SHS (Superheated Steam) Function Block (Siemens)

dikkeleo

Member
Join Date
Oct 2010
Location
@home
Posts
6
Hello,
We have a startup valve, that has to open on startup etc.
We also want to know the flowrate throughe valve.
They told me that in previous projects they used the SHS Function Block from Siemens and that is was locked.
The previous developer is gone, no source codes from these previous projects.

But I have a nice document which says:
calculation for the flow is approximating steam flow through it:
By using steam temperature and pressure and valve characteristics (to be provided along with the valve – it is not linear) while using SHS function block (siemens block).

Who can tell me more about this SHS Function Block?
Thanks in advance.

Regards,
Andre Janssens
 
Do you really work with SHS?

They told me that in previous projects they used the SHS Function Block

Who are “They”? What is their competence (issue understanding)?

SHS Function Block from Siemens and that is was locked.

What mean “that is was locked”?

calculation for the flow is approximating steam flow through it:
By using steam temperature and pressure and valve characteristics

I don't have a single suggestion how the flow can be calculated from these data (at least 2 pressures are needed - differential).
Temperature and pressure are needed to calculate mass flow at a known flow speed.

SHS is quite tricky substance to flow calculation

I think that it makes sense to find out what parameters and at what points were measured in the previous projects.
 
could not find any information on a Siemens function block for what you are suggesting has been used, however, a Siemens FB will be locked to stop people messing with it, this usually means it needs to be paid for. If Siemens has such a function then there should be documentation for it, or it may be that the original supplier have created their own & locked it.
I suggest you reach out to siemens if they have produced such a block.
 
"They" are the customer, a company in the North of Italy, and my employer.
Some details about the Superheated Steam:
40 bar, 400°C, 15t/h, 3212kJ/kg

I couldn't find anything at Siemens also.
I got this from our E&I team:
https://www.spiraxsarco.com/resources-and-design-tools/steam-tables/superheated-steam-region
https://www.mikrora.com/mollier-diagram-for-steam-pdf/

Superheated steam tables "double" interpolation, I think this is what the SHS function block does:
https://www.youtube.com/watch?v=fP_h-iQckqo
But not sure.

I hope somebody can come up with an idea or solution
 
But I have a nice document which says:
calculation for the flow is approximating steam flow through it:
By using steam temperature and pressure and valve characteristics (to be provided along with the valve – it is not linear) while using SHS function block (siemens block).
So, who is the author of this document ? Is it a Siemens manual or FAQ, or.. ?
 
I just talked to an old colleague who is now working for Siemens Netherlands, but he and his colleagues have never heard about this block or something similar for Superheated Steam.
I suspect a previous developer made it him or herselve and put the steam tables in to it and locked the block.
Now we have to go for searching old projects where this block is used.
Thank you all for your help.
As soon as I have found something I will mention it here!
 
Now we have to go for searching old projects where this block is used.

To find something like this

Qm = k * f(valve opening degree) * ΔP^0.5 * P / T
)))

I still recommend that you find out:
- what parameters and at what points are measured in the existing system
- how the setting of the "SHS block" was carried out (with the help of a reference sensor, according to the given flow rates ... or…)
 
Thanks MaxK!

This looks interesting.
Where did you found or get this?
Is this formula complet becuase you added ))) at the end.
Can you provide more information about this formula?

As in:
- The k is a constant factor?
- What is f(valve opening degree)?
- I don't two pressure transmitters, just 1. Thus ΔP is not possible.
- Temperature measurement is available.

Thanks in advance.
 
I have my dad's copy of the 1967 ASME Steam Tables, complete with a large Mollier chart inside the back cover. Search for Mollier on this forum for a funny story, IIRC.

I am on a flight home just now, but I am pretty sure that book Includes coefficients of polynomial formulations for steam properties (enthalpy as a function of pressure and temperature, etc.). My dad ported a Fortran version of same to Basic back in the 1980s (Timex Sinclair 2068 and Quick Basic), so porting to SCL should be straightforward, if tedious.

There are also newer publications of those tables; I think there was one in the 1980s, and there could be newer ones. However any improvements would be small for operational purposes.

I would also expect to find source code online (Github, etc.), which might save time and errors typing in large numbers of coefficients.
 
Search for Mollier on this forum for a funny story, IIRC.

Found it:

"When Dad, with an automotive tech associate's degree from LIATI Farmingdale, interviewed for the GE Test Program for technicians in the 1950s, he was asked what he knew about the Mollier diagram. He said, "I can spell it." The interviewer replied, "That's better than some of my engineers."

Interviewed at a place that did boiler controls as part of their business.

Boss: "Tell me what you know about stoichiometry."

Me: "Never heard of it. Probably can't even pronounce it correctly."

He laughed. I got the job.
 
Is this formula complet becuase you added ))) at the end.

I added ")))" because I'm just kidding

Where did you found or get this?
Is this formula complet becuase you added ))) at the end.

Applying "Bernoulli's equation" for Orifice plate

Qv = C * A * (2* (P1-P2)/ρ)^0.5

Ideal gas law (Molar form)

ρ = M * P / (R * T)

Qm = Qv * ρ = C * A * (2* (P1-P2)/ρ)^0.5 * M * P / (R * T)

k = C * A * (2 * M / R) ^ 0.5

Qm = k * ( (P1-P2) * P / T)^0.5 – for constant orifice area

f(valve opening degree) - mathematical function of the dependence of the orifice area on the degree of opening of the valve

Qm = k* f(valve opening degree) * ( (P1-P2) * P / T)^0.5 – for variable orifice area

I am not too serious about the task because, in my opinion, given the available data, the task is not unsolvable - i.e. all that's left is to kidding. Or someone fill in the gap in my education by showing how enthalpy can be used to calculate flow.
 

Similar Topics

Hi all, i have an application in which i need to read the water level in a 1 1/2" diameter tube that is 24 in. tall. the sensor will be mounted...
Replies
27
Views
1,824
Hi; We installed an orifice plate type steam flow transmitter which configured to give 4-20mA signal correspond to 0-9ton. I given that signal...
Replies
24
Views
5,547
The IAPWS-IF97 steam table is used as a measuring standard for the correlation between steam temperature and pressure. The calculation formula(s)...
Replies
2
Views
1,673
Good day Gents, Does atmospheric pressure have an influence of a boiler steam pressure.
Replies
31
Views
8,470
I have a heating system in a building and the wall heaters which have very hot steam going through the pipes aren't effected when the control...
Replies
2
Views
2,061
Back
Top Bottom