Cross-over Repairs and Installation of Pressure Equalizing System at POSCO Gwangyang

摘要

The cross-over is a critical part of the external combustion chamber stove because relative movements of both domes due to thermal expansion and pressure must be absorbed in the cross-over construction. To allow these movements the cross-over shell is disconnected in the center and a sliding joint is present in the refractory. The sliding joint in the refractory forms a weak point in the construction and can result in flow of hot gases or hot blast to the outer shell Therefore hot spots frequently occur on the shell of a cross-over. This paper presents a solution to this problem. The Danieli Corus cross-over design includes a pressure equalizing system. The so-called equalizing line connects the void behind the refractory with the cold blast supply. This allows the sliding joint in the refractory to be sealed from the outside, because the pressure equalizing takes place with cold blast. A special adaptation to the equalizing line results in a constant purging of the compensators in the cross-over shell with cold blast, This provides cooling to the outside shell and avoids NO{sub}x from entering the shell area where it can cause stress corrosion. This system in combination with a flexible seal of the joint in the cross-over refractories prevents the occurrence of hot spots on the cross-over shell and bellows. Equalizing systems were installed at POSCO Gwangyang Blast Furnace Nos. 1 and 2 stoves, when Danieli Corus repaired the crossover's of these stoves. Operating experiences with the new pressure equalization systems are positive.