15 replies to this topic

[Narnia]

Dear all,

I have to calculate the number of steam traps to be required to Connect steam line (40 barg,400 C) to users at distance of about 350 meter away, how steam trap numbers & type to be calculated for this service.Please suggest at your earlist.

Thanks

[breizh]

Narnia,
Take a look at this resource:

http://www.spiraxsar...als.asp#block11

and this one

http://www.swageloke...ces_No.25R2.pdf



Breizh

Edited by breizh, 16 January 2012 - 12:52 AM.

[Narnia]

Above link did not give me quick idea or any rule of thumb for calculating the steam traps numbers,
is there any rule of thumb or calculations to calculate the number of traps required or after what distance interval trap should be provided.

Thanks

[breizh]

Let you contact the vendors like Armstrong, Spirax or Swagelog for more info.

Breizh

[S.AHMAD]

1. I have not seen any rule of thumb on the number of steam trap. Contact supplier as suggested by Breizh.
2. Alternatively, I suggest that you determine the heat loss per m of piping.
3. From the heat loss determine the rate of steam condensation
4. Select the capacity of steam trap which depends on type, size and condensate recovery piping.
5. Determine the number of steam traps required from 3 and 4 above
Hope the above suggestion helps.

Edited by S.AHMAD, 16 January 2012 - 03:58 AM.

[kkala]

For free software about insulation, go to http://en.wikipedia....Pipe_insulation and look at the end of the text, just above references (North American Insulation Manufacturers Association, etc). In my opinion a piping engineer has to be consulted, since number of traps also depends on the route of pipe. This activity is done here by the Piping Dept, probably using empirical rules. Process could specify a steam trap for e.g. the condensate coming out of an exchanger, not for piping.
The heat loss method mentioned in post No 5 is judged to be the base, yet I understand application has difficulties. Condensate should not be high enough to cause slug flow (you hear bang - bang). Condensate is much higher at start up, when pipelines are cold. A steam trap has to be placed at low pipeline point(s) for drain, and probably at pipeline bends (erosion protection). Probably this specific 350 m line has a very simple route (not known), yet a piping specialist has normally practical experience for the case.

Note: "The efficient use of steam" http://www.bookfinde...tle%3Defficient might contain guidelines.

[Narnia]

Dear KKala,

I agree with you,we also follow the same rules,but at this stage i can not go for some designer for piping plan, i have to just estimate the numbers for preliminiry design basis,

In piping route there are some bends about say 10-15 approx, so keeping in view of that & piping length what numbers i will take.

Thanks

[kkala]

http://www.pipingdes...steamtraps.html could have been useful, but a lot of pages "cannot be found" on clicking...anyway further exploration may show something. Same for http://www.armstron...sked-questions , even though reply to query has not been found.
I have never observed steam traps systematically to get some practical knowledge. An experienced piping designer could give preliminary tangible answers. Anyway detail engineering will specify number, location, type; anything anticipated now is probably for cost estimating and can change later.
Below are some thoughts for want of something better.
1. Assume (but first verify) that insulation specification used is based on 2% heat loss, that is non insulated steam pipe would have 50 times more heat loss.
2. Calculate heat losses, as if pipe had no insulation, assuming 0.02*8=0.16 kcal/m2/h/oC, based on 8 kcal/m2/h/oC per http://www.cheresour...insulated-pipe/. Consider the steam saturated (usual superheat of 10-30 oC can disappear under conditions) and estimate condensate created. This should be continually removed from the network.
3. Estimate condensate at start up, when line metal has to be heated to steam operating temperature, and insulation accordingly (rough value for insulation). This condensate has to be drained out not long after creation. Some people increase steam trap capacity per (2) by a factor f=3 or 4 to cover this, we applied it once to a project not implemented.
4. Place small capacity steam traps at low points of line (low points of the pockets), so that the line can be drained. In case of no pockets and uniform line slope, one steam trap at beginning and one at the end may be indicated. Ignore bends in this preliminary stage. Check whether steam trap capacity generously covers the condensate estimated as above, and time of excess draining at start up.
5. Comments on the above are welcomed, since practice may have additional aspects to consider, or even simplifications.

