Properties of clay refractory

(1) Fire resistance. The low degree of fire resistance of clay refractory products is lower, and the increase of three aluminum oxide content in clay brick is improved… Generally 1580 for ~1750;

(2) Load softening temperature. Fireclay refractory load softening temperature is low; refractoriness under load was usually less than 1300 degrees.

(3) Thermal shock stability. Fireclay refractory thermal shock stability is better, the main reason is mullite crystals are surrounded by glass phase, mullite itself smaller coefficient of expansion, when heated does not produce stress concentration, so the stability of thermal shock resistance is good.

The main factors that affect the thermal shock stability of clay refractory are the physical properties of raw materials and the structure of clay brick… Therefore, the thermal stability of the clay brick can be improved by increasing the proportion of clinker and adopting reasonable brick making process…

(4) Slag resistance. The main chemical constituents of the clay refractory are silica and threealumina, and the former is more than the latter, and the clay brick is obviously weak acidity… Therefore, the ability of acid slag erosion ability than the strong anti alkaline slag.

Increase the density of two aluminum oxide and clay brick, increase the content of clinker, decrease porosity and decrease the impurity content of clay brick, and increase slag resistance of clay brick…

(5) The change of heavy firing line. For the clay refractory, the shrinkage of the residual shrinkage is no more than l%. Increasing tile clinker proportion, an appropriate increase in firing temperature and reasonable insulation, can make clay brick volume stability improvement, that reheating linear change decreases.

Why coke oven must use silica bricks

Silica brick belongs to acidic refractory  material, has good acid resistance erosion ability, its good thermal conductivity, high refractoriness under load, general in 1620 DEG C above, only than the low refractoriness of 70 to 80 DEG C. Brick thermal conductivity increases with theincrease of temperature, no residual shrinkage, in the baking process, the volume of the brick with the increase of temperature increases. Therefore, silica is coke oven ideal refractory products, modern large and medium coke important parts (such as the combustion chamber, ramps and regenerator with brick masonry.

In the baking process, silica brick maximum expansion occurred in the 100 to 300 DEG C, 300 DEG C before the expansion is about 70% to 75% of the total amount of expansion. The reason is SiO2 in baking process appear 117 degrees, 163 DEG, 180 to 270 DEG C and 573 DEG C four crystal transition points, including 180 to 270 DEG C, caused by cristobalite volume maximum swelling.

Thermal stability of silica brick quality is the key to true density and the size of the true density is to determine the important symbol of the transformation of the quartz. The true density ofsilicon is smaller, the lime into more completely and the residual in the oven in the process of expansion is small.

In the brick, tridymite crystal true density minimum and linear expansion rate, good thermal stability such as quartz and quartz, slag corrosion resistance strong, good thermal conductivity, high refractoriness under load is quartz volume is the most stable form. Burnt better silica brick, tridymite content was the highest, accounting for 50% ~ 80%; cristobalite times accounted for only 10% ~ 30%; and quartz and glass phase content fluctuation in 5% ~ 15%.

When the working temperature is lower than 600 DEG C, brick volume changes larger, anti sudden cold and hot performance is poor, the thermal stability is not good. If the coke oven is working at this temperature, the masonry is easily cracked and damaged…

Refractories for heat exchange furnaces

The heat exchanger is an important part of the center of bottom burner furnace, four corners burner soaking pit and one sided upper burner soaking pit for the preheating of the air or gas. The first two stove of heat exchanger is arranged in the stove on both sides of the wall outside, after a set the end wall burner in an external, are located in the flue and the exhaust vent and furnace stare Unicom.

The lining of heat exchanger is made of clay brick, and its brick type has four holes of clay brick, circular or star shaped clay or clay brick, etc… The characteristic is that the preheating temperature of air and gas is high, but the air leakage rate is big, and the service life is about 1 year… When high alumina silicon carbide refractory cast material, the centrifugal method is used to form round pipe brick, the length of 2m is above, and the leakage rate is reduced, the service life is increased by 50%…