The main reasons for damage caused by the damage caused by the refractory lining of the gasifier furnace are as follows. Thermal stress is too great. Due to the cooling effect of the Texaco burner burner cooling coils, the upper part of the bricks of the burner mouth is kept at a relatively low temperature, while the lower part of the burner bricks is maintained at a relatively high temperature due to the influence of high temperature radiation and high-temperature gas convection in the furnace hearth. . Because of the great temperature difference between the upper and lower ends, it is easy to cause the thermal stress of the furnace brick to crack and crack.
Too many open parking. In the normal production, the temperature of the refractory lining of the furnace is high, and when it is stopped (especially in the case of a burner), the burner is fireproofed by the cooling effect of the burner cooling coil (or the entry of a large amount of cold air). The temperature of the lining dropped sharply and the temperature rose quickly after driving. One stop and one stop is equivalent to one emergency. According to the test results, corundum bricks were cracked by quenching and heating four times. During the period from the end of 1983 to the fifth shutdown in April 1991, two gasifiers opened and stopped 195 times, and each gasifier opened and stopped an average of 19.4d. Such frequent opening and shutting causes the corundum bricks to be frequently quenched, hot and damaged. In addition, when the vehicle is parked, the furnace is filled with water vapor. Due to the cooling effect of the burner cooling coils, condensation water is easily generated at the mouth of the furnace. The erosion of condensed water, carbon black, slag, etc., can easily cause the spalling and pouring of corundum bricks. Material loss due to failure, carbonization.
Top expansion joints are too small. In actual use, it was found that the corundum bricks and castables damaged at the mouth of the furnace were higher than the flange surface, and the ceramic fiber felt was pressed into a flat sheet. This shows that the height of the 40mm expansion joint in the original design was not enough, and theoretical calculations also proved that the expansion joint is too small. In this way, the expansion of the corundum brick is hindered by strong pressure and is easily damaged.
Improvement Measures Since January 1988, improvements have been made to the refractory lining of gasifier furnaces, and improvements have been made gradually based on the effects. After repeated trials, the following more comprehensive measures were taken. The furnace corundum brick was changed from three-ring to five-ring, changing the height of the single block brick from 123mm to 70mm, thereby reducing the thermal stress of the corundum brick and reducing the possibility of cracking of the corundum brick; The mortar is changed from the alumina fired with high sintering temperature to the third thermal insulation brick with a relatively low sintering temperature, and the joint surface between the corundum brick and the corner brick is changed from the plane to the grooved surface. Avoid suffocating from this area.
In the ring gap between the furnace brick and the shell, 50mm high white corundum is poured to seal the refractory castable. Corundum is added with stainless steel wire as skeleton to ensure the overall strength of cast corundum. Above the pouring corundum, the bricks are again built to insulate the castables in a double-enclosed manner to prevent loss of castables. According to the expansion coefficient of the corundum brick used, the axial expansion amount of the entire corundum brick liner is calculated, and the appropriate expansion joint height is selected so that the height of the expansion joint at the top of the furnace tends to be reasonable, so as to prevent the expansion of the refractory lining from being hindered and generate a strong pressure.
Effectiveness Since the beginning of June 1992, the use of the above measures for the refractory lining of the gasifier has been completed. The use of the refractory lining has been fundamentally improved. The cracking of the furnace brick and the loss of the castable have been basically eliminated. The phenomenon of over-temperature alarm at the furnace wall has also been eliminated. The use of combustion chamber lining improvement measures from the perspective of the inspection of the refractory lining of the gasifier, the amount of corundum brick thinning at the top of the gasifier and the upper part of the cylinder body is not large (usually at 1030mm, the remaining thickness at 80110mm ) While the corundum bricks in the middle and lower parts of the barrel are strongly washed by the flame of the burner, the speed of thinning is very fast. There are few or even no corundum bricks that have been used in less than 8000 hours. For example, in the second gasification furnace in 1989 and 1990, the corundum brick in the lower part of the cylinder was reduced to zero, and the upper corundum brick slumped due to the Zibo electric drum, and was forced to make major repairs in advance. The thinning rate of corundum bricks from 1990 to 1991 was as high as about 10 mm per month, making it difficult to guarantee a production cycle.
Causes of damage Caused by the damage of the slag brick gangue brick mainly includes the following points. Loss of melting. The impurities such as Ni, V, Ca, Na, Fe, Mg and other impurities contained in the raw material residue used in the gasifier react with the alumina component Al2O3 to form a low melting point compound, which is lost in the molten state at the operating temperature. Loss increases with process operating temperature and process gas flow rate. Peel off. The impurities contained in the raw material of the gasifier penetrate into the brick through the open pores of the corundum brick, and the rock wool reacts with the brick component to generate new minerals. Due to different thermal expansion coefficients or bulk change effects (eg V2O3 generates O2 to V2O5, the volume increases by 40%), at the junction of different minerals in the case of furnace temperature fluctuations, especially in the case of start and stop, clearance, and hanging burners. Cracks develop and continue to grow, eventually flaking off in flakes or chunks. The greater the temperature fluctuation, the more open and stop times and the more flaking.
Damage caused by accidental events. Such as burner nozzle spout damage, burner cooling water coil leak, burner installation misalignment, peroxygen over-temperature, quench ring damage, chilled water spill into the combustion chamber. The quality of refractories such as corundum bricks is poor, the quality of construction masonry is poor, and the quality of ovens is poor. Improvement measures While improving the above aspects, improvements have been made to the refractory lining. The reason for replacing the refractory lining of the gasifier is that the corundum brick in the lower part of the combustion chamber is damaged or thinned. At this time, the thickness of the corundum brick in the upper part of the cylinder and the top of the arch is still large, so only the fastest increase in melt loss and thinning The thickness of the corundum brick at the lower part of the body extends the service life of the corundum brick at this location and can extend the service life of the entire gasifier refractory lining.
Conclusion After several years of efforts, after adopting the above improvement measures, the refractory lining of the gasifier furnace door is easily damaged, resulting in overheating of the outer wall of the furnace mouth, short service life of the corundum brick in the lower part of the combustion chamber, and easy overheating of the outer wall of the thermocouple hole. The problem was basically solved, and the reduced load production and shutdown maintenance caused by the gasifier was greatly reduced. Through the reasonable deployment of residual oil varieties, optimization of process operations, improvement of lining masonry quality, and quality of corundum bricks produced by Luoyang Refractories Research Institute, the service life of thickened corundum bricks for gasifiers has been met for two years. The need to solve this major problem that has plagued fertilizer production has created favorable conditions for the stable, long-term production of fertilizer plants.
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