Patent Abstract:
Provided is a vertical pulverizing apparatus capable of suppressing abrasion of throat vanes ( 40 ) and elongating their abrasion resistant lives to thereby increase working efficiency. The vertical pulverizing apparatus is characterized in that: a throat ( 4 ) is provided between a housing ( 32 ) and a pulverizing table ( 2 ) and has an annular flow channel which is surrounded by a throat inner peripheral wall ( 41 ) and a throat outer peripheral wall ( 42 ) and which is partitioned by a large number of throat vanes ( 40 ); and a slope part ( 43   a,    43   b ) extending diagonally downward from an inner peripheral wall surface of the housing ( 32 ) toward a top end of the throat outer peripheral wall ( 42 ) and a horizontal part ( 44 ) extending from a bottom end of the slope part ( 43   b ) continuously to the top end of the throat outer peripheral wall ( 42 ) are provided so that top end surfaces ( 40   a ) of the throat vanes ( 40 ) and a top surface of the horizontal part ( 44 ) can be set at the same height.

Full Description:
TECHNICAL FIELD 
     The present invention relates to a vertical pulverizing apparatus capable of pulverizing solid matter such as coal or cement by means of a pulverizing table and a pulverizer such as a pulverizing roller rolling on the pulverizing table, and adjusting the pulverized particles to a predetermined particle size distribution by means of a classification portion. Particularly, it relates to the structure of the vicinities of a throat portion. 
     BACKGROUND ART 
     Vertical pulverizing apparatuses are used as fuel supply units in coal fired boiler plants for thermal power generation in which pulverized coal is burned as fuel. 
       FIG. 7  is a schematic configuration view of a background-art vertical pulverizing apparatus. As shown in  FIG. 7 , the vertical pulverizing apparatus is mainly constituted by a drive portion A, a pulverization portion B, a classification portion C and a distribution portion D, and the portions have a layout as illustrated. 
     The drive portion A has a mechanism in which torque is transmitted to a pulverizing table reduction gear  50  from a pulverizing table driving motor  51  placed outside the vertical pulverizing apparatus, and torque of the reduction gear  50  is transmitted to a pulverizing table  2  placed in an upper part of the drive portion A. 
     In the pulverization portion B, a plurality of pulverizing rollers  3  disposed circumferentially at equal intervals on the pulverizing table  2  are supported by a pressure frame  5 , roller pivots  7  and roller brackets  6 . The pressure frame  5  disposed inside the vertical pulverizing apparatus is pulled downward through a pressure rod  8  by a pressure device  9  such as a hydraulic cylinder placed outside the vertical pulverizing apparatus, so that a pulverization load can be applied to the roller brackets  6  placed under the pressure frame  5 . 
     Due to the rotation of the pulverizing table  2 , the pulverizing rollers  3  rotate together with the pulverizing table  2 . Coal  60  inputted through a coal feeding pipe  1  is pulverized by a meshing part between the pulverizing table  2  and each pulverizing roller  3 . 
     The classification portion C is placed above the pulverization portion B and provided with a rotary type classification mechanism  20  having a large number of rotary fins  21 . The rotary fins  21  are disposed circumferentially at equal intervals around a hollow rotation shaft  22  disposed on the outer side of the coal feeding pipe  1 , and supported by the rotation shaft  22 , so that the rotary fins  21  can be rotationally driven through the rotary shaft  22  by a rotary fin driving motor  23 . 
     On the radially outer side of the rotary fins  21 , a plurality of fixed fins  12  are disposed circumferentially at equal intervals. The fixed fins  12  are hung on a ceiling part  10  of the vertical pulverizing apparatus. A cone-shaped recovery hopper  11  is coupled to the bottoms of the fixed fins  12 . A bottom end opening part (not shown) of the recovery hopper  11  is opened toward the top surfaces of the center portions of the pulverizing rollers  3 . 
     The distribution portion D is placed above the rotary type classification mechanism  20  and constituted by a distributor  33  and a plurality of distribution pipes  34  extending toward a boiler apparatus. 
     Incidentally, the reference numeral  4  in  FIG. 7  represents a throat provided in the outer periphery of the pulverizing table  2 ;  30 , a primary air duct;  31 , a primary air wind box; and  32 , a housing which receives various members. 
     Next, the operation of the vertical pulverizing apparatus will be described. 
