US2585984A

US2585984A - Pebble heater apparatus and method for heat exchange

Info

Publication number: US2585984A
Application number: US666767A
Authority: US
Inventors: Alexander Cruzan; Harris A Dutcher
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1946-05-02
Filing date: 1946-05-02
Publication date: 1952-02-19
Anticipated expiration: 1969-02-19

Description

Feb- 19, 1952 c. ALEXANDER ETA. 2,585,984 'u PEBBLE HEATER APPARATUS AND METHOD FOR HEAT EXCHANGE Filed May 2, 1946 CRUZ-AN ALEXANDER HARRIS A. DUTCHER lex/WW2? M ATTORNEYS Patented Feb. 19, 1952 assassi PEBBLE HEATERAPPAATUS AND METHOD FOR HEAT EXCHANGE Cruzan Alexander and Harris A. Dutcher, Bartlesville, Okla., assignors to Phillips Petroleum Company, a corporation `oi. Delaware Application May 2, 194'6, serial No. 666,767

19 Claims.

This invention relates to the treatment of uids. In one particular aspect this invention relates to pebble heaters for the heating of gases to hightemperatures. In still another aspect this invention relates to a method and apparatus for heating hydrocarbons t rel-atively high temperatures for conversion thereof to other hydrocarbons and hydrogen-containing gases. Another aspect of this invention relates to a reaction chamber and a method for heating the same.

In hydrocarbon conversion processes which require high temperature and which are endothermic in character, such as thermal cracking and thermal dehydrogenation of hydrocarbons, pebble heater type apparatus functions most satisfactorily. Also in the superheating of gases, such as steam, pebble heaters may also be applicable. The pebble heater methods entail the heating of refractory pebbles in a heating chamber by the combustion of fuels and the transference of resulting- `hydrocarbons to produce lighter products, the

pebbles leaving the cracking chamber are still at a very high temperature and can be handled in mechanical conveyor equipment only if high temperature alloy materials are used. Furthermore, in conventional apparatus it is difcult if not impossible to obtain the high temperatures that are so advantageous in cracking of the lighter hydrocarbons wherein temperatures of 1500 to 2000 F. or higher are often necessary. Consequently, it is highly desirable to provide a pebble heating type apparatus and reaction chamber i which requires few mechanical moving parts.

An object of the present invention is to provide ame'thod and apparatus for the attainment of extremely high temperatures in a pebble heater type furnace.

i Another object is toprovide a novel apparatus for supplying heat to or removing heat from gases.

Still another object of the present invention vis t0 provide an apparatus for heating and reacting materials in a single unitary apparatus.

7 ing the characteristics of the conventional pebble heater type furnace without the necessity of mechanical conveyors for conveying the pebbles.

It is a further object to provide a method and apparatus for heating gases with pebbles whereby large temperature changes of the pebbles are minimized.

Various other objects and advantages will become apparent to those skilled in the art from the accompanying description and disclosure.

For a full understanding of the nature and objects of invention, reference should be had to the following detailed description taken in connection with the accompanying drawing.

In the drawing- Figure l is an elevational view, partially in cross section, diagrammatically illustrating apparatus for heating a. uid according to the present invention.

Figure 2 is another modification of the present invention also shown in an elevational View, partially in cross section, illustrating apparatus for heating a fluid.

In Figure 1, which diagrammatically illustrates one arrangement of apparatus for this invention, numeral 8 designates an elongated, enclosed,

vhollow body which contains both a combustion Y zone and a heating or reaction zone. The hollow body is divided into a reaction zone 23, an intermediate zone and a combustion zone 'l by septa i8 and Il, respectively. The form of the hollow body is preferably cylindrical as a matter of convenience in both construction and operation, but hollow body 8 may be of any other particular form as desired. Hollow body 8 can be constructed of various types of metals, such as steel, nickel and chrome alloy steels, or Inconel. and,

preferably, is lined or covered both on the inside and the outside thereof by suitable materials (not shown). 'Ihe lining on the inside of cylinder 8 will usually comprise refractory material, such as those materials which are resistant to high temperatures and to spelling by the pebbles. Suitable materials for such purposes, for example, are kaolin, alumina-diaspore, sillimanite, bonded silicon carbide, bonded fused alumina, etc. The covering on the outside of cylinder 8 is usually asbestos, or the like, for preventing the loss of heat from cylinder 8. Under some circumstances cylinder 8` is constructed entirely of ceramic refractory material and may be constructed in sections, each l section of the same or different material, with- 3 of this invention, septum I8 is perforated and contains a vent or lumen, preferably in the center thereof, as shown by numeral I9. Septum I8 may be constructed of any type of material which is resistant to high temperatures and which has suilcient strength to support its own weight and the weight of a layer of pebbles on the top thereof f In some instances septum I 3 is made of a metal, such as a high alloy metal as Inconel; in other instances it is constructed of suitable ceramic or porcelain material. Usually the construction of septum I8 is of'a metal and is in the form of a perforated disc or plate, or a wire screen, so that pebbles collect on the top thereof in a layer and flow through the holes or perforations therein into chamber 25 below. Septum Il may be constructed of materials similar to those described with respect to th'e construction of septum I8. The form of septum I I, however, is somewhat different, preferably, in the form of a funnel-shaped member having a vent or opening, generally in the center thereof, for passage of uid therethrough. Septum II may also be of a relatively greater thickness (as shown) than septum Il! and capable of supporting a relatively deep layer of pebbles on the top thereof. When septum I8 is of such a relatively massive construction, it will be made of ceramic material. When septum II is constructed more or less as a thin plate or sheet in the form of a funnel or cone, it will be made of metal.

