Study On ZrO₂-Y₂O₃-CeO₂ Refractory For Ultra High Temperature Carbon Black Furnace

The carbon black reaction furnace is a key device for producing carbon black,which not only affects the efficiency of the carbon black production line,but also determines the type of carbon black produced.Due to the harsh service environment of carbon black furnaces,high operating temperatures,accompanied by high-speed media erosion,slag erosion,and huge temperature fluctuations,strict requirements are put forward for the comprehensive high-temperature performance of the refractory materials used,such as fire resistance,erosion resistance,thermal shock resistance,and so on.The working temperature of ordinary carbon black furnaces is about 1900℃,and the use of aluminum chrome refractory materials can meet its operational requirements.The working temperature of special carbon black furnaces exceeds 2000℃,and aluminum chrome refractory materials cannot meet their operational requirements.Therefore,new materials must be developed.Based on this,this topic prepared ZrO₂-Y₂O₃-CeO₂（abbreviated as ZYC）composite material,studied its hot strength,thermal shock resistance,and corrosion resistance,prepared a high cost performance ZYC-corundum composite material,studied the microstructure of the composite material and its relationship with performance,and simulated the temperature field of a special carbon black furnace using ANSYS software,providing a basis for furnace lining material selection and structural design.The results are as follows:（1）Compared with the ZYC sample,the ZrO₂-Y₂O₃ sample（abbreviated as ZY）with the same amount of additive addition can significantly improve the cold bending strength of the sample.When the amount of Y₂O₃ added is 5 wt.%,the cold bending strength of the sample is 21.0 MPa.Adding an appropriate amount of CeO₂ can significantly improve the density,thermal shock resistance,and high temperature bending strength of the sample.When the amount of CeO₂ is 5 wt.%,the apparent porosity and bulk density of the sample are 23.3%and 4.57 g/cm³,respectively,the high temperature bending strength is 8.6 MPa,and the residual strength retention rate after thermal shock is 69.9%.In addition,the ZY sample added with 5 wt.%Y₂O₃ has many pores and a loose structure,while the ZYC sample added with 5wt.%CeO₂ has fewer pores and a dense structure.The microstructure indicates that compared to Y₂O₃,CeO₂ has a better sintering effect on the sample,which is conducive to improving the density of the material.（2）The corrosion degree of single component Ca O,Al₂O₃,Fe₂O₃,and Si O₂ of carbon black slag on ZYC materials from weak to strong is in the order of Ca O<Al₂O₃<Si O₂<Fe₂O₃.Ca O reacts with ZrO₂ to produce Ca ZrO₃ with low density and high melting point,which produces expansion,promotes densification,and forms a surface protective layer,with little impact on corrosion resistance.Si O₂ reacts with ZrO₂ to produce Zr Si O₄ with low density and low melting point,making the material structure loose and reducing its corrosion resistance.Al₂O₃ does not react with ZrO₂ and has a weak ability to attack the material.Due to its low melting point and extremely low solid solubility with ZrO₂,Fe₂O₃ forms a large number of low viscosity liquid phases at high temperatures,causing severe penetration and erosion of the material.The research of erosion test shows that the Xinjiang oilfield slag with the main components of Ca O and Al₂O₃ has weak erosion damage to the material,because the slag reacts with ZYC to generate Ca ZrO₃ and CA6,forming a dense protective film on the surface of the material,which inhibits the penetration of the slag.Daqing oilfield slag,mainly composed of Fe₂O₃,has serious erosion damage to materials.Due to the high content of Fe₂O₃in the slag,the melting point and viscosity of the slag are significantly reduced,increasing the damage caused by penetration erosion of the slag to materials.（3）The effect of composition on the properties of ZYC-corundum composite was studied.With the increase of the amount of aluminum based raw materials added,the strength of the composite decreased,and the thermal shock resistance first increased and then decreased.When the amount of ZYC raw materials added was 62.5 wt.%,and the amount of aluminum based raw materials added was 37.5 wt.%,the flexural strength at room temperature was 10.3MPa,the flexural strength at high temperature was 7.9 MPa,and the strength retention rate after thermal shock was 73.8%.At this time,the composite surface structure was relatively stable,It can meet the use requirements of carbon black furnaces.The effect of composite structure on the properties of ZYC-corundum composite was studied.As the composite structure became more complex,the composite interface area increased,and the strength and thermal shock resistance of the composite increased.However,when the composite area ratio was greater than 1.5,the reinforcement effect slowed down.Therefore,when the composite area ratio is 1.5,the material performance is good and the composite structure is simple.（4）The temperature fields of carbon black furnaces with different systems at operating temperatures of 2100℃,2200℃,and 2300℃were simulated.For the current system,the use of alumina bubble refractory castables for the insulation layer cannot meet the normal operation.After the insulation layer material is changed to zirconia bubble refractory castables,from the simulation results before and after erosion and wear,the hot end temperature of zirconia bubble refractory castables for the insulation layer is lower than 1850℃,and the furnace shell temperature is lower than 270℃,indicating that the furnace can operate normally.For the new system,through simulation,when the furnace lining structure is sequentially made of ZYC material with a thickness of 40 mm（CeO₂ addition amount of 5 wt.%）,ZYC-corundum composite product with a thickness of 74 mm（aluminum based raw material content of 37.5 wt.%）,zirconia bubble refractory castable with a thickness of 80 mm,alumina bubble refractory castable with a thickness of 170 mm,and high aluminum refractory fiber board with a thickness of 20 mm,The hot end temperature of each layer interface is lower than the maximum service temperature of the selected material,which can meet the long-term use requirements of 2300℃.