Abstract:
A gasification furnace for gasifying a biomass resource in a manner producing a low quantity of tar. The gasification furnace ( 10 ) is provided with a punching plate ( 11 ) partitioning the furnace interior into upper and lower spaces; a biomass resource supply port ( 10   a ) for supplying the biomass resource over the punching plate ( 11 ); a first oxidizer supply port ( 10   c ) and a second oxidizer supply port ( 10   d ) for supplying an oxidizer into the furnace; a first oxidizer supply path supplying the oxidizer from the first oxidizer supply port ( 10   c ) from above towards below the punching plate ( 11 ); a second oxidizer supply path distributing and supplying to a plurality of locations within a predetermined area in the vicinity of the punching plate ( 11 ) from the second oxidizer supply port ( 10   d ); and a dry distillation gas output ( 10   b ) for discharging dry distillation gas generated by the pyrolysis and partial oxidation of the biomass resource on the punching plate ( 11 ) to the outside.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a gasification furnace and a gasification system for gasifying biomass resources, and a reformer and a reforming system for reforming dry distillation gas generated from biomass resources. 
       BACKGROUND ART 
       [0002]    As is generally known, in recent years it has become a more popular practice to gasify biomass resources (biological resources such as construction debris and fragments) and use it as fuels. And gasification of biomass is usually done by downdraft type gasification furnace (see, for example, patent literature 1), or updraft type gasification furnace (see, for example, patent literature 2), however, both types of gasification furnaces produce relatively large amount of tar and clinker during gasification of biomass resources. The existing gasification furnaces are ones hard to control its furnace temperature (ones wherein thermal runaway sometimes occur). 
         [0003]    Moreover, gasification of biomass resources is usually done by reforming dry distillation gas generated by the gasification furnace in a reformer (a reforming furnace, a reforming machine). However, the existing reformers (see, for example, patent literature 2 and 3) are ones that require electrical energy or fuel in order to operate. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         Patent Literature 1: Japanese Laid-Open Patent Publication 2008-81637 
         Patent Literature 2: Japanese Laid-Open Patent Publication 2006-231301 
         Patent Literature 3: Japanese Laid-Open Patent Publication 2008-169320 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    Under such circumstances, it is a primary object of the present invention to provide a gasification furnace and a gasification system capable of reforming biomass resources in a way that produces little amount of tar and/or clinker. 
         [0008]    Further, it is a secondary object of the present invention to provide a gasification system that does not require electrical energy etc. to reform dry distillation gas. 
         [0009]    Moreover, it is a tertiary object of the present invention to provide a reformer and a reforming system that do not require electrical energy etc. to reform dry distillation gas. 
       Solution to Problem 
       [0010]    To accomplish the above primary object, a gasification furnace for gasifying biomass resources according to the present invention, includes: a punching plate dividing inside of the gasification furnace into upper and lower spaces; a biomass resource supply port supplying biomass resources on the punching plate; a first oxidizer supply port and a second oxidizer supply port each supplying oxidizer into the gasification furnace; a first oxidizer supply path supplying oxidizer, which is supplied from the first oxidizer supply port, from upper region of the punching plate downward; a second oxidizer supply path distributing oxidizer supplied from the second oxidizer supply port to a plurality of places within a predetermined area near the punching plate; and a dry distillation gas outlet discharging dry distillation gas generated by partial oxidation and pyrolysis of biomass resources on the punching plate. 
         [0011]    Namely, the gasification furnace of the present invention has such a configuration capable of supplying oxidizer onto the biomass resource (woody/herbaceous biomass fragments) while supplying oxidizer to the bottom layer of the biomass that is piled up on the punching plate. Although details (specific reason/cause of less production of tar and clinker) are not yet clear, it is understood from every type of experiment that operating gasification furnace of the above configuration while supplying heated oxidizer (air only, or air and water vapor) to the bottom layer of biomass resources piled on top of punching plate, and supplying unheated oxidizer (air for example) to the biomass resources from the top, produces less tar and clinker. Therefore, it can be said that the gasification furnace of this invention can gasify biomass resources with minimal production of tar and clinker. 
         [0012]    It is also understood that if the oxidizer amount which is supplied from the top is channeled, temperature inside furnace can be lowered rapidly. It can be said that the gasification furnace in this invention can easily control temperature inside the furnace. 
