Method and Plant for Thermal Conversion of Solid Fuels

Abstract

The invention relates to thermal conversion of solid fuels with a low organic content and can be used in the fuel-processing industry. Conversion of oil shale or high-ash solid fuels comprises flue-gas drying of feedstock, recovering the solid phase as a heat-carrying agent, feedstock pyrolysis in a reactor, separating a gas-vapour mixture from the coke-ash residue in a dust-settling chamber, discharging ash, cooling flue gases, and combustion of the coke-ash residue. An inert material having an ambient temperature is supplied to the outlet of the coke-ash residue ignition chamber. The plant comprises, arranged in series, a reactor, a dust-settling chamber, a flash-process furnace, a heat-carrier cyclone, an ash cyclone, a waste-heat recovery system, an ash-discharge system and a bin for inert material connected to the outlet of the coke-ash residue ignition chamber. The invention allows for a more complete use of the oil shale energy potential and for obtaining ash with a reduced negative effect on the environment, which makes it possible to use the ash for recultivation of quarries resulting from oil shale mining.

What is claimed is: 
     
         1 . A method for converting oil shale or high-ash solid fuels comprising:
 flue-gas drying of feedstock;   recovering a solid phase as a heat-carrying agent;   performing feedstock pyrolysis in a reactor;   separating a gas-vapor mixture from a coke-ash residue in a dust-settling chamber; discharging ash, cooling flue gases, and combusting the coke-ash residue; and   controlling temperature in a flash-process furnace by supplying an inert material having an ambient temperature to an outlet of a coke-ash residue ignition chamber.   
     
     
         2 . The method according to  claim 1 , wherein the inert material is ash from a discharge system, the ash having a temperature of 10 to 200° C. 
     
     
         3 . A device for converting oil shale or high-ash solid fuels comprising:
 arranged in series a reactor, a dust-settling chamber, a flash-process furnace, a heat-carrier cyclone, an ash cyclone, a waste-heat recovery system, an ash-discharge system, wherein a bin for inert material is connected to an outlet of a coke-ash residue combustion chamber for temperature control in an ignition chamber of the flash-process furnace.