Element I3 is an elongated conduit open at both ends and is positioned concentrically to vent I of septum II. The lower end of conduit I3 terminates adjacent and above vent I6. The length of conduit, preferably, constitutes only a minor proportion of the length of the intermediate chamber and serves as a passageway for the flow of gases and pebbles from chamber 25 to reaction chamber 23. In other words, the length of conduit I3 is usually less than about one-half the length of chamber 25. Conduit I3 is supported at the proper location in chamber 25 by suitable rods or beams I4. Conduit I3 is constructed of a suitable material, such as porcelain, In-conel, or the like. Element I2 provides a restricted area in the lower end of conduit I3 and operates as a nozzle. Fuel and air are introduced through

conduits

4 and 5 into combustion chamber 'I in which combustion of the fuel and air is eected. The combustion products or flue gases pass from combustion chamber 'I through vent I5, conduit I3 into intermediate chamber 25. Flue gases are removed from intermediate chamber 25 through conduits 24. The uid to be treated or heated is passed into the lower portion of zone 23 through conduits 26 and the resulting eflluent is removed from the top of zone 23 through conduit 28 and valve 29. Element 21 is a shield or like means for deecting pebbles and preventing their passage from chamber 23 through conduit 28.

Valve 29 is a conventional motor or automatic control valve which is actuated by transmission means 3l electrically or pneumatically responsive to the pressure in intermediate chamber 25. For the various types of hook-ups of an automatic valve and its operation reference is made to the adequate description in Industrial Instruments for Measurement and Control, Rhodes, T. J., McGraw-Hill Book Company, 1941.

Septum or screen I8 is perforated with the appropriate number and size of holes to maintain a desired depth of pebbles, shown at 2|, on the septum and at the same time to permit pebblesv to fall through the perforations. Conduit I3 is located close to septum II so that pebbles accumulate on the top of septum II, as indicated by numeral 22, and simultaneously continuously oW through the annular space between septum II and the lower end of conduit I3 into the gas stream from vent I6.

Various modifications, alterations of the elements of Figure 1 may be practiced without departing from the scope of this invention. As shown, feed entering through conduits 25 is introduced in tangential direction; however, the feed may be introduced without a tangential direction if desired. Furthermore, flue gases being removed through conduits 24 may be removed in a tangential direction if desired. Vent or lumen I9 may be constructed in any form and may extend further into reaction zone 23 than shown. In some instances it may be desired and preferable to eliminate combustion zone 'I and in so doing the combustion gases and air are introduced directly through vent I6 and are burned in conduit I3. Combustion zone 1 may be a separate unit from cylinder B and the effluent from zone 'I is passed to inlet or vent I6 through suitable conduits (not shown). A screen or the like (not shown) may be placed over the top of vent I6 in order to prevent pebbles falling from zone or chamber 25 to combustion zone 1. Nozzle or restriction I2 may also be omitted if desired and conduit I3 may comprise a bundle or group of small conduits (not shown) which together comprise conduit I3.

A heat exchanger (not shown) may be provided for heat exchange of the flue gases in conduits 24 with incoming feed in conduits 26 or with air in conduits 5.

In Figure 2, which diagrammatically shows another modication of apparatus for practicing the present invention, element 53 as in Figure 1 is an elongated, enclosed, hollow body, preferably of a cylindrical shape. Cylinder 53 is separated into an upper chamber l2, a reaction chamber 'II and a combustion chamber 5l' by a perforated septum 68 and a funnel-shaped septum 59, respectively. The construction and materials are similar to those of the apparatus described in Figure 1, and, therefore, such description is unnecessary with regard to Figure 2. As in Figure l septum 68 may comprise a wire screen or the like for the collection of pebbles thereon.

A conduit 62 is passed through screen or septum 68 in open communication between chamber l2 and the lower portion of reaction chamber 'Il as shown. Conduit 62 is held in position in reaction zone 'II by means of supporting rods 66. Conduit 62 is preferably an elongated cylindrical pipe or tube and is positioned so that it protrudes through the center of septum 68 and extends substantially the entire length of chamber 'II and terminates adjacent a vent 58 of septum 59. Vent 58 is preferably located in the center of septum 59. Fuel and air are introduced into combustion zone 5l through

conduits

54 and 56, respectively. The products of combustion are passed from comvbustion zone 51 to zone 72 through conduit 62 and are removed therefrom through a conduit 14. Conduit 'I6 is a uid inlet for introduction of feed into the upper portion of reaction zone 'I I. Withdrawal of an effluent from zone 'Il is eected through conduit T8. The lower portion of conduit 62 may be restricted in cross sectional area by element 8|. Element 'I3 comprises a guard or shield for preventing the passage of pebbles from chamber l2y through conduit 14 which removes -hot gases. M Vthrough orifice or vent I6 is substantially in exthe heating uid from chamber 12.

Numerals

63 and 69 indicate the accumulation of pebbles in the lower portion of reaction chamber 'II and chamber 12, respectively.

As described 4in Figure 1, various alterations and modifications may be effected in the apparatus shown in Figure 2 without departing from the scope of this invention. Preferably, conduit 'I8 is located in the lower portion of reaction zone 'II below the accumulation of pebbles 63 therein but alternatively it may be located above the accumulation of pebbles 63. Fluid introduced into chamber 'II through conduit 'I6 passes through the accumulation of pebbles 63 and out of reaction zone 'II through conduit 'I8. Conduit 62 ex- The term pebble as used throughout the specication denotes any refractory material, either ceramic or metallic, in flowable form and size which can be utilized to carry heat from one zone to another. tially spherical and are from as large as about 1 inch in diameter to as small as will pass through a 200 mesh screen. Th-e actual size of the pebbles Will of course depend upon character of the refractory material, such as its density, and upon the gas velocity of the supporting fluid stream. In general, the pebbles must be of refractory material which will withstand temper-atures as high as the highest temperatur-e attained in the pebble heating zone. Pebbles which will withstand temf peratures within the range of about 3000 to 3500 F. are now in use and comprise highly heat resistant material, such as fused alumina. The preferred size of the pebbles when using a ceramic refractory material is about that size which will:

pass through an 8 mesh screenand willberetained on a 60 mesh screen. The pebbles themselves may comprise a ycatalytic material or may cornprise an inert material impregnated with a catalytic material for the process in which they are being used. Therefore, in many instances the pebbles will comprise a metallic catalyst or will comprise a ceramic material impregnated with a metallic catalyst. I

Operation In the operation of Figure 1, a feed which may comprise hydrocarbon reactants or an inert gas to be superheated is continuously or intermittently passed into reaction zone 23 through conduit 26. The feed material in reaction zone 23 undergoes the desired treatment and achieves the desired temperature by contact with pebbles therein. After the gas has remained in chamber 23 for sufiicient length of time to achieve the Iappropriate temperatureit is continuously or intermittently removed therefrom through conduit 28 and valve 29.

In order to heat the pebbles to a suciently high temperature to transfer heat to the gas in chamber 23, fuel and air 'enter combustion zone I through 4conduits' 4 and 5, respectively, and are burned therein. The fiue gas or combustion products from combustion zone 'l continuously pass through an orifice or vent I6 into chamber 25 and pass upward through conduit I3 at a high rate of speed as the result of the expansion of the The rate 'of flow of gases 'passing cess of the flame propagation of the combustion Pebbles are conventionally substan- :Y

` gases. Therefore according to one modification,

lrate of fiame propagation. In either of the above methods of operation, theA gases from the chamber 1 passing through conduit I3 achieve a very high rate of speed in excess of about 10 to about 15 feet per second and often as high as about 30 to about 40 feet per second, which speed depends to a large extent upon the cross sectional area of the inside of conduit I3. The high rate of speed of the gases passing from vent I6 into conduit I3 through restricted area I2 aids in continuously forcing pebbles which have accumulated at 22 into the gaseous stream by an inspirating eiect. The pebbles falling into conduit I3 are heated and suspended in the gaseous stream which throws them upward from the upper end of conduit I3 through vent IS and into upper chamber or reaction zone 23. When the pebbles comprise a catalytic material, the heating of the pebbles in conduit I3 also regenerates or reactivates the catalytic material. Because of the sudden increase in cross sectional area confining the gases when they pass from conduit I3 into the open space of chamber 25, the Velocity of gaseous stream rapidly decreases. Flue gases are removed from chamber 25 through conduits 23. However, because of the inertia and momentum of the pebbles, the heated pebbles pass upward through vent I9. In chamber 23 the pebbles lose their velocity and fall downward onto screen I8. Some of the pebbles may have sufficient velocity to impinge upon shelf 2'! which changes their direction and makes them drop onto screen I8. The size of the perforations in screen I8 with regard to the size of the pebbles and to the rate at which they accumulate is such that a layer of pebbles 2|, often several inches in thickness, is continuously maintained on the top side of screen I8. The pebbles fall through screen I8 at substantially the same rate as they accumulate thereon. The layer of pebbles 2| on screen I8 prevents or hinders the passage of gase's from reaction zone 23 to chamber 25 or vice versa; thus the intermingling of gases from each chamber is prevented or minimized. As shown the feed enters reaction zone 23 is a tangential direction tc attain a tangential motion and by this motion the feed aids in spreading out the stream of pebbles flowing from chamber 25 into chamber 23 and ensures an even distribution of pebbles on screen I8.

Mechanical means for shaking screen I8 (not shown) may be used to aid in forcing the pebbles through the perforations in screen I8 and also by controlling the amountv of shaking the height of the pebbles on screen I 8 can be adjusted.

