10 replies to this topic

[kamranarif]

We have observed exponential rise in pre reformer (at ammonia plant) pressure drop within 10 days. It may me noted that it is gradually increasing daily. As of now it has been increased from 0.4 to 2 kg/cm2.

Detailed analysis revealed no change in catalyst activity and its performance is consistent

 

Please share your experiences on the same

[PingPong]

I would guess that catalyst bed fouling is the most likely cause.

Due to a change in the composition of the feedstock (such as more heavies and/or aromatics, or more ...... other contaminents).

[kamranarif]

Thanks for your response. Would not this also effect the upstream reactors i-e NiMo/ CoMo bed and ZnO bed. It may be noted that no change has been observed in these reactors 

[PingPong]

Prereformer operates at much higher temperature than HDS and ZnO.

 

You should compare the compostions of the original design feedstock, the feedstock before the pressure drop increase, and the feedstock during the pressure drop increase..

[kamranarif]

Please note that no detectable change in gas quality has been observed. You are requested share any relevant literature, that would be beneficial in trouble shooting.

 

Thanks and regards

[rychurek]

Does streams flow rates( steam, recycle hydrogen and hydrocarbons ) are unchanged? Check pressure drop across reformer too.

[kamranarif]

Pressure drop Primary reformer is normal. Streams flow rates have been counter verified and are within design limits.

 

Thanks rychurek

[kamranarif]

New development:

 

We decided to bypass the pre-reformer to check its behavior. After the activity (~2.0 hrs) the pressure drop across pre-reformer reduced from 2.0kg/cm2 to 0.8kg/cm2,. However, it has started increasing again.

Edited by kamranarif, 01 November 2014 - 06:45 AM.

[PingPong]

Could be that the bed expanded a little while being bypassed, resulting in an increase in void fraction, and therefor a decrease in pressure drop. But during renewed operation the bed starts to compact again, void fraction decreases, and pressure drop increases again.

[rychurek]

Are you sure that dp. measurement indication is correct? Is prereformer upstream pressure increase when prereformer dp. Is going up?

[mehdi]

hi dear kamranharif

2 bar delta p is very high that means mor than 70% of catalysy chang to powder

i'm work in ammonia plant but we have not pre reformer so please show me general drawing of your pre reformer

maybe you have blocking in inlet our outlet of device inside of reactor

 

thanks

M.M.A