6 replies to this topic

[aanita]

In a gas processing plant after gas sweetening and dehydration followed by NGL recovery by Turboexpander, we found CO2 content is increasing in NGL. CO2 should go to gas phase. I want to know the possible causes.

[Bobby Strain]

Well, you should look first at the sweetning unit. It should remove CO₂ to the required level.

 

Bobby

[aanita]

Since it is a selective acid gas removal by MDEA, there is always some CO2 in sweet gas. Up to glycol contactor gas spec  normal. I curious whether CO2 absorb in NGL. If yes what percentage and what is the favorable condition. 

Thank you very much.

[PingPong]

It is not clear what you mean by NGL. Is that demethanizer bottoms, or deethanizer bottoms, or debutanizer bottoms, or ..... what?

 

Apart from that, it would require a lot of information for outsiders to understand your specific problem, such as:

- the original design PFD's and heat and material balance, including compositions of all streams,

- the DCS data of the past operation, when there was not yet a problem with CO2 in NGL,

- the DCS data of present operation,where there is apparently a problem with too much CO2 in NGL,

- present composition of sour gas feed, sweet gas from MDEA, demethanizer bottoms, deethanizer bottoms, .... bottoms, NGL product.

 

As I do not think that your company would allow you to post such detailed info, there probably is not much that we can do for you.

[Bobby Strain]

I presume that you have a process simulator. Use it to determine what the CO2 separation is, based on feed analysis. If it doesn't indicate some problem, then you can check for leaks from feed gas to the demethanizer.

 

Bobby

[salman.azim]

NGL is bottom product debutanizer and LPG is top product. i think u should check ur GC analyzer. bcz normally we get CO2 in the overhead of demethanizer.

[kiansafaie]

Dear annita
If you had co2 on ngl fractionation unit, you got in trouble with co2 freezing on cold box, so removal of co2 to low amunt less than 5 ppm is neccesary in upstream acid gas removal unit. Also you could got this amount of co2 in overhead of deC1 column in the bottom you got only co2 in form of COS.
Thanks