The pebbles give up the heat acquired in conduit I3 and chamber 25 to the incoming fluid feed in reaction chamber 23. After accumulation on screen I 8 the, pebbles# continuously fall through the perforations therein and drop by gravity into .the lower `portion of chamber 25 for reheating. l

-tum Il serves as a proport'ioning device for the flow' of pebbles from chamber 25 into the high 'Ispeed gas stream from lvent I6. Y

11n-circumstances where it is objectionable or undesirable for any gases from chamber 23 to pass into chamber 25, a higher pressure may be maintained in chamber 25 than in chamber 23 by means of valve 29 and transmission means 3| responsive to the prevailing pressure in chamber 25. If a slightly excess pressure, e. g'. between about 2 and about 5 pounds per square inch difference, is maintained in chamber 23, a small amount of gases continuously flows from chamber 23v to chamber 25 through vent I9 while at the same time pebbles are passing upward from chamber 25 to chamber 23 through vent I9. The pebbles in chamber 23 which are at a very high temperature, such as about 1500 to about 3000 F.,

l give off much of their available heat before falling into lower chamber 25 where they are reheated.

Since the operation in Figure 2 in most respects is similar to the operation in Figure l, only a brief discussion of the operation of apparatus illustrated in Figure 2 will be made. Figure 2 is another modification of the present invention showing apparatus for the heating (or cooling) of gases. A uid feed enters zone 1I of cylinder 53 through conduit 15. This feed contacts falling pebbles in zone 1I and passes through the accumulation of pebbles 63 in the lower portion oi zone 1I and thence from cylinder 53 through conduit 1li which may have a screen (not shown) over the mouth thereof to retain pebbles in zone 1 I. It should be noted that in the preferred method of operation shown, the accumulation of pebbles G3 in zone 1I is such that the gases from conduit s must pass through the accumulation of pebbles before being' removed from cylinder' 53. Fuel and air are passed into combustion zone 51 through conduits 54 and 55, respectively, The combustion mixture is burned in zone 51 and thehot combustion products or ue gases are continuously passed from zone 51 through vent or orifice 58 into elongated conduit 62 through restricted area 6I. Since the fluid iiowing through vent 5S and restricted area 6I into conduit 62 is at a high velocity, pebbles fall into the liowing gaseous stream by an inspiration effect as well as by their own weight and are heated and suspended in the hot gaseous stream. In thisembodiment of the invention the gases flow in conduit 52 only at a sucient rate to suspend the pebbles and convey them along with the hot flue gases through conduit 62 to upper chamber 12. In upper chamber 12, becauseof the increased cross sectional area of that zone, the gases lose much of their velocity. The suspended pebbles fall onto screen 58, as shown. Those pebbles which may have enough velocity to pass to the upper portion of chamber 12 impinge against shield 13 and are deflected downward onto screen 68. The accumulation of pebbles on screen 63 indicated by numeral 59 prevents the passage of gases from chamber 12 to chamber 1I, as described With respect to Figure 1.

Pebbles at a relatively high temperature, e. g. 1500 to 2500" F., drop through perforations in screen 58 and fall by gravit;7 through chamber 1I to the lower portion thereof and'accumulate as indicated by 63. In chamber 1I the pebbles give up the heat acquired in conduit 62 to the feed entering through conduit 1G.

As in the case of Figure 1 combustion zone 51 may'comprise only a mixing zone and combustion may take place entirely in conduit 62 and upper chamber 12 without departing from the scope of this invention. Even in some instances zone 51 may be separate from cylinder 53 (or zone 1 from cylinder is' of Figure 1) without departing from the scope of the invention.

Aparticular novelty of the modification shown in Figure 1 lies in the fact that the pebbles from the heating zone 25 pass to reaction zone 23 by their own inertia and momentum achieved by their suspension in the gaseous stream in conduit I3. On the other hand a particular novelty of the modification shown in Figure 2 lies in the fact that the pebbles accumulating in reaction zone 'II are passed therefrom by being supported in a gaseous stream in conduit 62 throughout their passage from zone 1I to upper zone 12. For the operation of Figure l a higher velocity of gases must be maintained in conduit I3 than is usually maintained in conduit 62 of Figure 2, because in Figure 1 the pebbles are passed to the upper zone 23 by force of their inertia and momentum While in Figure 2 the pebbles are passed into upper zone i2 by a suspension or gas lift effect. Although Figure 2 comprises the preferred modification of the present invention, in some instances it may be more desirable and more practical to use the type of apparatus and method shown in Figure I.

The feed entering cylinder 53 through conduit 15 of Figure 2 may be introduced tangentially as in the case of Figure 1. Furthermore, the feed of Figure 2 may be introduced through conduit 'I3 and the resulting product removed through conduit 15 without departing from the scope of this invention.

It is possible in some instances to operate zone 23 of Figure 1 as the combustion zone for heating the pebbles and zone 25 and conduit I3 as the reaction zone. Thus, the reactant gases are introduced into zone 25 through inlet I6 and are removed therefrom through conduits 24. Air and fuel are introduced into zone 23 through lines 26 and a flue gas is removed through line 28. The reactantgases themselves suspend the pebbles in conduit I3 according to this modification.

