Simulation of Separation Operations (Separator, 3-phase separator, Tank, Component Splitter, Shortcut Column) with Aspen Hysys.

1.      Separator :

Separator allows separating the stream to two phases, vapor and liquid phase   , he works with the gravity separation (phasic separation).

Let us see example how it works, we have a mixture stream (vapor + liquid), this last enter to separator, and it will happen is the vapor phase goes from the top and the liquid from the bottom

First, we have to define the inlet stream (converged), define the outlet vapor stream and the outlet liquid stream (just by written names).

	Stream
T (°C)	97
P (bar)	15,5
Molar flow (kmol/h)	737,96

  about Energy stream, do not define it (because it will eliminate the Principe of separator)

Second, we have to specify the Delta P of outlet vapor (delta p of both, the inelet stream and the vapor outlet) and liquid streams (inlet delta p) , about Volume and Liquid volume ignore them right now because they specified for the dynamic and the type of separator that you could pick the other two separator (tank, 3-phase separator) 

Finally, we get the separator converged

 

2.      3-Phase Separator :

This equipment has same principle of Separator, so he works with phasic separation (gravity separation), for 3 phases, vapor-liquid light-liquid heavy.

First, we have to define inlet streams, let us take example stream contain gas-oil-water.

	Stream
T (°C)	97
P (bar)	15.50
Compositions	(C1-C12) + water
Molar flow (kmol/h)	737,96

 

Second, specify Delta P just like the separator  

Let us see results

     

Interpretation :

We notice there is a lot of water in vapor stream and oil (because it's not fully separation, it's just initial separation), about the heavy liquid (water) we notice it’s perfect. (But in real we treat it again until making sure to minimize hydrocarbons to < 50 ppm).

Finally we get our equipment converged

 

3.      Tank :    

The Tank generally is used to simulate liquid surge vessels, it products two stream, vapor outlet stream and liquid outlet stream.
The Tank has same principle of separator.

       

4.      Component splitter :

Component splitter separates the stream feed to two streams based on the parameters and split fractions that you specify.

We Use it to approximate the separation for proprietary and non-standard separation processes that did not handle elsewhere in HYSYS.

  First we have to define stream inlet (always must be converged), and we have to define the products streams (by writing names), we have to define Energy stream too (by writing name), this last, it is very important because it can be simulated without energy, and here it works like separator.

Second, we have to specify pressures of outlet streams (overhead, bottom), and we have to specify the vapor fraction (PS: vapor pressure varies between 0<……<1, 0 it means it’s liquid phase, 1 means vapor phase and between them it means (liquid + vapor) phase), 

Third, we have to specify the split components

 

This configuration was for one overhead product and one bottom product, but we can make unlimited of inlet streams and we can make unlimited energy streams, we can product unlimited overhead products, let us see example.

    

5.      Shortcut column :

The short cut column is a simple refluxed towers, used for calculate a the vapour and liquid traffic rates the condenser duty and reboiler duty, the number of ideal trays, and the optimal feed location.

The Shortcut Column is only an estimate of the Column performance. This operation can provide initial estimates for most simple Columns

First, we have to define inlet stream (converged), and the outlet streams, and define the energy streams.

Second, we have to specify :

• Light key bottom (means the lightest component in the bottom stream is this component who we have specified)
• Heavy key distillate (means the heaviest component in the overhead stream is the component who we have specified).
• Pressure of condenser and roboiler
• External reflux ratio

After that, we get our column converged we can see a lot of information

•  A minimum numbers of trays (<20,149 this column with this stream cannot work less to 21 trays)
• Actual numbers of trays (52.029 means the number of trays for this this stream is 53 trays).
• Optimal feed stage (29,94 means streams feeds in 30 stage)
• Temperatures of condenser and reboiler
• Rectify vapor ( stripping vapor * reflux ratio)
•  Rectify liquid (stripping liquid * reboiling ratio)
• Condenser and reboiler duty