Simple Solutions That Work! Issue 7

Contact: DAVID WHITE david.white@theschaefergroup.com 6. Recuperators for combustion air pre-heat offer the faster return on your investment for pre-heating combustion air. They come in various sizes and are easily retrofitted in any size furnace for you to start saving energy instantly. The BTU’s required to heat the combustion air up to 700° F are saved immediately upon installing this heat exchanger. Customers are realizing a 19-25% reduction in fuel usage with these heat exchangers. At today’s gas prices ROI’s are averaging 20 months. HARD USE ENERGY NUMBERS Let’s talk some “hard energy” use numbers. A. Gas-fired 1. A well designed and fully utilized radiant roof-fired melting furnace will melt for 1,500-1600 BTU/lb. (34% effic.): 100% cold metal charging. 2. With the addition of the “easy” energy recovery enhancements of the lining super insulation package, sow pre-heat hearth and molten metal circulation = 1,235BTU/lb. ( 41% effic. ). 3. The more expensive energy enhancements start with: a. Recuperation , in conjunction with 1&2 above, = 1,095 BTU/lb. ( 50% effic.). Electric: Connect .31KW/# of metal melted it uses about .25-.27KW/# of metal melted about 48% efficient. D. Tower or Stack Melters: Generally connect about 1800BTU’s/# of metal melted and use about 1,000BTU’s/# of metal melted when the stack is kept full, which puts them (depending on their fixed heat loss) into the 74% efficiency range. ENERGY VALUES OF THE MOST COMMONLY USED ENERGY SOURCES: • Natural gas 1,050 BTU/CF Some countries are less, some are more! • 100,000 BTU/therm • 1,000,000 BTU/decatherm, or 1,000 CF • Electric-3,412 BTU/KWH • #2 Fuel Oil - 138,000 BTU/U.S. gallon • Propane - 92,000 BTU/ U.S. gallon in liquid BOTTOM LINE! The information in this article is meant to provide you with ways of saving energy which even at today’s prices is still one of your most expensive costs to operate a foundry or die cast facility. Know what your present melting and holding energy uses are now and meter them. A Peter Drucker’s truism “If you can’t measure it, you can’t manage it.” This is just a relevant today as it was years ago. 7. Well Covers should be placed on any open well that will be out of production for more than 30 minutes. At higher temperatures 1400° F you lose approximately 7800 BTU’s/square foot/hr of surface area off an open well with some dross on the surface. Since the average charge well on a large reverb is about 30 square feet, that is 234,000 BTU’s/hr off that well. Of course none of these items are free but the cost vs return on investment make most of these worthwhile investments for your furnaces. b. Regenerative burners , in conjunction with 1&2 above, = 940 BTU/lb. (72% effic.). B. Electric Radiant-roof .23-.24 kwh/# electric reverb 784 btu/lb. 66.7% 1. with molten metal circulation 21-22 kwh/# 687btu/lb. 72.8% 2. immersion element melter 18-19 kwh/# with molten metal circulation 655 btu/lb. 76.3% C. Crucible furnaces: Gas: Connect 3,000BTU”s/# of metal melted uses about 2,300BTU’s/# Melted 32% efficient 8