The present invention may be applied to exothermic reactions as well as endothermic reactions. For example, feed introduced through conduits 54 and 5S in Figure 2 may undergo an exothermic reaction in chamber 51. The reaction efiuent passes from zone 51 through conduit 62 at a rate such that cool pebbles are supported therein and absorb heat from the reaction effluent. The pebbles are then discharged from conduit 52 into zone 12 where they drop back into cooling zone -1I, as shown, but at a substantially higher temperature than when introduced into conduit 62. The pebbles then give up their heat in cooling zone 1I and pass downward to absorb heat from the reaction eiluent passing through conduit 52. The cooling medium is introduced into cooling zone 1I through conduit 1t or 18 and removed therefrom through conduit 18 or 16. This and many other modifications may be pracd ticed without departing from the scope of this invention in either the apparatus shown in Figure 1 or in Figure 2.

Various advantages of the present invention are apparent. Pebble heaters constructed in the manner described in this application do not have the conventional pebble conveying equipment. The pebbles are transferred according to this invention from one zone to another without the usual mechanical conveyor. Other usual mechanical features of pebble heaters are also eliminated, such as star valves, conduits, throats, etc. Furthermore, the pebble heater itself is unitary which enables economical construction and opof steam and as a typical example of such a process the following application will be described. A power unit requiring approximately 1000 pounds of steam per hour at a temperature of about 1000 F. utilizes the apparatus of Figure 2 in the lfollowing manner. Steam is passed through chamber 'H at the rate of a-bout 1000 pounds per hour at a pressure of about 20 pounds gage and at an entrance temperature of about 280 F. The steam in a superheated condition leaves zone 'il through conduit 13 at about 1000 F. A hydrocarbon fuel, such as butane, is burned in zone 51 with excess air. The flue gas from combustion zone 51 passes through a 3 inch diameter conduit 62 at a rate of about 30 feet per second. The pebbles of quartz or sand used for such operation preferably have a diameter of about 0.006 of an inch and are readily suspended in the fluid in conduit 62 and are heatedv above about 1500 F. The diameter of conduit 62 is about 3 inches inside diameter and the diameter of cylinder 53 is about 2 feet. Conduit E2 is about 4 to `6 feet in length depending upon the depth of the pebbles accumulating in reaction zone ll.

The apparatus and method for heating gases as described in this application may be used for various other processes than those speciiically mentioned. Other chemical reactions to which the present invention is applicable comprise dehydrogenation of hydrocarbon, the formation of water-gas from hydrocarbons and steam, the hydrogenation of carbon monoxide, depolymerization and dealkylation, etc.

It is to be understood that the form of our invention herewith shown and described is to be taken as preferred example of the same, and that various changes in shape, size and arrangement of parts may be resorted to without departing from the spirit of this invention or the scope of the subjoined claims. v

Having described our invention, we claim:

, 1. Apparatus for the treatment of a gas which comprises in combination an enclosed, hollow body having an outlet at the top thereof and an inlet at the bottom thereof, a iirst perforate septum having a vent for the passage of gas therethrough positioned across said hollow body and forming an upper chamber in said body, a second imperforate septum having a vent for the passage of gas therethrough positioned across said hollow body so as to form a lower chamber below said second septum and an intermediate chamber between said iirst and second septa, means l for introducing a gas into said upper chamber,

means for removing gas from said intermediate i chamber, and a conduit positioned in said intermediate chamber in vertical alignment with said vents and in close spaced-apart relation to the vent in said second septum.

2. Apparatus for the treatment of gas in the presence of pebbles which comprises in combination a vertical elongated enclosed vessel having an outlet at the top thereof and an inlet at the bottom thereof, a rst perforate septum having a vent for the passage of pebbles therethrough positioned across said vessel so as to form an up-` per chamber therein, a second imperforate sepg tum having a vent for the passage of gas therethrough positioned across said vessel so as to form a lower chamber below said second septum and an intermediate chamber between said rst and second septa, means for introducing gasinto said upper chamber, means for removinggas from said intermediate chamber, and conduit means aligned with said vents and extending upwardly from close proximity to the vent in said second septum adapted for lifting pebbles by means of high velocity gas to said upper chamber.

which comprises in combination an upright enclosed cylindrical vessel having a gas outlet at the top and a iiuid inlet at the bottom thereof, a first perforate septum positioned in said vessel whereby an upper chamber is formed in said body,

Ia second imperforate septum having a central vent for the passage of gas therethrough positioned in said vessel so as to form a lower chamber below said second septum and an intermediate chamber between said first and second fsepta, an elongated conduit openly communicating between said upper chamber and said intermediate chamber passing through the center of said irst septum and extending downward and terminating in close spaced-apart relation to the vent in said second septum so as to effect the passage of pebbles from the bottom of said intermediate chamber into and through said conduit to said upper chamber upon the passage of an upward blast of gas through said vent into said conduit, means for introducing feed gas into said intermediate chamber, and means for withdrawing eliluent gas from said intermediate chamber.

4. Apparatus for the treatment of a gas which comprises in combination an enclosed upright vessel having an outlet at the top thereof and an tum and an intermediate chamber between said K rst and second septa, a conduit openly communicating between said upper chamber and said intermediate chamber passing through said rst septum and extending downward and terminating directly over but spaced apart from said vent in said second septum, means for introducing gas into said intermediate chamber, and means for withdrawing gas from said intermediate chamber.

