16 replies to this topic

[dhrubabasu2013]

Please tell me the calculation regarding steam flow through a pipe if temperature and pressure is known....in details pls...

[breizh]

http://www2.spiraxsa...sting-pipes.asp

 

*Consider this resource above , you need to know the pressure in two points and the size of your pipe (inlet diameter and length) .

 

**I've attached a spreadsheet (part "B") but probably good for you to read a text book about compressible flow, isotherm or adiabatic (key words) .

 

Hope this helps ,

Good luck

 

Breizh

Edited by breizh, 07 December 2014 - 07:27 PM.

[samayaraj]

Hi Dhrubabasu,

 

Find attached the excel sheet which is used to determine the line size for steam for a given pressure/ temperature or pressure & temperature, flow rate in TPH and allowable velocity. This excel has inbuilt steam data. So you can use the steam properties by using the special function explained in the excel sheet.

 

In the above excel, you can add the length of pipe and other fitting data to calculate pressure drop using darcy weisbach equation provided the pressure drop is less than 10% of initial pressure.

 

 

#Samayaraj

Attached Files

•  steam flow calc by SAM.xls   578.5KB   267 downloads

Edited by samayaraj, 07 December 2014 - 01:12 PM.

[Ajay S. Satpute]

Additional link;

http://www.cheresour...p-correlations/

 

Regards.

 

Ajay S. Satpute

[Bobby Strain]

Samayaraj,

    I am curious. Why did you go to all the time and trouble to develop steam properties in Excel when they are readily available as a library?

 

Bobby

[samayaraj]

 

Mr. Bobby,

 

I don't get what you are trying to say.  I have given a very simple method and I don think its troubling.  The spreadsheet I have provided has built-in steam data already.

 

 

#Samayaraj

[veeky gaikwad]

Samayaraj:

 

How is it used sir ???

 

Which value should  I input?

[samayaraj]

Hi Veeky Gaikwad,

 

Before using the above attached excel, enable macros in the spreadsheet (pop up will come below the formula bar in that click enable). There are various tabs you can see in that, look for "Functions" tab where there are nearly hundred of functions described how to use. For example, if you want to know saturated temperature of steam of at given pressure, enter pressure in any cell (ex. A2), the in any cell type "=Tsat_p(A2)" and this will show you temperature in deg. C. Like that you can calculate various properties of steam for various combination of temperature, pressure, enthalpy, etc...

 

Note: Pressure in bar absolute. You can use these functions in any part of the spreadsheet.

 

#Samayaraj

Edited by samayaraj, 01 January 2015 - 09:30 PM.

[Lapeche]

Dear all,

I have been looking for information related with line sizing for vacuum condensers and among a very few references, I had here found  the excel file “Producing and Maintaining Vacuum” and also this discussion (among many others).

 

The arrangement I am facing is pretty simple, I have a damp valve passing 22.5 t/h of superheated steam (250ºC) from 15.7bar down to 0.25bar (570 torr vacuum), the condenser operating pressure; we have the condensates at around 65ºC. What criteria to use to size the line between the damping valve and the condenser?

 

If I use the recommendation provided in the excel file the velocity would be 150 ft/s (45.7 m/s) but at what steam density? The density of steam under vacuum (0.11 kg/m3) would return a huge diameter.

 

The condenser is inside a ship and I do not have a lot of space available.

Would you please provide some insights about the numbers in the excel file?

 

Thank you.

 

Best regards,

 

Lapeche.

[samayaraj]

Hi Lapeche,

 

First, the steam at 15.7 bar a & 250 Deg. C after pressure reduction to 0.25 bar a need to be desuperheated using condensate to saturation temperature (around 65 Deg. C) before sending to condenser. For saturated steam, the velocity can be limited between 20 to 25 m/sec. You have to consider the steam density at desuperheated condition and is nearly 0.16 kg/m³.

 

 

#Samayaraj

Edited by samayaraj, 01 January 2015 - 09:28 PM.

[Lapeche]

Thank you Samayaraj,

 

still the line diameter would be over 50 inches in order to keep the velocity you are proposing.

Can you recommend a reference other than velocity? bar/km or ρ.v²?

 

Regards

[samayaraj]

Can you recommend a reference other than velocity? bar/km or ρ.v²?

 

Do you mean the pressure drop in bar/km?

[Lapeche]

yes,

thank you.

[breizh]

http://www2.spiraxsa...calculators.asp

 

Hi,

Consider this resource  (steam pipe), on top of above!

 

 

hope this helps,

Breizh

Edited by breizh, 03 January 2015 - 09:47 PM.

[Lapeche]

Hello Breizh,

 

thank you for the link,

my question is about references for the sizing criteria. What value of velocity, bar/km or ρ.v², would you refer to in order to size a line operating at 0.25bara?

 

Regards

[breizh]

Hi Lapeche ,

 

Consider the documents attached to support your work.

Hope this helps

 

Breizh

[Lapeche]

Hi Breizh,

thank you for all this information,

very useful.

 

Regards,

Lapeche