         [0013]    For the gasification furnace in this invention, as long as oxidizer which is supplied from the second oxidizer supply port can be distributed to a plurality of places in predetermined area near punching plate, various different configuration/structure can be adopted as the second oxidizer supply path. For example, it is possible to adopt, as the second oxidizer supply path, a path distributing oxidizer supplied from the second oxidizer supply port to a plurality of places in predetermined area above the punching plate and a plurality of places in predetermined area below the punching plate. Further, it is also possible to adopt, as the second oxidizer supply path, a path including a plurality of pipes each of which has a plurality of through holes on its side surface, and passes through the punching plate. 
         [0014]    The first oxidizer supply path of gasification furnace in this invention can be the through holes which is formed in the gasification furnace (furnace shell of the gasification furnace), or solid pipes. Furthermore, the punching plate for the gasification furnace in this invention do not need to be the punching plate of narrow sense, and items which can hold biomass resources in a form which allows gas to pass through (item where biomass resources do not fall off of; for example, mesh-like components) are acceptable. 
         [0015]    The punching plate for the gasification furnace in this invention can also be a tabular member. However, various experiments proved that when the thickness of the biomass resources on the punching plate is uneven (part of biomass resources on the punching plate is thicker than others), it is less likely to misfire. Therefore, for the punching plate, it is desirable to use a non-tabular member, for example, a member in a shape like side faces of a pyramid corresponding to the shape of the horizontal cross-section of the gasification furnace. 
         [0016]    Also, to accomplish the above primary object, the gasification system of the first aspect of the present invention includes: the gasification furnace according to any one of claims  1  through  6 ; a heat exchanger to generate heated air and water vapor using heat of dry distillation gas discharged from the dry distillation gas outlet of the gasification furnace; and an oxidizer supply path to supply the heated air and water vapor generated by the heat exchanger as oxidizer to the second oxidizer supply port. 
         [0017]    In other words, the gasification furnace of the present invention is used in the gasification system of the first aspect of the present invention. Therefore, this is a gasification system which can gasify biomass resources with little production of tar and clinker. Also the gasification system of the first aspect of the invention has the configuration where oxidizer which is supplied to the gasification furnace is heated by the heat of dry distillation gas discharged from gasification furnace. Therefore, the gasification system of the first aspect of this invention does not require electrical energy to heat oxidizer. 
         [0018]    For the heat exchanger in the gasification system of the first aspect of this invention, various different configurations can be adopted. For example, as the heat exchanger, it is possible to adopt a unit formed by connecting a plurality of unit heat exchangers each having an inlet and an outlet of heating object and an inlet and an outlet of heat source gas so that the dry distillation gas discharged from the gas release outlet of the gasification furnace passes through the unit heat exchangers one after another, and by connecting inlets of some of the plurality of the unit heat exchangers to outlets of rest of the plurality of the unit heat exchangers so that the some of unit heat exchangers function as means for generating heated air and the rest of the unit heat exchangers function as means for generating water vapor. By adopting such heat exchanger (by providing unit heat exchangers for such heat exchanger), the gasification systems of various specifications with different oxidizer (air, water vapor) amount and temperatures requirement can be made cheaply. 
         [0019]    Moreover, adding a reformer which reforms dry distillation gas discharged from the gas exhaust outlet and supplies it to the heat exchanger to the gasification furnace, leads to the system which produces less tar and clinker during gasification of biomass resources. 
         [0020]    Further, the gasification system of the second aspect of the invention includes: the gasification furnace according to claims  1  through  6 ; and a reformer to reform dry distillation gas discharged from the dry distillation gas outlet of the gasification furnace using heated air generated by the heat of the dry distillation gas. 
         [0021]    That is to say, in the gasification system of the second aspect of this invention, the gasification furnace of the preset invention and the reformer which reforms dry distillation gas discharged from the gasification furnace using heated air generated by the heat of the dry distillation gas. Therefore, this gasification system can gasify biomass resources with little production of tar and clinker, and at the same time does not require electrical energy for reforming gas. 
