Effect of distillation column pressure drop on kettle temperature
Thread Content
The tower pressure drop in the distillation column decreases; why then does the temperature in the reactor drop? This question was raised by a professor of chemical engineering principles at Tianjin University. Everyone is welcome to discuss
Inside the distillation tower, the condition is saturated; therefore, as pressure decreases, the temperature also decreases
Of course, pressure is directly proportional to temperature. .
The question refers to the relationship between tower pressure drop and temperature, not the relationship between tower pressure and temperature
The question refers to the relationship between tower pressure drop and temperature, not the relationship between tower pressure and temperature
A lower pressure drop indicates less gas phase inside the tower, and the reduced amount of gas phase is caused by a lower temperature in the reactor
First of all, the client needs to understand that when we talk about the tower pressure in a distillation column, we are referring to the pressure at the top of the column. Because typically, the top pressure is regulated using a control method via a control valve. So, simply put, a decrease in column pressure drop means that, under normal control conditions, there is no significant change in the pressure at the top of the column, and as a result the pressure at the bottom of the column decreases. So, the temperature at the bottom of the tower naturally decreases. So I think when people say that the tower pressure drop decreases, they are referring to a decrease in the pressure at the bottom of the tower.
Typically, the operating pressure of a distillation column is controlled by the top pressure of the column. When the operating pressure at the top of the tower remains constant, a decrease in the pressure drop across the tower means that the operating pressure at the bottom of the tower also decreases accordingly. This results in a reduction in the partial pressures of various components in the liquid phase at the bottom of the tower. If the mass concentrations of these components remain unchanged, then according to Raoult’s law, a decrease in partial pressures implies a decrease in the saturated vapor pressures of those liquid phases. According to Antoine’s equation, this indicates that the operating temperature of the liquid phase at the bottom of the tower also decreases.
The analysis is well-reasoned and logical.
Another possibility for a low vapor phase is a low content of light components in the feed.