Phase Envelopes

[pikadoh9]

Hello, I am working on phase envelopes in Hysys and how to use it to understand how a fluid will behave under certain conditions.

My question is:

Why might knocking out liquids when dropping pressure be bad ?
What about in the fuel gas to a Gas Turbine ? (40 bar supply down to high 20’s in the combustion chamber)
In the case of the fuel gas, how might we get around this problem ?

Why might knocking out liquids when dropping pressure be good ?
What about when we are trying to recover liquids from the gas ?

Can anyone help me?

 

[PaoloPemi]

the phase envelope utility allows you to identify the different states of a fluid (vapor, liquid, solid) in a range of pressures, temperatures etc.

I utilize a different software (Prode Properties, prode.com) which gives me the possibility to work from within Excel or Matlab, but the field of application is the same, typically I do generate a phase envelope to

a) identify the state of the same fluid in different sections of a plant
b) see vapor-liquid, vapor-liquid-liquid or vapor-liquid-solid lines (for example working with natural gas I can calculate water dew point, hydrocarbons dew point, CO2 freezing point etc.)
c) validate results from two/three phase flash, the phase envelope is the best tool to detect errors in flash operations
d) etc.....

if you wish to learn about phase equilibria I can recommend "Phase Equilibria in Chemical Engineering" by Walas

 

[BENSMIL]

Pikadoh,

Liquid formation with drop in pressure can be good or bad based on the end use of the fluid.

In the case of fuel gas to gas turbine, the liquid droplets in the fuel can cause improper combustion , uneven temperature profile in the combustion chamber leading to mechanical damages. For this reason the fuel gas to the gas turbines are often superheated after knocking off the liquid.

regards,
Benoy