US3111395A

US3111395A - Apparatus for the pyrolysis of hydrocarbonaceous materials

Info

Publication number: US3111395A
Application number: US32310A
Authority: US
Inventors: Sweeney Maxwell Patrick
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-05-27
Filing date: 1960-05-27
Publication date: 1963-11-19
Anticipated expiration: 1980-11-19

Description

Nov. 19, 1963 M, P. SWEENEY 3,111,395

APPARATUS FOR THE PYROLYSIS OF HYDROCARBONACEOUS MATERIALS Original Filed March 18, 1958 2 Sheets -Sheet l 79 F/ G. 7 4m 75 5/ l A? and STEAM 2e INVENTOR. /2 Maxwefl PU/f/C/f Sweeney F/G BY his af/omeys United States Patent 3,111,395 APEARATUS FOR TIE PYROLYSIS 0F HYDRO- CARBONACEOUS MATEREALS Maxwell Patrick Sweeney, Philadelphia, Pa. (234 /2 5. Bonnie Brae St, Los Angeles 57, Calif.) Continuation of application Ser. No. 722,195, Mar. 18, 1958. This application May 27, 196i), Ser. No. 32,310 2 Claims. (Cl. 23284) This invention relates to a process and apparatus for the pyrolysis of hydrocarbonaceous materials and particularly to a process of this general class which is especially adapted to the production of valuable gaseous, liquid, and solid products.

The invention has many different applications, for example, in the production of valuable gaseous and liquid products and coke from petroleum residues and low value gaseous hydrocarbons; in the gasification and carbonization of coal, lignite and peat; and in petroleum refining.

Prior to the present invention, a number of processes have been suggested for converting lower value hydrocarbonaceous materials, such as lower paraflins, residual fuel oils and coal to more valuable gaseous and liquid products and coke in which the heat necessary for the conversion is introduced by means of hot, finely divided solids. In some cases these solids are used in the form of a fluidized bed.

The difliculty with the fluidized bed technique is that it is inherently inflexible. Required reaction time, temperature, and other conditions vary with different feed materials and products, and it is desirable to have an apparatus capable of handling a variety of different feeds to make a variety of different products. Vessels suitable for holding a fluidized bed must, however, be designed for a limited range of operating conditions, and are not easily altered to different conditions. Moreover, processes requiring short contact times, i.e. below about 0.5 second, cannot be carried out in fluidized beds because such beds have a built in minimum contact time of at least 0.5 second. Furthermore, contact between gas and solids in a commercial size fluidized bed is ineflicient and nonuniform.

To overcome the inherent inflexibility of the fluidized bed the elongated tube technique is sometimes resorted to. This involves injecting the hydrocarbonaceous feed into a hot moving stream of gases and dispersed solids. After a sufficient time the stream of solids and reaction products is sent to a suitable separation device, such as a cyclone separator and from which the gasiform products are recovered.

While the elongated tube technique is more flexible than the fluidized bed, it too has drawbacks. For example, in pyrolysis processes when the reaction stream is introduced into the separation device high molecular weight molecules, e.g. pitch molecules, are often still being produced. Once the solids have been separated there is no longer any place for these molecules to deposit except on the walls of the separator and the offtake pipe. Pitch and the like does deposit there and is very diflicult to remove.

If it is attempted to avoid this drawback by quenching the reaction stream before delivering it to a separation device, the solids are unnecessarily cooled, and hence valuable heat is lost.

In addition to the problem of separating solids from the gasiform product, considerable difliculty is often encountered, in elongated tube processes, in entraining solids into a moving stream of gas, particularly when the direction of flow is substantially horizontal. Also, when the gas-entrained solids stream changes in direction, as in an elbow, de-entrainment and irregular re-entrainment tend to take place. Thus, the ratio of solids to gas tends to vary. This causes thermal instability since minor variations in the instantaneous flow ratio between the heat carrying solids and the reactant stream produce important diiference in reaction temperature.

'It is an object of the present invention to provide a pyrolytic conversion process by means of which hydrocarbonaceous material of low value can efficiently be converted to materials of higher value.

It is another object of the invention to provide a pyrolytic conversion process which is inherently flexible and adaptable to a variety of different feedstocks.

It is another object of the invention to provide a pyrolysis process and apparatus which will substantially reduce deposition of pitch on equipment surfaces.

It is a further object of the invention to provide a method and apparatus for the conversion of hydrocarbonaceous materials which is particularly adapted to processes having short reaction times.

It is a further and separate object of the invention to provide a process and apparatus by means of which the difliculties of uneven entrainment of solids into a moving stream of gases is overcome or avoided.

It is a further object of the invention to provide a method 01": pyrolysis which is adaptable to a variety of operating conditions.

According to a principal aspect of the invention these and other objects are achieved by means of a conversion process which comprises introducing hydrocarbonaceous material into a vortically moving mass of gases and solids and introducing a gasiform stream containing entrained hot solids semi-tangentially into said vertically moving mass to provide the heat necessary for the conversion of said materials and to maintain the vortically moving mass.

