Investigating performance of compound heating furnace subject to heating by two elements and (Silicon Controlled Rectifier) SCR control at 1600ᴼC

Abstract

The present research examines the performance of a resistance heating furnace using two different heating elements, Silicon Carbide (SiC) heating rods and Molybdenum Di-Silicide (MoSi2) to raise working chamber temperature to 1600ᴼC. SiC rods are used first, starting from the beginning (ambience) temperature 35ᴼC up to 1300ᴼC, followed by MoSi2 heating elements to raise chamber temperature from 1300ᴼC to set temperature at 1600ᴼC. Transition from SiC to MoSi2, heating system is uninterrupted, and swift in heating element effected by inter-locking system (an electronic device or an electro-magnetic system) without any drop in effect. The system under analysis consists of Programmable (Proportional-Integral-Derivative) PID, (Silicon Controlled Rectifier) Thyristor power pack, recrystallised alumina tubes, sensing elements: thermo-couple, Pt-Pt/13%.Rh, semiconductor based circuit that controls power and current to the system 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 60V by a step down transformer) and auto current limiting facilities. Present analysis is designed for programmable and also for non-programmable 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 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 Compound Heating Resistance (CHR) furnace.