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Replacing Demister Pad

demister pad sulphuric replacing

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#1 Kevinyun

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Posted 25 July 2012 - 09:01 PM

Hey Everyone

Just wondering if anyone knew from experience, at which point a demister pad should be replaced?

I've read somewhere that once the pressure drop is 3 times greater then when it was clean was the right time to change it over because it would indicate blockage. Not sure if that was true or not, but some additional information from anyone on this forum would be greatly appreciated

Thanks

#2 fallah

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Posted 25 July 2012 - 11:20 PM

Hi,

As far as i know, if a demister pad became plugged or fouled it can be cleaned, let say, by a pressure washer. If it is excessively plugged it should be replaced with a new one. How excessive is excessive? IMO, there is no fixed value for all conditions/cases. In fact, process conditions will dictate the maximum allowable pressure drop across a demister pad due to plugging or fouling might be different case by case.

Fallah

#3 breizh

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Posted 25 July 2012 - 11:27 PM

Kevin,
demister is generally plugged because of upset or carry over (root cause) during operation . If plugged it needs to be clean . The replacement will be necessary because of mechanical failure not for pluggage unless wrong technology (material ).

Breizh

#4 rabindra

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Posted 26 July 2012 - 10:20 AM

Generally demister pads should be inspected at every shutdown for checking the healthiness. Sometimes demister pads are damaged beyond repair which need for a replacement. Choked demister pads can normally be cleaned unless its for Sulfur Condensers. Demister pads at the outlet of S condensers are either choked with Solid S (hard to remove without damaging the pad) or damaged during hot sweeping (excess air burns sulfur present in the pads).

#5 Kevinyun

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Posted 26 July 2012 - 10:02 PM

So there is no set pressure drop at which the pad needs to be replaced? It needs to be visually checked? Is that what you guys are stating? It's just that we have a pressure gauge installed and found the change in pressure to be 0.3kPa. Therefore, I thought it would need replacing once it reached 0.9kPa which is three times the pressure drop (depending on if it reaches that or not before the next shutdown).

Checking it everytime there is a shutdown is a great idea, but I was just wondering about when we know when to change the pad based on pressure drop across the pad

#6 Padmakar Katre

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Posted 27 July 2012 - 01:01 AM

So there is no set pressure drop at which the pad needs to be replaced? It needs to be visually checked? Is that what you guys are stating? It's just that we have a pressure gauge installed and found the change in pressure to be 0.3kPa. Therefore, I thought it would need replacing once it reached 0.9kPa which is three times the pressure drop (depending on if it reaches that or not before the next shutdown).

Checking it everytime there is a shutdown is a great idea, but I was just wondering about when we know when to change the pad based on pressure drop across the pad


Hi,
Was going through the your query and subsequent comments by our other friends here. I think if you can come up with system details such as service, type of demister (I doubt if wire mesh is recommended in plugging/clogging service) and downstream vapor routine. Additional inputs such as system in which the demister is installed, a phase separator or a column, if phase separator what are the additional internals. Waiting for your inputs.




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