     The coal  60  fed from the coal feeding pipe  1  falls down to the central part of the pulverizing table  2  as shown by the arrow. The pulverizing table  2  is rotationally driven through the reduction gear  50  by the driving motor  51 . The coal  60  falling down onto the pulverizing table  2  is moved on the pulverizing table  2  toward the outer peripheral part thereof while drawing a spiral locus due to centrifugal force caused by the rotation. Then, the coal  60  is bitten and pulverized between the pulverizing table  2  and each pulverizing roller  3 . 
     A group of particles  62  produced by the pulverization are blown upward above the pulverizing table  2  by conveying primary air  61  introduced from the throat  4  provided in the outer periphery of the pulverizing table  2 . Of the group of particles  62  blown upward, particles with a large particle size fall down by gravity on the way of being conveyed to the classification portion C, and are returned to the pulverization portion B (primary classification). 
     The group of particles  62  arriving at the classification portion C are classified into fine particles  63  which are not larger than a predetermined particle size and coarse particles  64  which are larger than the predetermined particle size by the fixed fins  12  and the rotary fins  21  (secondary classification). The coarse particles  64  recovered by the recovery hopper  11  fall down to the pulverization portion B and are pulverized again. On the other hand, the fine particles  63  passing through the fixed fins  12  and the rotary fins  21  are distributed to the plurality of distribution pipes  34  in the distributor  33 , and conveyed to a burner of a not-shown boiler apparatus in the form of a vapor phase. 
     An example of the throat  4  in the background-art vertical pulverizing apparatus is shown in  FIG. 8  and  FIG. 9 .  FIG. 8  is a sectional view showing the vicinities of the throat  4 , and  FIG. 9  is a development view of the throat  4 . 
     As shown in  FIG. 8 , the throat  4  is an annular flow channel surrounded by a throat inner peripheral wall  41  and a throat outer peripheral wall  42 . In order to enhance the primary classification, a large number of throat vanes  40  inclined at a desired angle α with respect to a rotation direction X of the pulverizing table  2  are placed at intervals in the circumferential direction of the throat  4  so as to give a turning force to the primary air  61  jetted from the throat  4 . 
     An annular slope part  43  is placed between the housing  32  and the throat outer peripheral wall  42  so as to be lowered from the housing  32  toward the throat outer peripheral wall  42 . Although the throat  4  is a rotary type throat rotating together with the pulverizing table  2  in this example, a fixed type throat attached to the housing  32  may be used as the throat  4 . 
     When a flammable material such as coal which is pulverized by the vertical pulverizing apparatus is deposited locally inside the vertical pulverizing apparatus, there is a danger that the deposited flammable material may be heated by the high-temperature primary air  61  supplied from the throat  4 , resulting in ignition. 
     Therefore, as shown in  FIG. 8 , the slope part  43  is provided so that particles  68  falling down along the inner peripheral wall surface of the housing  32  can be moved to the top of the throat  4  quickly without being deposited. It is generally thought that the slope angle of the slope part  43  has to be made not smaller than 30 degrees in view of the repose angle of powder. 
     It is also thought that it is desirable that the throat inner peripheral wall  41  and the throat outer peripheral wall  42  are inclined toward the central axis of the vertical pulverizing apparatus. This is to vertically blow particles supplied from the pulverizing table  2  to the top of the throat  4 . That is, inward momentum is given to the primary air  61  jetted from the throat  4  in order to cancel outward momentum of the particles. 
     Further, when the throat vanes  40  are shaped into rectangles, manufacturing can be made easy. As shown in  FIG. 8 , therefore, each throat vane  40  has a top end surface  40   a  inclined to be higher on its outer side. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent No. 4759285 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The throat  4  is abraded gradually with age due to collision with pulverized solid particles. Particularly the throat vanes  40  are abraded most severely. When the abrasion amount of the throat vanes  40  reaches a predetermined value, the throat  4  must be replaced by a new one. 
     A work schedule of several weeks is required to replace the throat  4  in a large-sized vertical pulverizing apparatus used in a coal fired boiler plant. The vertical pulverizing apparatus cannot be operated during that time, causing a hindrance to the operation of the boiler plant. For this reason, there is a request to make the abrasion resistant life of the throat  4  as long as possible, to thereby reduce the replacement frequency of the throat  4 . 