Edited by kkala, 16 January 2012 - 10:33 AM.

[chemsac2]

Narnia,

There are two ways to fix steam trap spacing:

• Rule of thumb - typical recommendation is to install every 30-60 m in steam mains
• Detailed calculation based on condensate load

Attached files can be of help.

Regards,

Sachin Anjan

Attached Files

•  26. Steam_Mains_Trap_Design_Guide.doc   252KB   146 downloads
•  42. Steam_Tracer_Lines_Traps.pdf   251.94KB   138 downloads
•  Steam_Trap.doc   34.29KB   131 downloads

[Narnia]

What will be the type of steam trap on steam line for conditions mentioned in the Post 1.

[Majed.alkhateeb]

Dear Narnia,
as a rule of thumb u need a station every 15 - 25 meters, Usually it is 20 meters for long distances!
and the common size is 1/2" for this application.
For your requirement, you will need the followings:
* Thermodynamic steam traps ; Qty 18 ; Thermodynamic is the best for this application
* isolation valves ; qty 54 ; If you wish to have the best layout for the system
additional accessories:
* strainers ( if the model of the steam trap does not have an inbuilt strainer ) ; Qty 18
* Check Valve ( unless the steam trap modle doesnt require so);qty 18
* sight glass ; Qty 18
* Air vents ( for rapid start up of the system and to avoid water hammering.

if you wish, i can help you in sourcing the above from our Company as we are suppliers for the above.

drop me a line if you wish to have more information, my email is :
Majedut@hotmail.com

Regards,
MAJED AL-KHATEEB
Valves and Steam Specialist

[Parthasarathy]

Thumb rule is 30 meters distance.Where there is change in direction of line provide a boot and a steam trap to be provided. Use a compact type steam trap which some of manufactures recommend as it minimises the field work and leakage of steam in the plant

Attached Files

•  Payback Calculations.doc   21KB   58 downloads
•  PC01 010.jpg   586.17KB   12 downloads

[aanita]

At 40 Barg and 400 ⁰C temperature, it is superheated steam. Do you need steam trap in a superheated steam line?

[Narnia]

yes,on superheated steam line

type & other details will be required

[kkala]

Some notes on the topic, probably useful.
1. http://www.cheresou...of-steam-trap/ deals with similar subject.
2. In post No 8, I had not noticed steam conditions (400 oC, 40 Barg) advised by Narmia, that is 148 oC superheat. Even if calculated heat loss predicts no condensation along the line, steam traps have to be installed to remove condensate at every start-up, when the line is cold.
3. I understand that steam trap type depends not only on the application, but also on the "mentality" of each plant, mainly how much care is devoted to steam traps. For instance, in a fertilizer plant (having worked in 1975-81) steam traps were always leaking. In a big plant area steam traps were replaced by another type, actually being a cylinder ending to a cone with a small hole at the summit discharging to atmosphere. Condensate came out through that hole, and so did steam when there was no condensate; but total steam savings were important in comparison to previous leaking situation.
Then we called that type of steam trap "thermodynamic", but actually it was another type (name not known).
4. The "Efficient use of steam" by Oliver Lyle, http://www.bookfind...le%3Defficient , is remembered to have a list of steam trap types with their pros and cons; but the book is not easily found today.

Edited by kkala, 11 February 2012 - 03:46 AM.

[jrtailor09]

What will be the type of steam trap on steam line for conditions mentioned in the Post 1.

Narnia,

Find below infor for the selection of steam trap.

Steam trap selection shall be as follows:

1. Inverted bucket traps are preferred in high pressure steam services.

2. Thermodynamic steam traps with integral strainers and blow-off connections shall be used for steam tracing.

3. Vacuum or lift traps shall be used for draining condensate from low pressure systems where the available pressure differential is too low for other types of steam traps.

4. Thermostatic traps shall be used for unit heaters and pipe coils not in constant use.

5. Ball float traps (continuous drains) together with an upstream strainer shall be used for a modulating service such as draining condensate from temperature

controlled reboilers, for trapping liquids in gas or air streams, and for venting air or gas from liquid streams.

Regards,

Jatin

Edited by jrtailor09, 20 June 2012 - 01:36 AM.