Gasification of carbonaceous material

Abstract

A grate assembly ( 10 ) for a gasifier for gasifying carbonaceous material producing ash includes an upper rotatable grate component ( 11 ) and a lower rotatable support structure ( 12 ) fastened to the upper rotatable grate component ( 11 ) by a plurality of removable fasteners ( 15 ) acting to prevent vertical displacement of the upper rotatable grate component ( 11 ) and the lower rotatable support structure ( 12 ). The lower rotatable support structure ( 12 ) is configured to be drivingly rotated about a common vertical axis of rotation ( 21 ) shared with the upper rotatable grate component ( 11 ). The assembly ( 1 ) further includes at least two key torque transmitters ( 16 ) spaced angularly relative to the common axis of rotation ( 21 ) and engaging the upper rotatable grate component ( 11 ) and the lower rotatable support structure ( 12 ) to transfer torque from the lower rotatable support structure ( 12 ) to the upper rotatable grate component ( 11 ) when the lower rotatable support structure ( 12 ) is driven.

1 . A grate assembly for a gasifier for gasifying carbonaceous material producing ash, the grate assembly including:
 an upper rotatable grate component; and   a lower rotatable support structure fastened to the upper rotatable grate component by a plurality of removable fasteners acting to prevent vertical displacement of the upper rotatable grate component and the lower rotatable support structure, the lower rotatable support structure being configured to be drivingly rotated about a common vertical axis of rotation shared with the upper rotatable grate component,   the assembly further including at least two key torque transmitters spaced angularly relative to said common axis of rotation and engaging the upper rotatable grate component and the lower rotatable support structure to transfer torque from the lower rotatable support structure to the upper rotatable grate component when the lower rotatable support structure is driven.   
     
     
         2 . The grate assembly of  claim 1 , wherein the key torque transmitters are equiangularly spaced in a horizontal plane about the common vertical axis of rotation. 
     
     
         3 . The grate assembly of  claim 1  or  claim 2 , wherein two key torque transmitters are provided and are spaced 170-190° apart. 
     
     
         4 . The grate assembly of  claim 1  or  claim 2 , wherein three key torque transmitters are provided and are spaced 110-130° apart. 
     
     
         5 . The grate assembly of  claim 1  or  claim 2 , wherein the key torque transmitters are arranged in sets of two, with the two key torque transmitters in a set being positioned in diametrically opposed positions about the common vertical axis of rotation. 
     
     
         6 . The grate assembly of any of  claims 1  to  5 , wherein the key torque transmitters are arranged in a circle and are interspaced by at least one fastener between adjacent key torque transmitters, the fastener acting to inhibit or prevent vertical displacement of the upper rotatable grate component and the lower rotatable support structure. 
     
     
         7 . The grate assembly of  claim 6 , wherein the fasteners are in the form of nut and bolt arrangements. 
     
     
         8 . The grate assembly of any of  claims 1  to  7 , wherein the key torque transmitters are unthreaded and do not act to inhibit or prevent vertical displacement of the upper rotatable grate component and the lower rotatable support structure. 
     
     
         9 . The grate assembly of  claim 8 , wherein the key torque transmitters are tapered from a wider operatively upper end to a narrower operatively lower end. 
     
     
         10 . The grate assembly of  claim 1 , wherein the key torque transmitters are elongate and polygonal in outline in end view. 
     
     
         11 . A gasifier for gasifying carbonaceous material, the gasifier including a grate assembly as claimed in any of  claims 1  to  10  mounted within a gasification chamber defined by a gasification vessel with the lower rotatable support structure of the grate assembly being connected to drive means. 
     
     
         12 . The gasifier of  claim 11 , which is a fixed bed gasifier 
     
     
         13 . The gasifier of  claim 11  or  claim 12 , which is a fixed bed dry bottom gasifier. 
     
     
         14 . The gasifier of  claim 13 , which is a coal, waste or biomass gasifier, or a gasifier configured to gasify a combination of two or more of coal, waste and biomass. 
     
     
         15 . The gasifier of  claim 14 , which is a coal gasifier operating at an elevated pressure of between 5 bar(g) and 100 bar(g) and a temperature of between 400° C. and 1600° C.