5. Apparatus for the treatment of a gas in the presence of pebbles which comprises in combination an enclosed upright vessel having an outlet at the top thereof and an inlet at the bottom thereof, a first perforate septum having a central vent positioned in said vessel so as to form an upper chamber therein, a second imperforate septum having a vent for the passage of gas therethrough positioned in said vessel so as to form 'a lower chamber below said second septum and an intermediate chamber between said first and second septa, means positioned in said vessel for transferring pebbles from the lower portion pf said intermediate chamber to said upper chamber comprising a tube element aligned with said vents in spaced-apart relation to the vent in said second septum, means for introducing feed gas into said intermediate chambenand means for4 withdrawing eiiiuent. gas from said intermediateY chamber.

3. Apparatus for the heat exchange of gases 6. Apparatus for the heat exchange of gases in the presence of pebbles which comprises in combination an upright elongated cylindrical vessel having a gas outlet at the top and a gas inlet at the bottom thereof, a rst perforate septum having a central vent for the passage of pebbles upwardly therethrough positioned across the upper portion of said vessel and forming an upper chamber therein, said septum being adapted for uniformly passing pebbles downwardly over the area thereof while maintaining a multiple layer of pebbles thereon, a second imperforate funnelshaped septum having a central vent for the passage of a hot gas therethrough positioned across theY lower portion of said vessel so as to form a lower chamber below said second septum for the combustion of fuel therein andv an intermediate chamber between said first and second septa, means for introducing' gas tangentially into the lower portion of said upper chamber, means for removing gas from the upper portion of said intermediate chamber, an elongated open conduit positioned in said intermediate chamber in alignment with said ventsV and extending from adjacent the vent in said second septuml only a portion of the length of said intermediate chamber, said conduit havingy a restricted opening in the lower end thereof and being positioned so as to effect the passage of pebbles from the bottom of said intermediate chamber into and through said conduit and said intermediate chamber to said upper chamber upon passage of an upward blast of gas through said Vent in said second septum into said conduit.

7. The apparatus of claim 6 in which said conduit extends only a minor portion of the length of said intermediate chamber.

8. Apparatus for the heat exchange of gases in the presence of pebbles which comprises in combination an upright elongated cylindrical vessel having a gas outlet at thetop and a gas inlet at the bottom thereof, a first perforate septum having a central vent for the passage of pebbles upwardly therethrough positioned across the upper portion of said vessel and forming an upper chamber therein, said septum being adapted for uniformly passing pebbles downwardly over the area thereof while maintaining a multiple layer of pebbles thereon1 a second imperforate funnelshaped septum having a central vent for the passage of a hot gas therethrough positioned across the lower portion of said vessel so as to form a lower chamber below said second septum for the combustion of fuel therein and an intermediate chamber between said first and second septa, means for introducing gas tangentially into the lower portion of said upper chamber, means for removing gas from the upper portion of said intermediate chamber, and an elongated open conduit positioned in said intermediate chamber in alignment with said vents and extending from adjacentv the vent in said second septum only a portion of the length of said intermediate chamber, said conduit having a restricted opening in the lower end thereof and positioned so as to effect the passage of pebbles from the bottom of said. intermediate chamber into and through said conduit and said intermediate chamber to said upper chamber upon the passage of an upward blast of gas through said vent in said second septum into said conduit.

9. Apparatus for the. heat exchange of fluids in the presence of pebbles which comprises. in combination an upright closed cylindrical vessel having a gas outlet' at the top and a gas inlet at the bottom, a first perforate septum positioned in the upper portion of said vessel forming an upper chamber therein and adapted for gradually passing pebbles therethrough over the entire crosssection of said vessel while maintaining a substantial layer of pebbles thereon, a second funnel shaped imperforate septum having a vent in the center for the passage of gas therethrough and positioned in the lower portion of said vessel so as to form a lower chamber below said second septum for the combustion of fuel therein and an intermediate chamber between said rst and second septa, an elongated conduit extending from the lower portion of said upper chamber through said rst septum and terminating in said intermediate chamber directly above and Iadjacent said vent so as to effect the passage of pebbles from the bottom of said intermediate chamber into and through said conduit to said upper chamber upon the passage of an upward blast of gas through said vent into said conduit, means for introducing feed gas into the upper portion of said intermediate chamber, means for withdrawing efrluent gas from the lower portion of said intermediate chamber, and means for preventing the passage of pebbles through said outc and positioned in the lower portion of said vessel so as to form a lower chamber below said second septum for the combustion of fuel therein and an intermediate chamber between said first and second septa, an elongated conduit extending from the lower portion of said upper chamber through said rst septum and terminating in said intermediate chamber directly above and adjacent said Vent so as to effect the passage of pebbles from the bottom of said intermediate chamber into and through said conduit to said upper chamber upon the passage of an upward blast of gas through said vent into said conduit, means for introducing feed gas into said intermediate chamber, and means for withdrawing an effluent from said intermediate chamber.

