Abstract:
Syngas is formed by combining a carbon source with steam at an elevated temperature in a generally horizontal reactor. The heat for the reaction is provided by a stoichiometric combustion nozzle at a first end of the horizontal reaction chamber. The carbon source is deposited downwardly into the reaction chamber where it combines with a flowing stream of hot gas formed from the stoichiometric combustion in combination with steam and additional oxygen, if necessary. This flowing stream of gas reacts with the deposited carbon feed source and is directed to a cyclone separator where the formed syngas is recovered from an upper portion of the separator and any formed ash is directed into a collection tank.

Description:
RELATED APPLICATION 
       [0001]    This application is related to and claims the benefit of U.S. Provisional Patent Application Ser. No. 61/174,036, filed Apr. 30, 2009, and U.S. Provisional Patent Application Ser. No. 61/289,643, filed Dec. 23, 2009, the disclosures of both of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Syngas is a combination of carbon monoxide and hydrogen. Although it can be formed under various conditions, it basically is formed by reacting a carbon source with steam at elevated temperatures, generally in the absence of oxygen. This causes the carbon source to react with the steam, forming carbon monoxide and hydrogen. One reactor that is particularly suited for use in the formation of syngas is Klepper, U.S. Pat. No. 6,863,878. This reactor combines char with steam at elevated temperatures. It discloses a particularly effective method to form the char without pyrolysis. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention is premised on the realization that syngas can be formed by combining a carbon source directly with a combustion stream formed by burning a fuel, preferably syngas, in the presence of oxygen, and combining the reaction product with steam and, if necessary, additional oxygen. A carbon source is combined with the steam and combustion gases to form syngas. The syngas flows directly into a cyclone separator where any unreacted ash falls to the bottom of the separator and the syngas is collected from the top. 
         [0004]    The reactor includes a horizontal reaction chamber in which the combustion gases and steam are introduced at one end to form a horizontal stream of hot gas. An auger-type mechanism can be used to introduce carbon feed material and drop this into the flowing stream of reactant gases. The horizontal reaction chamber connects to a cyclone separator along a tangent to create tangential flow of the reaction products. The bottom of the cyclone separator is directed to a collection container, preferably filled with water, to collect and quench any formed ash. A collector tube exits from the top of the cyclone separator, providing a flow passage for the formed syngas. This provides a simple, direct method to form syngas from a carbonaceous material. 
         [0005]    The objects and advantages of the present invention will be further appreciated in light of the following detailed description and drawings in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a cross sectional view of the apparatus for use in the present invention; 
           [0007]      FIG. 2  is a cross sectional view taken at lines  2 - 2  of  FIG. 1 ; and 
           [0008]      FIG. 3  is an enlarged cross sectional view of the combustion nozzle for use in the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    As shown in  FIG. 1 , a syngas reactor  10  includes a feed conveyor system  12  which leads to a horizontal reactor  14  having a combustion nozzle  16 . Nozzle  16  is adapted to heat carbon feed introduced into the horizontal reactor  14 . Horizontal reactor  14 , in turn, leads to a cylindrical residence chamber  18  which has a gas outlet  20 . 
         [0010]    The horizontal reactor  14  as shown includes a steel casing  21  and a refractory liner  22  which defines a tubular horizontal reaction area  23 . The feed conveyor system  12  directs a carbon feed through inlet  24  into this reaction area  23  immediately downstream from a combustion zone  26  immediately forward of combustion nozzle  16 . The width and length of reaction are determined by feed rate and the capacity to generate the requisite heat. 
         [0011]    Combustion nozzle  16  is attached to a first end of the horizontal reactor  14 . The combustion nozzle  16  includes a fuel inlet  28  and an oxygen inlet  30 . The oxygen inlet  30  leads to a concentric path surrounding the fuel inlet  28  and leads to a combustion chamber  34 . 
         [0012]    The nozzle further includes an oxygen steam inlet  36  which again leads to a concentric path  38  which leads to an outlet  39  immediately upstream of the combustion chamber  34 . 
         [0013]    Finally, the combustion nozzle  16  includes a steam inlet  40  which leads to a concentric path  42  which surrounds the concentric path  38  for the oxygen steam inlet  36 . This concentric path  42  is defined by an outer wall  44  which is designed to cause steam passing through the path to swirl. In particular, the wall  44  can be machined or rifled to promote swirling of the gas. 
         [0014]    In an alternate embodiment, an atomic hydrogen torch can be used to provide the heat in place of the combustion chamber. 
         [0015]    The feed conveyor system  12  includes a vertical inlet  50  which is connected to a feed source such as a devolatilization unit, as discussed hereinafter. The vertical inlet  50  includes a central auger which directs the feed in the direction of arrow  53  to a horizontal feed section  54 . The horizontal feed section  54  also includes an auger  56  which pushes the feed from the vertical inlet  50  to a vertical conduit  58  which communicates with the reaction area  23  immediately downstream of the combustion nozzle  16 . 
