The plot below shows surface and bottom molten metal temperatures before and after about 5 minutes of proper circulation. The bottom and surface temperatures start out with roughly 100C difference. Within 5 minutes of turning on the circulation pump, the temperature uniformity is within a 10C.
There are two immediate observations that can be made:
- The furnace temperature needed to keep the bottom of the melt within a desired range has just dropped 40 to 50C. This translates into immediate energy savings.
- The pour temperature no longer has to compensate for temperature non-uniformity in the melt. This can also translate into reduced energy savings.
Furnace manufacturers agree that an ideally designed furnace produces 10% to 15% energy savings when a properly sized circulation pump is added. Experience has proven that a non-ideal furnace design can improve energy efficiency by as much as 30% with a proper circulation pump.
This also means that a furnaces production throughput can be significantly enhanced with proper circulation.