four de séchage

Les causes et les solutions des fissures sèches saisonnières dans la brique Adobe
La fissuration sèche fait référence au phénomène dans lequel aucune fissure n'est constatée lors de l'essuyage avec du kérosène à l'entrée du four de séchage., mais il y a des fissures et des caractéristiques évidentes d'emplacement sec lors de l'essuyage à la sortie du four de séchage. Le séchage est un processus dynamique, et du point de vue du processus, la qualité du séchage est liée à la stabilité de la logistique, Flux d'énergie, système de transmission, répartition de la chaleur, répartition de la pression, and humidity distribution inside the drying kiln.
The low moisture content of powder in winter and spring (about 6%) is to prevent clumping and poor fluidity of the powder due to low temperature, which affects the uniformity of the fabric. If the high temperature in summer reaches over 40 ℃, the kiln workshop can even reach up to 50 ℃, and the temperature in the raw material workshop is also above 45 ℃. The edge cracks caused by the drying process are related to the strength of the green body (referring to the undeveloped body or the semi dry pressing method, with water content generally ranging from 6% pour 8%) and the strength of the white body (referring to the dried body or the dry body, with water content generally ranging from 0.1% pour 0.25%), as well as the intensity changes of the dynamic process of water discharge and heat introduction. The following opinions are put forward regarding this:
(1) The strength of the adobe is not sufficient. During the transportation of hot powder, moisture will evaporate by 0.2% pour 0.4%; Even for cold powder materials, 0.1% pour 0.25% of moisture will evaporate when transported from the silo to the press platform. Due to the dryness and high temperature in June (with an ambient temperature of 45 ℃ and an outlet temperature of 80 ℃), if the moisture content of the powder material in the drying tower is still controlled at 5.8%~6.0%, the moisture content may only be 5.3%~5.5% when it reaches the press machine. Such low moisture content of the powder material makes it difficult to compact the body, which means that the green strength of the brick body is difficult to achieve a safe transportation state and is prone to cracking.
(2) Pressure fluctuations in the compressor. During the operation of the press, the oil temperature will rise. At high oil temperatures, the hydraulic oil viscosity is low, oil leakage will intensify, sealing will deteriorate, leading to fluctuations in forming pressure and difficulty in ensuring the strength of the brick blank.
(3) La faible teneur en humidité de la poudre entraîne une transmission lente et inégale de la pression dans la presse. La transmission de pression dans la presse est liée à l'évacuation des gaz, conduction de l'eau, et conduction de la poudre comprimée, en particulier, la pression de conduction de l'eau sous forme de liquide est la plus rapide et la plus uniforme. Une faible humidité et une teneur élevée en gaz dans la poudre peuvent ralentir le processus de transmission de pression, exacerber la non-uniformité de la transmission de la pression, and exacerbate the effects of factors such as uneven fabric, mold tolerances, and pressure instability, resulting in uneven structural damage to the stamped bricks. Cracks occur due to stress during drying.
(4) Unreasonable debugging of the drying kiln. En été, the temperature is high, and the hot air blowing in from the bottom of the kiln is affected by factors such as the temperature increase of the kiln combustion air environment and the reduction of heat dissipation in the kiln and pipelines. The temperature of the hot air entering is high, the curve of the kiln head is steep, and the drying speed is faster. If the inlet air volume is reduced without reducing the drainage force, it will cause the constant temperature and drainage zone of the kiln head to disappear, resulting in a decrease in humidity, less inlet air volume, and no decrease in exhaust air volume. À ce point, if the moisture content of the brick entering the kiln is low, the inlet air temperature is high (which may reduce the inlet air), and the suction force at the kiln head does not decrease, it will cause a high negative pressure at the drying kiln head, and the drying system and pressure will be in a state of imbalance.
(5) The billet is relatively fragile during the drying process and requires a stable transmission system. Par conséquent, the transmission of the kiln, especially in the pre drying area, needs to be regularly calibrated, such as gears, single hole aluminum seats, roller bearings, rollers, etc. Especially for sticks, it is necessary to regularly polish the soil powder, rouiller, sulfures, et autres substances collées aux rouleaux. Sur la base de l'analyse ci-dessus, en général, la teneur en humidité de la poudre doit être augmentée entre 6.8% et 7.2% dès que possible. L'accent de l'été devrait être mis sur la conductivité de la pression et l'effet de l'humidité sur la résistance des billettes vertes.. La stabilité dynamique et la stabilité transitionnelle de la pression du four, température, et l'humidité doit être ajustée dès que possible. Un dispositif d'infusion doit être installé en tête du four pour augmenter l'humidité de l'air chaud entrant dans le four.. La pression de déshumidification et de déshumidification doit être ajustée de manière appropriée pour assurer la stabilité uniforme de la pression positive sur la section de température de séchage..