         [0016]    A second end  60  of the horizontal reaction area  23  leads into the resonance chamber  18 . As shown, the reaction area  23  is aligned along a tangent with the cylindrical resonance chamber  18 . As shown in  FIGS. 1 and 2 , the resonance chamber  18  has a cylindrical wall  62  and a closed top  64 . The wall has a steel casing  66  and a refractory lining  68 . A gas outlet  20  extends through the top  64  into the center  67  of the resonance chamber  18  slightly below the inlet  60  from the horizontal reaction area  23 . Also extending through the closed top  64  is a test port inlet  82 . 
         [0017]    The resonance chamber  18 , in turn, has a bottom end which is in communication with a frustoconical section  70 . Again, this section  70  has a steel casing  72  and a refractory lining  74 . Section  70  has a tapered side wall  71  and a narrowed bottom outlet  76  which is in communication with a recovery tank  78 . As shown, this recover tank is partially filled with water  80 . 
         [0018]    The feed material for the reactor  10  can be any carbonaceous material. It can be formed from organic material, polymeric material such as ground tire, wood, coal, and the like. Preferably, the feed will be a devolatilized carbon source in which reactive oxygen has been eliminated, as well as other organic components using a devolatilization reactor, such as that disclosed in U.S. Pat. No. 6,863,878, the disclosure of which is hereby incorporated by reference. This is upstream of apparatus  10  and not shown in the drawings. 
         [0019]    In operation, feed material introduced into apparatus  11  will be conveyed through the conveyor system  12  and fall into the reaction area  23  immediately downstream from the combustion nozzle  16 . The intersection of the vertical and horizontal feed conveyor provides a seal, preventing gas from flowing out the feed inlet. 
         [0020]    Syngas, and other fuel such as propane or natural gas, is introduced through the fuel inlet of the nozzle and, at the same time, oxygen is added so that stoichiometric combustion occurs at the combustion chamber. This will generate the heat necessary to cause the substoichiometic reaction of the carbon with steam and any additional oxygen as necessary to form syngas. The burner temperature should be at least 1300° F., more typically 2300° F. 
         [0021]    At the same time, the oxygen and fuel are introduced into the burner nozzle  16 , a blend of oxygen and water or steam is introduced downstream of the combustion chamber, as well as additional water/steam in the exterior portion of the reactor. The heat from the combustion raises the temperature of the water/steam enabling it to react with the carbon. The added oxygen increases the temperature of the gas stream during the reducing reaction immediately downstream of the stoichiometric combustion in the combustion chamber  34 . The added oxygen also promotes formation of carbon monoxide. Generally, the additional oxygen will be very minor, less than 1% of the water by weight. The steam swirls around, combines with the combustion products from the stoichiometric combustion and contacts the carbon source introduced through inlet  24 . 
         [0022]    It is desirable to have the temperature in the horizontal reaction chamber to be at least about 1200° F., and generally 2300° F., and up to 3000° F., or more. At 2300° F., any ash that remains from the char will be melted. 
         [0023]    The pressure in the reaction zone can be up to from atmospheric up to 1000 psig, although pressure is not a determining factor in the reactor, but is incidental to reaction conditions. 
         [0024]    The combustion at nozzle  16  creates a high velocity gas stream that will pass through the reaction chamber into the resonance chamber  18 . Chamber  18 , also maintained at least 1000° F., provides sufficient time for complete reaction. Generally, the gas will be in the reaction area  23  from about 0.1 to 0.3 seconds, with the velocity of the gas passing through the chamber about 500 to about 3000 ft/sec. 
         [0025]    The horizontal reaction area  23  is linear and its second end  60  is aligned tangentially with the cylindrical wall  62  of the residence chamber  18  causing a swirling movement of the gas around the wall  62  of the residence chamber  18 . As the reaction continues, gas is forced downwardly, and the syngas will be collected from outlet tube  20  which is directed to a collection system (not shown). 
         [0026]    The denser material formed in the reaction, primarily ash, will continue into the frustoconical section  70  and will continue downwardly into the tank  78 . This is filled with hot water which will quench the ash where it will be eventually separated. 
         [0027]    The invention will be further appreciated in light of the following detailed example. 
       EXAMPLE 
       [0028]    Using an apparatus as shown in the Figures, wherein the reaction area  23  is approximately 4 inches in diameter and 48 inches in length, raw wood as a feed material was used to produce syngas. The feed rate of the wood chips was approximately 25 pounds per hour, and the water flow rate was approximately 0.25 gph. Temperature probes located at various points along the reactor are listed, and the temperature probe for the burner was slightly upstream of the burner. Probe 1 is located immediately downstream of the burner and probe 4 is located in the residence chamber. The oxygen flow rate to the burner was 1.5 scfh, and the fuel, in this case propane gas, was 40 scfh. The secondary oxygen, which is combined with the steam through inlet  36 , was varied, as indicated in Table 1, below. This reaction was conducted over a period of an hour and 11 minutes. The gas product obtained was approximately 30% hydrogen, 32% carbon monoxide, and 27% carbon dioxide, as measured by gas chromatography. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Reading 1 
                 Reading 2 
                 Reading 3 
                 Reading 4 
                 Reading 5 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Time 
                 12:00 
                 12:25 
                 12:45 
                 1:00 
                 1:11 
               