         [0022]    Note that, as the reformer in the gasification system of the second aspect, it is possible to adopt a unit including: a reformer vessel of hollow construction and having a dry distillation gas inlet to which dry distillation gas discharged from the gas outlet of the gasification furnace is input and dry distillation gas outlet from which the reformed dry distillation gas is discharged; a plurality of heat receiving pipes attached to the reformer vessel so that their upper parts make a plane nearly level to a mounting surface of the reformer and they pass through the reformer vessel; an air inlet connected with one end of each of the heat receiving pipes; a punching plate for holding heat storage material which is installed on parts of the plurality of the heat receiving pipes, the parts being in the reformer vessel; heat storage material placed on top of the punching plate for holding heat storage material; a plurality of hot air exhaust pipes each having portion that is kept in a space of the reformer vessel over the punching plate for holding heat storage material, the portion having a plurality of through holes in its pipe wall; and a connecting part connecting the plurality of the hot air exhaust pipes and the plurality of the heat receiving pipes so to allow air which pass through the plurality of the heat receiving pipes is discharged from each through hole of each hot air exhaust pipe. 
         [0023]    To accomplish the above tertiary object, a reformer for reforming dry distillation gas of the present invention, includes: a reformer vessel; a dry gas inlet for introducing dry distillation gas into the reformer vessel, a reformed gas outlet for discharging reformed gas defined as the dry distillation gas after being reformed, an oxidizer inlet for introducing oxidizer into the reformer vessel, each of which are provided on the reformer vessel; a heat exchanger to heat oxidizer introduced through the oxidizer inlet by transferring heat of the dry distillation gas from the oxidizer inlet while the dry distillation gas introduced from the dry distillation gas inlet and oxidizer introduced through the reformer oxidizer inlet do not come in contact with each other; and an oxidizer discharge part for discharging oxidizer heated by the heat exchanger into the reformer vessel. 
         [0024]    In other words, the reformer of the present invention has such a configuration that it generates high temperature oxidizer (such as heated air) which is necessary for reforming dry distilled gas (to burn part of dry distilled gas) by using heat of dry distilled gas which is to be reformed. The reformed gas/dry distillation gas by nature requires cooling. Therefore, this reformer does not require electrical energy for reforming dry distillation gas, and will be able to reform dry distillation gas by utilizing the heat of reformed gas/dry distillation gas. 
         [0025]    The reformer of this invention can be made in different configurations with varying details. For example, the reformer of the invention can be made as a device with a common heat exchanger configuration (the device that, however, discharges heated matter into the heat exchanger itself instead of discharging it to the outside of the heat exchanger). 
         [0026]    Further, the reformer of the present invention can be actualized as a device that includes the heat exchanger having: a plurality of heat receiving pipes attached to the reformer vessel so that their upper parts make a plane nearly level to a mounting surface of the reformer and they pass through the reformer vessel; a punching plate for holding heat storage material which is installed on parts of the plurality of the heat receiving pipes, the parts being in the reformer vessel; and heat storage material placed on the punching plate for holding heat storage material, and the oxidizer discharge part having: a plurality of hot air exhaust pipes each having portion that is kept in a space of the reformer vessel over the punching plate for holding heat storage material, the portion having a plurality of through holes in its pipe wall; and a connecting part connecting the plurality of the hot air exhaust pipes and the plurality of the heat receiving pipes so to allow air which pass through the plurality of the heat receiving pipes is discharged from each through hole of each hot air exhaust pipe. 
         [0027]    It should be noted that, the reformer of the present invention can also be actualized as a device that us used to feed normal temperature oxidant through oxidizer inlet. However, when the reformer of this invention is actualized in such way, dry distillation gas/reformed gas normally travels less freely inside (when pressure loss on dry distillation gas/reformed gas is relatively large; when connected to gasification furnace, dry distillation gas is not released easily from gasification furnace). 
         [0028]    On the other hand, dry distillation gas/reformed gas will flow more freely inside the reformer, if the reformer according to claim  1  or  2  is used together with a heat exchanger to heat oxidizer using heat of reformed gas discharged from the reformed gas outlet in the reformer; and an oxidizer pass to supply oxidizer heated by the heat exchanger into the reformer through the oxidizer inlet. 
         [0029]    Therefore, it can be said that the reformer of the present invention is one that is preferable to use as a component of a reformer system with such configuration. 
       Advantageous Effects of Invention 
       [0030]    According to the present invention, it is possible to provide the gasification furnace and gasification system which can gasify biomass resources with little production of tar and/or clinker, and it is also possible to provide the gasification system which does not require electrical energy etc. for reforming dry distillation gas. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0031]      FIG. 1  is an explanatory diagram of gasification system according to one embodiment of the present invention. 
           [0032]      FIG. 2  is a diagram of gasification furnace of a gasification system according to the embodiment. 
           [0033]      FIG. 3  is a cross-sectional view of arrow A-A in  FIG. 2 . 
           [0034]      FIG. 4  is a diagram of reformer in gasification system according to the embodiment. 
           [0035]      FIG. 5  is an explanation of internal configuration of a reformer. 
           [0036]      FIG. 6  is a diagram of heat exchanger which is equipped in gasification system according to the embodiment. 
           [0037]      FIG. 7  is an explanatory diagram of a modified example of the reformer according to the embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0038]    An embodiment of the present invention will hereinafter be described in depth with reference to the drawings. 
         [0039]    To start with, outlines of a gasification system and a reforming system according to one embodiment of the present invention will be described with reference to  FIG. 1 . 
         [0040]    The gasification system according to the present embodiment is so-called a biomass power generator system. As shown in Figure, the gasification system includes a gasification furnace  10 , a reformer  20 , a heat exchanger  30 , a control device  40 , a feedstock supply system  50 , a cooling system  55 , a gas reservoir  60  and a power generator  65 . Further, the gasification system contains the reforming system according to the present embodiment, which consists of the reformer  20 , the heat exchanger  30 , and a heated air path connecting heated air supply port  20   c  of the reformer  20  and air inlet  30   c  of the heat exchanger  30 . 
         [0041]    The Feedstock supply system  50  is a system that consists of a crusher which crushes woody/herbaceous biomass which is transported by trucks, a main hopper which holds woody/herbaceous biomass (hereafter called feedstock) which is crushed by the crusher, a supply mechanism for supplying feedstock within the main hopper to the gasification furnace  10 , and so on. Main components of the supply mechanism of this feedstock supply system  50  are chain conveyers, bucket elevators and screw conveyers which can be controlled by the control device  40 . 
         [0042]    The gasification furnace  10  is a unit that gasifies feedstock supplied from the feedstock supply system. This gasification furnace  10  includes a feedstock supply port  10   a  from which feedstock is supplied into the furnace (into the furnace shell), and a dry distillation gas outlet  10   a  from which dry distillation gas generated from feedstock is discharged. The gasification furnace  10  also includes a first oxidizer supply port  10   c  from which air (unheated air in this embodiment) is supplied to the furnace, and a second oxidizer supply port  10   b  from which heated air and water vapor are supplied into the furnace. 
         [0043]    The reformer  20  is a unit that reforms dry distillation gas discharged from the dry distillation gas outlet  10   b  of the gasification furnace  10 . The reformer  20  includes a dry distillation gas inlet  20   a  connected to the dry distillation gas outlet  10   b  of the gasification furnace  10 , and a reformed gas outlet  20   b  that is an outlet of reformed gas (reformed dry distillation gas). The reformer  20  also includes a heated air supply port  20   c  that is an inlet of heated air for reforming (combusting partially) dry distillation gas. 
         [0044]    The heat exchanger  30  is a unit that generates heated air and water vapor using the heat of dry distillation gas from the reformer  20 . The heat exchanger  30  includes a reformed gas inlet  30   a  connected to the reformed gas outlet  20   b  of the reformer  20 , a reformed gas outlet  30   b  for discharging reformed gas outside of reformer  20 , an air inlet  30   c , a heated air outlet  30   d , a water inlet  30   e , and a water vapor outlet  30   f.    
         [0045]    As shown in the Figure, the heated air outlet  30   d  of the heat exchanger  30  is connected to each of the second oxidizer supply port  10   d  of the gasification furnace  10  and the heated air inlet  20   c  of the reformer  20  by pipes having flow control valves. The water vapor outlet  30   f  is connected to the second oxidizer supply port  10   d  of the gasification furnace  10  by pipes having flow control valves. 
         [0046]    The water inlet  30   e  of the heat exchanger  30  is connected to a water tank (not shown) through a pipe (not shown) with a pump. The air inlet  30   c  of the heat exchanger  30  is connected to a blower (a fan; not shown) through a pipe. 
         [0047]    The control device  40  is a device (a so-called sequencer in this embodiment) that controls the supply mechanism of the feedstock supply system  50 , each of the flow control valves of this system, based on output (TCs in  FIG. 1 ) of temperature sensors  42  (see  FIGS. 2 and 4 ), which are installed at various places in the system, so that feedstock gasification and dry distillation gas reforming will operate properly. 
