Improve the service life of chrome corundum bricks for gasifiers
The main factors influencing the service life of chrome corundum bricks include gasifier load, operating temperature, coal ash melting point, ash content, and gasifier type.
The service life of the chrome corundum brick (also known as the high chrome brick) of the gasifier body and the top of the arch is generally 8000~20000h, and the service life of the slag mouth and the conical bottom high chrome brick is generally 3000~6000h. The service life of each part is Mismatches greatly affect the overall service life of the gasifier and the rhythm of the entire production, and increase operating costs. Therefore, it is of great significance to carry out relevant research and further increase the service life of high-chromium bricks. To this end, the following studies have been conducted mainly at home and abroad:
(1) Improve the content of Cr2O3 in the material and optimize its resistance to slag erosion. Due to the excellent resistance to slag corrosion and resistance to slag permeation of Cr2O3 materials, increasing the content of Cr2O3 in chrome corundum bricks can effectively increase the service life of chrome corundum bricks; however, excessive Cr2O3 content will affect the sintering of products and reduce the high chrome bricks. Strength and thermal shock resistance. Therefore, while increasing the content of Cr2O3 in high-chromium bricks, attention must be paid to the problem of reduced strength and thermal shock resistance.
(2) Improve the density of high chrome bricks and reduce the apparent porosity of brick surfaces. Improve the density of high chrome bricks, or use salt immersion, surface coating and other measures to fill the pores on the surface of high chrome bricks, can effectively prevent the infiltration of slag, and increase the service life of high chrome bricks.
(3) Improve the strength of high chrome bricks and increase their resistance to erosion. High-chromium bricks are subjected to strong scouring of high velocity air currents and entrained slag during use, and the brick's resistance to erosion and abrasion is directly related to its strength. The purpose of improving the strength of high chrome bricks can be achieved by optimizing the product particle size distribution, increasing the firing temperature of the product, and adding new binders and accelerants.
(4) Use phase transformation toughening to improve the thermal shock resistance of high chrome bricks. High-chromium bricks have poor thermal shock resistance, and are prone to thermal shock cracks in gasifier ovens, feeding, and actual operation, thereby accelerating the percolation of coal slag. By using the volume effect of 3%~5% of the phase transition from tetragonal ZrO2 to monoclinic ZrO2, an appropriate amount of micro-cracks around the ZrO2 particles can be generated, which can buffer the thermal stress generated within the product due to temperature changes and improve the thermal shock resistance of the product. .
(5) According to the difference of the rate of fire brick erosion and the dominant damage mechanism in different parts of the gasifier, certain properties of the refractory bricks in some parts can be targetedly improved, and the integrated bricklaying technology is adopted to extend the gasification furnace refractories. The overall service life.
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