US2122705A - Method of vaporizing heavy liquid hydrocarbons - Google Patents

Description

y E. c. WELBORN ETAL 2,122,705

METHOD OF VAPORIZING HEAVY LIQUID HYDROCARBONS Filed Aug. 1, 1936 3 Sheets-Sheet 1 y 1933- E. c. WELBORN ET AL 2,122,705

IETHOD OF VAPORIZING HEAVY LIQUID HYDROCARBONS Filed Aug. 1, 1936 :s Sheets-Sheet 2 63 53 EdgarCWeZbOr Henry l'fimd" J4, u/W

July 5, 1938. E. c. WELBORN El AL METHOD OF VAPORIZING HEAVY LIQUID HYDROCARBONS Filed Aug. 1, 1956 5 Sheets-Sheet 5 F5168 Level Henry Q YWMZRMJEMJ Patented July 5, 1938 PATENT OFFICE METHOD OF VA PORIZING HEAVY LIQUID HYDROCARBONS Edgar C. Welborn and Henry J. Smith, Chicago, Ill., assignors to Mark C. Bates, Chicago, Ill.

Application August 1,

16 Claims.

Our invention relates in general to the vaporization of relatively heavy liquid hydrocarbons and similar substances. It concerns itself also with the utilization of the vapors, preferably pre- 6 mixed with air, in combustion devices of various types, although the invention is capable of many applications There are many conditions under which vaporization of relatively very heavy liquid hydrocarbons is desired, preferably vaporization under such conditions that the vapors may be premixed with air for complete blue flame combustion or, for example, preparatory to utilization of the combustible mixture in internal combustion engines and the like. While methods of vaporizing relatively heavy liquid hydrocarbons have been developed, such methods have had certain limitations, principally in that the range over which they could be operated has not been sufficiently great under extreme conditions, and very heavy liquid hydrocarbons could not be vaporized successfully without considerable carbon formation which required relatively frequent cleaning of the equipment employed in the process.

The object of our invention is the provision of an improved method of vaporization.

Another object is to vaporize relatively heavy liquid hydrocarbons by a method which permits a relatively wide range of operation without impairment' of the quality of vapors produced.

Another object is to vaporize relatively heavy liquid hydrocarbons with the formation of substantially no carbon.

Another object is to vaporize relatively heavy liquid hydrocarbons in such a manner that the hydrocarbon in the liquid phase is never in contact with a surface substantially hotter than the liquid.

Another object is to vaporize relatively heavy liquid hydrocarbons by a method wherein there is substantially no fixed resistance which will require variation in operating conditions as the quantity of hydrocarbon vaporized is modified. Another object is to vaporize a relatively very heavy liquid hydrocarbon by a method wherein substantially no unvaporized liquid will be entrained with the vaporized liquid.

Another object is the provision of a method whereby heavier hydrocarbons can be vaporized than have been successfully vaporized heretofore.

Still another object is the provision of apparatus whereby heavier hydrocarbons can be successfully vaporized in accordance with the principles of our invention.

In carrying out the method, the liquid hydro- 1936, Serial No. 93,782

carbon is moved in the form'of a relatively thin film over a relatively cool surface which is entirely covered with the liquid hydrocarbon, and hot inert products of substantially complete combustion are passed in contact with the film of liquid hydrocarbon in a direction opposite to the direction of movement of said film. More specifically, the liquid hydrocarbon is continuously delivered through the top of a fountain, the amount delivered through the fountain being such that the outer surface of the fountain is completely wetted with the liquid hydrocarbon at all times. The excess unvaporized liquid hydrocarbon flows from the bottom of the fountain into a pool of oil which is again delivered to the fountain through a recirculating system. Hot inert products of complete combustion are delivered to the chamber containing the fountains in such a manner that the hot products of combustion pass upwardly over the exterior surface of the fountains and extract vapors from the surface of the liquid hydrocarbon on the fountain wall. The mixture of hot inert products of combustion and the vaporized liquid hydrocarbon are drawn out of the vaporization chamber, preferably superheated to some extent either in the vaporization chamber or on the way to a manifold. The hot vapors. may be mixed with air suflicient for complete combustion immediately after withdrawal from the vaporization chamber, or they may be mixed with air at a combustion device, the former method being preferred for most purposes. A portion of the combustible mixture may be burned in a pilot burner, producing a blue flame, and the hot products of such blue flame delivered to the vaporization chamber for c0ntact with the surface of the liquid hydrocarbon. The inert gases utilized for vaporization, however, may be drawn from a separate source, if desired. Other details and features will be apparent from the detailed description taken with the accompanying drawings, wherein Fig. 1 is a vertical sectional view, partly in elevation, showing one embodiment of the vaporizing mechanism of our invention;

