Failure analysis of spray dryers

Even the most successful design is guaranteed to be trouble-free during operation, even with climatic and seasonal variations, so many factors are variable in operation. As an experienced operator, when an abnormality occurs in the system, the cause should be found in the shortest possible time, so that the problem can be solved as soon as possible. Failure in the system does not matter how big or small, as long as you can not find out in time are big failures, in the production of faults that often occur are mainly the following points:

1, the sticky wall of the material

   In the production of the phenomenon of sudden sticking wall, mainly due to changes in operating parameters are not coordinated, may be related to the following factors: A change in air volume B adjust the air volume of the fan may lead to changes in air flow C atomisation effect caused by poor sticking wall with the above clues, from which point of view to find out the cause is clearer!

2、Product moisture exceeds the standard

   Product moisture exceeds the standard is mainly related to the wind speed and temperature, in addition, the relative humidity of the ambient air is also one of the factors causing moisture exceeds the standard. Increase the amount of air intake or appropriate adjustment of air intake and exhaust temperature is a way to solve the problem. Experienced operators should be able to adjust the operating conditions according to the changes in climate or materials, so that the system is always in an efficient working condition. At the same time should also pay close attention to the operating status of the system, the emergence of anomalies, can quickly and accurately make a judgement, in the fastest time to eliminate the problem.

3, product overheating

   Especially for heat-sensitive materials, product quality decline caused by overheating is the most common failure. There are two main reasons for this, first of all, the drying chamber gas speed is too low, the fog group drying droplets on the outside of the first to be dried. As the initial velocity of the fog group is much higher than the gas speed, resulting in upward swirling flow of dry powder into the high-temperature zone, this part of the product after high temperature deterioration and other phenomena, the main solution is to improve the gas speed appropriately. Generally in the spray part are equipped with a sight glass, from here to observe, if not produce upward spiral flow when the gas chaos is normal. Many operational examples recommend this speed in the 0.5m / s or so. Another reason is that the tail gas temperature is too high, many spray drying products with the tail gas entrainment, to be separated, so the temperature of the tail gas directly affects the temperature of the product, there is a relative temperature difference between the two, the general temperature of the tail gas is higher than the product temperature of 10 ~ 30 ℃ or so. If the temperature of the tail gas is high, the product temperature is necessarily high, more than the heat-resistant temperature of the product will make the product overheating and deterioration, the solution is to control the temperature of the tail gas outlet, the method of control is to reduce the temperature of the hot air inlet or increase the amount of liquid spray, so that the system establishes a balance of heat to meet the temperature of the tail gas outlet to ensure that the temperature of the product requirements.