Abstract:
An apparatus designed to form syn gas from carbonaceous materials such as coal includes a devolatilization reactor in combination with a reformer reactor which subsequently forms syn gas. The reformer reactor, in turn, is in communication with a particulate separator. The devolatilization reactor is fed with material using a compression feeder which drives air from the feed material, compresses it in a feed zone forming a seal between the feed hopper and the devolatilization reactor. The reformer reactor, as well as the particulate separators, are maintained in a heated furnace so that the temperature of the formed syn gas does not decrease below the reaction temperature until particulate material has been separated.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Carbonaceous material can be reacted with steam at elevated temperatures to form syn gas, which is a combination of carbon monoxide and hydrogen. As disclosed in U.S. Pat. No. 6,863,878, if the initial reaction reaches a temperature greater than about 450° F. before the available oxygen is reacted, combustion occurs. This produces unwanted carbon dioxide, ash and slag. To avoid this, as disclosed in U.S. Pat. No. 6,863,878, the temperature must be maintained at 450° F. until after the available oxygen is reacted.  
       SUMMARY OF THE INVENTION  
       [0002]     The present invention is premised on the realization that syn gas can be produced more efficiently by modifying the process disclosed in U.S. Pat. No. 6,863,878, the disclosure of which is hereby incorporated by reference. In particular, the carbonaceous material in the devolatilization zone is maintained at a temperature less than 450° F. until all of the available oxygen is reacted. In the present invention, this material is then raised to a temperature of about 1000° F. in the devolatilization zone prior to being combined with steam to form the syn gas in the reformer reactor.  
         [0003]     From the reformer reactor, the formed syn gas passes through a series of particulate separators to remove any formed ash. These separators are maintained at a temperature greater than 1500° F., by housing them in the same furnace as the reformer reactor. This prevents unwanted reactions which can occur when the syn gas cools, and avoids carbon buildup in the apparatus. The syn gas from the separator is rapidly quenched to a temperature well below 1000° F., preferably to a temperature of about 120° F. At this temperature, the syn gas is stable and will not form carbon deposits or allow unwanted reactions. At the same time the material is cooled, preferably in a quencher, any residual tar or oil is separated and either fed back to the devolatilization zone for reaction or collected for further use. In a further feature of the present invention, the heat from the devolatilization zone is directed to a preheater section where water and combustion air are circulated to recover residual heat.  
         [0004]     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  
       [0005]      FIGS. 1A and 1B  are diagrammatic depictions of the apparatus used in the present invention;  
         [0006]      FIG. 2  is a cross sectional view of an embodiment of the feed section;  
         [0007]      FIG. 3  is a schematic elevational view of an alternate feed section; and  
         [0008]      FIG. 4  is a plan view of an auger used in the embodiment shown in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0009]     As shown diagrammatically in  FIGS. 1A and 1B , syn gas facility  10  includes a feed section  12  which communicates with a devolatilization section  14 , in turn connected to a reformer reactor  16 . The reactor  16  is designed to produce syn gas which passes through particulate separators  18  and  20 . The gas is cooled, filtered, and collected for use.  
         [0010]     As shown more particularly in  FIGS. 1 and 2 , the feed section  12  includes a hopper  38  having an auger  40 , which directs cabonaceous feed material to feed chamber  42 . The feed chamber  42  is connected to a feed tube  44  which leads to the devolatilization section  14 . Above the feed section is a cylindrical support  48  which supports a compacting cylinder  46  designed to force feed material from the feed chamber  42  into the feed tube  44 . The feed tube  44  leads to a delumper  50 , which communicates via passage  52  to the devolatilization section  14 . A gate valve  53  prevents backflow through line  55  from delumper  50 .  
         [0011]     The devolatilization section  14  includes four cylindrical reaction chambers  56 , 58 , 60  and  62 . Each reaction chamber is in communication with the next reaction chamber. Each reaction chamber includes an auger  64  which is adapted to force the feed material through the respective chambers  56 - 62  to feed auger  70 . The augers  64 , in turn, are operated by motors  68 . The feed auger  70  communicates with the feed eductor  72 . Steam from a steam heater  76  located in furnace  77  is introduced into an eductor  72  through steam inlet  74 . This forces material cycloconically through line  75  to the reactor  16 , also located in furnace  77 .  
