Rajesh,
Here is the method I adopted for this condensate load calculation.
Formula used for Start-up load:
lb/hr=W * (T1-T2) * 0.114 * L (Visit
<a href="http://www.hoffmanspecialty.com/steamsysman.htm">http://www.hoffmanspecialty.com/steamsysman.htm</a>)
Download Steam Trap Engineering Data Manual and see page 21
Where,
W= Weight of pipe in lb/ft (Use 120% of calculated value to allow for fittings)
T1=Steam temperature at saturation in F
T2=Initial pipe temperature at ambient in F (could be assumed as 15 or 20 c)
L=Latent heat of steam at final operating pressure in Btu/lb (Available in steam tables)
0.114 is specific heat of steel or wrought iron pipe.
Generally start up load will be fairly large. If your steam piping system needs to be stopped & restarted more than twice a year, you better to think to return the condensate back to boiler.
Otherwise you better not to design the steam traps for start-up loads. Because of large load traps (considering 1/2 hour as warm-up period) will be flooded and you may have to use multiple traps in parallel.
If you don’t want to recover the start-up condensate, you can instruct the start-up operation guys to open the drain valve upstream of trap station to sewer. In this way you can design your trap for only running load.
Formula used for running load:
C= {A * U * (t1-t2) * E} / H (Visit
<a href="http://www.armstrong-intl.com/products/traps/stapps.php3">http://www.armstrong-intl.com/products/traps/stapps.php3</a>) Download
SteamDistribution.pdf file.
Where
C= Condensate in lbs/hr-foot
A=External area of pipe in Sq. feet
U=Btu/Sq ft/degree temp difference/hr from chart 17-1
t1=steam temp in F
t2=air temp in F
E= 1-Effiency of insulation (you can assume 80% hence 1-0.8=0.2)
H=Latent heat of stem Btu/lb
Trap manufacturers specify the condensate load capacity chart for each of their model. After all the above theoretical calculation make sure that condensate handling capacity of the selected trap is more than the condensate load calculated using above formulas.
There could be slight difference in the condensate load value by using different formulas used by different Vendors. But the basic concept remains same.
Important question is whether you should design the Trap for Start-up load? You should discuss this with operation & maintenence guys before start designing.
For more specific questions write to <a href="/group/PipingDesign/post?postID=hWLItnI0F3J7cJoo4Xua1uLKy-BgKxtMoaIFgiU3mcHQoNumE-lMiXqVl_MA9g5BRMSJWuakvoj4Pg">umesh_kn@yahoo.com</a>
Regards,
Umesh K.N., Sr. Piping Engineer, {Piping Specials},
Alcan Engineering Pty Ltd, Level 3-110, 443,
Queen Street, Brisbane, QLD-4000
<a href="/group/PipingDesign/post?postID=GV2y27yhFwNjj9SnJFpQDhRpO-O9-uMWQLy-1TjRsiHryQHizSwptb2a7vX_gSopUvVm_tA2qFtsa-2twIQnw1U">Rajesh.Balapure@ril.com</a> wrote:
Dear Group members,
We are looking for condensate load calculation for steam traps for the steam main drips.While dealing with different manufacturers ,we are coming out with different numbers,variation being along about 25 to 30%.The load is mainly for startup of the unit.Can group members throw some light on the optimum way to estimate the condensate load.
Regards,
Rajesh V Balapure
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[Non-text portions of this message have been removed] Received on Wed Jul 06 17:27:00 2005
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