If iron carbonate can pass through filtrations system then in Absorber iron sulfide will form and plug plate heat exchanger rich side then is it practicable to focus on filtration after Absorber and what type of filter will work perfectly to eliminate the black shoe? Thanks again Amine experts
Hello M. Dellil! The easiest way to determine if you will benefit from rich side filtration is to take a sample of the lean and rich. If the lean is clear and clean, but the rich is darker and contains solids, then rich side filtration is probably best for you. The filter should be placed downstream of the flash drum, but upstream of the Lean/Rich exchanger. It’s difficult to find a filter that will always work perfectly for you (especially not having seen your system or the amine itself), but generally, amine systems get better performance from filters designed to form a filter cake (surface filters) with an absolute rated efficiency. A beta-5000 quality filter of 10-25 micron can usually do an excellent job of removing most solids down to very low micron rating.
I have TEG dehydration plant with blackish lean glycol. The feed gas is a sour gas. The dry gas is on spec, the glycol loses also acceptable 1 drum per day. My question is, do the blackish lean glycol due to iron product? We do replace the cartridge filter based on DP and the frequency of repalcsment is around 2 month? Could tou explain this.
Hello sosa Nasution, There are a few things that will turn a glycol black. Solids are certainly a possibility, but considering your filters last 2 months before they see a high enough differential to replace, leads me to believe you are probably not seeing aggressive solids formation in the system. Another potential cause could be thermal or oxidative degradation, usually a result of elevated reboiler skin temperatures or bulk temperatures. This can be checked by running a gas chromatograph on the glycol and looking for the presence of DEG and EG. Because these glycols degrade at normal TEG reboiler conditions, they are the cause of the dark color. Finally, some hydrocarbons can coke on the firetube and potentially cause a darkening of the glycol.
Thanks for the video. Does it then make since to leave some H2S in the lean Amine to promote the precipitation of solids and get rid of them in the lean filter?
Hi Abdulsalam! The residual H2S in the lean solution should be set at a value that allows you to meet your treated gas specification comfortably. Once you start to leave more H2S in the lean solution, the treated gas H2S will also rise, perhaps to unacceptable levels. It would be difficult to leave enough H2S in the solution to form precipitated iron sulfide particles and remain on specification. The problem with trying to increase solids load in the lean solution is that filters are usually placed after the L/R exchanger, meaning rather than producing more solids for the filters to remove, you’d be forming more solids to plug off the exchangers. Definitely not a winning formula. Please let us know if you have more questions!
JJ, it generally means you have hydrocarbon contamination of the amine. Try increasing the regenerator overhead temperature to vaporize it out! Then increase your reflux purge.
Sir, Lean amine filters are plugging with black shoe polish like material very frequently (with in 24 hours after cleaning) so what does this indicate and how can we able to stop?
Increase your regeneration. Answer is in the below video. Please go through the complete video for complete understanding of issue. However answer to your issue is 06:30 onwards ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_vLYEkEsfyw.html
Hello, Nurliana. The sample on the far right is from an amine system, but is not specifically an amine sample. Because of entrainment and possible vaporization carryover from the regenerator column, this reflux water can contain 0.5 to 1.5 wt% amine. In a gas plant, this amine is not an issue, because it provides some corrosion inhibition properties and the reflux is not purged. In a refinery application, amine in the reflux can be problematic, because the reflux is partially purged to the sour water stripper, where the amine ends up in the treated water and can affect the bacteria in the bio ponds. The reflux water sample should be clear and water white, since it is supposed to be water with a small amount of H2S and CO2 (and perhaps ammonia if the system is part of a refinery application). CO2 removal facilities should be simply water with dissolved CO2. The fact it is cloudy usually indicates the presence of hydrocarbon in the reflux loop. It is also possible that excessive amounts of ammonia salts could cloud up the reflux water, but in this case it was a heavier hydrocarbon contamination (BTEX primarily). Yours truly, Michael Sheilan, P. Eng.
If 10 ppm of iron were something acceptable, why would it form this much iron sulfide? In other words, how much of dissolved iron should I allow in my lean amine to not have this much precipitation?
Hello! THEED is an acronym for tris-hydroxyethyl ethylene diamine, which is a diethanolamine (DEA) degradation product found in plants processing CO2 and H2S streams, however, it is primarily related to the degradation caused by CO2 interaction with the amine. Its formation is especially bad in facilities that do a poor job of regenerating the solvent in the regenerator column, sending too much down to the reboiler where high heat flux can drive the reaction. The amount of THEED generated is generally proportional to the quantity of CO2 in the feed gas. DEA plants with low CO2 in the feed (10%) can see values in the range of 5-8 wt%. It is a non-reversible degradation product and tends to increase the corrosivity of the solution. Please let us know if you have any more questions!
