5 replies to this topic

[rodolfoingeniero]

Hi Everybody,


I would like some help on selection materials for an amine sump tank (in ground).
I think its walls should be made of concrete, but why?
Does anybody know if is there any reference regarding the material selection criteria for amine sumps?
Thanks in advance

[Art Montemayor]

Rodolfo:

If you are dealing with such amines as MEA, MDEA, or others used for acid or sour gas removal, then my response to this query is: DON'T. There are many reasons for not doing what you are proposing, some of which are:

• All amines are very expensive. You simply cannot deal with them as if there were ordinary waste products;
• amines - especially MEA - are very susceptible to contamination by oxygen (air); they are converted to a variety of very corrosive by-products and consequently can do harm to your process; any concrete sump will be nearly impossible to be maintained hermetic and under a positive, nitrogen inert atmosphere.
• Any concrete, below grade sump is going to be contaminated with sand, grit, and other garbage materials; why would you subject your amine to such exposure?
• A below-grade sump means you will require a sump pump. This is a special pump and requires special controls and switches. You will also inherit NPSHa problems and requirements.
• A below-grade sump is a potential amine ground contamination problem waiting to happen. If you are in Chile, you are in earth quake country and have to expect that you will have the sump exposed to ground tremors from time-to-time. All this means potential ground contamination - and valuable chemical losses. Why would you risk this?

There are more reasons, but I think I can summarize the proposal as simply being a bad idea. Build an above-grade, elevated amine steel tank with positive draining and visual liquid level detection. That's what I built in Lima, Peru in 1963 for my gas processing plants there and the tank lasted for over 35 years.

[rodolfoingeniero]

Art,

Thanks for your prompt response.
Maybe I have to reformulate my question given that this matter is about an existing amine sump which is located in ground and obviously quite hermetic.
This amine sump is part of a prime G unit, which was built here in Chile eight or nine years ago.
According to your comments I think this amine sump should be replaced by a new steel tank above grade, however none of the problems you described have occurred here.
I have searched on internet and I have found other amine sump made of concrete, so I want to know if concrete is a good or bad design.
I really appreciate your comments, but do you know any literature reference regarding the material selection criteria for this purpose.
Thanks in advance

[Art Montemayor]

Rodolfo:

I still don't know WHICH amine you are storing in your concrete underground tank. I know of no literature reference regarding concrete criteria for this type of application. I doubt very seriously if you would be allowed to do this type of storage here in the USA - either by the operating company or the local environmental agencies.

Maybe other members can volunteer some information regarding this type of application and operation.

Concrete is concrete. The only specification I've found is regarding its structural strength, not its anti-corrosive properties. There are not that many concrete storage tanks around anymore.

One of the important reasons against use of this type of tank that I failed to mention in my prior post is Confined Space Entry. I try to eliminate the need for confined space entry in every design and consulting job that I do. Safety is a big concern with me and I give it priority. I simply will refuse to go into an underground tank to do cleaning and do maintenance. I consider this a very risky and dangerous job and I never expect a worker to do a job that I would not do. That philosophy was taught to me by my first mentor, and it has always been my principal rule in managing production companies and projects. An underground tank has an inherent need for human entry.

[fallah]

Hi,

Just adding a point to Art's valuable explanations:

It is not uncommon to build amine sump drum from CS ( normally LTCS) in underground as a part of relevant closed drain system for collecting amine drains. Of course such drum is to be located in a concrete pit with sand grains inbetween. The drum has a boot for pumping the remained amine out toward next destination.

Fallah

[rodolfoingeniero]

Art,

The amine being storaged in the concrete sump is DEA.
Regards!