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#1 Qasem215

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Posted 01 October 2020 - 11:16 AM

Hi,

In a plant, there's a heat exchanger that is suffering from high dP due to plastics getting stuck at the inlet, due to location and space, installing a filter would be a bit difficult.

Has anyone ever heard of using chemicals to dissolve plastics?
I want to use it to remove the plastics and reduced the dP as an online solution.

I know it's a wild idea, but I'd like to see your thoughts too.

Thanks

#2 latexman

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Posted 01 October 2020 - 12:38 PM

This may not be an apples-to-apples comparison to your case, but during emulsion polymerization our reactor walls, agitators, cooling coils, and heat exchangers get "fouled" and gradually build up a layer of solids.  We see a slight increase in dP, but the main issue for us is loss of heat transfer and loss of good temperature control of the reaction.  We clean equipment with a hot caustic wash.  We've been doing this for decades.  We know some of our competitors do similarly.  I get the feeling your situation might be a  bit different but have no detail to verify that.



#3 Qasem215

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Posted 01 October 2020 - 01:23 PM

Thanks for your interesting feedback!

To be honest with you, a large dP in my case is only an issue because it's restricting the flow to most important heat exchanger in the plant, which if the heat removal in it is low, will largely affect all the plant.

It gets fouled with plastics ( cooling tower issue) and i was thinking if it would be possible to clean it using a chemical, your situation is quite different, as I'd like to clean it with something relatively cool ( probably will be done in the winter if this can even work)

But thanks for you reply

#4 breizh

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Posted 02 October 2020 - 06:41 AM

Hi,

Strange that you cannot install a basket filter  at  the suction or discharge of the pump (s) ( 2 in //)  to collect pieces of plastic ( Packing cooling tower) . Can you share with us a PID of your system ?

Breizh



#5 Qasem215

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Posted 03 October 2020 - 06:39 AM

The line is 72 in in diameter, the flow quantity is quite huge. I don't think it would be possible to share the PID, but I'll provide as much information i can.

The cooling tower is forced draft type, the flow is separated to pumps in parallel, there are worries of cavitation if we install a filter before the pumps although i believe if it was changed very often, it wouldn't be an issue.

#6 breizh

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Posted 03 October 2020 - 07:39 AM

Hi,

What about installing a vertical grid ( mesh) at the suction of the pumps . I had such set up on the channel to collect all the rubbish ( plastic coming from the  cooling towers ) to protect the pumps and equipment downstream . 

My experience producing soda ash. 

Breizh 


Edited by breizh, 03 October 2020 - 07:45 AM.


#7 Qasem215

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Posted 03 October 2020 - 08:46 PM

Hi,

Would you happen to have more information about the vertical mesh?

This is my first time hearing of it.


Thanks for your valuable feedback!



Hi,
What about installing a vertical grid ( mesh) at the suction of the pumps . I had such set up on the channel to collect all the rubbish ( plastic coming from the cooling towers ) to protect the pumps and equipment downstream .
My experience producing soda ash.
Breizh



#8 breizh

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Posted 03 October 2020 - 10:44 PM

Hi ,

A simple ppt to explain the principle .

Time to time the grid is cleaned to remove all debris accumulated coming from the CW packing or by the wind  .

Basically it's a mesh installed on a frame similar to a gate . The support is attached to the concrete basins  .

If you want to isolate the basin from the channel you use a plain slide  gate instead of the grid . 

 

hope this is helping you .

Breizh 

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#9 Qasem215

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Posted 05 October 2020 - 10:44 AM

Thank you so much for your insightful input.

I actually made a visit with a colleague to the cooling tower today, he knows more about it than I and he says that there is a mesh that's already available there but it's kind of a big size, and he says that a smaller size might cause a lot of damage if it was chocked

What do you think?

Many thanks

Hi ,
A simple ppt to explain the principle .
Time to time the grid is cleaned to remove all debris accumulated coming from the CW packing or by the wind .
Basically it's a mesh installed on a frame similar to a gate . The support is attached to the concrete basins .
If you want to isolate the basin from the channel you use a plain slide gate instead of the grid .

hope this is helping you .
Breizh



#10 breizh

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Posted 05 October 2020 - 06:50 PM

Hi ,

No data on your existing mesh to support your comments !  The decision  is yours .

You should question yourself about the reasons why the packing is damaged ;

 Performance of the chemical treatment , accumulation of calcium carbonate on the packing due to bad repartition of the water , possibility of ice ( overload ) during winter season , packing less UV resistant  ( shelf life) .

In other words , you should spend more time on site to investigate the root causes of the problems , let you also discuss with the company in charge of the water treatment and consider a maintenance program on the CW .

 

note : Probably good also to open and clean your HX during turn around ; if so ask your cooling tower supplier @ providing treatment to witness the operation .

 

My views

Breizh 


Edited by breizh, 05 October 2020 - 08:47 PM.


#11 Qasem215

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Posted 06 October 2020 - 03:46 PM

Hi,

Unfortunately it's quite difficult to find the cooling tower data sheet, I'm still looking for it.

Thanks for all your comments, they're really useful.

I do believe that instead of complaining about a high dp on the exchanger, there should be a solution to the root cause, but unfortunately it's difficult to change some mindsets.

Really appreciate your feedback!

#12 jayari

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Posted 10 October 2020 - 05:40 PM

I imagine introducing a solvent to dissolve the plastic in a primarily water stream may have secondary effects are unacceptable (e.g. downstream operations being affected, possible environmental impacts). You'll have dissolve this plastic over and over again - it's usually preferable to avoid creating a difficult, recurring maintenance task.Can you show that fixing the root cause is cheaper in the long term? That usually changes minds quick when common sense is in short supply.


Edited by jayari, 10 October 2020 - 05:41 PM.





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