US1782676A - Method of cracking and processing petroleum hydrocarbons - Google Patents

Description

J. C. BLACK Nov. 25, 1930.

METHOD OF CRACKING AND PROCESSING PETROLEUM HYDROCARBONS Original Filed May 17 2W e.. MLM -N` Patented Nov. 25, 1930 UNITED 'STATES PATENT OFI-icaA JOHN C. BLACK, OF WILMINGTON, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGNMENTS,

T0 GASOLINE PRODUCTS COMPANY, INC., OF WILMINGTON, DELAWARE, A COR- PORATION 0F DELAWARE METHOD 0F CRACKING AND PROCESSING- PETROLEUM HYDROCARBONS Application led May 17, 1924, Serial This invention relates to certain new and useful improvements in petroleum hydrocarbon cracking and more particularly to my petroleum hydrocarbon cracking processes, Patents Nos. 1,426,813 and 1,456,419, also to my application No. 602,439, and this application is a continuation in part of the above patents and application.

In my application No. 602,439 I describe a method of introducing fresh supply oil into the cracking or converging system by having -a separate heater for the preliminary heating of the fresh oil or make-up oil and introducing it into the carbon precipitating chamber or direct into anexpansion drum-from whence it goes into the fractionating tower. By my new method, I do not use a separate heater setting but use a heating -coil which I have denominated an economizer coil and which I set in the terminal combustion space of the main furnace, the coil in that position absorbing` suicient heat to obtain satisfactory results. Furthermore, by my new arrangement of apparatus, I am enabled to nass cycle stock through the economizer coil; this stock is the same as that passing through the main cracking coils and may be drawn from the same source of supply. I am also able to introduce new make-up oil through the economizer coil and discharge it either into the mixing chamber under pressure or into the header connecting with `the fractionating tower, as described in my application No. 602,439.

In the apparatus disclosed in this application the main heating and cracking coils, together with the carbon precipitatlng chamber or digester and the means for operating under pressure are the same as described in my Patents Nos. 1,426,813 and 1,456,419, so that if I am introducing-the economizer oil into the carbon precipitating chamber or digester, as the case may be, it will be under such pressure as to overcome the pressure prevailing in the mixing chamber which is such as to materially prevent vaporization of the cracked oils therein, that is substantially in a liquid phase whereas if I discharge the economizer oil into the header or fractionating tower direct, I will not be compelled to No. 714,070. Renewed April 17, 1930.

carry such a high pressure, for the reason that the temperature of the oil in the economizer coil is lower than that in the main cracking coil, and, therefore, its vapor pressure is less, but I carry sufficient pressure on the economizer coil at all times to prevent material vaporization irrespective of the manner of discharge.

My preferred method of operating is to so regulatel the quantity of oil passing through the economizer coil as to bring its temperature to a' degree of heat approximating its incipient cracking point or preferably to a point below its carbonizing point,

in order to prevent fouling of the tubes of the economizer coil. The desired temperature will usually be between six and seven hundred degrees Fahrenheit for most oil but it can be operated at a higher temperature if desired or even lower one, but I prefer to operate at a temperature of six hundred to seven "hundred degrees Fahrenheit. When this temperature is attained, the oil is injected into the mixing chamber, wlierein it intermingles with the highly heated oil coming from the main heating or cracking coils, whereby its temperature is suddenly increased to an exceedingly active cracking` temperature, the pressure being maintained in the mixing chamber sufficient to prevent material vaporization therein, from whence the mixture of oils passes to the heat exchanger, if one is employed, and then to the presure reducing and discharge valve. The oil pumped through the economizer coil is either fresh make-up oil or cycle stock 0btained from the supply coincidently pumped through the main lheating or cracking coils. This 1s my preferred method of operating rather than to discharge the economizer oil direct to the fractionating tower, although this may be found desirable at times and the apparatus is so constructed as to permit of operating in that manner.

