Newsletter 8 - Scrap Preheater Increases Melt Deck

Scrap Preheater Increases Melt Deck Throughput While Saving Electricity

What started out as an electricity conservation project resulted in an effective process/product technology innovation for electric induction foundries. Tests of the R.J. Cyr Co. Scrap Preheater demonstrated its ability to:

increase melt deck throughput with zero staff increase

eliminate metal splash

improve charge handling flexibility

reduce energy costs by 200kWh per ton melted

This scrap preheater process also reduced employees’ exposure to heat and metal splash, and improved the quality of the air both inside and outside the foundry. Because scrap preheaters use cost-efficient natural gas, preheat charges required less melt time, and less electricity. Net energy savings was estimated to be 11%. The challenge since then has been to quantify that energy savings under “real-world” conditions.

Now, we can.

Production at Advanced Cast Products (Easton, MA) documented over a 12-month period, shows the Cyr Scrap Preheater saved, on average, 200 kWh per ton of scrap processed. According to Larry Holland, Manager of Plant Engineering, this produces a net energy cost savings of more than 10%. “Here in the northeast,” he says, “we pay the highest unit cost in the country, while competing with foundries whose energy burden is often 50% lower. The Cyr system literally gave us back our competitive stance.”

The Scrap Pre-heater also addresses other problems common to electric arc furnaces. “The Preheater burns off water trapped within scrap stocks, and brings scrap to a uniform temperature throughout the load prior to its entering the furnace,” explains Holland. It takes just 6 minutes to heat the scrap to target temperature.

In addition, because preheated scrap enters the furnace at 800-900°F, melt time is reduced from 29 minutes to 20 minutes. The shorter melt improves throughput, while reducing the risk to workers of molten metal splash.

An afterburner operating at 1400°Fdrives off NOx and combustible gases, and a cyclone collects particulate. Performing at efficiencies of 94% and above, the cyclone (in conjunction with the afterburner) leaves the air cleaner than “outside” air, with SO2 , NOx , CO, VOC and particulate levels below the standards that prevail in all 50 states, and all 10 provinces.

System instrumentation assures that each load is 1500 lbs. This is the charge weight determined to be most efficient at Advanced Cast Products, although the system is scaleable to 4000 lbs. The afterburner, like the preheater, uses natural gas; both are rated at 2.5 million BTU.

Of course, this isn’t the first time a preheater has been marketed to electric foundries. “We investigated several options,” says Holland, “but found them lacking in terms of both credible energy savings projections and consistency of drying. The reality of purchasing scrap as a raw material is that material often arrives wet, and in winter, there’s impacted snow. Use it before it’s thoroughly dry and you’ll have an explosion where people can be badly burned. Proper preheating is the best prevention.”

According to R.J. Cyr Co. President, Randy Cyr, there hasn’t been a cost-effective way to preheat foundry scrap before now. “Other methods have used gas to drive heat through holding devices – or blasted flames at scrap on vibrating conveyors” he says. “This process is a thermal and material handling solution.”

CGRI (Canadian Gas Research Institute), the Ontario Ministry of Energy, Gas Technology Canada, Natural Resources Canada, the Ontario Ministry of the Environment, and several gas utilities also contributed to the development and testing of this cost-effective, environmentally friendly scrap preheater.

“Our bottom line is that rather than spending 18-20 minutes to complete three functions, the preheater allows the job to be done in six. Given that as an option, we think it’s wasteful not to preheat this way.”