Vacuum drying oven is suitable for enterprises, colleges and universities, scientific research institutions and other laboratories to concentrate, dry and heat the articles under vacuum conditions. The product is heated in a vacuum drying oven. The vacuum drying oven has the following advantages: it can reduce the drying temperature and shorten the drying time. Avoid heating and oxidizing certain objects under normal conditions, and avoid damaging dust particles and killing biological cells by heating air.
99% of the problems in vacuum drying oven are caused by vacuum pump, so it is necessary to choose a suitable vacuum pump.
According to the conditions of drying materials, for example, if the water content of materials is greater than 10%, the water ring vacuum pump shall be selected, so that the tube condenser (category: heat exchange equipment) and buffer tank are not needed, but its limit vacuum difference is generally -0.08mpa. The air blast drying box is suitable for drying, baking, wax melting, sterilization and solidification in industrial and mining enterprises’ laboratories, medical and health institutions and scientific research institutions.
If the water content of the material is small, the rotary vane vacuum pump can be selected, so that the vacuum degree can be improved, generally at -0.097mpa, without the use of tube condenser (category: heat exchange equipment) and buffer tank.
If the vacuum degree is high and the moisture content of the material is high, the rotary vane vacuum pump can be selected. In addition, a tube condenser (category: heat exchange equipment) and a buffer tank can be added.
The rotary vane vacuum pump generally uses vacuum pump oil as the vacuum medium (the decisive material), which has the advantage of high vacuum degree, generally reaching – 0.097mpa, and is also very convenient in use. The air blast drying box is suitable for drying, baking, wax melting, sterilization and solidification in industrial and mining enterprises’ laboratories, medical and health institutions and scientific research institutions. But it also has some disadvantages. First, the vacuum pump is relatively expensive, and the vacuum pump oil is often pumped into the gas containing water or pollutants, which affects the oil quality. The use of deteriorated vacuum pump oil is easy to cause damage to the vacuum pump, so the vacuum pump oil needs to be replaced frequently.
The water circulating vacuum pump generally uses water as the vacuum medium (the decisive material). The advantages are that water is more commonly used and easy to obtain, and the price of the vacuum pump is cheaper than that of the rotary vane pump. The disadvantages are that the vacuum degree is lower than that of the rotary vane vacuum pump, generally around – 0.08mpa. When the vacuum reaches – 0.06mpa, the speed is slower than that of the rotary vane pump. The box body of blast drying box is made of angle steel and sheet steel. Glass fiber insulation is filled between the shell and the working room. The heating system is installed on the top of the working room. This type of drying box equipped with blast can effectively avoid gradient temperature difference and temperature overshoot in the working room, and can improve the temperature uniformity in the working room.
According to the performance of the two kinds of vacuum pumps, choosing a suitable vacuum pump for the vacuum drying oven can reduce the cost waste in the use process. Users with low vacuum requirements can use water circulation vacuum pump, and users with high vacuum requirements can use rotary vane vacuum pump.
The samples are divided into low boiling point and high boiling point:
1. If low boiling point sample is selected, corrosion-resistant diaphragm pump can be selected. Its drying operation and chemical resistance are great advantages. Therefore, it is particularly suitable for the concentration and drying of some chemicals, and the tail gas treatment is relatively simple.
2. For high boiling point samples, rotary vane type oil seal vacuum pump can be selected. If more organic solvent volatilizes, cold hydrazine can be added between vacuum drying oven and pump to condense and recover organic solvent.
Cold trap vacuum pumps are connected and used to capture condensable steam from moist air or solvents. The vacuum cold trap can be used for various operations. Commonly used coolants are liquid nitrogen and dry ice.
Ultra low temperature cold trap cooling system:
It is used for vacuum drying and vacuum distillation to protect vacuum pump, for low temperature water bath or rapid inhibition of enzyme reaction, especially for experiments requiring low temperature. It can replace dry ice for cold trap cooling in laboratory, avoiding the trouble of using dry ice.