held, pending the completion of a run in the fractionating still.

In other words after the oil has been raised to a temperature of 300 F in the treating still, a outlined previously, the fires may be shut off and this temperature maintained by circulating the oil from the treating still through the pre-heater as shown in conjunction with the fractionating still.

During the pressure treating it would be, of course, hardly practicable to agitate the oil and treating solution by means of air or steam because of the fact that the treating is carried on under pressure. Therefore the oil would be agitated by means of pump circulation as stated, using pump A ,which would take oil from one end of the still and discharge it near or at the opposite end, thus circulating the oil within the still and thoroughly mixing the oil and treating solution.

As will be noted, the space above the tubes and the tube spaces at either end of the tile 'areopen so that a certain amount of circulat-.

ing takes place more or less parallel with the tubes, due to temperature.

It is to be understood that my process may be practiced with plants, appliances and apparatus which may differ widely from that described herein. It is also to be understood that as many changes could be made in the above constructional features and process and manywidelydifi'erent embodiments of this invention could be made without departing from the scope thereof, it is "intended that all 'matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. i

What I claim is i 1. In the art of heating oil the steps of heating heat transmitting material by the combustion of fuel and thereby lowering the temperature of the direct products of combustion, and simultaneously withdrawing heat units from said material by contacting a current of relatively cool gas with said material but out of contact with the direct products of combustion, whereby two se arate quantities of heated gas are obtained but both at temperatures substantially below the com material and the temperature of such gases is reduced, causing such gases to deliver remaining heat units to the material to be heated, passing a gas in contact with said heat absorbent material but out of contactwith said fresh products of combustion, whereby heat units are transmitted from said heat absorbent material to said gas, passing said gas in indirect contact with the material to be heated and delivering heat units from said gas to said material.

4. The process as defined in claim 3 in,

which spent products of combustion are used to withdraw heat units from said heat ab-" sorbent material after having delivered heat units to the material to be heated.

The method of heating oil which comprises generating heat by combustion, pass ing gaseous products of combustion through which the said heat absorbing surfaces of the still are positioned a substantal distance from the heat transmitting walls.

8. The method of distilling petroleum oil v without substantial cracking which comprises the steps of: generating heat by. combustion, contacting the products of combustion with one face of a heat absorbing structure whereby'the products of combustion are partly cooled, while contacting a gas with the other face of such heat absorbing structure to withdraw, heat units therefrom and calls ing such gas to contact with a container for the oil to be distilled, and transmitting other heat units from the partly cooled products of combustion to relatively small masses of the oil to be distilled which masses are in rapid movement from and back to a large mass-of such oil below the surface level thereof, and

withdrawing vapors from the surface of the large mass of oil.

This specification signed this 11th day of June, 1925,

RICHARD F. GILDEHAUS, JR.

a heat absorbent structure, partly cooling c said fresh products (if combustion by separately delivering a portion of the contained heat to the heat absorbent structure, withdrawing heat from the heat absorbent structure and transmitting such heat to the container for the material to be heated largely by convection, whereby asubstantial heat differential between the surface of such container and said heat absorbent structure is maintained, and causing the partly cooledfresh products. of combustion separatelyto deliver heat to a different portion of the still from that which is being treated by the heat withdrawn from said heat absorbent structure.

6. In combination a still having a plurality of heat absorbing surfaces, an elongated combustion chamber with walls formed of heat transmitting material adapted to absorb heat from fresh products of combustion, means for burning fuel in such chamber, means for bringing products of combustion which have given up a portion of their heat units to said walls into contact with a heat absorbing surface, of the still, and thereafter into contact with said heated walls but out of contact with fresh products of combustion, and means for thereafter bringing the reheated products of combustion into contact with another heat absorbing surface of the still.

7. A structure as specified in claim 6 in (IERTIFIGATIE 0h CORRECTION.

Patent No. E,834,6%. Granted December r, 1931, to

RICHARD h. GKLDEHAUS, JR.

M is hereby certified rhea errer appears in the printed specification of the above numbered arem requiring eerreerfieh as follows: Page 8,, line 46, claim 5, fer, rhe word "treated" read heated; and rhar thesaid Letters Patent should he read with this eorreerioh therein hm the same may conform to the record of the ease in the Parent. @Efiee.

Signed and seafiedl rhis 16th day 01? Febrhary, fa. D. 1932.

J M. J. Moore,- Acti'ng Gommissioner of Patents.

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