I need help calculating the secondary condenser for distillation or rectification
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I need help figuring out how to calculate a secondary condenser and how to determine the condensation temperature. For the secondary condenser in the projects we’ve worked on in our small yard, there’s no need for any complex calculations; a 20 m2 unit is sufficient. I was wondering if anyone has already carried out such calculations. For example, in a system where the boiling point of organic substances is 60°C under negative pressure, the inlet temperature of the circulating water used for primary condensation is 32°C, which cools the gas phase of the material to 40°C; the freezing water used for secondary condensation has a temperature of 5°C. How should the flow rate of gas going to the secondary condenser be calculated, without taking into account non-condensable gases? The saturated vapor pressure is related to temperature; of course, the lower the condensation temperature, the less volatilization occurs. Are there any resources available that show the relationship between volatilization and temperature?
For negative-pressure distillation systems, if the process material contains virtually no non-condensable gases, the load on the top secondary condenser is primarily determined by the amount of air that leaks in, as well as the material loss resulting from the evacuation exhaust gases and environmental considerations. Based on the actual operating conditions, the designer selects a value that is a certain proportion of the heat load of the primary condenser, leaving an appropriate margin to accommodate changes such as high-load operating conditions resulting from the treatment of substandard material, higher temperatures of the circulating water in summer, scaling on the circulating water side of the primary condenser, and increased air leakage due to reduced system sealing. In any case, the cooling capacity of the secondary condenser should be no less than the load calculated based on the normal amount of air leakage and the cooling required for equilibrium condensation, or it can be set at 10% of the heat load of the primary condenser (15%, 20%, etc., depending on the specific operating conditions); a relatively lower percentage value should be used when the tower operates with a high reflux ratio.