Fig. 2 is a plan view, partly in section;

Fig. 3 is a sectional view taken on the line 33 of Fig. 1, looking in the direction of the arrows;

Fig. 4 is a fragmentary. sectional view, partly in elevation, showing a fuel level control device;

Fig. 5 is a fragmentary vertical section illustrating structural features of one form of fountain;

Fig. 6 is a view similar to Fig. 5 showing a modified form of fountain heads;

20 throat |6 to a mixing chamber ted to the mixing chamber through an air pas- 40 a pilot burner 28.

Fig. '7 is a fragmentary vertical sectional view showing the principles of our present invention employed with modified means for creating a pressure diiferentiai for the purpose of with- 5' drawing vapors from a vaporization chamber;

and

Fig. 8 is a vertical sectional view showing a modified fountain type of device utilizing the features of the present invention.

10 Referring now to the drawings, we provide a vaporization chamber l0 within which are supported a plurality of fountains adapted, in a manner to be described, to be wetted at all times with the liquid to be vaporized. Apool of hot oil I2 is maintained in the vaporization chamber by level control device |3 which may, for example, .be an ordinary type of float valve. The vaporization chamber is provided with an upper extension |4 connected through a communicating Air is admitsageway l8, air control means l9 being provided to adjust the quantity of air admitted. A quality damper is provided within the throat l6 for controlling the amount of vapors delivered from the vaporization chamber to the mixing chamber IT. The mixing chamber communicates with a blower housing 22, an impeller 23 being operated by the motor 24 to withdraw vaporous products from the mixing chamber l1 and deliver the same under pressure to a manifold 25 The blower also furnishes the powerfor drawing the air and vaporous products into the mixing chamber from the air passageway and vaporization chamber respectively.

45 the vaporization chamber and delivers hot products of combustion to the bottom of the vaporization chamber. In the form of device shown, an oven 32 surrounds the extension of the vaporization chamber, the mixing chamber, the air in-- so take, and the blower, to maintain these parts in a heated condition whereby to secure certain advantages, some of which are apparent and others of which will be pointed out subsequently. Ports 33 are provided in the combustion tube 29 for de- 155 livering some of the hot inert products of combustion into the oven, whereby to heat the parts contained in the oven and superheat the combustible mixture, without however raising the temperature sufficiently to cause its ignition or 60 thermal decomposition of the fuel vapor.

The fountains II have a hollow interior and are specially constructed to deliver the liquid tobe vaporized to the top thereof and to secure other advantages which will be pointed out.

65: These fountains are supported in the bottom of the vaporization chamber and communicate with a lower chamber 36 having a downward extension 31. The lower part of the vaporization chamber is provided with an opening communi- 70 eating with a pipe 38. A pump 39 has its intake and exhaust ports so arranged as to withdraw liquid from the vaporization chamber through the pipe 38 and deliver the same through a pipe 4| to the extension 3'| of the chamber 36. By

75 this means, liquid is continuously withdrawn from the bottom of the vaporization chamber anddelivered through the chamber 36 to the fountains II with Just enough pressure to sustain' the desired rate of flow. The liquid flows down the outside of the fountains and excess liquid not vaporized returns again to the pool |2 in the bottom of the vaporization chamber. The pipe 38 extends through the extension 31 and is provided with a port communicating with the extension 31. A valve 2, threaded in a boss provided on the extension of the chamber 36, is adjustable to regulate the opening in the inner communicating port whereby some of the liquid can be hy-passed and the amount delivered to the fountains may be regulated.

We also provide an additional by-pass for the liquid through a heating chamber 43, a pipe 44 interconnecting the heating chamber 43 and the intake side of the pump, and a pipe 46interconnecting the opposite side of the heating chamber and the pressure side of the pump. A valve 41' is positioned in the pipe 46 to regulate by-pass of the liquid through the heater 43, whereby the liquid oil temperature may be automatically controlled.

