| 摘要 |
PROBLEM TO BE SOLVED: To improve heat resistance, corrosion resistance and heat impact resisting properties by forming a ceramic tube for a heat exchanger adapted to recover a heat from an exhaust gas of a melting furnace or the like of a porous ceramic material exhibiting specific values of thermal conductivity and porosity. SOLUTION: A ceramic tube 1 sealing one side surface of a cylinder is projected toward the interior of a gasifying melting furnace from a furnace wall 2, and a pipe 3 is disposed in the tube 1 to constitute the heat exchange. When a melting furnace is operated, the exterior of the tube 1 is exposed with a high temperature combustion gas, and hence when air is sent from the pipe 3, the air can be heated. In this case, the tube 1 is formed of porous ceramics having thermal conductivity of 10 W/m.K or above and porosity of 15% or below. The tube 1 is formed to have a dense SiO2 film on a surface including a crystal phase of SiC, Si3N4 having characteristics of heat resisting impact temperature of 350 deg.C or above by submerging it under water and a flexual strength of 30 MPa or above.
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