Design of each reactor and their integration with each other is important such that furnace off gas exits the system at a low temperature to the extent possible and at the same time scrap is heated to the desired temperature and steel of required quality is tapped.

Furnace

The furnace is refractory lined and has a provision for injection of carbon and oxygen. Oxygen can be injected both at high speed to promote decarburization and at low speed to promote post combustion.

Preheater

A preheater is installed at the top of furnace to preheat the scrap by the waste gases flowing upward from the furnace. For scrap preheating residence time (R T) of the waste gas in the preheater

(1)

                 
should be maximum. D is diameter of preheater and Q is volume flow rate of furnace gases. Both D and Q are important. For a given Q, diameter of preheater must be such that furnace gases can cool within  to  from . The exit temperature of gas from the preheater is the inlet temperature of gas to the recuperator. Scrap size is also important to heat scrap to the desired temperature. Smaller size scrap can be preheated efficiently.