11. A method of heating a gas by direct contact with hot pebbles which comprises burning a combustible mixture, passing a blast of the resulting gaseous mixture through an orice into the lower end of a narrow elongated Vertical confined zone directly above said orifice so as to heat and entrain pebbles from the area surrounding said orifice and the lower end of said zone, thereby lifting the resulting hot pebbles through said zone into an upper expanded zone; passing a gas through said upper zone in direct heat exchange with said pebbles; maintaining a compact layer of pebbles in the lower portion of said upper zone while simultaneously passing pebbles by gravity through a plurality of paths distributed over the bottom of said upper zone to a subjacent zone y surrounding said narrow verticalv confined zone, thereby passing freely falling pebbles over substantially the entire horizontal cross section o1 said subjacent zone to a bed of same surrounding end of a narrow elongated vertical confined zone directly above said orifice so as to heat and entrain pebbles from the area surrounding said orifice and the lower end of said zone, thereby lifting the resulting hot pebbles through said zone into an upper expanded heating zone; contacting said hot pebbles in said upper zone with a gas to be heated thereby heating said gas; withdrawing and collecting an eiiiuent from said upper zone; maintaining a compact layer of pebbles in the lower portion of said upper zone while simultaneously passing pebbles by gravity through a pluralityof paths distributed over the bottom of said upper zone to a subjacent zone surrounding said narrow vertical confined zone, thereby passing freely falling pebbles over substantially the entire horizontal cross section of said subjacent zone to a bed of same surrounding said lower end of said narrow zone; and withdrawing gaseous mixture from said subjacent zone.

13. A method of heating gas by direct contact with hot pebbles which comprises burning a combustible mixture; passing a blastl of the resulting gaseous mixture through an orifice into the lower end of a narrow elongated vertical conned zone spaced apart vertically from said orifice and extending to an expanded upper zone, thereby entraining pebbles from the area surrounding said orifice and the lower end of said zone and simultaneously heating and lifting the resulting hot pebbles through said zone into said upper expanded zone; withdrawing gaseous mixture from said upper zone; maintaining a compact layer of pebbles in the lower portion of said upper zone while simultaneously passing pebbles from said layer by gravity through a plurality of paths distributed over the bottom of said upper zone to a subjacent zone surrounding said narrow vertical confined zone, thereby passing freely falling pebbles over substantially the entire horizontal cross section of said subjacent zone to a bed of same surrounding said lower end of said narrow zone; introducing feed gas to said subjacent zone in direct heat exchange with said freely falling pebbles and withdrawing and collecting an eiuent from said subjacent zone.

14. A method for conversion of hydrocarbons which comprises passing a blast of hot combustion gas through an orifice into the lower end of a narrow vertical elongated Aconfined zone directly over said orifice so as to heat and entrain pebbles from the area surrounding said orice and the lower end of said zone, thereby ejecting the resulting hot pebbles through said zone into an upper expanded conversion zone while retaining said combustion gas in a subjacent zone surrounding said narrow zone; contacting the hot pebbles in said conversion zone with hydrocarbon gas so as to heat and convert the same to desirable product; withdrawing and recovering an eiuent from said conversion zone; maintaining a compact layer of pebbles in the bottom of said conversion zone while simultaneously passing pebbles to said subjacent zone by gravity through a plurality of paths distributed over the bottom of said conversion zone, thereby passing freely falling ypebbles through said subjacent zone in direct heat exchange with said combustion gas to a bed of same surrounding said lower end of said narrow zone for reheating and recirculating to the conversion zone; and withdrawing combustion gas from said subjacent zone.

15. A method for conversion of hydrocarbons 'which comprises passing a blast of gas comprising hydrocarbon through an orifice into the lower end of a narrow vertical elongated confined zone spaced apart vertically from said orifice so as to `entrain pebbles from the area surrounding said orifice and the lower end of said zone, thereby ejecting the pebbles through said zone into an upper expanded pebble heating zone while retain ing said hydrocarbon gas in a subjacent conversion zone surrounding said narrow zone; contacting the pebbles in said pebble heating zone with i hot combustion gas so as to heat said pebbles-- to a temperature above a predetermined conversion temperature; withdrawing combustion gas .from said pebble heating zone; maintaining a heating zone to said subjacent conversion zone;

gravitating said pebbles through said subjacent conversion zone in contact with the hydrocarbon y gas therein, thereby heating and converting said hydrocarbon and simultaneously returning said pebbles to a bed of same surrounding said lower end of said narrow zone for recirculating to the pebble heating zone; and withdrawing and col-- lecting an eiuent from said subjacent conversionA zone.

16, A method for conversion of hydrocarbons which comprises passing a blast of hot combustion gas through an orifice into the lower end of a narrow elongated conned zone directly over i said orifice so as to heat and entrain pebbles from the area surrounding said orifice and the lower end of said zone, thereby ejecting the resulting hot pebbles through said zone into an upper expanded separation zone; withdrawing combustion gas from said upper zone; collecting hot pebbles in the bottom of said upper zone and passing the same by gravity through a plurality of paths distributed over the bottom of said upper zone to a subjacent conversion zone surrounding said narrow vertical zone, thereby passing freely falling pebbles through said conversion zone to a bed of same surrounding said lower end of said narrow zone for reheating and recrculating to said upper separation zone; introducing hydrocarbonv gas into said conversion zone into Contact with the gravitating hot pebbles therein so as to effect conversion thereof; and withdrawing a conversion eiiluent from said conversion zone.

