×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Tank Heater Rules of Thumb

Tank Heater Rules of Thumb

Tank Heater Rules of Thumb

(OP)
I was wondering if anyone had some general rules of thumb for design of insertable tank heaters especially in regards to quantifying/identifying required heat loads. I have looked at examples that Tranter offers and got a few ideas...

I am faced with replacing an existing heater in an existing tank with no past engineering calcs to justify the size. It has been suggested that we decrease the length of the tubes by 10% due to tube availability (bayonnet U-bend type heater). I am just trying to put together some technical backing to whatever we decide to do.


RE: Tank Heater Rules of Thumb

I'm not sure about rules of thumb.  

Sizing a tank heater will depend on the heat losses from the tank, eg. temperature maintenance, as well as any heat loads associated with bringing fresh fluid entering the tank from an initial temperature to the final temperature.

You really just need to work through the numbers.  In addition to Tranter, Brown Fintube is another company you may want to talk to.

RE: Tank Heater Rules of Thumb

dogbertcountry2:

You say you're looking for rules of thumb for tank heaters.  If so, I wouldn't worry about a 10% difference in heat transfer area making a difference in the results.  Such a "rough" device would normally have 25 -50% contingency due to a lot of unknowns - as TD2K implies.  A lot of the heat transfer efficiency and rate will depend on the convection currents in the tank: with an agitator these will increase dramatically; with heavy, viscous and static liquids these will be poor.

I would use the same heater area as the existing - if this has proven to be historically sufficient for what you need.  If need be, I could increase the efficiency by hooking up a recirculation pump with an eductor to increase convection in the tank and achieve mixing.  I could also employ a suction heater: a bayonet-type device which is connected to the suction of your tank's pump-out/pump-around pump.  These devices are much more efficient than the conventional immersion types because they use the convection current created by the pump's suction.

The rules of thumb always involve:
1. Keep the heating elements off the bottom and out of any precipitated sludge or solids in the tank; this reduces corrosion and heat transfer fouling;
2. Keep the tank well mixed; an agitator is great - but expensive and maybe prohibitive; a pump-around may be possible;
3. Use heavy gauge tubes/pipe for the element or coil in order to reduce possible leaks into the tank, causing contamination.
4. Slope your tubes/coils well enough to ensure ready and easy condensate drainage; this avoids condensate hammering inside the element.

I hope these help.

Art Montemayor
Spring, TX

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources