Abstract:
A hydrocarbon fuel reforming method is disclosed suitable for producing synthesis hydrogen gas from reactions with hydrocarbons fuels, oxygen, and steam. A first mixture of an oxygen-containing gas and a first fuel is directed into a first tube  108  to produce a first reaction reformate. A second mixture of steam and a second fuel is directed into a second tube  116  annularly disposed about the first tube  108  to produce a second reaction reformate. The first and second reaction reformates are then directed into a reforming zone  144  and subject to a catalytic reforming reaction. In another aspect of the method, a first fuel is combusted with an oxygen-containing gas in a first zone  108  to produce a reformate stream, while a second fuel under steam reforming in a second zone  116 . Heat energy from the first zone  108  is transferred to the second zone  116.

Description:
RELATED U.S. APPLICATION DATA 
     This Application is a divisional of application Ser. No. 08/703,398, filed Aug. 26, 1996 now U.S. Pat. No. 6,126,908, upon which a claim of priority is based. 
    
    
     GOVERNMENT RIGHTS 
     The Government has rights in this invention pursuant to Contract No. DE-AC02-92CE50343, awarded by the U.S. Department of Energy. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the development of synthesis gas for use in power generation and, in particular, to the processing of hydrocarbon fuel to produce hydrogen gas. 
     BACKGROUND OF THE INVENTION 
     Fuel cells continue to play an increasingly important role in power generation for both stationary and transportation applications. A primary advantage of fuel cells is their highly efficient operation which, unlike today&#39;s heat engines, are not limited by Carnot cycle efficiency. Furthermore, fuel cells far surpass any known energy conversion device in their purity of operation. Fuel cells are chemical power sources in which electrical power is generated in a chemical reaction between a reducer (hydrogen) and an oxidizer (oxygen) which are fed to the cells at a rate proportional to the power load. Therefore, fuel cells need both oxygen and a source of hydrogen to function. 
     There are two issues which are contributing to the limited use of hydrogen gas today. Firstly, hydrogen gas (H 2 ) has a low volumetric energy density compared to conventional hydrocarbons, meaning that an equivalent amount of energy stored as hydrogen will take up more volume than the same amount of energy stored as a conventional hydrocarbon. Secondly, there is presently no widespread hydrogen infrastructure which could support a large number of fuel cell power systems. 
     An attractive source of hydrogen to power fuel cells is contained in the molecular structure of various hydrocarbon and alcohol fuels. A reformer is a device that breaks down the molecules of a primary fuel to produce a hydrogen-rich gas stream capable of powering a fuel cell. Although the process for reforming hydrocarbon and alcohol fuels is established on a large industrial basis, no known analogous development has occurred for small-scale, highly integrated units. 
     Therefore, a need exists for a more compact apparatus for generating hydrogen gas from a variety of hydrocarbon fuel sources for use in a fuel cell to power a vehicle. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a reformer and method for converting an alcohol or hydrocarbon fuel into hydrogen gas and carbon dioxide. 
     The reformer includes a first vessel having a partial oxidation reaction zone and a separate steam reforming reaction zone that is distinct from the partial oxidation reaction zone. The first vessel has a first vessel inlet at the partial oxidation reaction zone and a first vessel outlet at the steam reforming zone. The reformer also includes a helical tube extending about the first vessel. The helical tube has a first end connected to an oxygen-containing source and a second end connected to the first vessel at the partial oxidation reaction zone. Oxygen gas from an oxygen-containing source can be directed through the helical tube to the first vessel. A second vessel having a second vessel inlet and second vessel outlet is annularly disposed about the first vessel. The helical tube is disposed between the first vessel and the second vessel and gases from the first vessel can be directed through the second vessel. 
     The method includes directing oxygen-containing gas through a helical tube which is disposed around a first vessel. Hydrocarbon vapor and steam are directed into the helical tube to form a mixture of oxygen gas, fuel vapor and steam. The mixture of oxygen gas, fuel vapor and steam are directed into the first vessel. The fuel vapor partially oxidizes to form a heated reformate stream that includes carbon monoxide and hydrogen gas. The remaining fuel vapor is steam reformed in the heated reformate stream to form hydrogen gas and carbon monoxide. The heated reformate stream is directed over the exterior of the helical tube, whereby the heated reformate stream heats the mixture in the helical tube. A portion of the carbon monoxide gas of the reformate stream is converted to carbon dioxide and hydrogen gas by a high temperature shift reaction. At least a portion of the remaining carbon monoxide gas of the reformate stream is converted to carbon dioxide and hydrogen gas by a low temperature shift reaction. 
