10 replies to this topic

[neriet]

for a gas plant we wish to include in DCS panel the following properties

-hydrocarbon's dew point
-water dew point
-hydrate formation temperature

these will be calculated from gas compositions (from GC) with a EOS (or different method with equivalent accuracy),
DCS offers limited programming capabilities (only basic scripting) and an external package is required which could be connected to GC and DCS via MODBUS,
the package should be able to calculate all the above properties preferably with a EOS (Peng Robinson),
comments and suggestions are appreciated.

Edited by neriet, 03 April 2013 - 09:53 AM.

[shan]

Do you have a data collecting system such as PI?  Do you need to monitor the data continuously or once a day?  You may obtain dew points and hydrate temperature information by using Hysys per the stream compositions.

[PaoloPemi]

usually different procedures are required for  HC Dew Point, Water Dew point and Hydrate conditions,

for HC Dew Point Peng Robinson should be Ok while for Water Dew point I can recommend GERG 2008 or ISO 18453 (GERG 2004) these have accuracy of 1-2 K,

for Hydrate conditions you may get different results if there is free water (or not), simulators offer different alternatives based on EOS for gas fugacity plus Van Der Waals-Platteeuw for hydrates.

 

If you wish to use MODBUS (or OPC) interface then I can recommend this product

 

http://www.prode.com...hydrocarbon.htm

 

which includes all the features which you need,

hoping this helps,

Paolo

[neriet]

thanks Paolo,
does Prode include the GERG models ?
Which models does Prode include for hydrates ?

Edited by neriet, 03 April 2013 - 12:02 PM.

[PaoloPemi]

you can download the operating manual of Prode Properties,

there is the list of the models available in the different versions,

both GERG 2008 and ISO 18453 are included.

 

For hydrates Prode has three options

 

1) assume water in liquid phase

2) calculate water (amount) in liquid phase

3) solve as VLS (multiphase) equilibria

 

the models are based on CPA (Cubic Plus Association) for gas and liquid phases, Van Der Waals-Platteeuw for hydrate phase

Edited by PaoloPemi, 03 April 2013 - 12:23 PM.

[Mayank Joshi]

Hi all !!
due to some problem in my account i am unable to start a new topic. I had a query , I have a process gas which has steam, the composition of gas is known the pressure of the gas is known , How do I calculate the dew point of steam in the gas?

Composition:-

 

h2   78%

c02   15.4%

co    3.8%

ch4    2.8%

total condensate in process gas -8 m3/hr

Process gas dry basis- 34000 nm3/hr

[Mayank Joshi]

process gas pressure is 21 kg/cm2

[shan]

Steam or Stream?  The composition of steam is 100% H2O.

[PaoloPemi]

please open another thread since your question is not correlated with the original question

[Mayank Joshi]

Steam . I need to know at what temperature the water vapour in the process gas will start condensing

[PaoloPemi]

you cannot solve that, the sum of H2 78% + C02  15.4% + CO 3.8% +C1  2.8% gives 100%,

you do not specify the conditions (t, p) at which the 8 m3/hr are calculated,

from the above data you cannot estimate the amount (mol%) of water,

for a phase equilibria calc' you need to define the composition, then you can solve at specified t,p (isothermal flash) or specified phase fraction (two or three phases equilibria at specified t or p),

by the way for your stream with 78% hydrogen , CO2 , HC and some water you may get large errors with standard EOS,

take care to select a model suitable for hydrogen and other components probably well above Tc (do not forget that freezing point of water is 273.15K)

I Have used Prode Properties for these calcs but care is required for the above mentioned reasons.

If you wish to further discuss this topic I can open a new thread  for you.

Edited by PaoloPemi, 05 April 2013 - 09:18 AM.