US1981150A - Treatment of hydrocarbon oils - Google Patents

Description

Nov. 20, 1934. R p z TREATMENT- OF HYDROCARBON 0111s File d June 12, 1931 1 2 Sheets-Sheet" 1 8w QN a l'll I /e 72 for:

Jfobert IILyZeZ .%7 W

R ll l a: l 3:11p .s PM E k g sq? N g -L- 1 Nov.20, 1934. R, 'PYZEL 1,981,150

TREATMENT OF HYDROCARBON OILS I v L Patented Nov. 20, v1934 1,981,150 Y TREATMENT OF BYDBOCABBON OILS Robert rm], Chicago, Oil Products Comp ration of South Dakota 111., asslznor to Universal Chicago, 111., a corpo-.

Application June 12, 1931, serial No. 543,758 3 Claims. (01. lee-s7) This invention relates *tothe art of treating hydrocarbon oils for the purpose of obtaining low boiling hydrocarbons suitable for motor fuel from higher boiling hydrocarbons by conversion of the latter at relatively high temperatures.

One of the purposes of the present invention is to obtain a motor fuel of high anti-knock properties suitable for operating motors under conditions which ordinarily cause knocking, or for increas- 10 ing the efficiency of motors by operating under ,relatively high compression. It has been found that motor fuels produced by the high temperature conversion of high boiling hydrocarbons into low boiling hydrocarbons contain a relatively high percentage of unsaturated and aromatic hydrocarbons, which have anti-knock properties.

In the process which I am about to describe, the low boiling hydrocarbons formed from the conversion of the higher boiling hydrocarbons are largely made up of unsaturated and aromatic hydrocarbons, hence the motor fuel is more efllcient than that produced by ordinary processes.

I have heretofore disclosed a process wherein hydrocarbon vapors are brought into direct contact with products of combustion preferably using an eflicient mixing device so that the resulting mixture is at a temperature suitable for the conversion of the heavier hydrocarbons into lower boiling hydrocarbons of high anti-knock value.

In the present invention the principal improvement resides in the recirculation of the'gaseous products of the process, combining the same with the products of combustion, which are the primary source of heat, to cool the said products of 36 combustion before mixing the same with the hydrocarbons undergoing treatment and at the same time causing beneficial reactions resulting in a reduction of gas losses; in an increase in the yield of motor fuel presumably by polymerization of 40 the gases so returned; and in an improvement in the motor fuel product with respect to its antiknock properties as well as with respect to its amenability to refining treatments for the production of finished motor fuels.

In one of its specific embodiments, the invention comprises subjecting hydrocarbons to heat treatment to vaporize the same, mixing the vaporized hydrocarbons with products of combustion of a suitable fuel from a suitable source, subjecting the mixture to a prolonged reaction time to obtain the desired degree of conversion, separating the heavy tar-like components of the reaction products from the vapors and gases and subjecting the latter to fractionation and absorption treatment or treatments to separate the dewell as to permit proper sired relatively low boiling products of the process, returning the reflux condensate from the fractionating turning gases ing the combustion zone but preceding the mixing zone to cool the said combustion gases before mixing the same with the hydrocarbons undergoing treatment and to bring about a reconversion of the recycledgases to increase the yield of desirable low boiling products and to improve their anti-knock and other properties.

Another specific step production of combustion gases without a substantial percentage of free oxygen by burning a fuel with approximately the theoretical quantity of air and with the introduction of a small amount of steam toaid combustion. peratures developed herein may be in excess of 3000" F. The temperatures of the gases are reduced to from 1600 F. to 2500 F., preferably by the addition of steam or water, which in the present invention serves the useful purpose of preventing a large portion of the recycledgases from cracking to the ultimate products of hydrogen and carbon or to mixtures of hydrogen, carbon and less bomplex hydrocarbons.

The third step and one which includes the speciflc improvement of the present invention over the process of my prior patent applications is the introduction of gases from the process by recirculation whereby the temperature is brought down to preferably from 1300 Preferably, the recirculated gases are introduced at a point which will permit the proper time element for conversion of the recirculated gases as admixture of the recirculated gases with the combustion gases before in the above processthe I F. to 1800" F.

zone to the heating zone and refrom the process to a zone succeed- The temintroducing the mixture into the hydrocarbon vapors or admixing the same with the hydrocarbon vapors. This may be provided for in a manner which will be hereinafter described.