     In another embodiment of a reformer for converting a hydrocarbon fuel into hydrogen gas and carbon dioxide, the apparatus includes a first tube which has a first tube inlet for receiving a first mixture of an oxygen-containing gas and a first fuel, which can be a hydrocarbon or an alcohol, and a first tube outlet for conducting a first reaction reformate of the first mixture. A second tube is annularly disposed about the first tube, wherein the second tube has a second tube inlet for receiving a second mixture of a second fuel, which can be a hydrocarbon or an alcohol, and steam. The second tube has a second tube outlet for conducting a second reaction reformate of the second mixture. A catalyst reforming zone is annularly disposed about the second tube. The first reaction reformate and the second reaction reformate can be directed through the first tube outlet and the second tube outlet, respectively, to the catalyst reforming zone for further reforming of the mixtures. In a preferred embodiment, a hydrocarbon fuel fractionator is attached at the first tube inlet and second tube inlet. The fractionator can separate a heavy portion from the hydrocarbon fuel for subsequent direction to a partial oxidation zone in the first tube. A light portion can be separated from the hydrocarbon fuel for subsequent direction to a steam reforming zone in the second tube. 
     In another embodiment of the method for converting a hydrocarbon or alcohol fuel into hydrogen gas and carbon dioxide, a first mixture of first hydrocarbon or alcohol fuel and oxygen-containing gas is directed into a first tube. The hydrocarbon or alcohol fuel in the first mixture spontaneously partially oxidizes to form a first heated reformate stream that includes hydrogen gas and carbon monoxide. A second mixture of a second hydrocarbon or alcohol fuel and steam is directed into a second tube annularly disposed about the first tube. The second hydrocarbon or alcohol fuel of the second mixture partially steam reforms to form a second heated reformate stream that includes hydrogen gas and carbon monoxide. The first heated reformate stream and second heated reformate stream are directed through a catalyst reforming zone to further reform the reformate streams to hydrogen gas and carbon dioxide. In a preferred embodiment, the hydrocarbon fuel prior to direction into the first tube and the second tube is fractionated into heavy portion of the hydrocarbon fuel and a light portion of the hydrocarbon fuel. The heavy portion is subsequently directed to the partial oxidation zone. The light portion is directed to the steam reforming zone. 
     This invention has many advantages. The apparatus can use a variety of hydrocarbon fuels, such as gasoline, JP-8, methanol and ethanol. The partial oxidation reaction zone allows the fuel to partially burn while not forming soot and while providing heat to the steam reforming zone and the other portions of the reactor annularly disposed around the partial oxidation zone. Further, the apparatus is sufficiently compact for use in an automobile. In some embodiments, the apparatus includes a high temperature shift catalyst which allows the apparatus to be more compact and lighter in weight than if only a low temperature shift catalyst is used. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an orthogonal projection side view of one embodiment of the apparatus of the present invention; 
     FIG. 2 is an orthogonal projection side view of a second embodiment of the apparatus of the present invention; and, 
     FIG. 3 is an orthogonal projection side view of a third embodiment of the apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The features and details of the method and apparatus of the invention will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. The same numeral present in different figures represents the same item. It will be understood that the particular embodiments of the invention are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. All percentages and parts are by weight unless otherwise indicated. 
     One embodiment of the invention is shown in FIG. 1. A reformer  10  has a reformer vessel  12 . The reformer vessel  12  can be cylindrical in shape. The reformer  10  has an upper portion  14  and a lower portion  16 . Disposed in the center of the reformer vessel  12  is a first vessel  18  which extends substantially the height of the reformer vessel  12 . The first vessel  18  has a first vessel inlet  20  for receiving gases into the first vessel  18  and can tangentially direct the gases through the first vessel  18 . The first vessel  18  has a first vessel outlet  22  at the upper portion  14  of the reformer  10  for gases to exit the first vessel  18 . A perforated plate  31  is located at the first vessel outlet  22  and covers the diameter of the first vessel  18 . A partial oxidation reaction zone  24  is in the lower portion  16  of the first vessel  18 . 
     The partial oxidation zone  24  is suitable for partial oxidation of a hydrocarbon or alcohol fuel with oxygen to form a mixture including carbon monoxide, steam and hydrogen gas. A steam reforming zone  26  is above the partial oxidation zone  24  and includes a steam reforming catalyst  28 . Preferably, the steam reforming catalyst  28  includes nickel with amounts of a noble metal, such as cobalt, platinum, palladium, rhodium, ruthenium, iridium, and a support such as magnesia, magnesium aluminate, alumina, silica, zirconia, singly or in combination. Alternatively, the steam reforming catalyst  28  can be a single metal, such as nickel, supported on a refractory carrier like magnesia, magnesium aluminate, alumina, silica, or zirconia, singly or in combination, promoted by an alkali metal like potassium. The steam reforming zone  26  can autothermally reform steam and methane generated in the partial oxidation zone  24  to hydrogen gas and carbon monoxide. The steam reforming catalyst  28 , which can be granular, is supported within the partial oxidation zone  24  by a perforated plate  30  and a perforated plate  31 . 
