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Gas-Filled Vessel De-Pressuring In Aspen Hysys


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#1 Said Salim

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Posted 10 February 2019 - 10:39 AM

Dear All,
I am intending to simulate depressurizing of an LPG-filled vessel in aspen hysys and I want to study the change of the followning with time: vessel pressure, vessel temperature & flow of gas outside the vessel. When I use depressuring tab in hysys it requests an input stream to the vessel while in my case I don't have that. Does anyone came across similar case and give an advice how to simulate.
Note: in my case the only heat input is through ambient

#2 Bobby Strain

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Posted 10 February 2019 - 01:52 PM

Why not provide an input stream with a very small flow?

 

Bobby



#3 Nikolai T

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Posted 11 February 2019 - 01:31 AM

Hello,

 

In Steady-state you should have flow through vessel. Before conversion to Dynamic close all valves.

 

Regards,

Nikolai



#4 Said Salim

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Posted 11 February 2019 - 09:58 AM

Bobby
We want to provide an LPG tanker with let's say 10000 kg capacity to run our flare during total cut of NG supply. It is filled once and I want to estimate how much time it will provide sufficient flow & pressure to flare burners.

#5 Fletch

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Posted 12 February 2019 - 04:02 AM

The input stream is to define the properties/contents and initial conditions of the volume you are depressurising

In your instance, LPG (propane and butane), pressure and temperature.

Flow of this input stream is immaterial (as its a dummy stream) as the depressuring utility works on a fixed volume basis.

 

How is the LPG flow to the flare controlled or limited, control valve or RO?

You then specify this information in the utility, along with the ambient heat input.

You should be set to run.

 

The flowrate from the tanker will be dependent on the pressure in the tanker, the flow will decrease as the tanker pressure is drawn down.

 

You can then look at the resulting flow profile and see at what time the calculated flow drops below your required (sufficient) flow.



#6 AlertO

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Posted 12 February 2019 - 05:01 AM

Hi

 

It seems your system is pressurization, not depressuring?

 

In addition, have you verified your flare burner with your LPG? I asked you because many parameters e.g. pressure, flow and air required, will be changed when you change fuel gas which your existing burner can not on service with LPG fuel.



#7 Sharma Varun

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Posted 12 February 2019 - 06:16 AM

As replied by Fletch you need to define inlet stream with composition, operating temperature & pressure. this is basic step to beiin the simulation utility.

Dear All,
I am intending to simulate depressurizing of an LPG-filled vessel in aspen hysys and I want to study the change of the followning with time: vessel pressure, vessel temperature & flow of gas outside the vessel. When I use depressuring tab in hysys it requests an input stream to the vessel while in my case I don't have that. Does anyone came across similar case and give an advice how to simulate.
Note: in my case the only heat input is through ambient

It that case you need to define vessel dimensions & select correct method of heat transfer. Total surface area is key to heat transfer.

 

 

Bobby
We want to provide an LPG tanker with let's say 10000 kg capacity to run our flare during total cut of NG supply. It is filled once and I want to estimate how much time it will provide sufficient flow & pressure to flare burners.

Again as replied by Fletch the flowrate will be calculated by the utility in HYSIS



#8 runsaep

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Posted 11 March 2019 - 09:55 AM

in the similar Unsim from Honeywell the input stream option is involved only if several e.g. 2 vessels are to be connected. When one vessel, the input stream has not any effect.






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