According to one form, as illustrated in Fig. 5

the fountain I comprises an outer pipe 48 preferably having a roughened exterior. One very advantageous method of treating the exterior is to provide continuous threads 49 running the full length of the pipe. Within the relatively larger pipe 413 is a smaller pipe 5| which carries the liquid to the top of the fountain. The pipe 5| is secured in the bottom of the pipe 48 such a manner that liquid is permitted. to enter the pipe 5|, but prevented from entering the annular space between the two pipes by reason of the air filling the space between the two pipes. The air space acts as a cushion and serves to equalize the flow of oil to the fountain head. At the top, the pipe 5| is threaded into a plug 52. The plug 52 is open at the top to permit communication with a specially designed ring 53, which is capped with a cup-shaped member 54 which sets within the top of pipe 48 and is spaced therefrom so as to leave a relatively narrow annulus 56. One port 51 is provided in the cup-shaped member 54 and communicates with theinside of the ring member 53, Ports 58 in the ring member 53 communicate with the space above the plug 52 and between the cup-shaped member 54 and the upper inside surface of the pipe 48.

As a result of this construction, the major portion of the liquid delivered through pipe 5| passes out through ports 58, flows through the annulus 56, and down the outside of pipe 48. A portion of the liquid, however, is delivered through port 51 into the inside of cup 54, maintaining this cup full and slightly overflowing at all times, whereby all of the surfaces at the top of the fountain are kept wet. The separation of the pipe 5| prevents the incoming oii from having a cooling effect on a film of oil flowing down the outside of pipe 48.

In the simplified form of device shown in Fig. 6, an outside pipe 6| of the fountain is of smaller diameter than the pipe 48 shown in Fig. 5, but otherwise has the same characteristics and is mounted in the same way in the vaporization chamber. An internal pipe 62 is separated irom the inside of pipe GI and is threaded into a plug 63 secured near the top of pipe 6|. Theplu'g 63 is provided with a port 64 forming a communication between the inside of pipe 62 and the Git also, the annular space between the two pipes preferably is maintained empty. Liquid delivered through pipe 62 fills the upper portion of pipe GI and flows down the outside thereof. Due to the relatively small diameter of pipe ii, the surface tension of the liquid causes it to take a convex form slightly above the top of the pipe and to flow uniformly over the entire upper annulus. It is unnecessary, therefore, to take the same precautions to maintain all of the upper surfaces in a wet condition.

In Fig. 4, special means visprovidted for maintaining the level of the liquid hydrocarbon in the bottom of the vaporization chamber. A fuel level chamber 66 is provided, through the bottom of which an overflow pipe 61 is threaded, this overflow pipe preferably having an enlarged intake 68. The overflow pipe discharges into-a trap 69. A fuel level pump 1| withdraws oil from a container (not shown) through pipe 12 and delivers the oil through pipe I3 to the fuel level chamber 66. A pipe 14 connected to the trap 69 near the top thereof delivers overflow oil back into the container for the fresh oil supply. A balance line 15 forms a communication between the chamber 66 and the vaporization chamber to equalize pressures and facilitate free functioning of the level control apparatus. By this means, a constant fuel level is maintained without the use of float valves and similar devices which might readily get out of adjustment when submitted to the relatively rough usage in a plant to which equipment of the kind described is often exposed.

It is believed that the method utilized in the vaporization of the liquid hydrocarbon is in general clear from the preceding description. In order to permit those skilled in the art, however, to adapt the method to modified apparatus, if desired, the method, features of the invention, and modifications thereof will be described more in detail.

The vaporization medium employed is a hot inert gas, such as products of complete combustion. It has been found that when a relatively heavy liquid hydrocarbon is vaporized by means of hot gases, and out of contact with surfaces which may cause cracking, carboniza- The combustion products so produced, therefore,

are substantially inert, particularly when allowed to cool to 1600 degrees F. or below-that is to say, if allowed to cool to temperatures where dissociated CO2 and H20 are reduced to a minimum. The resulting hot inert gases are utilizable for vaporization purposes and, when employed according to the present invention'and by a method wherein an excess of a liquid hydrocarbon is always present, will produce a very satisfactory vaporized product.

The fuel product to the vaporization of which the present invention is particularly directed is a relatively heavy liquid hydrocarbon, that is, one heavier than kerosene or having a Baum gravity of 40 or less. Other vaporizable liquids, however, may be vaporized by the apparatus with which the method is practiced.

In the operation of the apparatus shown in Fig. 1, hot oil is withdrawn from the bottom of of 011 being sufficient so that the outside surface of the fountains is wetted by the oil to the very bottom thereof. All exposed surfaces, therefore, are wet at all times. It has been found that any part which is not constantly covered with the hot oil in the process will be quickly coated with considerable quantities of carbon or coke. The roughened exterior surface, particularly when in the form of a continuous thread, improves the distribution around the fountain tube and also creates sufllcient resistance against gravitational force so that the oil film does not get too thin at the base of the fountain where it is subjected to the highest temperature. This arrangement is particularly desirable when the temperature of the incoming vaporizing gases is relatively high and the viscosity of the oil is correspondingly reduced so as to flow more freely than usual.

.It will be noted that the construction of both fountains illustrated in Figs. 5 and 6 is such as to cut down the speed of flow at the fountain head and thus avoid splashing or spraying of the oil which would have the effect of projecting particles of oil out into the path of the hot gases instead of depositing it on the outside fountain tube. According to the form shown in Fig. 5, the cup 54 is filled with oil through the orifice 51 to overflowing, and the oil overflowing from cup 54 so mingles with the oil passing upwardly through the annulus 56 that a smooth even flow takes place around and over the upper edge of pipe 48. In the form shown in Fig. 6, the discharge from the smaller pipe 62 is sufficiently below the top of pipe 6| so that a relatively slow moving body of oil is provided at the top, which spills over the edge uniformly slowly and in an annularly shaped stream.

The hot gases delivered to the bottom of the vaporization chamber through the extension 3| of the combustion tube strike the upper surface of the pool of oil I2 and then flow upwardly around the plurality of fountains. While unquestionably there is some vaporization from the surface of the pool of oil, the greater portion of the vaporization takes place when the gases come in contact with the film of oil on the fountains, because the surface is so much greater and the duration of contact is also much longer. The counter-flow principle results in the gases, when in the hottest condition, coming in contact with oil more difficultly vaporizable because of the previous'removal of relatively lighter fractions; while at the higher portions of the fountains. when the hot gases have already been cooled somewhat, the lighter, more readily vaporizable fractions can still be removed. The maximum area of the fountains over which vaporization takes place is determined in large part by the amount of hot gases delivered to the vaporization chamber, particularly if the hot gases are always -of the same temperaturejwhich is the desired method of operation. The maintaining of more area than is necessary assures satisfactory operation, even when maximum demands are made on the equipment and assures a constant quality vapor at extremely low and extremely high outputs.

When operating the specific device shown, the blower withdraws vapors from the vaporization chamber (mixed with hot gases) and also withdraws ;air through the air intake I 8. Both the vapor and air intake valves are adjustable automatically by suitable means such as shown, for example, in the copending application of Clyde B. Faverty, Serial No. 710,971, filed February 12, 1934. The air and vapor mixed in the mixing chamber I l are drawn into the blower where they are further mixed by the action'of the impeller, and are thence delivered under pressure to manifold 25. A portion of these vapors, as noted, is withdrawn from the manifold, burned in the pilot burner, and the hot. products of combustion of the pilot burner delivered back through the combustion tube into the vaporization chamber.

As the oil is vaporized, additional oil is delivered to the vaporization chamber, where it mixes with the hot oil already contained therein, and this mixture is continuously withdrawn from the vaporization chamber and fed back to the fountains.

For convenience, the embodiment shown in Fig. 1 is illustrated as being operated on the suction principle, as described in the copending application identified hereinabove. It should be understood, however, that when the vapors are to be mixed with air and delivered to a combustion device, it is only necessary that a pressure differential exist sufiicient to cause the mixing action and deliver the premixed products of combustion to a point of use. If desired, for example, the novel features of our invention may be utilized in carrying out'the method described in the copending application of Charles A. French, Serial No, 47,910, filed November 1, 1935, and, in general, the equipment disclosed by French for withdrawing vapors from the vaporization chamber and mixing the same with air may be utilized.

