Parallel-flow regenerative shaft kiln and method of burning carbonate rock

A co-current/counter-current regenerative shaft kiln for burning and cooling material, such as carbonate rock, comprising:

• two shafts which are operable alternately as a burning shaft and as a regenerative shaft and are connected to one another by means of a connecting duct;
• wherein in the flow direction of the material each shaft comprises a preheating zone for preheating the material, a burning zone for burning the material and a cooling zone for cooling the material;
• wherein the cooling zone comprises a cooling gas inlet for admitting cooling gas into the cooling zone and a cooling gas removal device for discharging cooling gas from the shaft;
• wherein, configured downstream of the burning zone in the flow direction of the material is an after-calcination zone which is configured and adapted such that it effects after-calcination of the material exiting the burning zone at a gas temperature of 800° C. to 1100° C., wherein a gas separation zone for separating the cooling gas and the fuel gas is configured between the after-calcination zone and the cooling zone, wherein the gas separation zone is configured as an annular space, wherein the ratio of the internal diameter of the gas separation zone to the external diameter of the cooling zone is 0.4 to 0.9.

A method of burning material, such as carbonate rock, in a co-current/counter-current regenerative shaft kiln having two shafts which are operated alternately as a burning shaft and as a regenerative shaft and are connected to one another by means of a connecting duct, wherein the material flows through a material inlet into a preheating zone for preheating the material, a burning zone for burning the material and a cooling zone for cooling the material to a material outlet, comprising:

• admitting a cooling gas into the cooling zone, wherein the cooling gas heated in the cooling zone is discharged from the cooling zone of the shaft via a cooling gas removal device and wherein each shaft is gaseously connected to the connecting duct;
• subjecting the material exiting from the burning zone to after-calcination in an after-calcination zone downstream of the burning zone in the flow direction of the material at a gas temperature of 800° C. to 1100° C., wherein a gas separation zone for separating the cooling gas and the fuel gas is configured between the after-calcination zone and the cooling zone, wherein the gas separation zone is configured as an annular space and wherein either the ratio of the internal diameter of the gas separation zone to the external diameter of the cooling zone is 0.4 to 0.9, or the ratio of the length of the gas separation zone to the external diameter of the cooling zone is 0 to 1.