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US 2018/0156453 A1Published application
Method and apparatus for the improved combustion of biomass fuels
OwnerDaniel R. Higgins, Eugene Sullivaninventors
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OwnerDaniel R. Higgins, Eugene Sullivaninventors
Estimating the term…
A cylindrical furnace having a vertical axis controls combustion. Solid fuel, particulates, and gases inside the furnace rotate around the axis, inducing radial stratification using centrifugal forces. Fuel and particulates drag on the wall of the cylinder, slipping in and out of suspension, thereby increasing particle residence times. The solid particles comprise combustible fuel particles, and non-combustible ash and contaminants. Control of the temperature of non-combustible particles and the wall surface prevents these non-combustible particles from adhering to, and building up on, the furnace wall. It is also advantageous to control the gas temperature leaving the furnace to minimize temperature-driven corrosion of downstream heat-exchange surfaces. Method and apparatuses are described to control the gas, non-combustible particle, and wall temperatures. The furnace can be integrated into a stand-alone boiler or as a combustor in which a portion of the pyrolysis gas from the combusting fuel is burned in a separate vessel.
A furnace burning biomass fuel defined by a cylindrical enclosure with a vertical axis, a top of said enclosure disposed to conduct hot gases to heat-absorbing surfaces or to a separate means for further combustion, in which solid fuel particles and combustion air are injected into said furnace and said fuel burns releasing gaseous products of combustion, in which noncombustible particles are present, in which said gases are induced to rotate around the vertical axis and said rotation entrains at least some of said fuel and noncombustible particles to rotate with said gases, and an average residence time of said particles in said cylindrical enclosure is greater than an average residence time of said gases in said cylindrical enclosure, and in which an air-to-fuel ratio is controlled at least at one combustion air injection elevation to control a temperature above the elevation of said combustion air injection.
A furnace burning biomass fuel defined by a cylindrical enclosure with a vertical axis, a bottom of said enclosure being conically shaped and truncated at a floor, a top of said enclosure disposed to conduct hot gases to heat-absorbing surfaces or to a separate means for further combustion, in which solid fuel particles and combustion air are injected into said furnace and said fuel burns releasing gaseous products of combustion, in which noncombustible particles are present, in which said gases are induced to rotate around the vertical axis and said rotation entrains at least some of said fuel and noncombustible particles to rotate with said gases, and tan average residence time of said particles in said cylindrical enclosure is greater than an average residence time of said gases in said cylindrical enclosure, and in which an air-to-fuel ratio is controlled at least at one combustion air injection location within said conically shaped bottom to control a temperature within said conically shaped bottom.
A furnace burning biomass fuel defined by a cylindrical enclosure with a vertical axis, a top of said enclosure disposed to conduct hot gases to heat-absorbing surfaces or to a separate means for further combustion, in which solid fuel particles and combustion air are injected into said furnace and said fuel burns releasing gaseous products of combustion, in which noncombustible particles are present, in which said gases are induced to rotate around the vertical axis and said rotation entrains at least some of said fuel and noncombustible particles to rotate with said gases, and an average residence time of said particles in said cylindrical enclosure is greater than an average residence time of said gases in said cylindrical enclosure, and in which a momentum of said injected combustion air and fuel is controlled, either together or separately, to control a rotation of said rotating gases.
A furnace burning biomass fuel defined by a cylindrical enclosure with a vertical axis, a top of said enclosure disposed to conduct hot gases to heat-absorbing surfaces or to a separate means for further combustion, in which solid fuel particles and combustion air are injected into said furnace and said fuel burns releasing gaseous products of combustion, in which noncombustible particles are present, in which said gases are induced to rotate about the axis of said cylindrical enclosure and said rotation entrains at least some of said fuel and noncombustible particles to rotate with said gases, and an average residence time of said particles in said cylindrical enclosure is greater than an average residence time of said gases in said cylindrical enclosure, and in which a rotational velocity of said rotating gases is measured at least at one location within said cylindrical enclosure, and in which said rotational velocity measurement is used as an input to a control loop to regulate said rotational velocity.
A furnace burning biomass fuel defined by a cylindrical enclosure with a vertical axis, a bottom of said enclosure conically shaped and truncated at a floor, a top of said enclosure disposed to conduct hot gases to heat-absorbing surfaces or to a separate means for further combustion, in which solid fuel particles and combustion air are injected into said furnace and said fuel burns releasing gaseous products of combustion, in which a portion of said injected fuel at least partially fills said bottom, in which noncombustible particles are present, in which said gases are induced to rotate around the vertical axis and said rotation entrains at least some of said fuel and noncombustible particles to rotate with said gases, and an average residence time of said particles in said cylindrical enclosure is greater than an average residence time of said gases in said cylindrical enclosure, in which said fuel residing in said bottom is induced to rotate about the vertical axis, and in which an injection of combustion air, furnace flue gas, or steam, is regulated to control a rotational velocity of said rotating fuel.
(canceled)
A method of operating a furnace, comprising:
Dependencies are inferred from the claim text.