By semi-tangentially it is meant that a substantial amount of the solids is introduced toward the center of the vortex, rather than along its outer edge. Defined more rigorously it may be said that when solids are in troduced semi-tangentially through an inlet duct into a reactor having a substantially circular cross-section, the axis of the inlet duct lies in a plane tangent to a cylinder concentric with the axis of the reactor and having a radius not greater than the radius of the reactor. Preferably, the radius of the said cylinder is not less than /2 the width of the duct.

By introducing the solids semi-tangentially, it is possible to achieve a more even distribution of solids across the cross-section of the reactor than would be the case were the solids introduced absolutely tangentially, as in a conventional cyclone separator.

The velocity of the stream of solids entering the vortically moving mass will depend on the size and shape of the reactor, the size of the solid particles and the contact time desired in the mass, among other factors. It may range from say 10 ft./sec. to 150 ft./sec., normally between about 40 ft./sec. and about 100.'ft./SC.

The peripheral velocity of the vertically moving mass i self will, of course, also vary with the factors just discussed. A variation in velocity will mso occur along the radius of the mass. Generally the peripheral velocity will be between about 5 and about ft./ sec.

In the vortically moving mass, and in the stream which is introduced thereto, the solids are present in a disperse phase. By this it is meant that the solids concentration not more than about 10% of the loose packed bulk density of the solids. Usually it is between about 0.1% and about 5% of the bulk density, being usually nearer the higher value at the entering stream and near the lower value within the vortical mass.

The hydrocarbonaceous feed may be introduced along with the solids, provided it is added to the solids stream immediately before introduction into the vertical bed, so that no substantial reaction takes place outside the bed. Alternatively it may e introduced separately as a tangential or semi-tangential stream. In many instances, however, it will be preferred to introduce the feed axially into the vortex.

When introduced tangentially or semi-tangentially the feed will normally have a velocity at least equal to the velocity of the mass. When introduced axially it will normally have a velocity of say ll50 ft./sec., usually 30-75 ft./sec.

By carrying out hydrocarbon conversion reactions in a vortically moving mass, in accordance with the invention, it is possible to achieve a relatively short reaction time without the disadvantages of the elongated tube technique. Because of the vortical motion of the mass, solids are thrown outwardly to the walls of the reactor and slide downwardly along these walls. In so doing they screen the walls and tend to prevent pitch deposition thereon. The gaseous conversion products pass out of the vortically moving mass in an upward direction and may be immediately quenched to prevent further reaction.

In accordance with a subsidiary feature of the invention (which has, however, general applicability to divers systems) deposition of pitch and similar materials on passages leading from the conversion zone is prevented by forming the walls of such passages out of a porous material and bringing an innocuous gas under a relatively higher pressure into contact with these walls on the side opposite that to be contacted with the products of conversion. The gas moves through the walls and prevents build up of pitch and like products thereon, either by forming a film on the surface next to the product stream, or when the gas flow is intermittent, by knocking oft small amounts of pitch which may have been deposited.

The process of the invention is applicable to many types of conversion processes including simple pyrolytic conversions of low value hydrocarbons, catalytic conversions, including reforming processes and .gasification and car- 'bonizati'on of coal and other solid fuels.

Because of its great flexibility, the novel process may be used to treat many different kinds of hydrocarbonaceous materials, including solids, such as coal, oil shale, lignite, or peat, liquids such as Bunker C fuel oil, coke oven tar, low temperature coal carbonization tar, crude oil, reduced crude oil, virgin distillate igas oils, catalytic recycle oils, kerosenes, and naphthenes, or gases such as butanes, propane, ethane and methane. It may also be used advantageously for the high pressure hydrogenolysis of oils, for the depolymerization of resins, and for the production of styrene from ethylbenzene, vinyl chloride from ethylene dichloride and ketene from acetone.

The solid material used in the process according to the invention will depend on the process being conducted. If catalytic conversion is being carried out the heat carrying solid will normally be the catalyst itself. In noncatalytic processes it may be coke or char produced during the reactions, sand, alumina or other catalytically inert, refractory material.

The particle size of the solids is not critical but they will in general be between about 0.0008 and 0.04 inch in 1rl'liameter, preferably between about 0.002 and 0.02 1nc Because the invention may be applied to such a wide variety of materials and processes only the most general statement of reaction conditions can be given. The temperature of the vortically moving rnass will in general range from say 950 F. for the catalytic cracking of petro leum to make gasoline to say 2700 F. for the manu facture of acetylene. Pressure may also vary between wide limits, from say 2 p.s.i.a. to 5000 p.s.i.a., depending on the particular process being carried out.

Reaction time, like temperature and pressure, will depend essentially on the particular process being used. For a fluid reactant it may range from say 0.01 second to 2.0 seconds. For a solid reactant the contact time is not significant since the reactant solid and the heat-carryd. ing solid are kept together after separation from the vortically moving mass. The gaseous products of the reaction will be separated from the reaction mass within about 2.0 seconds, however. The invention particularly advantageous in processes requiring reaction times below about 0.5 second.