     On the other hand, as a result of fluid flow experiments or numerical analysis on the vertical pulverizing apparatus, it has been proved that the throat vanes  40  in the background-art vertical pulverizing apparatus are abraded severely for the following reason. 
     As shown in  FIG. 8 , the particles  68  falling down along the inner peripheral wall surface of the housing  32  slide down on the top surface of the slope part  43 . The particles  68  which have reached the top end surface  40   a  of each throat vane  40  have a diagonally downward velocity component. Therefore, the particles  68  temporarily enter the annular flow channel between the throat inner peripheral wall  41  and the throat outer peripheral wall  42 . When the particles  68  are blown upward by the primary air  61  flowing in the annular flow channel, a part of the particles  68  collide with the throat vanes  40 , causing abrasion of the throat vanes  40 , as shown in  FIG. 9 . 
     In addition, due to the downward velocity component of the particles  68  arriving at the top end surface  40   a  of each throat vane  40 , lumps with a large particle size enter more deeply into the annular flow channel. Accordingly, there also arises another problem that the large coal lumps may fall down into a wind box  31  under the throat vanes  40  easily, in addition to the abrasion of the throat vanes  40 . Further, incidental equipment for treating the falling lumps is required to increase the manufacturing cost of the vertical pulverizing apparatus. 
     The present invention has been developed in consideration of such actual circumferences inherent in the background art. An object of the invention, is to provide a vertical pulverizing apparatus capable of suppressing abrasion of throat vanes and elongating their abrasion resistant lives to thereby increase working efficiency. 
     Solution to Problem 
     In order to attain the foregoing object, the present invention is aimed at a vertical pulverizing apparatus including: a housing; a pulverizing table which is placed rotatably inside the housing; a pulverizer such as a pulverizing roller, which is disposed on the pulverizing table; a throat which is disposed between the housing and the pulverizing table; a wind box which is placed under the throat; and a conveying gas feeding unit such as a primary air duct, which feeds pulverized particle conveying gas such as primary air to the wind box, the throat having an annular flow channel which is surrounded by a throat inner peripheral wall and a throat outer peripheral wall and which is configured to be partitioned by a large number of throat vanes circumferentially at predetermined intervals so that a solid raw material such as coal can be pulverized to produce pulverized particles by meshing of the pulverizing table with the pulverizer, and the conveying gas fed from the conveying gas feeding unit to the wind box can be jetted to an outer peripheral part of the pulverizing table through the throat so as to convey the pulverized particles to above the pulverizing table. 
     Provided is a first means of the invention, wherein: a slope part extending diagonally downward from an inner peripheral wall surface of the housing toward a top end of the throat outer peripheral wall and a horizontal part extending from a bottom end of the slope part continuously to the top end of the throat outer peripheral wall are provided all over the circumference between the housing and the throat; and 
     top end surfaces of the throat vanes and a top surface of the horizontal part are set at the same height. 
     According to a second means of the invention, there is provided the first means, wherein: 
     the top end surface of each of the throat vanes is formed into a horizontal surface. 
     According to a third means of the invention, there is provided the first or second means, wherein: 
     the slope part, the horizontal part and the throat are formed into an integral structure, and the integral structure is attached to the outer peripheral part of the pulverizing table so as to rotate together with the pulverizing table; and 
     a gap is formed between the housing and the slope part so that a part of the conveying gas can be jetted to above the pulverizing table through the gap. 
     According to a fourth means of the invention, there is provided the first or second means, wherein: 
     the slope part is divided into an inside slope part and an outside slope part disposed on the radially outer side of the inside slope part, and the inside slope part, the horizontal part and the throat are attached to the outer peripheral part of the pulverizing table so as to rotate together with the pulverizing table while the outside slope part is attached to the inner peripheral wall surface of the housing; and 
     a gap is formed between the inside slope part and the outside slope part so that a part of the conveying gas can be jetted to above the pulverizing table through the gap. 
     According to a fifth means of the invention, there is provided the fourth means, wherein:
         a slope angle of the inside slope part is substantially equal to a slope angle of the outside slope part.       

