Küttner GmbH & Co. KG (Essen, Germany):

Schott R., Dr. Eng., e-mail: r.schott@kuettner.com

Pulverized coal is the most wide-spread and often most efficient reducing agent in blast furnace practice. The most is the part of pulverized coal injection (PCI), the most is economical efficiency of fuel consumption. To provide high part of PCI usage it is necessary to create conditions for quick coke gasification in tuyeres and in the area of coke circulation in front of tuyeres. It is underlined that gasification degree should be maximal possible, otherwise injection can have negative effect on gas penetration of charge materials. To achieve this aim, Kuettner has developed and uses now its own model of gas flows durinf PCI injection. The first step of optimizing existing PCI systems is to reduce the transport and injection gas to a minimum. From this follows that existing dilute phase PCI systems should be changed to dense phase PSI systems. The second step of optimizing existing PCI systems is to improve and accelerate the coal gasification within the tuyere and the raceway by using the Oxycoal technology. The third step of optimizing existing PCI systems is to use the PC preheating in combination with the Oxycoal technology which enables a further acceleration of pulverized coal gasification within the tuyere and the raceway of the blast furnace. Another way to realize high PCI rates converted by the blast furnace process uses high oxygen enrichments of more than 30 to 35 % of the hot blast. In that case a simple dilute phase PCI system may be sufficient. Also the combined injection of pulverized coal and natural gas may be interesting for blast furnace operators who have cheap natural gas.

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