8 replies to this topic

[Beergson]

Hello,

Im designing pilot phase unit for production of new tire rubbers' modificator which will be produced by vacuum distillation @ 7kPaa. The aim of this distillation will be getting back unreacted components. For this reason vacuum system shall be provided, and thus I've question regarding vacuum pump connection for total condenser - where it shall be connected - to vapour nozzle at total condenser or to liquid vessel to extort vapors flow through condenser and its condensation?

The second question is hydraulic seal for total condenser- is it needed, or maybe it is better to put inlet liquid nozzle below liquid level at liquid vessel?

 

My solution proposal is attached. Any comments will be appreciated.

Attached Files

•  Che-mycie-kwasem.pdf   15.52KB   62 downloads

[Art Montemayor]

Beergson:

 

Your system will not work.  By incorporating a liquid condensate seal between your condensate being formed and your vacuum system, you have made it difficult - if not impossible - for all the non-condensables to be evacuated by the vacuum system.  The nefarious and troublesome non-condensable gases will collect and concentrate in the vertical total condenser’s shell side and mitigate any required heat transfer.  These gases will blanket your tubes and make condensation almost impossible.  Gases are notorious insulators against heat transfer.

 

Although your sketch is awkward and not detailed, I think I visualize what you intend to do.  I would not advise you to do it this way.  Please refer to:

 

• http://www.cheresour...ining-a-vacuum/
• http://www.cheresour...ical +condenser
• http://www.cheresour...ical +condenser

Download the workbook that deals with producing and maintaining a vacuum and follow the guidelines given in the two threads.  I don’t know why you want to use a vertical total condenser, but I would not put the condensing vapor on the shell side.  I would put the process vapor inlet at the top on the tubeside, with condensing taking place in a downward vertical manner.  I would mount the condenser on the receiver tank you show and extract the non-condensables and impose and maintain a vacuum by extracting at one far end of your receiver tank.  This I show in one of the above threads.

 

If the condensate recovered is valuable, I would add a vent condenser - as explained in the above workbook - and recover the last droplets of the condensate in the vent condenser just upstream of the vacuum system, as shown in the workbook - perhaps employing a very cold cooling fluid, such as a refrigerant or a cold glycol solution.

 

That is the way I would handle this project.  I regret that I am unable to make useful comments on your sketch because it is in .pdf format.  That is why creating and submitting drawings and sketches in Excel is so much better than anything else.  One can make comments, make calculations, insert additional sketches, and call-out critical points on an Excel spreadsheet.  All you can do with a .pdf document is look at it - unless you can afford to buy the Adobe program (which I won't do).

[breizh]

Beergson,

 

Consider this document from Graham to support your work.

Hope this helps.

 

Breizh

[Beergson]

Art & Breizh many thanks for yours valuable reply.

 

I've additional point to your reply:

1. How to ensure that condensated liquid droplets will not be sucked by vacuum pump connected to a reflux drum? - wire mesh shall be provided at vacuum pump nozzle or any special tested solution?

 

2. What's about if Customer wants to utilize existing plate heat exchanger and horizontal type exchanges as a condensers. Plate exchanger doesn't have vacuump pump suction additional nozzle so the only one solution is to connect vacuum pump by reflux drum nozzle, but horizontal exchanger (shell utilized as a condensation side) has vacuum pump nozzle at its top end. And at this point this nozzle can be connected to vacuum pump but in this way liquid can by carried over to vacuum pump - so in my opinion best way is to connect this nozzle with reflux drum as a equalizing line and then connect vacuum to reflux drum. Am I right?

[Art Montemayor]

Beergson:

 

Ensuring that there is no entrainment of condensate droplets out of the receiver vessel and into the vacuum system should not be a problem.  Careful, proper engineering should easily take care of this.  Simply design and fabricate (or purchase) an efficient separation device.  But don’t forget to locate the vacuum nozzle at the best, optimum location.

 

I don’t understand your explanation or description in your #2 paragraph.  Please furnish a detailed drawing or sketch outlining what you propose.  That way we can all comment with accurate data.

[Beergson]

I will try in othet words.
1. Does plate type HEX suitable for vacuum condenser service? Customer pressing to use existing one.
2. Is equalizing connection beetween horizontal type condenser an reflux drum needed if vacuum will be sucked by nozzles located at end of vessel and condenser is total condenser type?

[breizh]

Beergson ,

 

1) Yes it works . I'm currently operating a 3 effects evaporators and the condenser is a plate heat exchanger .

2) a drawing will save words.

 

Breizh

[Beergson]

Beergson ,

 

1) Yes it works . I'm currently operating a 3 effects evaporators and the condenser is a plate heat exchanger .

2) a drawing will save words.

 

Breizh

 

In attachment my sketch. In my opinion balancing (equalizing) line beetween reflux drum and high point of vapour line is not needed if we have sure that all vapors will be condensed. Im right?

Attached Files

•  acid-che.xls   65.5KB   27 downloads

Edited by Beergson, 09 July 2014 - 02:21 PM.

[Art Montemayor]

Beergson:

 

Your proposed sketch won't work properly.

 

See my Rev1 of your workbook for comments and the recommended installation.

 

 acid-che Rev1.xlsx   20.67KB   47 downloads