3 replies to this topic

[Nikolay_]

Hello

 

I do preliminary calculation of tubular heat exchanger. In order to get correction factor is greater than 0.75 I calculated the value of hot stream outlet temperature. Temperature pattern is below.

Cold stream: inlet      30   outlet      160 C

Hot stream:  outlet     90   inlet    225 C

What is maximum allowable temperature difference between cold and hot sides of tubular heat exchangers?

Is it possible to have temperature difference between cold sream inlet and hot stream outlet of 60 C?

I know that there are restrictions of using fixed tubesheet, but I can't find suitable references.

Could you help me to solve this challenge?

 

 

 

 

[Saml]

Then main issue will be differential expansion between the shell and the tubes. So it is mean metal temperature what you need to estimate to define is you can go with fixed tubesheets or U tubes, or floating head, or expansion momega or bellows on the shell.
 
In "Ludwig‘s Applied Process Design for Chemical and Petrochemical Plants, 4th Edition", Appendix M (you can find it online on the publisher site http://booksite.else.../appendices.php) they mention 50°C. However it will deppend on the stiffness of the shell and tubes, material, thermal expansion coefficients, etc, etc. I've been dealing with a exchanger with only 15°C mean metal temperature where this issue was a major one. So beware of that rule of thum. The procedure is well expained there.

[srfish]

Evaluate the mean metal temperature in the most severe conditions  of start up,shut down, clean and foul.

 

TEMA has a section on mean metal temperatures in section RCB-1.4

[Nikolay_]

Hello,

Thank you very much for a valuable references and instructions. I found some equations for verifying the need for installation Lens compensators. I need time to translate them from native language then I'll show you.