US 3871838 A
Improved apparatus for mixing an oxygen containing gas with a vaporized, gasified or atomized hydrocarbon within the mixing chamber of a gas reforming device in which one or more tubes having discharge openings distributed over the flow cross section of the mixing zone supply the oxygen containing gas and further have attached thereto guide baffles which gradually enlarge the unobstructed flow cross section constricted by the tube or tubes.
Description (OCR text may contain errors)
United States Patent Henkel et a1.
1451 Mar. 18, 1975 APPARATUS FOR REACTING VAPORIZED, GASIFIED OR ATOMIZED HYDROCARBON WITH A GAS SERVING AS AN OXYGEN CARRIER Inventors: Hans-Joachim Henkel; Eugen Szabo De Bucs, both of Erlangen; Christian Koch, Nurnberg-Grossgrundlach, all of Germany Assignee: Siemens Aktiengesellschaft, Munich,
Germany Filed: June 21, 1973 App]. No.: 372,311
Foreign Application Priority Data 1 July 3, 1972 Germany 2223656 US. Cl. 48/107, 23/288 R, 48/180 C,
48/180 B, 48/212, 123/3, 261/114 Int. Cl Cl0g 9/04 Field of Search 48/107, 196 R, 93, 102 A, 48/180 R, 212,197 R, 180 C, 180 B, 180 H; 23/288 R, 288 F; 123/119 A, 3,119 E; 261/114 R, 109; 259/4; 239/432 [5 6] References Cited UNITED STATES PATENTS 1,722,339 7/1929 Pauling; 23/288 2,181,153 11/1939 Prickett 2,234,169 3/1941 Houdry et 211 2,291,879 8/1942 Chandler et al. 123/119 2,368,430 1/1945 Smith 2,508,120 5/1950 Longren 2,632,296 31-1953 Houdry 60/39 0 3,441,381 4/1969 Keith et a1. 23/288 Primary Examiner-S. Leon Bashore Assistant Examiner-Peter F. Kratz Attorney, Agent, or Firml(enyon & Kenyon Reilly Carr & Chapin  ABSTRACT Improved apparatus for mixing an oxygen containing gas with a vaporized, gasified or atomized hydrocarbon within the mixing chamber of a gas reforming device in which one or more tubes having discharge openings distributed over the flow cross section of the mixing zone supply the oxygen containing gas and further have attached thereto guide baffles which gradually enlarge the unobstructed flow cross section constricted by the tube or tubes.
10 Claims, 4 Drawing Figures APPARATUS FOR REACTING VAPORIZED, GASIFIED OR ATOMIZED HYDROCARBON WITH A GAS SERVING AS AN OXYGEN CARRIER BACKGROUND OF THE INVENTION This invention relates to apparatus for reforming vaporized gasified or atomized hydrocarbons which are mixed with a gas serving as an oxygen carrier in a reforming device of the type having a mixing zone and an adjoining reaction zone in general, and more particularly to an improved means of supplying the gas serving as the oxygen carrier to the mixing zone.
Reforming devices of this type are used in particular for supplying fuel to internal combustion engines. Through their use, the fuel after being burned will emit a low level of pollutants. Apparatus of this nature are disclosed in US. Pat. applications Ser. No. 218,696 now U.S. Pat. No. 3,828,736, filed on Jan. 18, 1972 and Ser. No. 270,923 now abandoned, filed on July 12, 1972, and are designated therein as gas reformers. For the purpose of this specification, a gas reformer is de fined as apparatus for generating a gaseous fuel by the chemical conversion ofliquid fuel. A liquid fuel such as gasoline and containing hydrocarbons is vaporized, gasified or atomized, mixed with an oxygen carrier gas and then conducted to a reaction zone for conversion into a gas mixture containing carbon monoxide, carbon dioxide and methane, and/or hydrogen which mixture is designated the reformed gas. The oxygen carrier gas is required for a soot free conversion. Generally, this gas will be be comprised partially of exhaust gases fed back from the internal combustion engine and/or other gases which serve as oxygen carriers such as air. The mixture of the oxygen carrying gas and the vaporized hydrocarbon fuel is provided to a catalytic converter at a temperature which lies within the range of the starting temperature of the catalyst used and its temperature load limit. Within the catalytic converter the mixture is passed through a catalyst carrier containing the catalyst used in the conversion. After conversion into the reformed gas, additional gas serving as an oxygen carrier, such as air, is mixed to the reformed gas prior to it being fed to the combustion chambers of the internal combustion engine.
