Differences between positive pressure and negative pressure operation of the benzene removal tower
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Are the processes for operating the benzene removal tower under positive pressure and under negative pressure the same? What are their advantages and disadvantages? Thank you in advance
Does operating at negative pressure at a lower temperature save steam?
Currently, benzene removal towers are generally operated under positive pressure in a stripping mode. Operating under negative pressure would reduce the pressure above the liquid layer, thereby increasing the driving force for evaporation and lowering the boiling point; however, this approach comes at a high cost and may not be cost-effective.
Traditional ripening is a positive-pressure process, while there are some successful experiences with negative pressure. Negative pressure reduces the vapor phase partial pressure during benzene distillation, which facilitates the distillation of crude benzene at lower temperatures. However, the safety of negative pressure systems is not as good as that of positive pressure systems; crude benzene is highly toxic and classified as a Class A flammable and explosive substance. When designing such equipment and pipelines, higher requirements are placed on negative pressure systems, with differences in materials and inspection methods. More attention should also be paid during runtime.
Designs for negative pressure operation have existed abroad for a long time; it is said that they help save energy and reduce emissions.
Negative pressure eliminates the final cooling section, which is an advantage, but the driving force for absorption is significantly lower than that in positive pressure, and the pipes become thicker, which are disadvantages.
The yield should be higher, the investment isn’t too large; just add a vacuum pump
The question you have raised is highly unprofessional. For benzene removal towers, there are currently atmospheric pressure towers and reduced pressure towers; the so-called reduced pressure towers use direct steam to lower the distillation temperature of benzene, rather than vacuum distillation as you mentioned.