Distillation column feed preheating

A careful evaluation and testing would be needed to determine the optimal location for the feed tray.
  • #1
pradeepbarola
7
0
Refer to the attached drawing for more details .

In this distillation column acetone is to be separated from a mixed feed coming at ambient temperature. It is a packed column with mellapack packings. Steam is used in the reboiler (thermo syphon) for heating. Details of these streams are
Feed: 600 kg/hr (72% acetone, 17.5% water & 10.5% aniline)
Steam: 600 kg/hr, 3 bar-g
Boiling point of acetone is 56 degC. I want to use the steam condensate coming from the reboiler for preheating the feed upto acetone boiling point(without vaporization).From the calculations it comes out ~203kg/hr of condensate is required and a plate heat exchanger can be used for this.
But since I have 500 kg/hr condensate available, it can be used to vaporize the feed to some extent.
Questions:
1. How do we enter the partially vaporized feed into the column i.e. will any changes be required in the existing piping and pumping system.
2. Location of PHE: should it be kept below reboiler level to avoid flooding of reboiler or 3 barg pressure is sufficient to have continuous flow.
3. Location of feed tray: since the feed is near saturation or vaporized w.r.t acetone, I thing feed tray location can be lowered further(refer pic. y>x) and it might increase the product purity as well.
 

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  • #2
Is this feasible? 1. Yes, changes to the existing piping and pumping system will be required in order to enter the partially vaporized feed into the column. The exact changes will depend on how much of the feed is being vaporized, and what components need to be separated from each other.2. The plate heat exchanger should be kept at or above the reboiler level in order to avoid flooding of the reboiler, as this would reduce pressure in the system and make the flow of condensate more difficult. A pressure of 3 barg should be sufficient for continuous flow.3. It is possible to lower the feed tray location further, and this could potentially increase the product purity. However, this should be done carefully, as the lower location of the feed tray could also disrupt the natural flow of the column and cause problems with separation efficiency.
 

1. What is distillation column feed preheating?

Distillation column feed preheating is the process of heating the feed stream before it enters the distillation column. This is done to increase its temperature and reduce its viscosity, making it easier to separate into different components during distillation.

2. Why is distillation column feed preheating necessary?

Distillation column feed preheating is necessary because it helps to improve the efficiency and effectiveness of the distillation process. By preheating the feed stream, the energy required for the distillation process is reduced, and the overall separation of components is improved. It also helps to prevent fouling and clogging in the distillation column.

3. How is distillation column feed preheating achieved?

Distillation column feed preheating can be achieved through various methods, such as using heat exchangers, steam jackets, or electric heaters. The specific method used will depend on the type of feed stream and the available resources.

4. What are the benefits of distillation column feed preheating?

The benefits of distillation column feed preheating include improved energy efficiency, better separation of components, reduced fouling and clogging, and increased overall process efficiency. It also helps to reduce operating costs and increase the lifespan of the distillation column.

5. Are there any drawbacks to distillation column feed preheating?

One potential drawback of distillation column feed preheating is the initial investment required for equipment and installation. However, this cost is often offset by the long-term benefits and cost savings. Additionally, proper design and maintenance can help to mitigate any potential drawbacks.

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