The equipment shown in Fig. 1 or other embodiments of the invention utilizing substantially the same principles may be started in a number of ways. According to one method, oil may be delivered to the vaporization chamber .and circulated through'the heater 43, or heated by other suitable means, until it reaches a temperature where sufiicient vaporization occurs to start the pilot burner; thereafter the equipment can be run in the usual manner, although some short time may be required before vaporization has progressed to a point where the vapors can be burned satisfactorily in a combustion device. Another method is initially to substitute or mix a small quantity of gasoline or other highly volatile fuel with the oil and immediately start operations, utilizing vapors from the readily vaporizable gasoline constituent. As the unit comes up to temperature, the gasoline supply may be gradually reduced until it is finally cut off entirely, vaporization then being continued on the regular oil. Still other methods of starting may be employed which it seems unnecessary to detail. One of the simplest methods of starting is to burn a commercial gas flame or hold a torch so that the hot products of combustion enter the downcomer. vaporization may be started very quickly and, as vaporis generated, the gas flame or torch may be extinguished.

One advantage of the present method of vaporization is that the amount of oil delivered either through the fountains or to the vaporization chamber during any given period is not critical. For example, more oil is delivered through the fountains than can be vaporized at any one time and, even if the amount delivered.

were increased or decreased considerably from the calculated amount, vaporization would still continue without difficulty. In addition, the fuel level maintained by the fuel level control system is not critical. For example, the height of the liquid in the vaporization chamber might, through faulty operation of the fuel level maintaining mechanism, be raised or lowered considerably and it would not prevent satisfactory operation.

The embodiments of the invention hereinabove described utilize the suction principle for promoting flow of vapors from the vaporization chamber into the mixing chamber, and a'fiow of the resulting combustible mixture into the manifold. Any means for producing such a pressure differential in parts of the apparatus employed so as to cause this identified flow of vapors, air and mixture thereof to the manifold, and wherein the pressure within the manifold is sufliciently great to cause a flow of the mixture from the manifold to combustion apparatus may be utilized. For a further understanding of the application of our present invention to further modifications in apparatus, we illustrate in Figure 7 a form of the invention wherein movement of the gases and vapors is caused primarily by incoming air pressure from air pressure apparatus such as a conventional rotary type of blower (not shown).

Referring now to Figure 7, the embodiment there illustrated comprises a vaporization chamber I6 carrying a plurality of fountains ll similar in general structure to the fountains previously described. A constant level offuel to be vaporized 78 is maintained in the vaporization chamber by means of suitable level control apparatus 19 which may be a float operated mechanism if desired. A pipe 8i leads from the level control apparatus 19 to a fuel supply tank. The vaporization chamber has a bottom 82 in which the fountains are secured and through which the interior of the fountains communicate with a bottom chamber 83. Oil is withdrawn from the supply 18 through a pipe 8& being pumped therefrom by a pump 86 and delivered back under pressure through a pipe 81 to the chamber 83 whence the fuel oil is delivered to the top of the fountains H and 'flows down the sides thereof in the manner previously described.

The vaporization chamber has a top extension 8i! communicating through a throat 89 with 'a Venturi tube 91. Air under pressure is delivered to the Venturi tube through a forcing nozzle 92 whereby to withdraw vapors through the throat 89 and mix the same with air to form a combustible mixture, which combustible mixture is delivered to a manifold 93.

A robber tube 94 is set in a manifold or at a suitable place in the path of the combustible mixture to withdraw such combustible mixture and deliver the same to a pilot burner 96. The robber tube is connected to a T 91, one remaining arm of which is connected to deliver combustible mixture to the pilot burner 96 and the other of which is connected to a pipe 98 supplied with a valve 99. Under suitable conditions, if desired, additional air may be admitted through pipe 98, or if desired in starting the apparatus the pipe 98 may be connected to a commercial gas line to initiate combustion at the pilot burner. The pilot burner delivers hot products of combustion to a downcomer tube I01 whichIextends to the lower part of the vaporization chamber, terminating a sufficient distance above the level of fuel oil in the vaporization chamber to avoid splashing thereof onto the downcomer tube. The downcomer, however, should be brought down to a low enough position in the vaporization chamber whereby to cause hot products of combustion to sweep upwardly over as much of the area of the fountains as is conveniently possible within the limitations of ordinary design. I

The operation, functions and advantages of the embodiment shown in Figure '7 are in general substantially the same as those described in connection with the previous figures. The movement of hot products of combustion is counter to the flow of fuel oil down the outside of the fountains. The productsof combustion in this form of the invention are also substantially inert and the efliciency in the vaporization of the fuel oil as well as'the elimination of carbon is very marked. In this form of the invention a salient difference is that air under relatively high pressure is employed in place of an ordinary type of suction fan which requires less power input particularly under certain operating conditions. While the embodiment of Figure '7 is not capable of the extremely low turndown. which is possible when utilizing, for example, the embodiment shown in Figure 1, there are instances where for other reasons, unnecessary to detail, the form of Figure 7 may be preferred.

