How should reflux be considered in atmospheric and vacuum distillation?
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Question: In the material balance analysis of an atmospheric pressure tower, is it necessary to take the reflux flow into account? Are there similar reflux problems in the vacuum distillation column? Thank you!
It mainly depends on the range within which you choose the system for material balance. The range that is to be studied or for which a material balance is to be conducted is enclosed in a box; materials that enter are considered as inputs, while those that leave are considered as outputs. By ensuring that the total amount of inputs equals the total amount of outputs, it is possible to conduct a material balance analysis. If the reflux is entirely within the box, it need not be considered when performing material balance. When performing local material balance or heat balance for a tower, there may be inflows and outflows due to reflux at certain points, and in such cases, reflux must be taken into consideration. A similar reflux also exists in the vacuum distillation column, and the same principles must be followed for its treatment.
The backflow issue at normal pressure should be taken into account in the equilibrium analysis; the same principle applies to reduced pressure, that is, in a vacuum environment! ! :handshake
In the material balance analysis of an atmospheric pressure tower, is it necessary to consider the reflux flow? It should be considered that if the two balances of gas-liquid phase and heat within the tower are properly managed, there is no need to take reflux flow into account for the crop flow balance. The decompression analysis is the same as at normal pressure.
The range that is to be studied or for which a material balance is to be performed is enclosed in a box; materials that enter are considered as inputs, while those that exit are considered as outputs. Following the principle that the total amount of inputs equals the total amount of outputs, if the reflux remains entirely within the box, it need not be taken into account when performing the material balance. When performing local material balance or heat balance for a tower, there may be inflows and outflows due to reflux at certain points, and in such cases, reflux must be taken into consideration. A similar reflux also exists in the vacuum distillation column, and the same principles must be followed for its treatment.
From an operational perspective, it is necessary to consider the amount of reflux; for a simple material balance, only the raw materials, finished products, and residue oil need to be taken into account. There’s no need to go to such trouble.
Thank you all for your suggestions. I am currently focusing mainly on the energy consumption of the atmospheric tower; if the atmospheric tower is considered as a box, it seems that there is no need to take reflux into account ； When specifically calculating the heat taken up by the reflux, parameters such as the reflux flow rate and temperature should be considered. I wonder if my understanding is correct?
There is no need to consider the backflow. . . Vacuum distillation is a process of equilibrium vaporization. . . Given a constant amount of feedstock, as long as the temperature in the constant-pressure reactor reaches the specified value, the amount of gasoline and diesel that will be produced in the constant-pressure tower is fixed. . . In a vacuum distillation tower, the amount of wax oil produced remains constant under conditions of a constant furnace temperature and a constant vacuum level. . . :lol