Kelp drying is divided into three stages.
The first stage is: the heating stage. Put the packed kelp into the drying room evenly without overlapping, so as to avoid unnecessary air leakage when placing the trays. The temperature in the drying box is about 50°C, and the heating time is generally 1.5 to 3 hours. If there is moisture in the box, the moisture should be exhausted. If the temperature drops after the moisture is exhausted, the heating should be continued.
The second stage is the constant-speed drying and moisture removal stage. This stage is divided into two stages: high-humidity and low-temperature stage, and medium-humidity and medium-temperature stage.
In the high-humidity and low-temperature stage, the temperature should be less than 60℃, and the temperature range should be 55~60℃. To avoid the color change of the material caused by high temperature and high humidity, observe the change of water vapor on the surface of the material, and drain the moisture at any time. The time for this stage is 3~3.5 Hours.
The temperature of medium-humidity and medium-temperature is less than 60 °C, and the temperature range should be 50~60 °C. In this section, the air inlet valve can be properly opened, and the return air valve must be properly closed. The specific adjustment should be made according to the local temperature and humidity. .
The third stage is the speed reduction stage. This is also called the low-humidity and high-temperature stage. The temperature in this stage is 70-80 °C. The temperature is better not to exceed 70 °C in the early stage, and it is best not to exceed 80 °C in the later stage.