Atmospheric pressure issues
Thread Content
May I ask what is the difference between tower pressure and operating pressure? Is the pressure in a atmospheric pressure tower the pressure of the gas inside the tower relative to the inner wall of the container? ?
Tower pressure may refer to the actual pressure in the tower, while operating pressure refers to the pressure under which the tower is designed to operate normally.
Tower pressure is one of the main control parameters in distillation operations. Excessive fluctuations in tower pressure can disrupt the material balance and gas-liquid equilibrium throughout the tower, resulting in substandard product quality; therefore, distillation operations must be kept stable. Methods to adjust the column pressure include: (l) When the top condenser is a fractional condenser, the column pressure is generally adjusted by the amount of vapor product taken from the top of the column. Remove the increase, and the tower pressure drops ； The withdrawal decreases, and the tower pressure rises. (2) If the steam consumption in the reboiler is too high and the reflux volume is large, the tower pressure rises; in such cases, the steam supply should be reduced appropriately to regulate the pressure at the bottom of the tower. (3) The factors affecting the change in column pressure are: ① top temperature of the column, ② bottom temperature of the column, ③ feed composition, ④ feed rate, ⑤ reflux rate, ⑥ refrigerant amount and refrigerant pressure. Additionally, instrument failures and freezing of equipment and pipelines can also cause changes in tower pressure. Operating pressure is the pressure of the medium under normal operating conditions, and can be calculated based on the process requirements.
The tower pressure should be kept unchanged as much as possible during normal operation; controlling product quality is mainly achieved by regulating the temperature through cold reflux. The top pressure indication in a atmospheric pressure tower represents the difference between the pressure inside the tower and the external atmospheric pressure. In such towers, the pressure is slightly higher than the external pressure; this helps to raise the temperature of the side products, improves the precision of distillation, and facilitates heat recovery
Sigh. . . Tower pressure = operating pressure of the tower. . . It’s the same thing. . . Generally, the pressure at the bottom of the tower is different from the pressure at the top; the difference is due to the gravity of the liquid phase. . . For the remaining provisions, see the instructions in the tolerance regulations. . . Here, I only provide the ways to find out. . . :lol
I think the original poster didn’t make it clear: if it refers to the pressure on the tower, then it’s actually the pressure under normal operation conditions; whereas the pressure that the tower can withstand is definitely not the operating pressure