Manual Manual … on an all-ceramic shell-and-tube heat exchanger for … The exchanger was designed to allow maintenance without furnace shutdown and soot … 4720 44th Street SE, Kentwood, MI 49512? 616-551-5420 phone? 616-551-5424 fax? www. heatxfer.com Turning waste to energy, liabilities to assets and visions into reality. 1 CASE HISTORY • HX-97-1 Since 1970, Heat Transfer International has designed and supplied industrial furnaces that utilize metal heat exchangers. In the early 1980s …

CASE HISTORY • HX-97-1 Since 1970, Heat Transfer International has designed and supplied industrial furnaces that utilize metal heat exchangers. In the early 1980s, development was started on an all-ceramic shell-and-tube heat exchanger for use in melting furnaces, incinerators and similar processes where acidic, high temperature, or particulate-laden flue gas prohibits the use of metals One of the country’s largest aluminum producers purchased ceramic exchangers for two reverberatories. The first went on line in late summer 1985 and the second the following October. The former, described herein, contains tubes made by the three major silicon carbide manufacturers and zoned according to anticipated service severity. The ceramic selection was based on a field test program conducted in this customer’s plant for 18 months. The exchanger was installed directly above the main flue, and the combustion air ductwork, combustion air fan, soot blowing platforms, etc., are all well above the furnace. SPECIFICATIONS 60,000 lb secondary aluminum melting furnace ? 12 million Btu/hr high fire rate with ambient combustion ? air 2,500 to 3,500 lbs/hr continuous tapping ? Primarily 5,000 series aluminum alloy ? Zoned furnace with 45,000 lbs in main chamber, 15,000 lbs ? in holding chamber One burner in holding chamber, two burners in melting ? chamber Scrap varies from 50 to 70 percent of charge ? Melting chamber designed for firing of ingots on a dry ? hearth and scrap melting in the bath Chlorinated fluxing 20 minutes out of every hour ? 1,400°F average bath temperature ? 1,750°F average furnace temperature, with excursions to ? 2,200°F 1984 average melt/hold fuel consumption was 2,850 Btu/lb. ? SCOPE Redesigned the control system to accommodate an all- ceramic, high temperature heat exchanger and maintain optimum air/fuel ratio throughout the combustion air temperature range (ambient to 1,200°F). Supplied a furnace pressure control system to hold a slightly-positive (+.02 w.c.) furnace pressure regardless of changes in furnace pressure that are caused by varying mass flow or by opening of doors. Supplied new high momentum burners positioned to fire directly into the bath or charge. Supplied an all-ceramic exchanger capable of providing combustion air up to 1,200°F and still take flue gas temperatures up to 2,400°F. The exchanger was designed to allow maintenance without furnace shutdown and soot blowing without process interruption. The ceramics were selected to withstand both temperature cycling and acid attack during fluxing. Supplied all the high and low temperature ductwork. This ductwork was arranged and valved in a manner to permit the operators to run the system at full-load capacity with or without the exchanger in service. Each burner has its own fuel, air, and flame safeguard system and can be operated independently. Combustion air temperature is measured at each burner, and the air/fuel ratio, by weight, is held automatically despite changes in the combustion air temperature. The holding burner was not modified to use preheated combustion air.

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