Fluid bed combustion with predrying of moist feed using bed sand
AssigneeDorr-Oliver Incorporated
InventorsElliot B. Fitch, Orris E. Albertson
Life of this patent
Estimating the term…
Abstract
Moist combustible matter is burned in a fluid bed reactor following a drying treatment in which the combustible matter is brought into contact with hot sand circulated from the fluid bed reactor. The water in the combustible matter is evaporated at a relatively low temperature in the drying treatment, thereby conserving heat in the system. The exhaust vapor from the drying treatment is handled separately from the reactor exhaust gases to condense the vapor therein before subjecting the remaining gas to odor-destroying high temperature.
Claims33
A process for combustion of moist combustible feed wherein said moist feed is first dried and then introduced into a fluidized bed of hot, inert, particulate material for combustion comprising, withdrawing a quantity of said hot particulate material from said fluidized bed, intimately contacting said moist feed with said hot particulate bed material to evaporate the water in the feed at a relatively low temperature, separating the dried solids from the gas stream containing the evaporated water, charging the separated dried feed and the particulate bed material associated therewith into said fluidized bed for combustion, treating the separated gas stream to remove and dispose of the water vapor therein and forwarding the balance of the separated gas stream for further use in the process.
A process for incineration of moist organic sludge wherein said moist sludge is first dried and then introduced into a reactor having a fluidized bed therein of hot, inert, particulate material to heat the sludge to incineration temperatures, comprising, withdrawing a quantity of said hot, particulate material from the fluidized incinerating bed to a drying zone, introducing moist sludge into said drying zone for intimate contact with said hot, particulate bed material to effect drying of said sludge by evaporation of the water fraction, conducting the water vapor away from said drying zone, condensing the water vapor and disposing of the liquid formed, exposing any non-condensible gases present in said drying zone to the odor-destroying elevated temperatures in said reactor, and charging the dried sludge and a quantity of particulate bed material into said fluidized incinerating bed for combustion of said sludge and reheating of said particulate bed material.
A sewage sludge incineration process wherein said sludge is first dried and then charged into a reactor having a fluidized incinerating bed of sand therein maintained at a temperature of at least 700.degree. C. to effect substantially complete combustion of the sludge, comprising, withdrawing hot sand from said reactor and introducing said sand into a drying bed, said hot sand maintaining said drying bed at a temperature of from about 80.degree. C. up to about 180.degree. C., passing a substantial flow of air through said drying bed to effect fluidization thereof, charging sewage sludge into said fluidized drying bed for intimate contact with said hot sand and fluidizing air whereby said sewage sludge is dried and the air becomes well moisturized, removing said moisturized air from the vicinity of said drying bed to a condensation zone, condensing the water vapor present in the air in said condensation zone, removing the liquid produced thereby for disposal, introducing the air from said condensation zone into said reactor to serve as at least part of the fluidizing combustion air for said fluidized sand bed in said reactor, any odors present in said air being destroyed by exposure to the combustion temperatures, and exhausting the gases from said reactor.
A combustion system for moist combustible feed comprising a fluidized bed reactor adapted to house a bed of inert particles, means for fluidizing said particle bed, an exhaust conduit connected to said reactor to conduct away reactor exhaust gases for ultimate discharge into the atmosphere, a dryer unit for drying moist feed prior to combustion, feed means connected to said dryer unit for introducing moist feed into said dryer unit, a first transfer means connecting said reactor and said dryer unit for withdrawing hot, inert, bed particles from said reactor and conveying said particles to said dryer unit, a second transfer means connecting said reactor and said dryer unit for withdrawing a mixture of dried feed and inert bed particles from said dryer unit and conveying said mixture to said reactor for combustion, a vapor conduit connected to said dryer unit for conveying water vapor from said dryer unit, a condenser connected to said vapor conduit to receive and condense said water vapor for disposal and means for conducting any non-condensible gas from said condenser to said reactor so that said non-condensible gas is subjected to the elevated temperature within said reactor.
A system for incinerating sewage sludge comprising a fluidized bed incinerating reactor adapted to house a bed of inert particles, blower means for furnishing fluidizing air to said reactor, an exhaust conduit connected to said reactor to conduct away reactor exhaust gases for ultimate discharge into the atmosphere, a dryer unit for drying sewage sludge prior to incineration, feed means connected to said dryer unit for introducing moist sludge into said dryer unit, a first transfer means connecting said incinerating reactor and said dryer unit for withdrawing hot, inert, bed particles from said incinerating reactor and conveying said particles to said dryer unit, a second transfer means connecting said incinerating reactor and said dryer unit for withdrawing a mixture of dried sludge and inert bed particles from said dryer unit and conveying said mixture to said incinerating reactor, said blower means communicating with said dryer unit for providing a substantial air flow through said dryer unit for removal of moist air from said dryer unit, a vapor conduit connected to said dryer unit, a condenser connected to said vapor conduit to receive said moist air and remove water vapor therefrom for disposal, a heat exchanger, a gas conduit having said blower means therein connected between said condenser and said heat exchanger to conduct non-condensible gas from said condenser and air from said blower to said heat exchanger for preheating, conduit means connecting said exhaust conduit to said heat exchanger to furnish hot exhaust gases from said reactor prior to discharge into the atmosphere for heat exchange with said non-condensible gas from said condenser and said air from said blower, conduit means connecting said heat exchanger with said incinerating reactor to conduct the preheated air and non-condensible gas to said reactor for use as at least part of the fluidizing air.
Dependencies are inferred from the claim text.