         [0048]    The cooling system  55  is a system that cools reformed gas discharged from the reformed gas outlet  30   b  of the heat exchanger  30 . The gas reservoir  60  is a vessel that stores reformed gas cooled by the cooling system  55 , and the generator  65  is a unit (a so-called gas engine generator) that generates power based on reformed gas in the gas reservoir  60 . 
         [0049]    Based on the premise of what has been described so far, the configuration of the gasification system according to the present embodiment will be specifically explained. Note that, among components of the gasification system of this embodiment, the feedstock supply system  50 , the cooling system  55 , the gas reservoir  60  and the power generator  65  are also used in gasification system (biomass generator systems) already in existence. For this reason, explanation only to the configurations of other components of the gasification system according to this embodiment will be given below. 
         [0050]    First, the configuration of the gasification furnace  10  will be described with reference to  FIGS. 2 and 3 . Note that,  FIG. 3  is a cross-section view of arrow A-A in  FIG. 2 . In these Figures and each of the Figures which will be used below, scale of measurement, number and location of each part have been modified arbitrarily to make each part of the gasification furnace  10  easy to recognize. 
         [0051]    As obvious from  FIGS. 2 and 3 , the gasification furnace  10  is a unit with a shape like a regular rectangular prism tapered off at the top and the bottom. Further, the gasification furnace  10  ( FIG. 2 ) is a unit wherein the above mentioned feedstock supply port  10   a  and first oxidizer supply port  10   c  are fixed on its upper part (top surface), and the above mentioned dry distillation gas outlet  10   b  and second oxidizer supply port  10   d  are fixed on its lower part (bottom surface). 
         [0052]    In the gasification furnace  10 , a punching plate  11  having a plurality of through holes (8 mm diameter holes in this embodiment) is set so as to separate the inner part of the furnace into upper and lower spaces. This punching plate is shaped like side faces of a square pyramid (4 faces of a square pyramid except the Bottom). The punching plate  11  also has a plurality of through holes (see  FIG. 3 ) to which perforated pipes  13  (details of which will be described later on) are inserted. 
         [0053]    In the gasification furnace  10 , set is a second oxidizer supply path that includes, as main components, a large and a small circular pipes  12 , the plurality of perforated pipes  13  in communication with each circular pipe  12 , and connecting pipes which connect each circular pipe  12  to the second oxidizer supply port  10   d.    
         [0054]    Each perforated pipe  13  configuring the second oxidizer supply path is a pipe-shaped member whose side surface (pipe wall) has a plurality of through holes and whose one end (upper edge of  FIG. 2 ) is sealed. As each perforated pipe  13 , a pipe whose length is determined based on the thickness D of the feedstock on the punching plate  11  during continuous operation of the system (in this embodiment, a pipe whose part above the punching plate  11  has a length of approximately 0.6×D). 
         [0055]    Each circular pipe  12  is a member manufactured by processing a pipe with a plurality of through holes on side surface into a square shape and connecting both ends of the processed pipe. Each circular pipe  12  has a plurality of through holes for installing perforated pipe  13  as illustrated in  FIG. 2  and through holes for installing connecting pipes mentioned above. And, the second oxidizer supply path consists of combination of parts of such shapes, that is for distributing and supplying oxidizer (heated air and water vapor in this embodiment) which is supplied to the second oxidizer inlet  10   d  to a plurality of places in predetermined area near the punching plate  11 . 
         [0056]    The gasification furnace  10  is connected to a rotary feeder  44  in order to throw feedstock from the feedstock supply system  50  into the feedstock supply port  10   a  (to throw feedstock into gasification furnace  10  with pressure difference). Further, the gasification furnace  10  includes pipe for introducing oxidizer into the furnace (unheated air in this embodiment) which is supplied to the first oxidizer inlet  10   c . In addition, the gasification furnace  10  includes a member (not shown) for evenly distributing air from the pipe and feedstock from the feedstock supply port  10   a  to each place on the punching plate  11  and each place of the feedstock on the punching plate  11 . 
         [0057]    The gasification furnace  10  includes an ignition port  10   e  on a specific side wall (on left side wall in  FIG. 2 ). The gasification furnace  10  is also equipped with an ignition mechanism (not shown) which is controlled by control device  40 , which introduces igniting agent (solid methanol), through this ignition port  10   e , onto the feedstock which is on the punching plate  11 . 
