The final step in the refining process of liquid products is usually rectification. The main purpose is to maintain the physical and chemical properties of the product. The refining yield of the product is as high as possible. Take the product as the normal distillation, remove the low boiling part as the solvent and the high boiling part as the bottom material, so as to achieve the product quality index. Liquid products are usually thermally sensitive to thermal deterioration, so it is especially important to refine at low temperature.
Similarly, for economic and environmental reasons, the solvent must be recycled. Refining of liquid products requires as high a vacuum as possible, usually operating under 10Pa (one standard atmosphere is 101325Pa). The configuration that satisfies this condition is: slide valve vacuum pump, claw pump two kinds of single pump, roots vacuum unit.
(1) roots vacuum unit
roots vacuum unit operating power is quite high. For the first stage pump to achieve equivalent of claw type pump swept volume of the same unit, the unit with power for 20 Kw, for day and night continuous operation of the vacuum generating device, the difference of 12.5 Kw, of charge of electricity of a year, 90000 yuan means that the gap (work day and night 300 meter per year. The electricity charge is one yuan per degree.
(2) Piston Vacuum Pump
It must have a vacuum pump in order to work effectively. When the gas flows through the vacuum pump, it is hard to avoid the vacuum pump oil out. This means you can't apply the recycled solvent directly, or waste it and pollute the environment. In addition, the operation and maintenance requirements of the slide valve pump are high, in cold season, a little careless switch machine, very easy to damage.
(3) claw type pump
Using claw pump, there is no problem to recover the solvent at normal pressure after pump. In addition, due to its good structure, sophisticated processing and complete ancillary equipment, once put into use, it has low requirements for use, wide range of use, long service life and convenient cleaning and maintenance. When higher vacuum is required, it can be used as the front pump to form the vacuum unit conveniently.
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