Figure 8 shows a modified form of device which may be termed a fountain wherein the liquid hydrocarbon is flowed over a surface which is maintained in a wet condition at all times, and hot gases are passed over the surface of oil in a direction counter to the direction of movement of the oil. In this form of device, obviously, either the suction type of blower, as illustrated in Figure 1, may be employed, or the blast type as illustrated more particularly in Figure 7. This will be made clearer, however, from a specific discussion of the embodimentof Figure 8.

A vaporization chamber I06 is provided of substantially the same character and construction as the vaporization chamber described in connection with preceding embodiments. The vaporization chamber has an upper extension I0I through which hot vaporous products are deliv.

ered to a manifold (not shown). Within the vaporization chamber is a cup-shaped member I08 spaced from the side walls and bottom of the vaporization chamber to provide a space for liquid hydrocarbon I09. The spaced relation between the cup-shaped member I08 and the inner wall of the vaporization chamber I06 is maintained by a flange I I I, provided with apertures I I2 through which liquid hydrocarbon is adapted to pass. A pump I I3 is provided which withdraws liquid, hydrocarbon through a passageway H4 from the bottom of the vaporization chamber and delivers the same through a passageway II6 to the space between the wall of the vaporization chamber and the cup-shaped member I08. A pool of oil is maintained in the bottom of" the vaporization chamber at constant level by a levelling device indicated generally by the reference :haracter 1, fresh oil being delivered to the vaporization chamber through a pipe I I8 and to the level maintaining device from a fuel tank (not shown) through a pipe H9. The usual balance line I2I is also provided. A pilot burner I22 fires into a downcomer I23 extending into the vaporization chamber and having an extension I24 which may be provided with a bell shaped skirt I26 near its lower end.

In the operation of the form of device illustrated in Figure 8, oil is continuously withdrawn from the bottom of the vaporization chamber and delivered to the outside of the cup-shaped member I08. The oil so delivered spills over the upper annular edge of the cup-shaped member and flows down the inner wall thereof which is preferably provided with a roughened interior, for example, by being provided with inner threads. The amount of oil delivered is such that the inner surface of the cup-shaped member is wet at all times. The hot products of combustion from the pilot burner are delivered to the bottom portion of the vaporization chamber, whence they pass upwardly along the surface of the oil and vaporize a portion thereof. The vaporous mixture is then delivered to a mixing chamber either of the general type illustrated in Fig. 1 or of the general type illustrated in Fig. 'I. It is, of course, obvious that the specific treatment applied to the vaporous products after they leave the vaporization chamber depends to a considerable extent upon conditions, the type of installation, the character of the combustion device, etc. The skirt I26 is by no means necessary, but it serves the function of bringing the hot gases into more intimate contact with the 011 film, and also of preventing too great an application of radiant heat to the 011 while in a liquid condition.

It should be understood that in all of the embodiments of the present invention the construction, shape, position and other characteristics of the fountains may be modified considerably without departing from the spirit and scope of the invention. An important feature is the counter flow of the hot products of combustion of the fuel oil with the results and advantages detailed throughout a previous portion of the specification.

Some of the features of our present invention, particularly with respect to the lack of carbon formation and efliciency in the vaporization of relatively heavy liquid hydrocarbons may be pointed out for the benefit of those skilled in the art.

The invention has its inception largely in the discovery that by employing hot products of combustion in combination with an excess of liquid fuel, a vaporous mixture may be produced which is readily combinable with air in proportions capable of producing complete combustion in the form of a blue flame so that even under practically operable conditions the hot products of such blue flame comprise substantially only carbon dioxide, water and nitrogen, disregarding negligible proportions of rare gases found in the air and relatively very small amounts of organic and sulphurous materials calculated to be present but not detectable by the usual analytical methods.

