Stearm tracer for low pipeline temperature 1

[Gregoryo]

Hello,

I am working on a project on steam tracers design and I am facing a dificulties. I will state the process conditions:

-There is low pressure saturated steam available (~120-130°C)
-The process fluid flowing in the pipeline to be heated is Formaldehyde-52%
-The Formaldehyde temperature must be between 50-68°C

So I have worked with steam tracers before but the process fluid temperature was higher.

Now, it is only possible to heat through low pressure steam, but the steam temperature is too hot.

I do not consider other heating options other than steam tracing. Does any of you know how to precisely size the tracers line and its control system?

 

[pennpiper]

Gregoryo,
1. Why are you limited to "only" Steam and "only" Tracing?
2. Why not other fluids and other methods
3. What size product line do you have?
4. What size Tracer are you currently considering?



Sometimes its possible to do all the right things and still get bad results

 

[Gregoryo]

1. Why are you limited to "only" Steam and "only" Tracing?
It's the company's requirement. Their standards and they have steam available.



2. Why not other fluids and other methods
The company who designs this kind of plant uses steam tracers, so it is possible and currently the most cheap available.

3. What size product line do you have?
The process tube is 2 1/2" 304 stainless steel std 40s

4. What size Tracer are you currently considering?
According to the Standard for steam tracer design I am folllowing I have to use 3/4"

 

[EdStainless]

In temp sensitive cases I have seen people use a secondary fluid.
With a heat exchanger, thermonic mixing valve and a small circulation pump you can deliver fluid that never exceeds 68C.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[mk3223]

IMO, it's difficult to have steam tracing to achieve a tight temperature control. But, try to have a smaller size of the tracing tube, instead of 3/4", which may help to your design. You may need to play around the steam pressure and tracer size to get the required service temperature.
P.S. don't forget the pipe insulation.

 

[bimr]

Steam tracing is not practical at those low temperatures. Consider using electrical heat tracing or a secondary heating fluid as Ed suggests.

 

[georgeverghese]

From Perry Chem Engg Handbook, 7th edn, pg 10-138, the following may be obtained: Steam tracer htc is approx 4.4Btu/hr/linear ft/degF (or 7.6W/linear metre/ degC) for a 1/2inch tracer cemented to the pipe. You can extrapolate this to get you the htc for any other size of tracer. On page 10-137, it says use 1/10th of the value for cemented tracers if you are using bare tracer ( without conducting cement). You should also make some provisions for reduced heat transfer if/when part of the cemented tracer network on a piping segment were to break free from the cement.

Agree, electric heat tracing is much more reliable these days and more suited to heat sensitive materials, if you could use self regulating style electric heat tracing. You'll find this same recommendation in these pages in Perry.

 

[Gregoryo]

Thank you all

I appreciate your tips.

I found something from TLV. It's a temperature control steam trap. I think it is an option to control the temperature.