Midsection of the desorption tower
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I would like to ask if anyone knows how to design a reboiler for the middle section of a desorption tower How is it working? Our mid-section design includes a reboiler, but the liquid level in the oil collection tank cannot be controlled; it is either full or empty, resulting in unstable operation. Do you all have any good usage tips? Thank you.
What does that mean? Interrupt the design of the reboiler? Isn’t an interrupt used for heat extraction?
Reply to 1#: The effort put in is appreciated. It’s rare to encounter situations where a reboiler is designed for the middle section of a stripping tower; generally, it’s sufficient to design a reboiler at the bottom of the stripping tower. Based on the situation you described, I believe the main reasons for the large fluctuations in liquid level are the small size of the intermediate oil collection tank and the excessive amount of vapor returning from the reboiler ； Of course, we also need to ask the design team to clarify what exactly the function of the reboiler in the design is If it’s not necessary, can it be removed? Of course, you could also try increasing the volume of the oil collection tank!
Reply to 2# Dongfang Zhi Dong: Some units take into account the insufficient heat supply from the heat source of the reboiler at the bottom of the heat exchanger; therefore, a middle reboiler is installed in the separation tower to utilize the low-temperature waste heat from the unit as a heat source
Mid-section reboiler. . So what are your temperatures for cold and hot feed? By the way, are there desorption towers that use pure cold feed? What is the difference between such desorption towers and those that accept both cold and hot feeds?
Our desorption tower is equipped with a mid-stage reboiler; however, the oil collection tank does not have a level gauge, so it is not possible to determine whether the liquid level is present or not. At present, we control the temperature returning to the tower to be about 20 degrees higher than that of the extracted fluid – the temperature specified by the design institute was around 10 degrees higher. Anyway, the operation is decent; it can help reduce the steam consumption of the bottom reboiler.
I’ve never worked with a mid-section reboiler; I’m not sure if this can eliminate the need for a hot feed stream And what is the heat source for your reboiler?
Reply to 6# Walking Together with the Future: The separation column operates on the principle of different relative volatilities, and higher temperatures yield better results. If the reboiler at the bottom of the tower cannot provide sufficient heat, it is possible to add another reboiler in the middle, but the gas-liquid phase loads must be carefully considered; otherwise, it will be difficult to maintain proper operation. Appropriately reduce the heat removal from the middle reboiler to establish a proper balance. I wonder if your analysis tower has cold feed and hot feed? A portion of the hot feed solves the heat extraction issue in the middle section, eliminating the need for a reboiler there.