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Offline gas_treater

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activated carbon specification (amine unit application)
« on: May 07, 2008, 10:12:38 PM »
Hi all,

I found that 'ash content' and 'iodine number' usually mentioned in the activated carbon product specification. One source mentioned that iodine number is a measurement of activity level (higher number indicates higher degree of activation). Contrary with ash content, ash can reduce the overall activity of activated carbon so higher ash content means lower activated carbon activity.

My question is : If an analysis of an activated carbon product shows that it has a certain iodine number, has the activity represented by the iodine number covered the activity decrease caused by the existence of ash? In example, between two different activated carbon, A and B, A has a higher iodine number than B, but A also has a higher ash number than B. In case if we want to choose activated carbon which has the highest activity, should we consider both parameter (ash content and iodine number) or the iodine number has covered all?

Thank you in advance and best regards

Offline eugenedakin

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Re: activated carbon specification (amine unit application)
« Reply #1 on: May 08, 2008, 07:58:30 PM »
Hello gas_treater,

Quote
My question is : If an analysis of an activated carbon product shows that it has a certain iodine number, has the activity represented by the iodine number covered the activity decrease caused by the existence of ash?

Maybe  ;)  If the ash forms a ash-iodine complex, then it will effect the iodine number.  Its a wild guess to determine the total number of iodine reactive 'ash' in a sample. The general assumption is that the ash is relatively non-reactive.  Usually, ash has been partially covered by carbon - which relates to the activity number.  When applying this in the field, small changes (5-6) are largely ignored. If there is a change from 5 to 50, then this is a signifacent change and should be examined further.

Quote
In case if we want to choose activated carbon which has the highest activity, should we consider both parameter (ash content and iodine number) or the iodine number has covered all?


Usually, the most commonly examined parametes for activated carbon are Particle Size Distribution (Smaller reacts faster), Iodine (Activity level - higher is better), and Tannin number (molecule size - 200-300 is optimum).

I hope this helps,

Sincerely,

Eugene


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Offline gas_treater

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Re: activated carbon specification (amine unit application)
« Reply #2 on: May 08, 2008, 10:28:19 PM »
Hi eugenedakin,

Thanks for the helpful response - as always. I'm pretty sure from the start that you would be the one who answr me question  ;D. Some more question, please?

Some activated carbon forms too much dust and fines so it will need to be backwashed by a certain amount of water at its post loading. Until this time, backwash procedure is not possible to be applied in our unit because of we lack of water supply facilities, especially the water pipeline. So we presupposed our unit for using activated carbon products which are hard enough so they do not forms excessive amount of dust and fines during transportation to our unit and during loading activities.

Firstly, I thought that - beside affected the activated carbon overall activity - the higher ash content will also contribute in the higher fines formation. Will it or won't it? Actually, what will be affected most by the high ash content? Will it affected the foaming risk by providing solid particles in the amine circulation system? If it won't, so probably specify the hardness or abrasion number parameter will be enough.

Best regards and have a nice day.


Offline eugenedakin

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Re: activated carbon specification (amine unit application)
« Reply #3 on: May 08, 2008, 11:13:07 PM »
Hello gas_treater,

Quote
the higher ash content will also contribute in the higher fines formation.

Yes, your right. More fines will be released with a higher ash concentration.

Quote
Will it affected the foaming risk by providing solid particles in the amine circulation system? If it won't, so probably specify the hardness or abrasion number parameter will be enough

Yes, ash could increase the foaming tendency of the amine. One of the most common metals released is Fe2O3 (Rust). Yes, Fe2O3 is quite abraisive in higher concentrations.

I hope this helps.

Sincerely,

Eugene
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Offline gas_treater

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Re: activated carbon specification (amine unit application)
« Reply #4 on: May 10, 2008, 02:24:06 AM »
Hi, eugenedakin!

Thank you very much for the latest answers.

Is there any typical data of ash content for each class of activated carbon material (bituminous, sub-bituminous, lignite, wood, etc...)?

Thank you in advance.

Have a nice day.


Offline eugenedakin

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Re: activated carbon specification (amine unit application)
« Reply #5 on: May 10, 2008, 09:08:04 AM »
Hello gas_treater,

As a general rule of thumb, the best activated carbon is created from trees (waste sawdust). This type has the highest activation with the lowest ash content. Usually, an inexpensive activated carbon is created from coal, but contains the highest level of ash. 

There are exceptions to any rule, and much of the activation depends on the efficiency and type of 'activation' that occurs.

Chuckle, this is an entire area in which a course could be offered  :)

I wish you the best in your selection.

Sincerely,

Eugene
There are 10 kinds of people in this world: Those who understand binary, and those that do not.

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