Implementation of Metal Casting Best Practices - EERE - U.S. ...

within an overall process heating system can vary significantly. Exhibit 4 compares the
efficiency and the melt loss of the various types of furnaces the industry employs. As the Exhibit
reveals, the efficiency of melting operations can vary from 7% (gas crucible, lower end) to 76%
(induction, aluminum, upper end). These widely varying thermal efficiencies combined with
high energy costs imply that casters should be able to identify many opportunities to improve
furnace operations and thus generate significant energy (and cost) savings.
Exhibit 4: Efficiency and Melt Loss for Different Die Casting Furnaces
Melting Furnace Common Use Melt Loss Thermal Efficiency
Cupola Iron 3-12% 40-50%
Electric Arc Steel 5-8% 35-45%
Immersion Zinc N/A 63-67%
Electric Reverberatory
Aluminum
Zinc
1-2%
2-3%
59-76%
59-76%
Gas Crucible
Aluminum
Magnesium
4-6%
4-6%
7-19%
7-19%
Gas Reverberatory
Aluminum
Zinc
3-5%
4-7%
30-45%
32-40%
Gas Stack Melter Aluminum 1-2% 40-45%
Aluminum 0.75-1.25% 59-76%
Copper-Base 2-3% 50-70%
Induction
Magnesium 2-3% 59-76%
Iron 1-2% 50-70%
Steel 2-3% 50-70%
Source: Schwam D., Wallace J.F. and Wannasin J. “Energy Efficiency of Aluminum Melting in Die Casting Operations”, CastExpo,
St. Louis, April 2005, Presentation T-072.
The ITP BestPractices portfolio offers the Process Heating Assessment and Survey Tool
(PHAST), a software application that can aid metal casters in identifying opportunities for saving
energy in process heating equipment such as melting furnaces, heat treatment furnaces, and
holding furnaces. PHAST provides plant personnel with the tools to survey furnaces and to
produce a report that identifies ways to increase the energy efficiency of individual pieces of
equipment throughout the entire heating process. Metal casters can assess equipment
performance under varying operating conditions by changing the input parameter values used by
PHAST.
The PHAST application offers three major benefits to metal casters:
• Focuses Improvements on Energy-Intensive Equipment – Using the metal caster’s
specific heat input and furnace operating data, the application reports the quantity and
cost of fuel and electricity that each piece of equipment uses annually.
• Calculates Potential Energy Savings – The application assesses energy-saving
opportunities by comparing the performance of individual pieces of equipment under
various operating conditions with that of a wide variety of retrofit technologies.
• Identifies Energy Waste – PHAST evaluates all areas in which energy is used, lost, or
wasted and constructs a detailed heat balance report for melting, holding, and heat
treatment furnaces.
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