Thus, gas reformers of this nature in general will have a mixing zone which is joined to a reaction zone. The vaporized, gasified, or atomized hydrocarbon fuel (hereinafter wherein one of the words vaporized, atomized, or gasified is used it shall be taken to mean any of the three similar states in which liquid fuel is placed in a state where it can be treated as a gas) is mixed in the mixing zone with an oxygen carrier. The mixture obtained therein is then fed into a reaction zone in which the conversion to a reformed gas takes place. In general the reaction zone will be a catalytic chamber and will preferably include catalyst carriers formed of highly porous sintered bodies having a large number of passage canals for the gas, the passage canals being arranged approximately parallel to each other. Through the use of carriers of this nature, the gas reformers can be minaturized to the extent that they are suitable for use in motor vehicles. As noted above, the use of these gas reformers permits an operation of the internal combustion engine which results in low levels of harmful emissions and thus helps to meet the current environmental standards. In addition, because the starting fuel can be gasoline, such as that currently available at most filling stations, this reduction in harmful emissions is obtained without a change in existing fuel supply facilities.
A number of problems occur in gas reformers such as those described above. These come about because in some cases the mixing of the starting components is not sufficient to achieve generation of the reformed gas. In addition, there is a danger that the flame can backfire from the reaction zone into the mixing zone. Thus, there is a need for a type of gas reformer which assures good mixing and avoids the dangers of backfiring.
SUMMARY OF THE lNVENTlON The present invention solves these problems by providingimproved apparatus for the mixing of the vaporized, gasified or atomized hydrocarbon fuel with the gas serving as an oxygen carrier in gas reformers such as those described above. In particular, uniform mixing of the two starting components is achieved near the reaction zone and thus the possibility of backfiring is eliminated.
To obtain these results, the present invention provides within the mixing zone one or more tubes having discharge openings which are distributed over the cross section of the flow through the mixing zone. This distributes the oxygen carrier gas over the full flow cross section of the hydrocarbon gas. In addition, adjoining the discharge openings guide baffles are provided which extend from the one or several tubes in the direction of the reaction zone gradually enlarging the unobstructed flow cross section as the mixture moves from the one or more tubes into the reaction zone. This results in a close and uniform mixing of the two starting componentsand additionally achieves a laminar flow which has very little turbulence, thereby substantially eliminating the possibility and danger of backfiring of the combustionable gas mixture from the reaction zone into the mixing zone. i
The apparatus of the present invention allows a controllable distribution of the oxygen carrier gas. It is possible, for example, to provide for more air or exhaust gas [oxygen carrier gas] to be mixed with the vaporized fuel at the periphery of the mixing zone than at its center. This can be accomplished through the manner in which the discharge openings of the tube or tubes are arranged. Similarly, if desired, the oxygen carrier can be mixed uniformly over the entire cross-sectional area of the mixing zone. In that case, the discharge openings would be distributed uniformly across the crosssectional area of the mixing zone. The tubes referred to herein can be not only a conventional structure such as a pipe line but can also be systems of tubes which are formed, for example, in a ceramic body.
It is also possible to arrange the tubes within the mixing chamber so that they are capable of feeding different gases as oxygen carriers. For example, the tubes at the outer periphery of the mixing zone may be connected with a chamber for air and the tubes closer to the center with a chamber for exhaust gases from the internal combustion engine. With this arrangement, air will be mixed with the fuel at the discharge openings at the periphery of the mixing zone and exhaust gases mixed at the center of the mixing zone.
In some cases, it may be desirable to feed the gas to the tube or tubes at right angles to the flow direction of the gas mixture of the fuel and oxygen carrier. The
tubes can be arranged in an arrangement where they are parallel to each other and can also be arranged in the form of concentric rings with at least one radially extending connection. The concentric rings need not necessarily be circular but may also be squares or rectangles which have rounded corners. In an additional embodiment, a single tube, or a plurality of tubes in the form of spirals can be used to supply the oxygen carrier gas to the mixing zone.