     A helical tube  32  extends about the length of the first vessel  18 . A first end  34  of the helical tube  32  is located at an inlet housing  33 . An oxygen source  42  is connected to the inlet housing  33  by a conduit  35  with a first end inlet  36  for receiving oxygen-containing gas from an oxygen gas zone  40 . A second end  44  of the helical tube  32  is connected at the first vessel inlet  20 . Examples of suitable oxygen-containing gas include oxygen (O 2 ), air, etc. A fuel inlet  46  is joined to the helical tube  32  proximate to the second end  44 . A conduit  50  extends from a fuel source  48  to the fuel inlet  46 . Examples of suitable fuels include hydrocarbons which encompass alcohols, also. Fuels include gasoline, kerosene, JP-8, methane, methanol and ethanol. A steam inlet  52  is proximate to the fuel inlet  46 . Steam can be directed from a steam source  54  to a steam tube  56  through the first steam inlet  52  into the helical tube  32 . In another embodiment, fuel and steam can be directed into the helical tube  32 . 
     A second vessel  58  is annularly disposed about the first vessel  18 . A second vessel inlet  60  receives gaseous products from the first vessel outlet  22 . A second vessel outlet  62  at the lower portion  16  of the reformer  10  allows gas to exit the second vessel  58 . The helical tube  32  is disposed between the first vessel  18  and the second vessel  58  and gases from the first vessel  18  can be directed through the second vessel  58  from the second vessel inlet  60  over and around the helical tube  32  to the second vessel outlet  62 . A flow distribution region  63  conducts gas from the second vessel outlet  62  to a high temperature shift zone  64 . Additional steam or water can be directed from a steam source into the second vessel  58  through a second steam inlet  53  to provide added steam to provide added cooling and further the reformation of the fuels. 
     A high temperature shift zone  64  is annularly located between the second vessel  58  and the reformer vessel  12  and includes a high temperature shift catalyst  66 . An example of a suitable high temperature shift catalyst  66  are those that are operable at a temperature in the range of between about 300° C. and about 600° C. Preferably the high temperature shift catalyst  66  includes transition metal oxides, such as ferric oxide (Fe 2 O 3 ) and chromic oxide (Cr 2 O 3 ). Other types of high temperature shift catalysts include iron oxide and chromium oxide promoted with copper, iron silicide, supported platinum, supported palladium, and other supported platinum group metals, singly and in combination. The high temperature shift catalyst  66  is held in place by a perforated plate  68  and a perforated plate  70 . Gas can pass through the high temperature shift zone  64  through the perforated plate  70  to a sulfur removal zone  71 . 
     Above the high temperature shift zone  64  is the sulfur removal zone  71 . The sulfur removal zone  71  includes a catalyst which can reduce the amount of hydrogen sulfide (H 2 S), which is deleterious to a low temperature shift catalyst, in the gas stream to a concentration of about one part per million or less. An example of a suitable catalyst includes a zinc oxide. The sulfur removal zone  71  is sized depending on the type of fuel used. If a low sulfur fuel is used, a small sulfur removal zone is needed. If a high sulfur fuel is used, a larger sulfur removal zone is necessary. Gas can pass from the sulfur removal zone  71  through a perforated plate  73  to cooling zone  72 . 
     The cooling zone  72  includes a plurality of vertical fins  74  which radiate from the second vessel  58  to the reformer vessel  12 , and extends between high temperature shift zone  64  to low temperature shift zone  76 . 
     A cooling tube  78  is helically disposed about the second vessel  58  and is attached to the vertical fins  74 . The cooling tube  78  has a cooling tube inlet  80  for receiving a cooling medium, such as water, through the cooling tube  78  to a cooling tube outlet  82 . In another embodiment, the cooling tube  78  is wound a second series of times around the second vessel  58 . The gaseous products from the high temperature catalyst zone  64  can pass between the vertical fins  74  and pass over the cooling tube  78  allowing gaseous products to cool. 
