Process and plant for the thermal treatment of fine-grained solids

A plant for at least one of a chemical and a physical treatment of granular solids, the plant comprising:

• a fluidized-bed reactor with a reactor interior;
• a solids supply conduit configured to introduce the granular solids into the fluidized bed reactor;
• a gas supply tube configured to supply a process gas from below, wherein the gas supply tube opens substantially centrally into the fluidized-bed reactor;
• a cooling tube disposed relative to the gas supply tube so as to form an annular cooling duct between the gas supply tube and the cooling tube, the annular cooling duct being configured to cool the gas supply tube and the process gas, the annular cooling duct being connected with a coolant source configured to supply a coolant with a temperature of below about 400° C.;
• and
• outlet openings disposed in the cooling tube,
• wherein the fluidized-bed reactor is a Venturi reactor in which the cooling tube opens into a flared portion with the outlet openings connecting the annular cooling duct with the reactor interior, and wherein the cooling tube adjoins the gas supply tube and extends substantially parallel to the flared portion of the reactor.