4 replies to this topic

[Victor_process_Engineer]

Dear colleagues,

 

I am working on Sulfur guard bed vessel to capture any trace of sulphur downstream of stripper (upstream of Isomerization unit and CCR).

 

There are two sources of naphtha at the refinery, so two options of bed installation were considered:

1. Individual bed on each naphtha stream 

2. One common bed

 

Based on the CAPEX of the vessel, it was decided to proceed with one common vessel.

However, it was later found out that the overall adsorbent volume increased by 30-40% when one vessel was installed as compared to individual installation, therefore this second solution seems to be not cost effective now as the cost of adsorbent is very high.

After discussion with the Licensor, it was found out that apart from superficial velocity and contact time (or adsorbent capacity), there is an additional requirement for H/D to be not less than 2 due to hydraulics.

My assumption is that these criteria are used to ensure uniform flow distribution and avoid channeling.

 

Is it possible to use lower H/D ratio (close to 1.5) and keep running bed smoothly? Maybe some additional distributional tray will help at the feed inlet

Kindly share your experience regarding this issue.

 

Please note that the same criteria were found in another well-known Licensor for activated carbon filter. 

[breizh]

Hi,

Follow the licensors, their comments are based on experience.

Regarding your suggestion to install distributors, how will you replace the catalyst? additional cost for distributors, for additional manholes!

My 2 cents,

Breizh

[Pilesar]

Discuss with the licensor expert. If hydraulics is the issue, then consider whether extended layers of inert media such as support balls would resolve the concern.

Edited by Pilesar, 28 February 2025 - 06:12 AM.

[Victor_process_Engineer]

The Licensor doesn't want to elaborate on this, what is behind hydraulic. I would like to know at least general reasons for that.

You are right maybe additional manhole will be required; however, it is still reasonable.

The price of the adsorbent is unexpectedly high, even when compared with the main catalyst of the process NHT or Isomerization.

 

 

Hi,

Follow the licensors, their comments are based on experience.

Regarding your suggestion to install distributors, how will you replace the catalyst? additional cost for distributors, for additional manholes!

My 2 cents,

Breizh

[Victor_process_Engineer]

Discuss with the licensor expert. If hydraulics is the issue, then consider whether extended layers of inert media such as support balls would resolve the concern.

The Licensor doesn't want to elaborate on this, what is behind hydraulic.

There are 300 mm of inert balls above and below adsorbent.

Did you face such problem in your experience?

 

I agree there is a logic in replacing the additional volume of the catalyst with inert balls if the problem is only in the hydraulics. I will raise this option to Licensor