     A low temperature shift zone  76  is annularly disposed above the cooling zone  78  and between the second vessel  58  and the reformer vessel  12  and includes a low temperature shift modifying catalyst  84  for reducing carbon monoxide to a level of less than about one percent, by volume, or below. An example of a suitable low temperature modifying catalyst  84  are those that are operable at a temperature in a range of between about 150° C. and about 300° C. Preferably, the low temperature modifying catalyst  84  includes cupric oxide (CuO) and zinc oxide (ZnO). Other types of low temperature shift catalysts include copper supported on other transition metal oxides like zirconia, zinc supported on transition metal oxides or refractory supports like silica or alumina, supported platinum, supported rhenium, supported palladium, supported rhodium and supported gold. The low temperature shift zone catalyst  84  is held in place by a lower perforated plate  86  and an upper perforated plate  88 . Gaseous products from the cooling zone  72  can pass through the perforated plate  86 , through the low temperature shift zone  76 , and through the upper perforated plate  88 . An exit zone  90  is above the low temperature shift zone  76  and has a reformer exit  92 . 
     In the method for converting hydrocarbon fuel into hydrogen gas, an oxygen-containing gas, such as air, is directed from the oxygen source  42  through the conduit  35 , to the inlet housing  33 , to the oxygen gas zone  40 , and into the first end inlet  36  of the helical tube  32 . The reformer  10  can operate at a pressure in the range of between about 0 and 500 psig. The oxygen-containing gas, such as air, is preheated to a temperature of about 450° C. In a preferred embodiment, air has a velocity of greater than about 40 meters per second. 
     A suitable hydrocarbon or alcohol vapor is directed from the fuel source  48  through the fuel tube  50  to the fuel inlet  46 . Examples of suitable hydrocarbon fuels include gasoline, JP-8, methanol, ethanol, kerosene and other suitable hydrocarbons typically used in reformers. Gaseous hydrocarbons, such as methane or propane, can also be used. Steam is directed from the steam source  54  through steam tube  56  to first steam inlet  52 . The steam has a temperature in the range between about 100 and about 150° C. The air, steam and hydrocarbon fuel are fed at rates sufficient to mix within the helical tube  32  and spontaneously partially oxidize as the mixture enters the partial oxidation zone  24  through the first vessel inlet  20  to form a heated reformate stream that includes carbon monoxide and hydrogen gas. In a preferred embodiment, oxygen-containing gas is tangentially directed around the interior of the partial oxidation zone  24 , which is an empty chamber. In the partial oxidation zone  24 , the reformate products can include methane, hydrogen gas, water and carbon monoxide. The partial oxidation zone  24  has a preferred temperature in the range of between about 950° C. and about 1150° C. A heavier fuel is preferentially run at the higher end of the temperature range while a lighter fuel is run at a lower end of the temperature range. 
     From the partial oxidation zone  24 , reformate products are directed through the perforated plate  30  to the steam reforming zone  26 . In the steam reforming zone  26 , the remaining hydrocarbon vapor in the heated reformate stream from the partial oxidation zone  24  is steam reformed in the presence of the steam reforming catalyst  28  into hydrogen gas and carbon monoxide. The steam reforming zone  26  typically has a temperature in the range of between about 700 and 900° C. The partial oxidation reaction provides sufficient heat to provide heat to the helical tube  32  to preheat the air and other contents of the helical tube  32  and also provide heat to the steam reforming step. The hydrocarbon fuel is burned partly in the partial oxidation zone  24  and the remainder of the fuel with the steam is mixed with the partial oxidation zone combustion products for steam reforming and hydrocarbon shifting to carbon monoxide and hydrogen gas in the presence of the steam reforming catalyst  28 . The heated reformate stream exiting from the steam reforming zone  26  has a temperature of between about 700° C. and about 900° C. The heated reformate stream is directed between the first vessel  18  and the second vessel  58  and around the exterior of the helical tube  32 , whereby the heated reformate stream is cooled by heating the contents of the helical tube  32  and also the first vessel  18  and the second vessel  56 . 
     The heated reformate stream exits the second vessel outlet  62  to the flow distribution zone  63 , where it has been cooled to a temperature of between about 300° C. and about 600° C. and is directed through the perforated plate  68  to the high temperature shift zone  64  where essentially all of the carbon monoxide is removed or reduced by contacting the heated reformate stream with the high temperature shift catalyst  66  at a temperature in the range of between about 300° C. and 600° C. The high temperature shift zone  64  operates adiabatically to reduce the carbon monoxide levels with modest temperature rise. In one embodiment, the heated reformate stream entering the high temperature shift zone  64  has about fourteen to seventeen percent carbon monoxide, by volume, and exits the high temperature shift zone  64  with about two to four percent carbon monoxide, by volume. 
