2 replies to this topic

[chemicooool]

Dear all,
I have a total CO2 recovery and recycle system in the N.G based steam-reformer plant. The CO2 from reformed gas is absorbed in a tertiary amine in a packed bed absorber and is stripped off the amine in a stripper. The top temperature of the absorber is 50degC and bottom temperature wil be 75degC. One-third of the absorber from the bottom is insulated. Rest of the surface is kept bare. The absorber MOC is CS. My question is wheather the bare section of isulation needs to be insulated for stable operation or not?

[S.AHMAD]

1. Generally to improve absorption efficiency, you should remove the insulation since absorption is better at lower temperature and high pressure.
2. The reason for insulation at the bottom is for personnel safety. It is common practice to insulate any piping/equipment operating above 60^oC.
3. Instead of using insulation for the bottom section, you can replace the insulation with wire-mesh to prevent skin contact with hot surface.

[Art Montemayor]

Chemicool:

What you write doesn’t make sense or isn’t all of the whole story.

Is this a design project that is still being put together? Or is it an existing operating unit? I seriously doubt it is the latter. My experience in installing and operating steam reformer plants for producing either syn gas or pure Hydrogen questions the type of “amine” that you describe and the temperatures you cite.

If you are truly after “total CO₂ recovery” as you claim (which is a basic design criteria in a steam reformer unit), then a primary amine – such as Monoethanolamine (MEA) or perhaps even DEA – would be the obvious choice for a solution to employ in the CO2 absorber. There are other absorbents that can – and have been – be used; however, you mention the amines. Rather than go into a lengthy and repetitive discourse, I refer you to: “Gas Purification”; Kohl and Nielsen; 5^th Edition; Chapter 2 - Alkanolamines for Hydrogen Sulfide and Carbon Dioxide Removal. There, you will find complete information regarding the use of amines to selectively remove almost 99% of your CO₂. There, you will also find that operating at ambient or even cooler temperatures is what is best for operating your CO₂ absorber – certainly not 75 ^oC (167 ^oF). If this is a specific process, then I would like for you to give us full details on it.