Wet vs Dry Gas Cleaning In the Steel Industry

Abstract

Deciding whether the gas should be cleaned by a “dry” system or a “wet” system requires a full consideration of all factors of which the capital cost is only one. Anticipating the various problems which might be expected and designing adequate measures for each calls for major engineering effort,but onlythen can a best choice be made. The principles which govern the above are illustrated by a typical selection of gas cleaning equipment to be used as part of a BOF steel making installation. Two entirely different gas cleaning systems are presently in BOF service in North America. Both will do an excellent job if properly designed. Either system will cost in excess of $2,000,000 and will require careful control and large amounts of electrical power. One system, the dry electrostatic precipitator, requires humidification of the gas; protection against explosions; elaborate electrical controls, insulators, etc.; and a rugged handling system for the bone dry dust collected. The other system, wet washing with water, Is easier to control but uses large quantities of water and electric power. As in the case of the “dry” system, handling the dirt collected is a difficult problem requiring careful study and choice of equipment. In either case the dust may be discarded or reused, but it must be handled with care lest it become an air or stream pollution problem all over again.