In heating oil vapors by means of the direct addition of hot gases, the temperature of the gases when added to the vapors and the manner in which the vapors and gases are mixed are of utmost importance. The higher the temperature of the gases when added to the vapors, the smaller the quantity of gases needed to produce the desired temperature for the conversion of the hydrocarbon vapors, hence the greater the capacity of the apparatus. On the other hand, during the mixing of the gases and vapors at diiferent temperatures, some fractions of the hydrocarbon vapors will temporarily attain temperatures higher mixture.

points, to the full flowing stream of vapor. Where gases of combustion are the sole heating medium, ordinarily they must be cooled before mixing withthe hydrocarbon vapors.

From the mixing zone-the mixture of vapors and heating gases pass through a zone which may be referred to as the time zone, which allows the necessary time for the desired conversion. The

temperature in this zone is maintained as near as possible to that established in the mixing zone; but -,normally a drop in temperature will occur. After the desired conversion has been accomplished, the mixture of heating gases and hydrocarbon vapors is preferably subjected to an abrupt cooling immediately upon discharge from the time zone.

Condensation of heavier conversion products which are formed simultaneously with the lighter conversion products as well as of heavier unconverted products may take place in the initial stage ofthe cooling zone, and these products may be reduced to pitchy or coke-like materials if the cooling is not accomplished uniformly and throughout the body of vapors as well as the walls of the cooling zone. To prevent this undesirable conversion to coke is one of the objects of the abrupt and rapid cooling.

In practice in the present invention,'the above cooling is'preferably accomplished byinjecting in the stream of vapors and gasesdischarging from the time zone, a streamof suitable colder fluid in such proportions that the temperature is brought down thereby to below 750 F. for example, some cooling may be accomplished by suitable interchange preferably direct from the incoming charge to the process. Any suitable cooling fluid, including products of the process, may be used. The heavier, unconverted products or the heavier products of conversion may be separated from the incoming charge by means of a' separator.

The efflux discharged from the time zone is at a temperature of approximately 850 F. to 1000 F., more or less, and when subjected to abrupt 600 F., to 750 F., more or less, results in a condensation of fractions boiling above-these temperatures. The heavy residue from the charge and condensed heavy material is removed from the separator through a cooler and carried to storage. The remainingv vapor-gas mixture, including the gas resulting from the cracking reaction, is passed preferably countercurrent and in direct contact with the fresh charge to the system, separator.

A heat exchange occurs here whereby the temperature of the vapor-gas mixture decreases while a large portion or products of conversion, and the total gases enter the fractionating zone. Substantially all of the heavier vapors are knocked back or refluxed in this zone by proper cooling in the upper part of the fractionating column. The condensed material cooling and collecting zones of the process.

preceding specification.

which enters the 7 all of the charge vaporizes. The total vapors, including vaporized charge,

constituting the combined feed passes the heating tubes at about 600 F. more or less, to be vaporized. Where the feed is passed direct to the fractionating tower, the condensate thus formed returns to the heating zones of the process in admixture with the fresh heated charge. The unc'ondensed vapors and gases pass on to the iig igl e final cooling and collecting zones may consist of conventional coolers, separators, absorbers, etc.

Owing to the suspension of fine, unagglom= erated droplets of liquid in the vapor-gas mixture when saidmixture is cooled in the subsequent zones of the process, a fine fog may be formed :which cannot be readily separated from the gases in which it is suspended. To collect these suspended oil droplets, I may make use of special apparati such as electrical precipitators, impact condensers, fog collectors, etc., and I may also make use of a scrubbing system in which the vapor-gas mixture is passed counter-current to a stream of oil through a contact zone, which permits efiicient scrubbing of the vapor-gas mixture; preferably this zone is under pressure, as I have found that pressure facilitates the removal of the fine suspended droplets.

It is believed that the principles underlying the present invention have been clearly stated in the For the purpose of a more complete understanding of the process disclosed, Iwill now describe a diagrammatic clevational view of apparatus, comprising Figs. 1 and 1A, in which the present process may be carried out. i

It is to be noted that the apparatus shown may undergo many structural changes without necessarily losing its capacity of embodying the process disclosed in this specification or permitting it to be operated according to the principles of my invention.

In order to more clearly enunciate the principles upon which the present invention is based reference will be made to the accompanying diagrammatic drawings which illustrate one form of apparatus for carrying out the process of the invention. Fuel is introduced through line 1 and valve 2 and is burned in burner 5. Simultaneously, primary air for combustion may be introduced through line 1' and valve 2. Likewise steam to facilitate combustion may be introduced through line 1" and valve 2". Secondary air for controlled combustion may be introduced through line 3 and valve 4. Combustion occurs in the furnace '1, which may be arbitrarily dividedinto a high temperature zone A and a medium temperature zone B and to'obtain a marked differential in temperature between the two zones steam or water may be introduced into the combustion zone through line 8 and valve 9.

