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Applications Analysis: Increasing the Effeciency of a "Pusher" Investment Casting Furnace Hearth
Casting Furnace Hearth
Armil CFS, a Chicago based distributor and fabricator of ThermoDyne microporous products, is looking to help one of its customers increase the energy efficiency of one of their “pusher” style investment casting furnaces, as well as reduce the cold face temperature of the hearth in order to provide less stress upon the metal at the base/floor. The hearth is 5’ wide x 20’ long, and operates continuously at 2,100°F. Currently, the composite lining of the hearth is comprised of 4.5” of Super Duty Firebrick, 4.5” of 2300 Insulating Firebrick, and 3” of Calcium Silicate material.
Due to increases in energy cost associated with the operation of the furnace, in addition to an increasing demand for process efficiencies with minimum capital expenditures, the customer is looking to achieve the following goals by re-insulating the hearth:
• Minimize the amount of heat lost through the hearth, thus ensuring the greatest possible heat containment, and, inversely, the least amount of energy necessary to keep the furnace at operating temperature.
• A steady state cold face temperature lower than 200°F for the metal shell upon which the insulation composite rests on the floor of the hearth.
By substituting the same thickness of microporous DynaGuard Board 18# material for the Calcium Silicate material being utilized in the current composite, the company would reduce the amount of heat energy being lost through the composite by as much as 50%, as well as reduce the cold face temperature by 25%.
Thermal Analysis & Comparison:
Thermal Analysis and Comparison chart
• The composite with the DynaGuard™ Board 18# material yields a cold face temperature 47°F lower than the composite containing the Calcium Silicate material.
• The composite with the DynaGuard™ Board 18# material yields a heat loss of 107.72 Btu/SF/Hr less than the composite containing the Calcium Silicate material.
• Over the course of a production year and given the size of the hearth (100 SF), the DynaGuard™ Board 18# material prevents the loss of approximately 94.3 million more Btu than the composite containing the Calcium Silicate material.
Financial Analysis & Comparison:
Given the differences in heat loss (Btu/SF/Hr) for the two composites, the following can be estimated for the amount of heat lost through the system in $/year for each:
Financial Analysis and Comparison
The composite utilizing DynaGuard™ Board 18# material saves $1,797.12/year over the composite with the Calcium Silicate material.
• The initial cost of DynaGuard™ Board 18# material can be easily justified on the basis of energy conservation alone.
The composite with the DynaGuard Board 18# material is the best one to accomplish all the objectives that the company set forth as their primary goals. It provides the greatest thermal management and financial gains, and performs at the given temperature levels almost twice as efficiently as the other materials currently being utilized.
For more information about how ThermoDyne’s DynaGuard™ Flexible, Ladle Liner, Board or Panel materials may be of use in your particular application, please contact ThermoDyne’s team of Application Engineers at toll-free: 866.741.5458.
- 1 KwHr = 3413 Btu
- $.065/KwHr = estimated average for energy costs. This figure may vary with facility location and amount of energy used.
- Calculations assume ambient air temperature to be = 80°F, with natural convection consistent with an indoor environment.
- Calculations assume steady-state.
- Calculations and information provided are for comparison purposes only, and are not intended for design specifications as individual scenarios for material use may vary.
- Photo used courtesy of Armil CFS
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