In the illustrated embodiment, the guide baffles extending from the tubes are formed as part of the wall of the tube thereby resulting in a simplified mechanical design of the apparatus of the present invention. The guide baffles will preferably be plane surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic-cross-sectional view ofa gas reformer according to the present invention.
FIG. 2 is a cross section through the tubes of the gas reformer of FIG. 1.
FIGS. 3 and 4 are similar cross sections illustrating alternate arrangements for the tubes of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a gas reformer containing the improved mixing apparatus of the present invention and is schematically shown in cross section. The reformer elements are contained within a common housing having a portion 11 designated as a mixing zone and a portion 12 designated as a reaction zone. Hydrocarbon fuel is introduced into the mixing zone 11 through an injection jet 13. Within the mixing zone are provided a plurality of tubes 14 which serve to provide an oxygen carrier gas to the fuel injected into the mixing zone. The oxygen carrier gas is provided through an inlet 15 to a chamber 16 which is mounted laterally at the mixing zone 11 and is in communication with tubes 14. This permits the gas to be fed to the reactor at right angles to the flow direction of the gas mixture. Tubes 14 contain a plurality of openings 17 which distribute the oxygen carrier gas over the entire flow cross section of the gas mixture. For ignition of the gas mixture a spark or glow plug 18 is provided in the mixing zone. Adjoining the tubes 14 are guide baffles 19 formed as part of the walls of the tubes 14. These are designed as plane surfaces and gradually enlarge the unobstructed flow section in the direction of the reaction zone 12.
After mixing in the mixing chamber 11, the gas mixture enters the reaction zone 12 wherein it is converted to the reformed gas. The reformed gas then leaves the reactor through the pipe line 20 and, after an addition of a further amount of oxygen carrying gas, is provided, for example, to the combustion chambers of an internal combustion engine in a motor vehicle.
An additional opening 21 through which air may be provided during start up is installed. On start up, gasoline or another hydrocarbon fuel is introduced into the mixing zone 11 through the injection jet 13 at the same time as air is provided through the opening 21. The mixture formed by the vaporized gasoline and the air is then ignited by the glow plug 18, after which the glow plug is disconnected. Air is supplied into the mixing zone through the opening 21 until the starting temperature of the catalyst in the reaction zone 12 is reached. At this point, the air supplied through opening 21 is cut off and the oxygen carrying gas, i.e., air and/or exhaust gas, is then fed into the mixing zone through the tubes 14. In addition, by relocating the ignition device 18, just before the reaction zone 12, air during start up may be provided through the tubes 14 and the opening 21 eliminated.
In the reaction zone, there are provided, for example, three catalyst carriers 22 each in the form of porous sintered blocks. The sintered blocks 22 are preferably provided with a large number of passage canals 23 which are arranged approximately parallel to each other in the direction of gas flow. Typically, the sintered blocks 22 will have a cross sectional area of about mm by 80 mm and a thickness of about 15 mm. They are normally arranged within the reaction zone at a mutual spacing of about 5mm. As an example of the type of sintered blocks which may be used are blocks made of a highly porous material, for example, of aluminum oxide and/or magnesium oxide or magnesiumlaluminum silicate. Blocks of this nature should have a pore volume which is between 20 and 60 percent, preferably between 40 and 50 percent. The parallel passage canals which are perpendicular to the major surface of the singered block will have a diameter for example, of- O.l to 2 mm. From the passage canals the gas mixture will get into the catalytically active centers in the free pores of the sinter block to cause the required reaction to take place. The number of passage canals per square centimeter depends on the diameter of the passage canals. For example, with passages having a diameter of about 1 mm, 1 square centimeter of the sintered block will have about 40 passages.
Preferred catalysts for the conversion of fuel are nickel catalyst, a platinum catalyst or a nickel-platinum mixed catalyst. In general any catalyst which will convert the fuel into a reformed gas containing carbon monoxide, carbon dioxide, methane, and/or hydrogen may be used. Nickel sponge, for example, can be used. This comprises nickel with a large active surface which does not sinter together at the temperature prevailing at the catalyst. By providing it with a gas which has carbon monoxide and methane and/or hydrogen in it, the internal combustion engine will be fed with a fuel which has a high octane number of over and which will probably be in the range of 110. This permits the internal combustion engine to be operated using an antiknock fuel without the addition of harmful substances. In addition, the catalyst used for the conversion of fuel which may be nickel or platinum can be doped with uranium which will cause the preservation of the active centers in the catalyst. For a discussion of other suitable catalysts which may be used see US. applications Ser. No. 334,932, filed on Feb. 22, 1973 and Ser. No. 336,062, filed on Feb. 26, 1973.
