In order to understand the failure mechanism of magnesia-alumina spinel crown of glass melters,a discussion on the stability of Mg-Al-spinel crown of glass melters was given in this paper.The discussion focused on the...In order to understand the failure mechanism of magnesia-alumina spinel crown of glass melters,a discussion on the stability of Mg-Al-spinel crown of glass melters was given in this paper.The discussion focused on the weight balance in the crown arch made of spinel or silica bricks,the creep of spinel crown bricks at high temperatures,the thermal stress distribution in crown bricks as well as at brick joints,and the displacement behavior of crown arch during heat-up of glass melter.It is believed that the tangential stress in spinel crown is much higher than that in silica crown due to the large differenee in their densities,and that the thermal stresses in the crown brick result in opening of a part of the brickto-brick joints at the cold side of the crown,and increase of the tangential stress needed for balancing the weight of the crown.Both defect migration in lattice or along grain boundary and viscous flow in glass phase at grain boundary contribute to the creep of crown bricks at high temperatures.The creep of the matrix of spinel brick is more significant than that of coarse grains because impurities,such as silica and calcia,are concentrated in it.For keeping the crown stable during heat-up period it is important to adjust properly the horizontal positions of each skew brick as temperature increasing based on correctly evaluating the thermal expansion according to the thermal expansion coefficient of the crown brick.展开更多
Flow behavior was observed in a simplified model cavity of a multiphase High Level Liquid Waste (HLLW) reprocessing glass melter. Electrodes were set to generate Joule-heating flow in the cavity. A chaotic flow occurr...Flow behavior was observed in a simplified model cavity of a multiphase High Level Liquid Waste (HLLW) reprocessing glass melter. Electrodes were set to generate Joule-heating flow in the cavity. A chaotic flow occurred because the lower part of the cavity was heated while the top surface of the cavity was cooled. Downflow and upflow occurred alternately in cavities. The shape of the cavity was a sloping bottom cavity, which was similar in shape to the real glass melter. To know the flow behavior in the cavity, 1-D flow behavior and 2-D flow behavior were measured in an experiment and simulated by an original CFD code. In the sloping bottom cavity, chaotic flow occurred in the upper part of the cavity. In the case of the sloping bottom cavity which had the same set of electrodes as the glass melter, the effect of the downflow near the electrodes decreased. The same phenomena could be predicted in the melter. The experimental results were also used to validate the CFD code, which will be helpful for developing a multiphase Joule-heating flow predicting.展开更多
For the melting process in E-glass unit melter, the natural convection of the glass molten was weakened by the narrow body and high viscosity. Therefor bubbling in molten will become a necessary process of the melting...For the melting process in E-glass unit melter, the natural convection of the glass molten was weakened by the narrow body and high viscosity. Therefor bubbling in molten will become a necessary process of the melting. Comparing with the bubbling in water and in liquid metals, the bubbling and bubble formation in the condition of high viscosity molten shows very special. It could be proved that the bubble size in glass molten mainly depend on the viscosity and the flow rate of air.展开更多
文摘In order to understand the failure mechanism of magnesia-alumina spinel crown of glass melters,a discussion on the stability of Mg-Al-spinel crown of glass melters was given in this paper.The discussion focused on the weight balance in the crown arch made of spinel or silica bricks,the creep of spinel crown bricks at high temperatures,the thermal stress distribution in crown bricks as well as at brick joints,and the displacement behavior of crown arch during heat-up of glass melter.It is believed that the tangential stress in spinel crown is much higher than that in silica crown due to the large differenee in their densities,and that the thermal stresses in the crown brick result in opening of a part of the brickto-brick joints at the cold side of the crown,and increase of the tangential stress needed for balancing the weight of the crown.Both defect migration in lattice or along grain boundary and viscous flow in glass phase at grain boundary contribute to the creep of crown bricks at high temperatures.The creep of the matrix of spinel brick is more significant than that of coarse grains because impurities,such as silica and calcia,are concentrated in it.For keeping the crown stable during heat-up period it is important to adjust properly the horizontal positions of each skew brick as temperature increasing based on correctly evaluating the thermal expansion according to the thermal expansion coefficient of the crown brick.
文摘Flow behavior was observed in a simplified model cavity of a multiphase High Level Liquid Waste (HLLW) reprocessing glass melter. Electrodes were set to generate Joule-heating flow in the cavity. A chaotic flow occurred because the lower part of the cavity was heated while the top surface of the cavity was cooled. Downflow and upflow occurred alternately in cavities. The shape of the cavity was a sloping bottom cavity, which was similar in shape to the real glass melter. To know the flow behavior in the cavity, 1-D flow behavior and 2-D flow behavior were measured in an experiment and simulated by an original CFD code. In the sloping bottom cavity, chaotic flow occurred in the upper part of the cavity. In the case of the sloping bottom cavity which had the same set of electrodes as the glass melter, the effect of the downflow near the electrodes decreased. The same phenomena could be predicted in the melter. The experimental results were also used to validate the CFD code, which will be helpful for developing a multiphase Joule-heating flow predicting.
文摘For the melting process in E-glass unit melter, the natural convection of the glass molten was weakened by the narrow body and high viscosity. Therefor bubbling in molten will become a necessary process of the melting. Comparing with the bubbling in water and in liquid metals, the bubbling and bubble formation in the condition of high viscosity molten shows very special. It could be proved that the bubble size in glass molten mainly depend on the viscosity and the flow rate of air.
