English Translation
Distillers’ grains dryers rely on heat sources to supply heat, which warms the air inside the drying cylinder and dries the materials within it. To ensure the drying performance and efficiency of the dryer with this working method, it is essential to maintain the temperature of the hot air, namely the stability of the inlet and outlet temperatures. Dryers require different temperatures for drying various materials; generally, the flue gas temperature at the dryer inlet ranges from 600 to 800℃, and the waste gas temperature at the dryer outlet is between 80 and 120℃. Abnormally low or high inlet and outlet temperatures will both compromise drying efficiency and the quality of finished products. The control of the dryer’s furnace temperature is generally monitored and adjusted by furnace operators with reference to thermometers. How to judge the temperature stability of a distillers’ grains dryer? Check the key points below:
How to Maintain Stable Temperature of Distillers’ Grains Dryers
- Maintain the optimal temperature: Drying temperatures vary with different material types and moisture levels. In light of the specific material type and moisture content, the flue gas temperature at the dryer inlet should be controlled at 600～800℃ and the waste gas temperature at the outlet at 80～120℃ under normal circumstances.
- Do not raise the temperature arbitrarily: Sometimes the internal temperature of the cylinder may drop due to overly fast material feeding. Even in this case, do not randomly increase the temperature of the hot blast stove. Instead, adjust the feeding rate according to the moisture content of the discharged materials after drying, or open the damper of the induced draft fan to prevent material ignition inside the cylinder. In addition, if the discharged materials contain excessive moisture due to insufficient drying, do not adjust the temperature either; open the damper of the induced draft fan wider to enable more sufficient contact between the hot air and raw materials.
- Well control the outlet temperature: If the outlet temperature of the dryer is too low (below about 55℃), condensation and dew formation will occur. This leads to dew condensation inside the electrostatic precipitator, causing phenomena such as electric discharge and creepage, which reduces dust removal efficiency and corrodes the polar plates and discharge wires inside the electrostatic precipitator. It may also cause vibration of the fan impeller and accelerate fan damage. Therefore, when operating the dryer, the outlet temperature must be kept at the optimal level to achieve the ideal drying effect.
How to Lower and Raise the Furnace Gas Temperature of Distillers’ Grains Dryers in Daily Operation?
Methods to lower the furnace gas temperature: Reduce the air volume of the blower under the furnace hearth, add less coal, open the furnace door to introduce cold air, and open the cold air valve.
Methods to raise the furnace gas temperature: Increase the air volume of the blower under the furnace hearth, clean the grate and remove slag, add more coal, and close the cold air valve. The coal feeding amount should follow the principle of “small and frequent feeding”.
To adapt to the production of various material types, a stepless speed-regulating motor is recently adopted for the hot air fan in front of the dryer, which allows for convenient adjustment of the temperature difference between the head and tail of the dryer as required by different production formulas. If a variable frequency speed-regulating motor is used for this fan and the temperature is controlled by a computer, the temperature adjustment will be more rapid and precise.
In addition to temperature monitoring by thermometers, experienced operators can also make specific operational adjustments by observing the color, dryness and moisture of the finished materials. Only in this way can the temperature balance and stability of the dryer be ensured, thereby guaranteeing the drying output.