     The high temperature shift zone-treated reformate stream is directed through the sulfur removal zone  71  where the hydrogen sulfide content of the stream is reduced to a concentration of less than about one part per million. From the sulfur removal zone  71 , the reformate is directed to the cooling zone  72  where the stream contacts the vertical fins  74  and the cooling tubes  78  to lower the temperature of the stream to between about 150° C. and about 300° C. because the low temperature shift catalyst  84  is temperature sensitive and could possibly sinter at a temperature of above about 300° C. The cooling zone  72  cools the high temperature reformate gas for the low temperature shift zone  76 . The cooling zone tubes  78  operate continuously flooded to allow accurate and maximum steam side heat transfer, to reduce fouling and corrosion to allow use of contaminated water, and to achieve a constant wall minimum temperature. 
     The reformate stream is directed through the perforated plate  86  to the low temperature shift reaction zone  76  where the reformate stream contacts the low temperature shift catalyst  84 , converting at least a portion of the remaining carbon monoxide gas of the reformate stream to carbon dioxide by the low temperature shift reaction to form a product stream. The low temperature shift reaction zone  76  operates adiabatically to reduce the remainder of the carbon monoxide to trace levels with modest catalyst temperature rise. The resulting gas product stream exits the low temperature shift reaction zone  76  through the perforated plate  88 , and to the exit gas zone  90  and reformer exit  92 . The exiting product stream can have a composition of about 40% hydrogen gas and less than one percent carbon monoxide on a wet volume basis. 
     A second embodiment of the invention is shown in FIG. 2. A second reformer  100  has a reformer shell  102 . The reformer shell  102  has an upper portion  104  and a lower portion  106 . Disposed in a center of the reformer shell  102  is a first tube  108  which extends substantially the height of the reformer shell  102 . The first tube  108  has a first tube inlet  110  at the lower portion  106  for receiving gases into the first tube  108 . The first tube  108  is configured for receiving a first mixture of oxygen and first hydrocarbon fuel. A first tube outlet  112  is configured for directing a first reaction reformate of the first mixture to a mixing zone  114 . 
     A second tube  116  is annularly disposed about the first tube  108 . The second tube  116  has a second tube inlet  118  for receiving second hydrocarbon fuel and steam. The second tube  116  also has a second tube outlet  120  for directing a second reaction reformats of a second mixture. The second tube  116  can include a steam reforming catalyst. An example of a suitable catalyst includes nickel with amounts of a noble metal such as cobalt, platinum, palladium, rhodium, ruthenium, iridium, and a support such as magnesia, magnesium aluminate, alumina, silica, zirconia, singly or in combination. Alternatively, the steam reforming catalyst can be a single metal, such as nickel, supported on a refractory carrier like magnesia, magnesium aluminate, alumina, silica, or zirconia, singly or in combination, promoted by an alkali metal like potassium. In another embodiment, the second tube  116  can be annularly disposed within the first tube  108 , wherein steam and fuel can be directed into the center tube and fuel and oxygen can be directed into the tube annularly disposed around the center tube. 
     An oxygen source  122  is connected by an oxygen tube  124  to the first tube  108 . An example of a suitable oxygen source  122  is oxygen gas or air. A steam source  126  is connected to the second tube  116  by a steam tube  128 . In one embodiment, the steam source  126  can provide a source of steam at a temperature of about 150° C. and a pressure of about 60 psia. 
     A fuel source  130  is connected by a fuel tube  132  to a fractionator  134  The fuel source  130  includes a suitable fuel, such as a hydrocarbon, including gasoline, JP-8, kerosene, also alcohol including methanol and ethanol. The fractionator  134  has a light portion outlet  136  for directing a light portion from the fractionator  134 , and a heavy portion outlet  138  for directing a heavy portion from the fractionator  134 . The heavy portion can be directed from the heavy portion outlet  138  through a heavy portion tube  140  to the first tube inlet  110 . The light portion can be directed from the light portion outlet  138  through a light portion tube  142  to the second tube inlet  118 . In another embodiment, separate sources can be used for the heavy portion (first hydrocarbon fuel) and the light portion (second hydrocarbon fuel) without having a fractionator. 
     A catalyst reforming zone  144  is annularly disposed about the second tube  116 . A first reaction reformate and second reaction reformate can be directed through the first tube outlet  112  and the second tube outlet  120 , respectively, to the mixing zone  114  above the catalyst reforming zone  144 . 
     The catalyst reforming zone  144  includes a catalyst  147  for further reforming of the mixtures to hydrogen gas. An example of a suitable catalyst  147  includes nickel with amounts of a noble metal such as cobalt, platinum, palladium, rhodium, ruthenium, iridium, and a support such as magnesia, magnesium aluminate, alumina, silica, zirconia, singly or in combination. Alternatively, the catalyst  147  can be a single metal, such as nickel, supported on a refractory carrier like magnesia, magnesium aluminate, alumina, silica, or zirconia, singly or in combination, promoted by an alkali metal, like potassium. The catalyst reforming zone  144  can have a height that is substantially the length of the first tube  108  and the second tube  116 . The catalyst reforming zone  144  is sufficiently porous to allow passage of gas from an exit zone  146 . The catalyst  147  in the catalyst reforming zone  144  is held in place by a lower perforated plate  148  and an upper perforated plate  150 . Product gases of the catalyst reforming zone  144  can exit the second reformer  100  from the exit zone  146  through the reformer shell exit  152 . 
     In the second embodiment of the invention for converting hydrocarbon fuel into hydrogen gas and carbon dioxide, a fuel is directed from fuel source  130  to the fractionator  134  through the fuel tube  132 . The fuel is separated into a light portion and a heavy portion in the fractionator  134 . The heavy portion is directed from the heavy portion outlet  138  through the heavy portion tube  140  to the first tube inlet  110 . An oxygen-containing gas, such as air, is directed from the oxygen source  122  through the oxygen tube  124  to the first tube inlet  110 . The oxygen-containing gas and the heavy portion of the hydrocarbon fuel form a mixture in the first tube  108 , whereby the hydrocarbon fuel of the first mixture spontaneously partially oxidizes to form a first heated reformate stream that includes hydrogen gas and carbon monoxide. The first heated reformate stream can be heated to about 1,525° C. The ratio of fuel to oxygen is adjusted depending upon the type of fuel used. A heavier fuel can require a higher combustion temperature. The partial oxidation of the fuel results in the fuel mixture that includes carbon monoxide, water, hydrogen gas and methane. Excess heat from the partial oxidation reaction allows transfer of heat from the first tube  108  to the second tube  116 . By burning the heavy portion at a temperature of above about 1,375° C., there is no significant formation of carbon soot or tar in the partial oxidation zone of, for example, the first tube  108 . If necessary, ignition can be with a hot surface igniter or a spark plug. 
     The light portion of the fuel is directed from the light portion outlet  136  of the fractionator  134  through the light portion tube  142  to the second tube  116 . Steam is directed from the steam source  126  through the steam tube  128  to the second tube inlet  118  into the second tube  116 . Also, oxygen gas is directed from the oxygen source  122  through the oxygen tube  124  to the second tube inlet  118  into the second tube  116 . In another embodiment, only steam is directed with a light portion of hydrocarbon fuel into second tube  116 . A second mixture of oxygen-containing gas, a light portion of hydrocarbon fuel and steam is formed in the second tube  116  annularly disposed about the first tube  108 . The hydrocarbon fuel of the second mixture partially reacts to form a second heated reformate stream that includes hydrogen gas and carbon monoxide. In the presence of steam, the second mixture partially steam reforms. The heat from the reaction in the first tube  108  provides energy to help cause the reaction to progress in the second tube  116 . 
     The first heated reformate stream from the first tube  108  and the second heated reformate stream from the second tube  116  are directed through the first tube outlet  112  and the second tube outlet  120 , respectively, into the mixing zone  114 . The separate tubes  108 , 116  allow carbon reduced operation at high fuel to oxygen ratios of about four to one. It also allows using distillate fuels, such as gasoline, diesel fuel, jet fuel or kerosene, whereby heavy portion type fuels are preferentially directed to the first tube  108  for high-temperature combustion necessary to break heavy molecules while the light portion-type vapors are directed to the second tube  116  for partial steam reforming as a result of thermal contact with the combustion chamber. The first heated reformate stream and the second heated reformate stream mix within the mixing zone  114 . The mixture is directed from the mixing zone  114  through the catalyst reforming zone  144  to the exit zone  146 . In the catalyst reforming zone  144 , the remainder of the carbon monoxide is reformed to carbon dioxide to form product stream. The product stream exits through the exit zone  146  and from the second reformer  100  through the reformer shell exit  152 . 
