Abstract:
The objective of this research is to study potential for utilizing waste heat from 5 industrial furnaces; indirect fired kiln, shuttle kiln, reheating furnace, glass melting furnace and roller tunnel kiln. Studies were carried out on the control of excess air to standard values. The results of this measure can lead to fuel saving of 279 liters, 113 kg, 8,434 liters and 58,187 liters per year for the 4 furnaces respectively.The use of waste heat recovery system to transfer heat from the flue gases to the combustion air give the potential heat transfer values of 53.98 MJ/hr, 81.53 MJ/hr, 3,598 MJ/hr, 5,645 MJ/hr and 42.12 MJ/hr respectively. In comparison with the useful energy in flue gases the amount of heat recovered would be 29.59% , 80.47% , 46.33% , 63.93% and 42.30% respectively. It follows that 3.31% , 20.63% , 17.40% , 28.75% and 3.22% of fuel consumption respectively could be saved by using the waste heat recovery system. This amount of saving was found to be equivalent to 102.81 liters, 7,881.6 kg, 259,476 liters, 976,912 liters and 8,517.44 MMBTU per year respectively with corresponding, saveing of 41,298 baht, 102,460 baht, 102,460 baht, 3,287,566 baht, 12,377,487 baht and 1,362,790 baht per year respectively.After the recuperator had been used to preheat the combustion air to the industrial furnace, the system effectiveness was found to be 0.3.86, 0.8332, 0.5462, 0.76658 and 0.4518 respectively. The cost of investment of the recuperator for reheating furnace, glass melting furnace and roller tunnel kiln is 3,000,000 baht, 6,000,000 baht and 2,500,000 baht with a simple payback of 11 months, 6 months and 1.83 year respectively.