The process according to the invention may be combined with other conversion techniques, including fluidized bed and elongated tube techniques to form an overall process having improved characteristics. It has been suggested (see Parker application Ser. No. 699,180) that hydrocarbonaceous material be reacted in a preliminary stage in an elongated tube under disperse phase conditions, i.e. such that the density of the stream is not more than say 10% of the bulk density, and then further cracked with a high temperature gas. It has also been suggested to use high temperature solids to furnish the heat in the terminal stage. In these prior processes the products of high temperature cracking are immediately quenched to prevent decomposition of wanted products such as acetylene, or butadiene.

The present technique is particularly well adapted for the final cracking stage in such processes. The present technique has the advantage of employing solids with their higher volumetric heat capacity as the heat carrying medium. At the same time the diflioulties attendant on separation of solids from reactant products in more conventional processes are avoided. In a particularly attractive embodiment of the invention a liquid hydrocarbon first cracked in a moving stream of disperse phase hot solids flowing through an elongated tube, is then put into a fluidized bed to complete the formation of initial products and is finally converted to highly unsaturated materials by introduction into a vortically moving mass of solids.

A subsidiary feature of the invention, used in the embodiment just referred to (though again of wide application) comprises a novel way of forming a disperse phase moving stream of gases and entrained solids. According to this feature of the invention, a shallow bed of hot, aerated solids is formed, and liquid feed is injected into this bed where it is volatilized by the heat of the solids. The resulting vapor passes out of the bed carrying entrained solids with it and additional hot solids are put into the bed to replace those entrained with the gas.

It has been pointed out that the invention is ap plicable to processes for the carbonization of coal and other solid hydrocarbonaceous materials. In one specific embodiment, coal or like material is preoxidized with air or other oxygen containing gas in a first vortically moving mass, to suppress its agglomerating tendencies. The preoxidized material is then introduced in a second vortically moving mass to carbonize it. The solid char or carbonization residue from the second mass is then partially burned in a third vortically moving mass to heat up the remainder and this remainder is used as the source of heat in the carbonization step. Preferably gaseous products of preoxidation are introduced into the third mass where any fuel values they may contain are burned and used to heat the char. If desired, gaseous products of carbonization removed from the second mass may be cracked in a further vortically moving mass to enhance their value. In each of the vortically moving masses referred to the solids which :make up the mass are preferably introduced semi-tangentially into the mass. The temperatures and pressures are those conventionally used in low temperature carbonization processes.

The invention will be further described with reference to the accompanying drawing in which FIG. 1 is a schematic flow diagram illustrating the invention in its simplest form.

FIG. 2 is a fragmentary view showing in more detail a preferred construction for the top of a pyrolysis column which is designed to avoid deposition of tar and similar materials on the apparatus.

FIG. 3 is a view in horizontal section along the line 33 of FIG. 1, showing the position of a send-tangential inlet.

FIG. 4 is a fragmentary view in side elevation again showing the position of a semi-tangential inlet in the system of FIG. 1.

FIG. 5 is a schematic flow diagram illustrating a threestage pyrolysis system embodying the invention.

FIG. 6 is a fragmentary view of the bottom of the apparatus of FIG. 5 showing details of an improved way in which liquid hydrocarbonacecus material may be introduced into a moving stream of dispersed solids.

FIG. 7 is a schematic flow diagram illustrating a system for the low temperature carbonization of coal employing the invention.

Referring first to FIGS. 1 to 4, a system constructed in accordance with the invention comprises a hollow cylindrical column 10 having an inlet 11. As shown in FIGS. 3 and 4, the inlet 11 joins the shell 1d semitangentially. The axis aa of the inlet 11 is tangent to an imaginary cylinder 5 whose radius r is less than /a the radius R of column 10.

Although the column 1% is shown as a simple cylinder, it is obvious that it might, for example, have a conical or other more complex shape. Similarly, although the axis of inlet 11 is shown as perpendicular to the axis of the column, it might be at some other angle thereto, e.g. canted upwardly or downwardly; also, there may be more than one semitangential entrance at the same elevation, or at difierent elevations.

The column 19 has a false bottom 9, through which extends a central riser 8. The riser 8 terminates just below the inlet 11.

A line 14 is provided for carrying hot solids to the inlet 11. These solids are introduced into the inlet 11 by means of a carrying gas such as steam, added through line 34.

A line 1 2 is provided from introducing hydrocarbonaceous feed into the riser 8. A carrying gas may be added to the feed, if desired, through a line 13.

Adjacent to the shell 14) is located a burner This may have any desired construction, and may, for example, have a semi-tangential inlet a. A line 28 is provided for conveying solids from the bottom of the shell 10 to the inlet 30a. Air and supplementary hot line gas, as required, are added through line 29. A line 31 is provided for removing flue gases from the burner. Unburned solids, collecting in a bed 32 at the bottom of the burner are delivered via the line 14 to the inlet 11 of column 10 as noted above.