         [0058]    The gasification furnace  10  has an ash removal screw  16  on the bottom for removing ash generated by gasification of feedstock out of the furnace. The gasification furnace is also equipped with a plurality of temperature sensors that measure temperatures of each area inside the furnace. 
         [0059]    The gasification furnace  10  according to the present embodiment has configuration as explained, and is coated with flocculent heat-resistant material (ceramic blanket) to minimize losing heat inside the furnace. 
         [0060]    Next, a description is given of the configuration of the reformer  20  using  FIGS. 4 and 5 . 
         [0061]    The reformer  20  ( FIG. 4 ) is a unit that consists of the reformer vessel  20 ′, a plurality of heat receiving pipes  22 , a plurality of hot air exhaust pipes  23 , etc. 
         [0062]    The reformer vessel  20 ′ is a vessel in a shape like a hollow rectangular parallelepiped having tapered off lower edge. As shown in  FIG. 4 , this reformer vessel  20 ′ is a unit wherein the dry distillation gas inlet  20   a  is provided near the bottom, and the reformed gas outlet  20   b  is provided at a position higher than the reformed gas inlet  20   a.    
         [0063]    The heat receiving pipes  22  are pipes each of which is installed so as to pass through the reformer vessel  20 ′. The heat receiving pipes  22  are also installed so that their upper parts forms a plane nearly level to the mounting surface of the reformer  20 . 
         [0064]    One opening of each heat receiving pipe  22  is connected to a header  21   a  which includes a heated air inlet  20   c , and the other opening of each heat receiving pipe  22  is connected to a header  21   b.    
         [0065]    Each hot air exhaust pipe  23  is a pipe installed, inside reformer vessel  20 ′, higher than each heat receiving pipe  22  and lower than bottom end of reformed gas outlet  20   b , running through reformer vessel  20 ′. Each hot air exhaust pipes  23  (see  FIG. 5 ) inside reformer vessel  20 ′ form through holes in various places. 
         [0066]    One opening of each hot air exhaust pipe  23  is sealed with a pipe end closure flange, and the other opening of each hot air exhaust pipe  23  is connected to the header  21   b  via a header  21   c.    
         [0067]    The punching plate  24  (see  FIG. 5 ) with a plurality of through holes  25   a  are installed on the plurality of the heat receiving pipes  22  inside reformer vessel  20 ′. In space above the punching plate  25  in the reformer vessel  20 ′ is filled with enough heat storage material to bury each hot air exhaust pipe  23 . This heat storage material is for uniformizing the temperature distribution within the reformer vessel  20 ′ and removing impurities in the reformed gas (and also dry distillation gas during reforming). Therefore, heat storage material with high specific heat, high heat resistance, which are highly resistant to acidic gases such as acetic acid, tar and H 2 S, are desired. Because heat storage material which is not of cement, and which has less pressure loss are desirable, hollow cylindrical ceramic components, etc. are used. 
         [0068]    The reformer vessel  20 ′ is equipped, at the bottom, with an ash removal screw  26  to remove ash generated by gasification of feedstock out of the furnace. Moreover, the reformer vessel  20 ′ is also equipped with two temperature sensors to measure temperatures of section where heat storage material is filled in the reformer  20  (the reformer vessel  20 ′). 
         [0069]    Next, the configuration of the heat exchanger  30  will be described. 
         [0070]    As shown in  FIG. 6 , the heat exchanger  30  is a unit that is made by connecting five numbers of the unit heat exchangers each of which has an inlet and an outlet for heat object and an inlet  31   x  (x=a or b) and an outlet  31   y  (y=b or a) for heat source gas, so that reformed gas which discharged from reformer  20  passes through each of the unit heat exchanger one after another. Further, the heat exchanger  30  is also a unit that is made by connecting the outlets  31   y  for heated object of some unit heat exchangers  31  to the inlets  31   x  for heated objects of other unit heat exchangers so that two unit heat exchangers  31  in the back function as “means for generating heated air, having the air inlet  30   c  and the heated air outlet  30   d ”, and three unit heat exchangers  31  in the front function as “means for generating water vapor, having the water inlet  30   e  and the water vapor outlet  30   f”.    
         [0071]    In advance of a detailed discussion on functions of control device  40 , the reason why the gasification furnace  10 , the reformer  20  and the heat exchanger  30  of above configuration are used in the gasification system of the present embodiment. 