The hot productsof combustion may be passed through conduit 10, into which may be introduced the recycled gases of the process to cool the gases passing through the said conduit to the desired temperature. The gases are introduced at various about the desired time effect in the mixing and reaction of the said gases with the products of combustion.

The oil is heated in the heating tubes 1'1 of tube furnace 18, the oil vapors passing through line 19 controlled by valve 20 into the mixing chamber 7' where the oil vapors and hot gases are thoroughly mixed. Fuel may be supplied to the burner 13 through line 11 controlled by valve 12. Air may be supplied through line 14 controlled by valve 15. A portion of the recirculated gases may be burned in furnace 18, supplying the same through line 16 controlled by valve 17'. The mixture of oil vapors and hot gases are passed into reaction chamber 21, which may consist of a chamber proper and a cylindrical member '22 arranged to cause the gases to pass through the longest path of travel as indicated by the arrows through the annular space and down to the cylindrical member into the outlet line 23, from where the mixture of oil vapors and hot gases enter the residuum separator 24.

Referring now to the charging oil, it may be fed directly to the heating tubes in the tube furnace or may be fed through heat exchanges into the residuum separator where the major portion is flashed, subsequently being fed to the heating tubes in the manner which I will describe. When the raw oil is fed directly to the heating tubes, it may be by-passed after heating in tubes 17, from line 19, through line 25 controlled by valve 26 into separator 27 and the vapors passed through line 28 controlled by valve 29 into line 19 and from there into the mixing chamber. The unvaporized residue in separator 27 passes through line 27, valve 26', cooler 28', line 29" and valve 25' to residuum storage. Where the charging stock is fed directly, it is pumped through pump 30 through line 31 into absorption tower 32 where it meets the uprising gases, removing from them entrained and absorbed gasoline. The raw oil passes out of the absorption tower into the raw oil receiving tank 33 and may pass through line 34' and valve 35' to pump 34 and through line 35 and, all or in part, through valve 36 into the residuum separator 24, or all or in part, from line 35 through line 75 and valve 76 into line 41 and thence to the tubes 17 through pump 42, line 43 and valve 43'.

A portion of the raw oil from tank 33 may be by-passed through line 77 and valve 78 to pump 37 and fed through line 38 into absorption tower 32. The raw oil passing into the residuum separator 24 meets the hot gases and vapors leaving the reaction chamber and a heat exchange is effected whereby a substantial portion of the raw oil is vaporized and passes through line 39 into the fractionating column 40 which preferably takes the form of a bubble tower. Condensation of the heavier portions of the vapors occurs here, which includes substantially all of the raw oil charging stock which is vaporized in the residuum separator as well as the heavier portions of the products of conversion. The condensed oil passes through ine 41 and is picked up by hot oil pump 42 and pumped through line 43 and valve 43' into the heating tubes. The unvaporized residue from the residuum separator passes down through line 44 and is picked up by pump 45 and pumped through the cooler 46 where it may be passed through line 47 either to'the residuum storage tank through line 48', valve 48, line 29' and valve 25', or the residual oil may be recirculated back into the residuum separator through line 50 and valve 49. In the latter case it is passed through line 50 into the residuum separator through one of several levels controlled by valves 51.

The vapors and gases leaving the fractionating tower pass through line 52 into condensing tower 53, where they are passed countercurrent to a cooling fluid and' are condensed. The cooling fluid may comprise and is preferably aproduct of the process. In one method of cooling, the cooling fluid is pumped through line 54 controlled by .valve 55 through a spray device 56. The condensed product passes through line 57 and is picked up by pump 58 and pumped through cooler or heat exchanger 59, being returned in part therefrom through line 60 into the condenser for cooling purposes. The-remainder of the condensate is passed through line 62 to storage and the flow is controlled by valve 63. A portion of the condensate may be pumped through pump 64 into cooler 65 and out into line 66 into the fractionating tower.

The gases leaving condensing tower 53 together with entrained and absorbed vapors pass through line 67 into the blower or compressor 68 where they are forced up through line 69 and through the absorption tower 32. In the absorption tower the gases are scrubbed countercurrently by the raw oil and the major portion of the condensable material is removed from the gases. The scrubbed gases are then passed through line 70 controlled by valve 71, to be used as fuel in the system or for any other desired purposes.

