Abstract:
The invention relates to a stoker grates for circulating burning-up, wherein the existing reciprocal-type or chain-type grates are designed to be a long annular-shape with front and rear ends closed, resulting in burning-up of coal and thus overcoming the following defects of the existing coal-firing stokers: the coal remains on the grate shortly and can not be completely burn up, causing a waste of coal and low combustion efficiency.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a boiler stoker, specially, to the grate of horizontal circulating burning-up.  
       DESCRIPTION OF THE PRIOR ART  
       [0002]     At present the grates for stoker-fired boiler can be classified in structure into two kinds, i.e. the reciprocating grate and the chain grate. The fuel is fed continuously to one end of the grate surface and travels horizontally across the grate as it burns. The residual ash is discharged from the opposite end. The above mentioned stoker grates have the following defects: 1) the coal is ignited mainly by means of the heat radiation from the furnace arch, the ignition begins from the upper layer towards the lower layer of the coal bed in a direction which is opposite to the direction of air flow, resulting in an unfavorable burning state and cause incomplete combustion; 2) the resident time of coal burning on the grate can not be long as the grate has a limited length, so the coal can not be fully burn up; and 3) the bottom layer of the coal is ignited at last, resulting in the fine coal particles to leak out from the vent slits of the grate and cause a big loss of coal.  
       SUMMARY OF THE INVENTION  
       [0003]     An object of the present invention is to provide a boiler stoker for horizontal circulating burning-up, which overcome the following defects of the reciprocating and chain grates used for the existing coal-fired stokers: the resident time of coal burning on the grate is insufficient, the ignition of coal mainly by means of the heat radiation from the furnace, so the coal can not be fully burn up, and the fine coal particles in the bottom layer is easy to leak out from the vent slits of the grate and lead to a remarkable coal loss.  
         [0004]     In order to achieve the object of this invention, the technical scheme is as follows: Let the both ends of the conventional stoker grate connect together and make an enclosed long annular moving grate. The coal is burn on the long annular grate with a pattern of horizontal circulating burning.  
         [0005]     The first aspect of the invention comprises a stationary grate sheets support, moveable grate sheets supports fitting with prop rolls on the stationary grate sheets support, stationary grate sheets fitting with mounting transverse beams of the stationary grate sheets support, moveable grate sheets fitting with mounting transverse beams of the moveable grate sheets supports and a driving unit, wherein the moveable grate sheets and the stationary grate sheets are placed alternatively, the mentioned stationary grate sheets support has a long annular shape, the mentioned moveable sheet supports comprise a pair of rectangular supports opposed to each other and another pair of annular-shaped moveable grate sheet supports opposed to each other so as to form a long annular-shaped assembled support, the mentioned driving unit is a set of bearing units which are mounted on the stationary grate sheet support, oscillating rods are connected between the bearings of said bearing units, and at least one of the rectangular moveable grate sheet supports and the arc-shaped moveable furnace grate sheet supports in said moveable grate sheet supports, the arc-shaped or rectangular moveable grate sheet support connected with said oscillating rods is a driving moveable grate sheet support, the arc-shaped or rectangular moveable grate sheet support not connected with said oscillating rods is a driven moveable grate sheet support, the adjacent driving moveable grate sheet support is hinged to the driven moveable grate sheet support and the driven moveable grate sheet supports are hinged, and one of said oscillating rods is connected with a power input link.  
         [0006]     The second aspect of the invention comprises a stationary grate sheet support, moveable grate sheet supports fitting with prop rolls on the stationary grate sheet support, stationary grate sheets fitting with mounting transverse beams of the stationary grate sheet support, and moveable grate sheets fitting with mounting transverse beams of the moveable grate sheet supports, wherein the moveable grate sheets and the stationary grate sheets are placed alternatively, said stationary grate sheet support has a long annular shape, said moveable grate sheet supports comprise a pair of rectangular moveable grate sheet supports opposed to each other and another pair of arc-shaped moveable grate sheet supports opposed to each other so as to form a long annular shape assembled support, said rectangular moveable grate sheet supports is hinged with the arc-shaped moveable grate sheet supports, and one of the said rectangular moveable grate sheet support or arc-shaped moveable grate sheet support is connected with a power input link.  
