6 replies to this topic

[shvet]

Hi, forum

I'm in charge of basic design of water treatment for a refinery. Does anybody have information about steam reforming catalyst poisons? As I've found there are several poisons:
- clorine
- arsenium
- vanadium
- phosphates (only phosphates, may be all P-containing?)
What is max allowable poison rates? Any links, articles or manuals would be worth.

And else can anybody share links about reforming catalyst sintering promoters? Is it Ar and/or V or may be any other chemicals?

[ADITYA.DUBEY]

Shvet

 

Sulphur is also poisonous (including the substances you mentioned) for steam reforming catalyst.As far I remember,its conc was maintained less than 10 ppm for safe operation.But it varies depending upon catalyst composition.

Usually manufacturer add some additives in Ni catalyst to make it immune for poisonous substances(upto some conc.)

It will be better if you contact catalyst supply vendor.They have the poison & conc specification for the same.

 

Regards

Aditya

[Saml]

May you please relate how the water treatment relates to the poisoning of the reforming catalyst?

Are you talking about boiler feed water treatment?

[shvet]

Yes, I'm talking about BFW source.

H2O source in reforming reaction is BFW or demi-water, Catalyst poisons come both with feed and steam. Any catalyst poison, for example Cl-, came with BFW to steam reformer boiler will come to be in steam. So many reformer manufacturers limit some ions in demi-water.

I have an unusual source of demi-water - distillator / evaporator and I would like to know:

- which of ions manufacturers usually limit in BFW/demi-water

- what are max limits of this ions

- which type of evaporator eftertreatment stage would be worth - reverse osmosis or electrodialysis or electro deionizer or something else

Edited by shvet, 27 August 2016 - 10:59 PM.

[Saml]

If you use the "VGB Powertech Service GmbH, Guidelines for Feed Water, Boiler Water and Steam Quality" guidelines you should be OK.

 

Salts are not carried into the steam, unless the boiler have liquid carryover problem. An exception is silica that is volatile in high pressure boilers, but the VGB guidelines address this specifically.

 

Nickel based reformer catalysts are quite robust and usually they are changed because of mechanical deterioration (higher pressure drop) or loss of surface because of the operating temperature. Not because poisoning from steam that meets the above guidelines.

 

Of course, any reputable catalyst vendor you purchase the catalyst from (Topsoe, Clariant, Johnson Mattey or Unicat) can also provide a more detailed guideline. 

[shvet]

 

Salts are not carried into the steam, unless the boiler have liquid carryover problem.

 

Doubtful. Even distilled laboratory water has more ions than some vendors specified. For example usual distilled water in laboratory has:

- total dissolved solids <5 ppmw

- Cl- <20 ppbw

- conductivity <0.5 mS/sm@20°C

- pH 5.6-6.4

- SO4- <0.5 ppmw

- NH4+ <20 ppbw

 

So as you can see even conductivity is too high to use distilled (laboratory) water as BFW for high pressure boilers. As far as I know some vendors specifies demi-water with stricter limits of SO4, Cl and conductivity. In my case instead of laboratory distillators I have industrial distillator / evaporator which concentrates waste water. So in this distillator raw water has more contaminants than usually potable water for distillators in laboratory.

Edited by shvet, 28 August 2016 - 10:40 PM.

[Saml]

 

 

Salts are not carried into the steam, unless the boiler have liquid carryover problem.

 

Doubtful. Even distilled laboratory water has more ions than some vendors specified. For example usual distilled water in laboratory has:

 

 

Doubt is a good thing. It moves you to investigate more.

 

Like everything in equilibrium: there is no zero. But for practical purposes, salts don't go into the steam unless there are droplets being carried over.

 

This carryover is never zero but steam meets the intended quality

 

Granted. The places  I've seen that use 600 psig steam (refineries) for H2 production reformers, have ion exchange BFW treatment, that usually produces water one notch above the VGB minimum for that pressure. On ammonia plants reformers, because of the 1500+ psig WHB, they use a higher quality of BFW.  In these places steam quality has never been an issue for catalyst activity.

 

Please be sure that when lab report "less than" they are not just reporting the detection limit.