The temperature fluctuation of molecular distillation equipment is affected by many factors, which can be mainly divided into four aspects: equipment itself, material properties, operating conditions and external environment:
1. Equipment itself factors
Unstable heating system: Unstable heating power will cause the heat provided per unit time to change, resulting in temperature fluctuations. For example, when the resistance wire is heated, if its resistance value changes due to aging and other reasons, the power will change. Failure of the temperature control system can also cause temperature fluctuations, such as inaccurate temperature sensor accuracy, feedback temperature value and actual deviation, causing the controller to issue an erroneous command; or the controller itself fails and cannot accurately adjust the heating power.
Low efficiency of the condensation system: Scaling on the condenser surface will reduce the heat exchange efficiency, so that the steam cannot be fully condensed, and part of the steam returns to the evaporation surface, affecting the evaporation temperature. If the flow rate of the condenser cooling medium is insufficient or the temperature is too high, it will also lead to insufficient steam condensation, resulting in unstable evaporation temperature.
2. Material property factors
Complex material composition: Different components have different boiling points. During the distillation process, the low-boiling point component evaporates first, and the high-boiling point component evaporates later. As the distillation proceeds, the material composition changes continuously, and the boiling point also changes accordingly, resulting in temperature fluctuations.
Changes in material moisture content: If the initial moisture content of the material is high, in the early stage of distillation, a large amount of water evaporates and absorbs a large amount of heat, causing the temperature to drop; as the moisture decreases, other components begin to evaporate, and the temperature will rise again.
3. Operating condition factors
Unstable feed rate: If the feed rate is too fast, the amount of material in the evaporator increases, the heat supply is relatively insufficient, and the temperature drops; if the feed rate is too slow, the amount of material in the evaporator decreases, the heat is excessive, and the temperature rises.
Unstable vacuum: Molecular distillation is carried out under reduced pressure conditions, and the vacuum affects the boiling point of the material. Vacuum fluctuations will change the boiling point of the material and cause unstable temperature. For example, vacuum pump failure and poor sealing will cause the vacuum to drop, the boiling point of the material to rise, and the temperature to rise.
Unstable speed of the scraper: The function of the scraper is to form a uniform film on the evaporation surface of the material and increase the evaporation area. Unstable speed will cause uneven film thickness, affect evaporation efficiency, lead to local temperature differences, and cause overall temperature fluctuations.
4. External environmental factors
Changes in ambient temperature: Changes in ambient temperature will affect the heat dissipation of the heating equipment and condenser. When the ambient temperature rises, the heating equipment will dissipate heat more slowly, which may cause the temperature to rise; when the ambient temperature drops, the condenser will dissipate heat faster, which may cause the temperature to drop.
Supply voltage fluctuation: The molecular distillation equipment relies on electric drive. Unstable supply voltage will cause the heating power and motor speed to change, affecting temperature control. If the voltage is too high, the heating power will increase and the temperature will rise; if the voltage is too low, the heating power will decrease and the temperature will drop.