The pressure upon the whole system may be controlled by valve 71. The pressure upon the individual elements, e. g. the heating coil may be likewise controlled by suitable valves and in general, the pressure may be atmospheric, sub atmospheric or super-atmospheric.

The gases passing through line 70 controlled by valve 71 may be picked up by compressor or pump 71' and passed through line 72 through any one of the lines 73 controlled by valves, 74 depending upon the most suitable point of introduction of the recycled gases into the conduit 10.

As a specific example of the present invention and for the purposesof an illustrative run, the following is given: A gas oil of approximately 32 A. P. I. gravity from a Mid-Continent crude oil may be treated by vaporizing the gas oil or the greater portion of it in a heating furnace at an average temperature of about 875 F. The vapors are passed to themixing zone and mixed with the hot gases of combustion to which have been added a sufllcient amount of the recycled gases to reduce the temperature of the combustion gases to approximately 1400" F. Some precooling of the combustion gases is accomplished by the introduction of water or steam directly into the combustion zone. Approximately 75% of distillate is recovered based upon the oil charged making approximately 10% of residue and 15% of gas, including the loss.

The distillate contained approximately 85% of hydrocarbons of motor fuel boiling range; for example distillate boiling between 100 F. and 437 F., making a yield of motor fuel of approximately 65% based on the charging stock. The motor fuel had an anti-knock value equivalent to approximately 60% benzol in admixture with Pennsylvania straight run gasoline or approxi-' mately 76% of iso-octane in admixture with normal heptane. It is to be understood that the illustrative run serves as an example only and that by varying the conditions of treatment the amounts of recycled gas and the charging stock yields of motor fuel with varying antieknock qualities may be obtained. It is also to be understood that the process may be operated with varying types of charging stocks, including naphthas, kerosene distillates, gas oils, topped crudes, fuel oils, and heavy residuals, adapting the process to 45 the type of charging stock as well as to the results desired.

I claim as my invention:

1. In the vapor phase cracking of hydrocarbon oil by direct contact with combustion gases as the 150 iii 4 heating medium, the method which comprises vaporizing the oil thereby forming hydrocarbon vapors, simultaneously generating combustion gases substantially devoid or free oxygen by burning fuel in the presence of a volume oi air containing substantially no more than the requisite amount of oxygen to combine with the fuel whereby the combustion gases are formed at a temperature in excess of 300 0 F., cooling the thus generated combustion gases to a temperature between 1600 F. and 2500" F. by the addition of steam or water thereto, then introducing to the combustion gases :1 sufiicient quantity of relatively cool incondensible hydrocarbon gas to lower the temperature of the combustion gases to' between 1300 F. and 1800 F., then commingling the thus formed gaseous mixture with said hydrocarbon vapors .in sufficient amount to raise the latter to vapor phase cracking temperature, maintaining the admixed vapors and gases at the vapor phase cracking temperature for a time period adequate to convert a substantial portion of the vapors into gasoline-like hydrocarbons, and then separating the condensible vapors from the incondensible gases,

2. The method as defined in claim 1 further characterized in that incondensible gases formed in the process and from which said condensible vapors are separated are utilized as said relatively cool hydrocarbon gas.

3. In the vapor phase cracking of hydrocarbon oil by direct contact with combustion gases as the heating medium, the method which comprises vaporizing the oil thereby forming hydrocarbon vapors, simultaneously generating combustion gases substantially devoid of free oxygen by burning fuel in thepresence of a volume of air con taining substantially no more than the requisite amount of oxygen to combine with the fuel whereby the combustion gases are formed at a'temperature in excess of 3000 F., cooling the thus generated combustion gases to a temperature between 1600 F. and 2500 F., then introducing to the combustion gases a suflicient quantity of relatively cool incondensible hydrocarbon gas to lower the temperature of the combustion gases to between 1300 F. and 1800 F., then commingling the thus formed gaseous mixture with said hydrocarbon vapors in sufllcient amount to raise the latterto vapor phase cracking temperature, there being provided a time period between the introduction of said hydrocarbon gas into the combustion gases and the commingling of the gaseous mixture with the hydrocarbon vapors to permit a preliminary conversion of the hydrocarbon gas, maintaining the admixed vapors and gases at the vapor phase cracking temperature for a time period adequate to convert a substantial portion of the vapors into gasoline-like hydrocarbons, and then separating the condensible 10f vapors from the incondensible gases.

' ROBERT PYZEL.

Images