Simple Solutions That Work! Issue 7

7 b. Transfer pumps are also a good investment as they transfer metal to the ladle much faster and are safer for the metal handlers. The new overflow pumps available are very efficient and provide a less turbulent transfer into the transfer ladle see movie clip below! WATCH THE VIDEO 5. Pre-heated combustion air through a regenerative combustion system, added to the features mentioned above, will drive the energy consumption down to 900-to-1050 BTU/pound of aluminum melted in a fully utilized melter Because of the efficiencies of the first four items above, the added cost of the regenerative combustion system takes about 8,400 hours of full capacity operation per year of $3.00/MCF natural gas to yield a 60-month ROI. Escalating energy costs can shorten the ROI drastically. These burners work in pairs and as one burner is firing the other is exhausting the products of combustion into the bed of tabular aluminum balls which heat up to the exhaust temperature then the burners switch and the combustion air is drawn through that heated media to preheat the combustion air significantly. a. This method of preheating and charging normally provides about a 20-to-24 month ROI, based on 5,200 hours of melting per year. 4. Circulation of the molten metal within the furnace bath (from the charge well-to-the-thermal head chamber-and-back) has the advantage of saving another 9-to-12% of the energy that it takes to melt the aluminum, reduces melt loss through enhancing more rapid melting and reduces sludging by convectively maintaining a homogenous bath temperature. In recent years great strides have been made in improving molten metal pump efficiency and drastically reducing their need for maintenance. a. Typically, circulation pumps, and the wells into which they are designed, have a 24-to-28 month ROI. NOTE: If the first four items above are furnished on a furnace, a fully utilized central melter will melt at about 1235 BTU/pound in a SGI radiant roof-fired reverb furnace, and at about 1,590 BTU/ pound in a SGI high headroom wall-fired furnace. This is all being accomplished in a wet-bath reverb furnace, which absolutely provides the aluminum foundry the lowest metal melt loss by several percentage points. REGENERATIVE BURNERS “CYCLE A” REGENERATIVE BURNERS “CYCLE B” Continued on page 8