There are various forms of drying equipments. Commonly used in the cement industry includes rotary dryer, flow pattern dryer, stirring drying positive airflow drying tube. In recent years the spray drying devices are still studied at home and abroad. These devices generally use the convection of hot flue gas to dry materials.
Drying operation can go together with crushing operation and powder selecting operation. At present, the coal powder equipments in cement plant make use of the drying and power grinding system. In recent years, using the drying and power grinding system in raw cement becomes more and more at home and abroad. This way can simplify the processing flow and decrease energy consumption. But if the moisture of raw materials is over the limit of drying and powder grinding system, another dryer is needed to preheat the materials. All in all, the drying process is one of the basic heating procedures, and the drying procedure can directly influence the quality of cement. Therefore, great attention must be paid to the drying equipments.
Within the rotary dryer, there are concurrent and counter-flow type according to the differences of the flowing direction of materials and hot gas. The flowing direction of materials and hot gas is same within the concurrent dryer, and in the feeding part, wet materials contact with hot gas, so the drying speed is fast, but in the discharging part, because the materials are easy to be dried and their temperature is raised, and the difference in temperature between them is small, so the drying ratio within the whole cylinder is uneven. However, the flowing direction of materials and hot gas within the counter-flow dryer is reverse, and the dried materials contact with hot gas with high temperature and low moisture, so the drying ratio of the whole cylinder is much even.
Some specific conditions should be considered before choosing from concurrent operation and counter-flow operation: the nature of feeding materials, granularity, the final requirements of moisture, and the arrangement of the workshop. In the cement plant, those two types are all used, but concurrent type takes more positions. ■
Drying Equipment for Cement Plant
There are various forms of drying equipments. Commonly used in the cement industry includes rotary dryer, flow pattern dryer, stirring drying positive airflow drying tube. In recent years the spray drying devices are still studied at home and abroad. These devices generally use the convection of hot flue gas to dry materials.
Drying operation can go together with crushing operation and powder selecting operation. At present, the coal powder equipments in cement plant make use of the drying and power grinding system. In recent years, using the drying and power grinding system in raw cement becomes more and more at home and abroad. This way can simplify the processing flow and decrease energy consumption. But if the moisture of raw materials is over the limit of drying and powder grinding system, another dryer is needed to preheat the materials. All in all, the drying process is one of the basic heating procedures, and the drying procedure can directly influence the quality of cement. Therefore, great attention must be paid to the drying equipments.
Within the rotary dryer, there are concurrent and counter-flow type according to the differences of the flowing direction of materials and hot gas. The flowing direction of materials and hot gas is same within the concurrent dryer, and in the feeding part, wet materials contact with hot gas, so the drying speed is fast, but in the discharging part, because the materials are easy to be dried and their temperature is raised, and the difference in temperature between them is small, so the drying ratio within the whole cylinder is uneven. However, the flowing direction of materials and hot gas within the counter-flow dryer is reverse, and the dried materials contact with hot gas with high temperature and low moisture, so the drying ratio of the whole cylinder is much even.
Some specific conditions should be considered before choosing from concurrent operation and counter-flow operation: the nature of feeding materials, granularity, the final requirements of moisture, and the arrangement of the workshop. In the cement plant, those two types are all used, but concurrent type takes more positions. ■