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Steam Treatment of Activated Carbon Filters

06/30/2009 9:48 PM

Hi,

One of our clients requires steam treatment of activated carbon filters hence, they requested us to install steam pipeline from a reduced steam pressure source (5 bars) to the activated carbon filter tanks that we supplied. We are not quite familiar with this type of requirement. I would like to ask for suggestions on how to design a steam pipeline for the activated carbon filters.

Specifications:

Horizontal ACF 90" dia x 120" shell length

as per customer, the activated carbon will be heated to 80 deg Celcius for 20 mins.

1. Should I use steam trap and return line? the condensate return line is almost 3m above the floor.

Kindly help me on this one. Thanks

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#1

Re: Steam Treatment of Activated Carbon Filters

06/30/2009 11:00 PM

as per customer, the activated carbon will be heated to 80 deg Celcius for 20 mins.

Can I ask why your want to flood the filter?

phoenix911

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#2

Re: Steam Treatment of Activated Carbon Filters

07/01/2009 3:14 AM

Change the carbon. It is easier.

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#3

Re: Steam Treatment of Activated Carbon Filters

07/01/2009 9:21 AM

Here are a couple of statements found on the 'net regarding re-activation:

"In order to re-activate activated-carbon, it must undergo a process called Pyrolysis. (The thermal decomposition of organic material through the application of heat in the absence of oxygen.). To fully re-activate saturated activated-carbon, you must heat it to approximately 1,472 °F (800°C), in a controlled atmosphere of low oxygen concentration to reduce the possibility of combustion. This fact is even stated in the U.S. Army Corps of Engineers – Engineering and Design, Adsorption Design Guide, Design Guide No. DG1110-1-2."

"Reactivation Process ...
1 Drying < 100°C GAC dewatered to 50% of original weight
2 Desorption 100 - 649°C volatile materials driven off
3 Pyrolysis 100 - 649°C heavy organics burnt leaving residue
4 Gasification >>649°C and >>1038°C vapors and residues from previous stages driven out of pores"

While they don't exactly agree (and the second has some pretty sloppy language in it), neither sounds as if heating to 80°C for 20 mins will do much good.

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#4
In reply to #3

Re: Steam Treatment of Activated Carbon Filters

07/01/2009 10:46 PM

the initial activation of carbon requires high temp, low O2. Reactivation can be done by steam or chemicals. Reactivation drives off the adsorbed molecules by replacing them with another, steam, or ionized chemicals in water.

This yields readily to searches.

http://www.google.ca/search?hl=en&safe=off&ei=MR9MSq_ZH4qEtweV3OmtAQ&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=%22activated+charcoal%22+%2Bactivation&spell=1

http://www.google.ca/search?hl=en&q=%22carbon+in+pulp%22+%2Breactivation&btnG=Google+Search&meta=&aq=f&oq=

http://www.google.ca/search?hl=en&q=%22activated+charcoal%22+%2Breactivation&btnG=Google+Search&meta=&aq=f&oq=

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#5
In reply to #4

Re: Steam Treatment of Activated Carbon Filters

07/01/2009 11:36 PM

guys,

They dont intend to reactivate the activated carbon granules. They just want to disinfect/sterilize it periodically by steam treatment. There were numerous technical reports about activated carbon being breeding ground for bacteria due to its porous surface and the organics that it adsorbs becomes the food of the microorganism. hence the periodic sterilization. What I need is a good steam piping for the activated carbon filter tanks.

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#6
In reply to #5

Re: Steam Treatment of Activated Carbon Filters

07/02/2009 2:21 AM

Seems like the only factor to consider is the temperature. Low pressure steam will be just over 100° C - the higher the pressure the higher the temperature so the pressure will be the control (I have known of steam used at such high pressures that temperatures over 250° are possible) I do not see this reactivating the charcoal all - it will be doing is removing contaminants such as dust oil and grease - the sort of rubbish which collects in a normal air conditioner and is generally recycled to no ones benefit. Another subject I believe that air conditioners that can recycle air are the cause of sick building syndrome as they collect all the rubbish. Air conditioners should have a heat exchanger - not a filter.

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#7

Re: Steam Treatment of Activated Carbon Filters

07/02/2009 2:51 AM

joozmax6,

The first thing that you need to do is to find out exactly what the customers requirements are i.e. Sanitization, Bio Burden Control or Sterilization? Depending on the industry these terms may mean different things - however given the 80degC for 20 mins I would suggest that this is a Sanitization application rather than a Bio Burden or Sterilization application. Since the customer has asked for this then they will probably have an idea of what tests they are going to use to prove that it works.

What is the quality of the steam available- plant steam or pure steam etc?

What is the material of construction of the carbon container (rubber, stainless steel, carbon steel etc) i.e can the container withstand the application of steam?

Is this a carbon filter on a water treatment system? (I am just curious)

You may also wish how to remove the carbon fines as it is likely that fines will be produced from the steaming - backwashing the filter may resolve this issue (depends of course on the application for the carbon filter)

Finally you may also wish to consider what instrumentation you are going to use (again this depends on what the customer requirements are and how they will wish to prove your design).

These answers will impact the design of the pipework. Depending on what the customers requirements are (are the requirements the same as the expectations?), there is probably more involved than just running a steam line to the carbon filters and installing a couple of steam traps.

Kind Regards

Mr. W.A Snow

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#8

Re: Steam Treatment of Activated Carbon Filters

07/02/2009 10:02 AM

My two cents...

I assume you are just blasting the steam into the filter bed?

I would suggest that on the bottom/outlet you have a boot or something that will collect condensate and then run either a steam trap or a level control valve to drain water out of the boot. Without this collection point, it will be difficult to control the condensate, in my opinion. Make sure that you can't leave standing water in the filter housing. You may have to worry about flashing across the control valve, where does the condensate go, is it just to a sewer?

Do you think you need to worry about fines in the condensate causing plugging?

On the inlet, do you think you would need a sparger or something similar to evenly heat/sanitize the bed? One method of control on the inlet would be a pressure controller, similar to what another poster has said. The pressure controller would essentially maintain the temperature in the filter equal to the condensation temperature of the steam.

If you need to design the inlet pipeline, there are some standard design requirements like space between traps, expansion loops, etc. that I am not familiar with.

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#9

Re: Steam Treatment of Activated Carbon Filters

07/02/2009 11:15 AM

There is to much missing information to help much. Vapor or liquid application? Recovering adsorbed material? Is steam direct (injected) or indirect (tube-side) heat?

The carbon beds I am most familiar with were in "contaminated" nitrogen service. The adsorption beds were designed to recover organic chemicals from vents before the waste nitrogen was incinerated. The organics were recovered, "cleaned up" and recycled back to the production process.

The process was: the gas stream flows through the carbon beds with a organic analyzer on the inlet and outlet. Cooling was supplied to remove the heat of adsorption. When the carbon was saturated, and break-though occurs they were taken off line and regenerated with steam. The steam is in tubes inside the carbon bed and a vacuum applied to the carbon facilitate the organic release.

If that is the operation, then a steam trap will be needed as well as a pressure regulator and some method to determine when the regeneration operation was complete.

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#10

Re: Steam Treatment of Activated Carbon Filters

07/02/2009 1:08 PM

Hello joozmax6,

Can you say what this Activated Charcoal is used for specific for your set up please?

Is it cleaning water to drink.............

Water to be used in a Factory?

bb

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#11
In reply to #10

Re: Steam Treatment of Activated Carbon Filters

07/02/2009 5:50 PM

Guys,

The activated carbon filter is used for water treatment. It is a horizontal type with a nozzle plate underdrain. Tank material is Mild steel. The customer wants the condensate straight to sewer. Any suggestions on how my piping would look like? I'm quite familiar with the expansion loops. Do I need it here if I want the condensate straight to sewer? Do I still need a PRV, can't I just open the under drain valve while injecting the steam? the under drain pipe is 1".

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