         [0072]    The configuration of the above gasification furnace  10  is thought of based on the knowledge obtained by every type of experiment that “by supplying relatively high temperature oxidizer on lower layer of feedstock on the punching plate and supplying unheated oxidizer (air, for example) to the feedstock from top, it is possible to gasify feedstock (biomass resources) with minimal production of tar and clinker.” Even though the reason why using the above configuration can gasify feedstock with minimal production of tar and such has not been determined, the fact that this configuration makes it easier for gas to pass through gasifying feedstock, and the fact that this configuration makes it easier to control temperature by controlling the amount of oxidizer it supplies, better than gasification furnace with only 1 oxidizer supply port, may be the causes. 
         [0073]    However, if the oxidizer which is supplied to gasification furnace  10  is heated by electric heater, electric energy output amount of the gasification system would be short of the amount of electric energy necessary to heat oxidizer. Also when using electric heater for reforming dry distillation gas discharged from gasification furnace  10 , electric energy output of the gasification system would be also short of the amount of electric energy necessary for reforming (heating) reformed gas. 
         [0074]    Meanwhile, when heating of oxidizer and reforming of dry distillation gas is performed using heat of dry distillation gas discharged from the gasification furnace  10 , it is possible to achieve a gasification system without such problems as mentioned above. For this purpose, the gasification system according to the present embodiment employs the heat exchanger  30  ( FIG. 6 ) to generate water vapor and heated air which are supplied to the gasification furnace  10 , by using heat generated by dry distillation gas in the heat exchanger  30 . Further, the gasification system of the embodiment employs the heat exchanger  30  ( FIG. 4 ) which reforms dry distillation gas from the gasification furnace  10  using heated air generated by the heat exchanger  30 , more specifically, the reformer  20  which heats heated air generated by the heat exchanger  30  using dry distillation gas from the gasification furnace  10 , and then reforms dry distillation gas from the gasification furnace  10  using re-heated air. 
         [0075]    Next, the control mechanism by control device  40  for gasification system will be explained. 
         [0076]    When continuous operation (steady operation) of the gasification system is performed, the control device  40  controls the supply mechanism in the feedstock supply system  50  so that feedstock can be supplied into the gasification furnace  10  at a predetermined speed. Further, the control device also controls each flow control valve in the system so that each temperature (mainly TC 1 -TC 7  in  FIGS. 2 and 4 ) in the system is within a predetermined temperature range. 
         [0077]    The process (hereinafter called the flow control valve process for continuous operation) that the control device  40  performs is a process of controlling each flow control valve in the system so that the temperature TC 5  can remain within 850° C.-900° C., and the temperature TC 6  remains within 1050° C.-1100° C. 
         [0078]    More specifically, the flow control valve process for continuous operation is a process of controlling each flow control valve so that heated air can be supplied from the second oxidizer supply port  10   d  at the air ratio of 0.3-0.4, and more air can be supplied than heated air from the first oxidizer supply port  10   d . And heated air (in other words, heated air generated by heat exchanger  30  that is supplied with reformed gas of 1050° C.-1100° C.) is at 400° C.-550° C. 
         [0079]    The flow control valve process for continuous operation is also, as a general rule, to adjust TC 5  by controlling the amount of air supply from the first oxidizer supply port  10   d.    
         [0080]    When making the gasification system start to gasify feedstock, the control device  40 , at first, controls the supply mechanism in the feedstock supply system  50  so that a specific amount of feedstock is supplied to the gasification furnace  10 . Next, the control device  40  introduces approximately 100 g of solid methanol into the gasification furnace  10 , by controlling ignition mechanism installed at the ignition port  10   e  of the gasification furnace  10 . The control device  40  also controls a blower connected to the first oxidizer supply port  10   c  so that air is supplied to the gasification furnace  10  from the first oxidizer supply port  10   c.    
         [0081]    Thereafter, the control device  40  starts a process of monitoring temperature (TC 1  in  FIG. 2 ) detected by temperature sensor  42  which is installed at the highest part of the gasification furnace  10  so to achieve a first specific temperature which is predetermined as a temperature when combustion (partial combustion) of feedstock in the gasification furnace  10  progresses to a certain extent. 
         [0082]    When it is detected that TC 1  reached the first specific temperature, the control device  40  controls each flow control valve for heated air and water vapor so that heated air from heat air outlet  30   d  and water vapor from water vapor outlet  30   f  of the heat exchanger  30  are supplied to the second oxidizer supply port  10   d.    