At the top of the shell 10 is provided a quenching dome 16. In the interior of dome '16 a hollow quenching fluid distribution device 17 is suspended by means of struts 18. The construction of this dome and the distribution device is considered to be novel and advantageous in preventing deposition of tars and the like. Details of this construction are shown more clearly in FIG. 2.

Referring now to FIG. 2, the distributor 17 is generally conically shaped. Its conical upper wall 2% may be constructed out of any desirable material such, for example, as stainless steel. Its lower wall 36 is constructed of a porous refractory material. There are many suitable porous materials of this nature on the market such, for example, as Aloxite, an alumina base material manu factured by the Carborundurn Company, of Niagara Falls, New York, and porous stainless steel of the type made by the Pall Filtration Company, of Glen Cove, New York.

The column 10 has an extension 37 which comes up into the dome 16, the distributor 17 and the extension 37 being so situated with respect to one another as to provide a relatively narrow passage 38 through which the gases ascending in the column 10 must pass in order to reach the interior of the dome 16. The extension 37, like the lower wall of the distributor 17, is constructed of a porous refractory material. It is, moreover, made hollow so that a generally annular passage 39 is provided around the top of the column 10.

A line 19 is provided through the top of the dome 16 for discharging a quenching medium such as oil at the apex of the conically shaped distribution device 17. The oil flows down along the upper wall 20 of the device 17 and forms a curtain 21 through which the gases moving through passage 38, must pass.

A gutter 22 is provided at the lower edge of the dome 16 to collect liquid, and a line 23 is provided for removing the collected liquid through a line 23. Gaseous materials are drawn oil from the top of the dome through a line 24.

A line 40 having two

branches

41 and 42 is provided for carrying an inert gas into the interior of the distributor l7 and into the annular passage 39.

In operation, hot solids at say 950 F. to 2700" F. are carried from a bed 32 in burner 30 through line 14 by means of an inert carrying gas such as steam introduced through a line 34. The solids are delivered to the inlet 14 where they meet a relatively high velocity, say 10 to ft./sec. stream of an inert gas introduced through line 7. This creates a vortically moving mass 15 of hot solids in the shell 10.

Hydrocarbonaceous feed, e.g. butane, is introduced into the riser 3 via line 12. This material enters the vortically moving mass of high temperature solids axially. Upon contacting the hot solids in mass 15, the feed is vaporized and converted to form a variety of products, depending on the conditions of reaction and the type of feed. The solids, being thrown outwardly by the vortical motion of the mass, slide down along the walls of the column,

10 and are thus separated from the gaseous products of conversion which move overhead. The solids form a bed 6 in the bottom of column 10. A stream of solids is drawn from this bed 6 and conveyed via line 28 to the burner 30 where combustion takes place, and it may be in part burned, to heat up the unburned .remainder which forms the bed 32. Solids in excess of the system requirements are removed via line 35.

The gaseous products of conversion move upwardly into the dome 16. An innocuous gas, e.g. steam, is introduced into the interior of distributing device 17 and passage 39 via line 40 and its

branches

41 and 42. This steam is maintained at a higher pressure than the products of conversion coming up through column 10, the pressure diiierential being between about 0.1 and about 15 psi. Steam therefore passes through the porous walls 35 of the device 17 and the walls of the passage 39 at a velocity between about 2 and about 300 ft./sec. Thus a film of steam is formed on the outer surfaces of those walls and deposition of products of conversion on the walls is avoided.

Alternatively, steam may be sent through

lines

40, 41 and 42 intermittently. This causes the steam to pass through the porous walls of the device 17 and passage 39 intermittently, knocking otf deposits that may have formed thereon.

The products of conversion pass through passage 38 between device 17 and extension 37 and meet the curtain of quench fluid 21. They are thereby quenched. The quenching fluid with condensed and absorbed products of conversion gathers in gutter 22 whence it is removed through line 23. Uncondensed and unabsorbed gases are removed through line 24.

The system which has just been described presents the present invention in its simplest form. As such, it is suitable for various reactions with fluid hydrocarbonaceous materials in which a relatively short contact time, i.e. on the order of 2.0 seconds or less, is desirable. Such reactions are exemplified by the pyrolytic conversion of light hydrocarbons, e.g. isobutane, into more valuable products, and by the catalytic conversion of gas oils into fuel gas. Needless to say the temperature, pressure and other'reaction' conditions employed will vary with the particular feed and the reaction it is desired to carry out. These conditionsare well known to the art and are not considered to be a part of the invention.

Where it is desired to use the invention in processes requiring more extended reaction times it is preferred to combine the single, vortically moving mass characteristic of the present invention with one or more other conversion stages. These other conversion stages may comprise further vortically moving masses, or more conventional systems, such as elongated tubes or fluidized beds. A system which combines a vortically moving mass with both, a fluidized bed and an elongated tube, is shown in FIG. 5. This system is particularly suitable for the pyrolytic conversion of heavy hydrocarbons, e.g. Bunker C fuel oil, into unsaturated materials, such as acetylene or butadiene.

