How does a vacuum drying oven work
DZF-6050 vacuum drying oven is a kind of environmental testing equipment, currently widely used in environmental protection, agricultural scientific research, medical and health, chemical and pharmaceutical and biochemical fields, and its interior can be filled with inert gas, especially suitable for rapid drying of complex or easy components Oxidized, easily decomposed, heat-sensitive substance.
The structure of the vacuum drying oven:
The outer shell of the vacuum drying oven is formed by stamping, folding and welding of steel plate. The surface of the outer shell is treated with high-strength electrostatic spray coating, and the paint film is smooth and firm. The working room is made of carbon steel plate or stainless steel plate by folding and welding, and the insulation cotton is filled between the working room and the shell. Inside the studio, there are shelves for test samples, which are used to place various test items, and heaters are installed around the walls of the outside of the studio. The door seal is sealed with a silicone rubber strip. The evacuation and inflation of the vacuum drying box are controlled by solenoid valves. The electrical box is on the left or lower part of the box. The front panel of the electrical box is equipped with vacuum gauges, temperature control instruments and control switches. The electrical box is equipped with electrical components.
The working principle of vacuum drying oven
The vacuum drying oven can maintain a certain degree of vacuum in the working chamber and use an intelligent digital temperature regulator to set, display and control the temperature. The temperature signal is collected by platinum resistance. The PID control signal is obtained by the amplification of the temperature controller and the comparison with the set value. The control signal will control the on and off of the thyristor, and the thyristor will control the heating state of the heater to achieve automatic temperature control the goal of. The intelligent temperature regulator has an over-temperature protection function. If the temperature in the working room exceeds the set temperature value during the operation of the equipment, the over-temperature protection circuit will act and cut off the heating circuit.
According to the actual situation, the material drying process can be roughly divided into three stages: rapid evaporation of water, from liquid to solid and solid material drying.
1. Rapid moisture evaporation stage
The state of the material varies from viscous to extremely viscous. In the vacuum state, the convection heat transfer inside the material is strong, and the water evaporates quickly. At this stage, more than half of the water is evaporated, and it takes very little time.
2. From liquid to solid
The state of the material ranges from extremely viscous to fully solidified. At this stage, the convective heat transfer inside the material gradually weakens and the process is slow. The upper and lower two layers of compaction that appeared earlier have greatly affected the drying speed.
3. The process of solid drying of materials
The material is slowly dehydrated to a block with the moisture content reaching the standard. There is very little water evaporated in this stage, and the drying speed is slightly faster than in the second stage.