         [0007]     The third aspect of the invention comprises a stationary grate sheet support, moveable grate sheet supports fitting with prop rolls on the stationary grate sheet support, stationary grate sheets fitting with mounting transverse beams of the stationary grate sheet support, moveable grate sheets fitting with mounting transverse beams of the moveable grate sheet supports, and a transmission unit, wherein the moveable grate sheets and the stationary grate sheets are placed alternatively, both the said stationary grate sheet support and moveable grate sheet supports have a long annular shape, the said transmission unit is a bearing unit which is located at the center of said moveable grate sheet supports and fixed to said stationary grate sheet support, an oscillating rod is connected between the bearing of said bearing unit and said moveable grate sheet supports, and said oscillating rod is connected with a power input link.  
         [0008]     The fourth aspect of the invention comprises a grate support, a chain and a transmission unit, wherein the chain comprises a driving grate sheet chain and a driven grate sheets, the said driving grate sheet chain has a horizontal annular shape structure, the driven grate sheets are inserted in two opposed directions alternatively and fixed with the pin shafts of the driving grate sheet chain, the sides of the adjacent driven furnace grate sheets are overlapped or connected with each other, and there are one or more ash discharge exits on the side wall of the grate support.  
         [0009]     The invention, as compared with the existing art, has the following features: the grate has a long annular shape structure, the coal can be circulated and burned on the grate, the resident time of coal burning on the grate can be much longer, the bottom burning coal layer forms a sufficient ignition heat source, the new feeding coal covers on the circulating burning coal layer, the combustion begins from the lower layer towards upper layer and keeps the same direction as that of the air flow, so as to form a complete combustion state. The invention has the following benefit effects: 1) the coal can be totally burning up and combustion efficiency can be remarkably improved, (increased by more than 11% as compared to the conventional coal-firing stoker); 2) the blackness and the dust emission in the flue gas can be much lower; 3) combustion can be performed at low temperature (900° C.), desulphurization and the lower concentration of harmful NOx in the flue gas are achieved, and the effect can be corresponding to that of the circulating fluidized-bed furnace; 4) the coal of low heating value (as low as 12.56 MJ/kg) can be burnt; and 5) the comprehensive operation cost is only a half of that of a circulating fluidized-bed furnace. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a schematic plan view of a stoker grate for circulating burning-up in the case that the said moveable grate sheet supports are long annular shape assembled supports and the said transmission unit is two sets of bearing units;  
         [0011]      FIG. 2  is an enlarged structure schematic view of a stoker grate for circulating burning-up taken along A-A in  FIG. 1 . In the case that said moveable grate sheet supports are long annular shape assembled supports and said transmission unit is two sets of bearing units;  
         [0012]      FIG. 3  is a structure schematic view of a stoker grate for circulating burning-up in the case that the said moveable grate sheet supports are long annular shape assembled supports and the said transmission unit is one set of bearing unit located at the center of the stationary grate sheet support;  
         [0013]      FIG. 4  is a structure schematic plan view of a stoker grate for circulating burning-up in the case that the said moveable grate sheet supports are long annular shape assembled supports and the said transmission unit is one set of bearing unit located on outside of the stationary grate sheet support;  
         [0014]      FIG. 5  is a structural top view of a stoker grate for circulating burning-up in the case that there is no said bearing unit;  
         [0015]      FIG. 6  is a structure schematic view of a stoker grate for circulating burning-up in the case that both stationary grate sheet support and moveable grate sheet supports have a annular shape; and  
