What causes the drying efficiency of the boiling dryer to be affected?

What causes the drying efficiency of the boiling dryer to be affected?

The principle of the boiling dryer is that the bulk granular solid material is fed to the fluidized bed dryer by a feeder. The filtered clean air is contacted by the solid material of the fluidized bed distribution plate heated by the bottom of the blower to form heat and mass transfer of the fluidized gas-solid two phases. The dry matter is discharged from the discharge port, and the exhaust gas is discharged from the high-level fluid bed storm and the filtered solid powder after filtration. So what are the factors that sometimes affect the drying effect of boiling dryers? Let's introduce it to everyone.

If the material is not properly dried from the boiling dryer, check that the drying chamber has enough space to provide adequate and effective drying time. Effectively effective drying time refers to the exposure of dry particles to the proper temperature and dew point. If the residence time of the particles in the bunker is insufficient, proper drying is not obtained. Therefore, we should pay attention to the size and shape of the particles or broken materials, they will affect the dry matter accumulation density and residence time.

In the dry gas path, the drying temperature should be at the inlet of this test in order to compensate for the heat loss of the boiling dryer tube. The inlet air temperature is lower, possibly due to a lack of improper supervisory controls and insulation, or heating elements, heating current contactors, thermocouples or controllers failing. In addition, it is important to monitor the drying temperature of the entire drying process and observe that the desiccant changes temperature fluctuations.

Bent hoses or clogging filters can limit airflow and affect the performance of the boiling dryer. So, if you check the boiling dryer and found no such problem, you can't determine if there is enough air. Here, there is a quick, simple, and accurate method to detect the boiling air in the boiling dryer, that is, to measure the material in the vertical vertical temperature curve.

Assume that the material supplier recommends a drying time of 4 hours and a processing capacity of 100 lbs / h = 0.4536 kg (1 lb). To determine if the boiling dryer airflow is sufficient, you can measure the drying temperature profile in the shelter, where it is important to pay special attention to the temperature of 4 h (400 lbs). If the dry box is 400 lbs inside the set temperature, you can make the gas flow sufficient. As long as 1 hour, 2 hours of drying or 3 h of material is fully heated, indicating that the gas stream cannot complete the production of heated and dried materials. Lack of heating may indicate that productivity, drying ovens are too small, or air is blocked due to filter clogging or damage to hoses, and the like. Too large a volume can also cause problems, not only wasting energy, but also causing high return air temperature and destructive performance of the desiccant.

The return air filter prevents contamination of the desiccant, which affects its hygroscopicity. These filters must be kept clean to ensure adequate air flow.

When the dry air is from the top of the boiling dryer, most of the heat is released. A boiling dryer with a desiccant temperature in the range of 150 to 120 can work effectively. If the return air dryer overheats, it will reduce its ability to absorb moisture from the dry air.

Detection often has its return air temperature. When the return air temperature is high, it may indicate productivity, the size is too large, or the dry material is hot when it enters the bin. For example, PET crystallization occurs before drying, or just some materials (such as PET) dry at a temperature higher than the normal temperature range. In order to prevent the return air temperature from becoming higher, as long as the heat exchanger is installed, the return air can ensure that the desiccant can effectively remove the moisture in the air.

The drying speed of the boiling dryer depends on the surface evaporation rate and the moisture diffusion rate. The drying rate is decreased by the diffusion rate, and the water content is reduced. This stage is called the drying speed reduction stage. Early dry drying rate surface evaporation rate control; then, as long as the external conditions continue to dry, the drying rate and surface temperature are stable, this stage is called constant speed drying stage; when the material moisture content is reduced to a certain extent, the surface of the water The diffusion rate is reduced, and the specific surface evaporation rate.