EXAMPLES OF CONDENSATION INTRODUCTION IN CEMENT PLANT
1.1 Examples of high temperature
A factory φ 4.5m × l2.96m cement mill with a cyclone separator flow grinding circle, using the flat end mill baghouse dust. Exposure to indoor mill system, the mill, and the outside air convection is weak, low system air leakage, the exhaust gas treatment system is not external insulation. Production was found: a large bag filter pressure drop; the grinding of cement temperature up to 150 ℃ productions has been maintained by regularly changing the filter bag.
1.2 Examples of low temperature
B factory φ 3m × lm same as the cement mill with a cyclone separator flow grinding circle, using the airbox bag filter. Purchased clinker, clinker grinding into winter with air temperature considerably, while the summer is slightly higher 15 ℃, mill waste gas treatment system without external insulation. Mills for the semi-open, indoor and outdoor temperature the same. Normal operation, exhaust emissions to a minimum temperature of 18 ℃. Check the mill run top of the bag filter housing, found that the chamber housing temperature with atmospheric temperature has been quite open gas tank cover, clean air chamber walls many see the water, cover the backside into a wet; localized filter almost filled between wet cement dust bags; a bag of cement due to the cleaning out of extremely difficult hard knot; out of the bag after the bag was found the whole look both wet ash covering as syrup or hard knot state, mostly hard- bottom bags housing; housing near the bag due to low temperature, condensation blockage is more serious, especially in the corners more serious.
2.1 Analysis
Stop grinding starts when there is any heat, residual moisture continues to evaporate, while the exhaust fan is stopped, the air volume is very low, so it is easy to make it condensation. After cooling down the whole system, bag filter at the rearmost position, the heat capacity is not itself. Many plants use airbag filter box is a relatively bulky, more cooling area, plus had the lowest temperature cooling fast, easy to reach the dew point. In addition, the bag airflow tiny water droplets (mist) with full filtering “intercept” the role of the water in this concentrated precipitate; if the case from the feed line to the ventilator interlock jump stop or stop feeding time without water early insufficient amount of exhaust fan shut down prematurely, the mill more water than normal stop grinding; or spray atomization bad, the water evaporates behind, dew will have intensified. Especially in the winter, cooling fast, big drop, below the dew point precipitated water. Effect of cooling condensation stop grinding into the ground by the total amount of water, ventilation, temperature rough calculation rough estimates, but more difficult to achieve a detailed and accurate, because the amount of water evaporated lag is difficult to determine, can only get experience accumulated by the operating essentials. To sum up, the negative effects, stop grinding bring even low-temperature exhaust gas type also exist.
2.2 mill ventilation
The mill grinding operating parameters of ventilation is a very important process. A grinding mill has its best within the range of ventilation under certain conditions and the best wind range values considerable differences. The mill by exhaust ventilation exhaust fan to maintain. Due to the former mill after ventilator along with a series of air leakage points, each point relaxes a little air leakage sealing, the mill ventilation will be greatly affected.
3.Solution
1 ) Regular inspection material into the mill’s total moisture. Pay close attention to the clinker, limestone, gypsum, and other materials in the mill rain moisture. Pay attention to the weather brings.
2 ) Appropriate to increase mill ventilation and explore the best wind range. The negative pressure grinding operation will be seized items included in the inspection.
3 ) Air cleaning filter bag pressure is maintained at 0. 5MPa or more, requires water separator, airbag to promptly turn on the water.
4 ) Check out leakage of exhaust gas treatment system regularly, the implementation of a comprehensive plugging of the mill exhaust system necessary external insulation.
5 ) Cryogenic grinding season cold boot, try to avoid an excessive temperature rise of the material into the groundwater. Pay attention to controlling the feed rate; a circle flow flour mill can increase the amount of promotion back to the mill air temperature.
6 ) Ensure good atomization with the watermill. Stop grinding before a quarter of an hour in advance without water. Avoid water evaporation lagged adverse effects on the bag.
7 ) Recommend the use of polyester material after polyethylene bag water and oil treatment