Such products of combustion being substan tially inert will not produce carbon, sludge, and the like, when they are, while in a hot condition, brought into contact with the heavy liquid oil, and this may be compared to the deleterious results which follow if hot chemically active gases should be brought in contact with the liquid fuel oil. While it is known that at extremely high temperatures even gases like H2O vapor and C0: are dissociated and therefore contain active C0, 02 and H2 constituents, we prefer to bring the hot products into contact with the oil at a temperature not substantially higher than 1600 degrees F., that is, essentially below the temperature of dissociation of the products of combustion so that the hot gases are truly inert from every standpoint.

Another feature is that the liquid fuel is at all times prevented from coming into contact with metal surfaces at temperatures substantially higher than the temperature 01 the liquid oil,

although the fuel vapors may be permitted to and do come into contact with hot surfaces but this jcontactgis by no means detrimental but actually fintroduces superheat and substantially inhibits condensation. Anotherfeature that liquid fuel particles are not entrained in the hot gas and 0 vapor flow, but substantially the only oil leav-, ing the surface of thefliquid is substantially of 7 molecular proportions. 77 g Our invention has been described in detail to teach those skilled in the art how to practice the f same. L We do not limit ourselves, however, to the details of our invention except within the scope of the appended claims. 2

c What we claim as new and desire to protect by Letters Patent of the Cinited States is:

1. Inan oil yaporizer', a vaporization chamber, a plurality of fpuntainsdisposed vertically in said vaporization chamber, means for delivering oil to the tops of each of said fountains in quantity sufficient to how down the outside of said fountains and maintain a coating of oil'on every portion thereof atflall times, means for withdrawing vapors -from the vaporization chamber, means for mixing said vapors with air sufiicient for complete combustion, means for burning at least a portion of saidfi mixture, and means for delivering hot products combustion resulting from said burning to the vaporization chamber at the lower portion of said fountains. i

2. A vaporizer as defined in claim l lincluding means for maintaining a body of oil in the vaporization chamber, and means for withdrawing a portion of said oil and delivering the same to said fountains.

3. A vaporizer as defined in claim lincluding, in combination therewith, means for superheating said vapors arid air mixed therewith prior to cornbustidn thereof thereby inhibiting recondensation of the vapors. W e f 4. In an oiigvaporizer, a vaporization chamber, an oil chamber immediately below said vaporization chamber, means for mahfitainingia body of oil in the vaporization chamber, a generally cylindrical fountain having a hollow interior secured in the bottom of the vaporization chamber and communijeating with said oil chamber, means for withdrawing oil from the vaporization chat. her and delivering the same under pressure'to said oil chamber whereby to force oil to the upper part of said fountain and cause the same to fiow down the outside surface thereof in sufficient amount to maintain said surface wet with oil at all times, and means' for passing a hot inert gas over the outside surface of said fountain whereby to vaporize oil from the surface thereof.

5. A vaporizer as defined in claim 4, including means for withdrawing vapors from the vaporization chamber, means for mixing said'jvapors with air, and means for burning a portion such mixture, hot inert products of combustion resulting from said burning being utilized as a gas for vaporizing oil from thfsurface of said fountain.

6. A vaporizer as "defined in claim 4 wherein a plurality of fountains is utilized, and hot products of combustion are passed over said plurality of fountains in a direction counter to the direction of flow of said oil.

7. 'A fountain adapted for utilizatibn in an oil vaporizer comprising a tubular member having a roughened exterior surface; a pipe within said tubular member terminating short of the upper end thereof and'spaced from the inner wall of the tubui ar member for delivering oil to the top thereof, and means for causing the oil to flow smoothly over the top of the tubular member whereby to avoid splashingfiand to promote a smooth, even flow of oil along the outer surface of the tubular member.

8. A fountain as defined in claim 7 wherein said last mentioned means comprises a cup-shaped member having a rim spaced 2. short distance away? from the tubular member so as to leave an annular opening at the very top thereof, and passageways communicating with said pipe for delivering a major portion of the oil through said annular opening, and a miner proportion of the oil to, the exterior of said cup-shaped member.

