Atmosphere Furnace Technology Integrates Expert SystemsPatrick Weymer
Ipsen International, Inc.
U.S. energy production is currently much lower than production. A full 17% of energy in the U.S. is consumed in manufacturing process heating. There has been a challenge by the government to improve this. Ipsen has chosen to seek improvement on three fronts.
1) efficiency
2) productivity
3) improved performance
IROM HORSE is a batch furnace system for carburizing that illustrates the strides made in this direction. [Click IRON HORSE to see the "pdf" brochure on the Ipsen web site.] Going beyond standard technology, the Iron Horse uses Recon III burners, muffles, and Super Carb atmosphere to drastically reduce production and energy costs. We will discuss the various aspects of this system.
Recon III Burners feature individual controls at each burner, which makes them 75 - 76% fuel efficient (this is 10-15% better than Ipsen's efficient U-tube burners. Additionally these burners exceed even Europe's toughest NOx emission requirements.
SurperCarb is a concept that allows Natural Gas (or other gaseous carbon source) to be cracked with air directly in the carburizing furnace, eliminating the need initial cost, energy needs, and operating costs of a separate "cracker" for atmosphere production. The basic reaction is:
CH4 + 2.5 x Air (0.2 O2 + 0.8 N2 -> CO + 2H2 + 2N2
The air and natural gas are injected outside a muffle in the carburizing furnace. A CO analyzer is used to control the process. A constant flow of Natural gas is maintained while the air flow is regulated based on the analyzed output. When operated a low temperatures is is necessary to add CO2 for proper atmosphere maintenance. During "open door" purging is the only time when the Natural gas flow has to be increased beyond its usual low flow rate. The net result is that about 1/6th as much natural gas is consumed as with traditional endothermic atmosphere production. When cycle time are very short, higher flows and CO2 additions are required since the "cracking" is time as well as temperature dependent. Openings in the hearth floor, and circulation fans in the roof allow atmosphere to be drawn up very uniformly through the load being carburized. The presence of the muffle also acts as a temperature equalizer which help the load carburize more uniformly than in traditional furnaces. This type of carburization requires very clean workpieces, so a two phase washing system is integrated into Iron Horse.
Another element of the system is Carb-o-Prof which is a PC based expert system and control that can calculate the recipe, control the atmosphere, and model the actual progress of the load. It controls through a slow-acting air control valve which is controlled to maintain the desired carbon potential.
The savings of this system can be summed as follows:
Gas use reduction: 80% (compared to traditional endo gas)
Total energy reduction: 50%
Elimination of generator, space, and maintenance (about $10k - $28k / year).
20% improvement in cycle times (less heat-up spread) or 120% more thruput.
Finally lets talk about Automag. This is the PC based control system designed to be able to run a lights-out operation. Automag schedules loads and transfers to optimize the use of the carburizing unit an eliminate as much idle time as possible. With Automag productive furnace time of 7400 hours compares to 5000 hours for a regular 3-shift furnace. Because all transfers (cleaning - preheat - carburize - quench - post clean - temper) are automated personnel hours are reduced from 5000 to about 3400 for the same set up.
Automag communicates with the Carb-o-prof units and all of the transfer PLC (programmed logic control) boards to accomplish its task. It also features libraries of material responses, and maintenance requirements to keep everything running smoothly. A plant overview can show operators the status of all loads running within a plant, and show a model of carburization progress of any specific load.
Finally, a little about developments for the future.
1) Integration of wireless communications into Automag for car control. 2) Trackless EGV cars for load handling through the plant.