3 replies to this topic

[GateGuard]

Hello,

I work at a 300mmscfd (2-150mmscfd trains) Amine treater in South, Tx. We are treating H2S and CO2 with 315 GPM of MDEA (Jefftreat MS100). I have about 13 months of experience. Our overall training process is kind of "learn as you go" so I've been aquiring textbooks, articles, and surfing this forum for a while trying to better understand the process. I've been able to research most of my questions but seem to be stumped on this one. A rule of thumb out here is we should keep our "Reflux Temp" (Temperature coming out of our reflux condenser, going into our Reflux accumulator) 10 degrees warmer than our Gas cooler temperature (Gas stream coming out of our Gas Coolers). No one has an explantation why other than "because I said", and I have been unable to find anything online. Per some of my research the only purpose of pumping the reflux back into the top of the regenerator is to cool the top of the regenerator. However, I've read on here that there really isn't an advantage to pumping the reflux back into the regenerator at all that its actually better to use it in other areas of the process. So i'm looking for some insight on ideal Reflux Temperature and why.

 

Simple flow diagram of our process:

Gas-

Inlet Filter Sep--->Amine Contactor--->Gas Cooler--->Amine After-scrubber--->Glycol Contactor--->Glycol After Scrubber--->Residue Sales 

Amine-

Lean Amine Surge--->Amine HP's (315gpm at 1200 psi)--->Amine contactor--->Rich Amine Flash Tank--->Rich Amine Pre-filter--->Carbon Filter       --->Rich Amine After-filter--->Exchanger--->Top of Regenerator--->Regenerator Bottoms/Reboiler (Thermosiphon tube and shell with Hot Oil System)--->Exchanger--->Amine Booster Pumps--->Amine Cooler--->Lean Amine Surge Tank.

 

We refer to the reflux as the steam generated by the reboiler as it leaves the top of the regenerator, then is condensed through the Reflux Condenser/Cooler and dumps into the Reflux Accum. then is pumped back into the Rich Amine feed going into the top of the regenerator.

 

Hopefully I covered everything. Thank you for any input. Feel free to ask anymore questions you have. Thank you.

[apex]

There seems apparatently no reason for this. But to understand better I need detailed pfd with operating conditions & composition of the feed gas. I also have similar units with processing capacity of 5-6 mmscmd which we are sweetening with MDEA. 

[Pronab]

There is no such thumb rule to maintain in reflux temperature. Normally it should be 40 to 45 Deg C. Too much low temperature in reflux zone can form of Ammonium carbamate. However there is a thumb rule to maintain 5 Deg C higher gas inlet temperature than MDEA temperature to avoid Hydrocarbon condensation in MDEA Contactor, which unless foaming will occur.

We are operating 3 sour gas sweetening plant using MDEA of 500 mmscfd capacity each.

A lot of literatures are available in the net.

www.bre.com and then read their technical articles.

 

Best of luck.

 

 

[Art Montemayor]

Gateguard:

 

Are you a degreed engineer - preferably Chemical?  This is important to know if we are to explain how the process is supposed to work, and you are able to understand what we explain.

 

I'm probably the guilty party that has written many times of the uselessness of pumping back a condensed weak water solution of amine back into the top of an acid/sour gas stripper and calling it a true "reflux" stream.  I can prove that such an operation is NOT a reflux for the stripping operation, using simple Unit Operations calculation steps and nothing more.  In all the years I have been preaching this fact, no one has challenged me on this claim and I have to go to my grave waiting for anybody to prove otherwise.

 

What you "describe" with words does not suffice as an engineering explanation of your MDEA sour gas removal unit.  We need a P&ID - which you probably have, but are not offering it as your description of the unit in question.  If you can't issue a copy of the P&ID, then draw a detailed sketch that we can read and understand - preferably on an Excel spreadsheet.  Even a flow diagram would help to give an intelligent answer to your query.  But we need a basis to point to, while we explain how the process works and why some engineering companies continue to pump back condensed weak solution condensate into the Stripper top and call it “reflux"”.

 

Await your reply with your submittal.