     According to a sixth means of the invention, there is provided the first or second means, wherein: 
     the slope part, the horizontal part and the throat outer peripheral wall are formed into an integral structure, and the integral structure is attached to the inner peripheral wall surface of the housing; 
     the throat inner peripheral wall and the throat vanes are attached to the outer peripheral part of the pulverizing table so as to rotate together with the pulverizing table; and 
     a gap between the throat outer peripheral wall and each of the throat vanes is formed inside the annular flow channel between the throat inner peripheral wall and the throat outer peripheral wall. 
     According to a seventh means of the invention, there is provided the first or second means, wherein: 
     the slope part, the horizontal part and the throat are formed into an integral structure, and the integral structure is attached to the inner peripheral surface of the housing; and 
     a gap is formed between the throat and the pulverizing table. 
     Advantageous Effects of Invention 
     According to the present invention configured as described above, it is possible to provide a vertical pulverizing apparatus capable of suppressing abrasion of throat vanes and elongating their abrasion resistant lives to thereby increase working efficiency. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  A sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a first embodiment of the invention. 
         FIG. 2  A sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a second embodiment of the invention. 
         FIG. 3  A sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a third embodiment of the invention. 
         FIG. 4  A sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a fourth embodiment of the invention. 
         FIG. 5  An enlarged development view of a throat vane according to a comparative example. 
         FIG. 6  An enlarged development view of a throat vane according to an embodiment of the invention. 
         FIG. 7  A schematic configuration view of a background-art vertical pulverizing apparatus. 
         FIG. 8  A sectional view of the vicinities of a throat portion of the background-art vertical pulverizing apparatus. 
         FIG. 9  A development view of a throat of the background-art vertical pulverizing apparatus. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the invention will be described below with reference to the drawings. 
     First Embodiment 
       FIG. 1  is a sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a first embodiment of the invention. The overall configuration, functions, etc. of the vertical pulverizing apparatus are similar to those in the vertical pulverizing apparatus shown in  FIG. 7 , and their description will be omitted. 
     As shown in  FIG. 1 , a throat  4  is an annular flow channel surrounded by a throat inner peripheral wall  41  and a throat outer peripheral wall  42 . In addition, a large number of throat vanes  40  each inclined at a desired angle α with respect to a rotation direction X of a pulverizing table  2  are placed at intervals in the circumferential direction of the throat  4  so that a turning force can be given to primary air  61  jetted from the throat  4 . 
     In the embodiment, as shown in  FIG. 1 , the throat  4  is a rotary type throat which is attached to the pulverizing table  2  so as to rotate together with the pulverizing table  2 . 
     An inside slope part  43   a  which is fixed to the throat  4  so as to rotate together with the throat  4  and an outside slope part  43   b  which is fixed to a housing  32  so as not to rotate are placed between the top end of the throat outer peripheral wall  42  (that is, the outer peripheral edge of a top end surface  40   a  of each throat vane  40 ) and the housing  32 . The slope surface of the inside slope part  43   a  and the slope surface of the outside slope part  43   b  are substantially on the same plane, and a slope part  43  is constituted by the inside slope part  43   a  and the outside slope part  43   b.    
     A gap  45  is formed between the inside slope part  43   a  and the outside slope part  43   b . This gap  45  will be described later. 
     In addition, a horizontal part  44  whose planar shape is annular is provided between the outer peripheral edge of the top end surface  40   a  of each throat vane  40  and the inner peripheral edge of the inside slope part  43   a.    
     Particles  68  falling down along the inner peripheral wall of the housing  32  slide down on the slope surface extending from the outside slope part  43   b  to the inside slope part  43   a . On arriving at the horizontal part  44 , the particles  68  change their moving direction from a diagonally downward direction to a lateral direction. That is, when the particles  68  arrive at the top end surface  40   a  of each throat vane  40 , a downward velocity component disappears. 
     Therefore, there is no fear that the particles  68  may enter into the annular flow channel between the throat inner peripheral wall  41  and the throat outer peripheral wall  42 , but the particles  68  are blown upward by the primary air  61  jetted from the annular flow channel. As a result, the particles  68  hardly collide with the throat vanes  40  so that abrasion of the throat vanes  40  can be suppressed. In addition, lumps with a large particle size hardly enter into the annular flow channel. Accordingly, the problem that the large lumps may flow down into a window box  31  located under the throat vanes  40  can be also solved. 
     In the embodiment, the slope part  43  is divided into the inside slope part  43   a  and the outside slope part  43   b . This configuration has two advantages as follows. 
