Distillation trays deaerating factors 5

[AndreChE]

Dear all

Where can we find the KOCH-GITSCH DESIGN MANUAL?

I am specifically interested in literature about distillation trays design, efficiency and performance.

Besides Kister's books, which other(s) can I read and consult in order to perform tray calculations?

My focus in this moment is deaerating factors? We have revamped a C2 Splitter and we have a excessive jet flood (gamma scan confirmation). Deaerating or system factor used was 1 and this value seems not to be correct. I was told that the Koch-Glitsch manual had information on this subject.

Any knowledge about these factors? for ethylene plants columns?

Regards,
AndreChE

 

[EmmanuelTop]

AndreChE,

You may apply for KG-Tower software download:

http://www.koch-glitsch.com/koch/kg_software/kg_software.asp

and follow the procedure for distillation tray design/rating.

For high pressure hydrocarbon services (demethanizers, deethanizers), system factor is usually between 0.6-0.9, as far as I can remember. I had these numbers somewhere in the simulator software manuals, but I cannot find them at the moment.

 

[Milutin]

You can rate old trays before revamp, using actual data before revamp: feed – product data and all process data as dP across trays, temperatures and pressures.
When you are happy with this model you can use it to rate new trays. In this way, in my opinion, you will have valid calculation procedure.

Is it your column flooded from bottom to top or just particular section in column, I asking this because changing trays can lead to improper tray installation. What happens with your product quality?

Regards,

Milutin

 

[AndreChE]

We have the top section (feed to top) totally jet flooded, with severe entrainment.

Revamp was done assuming system factor of 1. I haven't found yet in the literature the SF for C2 Splitter specifically.

We have products onspec for actual rates (85% of max load) but when we increase tower feed, we feel flooding aproaching.

Installation could be an issue but we have all 75 trays jet flooded confirmed by gamma scans.

AndreChE

 

[StoneCold]

Is the tray design pressure the same as the operating pressure. That can make a huge difference if you are running significantly below the design pressure.


Regards
StoneCold

 

[AndreChE]

Yes, the same pressure.

 

[StoneCold]

Have you compared the % active area of the new trays against the active area of the old trays?

Regards
StoneCold

 

[AndreChE]

Yes, I don't have the exact numbers here but the active area is higher.

We had 5mm holes sieve trays and we have revamped for MVG valve trays.

I'll check the exact numbers tomorrow at work and write them here.

 

[Milutin]

It is unusual to me that you have all feed to top trays flooded and that you have top product on specification.
It is necessary to increase throughput and confirm flood, if it appears.
Because flooding starts from feed tray, you can first check feed distributor, feed tray and upper tray drawings, and when you shoot down column pay special attention to inspection of this internals.

You can ask via internet to download SULCOL, Sulzer tray rating software, there they have procedure for MVG trays rating. They recommend System Factor for top section of DeC2 0.85, your system is similar to this.
I can also recommend you book “Packed Tower Design and Application” by Ralph F. Strigle, Jr., author in chapter 9, Pressure distillation, discuss this subject. According to author this value can be as low as 0.7. for light hydrocarbons fractionators.
You also can tray reference from same book: Strigle, R. F., CEP , Vol. 89, No.8, 1993, p. 79.

Regards,

Milutin

 

[jamesbanda]

Andy,

There are some very valuable comments above by people that know your system better than me.

But, have you contacted KOCH ? Since you purchased the trays from them i am sure they will want to understand the performance shortfall - i assume KOCH was involved in the design.

I know in the UK the tray rep is excellent and often helps out in these situations and will travel to clients locations - i dont know the T/C of your job or working relationship with Koch to know if it would be free or incurr a charge.

Apart from that.. i you have problaby done the following checks already becuase you seem to have done a comprehensive anaylsis.
This is what i would make sure of:
> Validated Heat and mass balances.
> Validated your simulation.
> Benchmarked the column v internal columns you have installed.
> Checked for traped components or leaking hx.
> Conditions change - i've seen this several times when we blamed a the designer only to findout we had drifted pressure trapping..even if the EI folks tell you it cannot be wrong- make sure they check.
> any recent instrument calibrations or
> read kisters book on common troubleshooting issues / failures /flood cases.

 

[AndreChE]

Yep.

 

[emrekop]

Dear all, in our project we are going to install column trays and internals of some equipments like ben-free splitter and etc. what criteria should be considered during bolting the trays and internals to the equipment regarding torque values...