Rotary flash dryer, because the air is blown into the heat exchanger by a blower to heat to the required temperature setting value, the heated hot air enters the stirring and pulverizing from the bottom of the rotary flash dryer at an appropriate air flow speed. In the chamber, due to the agitation and the blowing of the hot air, the material is strongly sheared, and the collision friction causes the material to be atomized, thereby strengthening the heat and mass transfer process. The spiral rotating air flow in the drying chamber entrains the material to move upwards. When the larger particles move to the top, the top of the drying chamber is provided with a material classifier. Due to the action of the classifier, the larger particles fall back to the bottom and participate in the above. The movement process is further dried during the ascent. In the drying chamber, the gas-solid two-phase rotation flow, the solid phase inertia is greater than the gas phase, and the relative velocity between the solid-gas two phases is large, which enhances the heat and mass transfer between the two phases. The material enters the diffusion cyclone from the top of the drying tower for material collection. A small part of the tiny dust enters the rotary bag backflushing dust collector with the airflow for collection and recovery, and the hot air is led out by the induced draft fan. In such a working environment, since the spindle shaft seal adopts the wool felt as the process of sealing the main bearing, in the high-temperature operation, the material enters the bearing and is damaged, which has a very serious influence on the working reliability of the rotary flasher. Therefore, the manufacturing process and quality must be given enough attention, and the use of high temperature and friction resistant materials to make mechanical seals to improve their reliability is a simple and feasible method.
First, the reliability problem is raised
Our company has three types of rotary flash dryers, 60, 80 and 85. Among them, 80 type rotary flash dryer speed motor power is 15KW, V-belt drive, working speed 800r/min, reamer diameter 600mm, spindle diameter 95mm, shaft length 1400mm, tower temperature 480°C, installation investment in 2001 After the production and operation, there are more than one month, and less than one week, there is motor over current, main engine vibration, and abnormal noise. It has been repeatedly reported to the manufacturer that the manufacturer can still solve the problem. In July 2002, the same problem occurred again. This time, without the help of the manufacturer, I formed a maintenance team to dismantle the step by step, and studied the damaged bearing of the bearing box. It was designed and manufactured by ourselves. A mechanical seal has successfully solved this problem and the seal has been in operation ever since.
Second, the cause of the failure and process analysis
1, fault surface phenomenon
When I dismantled the failed shaft seal, it was found that the bearing housing entered the material multiple times because the manufacturer opened a wool felt groove in the inner diameter of the bearing gland, and the oil seal accounted for more than 90% of the fault, which was a design defect. The root cause of this led me to study this issue.
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