         [0016]      FIG. 7  is a schematic view of a stoker grate for circulating burning-up in the case that it is consisted of a chain structure. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     Hereinafter, the preferred embodiments of the invention will be described with reference to the drawings. In an embodiment shown as in  FIGS. 1 and 2 , the grate comprises a stationary grate sheet support  1 , moveable grate sheet supports fitting with prop rolls  2  on the stationary grate sheet support  1 , the stationary grate sheets  4  fitting with mounting transverse beams  3  of the stationary grate sheet support  1 , moveable grate sheets  6  fitting with mounting transverse beams  5  of the moveable grate sheet support, and a transmission unit, wherein the moveable grate sheets  6  and the stationary grate sheets  4  are disposed alternatively, the stationary grate sheet support  1  has a long annular shape, the moveable grate sheet supports comprise a pair of rectangular moveable grate sheet supports  7  opposed to each other and another pair of semi-annular moveable grate sheet supports  8  opposed to each other to form a long annular shape assembled support, the transmission unit is two sets of bearing units  9  and  10 , which are fixed to the stationary grate sheet support  1 , and which are located at the centers of the semi-annular moveable grate sheet supports  8 , respectively, oscillating rods  11  are connected respectively between the bearings of the bearing units  9  and  10 , and respective semi-annular moveable grate sheet support  8 , and between rectangular moveable grate sheet supports  7 . One of the oscillating rods  11  is connected with a power input link  12 . Between the stationary grate sheets  4  and the moveable grate sheets  6  in the burning-up zone there are ash falling slits  13  of 15-20 mm, under which there is a ash discharge opening  14 . In an embodiment shown as in  FIG. 3 , a transmission unit is a set of bearing unit  9  which is located at the center of said stationary grate sheet support  1 , an oscillating rod  11  is connected between the bearing of the bearing unit  9  and the middle portion of the rectangular moveable grate sheet supports  7 , roller seats each with a limit roller  15  are bolt-fixed onto the inner walls on two sides of the moveable grate sheets  6  on the semi-annular moveable grate sheet supports  8  corresponding stationary grate sheet support  1 , and hinges  16  are connected between the rectangular moveable grate sheet supports  7  and the semi-annular moveable grate sheet supports  8 . In an embodiment shown as in  FIG. 4 , a transmission unit is a set of bearing unit  9  which is located the outside of the stationary grate sheet support  1 , an oscillating rod  11  is connected between the bearing of the bearing unit  9  and one of the semi-annular moveable grate sheet supports  8  in the moveable grate sheet supports, and roller seats each with a limit roller  15  are bolt-fixed onto the inner walls on two sides of the moveable grate sheets  6  on the semi-annular moveable grate sheet supports  8  of stationary grate sheet support  1 . In an embodiment without said bearing unit shown as in  FIG. 5 , one of said rectangular moveable grate sheet supports  7  or semi-annular shape moveable grate sheet supports  8  is connected with a power input link  12 , and limit rollers  23  are fixed onto the inner walls on outside plate at the semi-annular moveable grate sheet supports  8  of stationary grate sheet support  1 . In an embodiment shown as in  FIG. 6 , a grate comprises a stationary grate sheet support  1 , a moveable grate sheet support fitting with prop rolls  2  on the stationary grate sheet support  1 , stationary grate sheets  4  fitting with mounting transverse beams of the stationary grate sheet support  1 , moveable grate sheets  6  fitting with mounting transverse beams of the moveable grate sheet support, and a transmission unit, wherein the moveable grate sheets  6  and the stationary grate sheets  4  are disposed alternatively, both the stationary grate sheet support  1  and the moveable grate sheet support are annular in shape, the transmission unit is a bearing unit  9  which is fixed to the stationary grate sheet support  1 , and which are located at the center of the annular of the moveable grate sheet support, respectively, oscillating rods  11  are connected between the bearing of the bearing unit  9  and the moveable grate sheet support, one of the oscillating rods  11  is connected with a power input link  12 . Between the stationary grate sheets  4  and between the moveable grate sheets  6  there are ash falling slits  13  of 15-20 mm above a ash discharge opening  14  correspondingly. In an embodiment shown as in  FIG. 7 , a grate comprises a grate support  17 , a chain and a transmission unit, wherein the chain comprises a driving grate sheet chain  18  and a driven grate sheets  19 , the driving grate sheet chain  18  has a horizontal long annular shape structure, the driven grate sheets  19  are inserted in two opposed directions alternatively and fixed with the pin shafts  20  of the driving grate sheet chain  18 , the adjacent driven grate sheets  19  are overlapped or connected with each other, and on a side wall of the grate sheet support  17  there is a ash discharge exit  21 . When the embodiments shown in  FIGS. 1-6  are been carried out, the link  12  is connected with a driver  22 . When the embodiment shown in  FIG. 7  is been carried out, a driving chain pulley shaft  24  is connected with a power input device.