Drying of Shell & Tube Heat Exchangers 2

[DK44]

After Hydro testing of Shell & Tube Heat Exchangers, it is required to be dried (on both sides of the Exchanger) thoroughly ensuring no moisture inside, especially within partition chambers on Tube side of the Exchanger.

1. What are the recommended methods.

2. Is drying by blowing Hot Air a recommended method. If so at what temperature the Air is to be blown and for what time. Does it ensure removal of inside moisture completely especially in the partition chambers on Tube side.
2.1 How such Hot Air is created.

Request guidance for assured moisture free drying of these Heat Exchangers.

 

[Trestala]

Just an example: blow hot air (>60 deg.C) for several hours (>4 hours) for both shell side and tube side after draining. Then you measure the dew point at the hot air outlet after drying, and the air should have a dew point several degrees below ambient temperature (e.g. 3 deg. C below ambient).

 

[DK44]

Thank you Raymond.
How do you create this hot air.
If the Heat Exchanger volume is high (say diameter 2000 mm and length 10 m, it takes very long time (more than a day I suppose) to attain the outlet Air Dew point below ATM. In such cases is it necessary to blow Air at higher temp say 100 C or so. How to create such hot Air.

 

[r6155]

Can you do pneumatic test instead of hydro test?

Regards
r6155

 

[David Browne]

I would not pneumatic test this HE unless there was absolutely no way of performing a hydrotest due to the drastic increase in stored energy.

Use an industrial heater fan connected via ducting to the nozzles allowing air to pass through the outlet and run for several hours (>10m long HE).

 

[DK44]

Thank you r6155.
Pneumatic test could be an alternate.
However,due to large stored energy risk, Hydro test, followed by drying is required.

Thank you David.
For that matter, even for smaller size HEX the question remains same.
Can an Industrial Heater, heat the Air to different temperatures and fill & blow the Heat Exchangers of differing volumes?
I think small size of Air outlet to be used to allow hot Air to contact all inside surfaces properly.

 

[MFJewell]

Depending on the quality of your plant/instrument air, you may be able to dry it just by running that through it.

 

[David Browne]

DWARAKAKRISHNA,

Correct. Hot purge the HE allowing the air to flow through outlet. Use a temperature gun to assess outlet nozzle air temperature. Hold at desired temperature for up to 5 hours.

Also if you're the operator, maybe look through the manufacturer's equipment dossiers provided with the equipment to give recommendations for start-up.

Regards,

David.

 

[r6155]

How can you check if dried thoroughly ensuring no moisture?

Regards
r6155

 

[EdStainless]

We use duct heaters, they are meant to be installed into duct work to provide aux heat input. They have a blower and electric heating elements. They are available commercially in the US.

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P.E. Metallurgy, Plymouth Tube

 

[DK44]

EdStainless.
Thank you for your remarks. Can you provide a leaflet / product brochure of the Duct heaters with blower and Electric heating elements.

 

[SnTMan]

Some have adapted an ordinary gas furnace, such as found in your house, to blow heated air thru the exchanger.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[DK44]

Thanks for for the responses and knowledge sharing. Any further thoughts are welcome.