         [0012]     The furnace  77  includes a burner  78  and a combustion outlet or plenum  80 . In addition to the reactor  16 , the furnace includes steam heater  76  and separators  18  and  20 . Combustion outlet  80  directs heated air to devolatilization zone  14 , which, in turn, communicates with a preheater  81  which ultimately communicates with a stack  82 .  
         [0013]     As shown, reformer reactor  16  is a tubular reactor which communicates with eductor  72  via line  83 . An outlet line  84  from reactor  16  leads to the first particulate separator  18 . Separator  18  includes a gas outlet line  85  which, in turn, leads to the second particulate separator  20 . Line  91  directs gas from separator  20  to a quench eductor  86  which directs gas and water through line  87  to a quench tank  88  ( FIG. 1B ). The quench eductor  86  includes a water inlet line  89 .  
         [0014]     The quench tank  88  is a gas/water/oil separator and includes a gas outlet  94 , a water outlet  96  and a tar/oil outlet  98 . The tar outlet  98 , as shown, leads to a pump  100  which directs tar and/or oil via line  102  to line  55  just upstream of delumper  50 . The water outlet  96  is directed through line  106  through a surge tank  108 .  
         [0015]     The gas outlet  94  in turn leads to a second quencher eductor  114 , which includes a water inlet  116  directed from tank  117 . The quench eductor outlet  118  in turn leads to a secondary quencher  120 . The quencher  120  includes a water outlet  122  and a gas outlet  124 , which leads to a quench scrubber  126 .  
         [0016]     The water outlet  122  leads to water line  106 , in turn leading to surge tank  108 . The quench scrubber  126  includes a water outlet  128  which goes to a drain  130 . The gas outlet  132  from the quench scrubber  126  leads to a T  134  wherein a first line  136  is directed to a water filter  137  which removes water. A gas outlet  140  from filter  137  passes to the product gas section  142 , and a water outlet  138  leads via line  128  to drain  130 . The second line  146  from T  134  is directed to a second water filter  148  which also includes a water outlet  150  which leads back to the drain  130  via line  128 . The gas outlet  152  is directed to a compressor  154  and, in turn, to a scrubber  156  to remove residual water. The scrubber  156  includes a water outlet  158  directed to either the drain or makeup water line  244 , and a gas outlet  160  which is, in turn, directed to the burner  78  where it is used to heat the furnace  77 .  
         [0017]     A make up water inlet  200  leads to the surge tank  108 . The water in tank  108  can circulate through an optional water treatment package  204 , depending on the particular water conditions, such as hardness and the like.  
         [0018]     The tank  108  includes an outlet  206  which is directed to tandem filters  208   a  and  208   b . The filters have a common outlet  210  which is directed to T  212 . One line from T  212  is directed to a first pump  214 . Pump  214  directs the water through line  213 , a filter  216  and, subsequently, to a cooler  218  which directs chilled water back to tank  108 . The second line  220  from T  212  is directed to a second T  226  which directs a portion of water to a second pump  228  which directs it to a tank  117 , which, in turn, communicates with a chiller  234 . Third pump  230  directs water from T  212  through line  89  into quench eductor  86 , as previously described.  
         [0019]     The apparatus  10  also includes a preheater section  81  which utilizes exhaust gas that has passed from the furnace  77  through the devolatilization section  14  to preheat water for the steam reactor  16 , as well as combustion air for the burner  78 . The exhaust from furnace  77  passes through exhaust plenum  80  to devolatilization section  14  and then through exhaust  240  to the preheater section  81 . Water inlet line  244  directs deionized water through the preheater section through line  246  to the steam heater  76 . A blower  250  is used to introduce air through the preheater  81 . This is exhausted via line  254  to burner  78 .  
         [0020]     In operation, feed, such as pulverized coal, is introduced through hopper  38  and feed section  12  where it is compressed by cylinder  46  and forced through valve  53  and line  55  to the delumper  50 . The feed is forced into the devolatilization section  14 . Cylinder  46  applies sufficient pressure to compress the feed material and drive out most air associated with the feed material, generally 10-20 psi or greater. This force, overcomes any pressure from the devolatilization section and causes the feed material to act as a seal between the feed section  12  and devolatilization section  14 . This removes air from the feed and prevents introduction of unwanted oxygen into the devolatilization zone.  
