6 replies to this topic

[Kentucky08]

Good day, everyone,

I am currently revising our existing evaporator design, as the current configuration has been observed to cause oil entrainment. We initially considered two possible causes:

1. Excess heating

2. Insufficient vapor disengagement space

After evaluation, insufficient vapor disengagement has been identified as the primary cause.

In this regard, I am reviewing the existing evaporator design prepared by my former colleague (please see the attached file: Existing Design). I am currently evaluating two revised options:

1. My proposed revision (File name: Own Design)

2. An alternative design suggestion from an external colleague (File Name: Additional Design)

While both options appear technically feasible, I would greatly appreciate your expertise and insights to determine the most suitable approach.

 

For reference, the process fluid consists of palm olein with excess methanol and water of reaction from the esterification process. Oil entrainment into the vapor stream has been observed, which affects downstream separation.

 

Thank you in advance for your guidance and recommendations.

Attached Files

•  Existing Design.pdf   78.24KB   36 downloads
•  Own Design.pdf   128.37KB   46 downloads
•  Additional Design.pdf   155.91KB   41 downloads

Edited by Kentucky08, 19 February 2026 - 01:38 AM.

[latexman]

Instead of building a new heat exchanger with superior vapor/liquid separation, why not just add a line type, high efficiency vapor/liquid separator to the vapor line and recycle the liquid back to the evaporator.  It may be cheaper, and it will keep the two unit operations separate and simple.

[breizh]

(PDF) Criteria for the vapor space design in kettle reboilers

You may want to review your calculation based on the link above.

My experience with evaporators is to use mesh to mitigate carry over of liquid (droplets) , at some stage you also need to reduce the load.

Good luck

Breizh

[Pilesar]

My initial assessment:
Your statement in your drawing seems the key point "Based on our experience, we are encountering challenges in maintaining the proper liquid level inside the evaporator"
A larger vapor space will not help if you fill that vapor space with liquid or foam! If designing the unit from scratch, I would include a level-controlling outlet weir similar to what you propose. A large enough horizontal vapor space of a type K shell can be a very effective vapor-liquid separator if properly designed. A demister pad at the vapor outlet consisting of a blanket of wire mesh would be reasonable except for that it looks like you have the feed entering at the top as a mixed phase fluid! Consider an inlet diverter pipe to better divide the feed from the outlet. Perhaps the vapor velocity is too great for a mesh pad. There are demister devices which are more appropriate for high velocity which use kinetics and a torturous path. 
  I understand that palm oil processing has special challenges. I have never worked with that material so my assessment may not apply. I do not like either one of the proposed new designs. I would insist on a bolted flange connection between the kettle and the separator vessel. Since the original vessel already has flanges, then a bolt-on separator as latexman suggested is certainly something to consider. I might consider using a few trays with a reflux stream for washing the vapor.
  Look also at the upstream processing. What has changed? Is the equipment just at the limit of its capacity? Good luck to you.

[breizh]

To add to my previous answer, consider to add  a manhole and may be a platform on the side to get access to the mesh.

Lifting equipment is expensive.

Breizh

[Kentucky08]

Instead of building a new heat exchanger with superior vapor/liquid separation, why not just add a line type, high efficiency vapor/liquid separator to the vapor line and recycle the liquid back to the evaporator.  It may be cheaper, and it will keep the two unit operations separate and simple.

 

Our initial option was to construct a separate separator unit. However, due to space limitations, we are currently considering integrating it into a single unit instead.

 

Thank you for your suggestion, Sir, and for taking the time to respond.

[Kentucky08]

(PDF) Criteria for the vapor space design in kettle reboilers

You may want to review your calculation based on the link above.

My experience with evaporators is to use mesh to mitigate carry over of liquid (droplets) , at some stage you also need to reduce the load.

Good luck

Breizh

 

Thank you for providing the comprehensive literature, Sir. I will review it carefully and incorporate the relevant concepts into my revised design.