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Condensate In Gasoline Vapor Piping

voc condesate pot gasoline vapor

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#1 Max Domingues

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Posted 26 June 2017 - 06:19 AM

Good morning to all.

 

I would like to know the best way to determine (and size) how many condensate will be formed in a gasoline (vapor phase) piping.

 

I have a 6in pipe flowing gasoline vapor (VOC collected). The flow is 1000 m3/h of gasoline vapor.

 

I must to install a condensate pot before the carbon filters and, previously experiences, showed a very small (less 0,5 liter per day) fraction of condensate  formed but, how to mathematical/chemical demonstrate this value? It is possible or it is only empirical?

 

Thank you all in advance.

 

Max

 

 



#2 spchauhan12

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Posted 26 June 2017 - 11:42 AM

Following procedure can help you out:

 

1) based on Pipe line length & Pipe Size for the given flow rate for gasoline Vapor, find pressure drop between pipe start point & End Point

 

segment.

 

2) Find / estiamte pressure drop.

 

3) Find drop in temperature due to pressure loss.

 

4) Check if this condensate gas cools down to below dewpoint Temperature at the operating pressure.

 

5) This means, all condensate can convert to liquid phase based upon feed composition.

 

 

This is related to Hydrocarbon Dew Point for your Condensate & Gasoline Pipe Line. You can have precise results / estimates from Simulation Programme such as Hysis.

 

Regards,

 

SPC



#3 Max Domingues

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Posted 26 June 2017 - 02:23 PM

Dear Mr spchauhan12, thanks for the contribution.

I already simulated this on Hysys just to understand better (or try) the gasoline vapor behaviour.

Attached you can see the print+screen of my simulation.

For 35 Celsius and 1315 bar(a), i already have liquid and vapor phase but it is not what happens on real life. :)

For better understanding, i collect gasoline vapor from truck loading terminal and send it to treat on activated carbon filters.

On my gasoline vapor header, we collect less then 1 liter per week!

What are your considerations?

Thanks again!

Max

#4 Max Domingues

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Posted 26 June 2017 - 02:24 PM

Print+Screen Hysys simulation.

Attached Files



#5 gegio1960

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Posted 27 June 2017 - 01:39 AM

Hi Max.

it seems you have input to the simulator a composition at constant t, p.

the simulator has simply separated L & V phases at that t & p.

this procedure doesn't satisfy your scope but can teach you something, thru questions.

- from where is it taken the composition?

- how t & p have been defined?

- which property package did you use?

several other questions can be elaborated...

good luck!



#6 Max Domingues

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Posted 27 June 2017 - 08:53 AM

Dear Mr Gegio, good morning! Thanks for collaboration.

 

Following are my considerations:

1) Antoine Pack i used

2) Pressure is 200 mbar (maximum allowed on the trucks) and temperature is ambient (25 Celsius)

3) Gasoline composition is a tried to find an average brazilian gasoline 'type C' with 27% of ethanol.

 

 

 

Hi Max.

it seems you have input to the simulator a composition at constant t, p.

the simulator has simply separated L & V phases at that t & p.

this procedure doesn't satisfy your scope but can teach you something, thru questions.

- from where is it taken the composition?

- how t & p have been defined?

- which property package did you use?

several other questions can be elaborated...

good luck!



#7 gegio1960

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Posted 27 June 2017 - 09:39 AM

ok, I'll try to follow your process....

1) there is an incostincency in Pressure: 1315 or 1213 mbara? please clarify

2) you invented a composition for the bulk of the gasoline in the tanks.

3) it produces a vaporization of 44% at 35°C & 1213 mbara. It is too light (or the property package is not adequate)

4) you have to sell (and so, put in the tanks) a stable gasoline that must have a Reid Vapour Pressure below its commercial specification.

5) the gases that flow to the VRU are not originated by evaporation but by the changing volumes in the empty space of the tank (eg by T increase, by level increase created by pumping fresh material in the tank....)

....



#8 Max Domingues

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Posted 29 June 2017 - 07:31 AM

Mr Gegio, thanks again for your contribution.

 

 

1) Sorry my mistake. It is really 1213 as simulation shows.

2) Yes, i tried to create an average gasoline composition based on what i have been facing here.

3) I will try to change the package and see whats happens

4) The recovered VOC at the column will be send to the gasoline tank and mixed with the bulk liquid

5) The gases are generated when the trucks are loading and the estimation of VOC emission is based on AP-42 (USEPA). We have the evaporation of the VOC during this operation and the air already inside the truck and replaced by the liquid during pumping. My total flow of VOC is the sum of this air+voc.

 

I will add a representative figure for better understanding.

 

 

ok, I'll try to follow your process....

1) there is an incostincency in Pressure: 1315 or 1213 mbara? please clarify

2) you invented a composition for the bulk of the gasoline in the tanks.

3) it produces a vaporization of 44% at 35°C & 1213 mbara. It is too light (or the property package is not adequate)

4) you have to sell (and so, put in the tanks) a stable gasoline that must have a Reid Vapour Pressure below its commercial specification.

5) the gases that flow to the VRU are not originated by evaporation but by the changing volumes in the empty space of the tank (eg by T increase, by level increase created by pumping fresh material in the tank....)

....



#9 Max Domingues

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Posted 29 June 2017 - 07:34 AM

A representative figure of URV process.

Attached Files



#10 gegio1960

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Posted 30 June 2017 - 01:27 AM

repetita iuvant :-)

in order to represent the (liquid) gasoline, stored in the tanks and transferred to the trucks, you should reduce the lighter components to obtain a mix that has an RVP very close to the spec of the commercial gasoline.

for exampe,in USA "Depending on the state and month, gasoline RVP may not exceed 9.0 psi or 7.8 psi. EPA provides a 1.0 psi RVP allowance for gasoline containing ethanol at 9 to 10 volume percent" (see https://www.epa.gov/...apor-pressure).

.....


Edited by gegio1960, 30 June 2017 - 01:30 AM.


#11 spchauhan12

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Posted 30 June 2017 - 02:38 AM

Hi Max.,

 

       I have following observations from sketch provided by you:

 

Scenario / case -1 :

 

There is no continuous flow from Tanker to Condensate Pot. This is batchwise operation.

 

In this case you need to assume less than  0.5 litres (x litres) of Gasoline Condensate collected per one tanker operation.

 

Total Gasoline Condensate collected per day,  Y litres= x litres X Total No. of Gasoline Tanker operation in 1 Day

 

Frequency for removal of Condensate in one week = Y litres * 7

 

Consider, design margin 10 % & round off value to get Condensate Pot Capacity.

 

 

Query :

 

 Condensate pot to Vaccum system Line is open at any time?

 

If this is the case, some condensate vapor accumulated in Pot over a period turns into liquid. This condensate Liquid also needs to be considered.

 

Hope this may help you.

 

Regards,

 

SPC






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