The effect of fused and sintered mullite on properties of ceramic heat shield in V94.2 gas turbines

摘要

V94.2 single shaft, double combustion chamber is heavy duty gas turbine with capacity 159MW and efficiency 34.9%. Each combustion chamber consists of 8 burners. Temperature of combustion productions leaving combustion chamber and interring gas turbine is around 1060 °C. To protect combustion chamber inner wall from overheating, inner wall is shielded by ceramic tiles. In this research mullite and tabular alumina is mixed with certain ratio and fraction adding nano silica solution and necessary additives [1]. The tiles are sintered for 10 hr at the temperature 1550°C after forming and freezing -75°C using the mixture mention about. The physical, mechanical, and thermo mechanical properties of samples such as bulk density, open porosity, bending strength at room and high temperature, elastic modulus, thermal expansion and conductivity were investigated in Wuhan institute in China which is a member of ILAC. The results showed that the type of mullite has significant effects on the properties of samples. Modulus of rupture at room temperature, 1200 C and 1400 C were 9.91 MPa, 10.83 MPa and 6.85 MPa for fused mullite containing sample but for sintered mullite containing sample these value were 8.72, 9.35 MPa and 5.31 MPa respectively. The thermal shock resistance of two samples after 30 cycles from 1000 °C to cold water showed that number and size of cracks in the fused mullite containing samples were lower than from sintered mullite containing sample. These results related to the shape of acicular mullite grain of fused mullite.