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How can huixinlong refractory solve the problem of corundum brick peeling caused by slag erosion and loss of castable due to failure and carbonization?

Classification:
News center
Author:
admin
Source:
Zhengzhou huixinlong refractory
Release time:
2020/03/28 09:52
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Howcanhuixinlongrefractorysolvetheproblemofcorundumbrickpeelingcausedbyslagerosionandlossofcastableduetofailureandcarbonization?Toomanytimesofdrivingandparking.Innormalproduction,thetemperatureofthere
How can huixinlong refractory solve the problem of corundum brick peeling caused by slag erosion and loss of castable due to failure and carbonization?
Too many times of driving and parking. In normal production, the temperature of the refractory lining at the furnace mouth is relatively high, while in shutdown (especially when the burner is hung), the temperature of the refractory lining at the furnace mouth drops sharply due to the cooling effect of the cooling coil of the burner (or the entry of a large amount of cold air), and then rises rapidly after the start-up. A start and stop is equivalent to a sudden cold and hot. According to the test results, the corundum brick cracks after 4 times of quenching and heating. From the end of 1983 to the fifth outage in April 1991, two gasifiers were put into operation 195 times and each gasifier was put into operation once in 19.4d. Such frequent start-up and shut-down causes the corundum brick to be frequently quenched and heated, which causes serious damage. In addition, when parking, the furnace is full of water vapor. Due to the cooling effect of the burner cooling coil, condensation water, condensation water, carbon black, slag and other erosion are easy to occur at the furnace mouth, which is easy to cause the peeling off of corundum brick and the loss of castable due to failure and carbonization.
The expansion joint of furnace top is too small. In practice, it is found that the corundum brick and castable with damaged furnace mouth are higher than the flange surface, and the ceramic fiber felt is pressed into flat sheet. This shows that the height of expansion joint of 40mm of the original design furnace top is not enough, and the theoretical calculation also proves that the expansion joint is too small. In this way, the expansion of corundum brick is blocked and subjected to strong pressure, which is easy to damage.
Since January 1988, the improvement measures have been taken for the refractory lining of the gasifier mouth, and gradually improved according to the use effect. After repeated tests, the following measures are taken. The corundum brick at the furnace mouth is changed from three rings to five rings, and the height of single brick at the furnace mouth is changed from 123mm to 70mm, so as to reduce the thermal stress of corundum brick and the possibility of corundum brick cracking; the mortar used for corundum brick at the furnace mouth is changed from alumina mortar with high sintering temperature requirements to the third layer of insulating brick with relatively low sintering temperature, and the joint surface of corundum brick at the furnace mouth and corner brick is changed from The flat surface is changed to the mortise and groove surface to avoid gas channeling from this part.
50 mm high white corundum is poured into the annular gap between the furnace mouth brick and the shell to seal the refractory castable. Stainless steel wire is added to corundum as framework to ensure the overall strength of corundum. The insulating brick shall be built above the corundum to double seal the castable and prevent the castable from running away. According to the expansion coefficient of the corundum brick, the axial expansion of the whole corundum brick lining is calculated, and the appropriate expansion joint height is selected to make the expansion joint height of the furnace top tend to be reasonable, so as to avoid the strong pressure caused by the blocked expansion of the refractory lining.
Since June 1992, the application effect of the refractory lining at the gasifier mouth has been completely improved. The cracking of the brick at the mouth and the running loss of the castable have been basically eliminated, and the over temperature alarm of the outer wall of the mouth has also been eliminated. Improvement measures for refractory lining of combustion chamber from the inspection of refractory lining of gasifier in each overhaul, the reduction amount of corundum brick on the top of gasifier arch and the upper part of cylinder is not large (generally 1030mm, the remaining thickness is 80110 mm), while the corundum brick in the middle and lower part of cylinder is very fast due to the strong erosion of burner flame, and there is little corundum brick left in less than 8000h , not even. For example, in 1989 and 1990, the corundum brick in the lower part of the cylinder was thinned to zero twice, resulting in the collapse of the corundum brick in the upper part and forced to be overhauled in advance. From 1990 to 1991, the reduction rate of corundum brick is about 10 mm per month, which is difficult to guarantee one production cycle.
The main reasons for the damage are as follows. Melting loss. A variety of impurities such as Ni, V, CA, Na, Fe, Mg, etc. in the raw material residue of gasifier react with Al2O3, forming a low melting point compound, which is lost in a molten state at operating temperature. The amount of loss increases with the increase of process operating temperature and process gas flow rate. Spalling. Impurities contained in raw materials of gasifier penetrate into the brick through the opening pores of corundum brick, react with brick components, and generate new minerals. Due to different thermal expansion coefficient or volume change effect (such as V2O3 generates V2O5 when encountering O2, the volume increases by 40%), under the condition of furnace temperature fluctuation, especially the start-up and shutdown, slag cleaning and burner lifting, cracks are generated at the junction of different minerals and expand continuously, and then flake or block peeling occurs. The greater the temperature fluctuation, the more times of starting and stopping, and the more spalling.
Damage by accident. For example, the nozzle is damaged, the cooling water coil of the nozzle is leaking, the nozzle is not installed in the right place, the oxygen is over temperature, the quench ring is damaged, and the quench water overflows into the combustion chamber. The quality of corundum brick and other refractories is poor, the quality of construction and masonry is not qualified, and the quality of baking furnace is poor. At the same time, the refractory lining is improved. The reason for replacing the refractory lining of gasifier is that the corundum brick at the lower part of the combustion chamber is seriously damaged or thinned. At this time, the thickness of corundum brick at the upper part of the cylinder and the vault is still large. Therefore, as long as the thickness of corundum brick at the lower part of the cylinder is increased and the service life of corundum brick at this part is extended, the service life of the refractory lining of gasifier can be extended.
Conclusion through years of efforts, after taking the above improvement measures, the refractory lining of gasifier mouth is easy to be damaged, resulting in overtemperature of furnace mouth outer wall, short service life of corundum brick at the lower part of combustion chamber barrel, overtemperature of thermocouple hole outer wall, etc