Can mechanical vacuuming replace steam vacuuming?
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Question: For the vacuum distillation of oil products using a wet process, the original design for the top of the vacuum tower called for steam-based vacuum creation (comprising a booster, a primary evacuator, and a secondary evacuator). Given the current level of technological development, can mechanical vacuum pumping replace traditional steam vacuum pumping, and what is the performance? :handshake :lol Operating temperature and pressure: Top temperature of the vacuum tower: 70℃ ； Pressure: 4kPa(a). Pumping medium and quantity: ①Non-condensable gas: 1.5 kg/h (molecular weight: 22.9) ； ②Air: 20～70kg/h ； ③Condensable oil and gas: 374 kg/h (molecular weight: 180.6) ； ④Water vapor: 588 kg/h.
It should be possible; our facility uses a mechanical vacuum pumping system that can achieve a vacuum level of over 97 KPa. The effect is pretty good. The main thing is to control the adjustment properly.
It was said upstairs that the vacuum level can reach over 97 KPa; is this a relative vacuum level, or should it be -97 KPa? Also, may I ask what kind of device and specific operating conditions they are? Could you share that information? :P
Mechanical vacuuming can replace steam vacuuming; it is a well-established application. The key is the selection and maintenance of reliable units; some manufacturers perform quite well in this regard. There are not many refining units; other chemical plants, such as those for chlor-alkali production, use them more frequently. From an energy perspective, the difference between the two methods is not significant. It’s a good idea to choose hydraulic vacuum pumping for newly installed units; by adding a small pump and using hydraulic circulation in place of steam, at least the enthalpy of phase change associated with steam can be saved. Maintenance is also much simpler than that of the engine unit. It’s just a bit expensive; it’s not cost-effective to modify the device.
I don’t know why it’s not used much in refining plants – what is the bottleneck? It should be noted that steam-based vacuuming involves high energy consumption and operating costs, and it generates oily wastewater, posing significant environmental pressures. If it is feasible, how can the companies affiliated with Sinopec and CNPC remain indifferent and take no action? . . Isn’t this contrary to the basic national policy of energy conservation and emission reduction? ! :$
Convert the above flow rate to a volumetric flow rate, and then check the pumping capacity of the corresponding mechanical vacuum pump. As long as it’s suitable, that’s fine. They can be used in parallel as well as in series.:lol
The proven approach at present is to combine mechanical vacuum extraction with steam vacuum extraction. Depending on the water cooling effect at the top of the tower, it is necessary to consider whether to install a booster; if the saturated vapor pressures of the water at the tower top and the non-condensable gases can be well controlled, then a booster is not required, thereby minimizing the use of steam for vacuum extraction and reducing the water cooling load.
Could you briefly introduce the applications of the devices you are familiar with: handshake
Looking at the history of oil refining, mechanical vacuum pumping was used from the very beginning. The costs associated with replacing parts, carrying out repairs, and electrical disturbances all contribute to increased production costs. Using steam for vacuum pumping helps to reduce labor costs; it is also safe and reliable, as it does not cause changes in vacuum level due to short-term power outages. This is especially important when there are few operators working at the facility
Is it 20 or 70 for the air? A difference of three times exactly?
Vacuum degree refers to the level of vacuum, and its value is a positive number. Additionally, mechanical vacuum pumping can replace steam vacuum pumping, as it has lower operating costs, which is why many organizations choose to use it.