     Another embodiment of the invention is shown in FIG. 3. A third reformer  200  has a reformer shell  202 . The reformer shell  202  has an upper portion  204  and a lower portion  206 . Disposed in a center of the reformer shell  202  is a first tube  208 . The first tube  208  has a first tube inlet  210  at the lower portion  206  for receiving gases into the first tube  208 . The first tube  208  has a first tube outlet  212  at the upper portion  204  for gases to exit the first tube  208 . The first tube  208  includes a steam reforming catalyst  214  for reforming a hydrocarbon in the presence of steam. An example of a suitable steam reforming catalyst  214  is nickel with amounts of a noble metal such as cobalt, platinum, palladium, rhodium, ruthenium, iridium, and a support such as magnesia, magnesium aluminate, alumina, silica, zirconia, singly or in combination. Alternatively, the steam reforming catalyst  214  can be a single metal, such as nickel, supported on a refractory carrier like magnesia, magnesium aluminate, alumina, silica, or zirconia, singly or in combination, promoted by an alkali metal like potassium. The first tube  208  is configured for receiving a mixture of steam and a first hydrocarbon or alcohol fuel. The first tube outlet  212  is configured for directing a first reaction reformats of the first mixture to a mixing zone  216 . The first tube  208  can be uniform in diameter, or alternatively, can be tapered such as by having a smaller diameter at the first tube inlet  210  than the diameter at the first tube outlet  212 . 
     A steam source  213  is connected to the first tube  208  by a steam tube  215 . The steam source  213  can provide a source of steam at a temperature of about 150° C. and a pressure of about 60 psia. A light fuel source  217  is connected by a light fuel tube  219  to the first tube  208  for directing light fuel into the first tube  208 . The light fuel includes a suitable fuel such as a hydrocarbon, including gasoline, JP-8, kerosene, also alcohol including methanol and ethanol. 
     A second tube  218  is annularly disposed about the first tube  208 . The second tube  218  has a second tube inlet  220  for receiving a mixture of oxygen and heavy hydrocarbon fuel. The second tube  218  also has a second tube outlet  222  for directing a second reaction reformate of a second mixture. The second tube  218  can have a uniform diameter along its length, or alternatively, a wider diameter at the lower portion  206  and narrower diameter at the upper portion  204 . The second tube outlet  222  is configured for directing a second reaction reformate of the second mixture to the mixing zone  216 . 
     Annularly disposed about the second tube  218  is a third tube  224 . The third tube  224  has a third tube inlet  226  proximate to the mixing zone  216  for receiving a mixture of the first reaction reformate of the first mixture and the second reaction reformate of the second mixture. The third tube  224  has a third tube outlet  228  for directing mixture of the first reaction reformate and second reaction reformate from the third tube  224 . The third tube  224  can include a steam reforming catalyst  225  for further reforming the hydrocarbon present in the mixture. An example of a suitable steam reforming catalyst  225  includes the same catalyst described for the steam reforming catalyst  214 . 
     A helical tube  232  extends about the length of the third tube  224 . A first end  234  of the helical tube  232  is located at an inlet housing  233 . An oxygen source  242  is connected to the inlet housing  233  by a conduit  235  with a first end inlet  236  for receiving an oxygen-containing gas from an oxygen gas zone  240 . A second end  247  of the helical tube  232  has a helical tube outlet  244  for directing oxygen containing gas into the second tube  218 . Examples of a suitable oxygen-containing gas include oxygen (O 2 ), air, etc. 
     A heavy fuel source  241  is connected by a heavy fuel tube  243  to a heavy fuel inlet  246 . The heavy fuel inlet  246  is joined to the helical tube  232  proximate to the second end  247 . Examples of suitable heavy fuels include gasoline, kerosene, JP-8, methanol and ethanol. In another embodiment, the same sources of fuel can be used for the heavy fuel (first hydrocarbon fuel) and the light fuel (second hydrocarbon fuel). Alternatively, a fractionator, as described in FIG. 2, can be used to supply a heavy fuel and a light fuel. In another embodiment, the light fuel and heavy fuel can be the same and can come from the same source. 
     A vessel  252  is annularly disposed about the third tube  224 . The vessel inlet  254  can direct reformate products from the third tube outlet  228  into the vessel  252 . The helical tube  232  is disposed between the vessel  252  and the third tube  224 , and gases from the third tube  224  can be directed through the vessel  252  from the vessel inlet  254  over and around the helical tube  232  to a vessel outlet  256 . A flow distribution region  258  conducts gas from the vessel outlet  256  to a catalyst reforming zone  260 . Additional steam can be added through a second steam inlet  257  to provide added cooling and water for reforming. 
     The catalyst reforming zone  260  is annularly disposed about the vessel  252 . The catalyst reforming zone  260  includes a catalyst  262  for further shifting the reformate to hydrogen gas. An example of a suitable catalyst  262  includes ferric oxide (Fe 2 O 3 ) and chromic oxide (Cr 2 O 3 ). Other types of high temperature shift catalysts include iron oxide and chromium oxide promoted with copper, iron silicide, supported platinum, supported palladium, and other supported platinum group metals, singly and in combination. The catalyst  262  can be in powdered form and have a height substantially the height of the vessel  252 . The catalyst reforming zone  260  is sufficiently porous to allow passage of gas from the flow distribution region  258  to an exit zone  268 . The catalyst  262  in the catalyst reforming zone  260  is held in place by a lower perforated plate  264  and an upper perforated plate  266 . Product gases of the catalyst reforming zone  260  can exit the third reformer  200  from an exit zone  268  through a reformer shell exit  270 . 
