How to do Insulation for Stack (chimney)?

[gotothesky]

Dear Sir,

I would like to know a normal practice for Insulation of a Stack (Chimney)!

As you see an above picture, Insulation is applied to inside of a Stack!
I think this way seems to have many benefits!

Anyone who know it well informs whether this application of Insulation for a Stack is normal or not!

I am highly appreciating!

Best Regards,

 

[gotothesky]

With the above way, I am concerned about Radial Thermal Stress due to Temperature Difference between Stack Shell and Air!
If Insulation is applied to Outside of Stack, Temperature Difference between Inside & Outside of Stack can be minimized!
But, Design Temperature of Stack will be increased!

I hope good comments from a engineer who has a good practice.

Regards,

 

[LittleInch]

Love to know what you think the benefits are?

You will need solid insulation. What are you thinking of?

How big? / long?

Flue velocity and temperature?

Unless you have personnel protection issues I would say most flues are not insulated but made our of something which can withstand the flue temperature (unknown).

Much more information needed.

How to deal with joints?

Installation and QA is a bitch for internal linings of any type. Repairs are next to impossible. What's the difference in thermal expansion?


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[horacio Torres]

flue gas temperature is the key factor, normally never is abode 450 °C. Internal insulation is not needed.

Check i at first

Horacio

https://www.linkedin.com/company/lagotuy/

 

[MintJulep]

Well, it's a thing that is done. For example

https://danserinc.com/capabilities-vacuduct/

So I guess that makes it normal.

 

[LittleInch]

Normal only if you've got really really hot gas, prob more than 500C.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gotothesky]

Dear LittleInch,

We can think about Two Thermal Stresses for Stack!

1. Thermal Stress due to Longitudinal Thermal Expansion.
(I don't know exactly! maybe, The load due to Longi. Thermal Expansion increases stress in Stack shell.
Mostly Weight of Stack will be increase thermal stress.)
2. Temperature Difference Stress between inside and outside of Steel Stack in Radial Direction.
( Hot inside of shell is thermally expanded large, but, Outside of shell is done small.)

Without Insulation, Temperature Difference of Stack in Radial Direction will be large.

In Stack Design Code, ASME STS-1–2011
Stress Equations of Thermal Stresses are NOT specified in detail.
But. In code, Thermal stress needs to be considered!

Due to this reason, I am concerned about it!

 

[gotothesky]

Dear MintJulep

I saw an application of Refractory inside of Stack for High Temperature Operation such like a Fired Heater Stack!
(I remember they kept Stack steel temperature being under 80C with Refractory!)

And, I saw application of Insulation inside of stack.
They said "with insulation inside of stack, stack Temperature will keep cold!"
But, I don't know if it is normal practice or not.