Color problem of powder in spray drying bag filter

No matter what kind of powder is produced, the color of the powder in the bag filter is different from the color of the powder in the tower. For example, the powder in the milk powder production tower is light yellow, and the powder in the bag filter is grayish white.

In the production of tea powder, the powder in the tower is brownish yellow for green tea, and the yellowish green in the bag filter (green in the yellow) is lighter than the color of the powder in the tower.

The main reason is that the wet liquid temperature is reflected in the atomization drying process, and the separation of the powder and the water is realized by the continuous evaporation of the water in the liquid, and the water is settled in the tower by the exhaust fan through the cyclone separator. The bag filter is discharged to the atmosphere, and the exhaust air carries a small amount of fine powder. This part of the fine powder is too small to settle and enters the exhaust air filtration system, and the temperature of the instant tea powder is generally not more than 75 ° C, and fine The actual temperature of the powder is about 40 °C. Since the fine powder is carried to the filter and is always separated from the lower humid air, the temperature of the powder after separation should not exceed 40 °C, so the color of the powder is light yellow and light.