FIG. 2 shows a cross section II-II through the apparatus of FIG. 1. As shown, the oxygen carrier gas will enter through the inlet pipe 15 into the chamber 16 from which it is distributed to the pipes 14 and exists from the passage openings 17 to mix with the fuel.
FIG. 3 shows a cross sectional view of a different embodiment wherein the tubes 14 of FIG. 1 are of circular cross section. As shown, tubes 30, 31 and 32 are arranged in concentric rings and provided with radial connecting lines 33 and 34. The use of the two feeding lines 33 and 34 permits feeding different gases from the two chambers 35 and 36. For example, air may be provided to the chamber 35 from which it will flow through the tube 33 into the circular tube 30. At the same time, exhaust gases may be provided to the chamber 36 from which they flow through the radial pipe 34 to the two circular tubes 31 and 32. The two oxygen carrying gases, i.e., air and the exhaust gases will then enter into the mixing zone designated 39 via the respective discharge openings 37 and 38 to be mixed with the vaporized fuel.
The embodiment of FIG. 4 illustrates a spiral tube. Here a single tube 40 is arranged in the form of a spiral having discharge openings 42. Thus, again the oxygen carrier gas is effectively distributed over the cross sectional area of the mixing zone 41.
Although particularly useful in motor vehicle internal combustion engines, the apparatus of the present invention may also be used for feeding industrial and residential burners. In addition, the combustible gases produced in the reactor of the present invention may also be used, for example, as a reducing gas in metallurgical processes, particularly in industrial burners.
Thus an improved apparatus for mixing an oxygen carrier in a gas reformer has been shown. Although specific embodiments have been illustrated and de= scribed it will be obvious to those skilled in the art that various modifications may be made without departing from the spirit of the invention which is intended to be limited solely by the appended claims.
What is claimed is:
1. In apparatus for the catalytic reaction ofa mixture of evaporated liquid fuel and an oxygen carrying gas to form reformed gas, comprising:
a. a mixing chamber which is free of catalytic material;
b. a reaction chamber adjacent to the mixing chamber and connected therewith, which contains catalytic material;
c. means for feeding the evaporated liquid fuel to said mixing chamber in such a manner that a flow through the mixing chamber and the reaction chamber is established; and
(1. means within the mixing chamber to mix the oxygen carrying gas with said evaporated liquid fuel, wherein the improvement comprises improved mixing means comprising:
l. at least one tube with a multiplicity of discharge openings for the oxygen carrying gas, which openings are distributed over the flow cross section' of the mixing chamber in such a manner that the oxygen carrying gas leaves said tube perpendicular to the flow direction of the evaporated liquid fuel flow through the mixing chamber;
2. gas guide surfaces arranged adjacent to the discharge openings at the tube, said surfaces extending in the flow direction of the evaporated liquid fuel flow up to the vicinity of the reaction chamber, said surfaces gradually increasing the clear flow cross section narrowed down by said tube; and
3. means for supplying the oxygen carrying gas to said tube.
2. The invention according to claim I wherein said at least one tube comprises a plurality of tubes parallel to each other.
3. The invention according to claim I wherein said at least one tube comprises a plurality of tubes in the form of concentric rings supplied by at least one radial connection.
4. The invention according to claim 1 wherein said at least one tube comprises a single tube of a spiral shape.
5. The invention according to claim 1 wherein said guide surfaces are formed as part of the tube wall.
6. The invention according to claim 1 wherein said guide surfaces are plane surfaces.
7. The invention according to claim 1 wherein said discharge openings are uniformly distributed over the flow cross section.
8. The invention according to claim 1 wherein a plurality of said tubes are provided, said supply means include at least two chambers to supply at least two oxygen carrying gases, and different ones of said tubes are connected to different ones of said at least two chamnals formed therein.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,871,838
D E I March 18, 1975 INVENTOR(S) Hans-Joachim Henkel et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
In the Foreign Application Priority Data change the file number of the German application upon which the claim for priority is based from "22 236 56" to-P 22 326 56.3--
Signed and sealed this 6th day of May 1975.
C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks