Because the calorific value of producer gas is not high, mostly between 5230~5648kj/m3 (1250~1350kcal/m3), the gas must be preheated to reach 750℃ or even higher to meet the glass melting temperature Claim. When the coal gas passes through the gas regenerator, the environment of the gas regenerator on this side is a strong reducing atmosphere, and the other side is the flue gas passing through, presenting an oxidizing atmosphere. If there are some variable valence elements in the refractory material, its valence state will change with the change of the oxidation-reduction atmosphere, and with the change of the valence state accompanied by a large volume change material, the oxidation-reduction reaction causes the brick body to expand and contract , Long-term exposure to this oxidation-reduction reaction atmosphere will cause the bricks to break and disintegrate.
Due to the periodic temperature changes in the horseshoe flame kiln, it needs to be switched every 20~30min. When passing the flue gas, the tongue hanger bears the scouring of the high temperature flue gas of about 1400℃. The gas passes through the gas, and the temperature of the tongue hanging is between 750 and 1150℃. There is a large temperature difference between the front and back tongue hangings. The temperature difference is affected by the temperature of the gas itself (the temperature of the gas outlet, the length of the gas pipe, the change in the heat dissipation and heat preservation of the gas pipe), and the temperature reached by the gas after the grid body is preheated (affected by the size and height of the gas regenerator) , There is a certain degree of thermal shock, so the regenerator materials such as tongue clasps are required to have good thermal shock resistance; especially due to the failure of gas generators, gas exchangers and other abnormal factors, the regenerator cannot be replaced in time When changing direction, the material of the regenerator such as tongue stubs bears greater thermal shock, because the temperature difference between the front and back is greater. It is specially stated here that if the above special circumstances occur, the direction should be restored as soon as possible, and the time of each change should be short. After each commutation, the commutation time is gradually increased and finally restored to the normal commutation time.
Due to the influence of the sulfide content in coal, the concentration of sulfide, sulfate, and sulfite in coal gas is much greater than that in flue gas. The choice of refractory material is very important, so it also seriously affects the life of the kiln.
Fused cast AZS brick has good corrosion resistance, high refractoriness, load softening, and good mechanical strength. It should be a very good material. However, 33# fused cast AZS brick has a crystal form transition from α to β around 980~1180℃, and there is a large volume change. If the gas outlet temperature is low and the height of the grid body of the gas regenerator is not high, the gas cannot be higher than 1180℃ after preheating, and avoid the crystal transformation temperature of the fused cast AZS brick, then the fused cast AZS brick is used as the material of the tongue. inappropriate. Because every time the direction is changed, the tongue sling will expand and contract, and the fused AZS brick will burst after a longer time, and the fused cast AZS brick will fall down in large pieces, which will eventually cause the tongue to collapse and affect the life of the kiln.
Although mullite bricks or triple-resistance bricks and other products have good thermal shock resistance, thermal shock resistance, and corrosion resistance, they have low creep resistance and uneven quality control by manufacturers. The phenomenon of peeling and collapse often occurs in the medium.
We have used siliceous materials as the material for the tongue splint, but the siliceous material has poor alkali resistance. Alkaline substances in the flue gas pass through the tongue splint in a gaseous state. When the alkaline substance is in a liquid state, it will corrode acidic materials more. Time is much milder. The practice of many kilns has proved that although the front end of the siliceous material as a tongue chute is corroded, there is no problem in 4 to 5 years. After the kiln has been used for a few years, the front end of the tongue chute is corroded, and the premixing section is only lengthened at this time. However, due to various reasons, the energy consumption will increase and the gas volume will increase, so the length of the flame is less affected. Although siliceous materials have multiple crystal transformations below 600°C, their expansion coefficient is relatively large. It is relatively stable above 600℃, and the creep temperature is very high, which can meet the temperature requirements. Therefore, we plan to use calcium-free silica bricks or zero-expansion silica bricks as the material of the tongue.