         [0021]     Auger  64  forces the feed through chambers  56 - 62 . The devolatilization section starts with a lower temperature first chamber  56 , followed by a higher temperature second chamber  58  and, in turn, a higher temperature third  60  and fourth  64  chamber. The temperatures of the chambers are designed so that the temperature of the feed material does not reach 450° F. until all oxygen in the feed material reacts, in order to prevent pyrolysis. Generally, the first reaction chamber will have an initial temperature of about 100° F., with the final devolatilization section at 1000° F. Most of the free oxygen will react well before the feed reaches a portion of the devolatilization section that is at 450° F. The temperature of each section is controlled by its proximity to exhaust plenum  80  as well as surface area and residence time. The pressure from the feed tube  44  through the devolatilization section  14  is about 125 psig.  
         [0022]     The end product exiting from the devolatilization section  14  is primarily char and gases liberated during devolatilization. This end product is directed to the feed auger  70  leading to steam eductor  72 . Steam from steam heater  76  is directed into the eductor  72 . The temperature of the steam should be about 1500° F. and the pressure is about 125 psi. The eductor then leads to the reformer reactor  16  wherein the syn gas is created. In the reactor  16 , the reactor temperature is increased to greater than 1500° F., preferably about 1550° F. at a pressure of about 125 psig. A portion of the reactant flow in reactor  16  can be directed through line  253  to an inlet immediately upstream of feed auger  70  to carry solids at low flow or feed rates.  
         [0023]     The reaction product from reactor  16 , ash and syn gas, is directed to cyclone separators  18  and  20 , which are located within the furnace  77  and maintained at the same temperature of the reactor  16  of about 1550° F. at 125 psi. Separators  18  and  20  remove the ash from the reaction product. The ash is directed to augers  241  and  243  which move the ash into dry ash bins  245  and  247  without permitting syn gas to escape the system.  
         [0024]     After passing through separators  18  and  20 , the syn gas flows via line  91  from the furnace to quench eductor  86  and quench tank  88  and where it is cooled to about 120° F. by water from tank  108  at about 140 psi. The temperature of the water in tank  108  is controlled by recirculation through cooling tower  218  and is preferably about 90° F. The quench tank  88  separates the gas, water, and oil. The water is directed back to tank  108  and is reused.  
         [0025]     The gas itself is then directed from the quench tank  88  to a second quench eductor  114 . Water at 200 psi from tank  117  is used to further cool the syn gas to about 70° F. at 125 psi. Chiller  234  is used to establish the water temperature at about 60° F. The cooled gas flows to the secondary quencher  120  which separates water, directing it back to tank  108 , and allows the gas to flow to quench scrubber  126 , again separating water that is sent through line  128  to the drain from the gas that is directed through filters  137  and  148 . The gas from filter  137  is collected for use. The gas from filter  148  is fed back to the burner  78  which fuels the furnace. For initial start up, a separate fuel source can be used.  
         [0026]     An alternate feeder  250  is shown in  FIGS. 3 and 4 . Feeder  250  includes a material hopper  252  having a feed auger  254  leading to feed bin  256 . Feed bin  256  includes a screw  258  rotated by motor  260 . The screw leads to feed tube  44  which connects through outlet  262  to the devolatilization section  14 .  
         [0027]     As shown in  FIG. 4 , the screw  258  has a main shaft  266  and a helical blade  268 . The outer diameter of blade  268  remains constant while the diameter of shaft  266  increases from the inlet portion  220  to the outlet portion  272 . This decreases the area between the shaft  266  and inlet tube  44 , thereby compressing the feed material as it is forced into apparatus  10 . In use, 20-50% preferably 40% compression is preferred.  
         [0028]     Thus, the present invention has many different improvements that improve the efficiency of the process disclosed in Klepper U.S. Pat. No. 6,863,878. Compressing the feed drives off unwanted air and forms an inlet seal. Further, heating the material in a devolatilization zone to 1000° F. prior to addition of steam improves the efficiency of the overall reaction and increases the reaction rate. By maintaining the separators in the furnace and maintaining their temperature, unwanted reactions are avoided, and, in particular, carbon deposition on the apparatus is minimized. The rapid quenching of the syn gas reaction product further avoids any unwanted carbon deposition or reaction products.  
         [0029]     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