The exceptional results obtained by the introduction of economizer oil into the highly heated cracked oil present in the mixing chamber is due, I believe, to the exceedingly is practically instantaneous in its rapidity,

and is of such degree as to constitute an explosive shock to the molecules of the hydrocarbons, especially in view of the fact that the pressure maintained on the hydrocarbons is suHicient to prevent any material vaporization with its resultant cooling effect, thereby holding the oils in a liquid Contact at the active cracking temperature due to their mixture; as for instance, if the econoniizer oil enters the mixing chamber at 700o Fahrenheit and the ingoing primarily cracked oil is 900o Fahrenheit and the ratio of economizer oil to the primary oil is as one is to two, then the resultant temperature of the mixture is 830O Fahrenheit and the instantaneous rise of temperature of the economizer oil will be 130O Fahrenheit and which it will attain in a fraction of a second, whereas if it was heated in a coil to a corresponding degree, it would require several minutes to attain such increase. In other words, the heating time element is probably two to three hundred times as fast by direct admixture as by extraneous heating and it is this rapid heating of almost explosive violence that produces the breakdown of the molecular structure and causes cracking. I cannot otherwise account for the results obtained by this method as against slower heating, as the yield of gasoline may equal or even exceed the amount obtained in the primary crac-king operation wherein the temperature may be 75 to 100D Fahrenheit higher, the same oil being used in both circuits.

Another object of my invention is the improved operating condition which is brought about by the introduction of the secondary supply of oil into the primary supply. It seems to have a marked influence on the character of the carbon formation by creating a condition whereby the carbon is precipitated in a more finely divided state and which is less coherent and is more easily cleaned out of the chamber, and by this improved condition thus created, I am enabled to operate for a much longer time without shutting down for carbon removal; heretofore, the running time was largely dependent upon the accumulation of carbon at the point of exit from the chamber, this accumulation gradually building up a differential pressure between the inlet and outlet pressures to a point that was impractical to further operate at and cleaning was necessary. By my new arrangement, the practical running time is increased to a very great extent and which I have found to be four to five times as long and in some cases even more. This, however, is largely dependent upon the character of the oil being used in the secondary coil.

The setting of the main furnace may be such that an auxiliary fire may be used to give additional heat to the economizer coil and, under some circumstances, this may be desirable. In my drawing of the apparatus, I show the auxiliary firing or combustion chamber but it is to be understood that this may be dispensed with and good results obtained thereby. I also show in the drawing a heat exchanger apparatus designed to extract heat from the outgoing cracked or converted oil and exchange it to the ingoing oil to be cracked. This may be dispensed with but it is a heat economizer and I show it as a part of the apparatus but it is not an essential part thereof.

I also show a preheater coil situated in the hottest portion of the furnace to act as a protector and absorber of radiant heat and excessive heat that would otherwise impinge upon the final or terminal heating coils. This coil and its function s described in my copending application No. 712,156 filed May 9, 1924.

I am also showing fractionating towers wherein the vapors are fractionated and separated into their various products.

I am showing all this apparatus so that anyone familiar with the art to which this invention relates may be enabled to construct and operate the complete plant.

As before mentioned, I may use an auxiliary fire or supply of heat to obtain closer regulation of the heating in the economizer coil and also to increase the quantity that may be heated; this also enables me to secure a somewhat higher heat in the oil or hydrocarbons passing through the economizer coil and thereby increase the final cracking effeet.

A heat interchanger may also be employed to preheat the ingoing oil to the economizer coil and extract heat from the outgoing oil, thereby increasing the heating effect in the economizer coil.

The carbon precipitating or mixing chamber will act to catch any free carbon which can be periodically removed by blowing down as described in my Patent No. 1,456,419, or it may be removed by disengaging the end clean-out closures and removing the carbon or carbonaceous material by hand or otherwise.

By the above described method of operation, the mixing chamber becomes a heating element by the fact that the ingoing oil is of higher temperature from the main cracking coil than that entering from the economizer coil and heat is imparted to the latter.

In my Patent No. 1,426,813, I describe a reaction chamber or digester wherein the cracking reaction is continued outside of the heating coils and it is to be understood that the application of the economizer coil to that type of apparatus is feasible and practical and by the introduction of oil from the economizer coil into' the reaction chamber or digester will bring about an increased yield with to any appreciable extent.

The mixing chamber and its connections p may be so arranged as to create a gas space in the upper portion of the chamber, where gases and possibly some vapors that are generated by the process may accumulate. These gases or vapors will, of course, be under the pressure maintained in that portion of the apparatus and will-actas a cushion or shock absorber on the pumping system and will have a tendency to smooth the action of the pump and relieve any undue hydrostatic pressure on the tubes, gauges, valves, and other parts of the apparatus.

In the yheating and cracking furnace, as depicted in the accompanying drawing, the primary cracking operation is accomplished in the coils substantiall as described in my Patent No. 1,456,419. n this case, the injection oil from the economizer coil is introduced into the mixing chamber at a coincident point with the main portion of cracked oil entering from the primary cracking coils.

The apparatus is so arranged in regard to tanks, pumps, lines, coolers, condensers, etc., that the oil or hydrocarbons circulated through the economizer coil can be either a virgin make-up oil or it may be derived from the heav or high-boiling point fractions separatedl in the fractionating apparatus. There is also arrangement made for bypassing the economizer oil from entering the carbon precipitating or mixing chamber and passing it directly to the vaporizin and fractionating tower. This may be deslrable at times either for control or for introducing stocks into the cracking system. I have fou'nd that when a heavy fuel oil or crude oil or in fact any oil which on normal distillationl (that is not destructive distillation) will produce viscous residues or fractions, if introduced into the cracking system through the economizer coil and heated to a degree approximating its cracking point, then discharging it into the carbon precipitating or mixing chamber or into a digester Lor reaction chamber, that the heavy viscous fractions contained therein are cracked and rendered comparatively non-viscous so that the residues or heavy fractions obtained by this method of operating are easily pumped or otherwise -disposed of.

In this system I prefer to use a separate pump for each oil circuit-one for the economizer circuit and one for the main cracking circuit, for several reasons: First, different stocks may be used in the two circuits and, second, better control may be obtained. It is quite practical, however, to use one large pump to feed all the economizer coils and have separate pumps for each main cracking unit where several such units are in a battery; likewise, a large pump may be employed to feed all the maincracking coils but I prefer separate pumps on each cracking unit. This, however, is immaterial to the process but is here-mentioned to guide anyone who may wish to construct an apparatus embodying this invention.

Referring to the drawing: Figure 1 represents the complete apparatus in part section and part elevation, and Figure y2 represents the cracking furnace in section at right angles to that shown in Figure 1. Figure 2 shows the mixin chamber in its correct p0- sition, whereas in igure 1, it is shown below the furnace and is so depicted for clearness and simplicity; the balance of the apparatus is so disposed in the drawing as to show the relation of one part to another and is not meant to show the actual position of the various parts. Similar numbers in Figure 1 and Figure 2 represent like parts.

In the drawing l represents the furnace; 2 the preheater coil; 3 the pipe connection from the preheater coil to the intermediate coil 4, and 5 the connection from the intermediate coil 4 to the final or cracking coils 6; 7 is a pipe connection from the final coils to the carbon precipitating or mixing chamber 8; 9 is a blow down connection; 10 is a discharge connection from the carbon precipitating or mixing chamber to the heat exchanger 11; '12 is a connection from the heater exchanger to a bypass trap 13; 14 is a connection and 14 is a pressure reducing valve therein connecting the bypass trap 13 with the discharge header 15, which in turn is connected into the fractionating tower 16, which is divided in various sections 17, 18 and 19; 20 is a vapor pipe connecting the tower 16 into the fractionating tower 21; 22 and 23 are boiling decks for fractionating the vapors and condensates; 24 is an analyzer or refluxing condenser; 25 is a vapor line connecting the tower 21 with the condenser; 25 is a valve in the vapor line 25; the condenser connectsv with the look box 26 and through pipe 27 to the light naphtha tank; from the outlet end of the condenser there is also a connection 28 which acts as a gas vent connected to a gas header not numbered. Tower 21 is fitted with a draw-off arrangement 29 connecting with a cooler which in turn connects to the supply tank and heavy naphtha tank through look box 30 and lines 31 and 32. Compartment 17 is connected by pipe 33 and valve 33 to the residue tank; compartments 18 and 19 are fitted with draw-off pipes 34 and 35 respectively and are fitted with valves 34 and 35 and a crossover connection and valve 36 between the lines 34 and 35; lines 34 and 35 are connected to the cooler; from the cooler are look boxes and connections 37 and 38 connecting to the supply tank and the intermediate naphtha tank respectively. The tower compartments are fitted with spray devices 39 and 40, connected by pipe connections 41 and 42, controlled respectively by valves 41 and 42, and thence by` pipe 43 to the pump 44. There is a connection 45 and valve 45 leading from pipe 43 and connecting with the analyzer 24. There is also a connection 46 from the analyzer controlled by valve 46 and connecting with the pipe 35 leading to the cooler. There are connections 47 and 48 connecting with pipes 35 and 46, respectively, which connect with the fractionating tower 21. The bypass trap 13 is inserted in water or water jacket 49 and is fitted with a blow-off connection 50; from a point above the bottom a connection 51 is made to the cooler 52 and through line 53 it connects to the control board 54 on which are mounted the control valves and pressure gauges. On the control board the line 53 is fitted with a terminal pressure gauge 55 and a pressure reducing valve 55', from whence it connects to two tanks, one for slop oil and one for cracked oil, through the line 56 which is fitted with branch lines and valves connecting with each tank. The pump 44 takes suction through line 57 to the intermediate naphtha tank and also the heavy Ynaphtha tank through branch connections and valves to each tank.

Pump 58v takes suction through line 59 with the water tank, the slop tank and the supply tank through branch pipes and valves to each tank; pump 58 discharges through line 60 to the control board 54 whereon are mounted a pressure control valve 61 and a pressure gauge 62 in line 60 which extends to and is connected into the preheater coil 2; between lines 56 and 60 is a bypass valve and connection 63. The pump 64 has a suction connection through line 65 and valve 65 to the fresh oil supply tank 84; it also has a branch suction line 66 and valve 66 connecting to the supply tank 83; pump 64 has a discharge pipe 67 connecting with the control board`54 whereon are mounted a pressure control valve 68 and a pressure gauge 69; between, lines 67 and 60 onvthe control board is a bypass valve and connection 7 0; from the control board the line 67'extends to the branch connection 71; from the latter extends a line 72 and valve 72 connecting to the heat exchanger 11; the heat exchanger has a corresponding outlet pipe 73 connecting to the pipe 74; from the branch connection 71 extends a line 74 and valve 74 to the inlet side of the economizer coil 75 in furnace 1; the outlet side of coil 75 connects with the pyrometer fitting 76 which acts as a branch fitting; one branch 77 and valve 77 connects with the mixing chamber 8 and the other branch 78 with its valve 78 connects to the header 15. The furnace 1 is litted with a burner 79 and also an auxiliary burner 80, also a smoke stack 81; the coils 6 are fitted with pyrometer fittings 82 and 82'; 83 is the oil supply tank and 84 is the make-up oil or fresh supply tank.

There are a number of instances where I show on the drawing fittings, valves, etc., which I have not numbered, as they are selfevident in character and anyone familiar with the art to which this invention relates will readily understand their significance and function.

Having now described my apparatus, I will describe its operation:

The pump 58 is started and takes suction on the supply tank 83, through line 59 and discharges the oil through line 60 to the control board 54 and through the pressure regulating valve 61 in line 60, from whence the oil passes to the preheating coil 2, then to the coil 4 by way of pipe 3, then into the final heating and cracking coil 6 by way of pipe 5; from the cracking coils 6 the oil passes to the carbon precipitating and mixing Chambcr 8 by way of pipe 7. At a point in the mixing chamber near the pipe 7 is an entering pipe 77 connected to the economizer coil 75 which is located in the terminal passes of the furnace 1; this coil may have a supply of additional heat furnished by the burner 80, if so desired, in order to increase its capaclty and cracking effect. The coil 75 may be supplied with o1l through the pipe 74 which connects with the valve 68 on the control board 54; in the line 74 is a bypass 72 connecting with the heat exchanger 11 designed to supply heat to the oil going to the economizer coil and extracting heat from the outgoing oil from the carbon precipitating and mixing chamber 8; from the valve 68 on the control board extends a pipe 67 connected to the pump 64 which is taking suction on the supply tank and will be pumping for the time being the same oil as is being pumped by the. The oil in the two distinct c1rpump 58. cuits is heated by the heat supplied by the burner 7 9 and, if desired, the burner 80 may also supply additional heat. The oil in the primary cracking coils 2, also coils 4 and 46, will be heated to an active cracking tempefiature, the quantity of oil pumped and the supply of heat being so regulated as to bring about this result. Now the oil passing through the secondary or economizercoil is so regulated, as to quantity, as to bring its temperature to a point approximating its cracking point more or less- (as previously stated, the quantity pumped may be increased by employing additional heat from the burner 80, care being taken to so regulate the heat as to maintain a substantial heat differential between the two oils as they leave the heating coils) the two streams of oil are now introduced into the mixing chamber 8 where the oil of lower temperature is instantaneously increased in temperature from an incipient cracking temperature to one of active cracking, the cracking action being highly accelerated by the rapidit of the increase of heat. This reaction an the two heating steps are carried on under a high pressure sulicient to prevent material vaporization, the admixture of the two being in a liquid condition. The mixture of oils then passes through the carbon precipitating chamber or mixingI chamber (where any free carbon is precipitated) into the heat exchanger/11, thence to the bypass tra 13 which is in open communication throug the line 51, cooler 52 and line 53 to the terminal pressure reducing valve 55'; the pressure being observed by the gauge 55; from the valve e 55' extends a line 56 to the slop tank or the cracked oil tank. From the bypass trap 13 there is connected an outlet pipe 14 and pressure reducing valve 14' located therein and which connects into the header 15, which in turn connects into the fractionatin tower 16. The header 15 is simply a manifold to receive similar connections to 14 from other units in a battery of cracking units and where one tower will take care of the vapors of a battery of units.

In operating in this manner, I prefer to use a terminal pressure of one thousand pounds, more or less, with an inlet pressure suliiciently higher to overcome the friction of the pipe, bends, etc., and which may be as high as one thousand five hundred pounds, or

more. V

The pump 64 may take suction on the fresh supply tank 84, through pipe and valve 65', if it is desired to replenish the system with fresh oil, or the fresh oil may be introduced into the system by putting it into tank 83 and which may be done if the makeup oil is a distillate or is a clean oil that would not cause fouling of the primary coils; whereas, if the make-up oil is a heavy grade, such as fuel or crude oil which might cause fouling of the tubes of the primary coils, then the make-up oil should be stored in tank 84, so that pump 64 may introduce it into the system through the economizer coil where danger of carbonizing or fouling is a minimum. If, for instance, fuel or crude oil were introduced into the system by putting it into the supply tank 83, then the pump 58 would discharge the heavy oil through the primary cracking coils which would rapidly foul and cause more or less trouble, whereas if the pump 64 handles the make-up or fresh supply oil it can be so regulated that the heating effect in the economizer coil will be such that nothing more than incipient cracking will take place therein, the active cracking taking place in the mixing chamber or carbon precipitating chamber, where carbon can be readily cleaned out or purged. By this arrangement, the coils will remain clean and practically free of carbon.

The economizer coil also has a bypass connection 78 in which is a pressure reducing valve 78'; this line is connected to the header 15 and is used as a bypass in case of trouble to line 77 or if it is desired to vaporize a stock in the fractionating towers without cracking it in the mixing chamber.

The pump 58 may be operated to furnish the ordinary or economizer coil with its supply of oil and at the same time furnish the primary coils with their supply of oil-(by operating in this way both coils will be supplied with the same grade of oil). The two coils will function in an identical manner as if each had an individual pump, the regulation of the supply to each coil being controlled by suitably situated valves. For instance, pump 58 can take suction on the supply tank 83 and discharge through line 60 to the control board 54 and by having Valve 61 open, the primary coils 2, 4 and 6 may be supplied and also valve may be open through which the secondary or economizer coils may be supplied with oil.

The same arrangement also applies to pump 64 which may take suction on the supply tank 83 and also on the fresh supply tank 84 and discharge through line 67 to the control board 54 and with valve 68 open, together with valve 7 2' or 74', the secondary or economizer coils will be supplied with oil, and, if valve 70 is simultaneously opened, the primary coils will be supplied with oilthe quantities to each coil being controlled by valve 70 for the primary coils and valve 72' or 74 for the secondary coils.

When I wish to blow down the system, I shut o the supply of oil to pump 58 and open the suction lnto the water tank, the pumpthen discharging water to the coils and driving the oil ahead of it; the valve 14' being closed, the oil and water discharges through the bypass trap 13, through pipe 51, cooler 52, pipe 53, pressure reducing valve 55' and line 56 to the slop tank, or if the oil is coming clean it is run into the cracked oil tank. When the oil is displacedin the tubes, then the blow-oil' connection 9 on the chamber.8 is opened and the carbon or carbonaceous material is blown out of the tubes and carbon precipitating chamber.

To simultaneously blow down the economizer coil with the primary coils, I close valve 68 on the control board and open valve 70, thereby admitting water from the pipe 60 and pump 58 into the pipe 67 and through the valves 72' and 74' to the economizer coil which will discharge into the carbon precipitating chamber through pipe 77 and be discharged through the blow-olf 9.

It is essential when discharging pump 64 pressure will be a thousand pounds, more or less. When operating to discharge into the header 15, comparatively low pressure can be employed. When the oil and vapor discharge from the header 15, they enter the tower 16, wherein they are fractionated; from tower 16 the vapors pass to tower 21 where they are further fractionated. Tower 16 will separate in compartment 17 a heavy residue which is cooled and run to the residue tank. Tower 16 will also separate in compartment 18 a cycling stock which may be withdrawn through pipe 34 and valve 34 to the cooler and pipe 37 to the supply tank 83 to be rerun. Tower 16 will also separate in compartment 19 an intermediate naphtha stock which may be withdrawn through pipe 35, valve 35', through the cooler and pipe 38, to the intermediate naphtha tank. The intermediate naphtha may be sprayed into the compartment 18 through spray pipe 39 by opening valve 36 and closing valves 35 and 47, or it may be run to the lower part of the tower 21 through valve 47, having valves 35 and 36 closed.

The residue from tower 21 is a. heavy naphtha and may be drawn off through connection 29, thence to the cooler, look box 30, pipe 32, to the heavy naphtha tank, or it may be run to the supply tank 83 througlrline 31.

The pump 44 is arranged to take suction on the intermediate naphtha and also on the heavy naphtha tanks, so that these stocks may be sprayed into the various tower compartments as a scrubbingr and condensing meium and to be revaporized and again fractionated, or they may be used as a condensing medium in the analyzer 24, the oil entering through pipe 45 and valve 45 and discharging through pipe 46 and valve 46 through the cooler, then back to the original tank from which it came; or by closing valve 46 and opening 48 the oil may be discharged into the lower portion of tower 21 to be refractionated.

The final vapors leaving tower 21, through the analyzer 24, can be made a light naphtha containing a large percentage of gasoline, or it can be made a crude test gasoline not requiring further distillation to refine it.

What I claim as new and desire to obtain by Letters Patent is:

1. The process of cracking hydrocarbons in substantially the liquid phase comprising heating a primary supply of hydrocarbons in a heating furnace to a degree sufficient to crack them, then discharging them into a carbon precipitating and reaction chamber and maintaining throughout the cracking system a pressure sufficient to prevent material vaporization of the hydrocarbons, and simultaneously heating in a tubular heating element a secondary supply of hydrocarbons in the terminal combustion spaces of the primary heating furnace and maintaining thereon, to the point of pressure release and discharge, sufficient pressure to prevent material vaporization thereof.

