Stoker backstop

Claim 2

In a solid-fuel burning furnace utilizing a moving grate stoker and having a fuel supply propelling solid fuel toward the rear of the moving grate of the stoker, including, a stoker grate having the configuration of an endless belt on supporting parallel and horizontal rollers, a fuel supply means mounted at the front end of the stoker to propel the solid fuel toward the rear end of the grate, a back furnace wall having parallel water tubes extending vertically over the grate and joined to each other by welding as a membrane, a first impact surface extending vertically downward from the furnace tubes over the rear portion of the grate, and a second impact surface extending at an angle to the horizontal beneath the first impact surface to engage the grate surface in completing a barrier to the solid fuel discharged toward the rear of the grate.

Claim 3

The structure of claim 1, in which, the two impact surfaces are provided structures mounted in suspension from the furnace tubes.

Claim 4

The combination of claim 2, in which, the impact surfaces are provided by keys having the configuration of keys forming the grate surface.

Claim 5

The combination of claim 1, including, pivot structure for the second impact surface arranged to enable the second impact surface to pivot in a vertical plane as the vertical distance between the furnace tubes and grate surface varies.

Claim 6

The pivot structure of claim 4, including, a stop structure to limit the clockwise pivoting range of the second impact surface when the furnace is out of service.

Claim 7

In a furnace having water-cooled walls as tube panels suspended over a moving grate on which a combusting bed is advanced from the rear of the furnace toward the front of the furnace a barrier structure, including, a first stationary section comprising a carrier bar fixed to the furnace tubes above the rear portion of the grate surface on which are mounted a row of grate keys which together form an impact surface facing the front of the furnace to shield the grate and furnace structure from the impact of non-combustible solid projectiles, a second section of the barrier comprising a carrier bar mounted to pivot from the furnace tubes above the grate on which keys are mounted to provide an impact surface extending from overlap with the impact surface of the first section down to the grate surface, and means for limiting the pivoting range of the second barrier section to prevent the lower end of the second section from destructive contact with the grate surface.

Claim 8

In a furnace having water-cooled walls as tube panels suspended over a moving grate on which a combusting bed is advanced from the rear of the furnace toward the front of the furnace a barrier structure, including, a first stationary section comprising a carrier bar fixed to the furnace tubes above the rear portion of the grate surface on which are mounted a row of grate keys which together form an impact surface facing the front of the furnace to shield the grate and furnace structure from the impact of non-combustible solid projectiles, a second section of the barrier comprising a carrier bar mounted to pivot from the furnace tubes above the grate on which keys are mounted to provide an impact surface extending from overlap with the impact surface of the first section down to the grate surface, and means for limiting the pivoting range of the second barrier section to prevent the lower end of the second section from destructive contact with the grate surface.