     (1) It is easy to adjust the gap  45  between the inside slope part  43   a  and the outside slope part  43   b . When the gap  45  is too wide, the amount of the primary air  61  leaking out through the gap  45  increases to cause reduction of the flow rate of the primary air  61  flowing in the annular flow channel between the throat inner peripheral wall  41  and the throat outer peripheral wall  42 . Thus, the velocity of the air flow is lowered. As a result, the particles  68  fall down into the annular flow channel easily. To suppress this, the gap  45  is adjusted to be several mm. 
     The outer diameter of the inside slope part  43   a  which can rotate has very high roundness due to machining or the like. However, in a vertical pulverizing apparatus for use in a coal fired boiler plant, the housing  32  is a huge cylinder whose diameter is 4 to 5 meters, and the inner diameter of the housing  32  has a circumferential distortion (deviation from a true circle) of about ten-odd mm. 
     Then, high roundness can be set in the inner diameter of the outside slope part  43   b , for example, by adjustment of the attachment position of the outside slope part  43   b  or machining of the outside slope part  43   b . Thus, the gap  45  between the inside slope part  43   a  and the outside slope part  43   b  can be adjusted to be about several mm easily. 
     (2) A part of the particles  63  which are falling down can be blown to above the pulverizing table  2  by the primary air  61  jetted upward from the gap  45 . It has been confirmed by flow analysis or the like that, in spite of the gap  45  about several mm wide, the flow velocity of the primary air  61  jetted therefrom becomes substantially equal to the flow velocity of the primary air  61  flowing in the annular flow channel, and the flow velocity reaches several tens m/s. 
     In this manner, a part of the particles  68  sliding down on the slope part  43   b  are blown away so that the amount of the particles  68  arriving at the top end surface  40   a  of each throat vane  40  can be reduced. 
     It is desirable that the slope angle of the inside slope part  43   a  is substantially equal to the slope angle of the outside slope part  43   b . However, a difference in slope angle between the both can be allowed if the slope angles are not smaller than the repose angle of the particles  68  sliding down. For example, a difference in slope angle may be provided between the outside slope part  43   b  whose slope angle is increased and the inside slope part  43   a  whose slope angle is decreased. 
       FIG. 5  is an enlarged development view of a throat vane according to a comparative example. A stagnant part  65  where a flow velocity is locally slow is formed near the top end surface  40   a  of each throat vane  40 . As shown in  FIG. 5 , when the top end surface  40   a  of the throat vane  40  is lower than a top end  42   a  of the throat outer peripheral wall  42  and the horizontal part  44 , a part of the particles  68  supplied from the horizontal part  44  fall down to the top end surface  40   a  of the throat vane  40  and enter into the annular flow channel. The part of the particles  68  supplied from the horizontal part  44  fall down in the stagnant part  65 . That is, when the particles  68  arrive at the top end surface  40   a  of the throat vane  40 , the particles  68  have a downward velocity component again. Thus, the particles  68  enter into the annular flow channel easily. 
     When the particles  6  are blown by the primary air  61  flowing in the annular flow channel, the particles  68  collide with the throat inner peripheral wall  41  or the throat outer peripheral wall  42 , causing abrasion in that part. 
       FIG. 6  is an enlarged development view of a throat vane according to an embodiment of the invention. In the embodiment, as shown in  FIG. 6 , the top end surface  40   a  of each throat vane  40 , the top end  42   a  of the throat outer peripheral wall  42  and the top surface of the horizontal part  44  are set at the same height in order to prevent abrasion in the throat inner peripheral wall  41  or the throat outer peripheral wall  4 . 
     In addition, in the embodiment, as shown in  FIG. 6 , the top end surface  40   a  of the throat vane  40  is formed into a horizontal surface. In the background-art vertical pulverizing apparatus, as shown in  FIG. 8 , the top end surface  40   a  of the throat vane  40  is inclined to be higher on the outer side, and the throat vane  40  has a shape in which the throat vane  40  protrudes more upward on the outer side than on the inner side. Thus, the throat vane  40  is abraded easily on the outer side to thereby shorten the useful life of the throat vane  40 . To solve this problem, the top end surface  40   a  of the throat vane  40  is formed into a horizontal surface in the embodiment. 
