North American StepFire ™ Burner Control System General Overview
Bulletin 8061
Firing Lane Atmosphere Temperature
StepFire™ is an advanced control system that modulates fur- nace energy input according to demand requirements from a programmable logic controller (PLC), personal computer (PC), or temperature controller. It adjusts the thermal input by cycling multiple burners (within a zone) from high-to-low for controlled periods of time. FEATURES/BENEFITS — Superior Temperature Uniformity StepFire's high-to-low burner control and produces maximum heat transfer of the furnace gases for optimum temperature uni- formity, resulting in better product quality and increased produc- tion (see Figure 1). — Lower Fuel Usage StepFire operates on-ratio to provide ideal efficiency of heat transfer with minimum fuel. — High Thermal Turndown Since StepFire elongates the burner rotation time as heat demand drops, better thermal turndown is produced. StepFire's excess air breakpoint feature throttles the fuel and adjusts burner firing times to achieve further turndown when required. — Reduced NOx Emissions At high fire, NOx reduction takes place because of more thor- ough mixing of the products of combustion with the hot burner gasesand low excess air (XSA).
2538 F
2534 F
2523 F
Product Temperature
2520 F
0
30
60
90
120
Time, seconds
• Ceramic Tunnel Kilns • Periodic Kilns • Heat Treat Furnaces • Forge Furnaces • Aluminum Melters/Holders TYPICAL APPLICATIONS TYPICAL SYSTEM • Any Burner whose heat release characteristics are optimized at high fire • Air Cycling Valves • High/Low Ratio Regulator • Flame Supervision • StepFire Control System • Galvanizing Tanks • Crucible Furnaces • Reheat Furnaces • Scrap Preheaters Figure 1. Furnace atmosphere temperature vs. product temperature, showing less than 1°F variation in temperature uniformity (reproduced from actual data).
Ignition Transformer
Figure 2. Typical StepFire burner module piping schematic.
Igniter
Burner
Regulator
Shutoff Valve
Gas Header
Ball Valve
Air Cycle Valve
Air Header
Flame Detector
Made with FlippingBook flipbook maker