17. Apparatus for the treatment of a gas in the presence of pebbles which comprises in combination an upright, elongated, cylindrical vessel having a gas outlet in the top section and an orifice in the bottom thereof; a perforate septum having a central vent of larger size than the other perforations in said septum, said septum being positioned across the upper portion of said vessel so as to form an upper and a lower chamber therein and being adapted for gradually passing pebbles downwardly therethrough uniformly over the horizontal cross section of said vessel except at said vent; a plurality of conduits opening into said lower chamber through the cylindrical walls of said vessel for introducing to and withdrawing gas from said lower chamber; and an elongated open ended conduit of relatively small crosssectional area extending between said vent and said ori'lce in. close spaced-apart relation at its lower end to saidk oriiice so as to provide a passageway for said pebbles to flow into the end of said conduit from the surrounding space and adapted so as to effect the passage of pebbles from the bottom of said lower chamber into and through said conduit into said upper chamber upon the passage of an. upward blast of gas through said oriiice.

18.. Apparatus for the treatment of uid in the presence of heat-exchange pebbles which comprises in. combination an upright elongated cylindrical vessel having a gas outlet in the upper portion and gas inlet oriiice in the bottom thereof, said bottom being cupped to cause flow of said pebbles toward said oriiice; a transverse perforate septum in said vessel intermediate the ends thereof dividing said vessel into an upper cham- `ber and a lower chamber extending from said septum to the lower end of said vessel, the perforations in said septum providing pebble passageways from said upper to said lower chamber; a vent in said septum larger than said perforations providing a passageway for pebbles upwardly therethrough; a gas inlet in said upper chamber; a gas outlet in said lower chamber; and an elongated conduit of relatively small crosssection open at both ends and fixed in said lower chamber in alignment with said oriiice and said vent, its lower end approaching the upper end of said orifice in spaced-apart relation thereto so that a blast of gas injected upwardly through said orice entrains and lifts pebbles from the lower end-of said lower chamber to said upper chamber.

19. Apparatus for the treatment of a Iiuid in contact with pebbles, which comprises in combination an upright, elongated cylindrical vessel having a gas outlet at the vtop and an oriiice in 16y the bottom thereof; a perforated septum having a central vent larger than the other perforations in said septum for the passage of pebbles upwardly therethrough, said septum being positioned across the upward portion of said vessel and forming an upper and lower chamber therein and being adapted for gradually passing pebbles downwardly therethrough uniformly over the horizontal cross-section of said vessel except at said vent while maintaining multiple layers of pebbles thereon; means for introducing gas into said upper chamber; means for removing gas from said lower chamber; and an elongated openended conduit of relatively small cross-sectional area positioned in. said lower chamber in alignment with said vent and said oriiice extending therebetween in close spaced-apart relation at its lower end to said orice so as to provide a passageway for said pebbles to flow into the end of said conduit from the surrounding space, and adapted so as to effect the passage of pebbles from the bottom of said lower chamber into and through said conduit into said upper chamber upon the passage of an upward blast of gas through said oriiice.

CRUZAN ALEXANDER.

HARRIS A. DUTCHER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,405,395 Bahlke et al Aug. 6, 1946 2,412,152 Huff Dec. 3, 1946 2,425,098 Kassel Aug. 5, 1947 2,457,232 Hengstebeck Dec. 28, 1948

Claims

11. A METHOD OF HEATING A GAS BY DIRECT CONTACT WITH HOT PEBBLES WHICH COMPRISES BURNING A COMBUSTIBLE MIXTURE, PASSING A BLAST OF THE RESULTING GASEOUS MIXTURE THROUGH AN ORIFICE INTO THE LOWER END OF A NARROW ELONGATED VERTICAL CONFINED ZONE DIRECTLY ABOVE SAID ORIFICE SO AS TO HEAT AND ENTRAIN PEBBLES FROM THE AREA SURROUNDING SAID ORIFICE AND THE LOWER END OF SAID ZONE, THEREBY LIFTING THE RESULTING HOT PEBBLES THROUGH SAID ZONE INTO AN UPPER EXPANDED ZONE; PASSING A GAS THROUGH SAID UPPER ZONE IN DIRECT HEAT EXCHANGE WITH SAID PEBBLES; MAINTAINING A COMPACT LAYER OF PEBBLES IN THE LOWER PORTION OF SAID UPPER ZONE WHILE SIMULTANEOUSLY PASSING PEBBLES BY GRAVITY THROUGH A PLURALITY OF PATHS DISTRIBUTED OVER THE BOTTOM OF SAID UPPER ZONE TO A SUBJACENT ZONE SURROUNDING SAID NARROW VETICAL CONFINED ZONE, THEREBY PASSING FREELY FALLING PEBBLES OVER SUBSTANTIALLY THE ENTIRE HORIZONTAL CROSS SECTION OF SAID SUBJACENT ZONE TO A BED OF SAME SURROUNDING SAID LOWER END OF SAID NARROW ZONE; AND PASSING A GAS THROUGH SAID SUBJACENT ZONE IN DIRECT HEAT EXCHANGE WITH SAID FREELY FALLING PEBBLES.