9. A fountain as defined in elaim 7 wherein the outer surface of said tubular member is provided with a relatively coarse thread whereby to control the flow of oil down the outside thereof,

16, In anoil vaporizer, a vaporization chamberfa generally cup-shaped member having, an inner wall, said cup-shaped member being spaced from the vaporization chamber so as to leave a generally annular space atgthe outside thereof, means for delivering oil to said annular space so as to flow the same down the said inner wall, and means for passing hot gases over the face of the oil as it flows down said inner wall. 3

1;. A method of providing a; combustible mixture of air and a vapor of a fuel oil heavier than kerosene which comprises maintaining a pool of fuel oil in the lower part of a vaporization chamber, pumping liquid fuel oil from said pool to the upper part of a surface disposed within said vaporization chamber and causing said liquid fuel to flow downwardly in a relatively thin film over said surface so as to maintain a coating of oil at all tiines on said surface, unvaporized liquid excess fuel being returned to said pool, introducing hot substantially inert products of combustion into the lower partof said yaporization chamber and causing said hot products of combustion to pass upwardly along and in directcontact with the downwardly fipwing film of liquid fuel oil whereby oil vaporsiare withdrawn therefrom and pass to thegupper part of said vaporization chamber, commingling air with said oil vapors toq'form a combustible mixture, burning a portion of said combustible mixture to form hot substantially inert products of combustion, and utilizing the latter to vaporize additional quantities of liquid oil from the downwardly flowing film, said exterior surface being substantially unheated, except for that heat which is conducted thereto by the fuel oii flowing into direct contact therewith.

12. A method of vaporizing a fuel oil substantially heavier than kerosene which comprises provi'zling an extended generally vertical exterior surface within a chamber, flowing the fuel oil to be vaporized downwardly on said exterior'surface and in amounts sufiicient to maintain aooating of oil at all times on said entire exterior surface and passing" a hot substantially inert gas upwardly of said exterior surface and in contact a with said downwardly flowing, fuel oil whereby vapors are withdrawn from said fuel oil, the hot siibstantially inert gas providing essentially the sole means for vaporizing the fuel oil and the said exterior surface being substantially unheated except for that heat which is conducted thereto by the fuel oil flowing downwardly thereof.

13. A method :of vaporizing a relatively heavyfuel oil which comprises maintaining a pool of oil in the lower part of a vaporization chamber.

delivering oil from said pool to the top of a fountain disposed within said vaporization chamber and causing said oil to flow downwardly on the exterior surface of said fountain in amount sufflcient to maintain a coating of oil on all parts of said exterior surface whereby excess oil continuously flows back into said pool of oil, passing a hot substantially inert gas upwardly of said exterior surface and in contact with said downwardly flowing fuel oil whereby vapors are withdrawn from said fuel oil, the hot substantially inert gas providing essentially the sole means for vaporizing the fuel oil and the said exterior surface being substantially unheated except for that heat which is conducted thereto by the fuel oil flowing into direct contact therewith.

14. In an oil vaporizer, a vaporization chamber, means therein providing an extended exterior surface whereby liquid oil may be flowed downwardly thereon, the lower end of said means being located in the lower part of said'vaporization chamber, a pipe generally vertically disposed within said vaporization chamber and the lower end of which pipe opens near the bottom of said vaporization chamber, said pipe being spaced from the first-mentioned means, and means for generating and delivering hot substantially inert products of combustion into said pipe whereby said hot products of combustion emerge into the lower part of said vaporization chamber and then pass upwardly and in direct contact with the downwardly flowing liquid oil whereby oil vapors are withdrawn therefrom.

15. In an oil vaporizer, a vaporization chamber, at least one fountain disposed generally vertically within said vaporization chamber, means for delivering oil to the top of said fountain in quantity sufficient to flow downwardly on a surface of said fountain and maintain a coating of oil on all parts of said surface, a generally vertically disposed pipe which enters through an upper part of said vaporization chamber and is spaced from said fountain and discharges at a point near the bottom thereof, and means for delivering hot substantially inert products of combustion into said pipe whereby said hot products of combustion emerge into the lower part of said vaporization chamber and then pass upwardly and in direct contact with the downwardly flowing liquid oil whereby oil vapors are withdrawn therefrom.

16. The structure defined in claim 15, including means to mix the oil vapors with air in the upper part of said vaporization chamber to produce a combustible mixture, means to withdraw said combustible mixture, and means to burn the same, the resulting hot substantially inert gases being conveyed to said pipe.

EDGAR C. WELBORN. HENRY J. SMITH.

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