Vertical ring shaft kiln

A vertical ring shaft kiln comprising:

• a vertical burning region having an intermediate sintering zone defined by a first wall and a second wall, the second wall being opposite the first wall, and defining a gap therebetween, the first wall and second wall being of a ring shape one inside the other;
• a support wall connecting a bottom part of the first wall and a bottom part of the second wall with an outlet;
• a plurality of nozzles having outer nozzles at the first wall and inner nozzles at the second wall, said plurality of nozzle adapted to develop a flame in an adjustable manner throughout a length of the gap by injecting a fuel and a gas inside the sintering zone, wherein said plurality of nozzles comprise outer and inner auxiliary nozzles positioned at a distance from the inner and outer nozzles, the outer and inner auxiliary nozzles adapted to inject oxygen or air inside the sintering zone;
• a plurality of heat sensors disposed at an outer side of the first wall so as actual heat exchange information at the first wall;
• a detection unit cooperative with said plurality of heat sensors so as to produce a thermal map of the sintering zone and adapted to fine over-burned or unburned spots by comparing a detected heat value with a homogenous heat pattern set by a threshold heat value;
• a control unit connected to said detection unit so as to prevent the over-burned or unburned spots by changing a vertical flow speed or by activing an adjacent nozzle or auxiliary nozzle of the plurality of nozzles;
• and
• a roller crusher positioned at the outlet of said vertical burning region, said roller crusher being fed by sintering material so as to determine the vertical flow speed.