Insulation of steam pipe

jojo4nb

I have an assignment and don't even know where to start so thats y am asking the experts on here to give me an idea how to go about this:

In a company factory, a steam line has been identified as loosing too much heat. The steam line has a diameter of 254mm ( it may be considered to be thin walled ) and has an overall length of 400mm.

The pipe carries steam directly from a boiler to a high pressure steam turbine and as it leaves the boiler the steam is at a pressure of 40 bar and is dry saturated.

Cost of each metric steam is £50 and that the mass flow rate of the steam is 60, 000 kg/hr.

Which Type of insulation is ideal and What thickness of insulations and their associated cost should be purchased and installed on the steam line?

Any help guys? new to this topic. ...thanks newman

russ_watters

Welcome to PF. 2-1/2" (60mm) is pretty standard for that size pipe.

jojo4nb

Thanks for your input but i will need to show which insulation types and cost and finally calculations Mr, Russ. i will need to prove how i got the 60mm....i Know for a professional like you its just straightforward wen you see the problem but for a novice on such its confusing...i have read and done a few calculation on heat transfer via thin walled, critical radius probem n thick cylinders but this one is beyond my head

jojo4nb

which type of insulation would u recommend Mr. Russ Watters?

Spinnor

What text book are you using for this course? I would start there or in your notes.

russ_watters

Sorry, I missed the part about it being [very] high pressure steam. You'll want at least 3", maybe more.
http://www.engineeringtoolbox.com/pi...ness-d_16.html


Anyway, is this for an actual project or for school? You're asking a lot of questions that are components of the design a paid professional engineer would do, which, if this is a real project implies that you need better engineering support for your project. You need to hire an engineer. And It's not just that I don't want to provide more than a little help for free, it's also due to the risk: you shouldn't be getting such a large chunk of the engineering from an internet forum and I don't want to be held accountable should I give you a wrong answer based on the little bit of information you've provided.

Spinnor

If this work is not a home work problem then experts should be involved, but given that the pipe is less then a meter long the real cost is in the effort to design and install the insulation. To a first order approximation, just insulate the hell out of it, the money for installing lots of insulation is not much more expensive then installing the minimal amount.

xxChrisxx

Pipe lagging? Polyurethane half shells? Cast in place PU/rubber? Depends on how hot the pipe is, what U value is needed? Etc etc etc. What cost are you looking at for this insulation?

If this isn't a project, why aren't you just emailing insulation companies for quotes? Why search on a forum? Thermal insulation suffers rather quickly from diminishing returns when insulating pipes, so cost increases very quickly for a properly engineered solution.

To be honest if it's all dry and not fantastically hot, I don't see why you'd need an engineered solution, as Spinnor said just wrap it up with lagging.

jojo4nb

It is an assignment and Im not asking you to do my assignment with all due respect but i would like a clue as to how to tackle the problem.


here is the scenario Scenario

In a company factory, a steam line has been identified as loosing too much heat. The steam line has a diameter of 254mm ( it may be considered to be thin walled ) and has an overall length of 400m.

The pipe carries steam directly from a boiler to a high pressure steam turbine and as it leaves the boiler the steam is at a pressure of 40 bar and is dry saturated.

Cost of each metric steam is £50 and that the mass flow rate of the steam is 60, 000 kg/hr.

Which Type of insulation is ideal and What thickness of insulations and their associated cost should be purchased and installed on the steam line?

State any assumptions and show calculations


What iv one so far:

Assuming there is no insulation, it becomes newton law of cooling situation: Q=hA delta T

Area can be found i.e P.I x D x L and delta T is (250.33 + 273)k minus (20 +273)K

Nb: steam at pressure of 40 bar has saturation temperature of 250.33 degree C and im assuming the surrounding temperature is 20 degree C.

What i am struggling to find is the convective heat transfer coefficient. "h"

If i find the value of "h" then i could first find the heat loss without insulation then compare that value with Q with insulation.

Thanks
Newman

jojo4nb

To Chris, spinner and watters, Tanks for your input..but i made a mistake with d pipe length it should be 400 meters.

Spinnor

So would that be about 60 metric tons at 50 pounds (British money that is ?) per ton or about 3000 pounds of energy per hour? If so if you only lost 1 percent of energy from the poorly insulated pipe that amounts to 30 pounds cost per hour or about 720 pounds per day (24 hour operation?).

If we can reduce that 1 percent to say 1/2 percent loss than we save 360 pounds a day or about 130,000 pounds per year (assuming 24 hr a day operation, 365 days a year).

The amount of possible savings warrant some expert advice, which you might get for free from an installer of insulation. A large operation may have some experts who might do the calculations for free if they got the job. I would call around, won't cost much. They might know someone (it is their industry) would could do the calculations you want done for several hundred pounds?

Good luck!

xxChrisxx

If this were a real project then you'd get at least some engineering work done for free at quote stage. This is a really simple problem as far as calculating insulation goes, all you need to know is your required maximum heat loss and amount of pipe so you can calcualte a U value.

U value will then give you a required thickness.