Method and apparatus for burning solid fuel
OwnerViking V. Demarinventor
Life of this patent
Estimating the term…
Abstract
Solid fuel such as coal is fed into an inlet shaft of the furnace through a rotary feeder constructed to prevent the admission of air. Primary air channels supply the major part of the air required for combustion of the fuel in a region in which the fuel bed is sufficiently thick to avoid disturbance and the formation of "holes" by this air. Further, narrower air channels supply sufficient, diffused and low velocity air to complete the combustion of the fuel without substantial entrainment of grit and ash. Air is prevented from flowing in contact with the fuel up stream of the primary channels and the metering edge.
Claims23
A high intensity method of burning solid fuel in pieces, comprising the steps of:
- advancing the fuel along a path having an upstream portion from which air is excluded;
- metering the height of the fuel leaving the upstream path portion to define a predetermined cross section for the fuel as it leaves the upstream path portion and enters a first downstream path portion in a reverberatory combustion space as a thick fuel bed;
- passing a first high velocity stream of air from below the first downstream path portion upwardly through the fuel bed in a self-sustaining ignition zone, the first stream of air supplying the major portion of the oxygen required for combustion and having upstream and downstream boundaries extending transversely of the path, the fuel being rapidly heated and ignited as it moves through the upstream boundary, the metered height of the fuel fed being such in relation to the speed of advance of the fuel and the distance between the upstream and downstream boundaries that the size of the fuel pieces and the thickness of the burning fuel bed at the downstream boundary is still sufficient to prevent destabilization of the fuel bed by the first stream;
- and
- passing a second, lower velocity stream of air, sufficient to complete combustion, through the fuel bed at a second downstream path portion which is downstream of the first downstream path portion, the second stream being diffused over a sufficient length of the path downstream of the first stream so as to be of sufficiently low velocity to avoid entrainment of the burning-out fuel particles from the fuel bed.
A furnace for burning solid fuel in pieces comprising means defining a reverberatory combustion chamber having a metering opening, a reciprocatory grate comprising longitudinally reciprocatory grate bars projecting into the combustion chamber for advancing solid fuel along the grate through the metering opening into the combustion chamber, means for supplying solid fuel to fill the entry to the metering opening, means for preventing air from entering the solid fuel upstream of the metering opening, a first set of air channels through the grate for passing a high-velocity first stream of air up through the fuel bed on the grate downstream of the metering opening, said first channels being sized to pass substantially the whole of the air required for combustion separation means associated with said grate for defining upstream and downstream boundaries for the first stream, and a second set of air channels through the grate for passing a restricted second stream of diffused air up through the portion of the fuel bed on the grate downstream of the first channels to complete the combustion of the fuel, said furnace including wall means whereby substantially no air from any of the said channels is able to enter the fuel upstream of the metering opening.
Dependencies are inferred from the claim text.