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Our amine system circulation rate is 250 m3/hr. Since commissioning we make up losses by adding fresh amine.
1) Please recommend actions taken to check and monitor health of amine system.
2) What is the typical life of DEA 20 WT % after which whole amine is to be replaced ?
3) Do we have to bleed some amine from reflux drum to reduce system corrosovity?
 
Answers
13/10/2010 A: Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
Normally you are measuring in your plant laboratory on a regular basis the strength (in your case about 20%) of the amine solution and the H2S and/or CO2 lean loading. In addition it can be useful to measure the level of Heat Stable Amine Salts, because a too high level of HSAS can affect the capacity of the solvent and can increase corrosion.
It is also good practice to analyse the amine solution on a regular basis in more detail. This is normally done by an outside lab. This analysis can involve details of the HSAS, metals in the solution and degradation products.
There is no limitation on the life on an amine solution. Some solutions have been known to have been used for many years without replacement. Normally "natural" losses takes care of the replacement.
Oil refineries tend to have higher losses than gas plants.
The reflux drum of the regenerator should only hold water. Amine concentration in the overhead/reflux of the regenerator should be very low or not detectable. If amine is present here, there is a mechanical or an analytical problem.
Reflux water is typically purged to the sour water stripper in a lot of amine units in oil refineries. This is to reduce the level of NH3 in the overhead system. Too high levels of NH3 can can result in significant corrosion. At the same time water should made up with steam condensate. This purge/make up is often an overlooked aspect.