Control method for distillation pressure columns—separation of azeotrope systems
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Previously, pressurized towers were primarily designed for the separation and purification of systems with azeotropy, such as acetonitrile and methanol, acetonitrile and water, **furan and water. The operating pressures are all low. During debugging, the control methods mainly include: restricting the circulation volume of water, introducing inert gas at the top of the tower, and using submerged condensers. The short-term effects are all good, but the long-term stability is poor after introducing DCS automation. Are there any other more suitable operations besides these control methods? Are there any friends who have used similar pressure tower equipment? I’m curious to know how stability is achieved in such systems
Could a third component be introduced to carry out atmospheric distillation separation?
Pressure distillation might still be the more reasonable option; with a DCS in place, it should be easier to control than manually
For pressure control, it seems that adjusting the steam flow to the reboiler is the best approach!
Reply to 2# wdh2010: It’s completely fine. However, it's necessary to find a suitable third component. And the yield and energy consumption in the later stages must also be taken into consideration. Currently, for processes such as the separation of a mixture of furan, water, and propanone, as well as the separation of acetonitrile from water, it is possible to use a third component in order to carry out azeotropic distillation or extractive distillation. And it has excellent industrial applications. If you want to know more, add me on QQ: 127852242
Reply to 3# sapphire2004: It is indeed difficult to control, especially for the separation in the pharmaceutical industry where strict requirements are imposed on the third component.
Reply to 4# cgp188: I have been working on distillation design for a long time. Several devices have also been tested in this regard, and they are working well. Such pressure towers are generally controlled by DCS. However, from the initial exploration of data to the final settings, there were significant differences in the selection of control points. I’ve been thinking about whether there are better ways to control it. It mainly relates to the control of pressure inside the tower, while also taking into account the stability of the products obtained.
Reply to 5# cgp188: This is also a solution. But could you be more specific? For example, at present there is no restriction on the amount of water circulating in the distillation towers I have designed. Could this lead to all the steam heated inside the tower being condensed, resulting in wasted energy? Conversely, would it be necessary to refine the calculations regarding the area of the top condenser or to control the amount of condensate water added to the tower?