         [0083]    Then, the control device  40  starts to monitor temperature TC 5  of dry distillation gas discharged from the gasification furnace  10  to achieve a predetermined second specific temperature, and when TC 5  reaches the second specific temperature, it increases the amount of air supplied to the gasification furnace  10  from the first oxidizer supply port  10   c.    
         [0084]    Note that, the status where TC 5  reaches the second specific temperature is a status where pyrolysis zone is not formed (status where lower part of the feedstock on the punching plate  11  is oxidative decomposition zone, and upper part is dry heat zone) in the feedstock on the punching plate  11 . 
         [0085]    Thereafter, the control device  40  starts monitoring temperatures TC 1 -TC 5  at each place in the gasification furnace  10 , so temperature in the feedstock indicates pyrolysis zone is formed on the punching plate  11 . Then, when temperatures TC 1 -TC 5  reach such temperature, the control system  40  starts continuous operation control process (includes the flow control valve process for continuous operation already explained) so that continual gasification of feedstock is performed by supplying feedstock at a specific temperature. 
         [0086]    &lt;&lt;Variations&gt;&gt; 
         [0087]    The above gasification system according to the embodiment, can have variations of every type. For example, the gasification furnace  10  can be modified into a furnace that has the punching plate  11  having a tabular shape. However, various experiments proved that when the thickness of the feedstock (biomass resources) on the punching plate  11  is uneven (part of biomass resources on the punching plate is thicker than others), it is less likely to misfire. Therefore, for the punching plate  11 , it is desirable to use a non-tabular component such as the punching plate  11  described above. 
         [0088]    Further, the gasification furnace  10  can be modified to be equipped with cylindrical gasification furnace. However, square prism shape gasification furnace can introduce more feedstock inside, therefore, the shape described above is desirable for gasification furnace  10 . 
         [0089]    Although it won&#39;t be able to utilize heat energy of dry distillation gas generated by the gasification furnace  10 , the gasification system can be modified into a system in which a reformer which requires electrical energy in order to operate is use instead of the reformer  20 , or into a system which uses electrical energy to heat oxidizer supplied to the gasification furnace  10 . The gasification system can also be modified into a system for producing methanol, etc. 
         [0090]    The reforming system (the system which consists of the reformer  20 , the heat exchanger  30 , and the heated air path connecting them) according to the embodiment described above can have variations of every type. For example, the reformer  20  can be modified into a unit to which air of normal temperature can be supplied. Note that, such modification of the reforming system  20  can be achieved, for example, as illustrated in  FIG. 7 , by introducing air supplied through the air supply port  20   c  from the hot air exhaust pipe  23  into the reformer vessel  20 ′ after passing through a plurality of ( 2  in the figure) the heat receiving pipes  22  which runs across reformer vessel  20 ′. 
         [0091]    Moreover, the reformer  20  can be modified into a unit that doses not to have heat storing material (a unit having the same configuration as that of a common heat exchanger). However, having heat storing material built in equalizes each temperature within the reformer vessel  20 ′, and also prevents through holes of hot air exhaust pipe  23  from getting clogged with impurities in reformed gas. Therefore, the reformer  20  can vary from configuration described above in detail, but having heat storing material built in is preferable. 
         [0092]    It is also understandable that reforming system can be paired with downdraft/updraft type gasification furnace, and the reforming system can be used in the gasification system for producing methanol, etc. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               10  gasification furnace 
               10   a  feedstock supply system 
               10   b  dry distillation gas outlet 
               10   c  first oxidizer supply port 
               10   d  second oxidizer supply port 
               10   e  ignition port 
               11 ,  25  punching plate 
               11   a ,  25   a  through hole 
               12  circular pipe 
               13 ,  23  pipe 
               20  reformer 
               20 ′ reformer vessel 
               20   a  dry distillation gas inlet 
               20   b ,  30   b  reformed gas outlet 
               20   c  heated air supply port 
               21   a ,  21   b ,  21   c  header 
               22  heat receiving pipe 
               23  hot air exhaust pipe 
               30  heat exchanger 
               30   a  reformed gas inlet 
               30   c  air inlet 
               30   d  heated air outlet 
               30   e  water inlet 
               30   f  water vapor outlet 
               31  unit heat exchanger 
               40  the control device 
               42  temperature sensor 
               44  rotary feeder 
               50  feedstock supply system 
               55  cooling system 
               60  gas reservoir 
               65  generator