How to estimate the evaporation rate in a pressure-reduced structured packing tower
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Question: How to estimate the evaporation rate in a pressure-reduced structured packing column with a certain tower diameter, at a pressure of 500 Pa and a boiling point below 280°C, for the intermittent distillation of fragrances.
The evaporation rate needs to be calculated based on the steam consumption; the pumping rate has an impact
I just want to estimate the steam demand based on the evaporation rate. And do you know how to calculate the evaporation rate using the kinetic energy factor method under reduced pressure conditions?
You want to calculate the maximum evaporation capacity at a reasonable gas velocity for a tower of this diameter, in order to determine its production capacity, right? I have some basic knowledge on this. According to my understanding, the tower diameter can be used to calculate the cross-sectional area; multiplying that by the porosity and adding a coefficient gives the effective flow area. Multiplying this by the gas velocity yields the actual volume flow rate, which can then be converted into a standard volume flow rate, allowing the desired evaporation capacity to be determined
:You’ve seen through the handshake:P, but I’m not sure if that’s still the case under reduced pressure. For example, if the tower diameter is 1000, the gas velocity is 3 m/s, and the molecular weight of the organic substances is 200, then the evaporation rate = 0.5*0.5*3.14*3*3600*(0.5/101)*1000/22.4*200 = 375 kg/h. This result seems a bit unreasonable; with such a large tower diameter, the evaporation rate should be higher than that.
If the porosity of 0.6 is not taken into account, the amount becomes even smaller – 375*0.6=225 kg/h
Perhaps that’s the case; with a vacuum level as high as 500 Pa, if the amount of evaporation is too great and condensation along with vacuum pumping cannot handle it, then the vacuum level cannot be maintained.@ylb913
I really haven’t come into contact with this before; there must be data on the composition of the materials, the partial pressures at equilibrium between gas and liquid at different temperatures, as well as data related to material balance and heat balance. The various data related to crude oil distillation and atmospheric and vacuum distillation should be quite comprehensive, but I have no personal experience with them.
I am working on turpentine and its downstream products. Based on actual production experience, for a tower with a diameter of 1000, the evaporation rate should be between 1–1.5 m³/h. Now we are planning an expansion, and it is necessary to estimate the evaporation rate for a certain tower diameter first in order to determine the production capacity. Anyone who has knowledge on this topic, please help me out.