Designing a tubebundle for heating a tank, need help 1

[workermonkey]

I'm a young engineer who's been thrown into the shell and tube heat exchanger world. I work for a small fabricator designing simple HX's. I'm trying to design a tubebundle to heat water in a large tank.

I've been given Kern's Process Heat Transfer book as a great reference but i don't posess a copy (yet!). Right now i use B-Jac to design everything but it's less than helpful with this kind of design since the water isn't flowing.

Is there an easy way to do this? i'd rather not spend my time looking up coeffcients and a hundred different numbers. Working in surface area is the easiest but the hardest to determine. I'm always getting info from customers that i can't do much with because i don't want to spend three days trying to design a simple tubebundle.

am i just generally screwed or do i need to hunker down and just punch it out? I'd love to hear from other people who have had some sort of similar experience.

 

[srfish]

When you receive your copy of Kern, turn to the chapter "Streamline flow and free convection".There is an equation for free convection ( also called natural convection) that is for tube bundles. There is also an example for a storage tank.

Good luck

 

[thermcool]

Fundamentals of heat transfer by ramesh shah and Sekulic is also a useful reference for such problems.

 

[Mattysdad]

maybe you should loook aflatplates website. They have a java sizing tool that can be extremely helpful. This an a better way than shell & tube for any application.

http://www.flatplate.com/

http://www.flatplate.com/software.htm

 

[dstavlas]

SHELL AND TUBE HEAT EXCHANGER DESING 1.4.1

 

[WebWizz]

For some of your calculations you can use the thermal calculation routines on

http://www.engineeringpage.com

Regards, Wim

 

[rmw]

You ought to "hunker down" and go through it detail by detail one time so that you can understand what the process is, what the various "coefficients and hundred other numbers" all mean. With an understanding of all lthe interactions of all these factors you will be able to spot when the canned programs spit out garbage.

If you don't understand all the elements that go into the process, you will struggle to make the modern tools work for you IMHO.

rmw

 

[willard3]

rmw:

Well said....
That's why it take 8 years to get an Engineer's license.

 

[Montemayor]

An "amen" to willard3's post and a big star to rmw for the patience, perseverence and experience in stating the obvious and simple truth - once again.

"Is there an easy way to do this?" - of course not! Just take a moment and use common sense. If there were an "easy" way, who would need professional engineers? And who would need engineering forums? No simple "flat plate" website or tube bundle website will solve the problem. Besides rmw's experienced advice, srfish & thermcool are close behind in the basic, smart solution.

The answer is (as always) a basic and detailed understanding of how to apply the science - which is one definition of engineering.

 

[unclesyd]

You mention that this S&T Hx and state the water isn't flowing.
This is not possible, by chance are you referring to a bayonet heater in the tank?

 

[rmw]

UncleSyd,

Based on the wording of the initial post I took it to be a bayonet type heater from the get go.

rmw

 

[darai]

I'm always getting info from customers that i can't do much with because i don't want to spend three days trying to design a simple tubebundle.[/qoute]

if you won't exert yourself doing the simple things,
it might just take you a lifetime to get your work done....

 

[unclesyd]

I'll get you started.
The heater has to fit in a manway, normally the largest, or blind nozzle near the bottom of the tank. Usually the existing blind flange on a tank is too thin so you have to design a tubesheet based on you layout that is also a flange cover.
You have to figure if you want a self supporting bundle or a bundle on support rails, the best. This is all based on the heat load.
You have to have a steam supply, + 20%, and someway to remove the condensate at full steam flow with a properly sized trap.
The tube layout and arrangement is up to you.
You also might want to check for vibration.