ReferringtoFIG. 5, the system shown therein comprises a first stage gasifier 100 which in turn comprises a vertical tube 101 having a lower extension 102. At the top of the tube 101 is located a conically shaped vessel 103 which serves as a second stage gasifier. The tube 101 empties into this vessel 103. In the lower portion of the vessel 103' is located a grid 104 adapted to support a bed of fluidized solids 105. A downcomer 106 having a funnel-shaped head 107 extends from above the level of the bed 105 down through the vessel 103 and tube 101 into the extension 102. At the top of the vessel' 103 is located a column 108 which serves as a third stage gasifier. The column 103 is provided with a semi-tangential inlet 109 and is topped by a dome 110 containing a quenching liquid distributor 111. The construction of the dome 110' and distributor 111 is similar to'that described above in connection with FIGS. 1 and 2. A line 112 is provided for removing gaseous products of pyrolysis and a line 113 is provided to remove liquid products of pyrolysis from the dome 110.

Adjacent to the column 108 is a burner 114. This burner m-ay'be of any'conventional construction adapted for the combustion of finely divided solids but is preferably a substantially cylindrical column 115 having a semitangential inlet 116. A line 117' is provided for conveying solids from the burner 114- to the inlet 109 of column 108. A line 118 is provided for conveying solids from the burner 114 to the top of the funnel 107 of the downcomer 6. A line127 is provided for conveying solids from the bed 105 to the inlet 116 of the burner 114.

Theconstruction of the bottom portion of the first stage lgasifier 100 is shown in greater detail in FIG. 6. As pointed out-in the opening of the specification it has been difiicult in prior systems to entrain solids in a moving stream of gases under conditions such that the weight ratio of solids to gases is substantially constant with time. The construction shown in FIG. 6 is designed to achieve this. The solids which have been put in the downcomer 107 fall in the extension 102 of the tube 100. These solids are fluidized by means of a fluidizing gas such as steam for which lines 119 are provided leading into the extension 102. The mass of fluidized solids 'flows up through the extension 102 and on to the floor 120 of the column 101. This floor is perforated in a number of points 121 and additional fluidizing gas is furnished through a line 122 to these points to maintain a bed of fluidized solids 123 on top of the floor 120.

Liquid hydrocarbonaceous material, e.g. Bunker C fuel oil, is delivered through a line 124 into a series of nozzles 125 which are located in recesses 126 in the floor 120. The liquid hydrocarbon is atomized by means of the nozzles 12S and the droplets are brought into contact with the hot fluidized solids in the bed 123. The liquid is thereby vaporized and moving upwardly through the bed at a'relatively high velocity, entrains solids from the bed and carries them up through the tube 101. Because the bed 123 is at a relatively constant temperature and because solids are delivered at a constant rate to each jet of liquid as it comes from the nozzles 125, the stream of vapors and entrained gases which enter the tube 101 is of relatively constant quality both as respects the solids/ gas ratio and'the temperature.

Turning now to the overall functioning of the system shown in FIG. 5, liquid hydrocarbonaceous material is introduced through the line 122 into the bed 123 in the manner indicated. The bed 123 is composed of non-catalytic particles maintained at a temperature between about 1000 F. and about 2000" F. The liquid feed is thereby volatilized and the resulting gases move up out of the bed 123, entraining solids as they leave. The gases and entrained solids move upwardly through the tube 101. The temperature of the combined stream moving upwardly through tube 101 is between about 900 F. and

l50=0 F. preferably between about 1000 F. and about- 1300 F. Pressure is say 3 p.s.i.a. to p.s.i.a. The total contact time between injection of the feed and passage through grid 104 is between about 0.1 and about 5 seconds, perferably 0.5 and 2 seconds. The combined stream moves through the grid 104 and enters the vessel 103. The greatly enlarged diameter of the vessel 103 reduces the velocity or" the gases and a fluid bed forms above the grid 104. The temperature of the bed is somewhat lower than that in the reaction tube, say 800 F. to 1380 F., usually 950 F. to 1250 F. Pressure is between about 2. p.s.i.a. and about 98 p.s.i.a. Residence time is 05-20 seconds, preferably between about 2 and about 5 seconds. Thus the fluid bed provides the residence time necessary for the initial pyrolysis reactions to be completed. The initial products of pyrolysis pass out of the top of the bed and into the column 108.

Solids from burner 114 at say 1400-3000" F. are introduced semi-tangentially into the column 108 through inlet 109 by means of a carrying gas furnished through line 132. These hot solids form a vortically moving mass 133 in the column 108. The initial products of pyrolysis moving up through the column 108 add a vertically moving component to the stream entering through the inlet 109 and push the mass 133 above the inlet. In passing through the mass the initial products of pyrolysis from bed 105 are further pyrolyzed to form unsaturated materials such as butadiene and acetylene, the precise product depending on the temperature and on the initial reactants. In the mass 133 the pressure may range from say about 2 p.s.i.a to about 100 p.s.i.a. The products immediately enter the dome and are quenched as described above, so that further reaction is prevented and good yields of unsaturates are obtained. The total reaction time between entering the mass 133 and quench is on the order of 0.01 to 2.0 seconds, normally from 0.1 to 0.5 second.

