Plate-formed grate element for a movable grate of a furnace

A plate-formed grate element for a movable grate of a furnace,

• the movable grate including a number of pivotal grate shafts carrying plate-formed grate elements and thereby defining an inclined grate surface, the movable grate including a drive mechanism being arranged for pivoting back and forth neighbouring grate shafts in opposite rotational directions so as to impart a wave-like movement to material on the grate surface in order to transport such material downwards, and the movable grate including a synchronising mechanism being arranged to maintain a predetermined clearance between edge portions of plate-formed grate elements of neighbouring grate shafts during the pivoting movement of the grate shafts,
• the plate-formed grate element having a top wall, a bottom wall, a front end and a back end,
• the front end of the plate-formed grate element having a lower inwardly curved wall portion being adapted to maintain said predetermined clearance with a back tip edge of the back end of an adjacent plate-formed grate element during part of said pivoting movement of the grate shafts when said plate-formed grate elements are arranged on neighbouring grate shafts, and
• the plate-formed grate element being provided with an internal cooling fluid chamber including an internal front cooling fluid channel having an inlet end and an outlet end and extending along the front end of the plate-formed grate element and above at least a part of the lower inwardly curved wall portion of the front end,
• wherein the plate-formed grate element has an outwardly curved front wall extending from the top wall of the plate-formed grate element to the lower inwardly curved wall portion of the front end, wherein a front tip edge of the front end is formed by the outwardly curved front wall at its connection with the lower inwardly curved wall portion, and
• wherein the outwardly curved front wall has a nominal wall thickness varying by less than ±35 percent,
• wherein the part of the outwardly curved front wall extending from the top wall of the plate-formed grate element to the front tip edge has an outer contour with a first nominal radius of curvature (R) varying by less than ±40 percent,
• wherein the front tip edge has an outer contour with a second nominal radius of curvature (r) varying by less than ±20 percent, and
• wherein the first nominal radius of curvature (R) is more than 2 times larger than the second nominal radius of curvature (r).