8 replies to this topic

[manuelh]

Good morning.

 

I have a question. 

If I have a main steam pipe and wants to put steam traps every 100 feets.

The pipe will be insulated with fiber glass.

How you select the steam traps or how you know how much condensate runs for every feet of pipe

 

Example:

 

Diameter of pipe: 200m(656.16feet)

Material: Steel(0.0098")of rougness

Pressure:7barg(101psig)

Satured steam171°C(339.8°F)

Mass flow rate 1000kg/hr(2204 lb/hr)

Velocity 2.3m/s(7.55 feets/second)

 

Thanks

 

Manuel

 

[latexman]

The traps will have to handle heat losses during a cold rain or snow or whatever, but will they have to handle start-up (heating up the steel pipe) or will you cover that with an administrative procedure (valves manually operated)?  It kind of depends.

Edited by latexman, 26 December 2016 - 06:53 PM.

[breizh]

hi ,

For your consideration

Breizh

[manuelh]

latexman we cover with the Supervised warmup - method of startup in which an operator manually opens the drain valves on the steam header to drain away all of the warmup condensate.

 

 

Thanks breizh.

 

 

 

One question. QL( heat loss per foot of pipe) is the same that Linear density heat flow(watts/meter)? that you solves if pipe is inside or out of the building, wind velocity, etc?

I haven´t in the condensate formula the H_LV – latent heat of vaporization, Btu/lb so I never can obtain the amount of condensate.

 

Thanks again

 

Manuel

Edited by manuelh, 27 December 2016 - 04:19 AM.

[breizh]

manuel ,

Any steam table will give you the latent heat of vaporization at the temperature considered .As for unit BTU/lb or Kcal/kg or ...just use Google or any unit converter.   

Breizh 

[manuelh]

Thanks again, no problem with conversions. 

 

One question. QL( heat loss per foot of pipe) is the same that Linear density heat flow(watts/meter)? that you solves if pipe is inside or out of the building, wind velocity,convection coeficient etc?

Manuel

[latexman]

Then calculate the heat loss at worst case conditions for 100 feet of pipe.  That's the trap load.

 

You may have two different sizes/models of steam trap - one inside and one outside the building(s), but they may be the same model.  Got to do the calculations and find out..

[Art Montemayor]

Manuel:

 

I've given you my answer in the Spanish Forum.  What Latexman and Breizh are stating are, in specifics, what I've stated there.

 

I've also added that I seldom have gone into the details of a heat transfer calculation for an exposed, insulated steam main.  What I've done, in order to save time and also use existing know-how is to consult with the actual steam trap vendors (Sarco, etc., etc.) who have resources like tables of steam main heat losses at different ambient temperatures and wind velocities.  I used to do these calculations as a junior engineer over 50 years ago, but today's resources are much more accurate and freely available.  No one knows the actual, dependable capacity of a steam trap better than its manfacturer and unless you work for such a manufacturer, you really don't know the recommendable capacities of each model of steam trap.  Leave the recommendations to them.

 

P.S.:  I seriously doubt that your steam main has a DIAMETER of 200 meters!  Basic data should be accurate if accurate answers are required.

[manuelh]

Sorry is lenght.

Diameter 4".

 

Manuel