     It is desirable that the radial width (length) of the horizontal part  44  is at least 10 mm in consideration of the size of particles (coal particles in the embodiment) circulating inside the vertical pulverizing apparatus and the necessity to change the moving direction of the particles  68  falling down along the slope part  43  to a lateral direction. 
     Second Embodiment 
       FIG. 2  is a sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a second embodiment of the invention. 
     This embodiment is different from the first embodiment shown in  FIG. 1  at the point that the slope part  43  is not divided into two, but the slope part  43  consisting of one member is attached to the pulverizing table  2 , and the gap  45  is formed between the slope part  43  and the housing  32 . A part of particles  68  falling down can be blown upward by the primary air  61  jetted upward from the gap  45 . Thus, the amount of particles  68  arriving at the too end surface  40   a  of each throat vane  40  can be reduced. 
     This embodiment has such an advantage that the slope part  43   b  fixed to the housing  32  can be eliminated so that the number of parts can be reduced and assembling can be made easy, as compared with the first embodiment. 
     Third Embodiment 
       FIG. 3  is a sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a third embodiment of the invention. 
     In this embodiment, an integral structure  46  in which the slope part  43 , the horizontal part  44  and the throat outer peripheral wall  42  are formed integrally is fixed to the housing  32 . On the other hand, the throat inner peripheral wall  41  and the throat vanes  40  are fixed to the pulverizing table  2 . Accordingly, as shown in  FIG. 3 , the gap  45  is formed in the annular flow channel between the throat inner peripheral wall  41  which is rotating and the throat outer peripheral wall  42  which is fixed. The gap  45  becomes a part of the annular flow channel. 
     According to this configuration, the flow rate of the primary air  61  flowing in the annular flow channel remains the same even when the gap  45  is widened. There fore, there is an advantage that the size of the gap  45  can be increased. 
     Fourth Embodiment 
       FIG. 4  is a sectional view of the vicinities of a throat portion of a vertical pulverizing apparatus according to a fourth embodiment of the invention. 
     An integral structure  47  in which the slope part  43 , the horizontal part  44 , the throat outer peripheral wall  42 , the throat inner peripheral wall  41  and the throat vanes  40  are formed integrally serves as a fixed type throat which is fixed to the housing  32 . Accordingly, the gap  45  is formed between the pulverizing table  2  and the throat inner peripheral wall  41 . 
     In spite of such a fixed type throat, the horizontal part  44  can be provided between the top end of the throat outer peripheral wall  42  (that is, the outer edge of the top end surface  40   a  of each throat vane  40 ) and the slope part  43  as shown in  FIG. 4 . 
     According to each of the embodiments of the invention, abrasion of the throat can be suppressed so that the abrasion resistant life of the throat can be elongated. As a result, the replacement frequency of the throat can be reduced so that a vertical pulverizing apparatus with high working efficiency can be provided. In addition, when the abrasion resistant life is elongated, the maintenance cost of the vertical pulverizing apparatus can be reduced. 
     Further, according to the invention, the problem that large lumps may fall down into the primary air wind box under the throat can be also solved. Therefore, incidental equipment for treating the falling lumps can be dispensed with. Thus, the manufacturing cost of the vertical pulverizing apparatus can be reduced. 
     Although a vertical pulverizing apparatus for pulverizing coal has been described in each of the embodiments the invention is not limited thereto. For example, the invention is also applicable to a vertical pulverizing apparatus for pulverizing another kind of solid matter such as biosolid including woody chips or the like, cement, etc. 
     Although pulverizing rollers are used for pulverizing solid matter in the embodiments, the invention is not limited thereto. For example, the invention is also applicable to a vertical pulverizing apparatus using another pulverizer such as a pulverizing ball. 
     REFERENCE SIGNS LIST 
     
         
         
           
               2 : pulverizing table 
               3 : pulverizing roller 
               4 : throat 
               30 : primary air duct 
               31 : primary air wind box 
               32 : housing 
               40 : throat vane 
               40   a : top end surface of throat vane 
               41 : throat inner peripheral wall 
               42 : throat outer peripheral wall 
               43 : slope part 
               43   a : inside slope part 
               43   b : outside slope part 
               44  horizontal part 
               45 : gap 
               46 ,  47 : integral structure 
               61 : primary air 
               62 : group of particles 
               65 : stagnant part 
             B: pulverization portion 
             C: classification portion

Technology Classification (CPC): 5