4 replies to this topic

[kaidlut]

Dear forummembers：

 

Recently，one question puzzled me a lot. For SMR plant, if the reform steam carryover liquid drop, can this cause a reformer tube hot band problem? for example: Steam drum demister Or sour water stripping tower demister degradation.

 

As I mentioned in another post, there was steam carrying liquid from the sour water stripping tower several times. https://www.cheresou...tripping-tower/

 

Several temperature thermocouples along the line captured the temperature drop, The temperature at the end is above the saturation temperature, but I suspect there is a measurement blind spot. Is this possible?

Edited by kaidlut, 07 August 2025 - 01:52 AM.

[Pilesar]

In a SMR (steam methane reformer) reactor, the reaction is endothermic. The outside of the tube is heated and the reaction takes place inside the tubes filled with catalyst. The reaction in the tubes absorbs the heat and cools the tube metal. If the reaction in the tubes is insufficient or the heat transfer surface is fouled, then the tube metal more closely approaches the furnace temperature. It may be that process upsets damaged the catalyst which reduced the reaction rate and will require a catalyst change. The tubes will stretch (creep) and thin at an accellerated pace as the metal temperature increases. A weak tube can begin to leak -- adding uncontrolled fuel and flame inside the furnace and resulting in much higher maintenance cost.The feed to the tubular reactor is designed to be distributed evenly among the many tubes. The distributor design is based on all feed being a vapor. If the feed contained slugs of liquid, then the liquid would not have been distributed evenly amongst the tubes.

[breizh]

Hi,

Consider this link:

STEAM REFORMER

Breizh

[astro]

Off the top of my head, I'd expect that the key risk of significant entrained free liquid in the steam used as mixed feed to the SMR is mechanical damage to the catalyst.
General damage (attrition) if bad enough, would reveal as pressure drop. Possibly damage could be sufficiently intense and localised to result in gas maldistribution and reveal as banding.
Again, off the top of my head, I'd expect hot bands to indicate carbon laydown / catalyst poisoning. If boiler water treatment involves a phosphate programme, then carryover might cause poisoning. One to check out.
I'd be looking to dust off some literature for typical hot spot troubleshooting guides.

Edited by astro, Today, 12:06 AM.

[astro]

Refer here for a better technical analysis than my off-the-cuff, in-transit musings above:

https://www.academia..._Reformer_Tubes

 

The plant that I managed years ago employed an all volatile treatment boiler water programme. That's one way to minimise the effects of free liquid carry over by avoiding poisoning. However, if its extreme then mechanical damage is pretty well unavoidable.

 

The link above refers to an example of poor shutdown practice that resulted in steam condensation collecting in the reformer tubes. Easily avoided by diligent procedure to sweep the plant with nitrogen as a final stage in shutting the unit down.

 

Piping design is also highlighted as a potential concern. Deadlegs can collect steam condensate during cooling as part of plant shutdown that is then delivered in free liquid form to damage the catalyst on its next start if pockets are not drain during the preparatory stages of a restart.

 

Give it a read. It's a good piece.

Edited by astro, Today, 12:25 AM.