Design of a Dry Slag Granulation Plant for Blast Furnace No. 5 of Severstal

This article discusses the engineering and computational methodology of designing the main units of a blast-furnace slag dry granulation plant with a capacity of 1 million tons of slags per year, also intended for the recovery of slag heat. This plant can replace the slag wet granulation plant at blast furnace No. 5 at the iron and steel works of Severstal of the same capacity. The method can be used to estimate the radius and rotation frequency of the disk for spraying a slag, mechanical power to the disk drive, granulation chamber (GC) diameter that ensures the solidification of slag droplets, temperature of slag granules at the outlet of the GC, amount of heat transferred by convection to the air and by radiation to the walls of the GC, flow rate of air supplied to cool the slag, changes in the temperatures of the slag and air on fluidized bed grates (FBGs), size of these grates, loss of air pressure in the plant, and power consumption for the fan drive, amount of slag heat disposed of in the plant, and possible generation of electricity due to it. Recommendations on the shape of the side wall of the GC are given. The findings revealed that for a plant with a capacity of 1 million tons of slags per year with a diameter of granules no more than 2 mm, the disk radius should be approximately 0.2 m, with a rotation frequency of 500 rpm and disk drive power of 5.1 kW. The required diameter of the GC at the flight speed of slag droplets of 10.4 m/s is approximately 14.4 m. The slag is cooled in the GC from 1500℃ to 1030℃ and then to 150℃ on three FBGs. Cooling air with a flow rate of 34.8 nm3/s in FBGs is heated to 640℃ and then to 800℃ in the GC. The fan drive power for is approximately 40 kW. In the plant, approximately 43 MW of heat can be disposed for steam generation, and up to 18.5 MW of electricity can be obtained due to it.