The operation of the worldwide largest coke dry cooling plant (KTK) of the newly built Coking Plant Kaiserstuhl in Dortmund was started in March 1993. In contrast to the usual wet quenching which permits no recovery of energy from the red hot coke and which causes considerable emissions, in dry cooling the coke is filled into a fireproof cooling shaft lined with masonry and is cooled with a cooling gas that runs in a closed cycle.