Design of control system for compound heating resistance furnace for optimization of furnace efficiency

Abstract

The proposed work examines the performance of control system in a Compound Heating Resistance (CHR) furnace heated, using two different heating elements, Silicon Carbide (SiC) heating rods and Molybdenum Di-Silicide (MoSi ) 2 heating elements for 1600ᴼC working chamber temperature. The system under study consists of Programmable Proportional Integral Derivative (PPID) controller, Thyristor (is also known as Silicon Controlled Rectifier) power pack, recrystallized alumina tubes, sensing elements: thermo-couple, Pt-Pt/13%.Rh, semiconductor based circuit that controls power and current to system according to the requirement (step down) and thereby control voltage automatically with transformer (depending on size of working area, and 53 amp (I), 220 V for single phase, reduced to 60 V by a step down transformer) auto current limiting facilities. Present work is designed for programmable as also for nonprogrammable type of cycles of operations set before starting the furnace within maximum working temperature of 1600ᴼC to achieve objectives, like, saving of amperage (current consumption of 53 amp) and power at reduced voltage (40V), long life of the heating elements (2 years and more) and optimization of thermal efficiency (60%) for high working temperature 1600ᴼC for long hours of operation in a CHR furnace.