11 replies to this topic

[Mudassir Khalil]

hi every1
i would like to know what is efficiency of valve type tray in Acid Gas Sweetening absorber and regenerator...
Please provide me with any vendor data...
Thank you

[Art Montemayor]

Mudassir:

You should know who designed, built, and sold the acid gas processing unit to you or your company and you should be contacting them instead of this Forum.

We have no way of even having an idea of what it is that your company bought and has operated or is planning to operate. You should contact the engineering company that designed and sold you this equipment and inquire with them as to what you have in your possession.

[Mudassir Khalil]

Thank you Mr Art
Actually I am in designing phase of Amine Sweetening Plant, and dont have much experience regarding this. So I am trying to get any data of vendor on which I can assume efficiency of trays and find out length of column.

[Dipankarc84]

Mudassir:

I am assuming that you want to know the efficiency of Amine Absorbers so that you can arrive at the actual no. of trays from your simulations. As Mr. Montemayor has already told you, you should be asking some standard vendors who provide Amine solutions to give you an efficiency.

However, you mention the term "valve tray" in your question. I hope you are not asking about how "valve tray" efficiency compares to other tray types. If that is what your question is, for all practical purposes, a "properly designed" valve tray will give you the same efficiency as a "properly designed" sieve tray/ bubble cap tray or any other tray.

[Technical Bard]

Most modern amine plant simulators can estimate the efficiency of trays. The best simulators are rate-based (they consider kinetics), and this is very dependent on the geometry of the column/trays.

One way you could estimate the tray efficiency is using the O'Connell charts (1946) - I know there are copies of these in Kister's Distillation Design text.

[Mudassir Khalil]

Thanks every1
Actually let me explain you what I am trying to do. I have done simulation of Amine Unit in HYSYS with taking 20 valve type trays ( general number of trays used in simulation from articles). Now to get height of tower i have to find actual number of trays for which efficiency is required.

[Dipankarc84]

Mudassir

Although I am not a simulation expert, I don't know whether HYSYS is the proper tool to use for an Amine Absorber. I hope you are taking into account the fact that Amine Absorption is not just a mass transfer operation, but also includes reactions. You have to account for the Heat of Reaction and Reaction Rates. You should be absolutely sure of the solvent you are using (e.g. MEA, DEA. MDEA), the promoters (e.g. Piperazine) and also the Process requirement (is it a CO2 removal system or selective H2S absorption system). The Temperature profile of an Amine Absorber is distinct with a bulge in the bottom half where the majority of the reactions happen. I would suggest you do some literature survey on Amine Absorption and how to model them before simply punching numbers into HYSYS or any other simulation tool. Although true for all simulations, specially for Amine Units, It is very important to match your simulation output with a valid set of Plant Data before you can draw any conclusions from this simulation.

[Technical Bard]

In response to Post #7, Aspen HYSYS using the Amines package (which is the Schlumberger DBR Amsim thermo) can be used reliably. Other good simulators for amines include BR&E ProMax, OGT ProTreat and VMGSim.

When I design amine units, it is important to assess historical operating data for similar facilities. You will find that many amine units are designed with 20 trays in the absorber just because many others have that many trays. However, if you are trying to slip CO2 with MDEA you must be more careful about the tray count.

[Propacket]

Mudassir Khalil

Perhaps you want to know the tray efficiency in order to calculate actual number of trays from no. of theoretical trays estimated by the process simulator.

For amine sweetening, all process simulators estimate component efficiency rather than the tray efficiency. Component efficiency is calculated by the simulator based on type of amine, tray diameter, weir height and weir length. No additional tray efficiency needs to be considered.

Haseeb Ali

[Dipankarc84]

In response to Post #7, Aspen HYSYS using the Amines package (which is the Schlumberger DBR Amsim thermo) can be used reliably. Other good simulators for amines include BR&E ProMax, OGT ProTreat and VMGSim.

When I design amine units, it is important to assess historical operating data for similar facilities. You will find that many amine units are designed with 20 trays in the absorber just because many others have that many trays. However, if you are trying to slip CO2 with MDEA you must be more careful about the tray count.

Thank you for letting me know. As mentioned, I am not a simulation engineer and hence my knowledge in this field is extremely limited. I was aware of ProMax and ProTreat. However, I was not aware that HYSYS too had an Amine Package.

[Mudassir Khalil]

Mudassir Khalil

Perhaps you want to know the tray efficiency in order to calculate actual number of trays from no. of theoretical trays estimated by the process simulator.

For amine sweetening, all process simulators estimate component efficiency rather than the tray efficiency. Component efficiency is calculated by the simulator based on type of amine, tray diameter, weir height and weir length. No additional tray efficiency needs to be considered.

Haseeb Ali

thankyou every 1...
Mr Haseeb Ali you mean to say that HYSYS gives actual number of trays..?
can i get your email id / contact number as i am too from Pakistan??

[Propacket]

Mudassir Khalil

Perhaps you want to know the tray efficiency in order to calculate actual number of trays from no. of theoretical trays estimated by the process simulator.

For amine sweetening, all process simulators estimate component efficiency rather than the tray efficiency. Component efficiency is calculated by the simulator based on type of amine, tray diameter, weir height and weir length. No additional tray efficiency needs to be considered.

Haseeb Ali

thankyou every 1...
Mr Haseeb Ali you mean to say that HYSYS gives actual number of trays..?
can i get your email id / contact number as i am too from Pakistan??

Yes. Specifically for amine package, Hysys will give you the actual no. of trays. However, operating experience should also be taken into account. For example, most of the amine sweetening plants are deigned with 20 trays in absorber as well as regenerator although you get less than 20 trays with Hysys. In such circumstances, multiple feed locations are frequently used in absorber to allow for flexibility.
Here are my email IDs.
engr.haseebali@yahoo.com
pengr.haseebali@gmail.com