The solids introduced into column 10 8, fall downwardly along the walls of the column and into funnel 107 where they are used in the first pyrolysis stage.

The hot solids furnished to the column 108- originate in bed 105. They are drawn therefrom via line 127 and conveyed to the burner 114 by means of a carrying gas introduced at 127a. They enter the burner semi-tangentially via inlet 116. Air and supplementary hot flue gas, as required, are furnished through line 129 and the solids are burned in part in a vortically moving mass. Products of combustion are removed through line 131 and heated unburned solids are removed from a bed 130' in the bottom of the burner 114.

It will be understood that the solids used in the process described may be basically carbonaceous, e.g. char or coke produced in the carbonization reaction, or non-carbonaceous, e.g. sand or alumina. If the solids are basically carbonaceous and an excess of char or coke is produced during the reaction, over and above the heating requirements of the process, this may be Withdrawn through line 128. If the solids are basically non-carbonaceous it is normally preferred to burn ofl all the carbon or carbonaceous residue deposited thereon during the pyrolysis, in the heater 114.

In some instances the solids falling down into the funnel 167 from column 168 may not be adequate in quantity or temperature to carry out the primary pyrolysis stage. To compensate for this, additional solids may be brought from burner 114 via line 118 and dumped into the funnel.

The system of FIG. is particularly adapted to the conversion of liquid hydrocarbons into highly unsaturated materials such as butadiene and acetylene. In particular, the vortically moving bed technique is especially suitable for the terminal pyrolysis stage because the contact time in the bed can be made very short and the products can be delivered directly from the bed to a quenching device without passing through an intermediate separator. If a gaseous heat transfer media were used in place of this vortically moving bed, large quantities would be required to furnish the amount of heat necessary. If, on the other hand, hot solids were used in some technique other than the vortically moving bed either the solids would have to be quenched along with the products which would entail undesirable loss of heat or else a further separation device constructed of expensive refractory material would be required.

It will be understood that the technique of dispersing solids into a vapor stream disclosed above, particularly in connection with FIG. 6, may be used in various systems and is not limited to the particular system described or, indeed, to any pyrolysis system. It is of general applicability.

It has already been mentioned that the present technique may be applied to the low temperature carbonization of coal. A suitable system for this application is shown in FIG. 7. Referring to FIG. 7, the system shown therein comprises a preoxidizer 50, a carbonizer 51, a cracking unit 52 and a heater 53. The heater 5:: is located directly above the preoxidizer 50 and the cracking unit 52 is located directly above the carbonizer 51.

The preoxidizer comprises a vertical column 54 having a generally tangential inlet 55. The upper portion 56 of the preoxidizer column 54 extends into the bottom of the heater 53. The heater 53 is a column of somewhat larger diameter than tthe column 54. It has a semi-tangential inlet 57 and a lower portion 58 of enlarged diameter. The upper portion 56 of the preoxidizer column 54- and the lower portion 58 of the heater 53 form an annular space 59 between them. A line 84 is provided for conveying solids from the space 59 to the preoxidizer inlet 55.

The carbonizer 5'1 and the cracking unit 52 form a single column which may be indicated generally as 6-9. An annular compartment 61 is positioned about midway along the column 60 and in fact marks the division between the carbonizer 51 and the cracking unit 52. A defiector plate 6?. is located at the top of the carbonizer 51 and serves to direct solids falling downwardly along the walls of the cracking unit 52 into the annular compartment 61. The carbonizer 51 is provided with a semitangential inlet 63 and the cracking unit 52 is provided with a semi-tangential inlet 64. A line 65 is provided for conveying solids from the bottom of preoxidizer 50 to the inlet 63 of the carbonizer 51. A line 66 is provided for conveying solids from the compartment 61 to the inlet 63 of the carbonizer 51. A line 67 is provided for conveying solids from the compartment 59 to the inlet 64 of the cracking unit 52. A line 68 is provided for conveying solids from the bottom of the carbonizer 51 to the inlet 57 of the heater 53.

At the top of the cracking unit 52 is located a dome 69 having a quenching distributor 7 0 of construction similar to that described above in connection with FIGS. 1 and 2. A line 71 is provided for furnishing quenching fluid to the dome 69. A line 72 is provided for removing gaseous products of carbonization and a line 73 is provided for 10 removing condensed and absorbed products from the dome 69.

In operation, coal is introduced into the preoxidizer inlet through a line 74. Hot char is introduced through line 84. The coal and char are picked up by a mixture of air and steam entering through a line 75. A vortical mass is formed in the preoxidizer 5t} and the coal is preoxidized, heat being furnished by oxidation and by the sensible heat of the hot char. This treatment is in accordance with well known principles of the art and prevents agglomeration of the coal when it is subsequently raised to carbonization temperature. The temperature of the coal in the preoxidation treatment is between about 400 F. and 650 F., the necessary heat being furnished by the hot char and by combustion of a portion of the coal. Pressure is between about 2. p.s.i.a. and about 100 p.s.i.a. Residence time in the mass is between about 0.01 and 2.0 seconds. The weight ratio of oxygen fed in line to coal fed in line 74 is between about .01 and about .50.

