Regen Regenerative Burner for High Performance, Heat Recovery in Aggressive Environments

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The furnace takes about 4 hours to recover to control after charging, and a temperature spread of better than 10°C (20°F) is reached within a further 4 hour soak per i od. No abnorma I sca ling or other metallurgical problems have been encoun­tered with the reGen System. The chart section (Figure 10) shows the con­t i nuous record of furnace temperature, air preheat temperature and regenerator exhaust temperature. The air preheat is measured by thermocouples mounted in the burner neck, the waste gas temperature by thermocouples in the regenerator outlet connection. The chart was runn i ng at a speed that does not i dent i fy the temperature swings on reversal clearly but they can be seen dur ing the "recovery" port ion noted on the record. -APPLICATION- 4 TONNE/H ALUMINUM MELTING FURNACE ALUMINUM CORP. LTD., DOLGARROG, U.K. DATE OF INSTALLATION - January 1985. EQUIP~ENT - One 8 GJ/h (8 million BTU/hr) gas fired unit comprising two burners, two regenerators and associated controls. DESCRIPTION - The 12 tonne (13.2 ton) capaci­ty furnace is of round, top charged, configura­tion with swing away roof. Originally heavy oil fired since its installation in 1979, it was converted to gas and given a major renovation at the end of 1984. At that time, the furnace was completely relined with phosphate bonded plastic to the metal line and brick for the side walls and roof. The 8 GJ/h (8 mi II ion BTU/hr) reGen unit was then installed and used to dry out and cure the new refractory of the furnace. The furnace is charged with 10% ingot, 90% scrap (composed of swarf and I ight/medium produc­tion scrap) from clamshell buckets. Temperature control for the 6 to 8 hour furnace cycle is by roof thermocouple during melting, switching to a bath thermocouple when "flat bath" conditions have been reached. A nitrogen bubbling lance is used for cleaning, degassing and stirring purposes. 83 Flux is used for skimming and furnace cleaning. PERFORMANCE - Despite the high level of waste gas contamination, the reGen system has been operating fault-free with a two weekly cleaning of the two regenerators. Cleaning is a simple operation taking about 1 hour total from start to finish. Once the packing is drained and cooled the water soluble carryover is removed by tumble washing. The packing is then replaced in the regenerator housing. The reGen System is providing a 39% fuel reduction, a specific fuel consumption of 3.70 GJ/t (1590 BTU/lb) compared with the 6.02 GJ/t (2590 BTU/lb) of the previous heavy oil opera­tion, giving a straight-line payback period of less than 9 months. -APPLICATION- 2 TONNE/H ALUMINUM MELTING FURNACE ALCAN ENFIELD ALLOYS LTD., BRADFORD, U.K. DATE OF INSTALLATION - March 1985. EQUIPMENT - One 8 GJ/h (8 million BTU/hr) gas fired unit comprising two burners, two regenera­tors and assoc iated contro Is. DESCR I PT ION - The furnace is a 41 tonne (90,000 Ib) capacity secondary smelter, melting the full range of scrap aluminum into casting alloys and "hardeners". Alcan operates the furnace as a batch melter with a 40 hr tap to tap cycle (charging, melting, refining and tapping). Potassium Aluminum Fluoride is used for daragging. The scrap charged is very dirty, conta in i ng pa i nt, varn ish, pi ast ic and other contam i nants. PERFORMANCE - This installation is achieving a fuel saving of 37% and a melt rate increase of 5% over previous operation. Cleaning of the regenerator packing is required once every week because of the high level of exhaust contamination. In this case the dry carryover is being removed from the packing by sieving.