The color of white lees is affected by the color, proportion of the raw materials, and the drying temperature and duration of the drying process, and it shows a light yellow to dark brown color. Except for raw material factors, expert studies have shown that the darker the lees feed, the lower the amino acid utilization rate. Therefore, in order to ensure that the nutrients of the finished distiller's grains are not damaged, special attention should be paid to the drying temperature and drying time when drying with a distiller's grain dryer.
At present, there are two mainstream drying methods. When choosing a lees dryer, users can learn about the effects of different drying methods on the finished lees.
1. Direct heating and drying
Direct contact of heat with wet materials and convection for heat exchange. The heat loss of this technology is small, and the solid content of the sludge can be dried from 25% to 85% ~ 95%. Although high in thermal efficiency, excessive temperatures can destroy nutrients in the distiller's grains.
2. Indirect heating and drying
Heat is circulated through the medium in a closed circuit, without direct contact with the wet lees. This method has low drying efficiency and large heat loss, so it is impossible to dry large batches of high-humidity and high-viscosity materials, but due to the low drying temperature, there is less nutritional damage.
The high-humidity and high-viscosity brewer's grain dryer is a new generation product upgraded and reconstructed by Dingli Company based on the original direct-heating tumble dryer. Its working principle is a drying process that improves the drying efficiency by appropriately increasing the wind speed and increasing the air volume when the hot air temperature is low within a set range. The finished product has good color after drying, and the nutritional ingredients will not be damaged. Moreover, after the temperature is lowered, the generation of harmful gases such as dioxin can be effectively suppressed, and the difficulty of exhaust gas treatment in the later stage is reduced.