The gases resulting from preoxidation move upwardly through the column 54- and enter the heater 53. The preoxidized coal settles in a bed 76 at the bottom of the column 54. It is drawn off through the line 65 and delivered to the inlet 63 of the carbonizer 51. The necessary carrying gas may be furnished to the line 65 through a line 77. Additional carrying gas may be furnished to the inlet 63 by a line 78. As the coal from the preoxidizer 50 passes through the inlet 63 it picks up hot char delivered from the compartment 61 through line 66. This char is at a temperature between about 1300 F. and about 1650 F. The combined stream of hot char and preoxidized coal forms a vortically moving mass in the carbonizer 51. The proportion of hot char is such as to raise the temperature of the total mass to between about 700 F. and about 1050 F. The coal is thus carbonized. Most of the carbonization occurs in the vortical mass, but a certain amount of the carbonization product is developed as the coal moves downwardly through the carbonizer 51 below the vortically moving mass and into the bed 78 which forms at the bottom of the carbonizer. Char is drawn off from the bed 78 through a line 68 and is delivered to the inlet 57 of heater 53 along with air or oxygen furnished through line 79. Carrying gas for this transportation is furnished through line 82. In the heater 53 a vortically moving bed forms and a portion of the char is burned. Gas from the preoxidizer 51 which has some fuel value ascends into the heater 53 and is also burned. This results in a heating of the unburned remainder of the char. It will be understood that in some instances it will be desirable to burn supplemental gas or liquid fuel in the heater 53, which will be useful to start the process, and may be desired to act as a pilot flame or to stabilize the flame as, for example, when the air or solids fed to the burner are at a relatively low temperature.

The unburned solids fall down along the walls of the heater 53 and are deflected into the annular space 59 where they form a bed 39, which may be aerated or fluidlzed by air, as desired. =Hot solids from the bed 80 are drawn off through a line 67 and are injected through inlet 6 into the cracking unit 52 by means of carrying gas introduced at 83. The solids at the point of injection are between about 1500 F. and 1850 F. They forma vortically moving bed and into this bed is introduced axially upwardly the gaseous carbonization product from the carbonizer 51. The products of carbonization are thus further pyrolysed and by this means the proportion of valuable aromatics is substantially increased and the value of the ultimate product appreciated.

The products from the cracking unit 52 move upwardly into the dome 69 where they are quenched with oil introduced through line 71 in the manner indicated above with respect to FIGS. 1 and 2. Liquid product is removed through line 73. Fixed gases are removed through line 72.

Normally there will be an excess of char created in 1 1 the carbonizer 51 over and above that necessary for the heat requirements of the process. T his product char may beremoved through a line 81 or from other points in the process if chars of somewhat different volatile matter content are desired.

Although the process has been described as applied to a low temperature carbonization system in which the primary products of carbonization are further cracked, it is obvious that the cracking unit in this process can be dispensed with where it is desired to recover primary carbonization products as such.

The invention will be further illustrated by means of the following specific examples.

Example I Using the apparatus of FIG. 1, isobutane is introduced as feed through line 12, and finely divided solids consisting of Alundum particles dispersed in steam are introduced through semi-tangential inlet 11 at a temperature of 1500 F. The axial velocity of the gases below inlet 11 is about 25 ft./sec. and the velocity in inlet 11 is about 80 ft./sec. The pyrolysis product issuing from passage 38 is at about 1350 F. It is quenched with water introduced through line 19. .The pressure in the column is about p.s.i.a. Steam at p.s.i.a. is introduced into quenching device 17 and passage 39 (FIG. 2) and efiectively prevents deposition of tarry products. The products of the isobutane pyrolysed have the following approximate composition by volume:

Vol. percent H 40 CH 8 C H 2 1C4H8 Other 4 Example 11 Wt. percent of charge oil Fuel gas 77 Liquids 23 Example 111 1000 barrels per hour of a Bunker C fuel oil are introduced into the system of FIG. 5 through line 124, and vaporized and partially pyrolysed by means of hot fluid coke from downcomer 106 at a temperature of 1250 F. Hot coke-and steam at a temperature of 1800 F. from heater 114 are introduced to column 108, the velocity in the inlet 109 is about 100 ft./ sec. The gasiform products arising from bed 105 are heated to about 1500 F. in the mass 133. Within a totalcontact time of 0.1 second the solids have separated out and the products are quenched. 605,000 pounds per hour of products of pyrolysis are obtained, having the following approximate analysis:

Wt. percent Oil gas '41 Aromatic distillates 27 Pitch 32 12 The aromatic distillates have at least 25% resin formers and the pitch has a Conradson carbon content of greater than 50%.

Deposition of pitch on the column extension and on the distribution device 111 is effectively prevented by making these elements of Aloxite and by introducing steam at 20 p.s.i.a. into the interior of both elements in the manner described above, the pressure in the column 108 being about 15 p.s.i.a.

