I’m not sure which pump is suitable for vacuum concentration
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This post was last edited by jackwen on 2017-9-26 at 16:40. I have a saline solution that needs to be concentrated, and then the salt can be recovered through crystallization and centrifugation. I would like to use vacuum concentration. I currently have heating steam at 120°C, and I need to select a pump or a Roots blower to create a vacuum, so as to ensure that the brine can evaporate at a low boiling point. I wonder if either type of pump or Roots blower can achieve this? The table below shows my data. If a Roots pump is used, the vacuum level can only reach 0.005 MP; at this level the boiling point is 117.5°C. With heating steam at only 120°C, the temperature difference is too small, so this approach clearly isn’t feasible. Is there a vacuum pump that can achieve a vacuum level of 0.078 MP, so that evaporation can take place at 85.5°C? Or a lower vacuum level will also work. I only ask to minimize steam consumption for heating (we don’t have a boiler, so we have to buy steam from others, which is a bit expensive). The vaporization heat is not recovered, but the condensate water is recovered. Vacuum level, MP; Boiling point of saltwater, °C: 0127 –0.005117.5 –0.02114 –0.024 –0.03111.4 –0.04–107.4 –0.054101.8 –0.06297.8 –0.07189.6 –0.07586.6 –0.07885.5 –0.160
Any vacuum pump will do; the key is whether your cooling system is capable of handling the amount of evaporation, that is, whether it can keep things cool. If it can cool down, the vacuum level will naturally increase.
This post was last edited by jackwen on 2017-9-26 at 16:33. For cooling, I can use a heat sink, pour cold water over the pipes, or use a cooling tower. Recover the evaporated condensate water; it is not necessary to recover the heat of vaporization.
Buy a unit: a single-stage reciprocating two-stage Roots pump with a maximum vacuum of 50 Pa (absolute pressure). Just calculate the evaporation rate and select the appropriate power
Are you sure there’s nothing wrong with your data? (It clearly seems incorrect.) Also, for a rotary vane pump, the vacuum level shouldn’t be 0.005 MPa; it should be at least 0.05 MPa. It is recommended that you verify your data and consult the Roots pump manufacturer.
Vacuum pump unit with water ring vacuum pump + Roots pump
We consulted the manufacturer, and they said that the Roots pump can only achieve a vacuum level of 0.005 MPa; all the data I mentioned were obtained through experiments I conducted myself