Accretion Control in Sponge Iron Production Kiln using Fuzzy Logic

Abstract

Sponge iron is the product generated by direct reduction of iron ore with aid of either carbon or natural gas under controlled temperatures and pressures within a rotary kiln. However the performance of rotary kilns is usually adversely affected by the formation of accretion. This accumulation of sintered solid particles which form rings along the length of the kiln hinders material flow, lowers productivity and life span of the kiln. To maintain the quality of sponge iron and improve on performance of rotary kilns, there is need to minimize accretion build up in the kiln. However due to the nonlinear nature of the reduction process dynamics, it is difficult to control accretion build up in the kiln. This paper proposes the control of accretion build up through the application of Fuzzy Logic control. The controller receives partial and imprecise data from field instruments and is able to maintain product quality under dynamic process conditions. MATLAB Fuzzy-Toolbox was used to model and simulate the design. A comparison is made between the designed Fuzzy system and the PID controller. Simulation results show that it is possible to reduce accretion build up from 27 % when using PID controller to 14.6 % with the use of Fuzzy control.

Keywords: Accretion, Fuzzy Logic, Kiln, Sponge iron