US1853753A - Process for treating hydrocarbon oils - Google Patents

Description

April 12, 1932. c. Fe. WAGNER PROCESS FOR TREATING HYDROCARBON OILS Filed June 1l, 1928 abtoz Ms.

Patented Apr. 12, 1932 UNITED STATES PATENT oFFlcE CARY R. WAGNER, 0F CHICAGO, ILLINOIS, ASSIGNOR TO THE PURE OIL COMPANY, OF

GHICAGO, ILLINOIS, A CORPORATION OF OHIO l PROCESS VEOIR, TREATING IYDROCARBON OILS Appia-ation mea :une 11, 192s. serial No. 284,306.

whereby such lower boiling point hydrocar-v bons are rendered suitable for use as a motor fuel. The process, however, in certain'of its aspects is not limited to the particular use mentioned, as certain steps of the process have more general application.

Among the objects of the invention are To provide an improved process for treating hydrocarbon-oils so that molecular decomposition of the oils under treatment takes place when such oils are in substantially the vapor phase; to provide a process wherein the deposit of free carbon in the heating elements in vapor conducting passages of the apparatus used by the process is reduced to a minimum, to the end of providing a continuously operating system which may be operated without loss due to plant shut down and other causes; to provide a process including a converter provided with a plurality of tubular heating elementsthrough which the oil vapors under heat treatment are passed, and wherein such tubular heating elements are of such form and arrangement that the oil vapor as it is introduced into said converter heating elements has the temperature thereof elevated sharply to the end of producing teinperatures in the oil vapor above-1000 F., above which temperature the liberation of free carbon is substantially precluded; the provision of means causing the vapors to travel lin a thin-annular stream through the converter elements in order that heat may be more effectively applied tothe oil vapor by heating a body of such vapors both fromthe outside and inside thereof, thereby to obtain the desired instantaneous rise in the temperature of the oil vapor as aforesaid; in the provision of meansfor regulating the uniformity of volume of vapor flowing through 4 each of the tubular elements of the converter and, in general, to provide an improved process for treating hydrocarbon lls under converting conditions while such o1ls are 1n the vapor phase. .v

The present invention further provides a converter provided with a bank of tubular heating elements through which the oil vapors are circulated and heated to a temperature in excess of 1000o F. To facilitate the rapid elevation of the temperatures of the vapors, for example, from approximately 650 to over 1000 F., there is placed in the oil vapor entering row of tubular heating elements a plurality of .secondary tubes, which vare interposed concentrically within the outer or primary tubes, and through which secondary tubes aheating medium is passed, such as superheated steam, furnace gases or thev like. The object bf such an arrangement of the tubes is to cause the oil vapor to flow therethrough in the form of a tubular or` annular stream and to permit the heat to be applied directly to .both the inner and outer sides of this vapor stream, producing eicient heat exchange so that the desired rapid rise inthe temperature of the vapors is provided.

For a further understanding of the invention reference is to be had to the following description and the accompanyingdrawings wherein:

l Figure 1 is an elevation of the apparatus including a vertical sectional view taken through an oil heater or converter formed in accordance with the present invention,

Figure 2 is an lenlarged vertical sectional view taken through the tube bank,

Figure 3 is a transverse sectional view on the lane indicated by the line 3-3 of Fig- 35 ure Figure 4 is a sectional view showing a slightly modied form of the invention.

Referring more particularly to the accompanying an oil eater or converter of the type enaployed in connection with the process comprising the present invention. The heater is formed to include the customary setting 2' in which is positioned a vertically and transversely disposed bridge wall 3, the latter serving to divide the interior of the setting into burner and tube compartments 4 and 5 respec-v tively.

drawings the numeral 1 designates 90 Supported lby the walls ofthe setting 2, and

also by the bridge wall 3 are a plurality of converting tubes 6, which are arranged in rows with the upper row of the tubes, ordinarily known as the inlet pass, indicated at B. This row of tubes is arranged to pass through the front and rear walls of the setting as well as the spaced double walls comprising the bridge 3. This upper row of tubes is connected at its discharge end by means of return bends or headers 7 with the next lower row or pass of tubes, and this latter row of tubes, as well as the remaining rows, below the row B, are supported by the bridge wall 3 and the rear wall of the setting 2. Oil vapor, obtained from any suitable pre-treating apparatus, and of a temperature of between 600 to 700 F., is introduced in the inlet pass B of the tube bank and is circulated through the tubular heating elements thereof so that the temperature of the oil vapor before leaving the converter will be in excess of 10000 F. Upon leaving the converter the oil vapors are brought into contact with a fresh body of sprayed or jetted cold oil so` that the temperature of the oil vapors will be immediately lowered in a substantially instantaneous manner below 600o F. This results in abruptly checking cracking reactions in the oil vapor and also minimizes or prevents the liberation of free carbon during the cooling operation. Following the cooling of the vapors to a temperature below 600o F. said vapors may then be further treated to steps of fractional separation to secure products of desired specifications.

While very effective results have been obtained in the matter of preventing carbon deposit following the converter by the method of spraying or jetting cold oil into contact with the heated oil vapors, some difliculty has been encountered in obtaining equivalent results at the inlet end of the converter. In many respects it is justas important in the matter of minimizing carbon deposition to.v

suddenly raise the temperature of the oil vapors from 650 to 1000o F. at the inlet side of the converter as it is to suddenly and abruptly lower the temperature, for similar reasons, at the outlet side of said converter.

In the attainment of this end I have located the entrance portion of the converter tubes B in the burner compartment 4 of the converter so that this entrance portion will be subjected to the action of the radiant heat developed within the burner compartment and in practice it has been found a considerable improvement over the former method of placing all the converter tubes in the tube compartment 5. In this compartment the tubes receive heat mainly by convection, and consequently the rate of heat transfer is not as high as when said tubes are subjected directly to the radiant component of the heat developed within the burner compartmentI 4 by combustion from the burner 8.

To more rapidly effect the rise in the tem- -perature of the incoming oil vapors as the llatter enter'the converter, the row of tubes B, constituting the inlet passyare in this instance provided with inner concentrically arranged tubes 9, which may or may not extend the full length of the inlet pass. |The entrance portions of the tubes 9, as indicated at l0, draw heated' gases from the top of the burner compartment 4 and these gases, at relatively high temperature, circulate through the inner tubes 9. After circulating completely throughthe inner tubes the gases pass to the inlet side of a fan l1 which communicates with an exhaust 12. There are, of course, other ways of heating the inner tubes such, for example, as by passing superheated steam or other gases therethrough and I therefore do not limit myself to the speciic method of introducing heat into the tubes 9 as illustrated in the drawings.

The tubes 9 may be placed in one or more of the rows or passes of the tube bank 6 or in fact may be placed in all of such passes or rows, but I have found it advisable to merely place the tubes in the entrance row as it is in this pass of tubes that the greatest benelit is obtained from the heat applied. As previously stated it is desirable to effect an instantaneous rise in temperature of the oil vapors as the latter enter the converter, and I have found that by subjecting the oil vapors lirst to the action of the radiant heat applied from the exterior of the tubes B and in then supplementing this by means of the inner heat conveying tubes 9 that a very effective yet simple construction is provided to obtain the sharp rise in temperature in the shortest time period practically possible. The oil vapor travelling through the entrance pass B is in the form of an annular or tubular stream which readily becomes heated to the desired degree by both the interior and exterior application of heat. In addition to this the vapors are more uniformly heated avoiding particularly overheating of localized portions of the vapor, as occurs when the vapors are allowed to pass through a tube of relatively larger diameter without an internal core. In the rows of tubes below the inlet row B, I preferably provide cores possessing catalytic activity and in this respect I may use ferrous oxide provided in molded concrete rods or bars. This concrete bar is supported centrally within said lower rows of tubes and experience has demonstrated that the presence of the lferrous oxide facilitates conversion and produces a larger quantity of the desired fractions than can be obtained when such cores are omitted. In this respect I may also add superheated steam in suitable quantities, for example, one to four percent by weight, to the oil vapors before the latter enter the converter, which steam has been found beneficial in minimizing carbon formation, in reducing the formation of fixed gases during conversion and in aiding in the production of a final product having high anti-knock value as a motor fuel. The catalytic cores, indicated at 13, in the lower passes ofthe converter are supported by means of wire legs 14, so that said cores occupy an axial or central position longitudinally within the converter tubes, causing the heated oil vapors to continue to travel in a thin annular stream through the converter elements. The ends of these elements are united by means of the headers 7 or their equivalents. The entrance protions of the inlet pass of tubes B are provided with carefully formed orifice cores 15 which ,a tube possessing an internal diameter of two and five-eighths inches may possess an internal diameter of two and one-- quarter inches, each of said orifice cores being approximately six inches in length. These cores serve to regulate the effective vapor passage area at the inlet end of each of the tubes in the row B, enabling such area in each tube to, be substantially the same. This provides for uniform distribution of the oil vapors to all the tubes in the upper pass, particularly preventing channeling of such vapors and insuring an even and uniform flow of the oil vapors through all of said tubes.

It has been found that in maintaining the vapors while undergoing conversion at temperatures from 1000 F. up to approximately 1200 F., that the anti-knock value of the product produced is far superior to that obtained when conversion takes place at temperatures below 1000 F. This quality of the product is indicated by a higher specific gravity. The present invention is therefore directed to a process wherein such elevated tem- 'peratures are utilized whereby an improved anti-knock motor fuel, which 1s generally indicated by a higher specific ravity, is obtained. I realize that it has een proposed heretofore to use conversion temperatures of between 600 and 800 F. and am well acquainted with the anti-knock motor fuel product obtained from such prior 1n`rcess but by practice of the present invention it is set forth Y that not only is a better product obtained for use as a motor fuel but far better operating conditions are maintained in the converter unit itself.

In Figure 4 a modified form of the invention has been disclosed wherein the inner tube 9a, instead of receiving its heat from the converter proper, passes completely through the tubes B and is connected with an exterior heater 5a. In this form of the invention the orifice cores of the invention are omitted and the heater 5a may be of any suitable type.

What is claimed is:

1.. The method of producing low boiling point hydrocarbons from hydrocarbons of relatively higher boiling point, which consists in passing a stream of oil va or in the form of a thin annular trave ing body through a multiple pass externally heated conversion coil, and in applying heat to the oil vapor during its passage through the initial pass of said coil from both the exterior and interior of the traveling vapor body so that said oil vapor is rapidly and substantially instantly heated from a temperature at which substantially no cracking occurs to a cracking temperature in excess of 1000 F. during the passage of said vapor through the initial pass of said coil.

2. The process of converting high boiling point hydrocarbons into low boiling (point hydrocarbons, which consists in passing such high boiling point hydrocarbons in a vaporized form through a heated multiple pass cracking zone wherein said vapors while iiowing through the initial pass of said zone assume the form of a relatively thin annular traveling body, and in applying heat to both the interior and exterior of said' traveling body of vapor while the latter is passing through the initial pass of such zone so that said vapor is rapidly and substantially 1nstantaneously heated from a temperature at which substantially no crackin occurs to an elevated cracking temperature uring its passage through the initial pass of said zone, and in continuing to apply heat to said vapors during the passage of the latter through the remaining passes of said zone at such a rate as to maintain said vapors at a cracklng temperature.

In testimony whereof I affix my signature.

CARY fa. WAGNER.

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