|Fig. 1. Car-bottom heat-treating furnace |
Hauck Manufacturing Company has been
providing Pulse-fired combustion systems in North America for more than 20 years with many successful installations. Pulse firing was first introduced in Europe more than 30 years ago.
|Fig. 2. Typical heating cycle |
High-performance control components are essential for all pulse-fired combustion systems. Due to rising fuel costs and ever-increasing concerns about product quality, there has been an increased demand for pulse-fired combustion systems in recent years to meet these challenges. In addition, improved control technologies using PLC-based control systems are being incorporated to enhance the performance and flexibility of new state-of-the-art pulse-fired combustion systems.
In mid-2005, Hauck, in conjunction with Robbins Industrial Furnace Company (formerly “The Furnace Works”), proposed a unique pulse-fired combustion system to Superior Forge and Steel Corporation (Superior) in Lima, Ohio. This system was to be used in a retrofit project of a car-bottom heat-treating furnace.
Furnace design was performed by The Furnace Works, Inc. (TFW) of Sheffield, Ohio. TFW was founded in 1994 to provide innovative solutions for industrial-furnace refractory and insulation applications. The company also provides services including combustion-system design and service and new furnace design and construction. TFW was reorganized to Robbins Industrial Furnace in January 2007.
Superior is an ISO 9000-certified company formed in 1991. The company’s primary product is forged, hardened steel rolls for hot and cold rolling of ferrous and nonferrous materials. Other products include commercial ingots, specialty forging, heat treatment and machining. The company also maintains facilities in Pittsburgh and New Castle, Pa.
This furnace project was to rebuild a furnace approximately 32 feet long x 15 feet wide x 17 feet high. The project included a new car, ceramic-fiber lining, flue modification and a new combustion system. A typical load consists of steel rolls of varying sizes with weight ranging from 60,000-130,000 pounds. The required heating cycles are very long with common cycles being four days or longer. The maximum furnace temperature is 1800˚F. Temperature uniformity of +/-10˚F throughout the heating cycle was needed to obtain the required steel metallurgy. The product cycle heats the load from ambient to 1800˚F with long holds at various temperatures followed by a controlled cooling cycle. A typical heating cycle is shown in Figure 2.