Many people may not know what the vacuum unit is. It is a combination of a Roots vacuum pump and a water ring vacuum pump. I believe that everyone will not be unfamiliar with these two devices. What we are talking about today is about the vacuum refrigeration of vacuum units. Let's take a look.
1. The vacuum degree and pumping speed required by the vacuum unit when used as a vacuum pre-cooler are relatively high, so it must be matched according to the actual situation when selecting. The vacuum unit is used as a vacuum pre-cooler in the processing of cooked meat: 1/3 of the cooked meat to be placed in a cubic reactor, and the temperature of cooked meat is about 90 °C, which needs to be vacuumed. The temperature of the cooked meat is lowered to about 20 ° C, and the required time is 30 minutes or less. The evaporation amount of water vapor is 20 kg under vacuum negative pressure every 30 minutes.
2. Because the molecular booster pump has high withstand voltage, the foreline pump can be easily placed in a high flow state; and the molecular booster pump has a high suction pressure, which slows down the pre-pumping load of the foreline pump. The molecular booster pump can operate at 100-50Pa. The foreline pump is from the atmosphere to this pressure, which basically follows an order of magnitude reduction in pressure per elapsed time. Therefore, the unit can have high pumping efficiency. Simplifying the high vacuum unit and eliminating the Roots pump is another advantage of the molecular booster pump.
3. For larger high-vacuum applications, the pre-pumping capacity of the foreline pump can be appropriately strengthened to further shorten the pumping time. Since the pre-pumping time is short compared to the entire exhaust process, the use time of the foreline pump It is also very short, so it can double as a pre-extraction of multiple sets of equipment, which is often very realistic.
4. In the presence of air (or oxygen) and metal catalyst, the vacuum pump oil will exhibit acid value, viscosity change and precipitate formation in the oxidation time at a certain temperature. Oxidation will occur with the application process, so some aldehydes, ketones, acids and colloids, asphaltenes and the like are gradually formed, and oxidation stability is to suppress the above-mentioned properties which are not favorable for the use of oils.
I believe that after reading this, everyone has a certain understanding of the vacuum unit. These are some simple introductions to the vacuum refrigeration effect, hoping to help everyone better understand the vacuum unit.
