High temperature regenerator design for industrial furnace applications

An experimental study has been performed to derive design guidelines of regenerator for high temperature air preheating. Cylindrical ceramic honeycombs were used for regenerator because of their larger surface area, lighter weight and lower pressure loss than ceramic balls. Two kinds of material (50% cordierite+50% mullite and 100% cordierite) were used in the fabrication of honeycombs. Experiments were carried out with varying combustion load (23-60kW), air ratio (1.05-1.5), firing time 10-90second), honeycomb cell density (100cell-300cell) and honeycomb regenerator length (100-300mm). Temperature efficiencies were calculated using the temperatures at the inlet and outlet of the regenerator while maintaining the average furnace temperature at 1,200 degreesC. It was shown that the temperature efficiency decreases with increasing firing time and combustion load for a given cell density and length of the regenerator. The decreasing rate was varied depending on the regenerator material. A concept based on the number of passages of exhaust gas through the regenerator was suggested by normalizing the firing time with operating conditions. The variation of temperature efficiency was correlated well with the number of passages introduced in this study. The maximum number of passages for obtaining a temperature efficiency of higher than 90% was 1,000.