Hot Carbonate System CO2 removal from Synthese Gas 1

[TinusE]

We have an UOP Benfield process installed in our plant. The process or unit description is Benfield "Modified hot carbonate gas treatment system" We are sending a LPG stream through the Benfield process to absorb the CO2 before it enters a cryogenic process. The gas is coming from the synthol reactors.

What I would like to know is the following:
1) Where can I get VL equilibrium kurve for CO2 vs K2CO3 or KHCO3?
2) How can I evaluate the absorption columns if I do not have the equilibrium data?
3) How does one tackle a problem with regards to chemical reaction absorption. Since you do not have origenal design data?
4) The K2CO3 solution is in circulation, what is the maximum amount of solids allowed in such a circulation stream such that it does not cause any problems with regards to foulingblockages of random packed beds? 2 in Pall rings and CMR's.

Best Regards
Tinus

 

[TBARBill]

1. Some V/L data sources are U. S. Bureau of Mines Report of Investigations No. 5484 (1959) and 5622 (1960) (both original equilibrium studies) and U. S. Bureau of Mines Bulletin 597 (1962 - a summary of pilot plant data) by J. S. Field and J. H. Benson et al. I'm sure there are others, plus UOP could probably swamp you with data and help. We may have some old data here at SACROC, but the Hot Pot trains have been shut down for over 4 years.

2. There are a number of articles on Benfield processes that can provide some guidelines for system design - comparing your actual performance with them (original design data would be better, but you've told us you don't have it) can give you some idea of system performance. Loading calculations on the carbonate solution should tell you if your stripper is working OK and give you guidelines for the contactor performance. The articles include "The Benfield Process for Acid Gas Removal" by Richard Bartoo (originally in Chemical Engineering Progress, October 1984, also in the book "Acid and Sour Gas Treating Processes", Stephen A. Newman, ed, Gulf Publishing, 1985) and variants "HiPure Process Removes CO2/H2S" (Hydrocarbon Processing magazine, Vol. 53, No. 2, pp 81-82) and "The Benfield LoHeat Process: An Improved HPC Absorption Method" (Paper 22b, AIChE Spring National Meeting, Houston, TX, April 5-6, 1981). The Bartoo article in the book has some typical range data, but isn't too specific. I'm sure the proceedings of the Lawrance Reid Gas Conditioning Conference (Univ. of Oklahoma, since 1952) would have several references of value. They have recently made the past papers available on CD-ROM - the complete 1952-1987 pappers (including at least some of the Fundamentals papers) are $ 100 US and are available from OU (lots of good stuff on gas treating and sulfur recovery and an excellent conference - check them out on the Web).

3. and 4. I was able to avoid deep exposure to the Hot Pot units here. The solids level was an ongoing operational problem according to the old operators, but I don't have any operating parameters.

UOP has information on their web page and should be able to provide detailled assistance.

 

[Montemayor]

I believe you're trying to analyze the HotPot process, not design it, and so are looking for the basic design information as you've outlined. If so, obtain and read the following standard CO2 separation classics:

1) Kohl & Riesenfeld; "Gas Purification"; Gulf Publishing Co.; 3rd. Ed.
2) GPSA Databook; (now in electronic CD version)
3) J.M. Campbell; "Gas Conditioning and Processing"; Vol.2; 3rd printing; 1979

That's all you need for your knowledge, unless you intend to re-design a HotPot system yourself. If so, be my guest, but you're going to need a lot more information, know-how, experience and research and just what has been published and released. Don't forget that these processes are "Proprietary". No one in their right mind is going to show you how to compete against them or to make a better HotPot process. Besides, the glory days of CO2 removal went away with the demise and slow-down of the Ammonia industry in the 1970-1980's. If you don't have a working knowledge of the above references, you'll be wasting your time on any work published by the Bureau of Mines, Benfield and countless other sources. You've got to appreciate the basics first before getting into HotPot applications

Art Montemayor

 

[TinusE]

I want to thank TBARBill & Art Montemayor for their feedback.

I appreciate it. Maybe just to clarify my own position. I am coming from a crude oil refinery and the pure chemical process engineering slightly different but I would assume that it is all the same at the end. My objective is to make sure that I understand the fundamentals of this process and thus creating a basis from where I can measure it. Not trying to compete with the UOP’s or LINDE’s. There is no basis at this stage here and every one has a theory like all engineers.

Thus I really appreciate the sharing of experience and knowledge.

Thanks Tinus Erasmus

I do have a lot of other questions but let me first get answers to my origenal questions.

There is however one question that I can not delay.
V2O5 is used as a corrosion inhibitor. Where can I get the corrosion meganism for the corrosion that is taking place, as well as the Fe reaction with the different components in the K2CO3, KHCO3 and DEA scrubbing solution? There are black deposits or solids formed during the LPG wash reaction which cause blockages in the random packed beds. Side filters and activated carbon filters are now installed but the objective is to understand what forms the black deposits/solids. We have found that these solids mainly consist out of C, H, Ucon and Fe.

 

[bankshoted]

1,2, and 3 are proprietary, although you should be able to get the design points for your plant from either the contractor or UOP. Have you contacted UOP?