     In a third embodiment of the invention for converting hydrocarbon or alcohol fuel into hydrogen gas and carbon dioxide, a fuel is directed from the light fuel source  217  through the light fuel tube  219  to first tube inlet  210 . The steam is directed from the steam source  213  through the steam tube  215  to the tube inlet  210  into the tube  208 . The light fuel partially reacts with the steam to form a first heated reformate stream that includes hydrogen gas and carbon monoxide. The first heated reformate stream is directed from the first tube  208  through the first tube outlet  212  to the mixing zone  216 . 
     An oxygen containing gas, such as air, is directed from the oxygen source  242  through the conduit  235  to the inlet housing  233  to the oxygen gas zone  240  into the first end inlet  236  of the helical tube  232 . The oxygen containing gas, such as air, is preheated to a temperature of about 450° C. In a preferred embodiment, the air has a velocity of greater than about 40 meters per second. As oxygen containing gas is directed through the helical tube  232 , a suitable heavy fuel vapor is directed from the heavy fuel source  241  through the heavy fuel tube  243 . Examples of suitable heavy fuels include JP-8, kerosene and other hydrocarbon fuels typically used in reformers. Gaseous hydrocarbons, such as methane and propane, can also be used. The oxygen-containing gas and heavy fuel are fed at rates sufficient to mix within the helical tube  232  and spontaneously partially oxidize as the mixture enters the second tube  218  through the second tube inlet  220  to form a heated second reformate stream that includes steam, carbon monoxide and oxygen gas. In a preferred embodiment, oxygen-containing gas is tangentially directed around the interior of the second tube  218 . A hydrocarbon fuel of second mixture partially reacts to form a second heated reformate stream that includes hydrogen gas and carbon monoxide. The heat in the second tube  218  provides energy to cause the reaction to progress in the first tube  208 . 
     The fuel that is fed into the first tube  208  and the second tube  218  may or may not be about equal in amount. A second tube  218 , the partial oxidation chamber, is operated at a ratio of about two to one, fuel to oxygen gas, for example, with a temperature of about 1375° C. Heat transfer from the second tube  218  to the first tube  208  can cause partial steam reforming in the first tube  208  while the temperature is maintained at about 925° C. For liquid fuels, such as gasoline and light kerosene, the lighter fuel ends are prevaporized for delivery to the first tube  208 . Heavy fuels are burned in the partial oxidation zone where high temperature (about 1375° C.) can break down fuel with minimal carbonization. 
     The first heated reformate stream from the first tube  208  and the second heated reformate stream from the second tube  218  are directed to a first tube outlet  212  and a second tube outlet  222 , respectively, into a mixing zone  216 . The separate tubes  208 , 218  allow carbon reduced operation at high fuel to oxygen ratios of about four- or five-to-one, thereby reducing soot formation. It allows using distillate fuels, such as gasoline or kerosene, whereby heavy portion type fuels are preferentially directed to a second tube  218  for high temperature combustion necessary to break heavy molecules while light portion-type vapors are directed to a first tube  208  for partial steam reforming as a result of thermal contact with the heated combustion from the second tube  218 . The first heated reformate stream and the second heated reformate stream mix within the mixing zone  216 . The mixture is directed from the mixing zone  216  through the third tube inlet  226  into the third tube  224 . 
     In a third tube  224 , a further portion of the fuel is reformed to hydrogen and carbon monoxide to form a third tube reformate stream. The third tube reformate stream exits through a third tube outlet  228 . The third tube reformate products are directed through the vessel inlet  254  into the vessel  252  where the reformate stream passes over and around the helical tube  232  to the vessel outlet  256 . Additional steam can be added to the vessel  252  through the steam inlet  253  to provide additional cooling and further reform the hydrocarbon and carbon monoxide present in the reformate stream. The reformate stream is directed from the flow distribution region  258  through the catalyst reforming zone  260  where the reformate stream is directed through the catalyst reforming zone for further reforming the carbon monoxide into hydrogen gas and carbon dioxide to form product stream having a concentration of about 0.5 percent, by volume, carbon monoxide. The product stream exits through the exit zone  268  through the shell exit  270 . 
     Equivalents 
     Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein. Such equivalents are intended to be encompassed in the scope of the claims.