Differential Pressure role in Steam trap selection

[703george]

Good Day Everyone,

Hope all is well.

We have a free float type steam trap (JH7RH-P) with a maximum differential pressure of 2 bar.

What happense if the differential pressure is more than 2 bar and the trap is full of condensate.?
Trap is mechanically designed for 100 barg.

As per the manual, the trap will be in closed position incase of higher differential pressure. (how?)
If the trap is filled with condensate, the float should rise up due to buoyancy and should discharge the condensate through the orifice.I am confused how the trap can be in closed position under high differential pressure and the trap with full of condensate.

Thanks for your time in reading this, and any feedback is ahighly appreciated.

George

 

[mk3223]

Refer to the TLV manual link below for the steam trap operation

https://www.tlv.com/en-us/products/steam-traps/mechanical/high-pressure#2

Basically, the correct selection of the steam trap is based on the how much DP and the required condensate capacity. See the picture animation for the float trap operation.

 

[703george]

Thanks MK3223 for the feedback.
The link is informative.
However it doesnt explain the reason why condensate backup will occur(as mentioned by the vendor) if the DP is more than the designed limit.
My understanding is that the float should rise up regardless of the high DP or high inlet pressure (considering the fact that water is not compressible) and condensate should flow through the orifice.

Thanks
George

 

[LittleInch]

Where are you getting this 2 bar from? Pleas epost the document or the spec as it seems incorrect and is maybe a misreading of the information by someone.

As far as I can see this is either the min operating pressure or the minimum differential pressure, i.e. if the diff pressure is LESS THAN 2 bar it won't work properly, but otherwise it will.

This is a high pressure high temperature unit.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

Op,

the reason why condensate backup will occur(as mentioned by the vendor)

Need to clarify with where it’s from.

 

[703george]

Thanks LittleInch and mk3223 for your time.
The document with all the requested details (such as max Dp is 2 bar, if higher it will lead to condensate backup etc.) is attached for your reference.
Another interesting data is that the capacity of this trap is around 2500kg/hr (very high).

Hope that helps.
Appreciate your thoughts.

 

[LittleInch]

Nothing attached or linked.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[703george]

Sorry LittleInch,
That was a first timer's mistake. Corrected and attached the image of the document.
I used the link in the bottom of the page to upload attachements to Engineering.com

 

[LittleInch]

Makes no sense.

You've only shown a snapshot.

What model is shown in that drawing?

This document below makes no mention and has a graph with variable DP for the model you have.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[703george]

Sorry, I messed that up.

The model is JH7RH-P as you can see it in the capacity chart pasted above.

 

[LittleInch]

Hmmm,

The P version is described as a very high pressure, high temp steam trap, so maybe there's something about the condensate going critical flow, but 2 bar MAX sounds very low.

Maybe it means the diff pressure can be higher, but you hit choked flow and hence don't get more than 4000kg/hr?

Time to call TLV and sak them what's going on and why the P versions of the trap works so differently to the other versions.


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[703george]

Thanks LittleInch for your time.
The steam temperature is around 400C and pressure around 0.8 to 1 bar. Therefore it is very dry? Can it create that much high condensate.

Contacted the vendor, and got a feedback from their sales team. But it was not convincing.Will try to get their technical team if possible.

Kind regards

 

[mk3223]

The steam temperature is around 400C and pressure around 0.8 to 1 bar. Therefore it is very dry?

The superheated steam is typically dry without too much condensate. But, the function of the steam trap may be needed to be covered from the cold system startup which may generate a high condensate flow. You may confirm it with the Process Engineer and Operation for the startup process.

 

[Asisraja D]

If u have time pls try this link

https://www.ayvaz.com/steam-class/7-Required-information-for-Steam-Trap-installation.html

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

 

[FacEngrPE]

The TLV JH7RH-P can be ordered with 3 orifice sizes, the three available pipe sizes can be ordered with any of the three orifices, the trap castings are the same shape for all versions. The -P version is cast from a different steel.

There are two important pressure ratings for any steam trap
Structural pressure rating of the trap body.
Violating structural pressure rating risks rapid unplanned and uncontained disassembly.
Operating pressure limit
The operating pressure limit is always below the structural pressure limit.
The operating pressure limit is the pressure above which the mechanics of the trap can not develop enough unseating force to reliably open the trap seat.
Larger orifices have lower operating pressure limits.

What happens if the differential pressure is more than 2 bar and the trap is full of condensate.?

Trap Structural pressure rating designed for 12MPa.
Per the flow rating graph, The maximum operating pressure with the #80 orifice is 8.0MPa or 80 bar. a DP of 2 bar will not prevent this trap from operating, but the flow with the No 80 orifice is going to be about 100kg/hr. (104 gl/hr).
This flow is valid only if your pipe arrangement is completely correct. Lower DP is more sensitive to back pressure (can be created by flash steam).

There are several datasheets for this trap. I have attached the one with the capacity table.