In the incinerator combustion chamber, since the temperature is higher than 1000 °C, the input of waste will inevitably cause temperature change. Therefore, the refractory material is required to be not only wear-resistant, corrosion-resistant, difficult to adhere, but also resistant to alkali and oxidation. The lower side wall of the grate is also subjected to the effects of garbage wear and slag adhesion.
Therefore, the damage of the furnace wall of the grate furnace is concentrated in the refractory material of the front and rear arch areas and the refractory bricks of the second and third stages of the side wall of the grate, especially the furnace wall with air-cooling structure is prone to bulging "bullet bag" phenomenon, even collapses in severe cases. . Through the analysis of the damage of these key parts, and provide relevant countermeasures, for reference only.
Refractory erosion ash in front and rear arch areas
Due to the high temperature, the front and rear arch areas are in direct contact with high-temperature flue gas and fly ash, resulting in serious erosion of refractory materials, serious adhesion of ash and even falling off. Figure 1 is a photograph of a Siggs 500t incinerator in Suzhou after 1 year. According to the analysis results of the residual lining, the reaction between the ash and the bulk material is obvious. The formation and erosion of a large amount of low-melt is caused by the burning of the steel in the back arch zone. The main reason for forced shutdown.
At present, most of the refractory lining materials used in the front and rear arch regions are corundum mullite or mullite oxide materials with fire resistance, wear resistance, thermal shock resistance and strong scouring resistance, which are oxidized in an incinerator atmosphere. The material is easy to react with garbage fly ash, etc., and erodes and infiltrates, resulting in ash adhesion. Therefore, it is necessary to stop the furnace ash during the operation of the lining of the incinerator. Compared with oxide materials, non-oxide materials such as silicon carbide not only have good fire resistance, high hardness and good thermal shock resistance, but also silicon carbide materials are not easy to wet and have good corrosion resistance. Therefore, they have good properties. Anti-ash slag erosion and adhesion, largely solve the problem of garbage fly ash adhesion. The developed corundum-silicon carbide and silicon carbide materials are shown in Table 1. They are widely used in the first channel and the oblique top of the incinerator. As shown in Figures 2 and 3, the effect is good.
Figure 2 The first channel water wall tube lining
Figure 3 Water-cooled inclined roof with silicon carbide lining
The microstructure of the sample after the ash slag erosion test was analyzed. The results in Figure 4 show that the reaction interface between the ash and slag containing no silicon carbide and the bulk material is not clear, and the erosion and penetration are severe, while the silicon carbide-containing material and ash are contained. The reaction interface is clear, the ash residue is difficult to corrode the bulk material, and it is not easy to adhere; and as the silicon carbide content increases, the interface is more obvious, and the material is more resistant to ash slag corrosion.
Air-cooled furnace wall "drum bag"
The Higgs grate or Martin grate uses air-cooled furnace walls on the side walls of the second, third and fourth grate, generally with 60mm air interlayer, and the working layer refractory bricks are 114mm (Higgs) and 176mm (card) Vantaa) refractory bricks. In the process of using such a structural furnace wall, the thermal stress caused by the fluctuation of the temperature difference in the furnace caused by the fluctuation of the humidity or the heating value of the furnace, and the structural stress caused by the repeated stop and the furnace operation are both likely to cause the high temperature section of the furnace wall. The stress is concentrated and “bulk-packedâ€, and in severe cases, it falls off or collapses.
Figure 4 is a photograph of the maintenance of a furnace grate in Shenzhen after 1 year of use. The air interlayer is widened from the original design of 60mm to more than 100mm, and the ash residue on the material working surface is seriously attached. The investigation found that there was a “drum kit†in the furnace wall. In addition to the fluctuation of the temperature difference in the furnace caused by fluctuations in the humidity or heat value of the garbage and the reasons for repeated shutdown and furnace operation, the currently applied air-cooled furnace wall design is in the 4-wall structural unit of the side wall ( 1880mm wide) There is a problem of insufficient pulling force. The number of anchor bricks in the structural unit with 4 layers can be increased. Especially, the hook bricks are added at the climbing point of the incinerator and the connection between the furnace walls of different grate sections, which is beneficial to improve the unit. The strength of the pull. In addition, the strength of the hook brick does not meet the requirements, the metal parts of the hook brick are not well-fitted, and the level of the wall of the furnace wall is poor, which also greatly affects the structural stability of the side wall, and needs to strengthen product production and on-site construction. Control.
in conclusion
Due to the high temperature of the front and rear arches, it is seriously eroded, infiltrated and washed by the flue gas and dust ash. The use of silicon carbide-containing materials can greatly improve the ash-resisting corrosion penetration of the lining and the anti-adhesion of ash. In addition, the anchoring brick design can be used to increase the tensile strength of the unit structure, which can alleviate the problem of the drum wall "bullet bag" to some extent. In addition, improving the strength of the hook brick, the quality of the metal parts of the hook brick and the installation quality, and the level of the wall of the furnace wall also greatly improve the structural stability of the side wall.
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