Example IV Using the system of FIG. 7, 100,000 lbs/hr. of bituminous coal are introduced into the p-reoxidizer 50 via inlet 55. Along with the coal are introduced 49,000 lbs/hr. of char at 1600 F. from line 84 and 10,000 lbs./ hr. of air. The velocity in the inlet 55 is 50 ft./sec. The preoxidized coal collecting in bed 76 is at about 580 F. It is delivered to inlet 63 where it is mixed with 114,000 lbs/hr. of char at about 1480 F. and introduced into carbonizer 51 at 50' ft./sec. Gasiform products of carbonization at 950 F. are removed upwardly in carbonizer 51 and are contacted with hot char. This char is introduced through inlet 64 at about 80 ft./sec. and 1600 F. Cracked products are removed from cracking unit 52 at about 1450 F. and are promptly quenched to 600 F. by oil introduced through line 71.

The gasiform products of pyrolysis removed overhead from cracking unit 52 have the following analysis:

Wt. percent Coal gas 70 Liquid 30 The liquids contain less than 10% non-aromatics.

Seventy thousand (70,000) lbs/hr. of char having a volatile content of 8.5% are recovered at 81.

This is a continuation of my copending application Serial No. 722,195, now abandoned.

What I claim is:

1. In a system for the conversion of hydrocarbonaceous materials comprising a pyrolysis zone, the improvement which comprises a quenching dome, duct means leading upwardly from said pyrolysis zone to said dome and having a hollow extension inside said dome, said extension having porous walls, a hollow distribution device positioned in said dome above said duct means, said distribution device having a conical upper wall and a porous lower wall, said walls having inner and outer surfaces, the lower wall of said device and said extension forming a passage leading from said duct to the interior of said dome, means for delivering a quenching fluid to the upper surface of said distributing device, whereby a curtain of quenching fluid is formed around the edge of said upper wall and means for introducing an innocuous gas under pressure to the interior of said hollow device and the interior of said hollow extension, whereby deposition of product on said extension and the lower wall of said device is avoided.

2. The system claimed in claim 1 wherein the pyrolysis zone comprises a pyrolysis chamber adapted to contain a vertically moving disperse phase mass of solids and gases, means for introducing hydrocarbonaceous material into said chamber and means for introducing a gasiform stream containing entrained hot solids semi-tangentially into said mass.

References Cited in the file of this patent UNITED STATES PATENTS 1,432,170 Fenton Oct. 17, 1922 1,955,041 Woidich Apr. 17, 1934 2,340,930 Campbell et a1. Feb. 8, 1944 2,370,816 Schonberg Mar. 6, 1945 (Other references on following page) 13 UNITED STATES PATENTS Gary Dec. 16, 1947 Smith Dec. 11, 1951 Martin Jan. 15, 1952 Lee et a1 Sept. 28, 1954 Kearby et a1 Sept. 27, 1955 Forkel Jan. 3, 1956 Brown Aug. 21, 1956 Blanding Oct. 9, 1956 14 Gomory Nov. 6, 1956 Boisture Jan. 8, 1957 Jahnig Sept. 2, 1958 Smith Dec. 2, 1958 Marshall et a1 June 2, 1959 Wickham et a1. June 16, 1959 FOREIGN PATENTS Great Britain Oct. 26, 1939

Claims

1. IN A SYSTEM FOR THE CONVERSION OF HYDROCARBONACEOUS MATERIALS COMPRISING A PYROLYSIS ZONE,M THE IMPROVEMENT WHICH COMPRISES A QUENCHING DOME, DUCT MEANS LEADING UPWARDLY FROM SAID PYROLYSIS ZONE TO SAID DOME AND HAVING A HOLLOW EXTENSION INSIDE SAID DOME, SAID EXTENSION HAVING POROUS WALLS, A HOLLOW DISTRIBUTION DEVICE POSITIONED IN SAID DOME ABOVE SAID DUCT MEANS, SAID DISTRIBUTION DEVICE HAVING A CONICAL UPPER WALL AND A POROUS LOWER WALL, SAID WALLS HAVING INNER AND OUTER SURFACES, THE LOWER WALL OF SAID DEVICE AND SAID EXTENISION FORMING A PASSAGE LEADING FROM SAID DUCT TO THE INTERIOR OF SAID DOME, MEANS FOR DELIVERING A QUENCHING AFLUID TO THE UPPER SURFACE OF SAID DISTRIBUTING DEVICE, WHEREBY A CURTAIN OF QUENCHING FLUID IS FORMED AROUND THE EDGE OF SAID UPPER WALL AND MEANS FOR INTRODUCING AN INNOCUOUS GAS UNDER PRESSURE TO THE INTERIOR OF SAID HOLLOW DEVICE AND THE INTERIOR OF SAID HOLLOW EXTENSION, WHREBY DEPOSITION OF PRODUCT ON SAID EXTENSION AND THE LOWER WALL OF SAID DEVICE IS AVOIDED.