2. The process of cracking hydrocarbons in substantially the liquid phase comprising heating a primary supply of hydrocarbons in a heating furnace to a degree sufficient to crack them, then discharging them into a carbon precipitating and reaction chamber and maintaining throughout the cracking system a pressure sufficient to prevent material vaporization of the hydrocarbons, and simultaneously heating in a tubular heating element a secondary supply of hydrocarbons in the terminal combustion spaces of the primary heating furnace and maintaining thereon sufficient pressure to prevent matel rial vaporization thereof, then discharging the heated hydrocarbons of the primary and secondary supplies into a fractionating apparatus, then condensing and separating the various fractions, and returning to the cracking system those fractions suitable for recracking.

3. The pro-cess of cracking hydrocarbons in substantially the liquid phase comprising separately heating in a single furnace two supplies of hydrocarbons-first heating a primary regulated supply in a continuous heating element in a single pass through the furnace to a temperature sufficient to actively crack them and, secondly, hea-ting a secondary regulated supply in a single pass through a continuous heating element, so disposed in said furnace whereby its heating effect is obtained from waste gases of the primary heat ing effect, and so regulating the secondary supply that the degree of heating obtained thereby approximates its incipient cracking point, then discharging the primary and secondary supplies into a mixing chamber whereby the temperature of the secondary supply is suddenly increased to an active cracking degree and maintaining on the primary and secondary heating elements and mixing chamber a pressure sufficient to prevent material vaporization thereof and maintaining said pressure to the point of pressure release and discharge.

4. The process of cracking hydrocarbons in substantially the liquid phase comprising separately heating in a single furnace two supplies of hydrocarbons-rst heating a primary regulated supply in a continuous heating element in a single pass through the furnace to a temperature sufficient to actively crack them, and, secondly, heating a secondary regulated supply in a. single pass through a continuous heating element, so disposed in said furnace whereby its heating effect is obtained from waste gases of the primary heating effect, and so regulating the secondary supply that the degree of heating obtained thereby approximates its incipient cracking point, then discharging the primary and secondary supplies into a mixing chamber whereby the temperature of the secondary supply is suddenly increased to an active cracking degree and maintaining on the primary and secondary heating elements and mixing clianiber a pressure sufficient to prevent material vaporization thereof and maintaining said pressure to the point of pressure release and discharge then discharging the h ot mixture of hydrocarbons into a fractionating apparatus wherein the various fractions are separated and the hydrocarbons suitable for recracking are returned to the cracking system for further cracking.

5. The process of cracking hydrocarbons in substantially the liquid phase comprising heating a primary supply of hydrocarbons in a heating furnace to a degree sufficient to crack them, then discharging them into a carbon precipitating and reaction chamber and maintaining throughout the cracking system a pressure sufficient to prevent material vaporization of the hydrocarbons, and simultaneous'j.; heating a secondar)v supplyof hydrocarbons in the terminal combustion spaces of the primary heating furnace to a temperature suiiicient to reduce the viscosity of the residues resulting from the vaporization and fractionation of the said secondary supply of hydrocarbons and maintaining thereon a pressure suiiicient to prevent material vaporization thereof and maintaining said pressure to the point of pressure release and discharge.

6. The process of cracking hydrocarbons in substantially the liquid phase comprising heating a primary supply of hydrocarbons in a heating furnace to a degree suicient to crack them` then discharging them into a carbon precipitating and reaction chamber and maintaining throughout the cracking system a. pressure sufficient to prevent material vaporization of the hydrocarbons, and simultaneously heating a secondary supply of hydrocarbons in the terminal combustion spaces of the primary heating furnace to a temperature suflicient to reduce the viscosity vof the residues resulting from the vaporization and fractionation of the said secondary supply of hydrocarbons and maintaining thereon a pressure suiiicient to prevent material vaporization thereof to the point of pressure release and discharge, then discharging the primary and secondary supplies of .hydrocarbons into a fractionating apparatus, and returning to the cracking system those fractions suitable for recracking.

7. The process of cracking hydrocarbons in the liquid phase comprising heating a primary supply of hydrocarbons to a temperature sufficient to crack them, then discharging them into a mixing chamber wherein is introduced a secondary supply ofhydrocarbons heated in the same furnace to a degree approximating its incipient cracking point, the mixture of hydrocarbons supplying sufficient signature.

JOHN C. BLACK.

Images