               
                 Cyclone Temperature (° F.) 
                 600 
                 400 
                 400 
                 525 
                 670 
               
               
                 Reactor Temperature 1 (° F.) 
                 1443 
                 1456 
                 1654 
                 1760 
                 1949 
               
               
                 Reactor Temperature 2 (° F.) 
                 1390 
                 1400 
                 1616 
                 1770 
                 1949 
               
               
                 Reactor Temperature 3 (° F.) 
                 1257 
                 1229 
                 1388 
                 1550 
                 1725 
               
               
                 Reactor Temperature 4 (° F.) 
                 417 
                 462 
                 526 
                 594 
                 655 
               
               
                 Burner Temperature (° F.) 
                 1397 
                 1417 
                 1418 
                 1425 
                 1398 
               
               
                 O 2  Zone 2 flow Rate (ounces/hour) 
                 3 
                 3 
                 4 
                 6 
                 6.5 
               
               
                 Feed Chamber Pressure (psi) 
                 3 
                 3 
                 3 
                 3 
                 2 
               
               
                 Reactor Chamber Pressure (psi) 
                 3 
                 3 
                 3 
                 3 
                 1 
               
               
                 Upper Cyclone Chamber Pressure (psi) 
                 3 
                 3 
                 3 
                 3 
                 1 
               
               
                 Lower Cyclone chamber Pressure (psi) 
                 3 
                 3 
                 3 
                 3 
                 3 
               
               
                   
               
             
          
         
       
     
         [0029]    This demonstrates that the apparatus and method of the present invention efficiently produces commercially useful syngas. 
         [0030]    The reaction can be further improved by increasing burner temperature, reducing oxygen content and changing the feed material. 
         [0031]    This has been a description of the present invention along with the preferred method of practicing the present invention. However, The invention itself should only be defined by the appended claims, WHEREIN I CLAIM: