Simplification of the Calcine Transfer Control System Architecture for Ferronickel Projects in System Reliability Assessment

Abstract

The Rotary Kiln-Electric Furnace (RKEF) technology is the most commonly known method for processing rich nickel ore because of its effectiveness. Before being smelted in the electric furnace, the ore must be calcinated in the rotary kiln to remove unnecessary impurities. Between these two leading devices, there is an unfailing need for effective calcine transfer system. During WIKA's first ferronickel plant project, the calcine transfer system's design was subcontracted to third parties, resulting in the supply of transfer car, hot charge crane, and hot charge system as a complete mechanical package including instrument & control system. With the three subsystems, three different PLC systems, one for each, were supplied. The presence of these local PLCs significantly decreased the reliability of calcine transfer control system. In WIKA's current ferronickel project, the calcine transfer system is done differently, taking advantage of the first project's extensive experience. The new design of instrument and control system is intended to optimize the use of primary PLC-SCADA system by removing third parties local PLC. In this paper, the current in-house design's reliability is examined and compared to the previous one. The control system architecture diagram of both designs is used to determine their corresponding fault tree model. The analysis focuses on the control system's component reliability. The top event availability values are then quantified using the Boolean algebra of the fault tree model, the failure rate and repair rate data. At the end of the study, with less local PLC, the calcine transfer system's availability is better, and it is even better if the primary PLC-SCADA system handles all the calcine transfer processes.