Convert hydrocarbon vapor stream to equivalent liquid barrels

[AlanH79]

So I'm new to the oil and gas field, having been in more of a non-technical and unrelated industry for the past 20+ years. So, I'm pretty rusty!

I have a M&E balance for hydrocarbon stream where I'm trying to confirm the calculations to convert a vapor stream to nominal liquid barrels/day. The reason is I'm trying to do a mass balance on a spill back line off the vapor line and my partial output is in barrels after condensing the vapor stream.

The mixture is mostly isobutane, so will just assume 100% to simplify.
Vapor phase:
T = 151.8°F
P = 99 psia
Mol Wt. = 56.23 g/mol
Mass flow = 146,262 lb/hr

Is this as simple as saying that the density of isobutane at 60°F is 563 kg/m3 -> 563 kg/m3 * 2.2 lb/kg / 264.17 gal/m3 * 42 gal/barrel -> 196.92 lb/barrel

Then 146,262 lb/hr * 24 hr/day / 196.92 lb/barrel --> 17,826 barrel/day

Am I missing anything?

 

[pierreick]

Hi,
I got 17787 barrel/day .. same.
563 kg/m3 is the density at 15 C for isobutane (boiling liquid)
Pierre

 

[LittleInch]

I did it in reverse, but got about 17,500 barrels/day of liquid butane, noting that it is only liquid above about 50 psi at 20C.

If in doubt stick to mass - you can't go wrong then.

Actual volume at a higher temp might be higher as density changes quite a bit, but always say at what temp and pressure some of these things are to avoid confusion.

 

[georgeverghese]

At 151degF, sat vap pressure of iC4 is about 148psia > 99psia, so your condensor is a partial condensor, not a total condensor. So the liquid phase volumetric flow will not be 17.8kbd. Otherwise, your simplification that this is only iC4 is too approximate.

 

[shvet]

1. Why asking oil barrels at chem forum?
2. You are trying to convert this stream to a particular oil, correct? Not a hypotetical oil? The ultimate goal is to reference money, not a volume, correct?
There are so many oils, they have a wide range of densities and light ends content.
Why not to find out iC4 content in the reference oil and combine that with the mass flow?

The volume is easy to measure by primitive means, e.g. a rope, so the historically it has been picking for fiscal calcs. The volume is horrible for eng issues, as yours is.

 

[AlanH79]

At 151degF, sat vap pressure of iC4 is about 148psia > 99psia, so your condensor is a partial condensor, not a total condensor. So the liquid phase volumetric flow will not be 17.8kbd. Otherwise, your simplification that this is only iC4 is too approximate.

it should be 100% vapor at this point. I am looking at the equivalent liquid volume after it's completely condensed. But yes, there is some propane, n- butane, iso-pentane in the mixture. I'm just trying to see if i conceptually have the math right, so I can apply it to actual process conditions.

This volume is the feed, then I have 2 streams on the output, one of which has a meter, after the material has been condensed. ... or so i thought. I just realized there is another line that recycles back upstream of the feed meter. So I need to investigate this line to see if I have enough data to estimate its flow rate .

 

[AlanH79]

Hi,
I got 17787 barrel/day .. same.
563 kg/m3 is the density at 15 C for isobutane (boiling liquid)
Pierre

Thank you

 

[AlanH79]

1. Why asking oil barrels at chem forum?
2. You are trying to convert this stream to a particular oil, correct? Not a hypotetical oil? The ultimate goal is to reference to money, not to a volume, correct?
There are so many oils, they have a wide range of densities and light ends content.
Why not to find out iC4 content in the reference oil and combine that with the mass flow?

The volume is easy to measure by primitive means, e.g. a rope, so the historically it has been picking for fiscal calcs. The volume is horrible for eng issues, as yours is.

1. Why asking oil barrels at chem forum?
2. You are trying to convert this stream to a particular oil, correct? Not a hypotetical oil? The ultimate goal is to reference to money, not to a volume, correct?
There are so many oils, they have a wide range of densities and light ends content.
Why not to find out iC4 content in the reference oil and combine that with the mass flow?

The volume is easy to measure by primitive means, e.g. a rope, so the historically it has been picking for fiscal calcs. The volume is horrible for eng issues, as yours is.

1. I thought this was Chemical Engineering forum and I'm a chemical engineer, seemed logical at the time... is there a better forum i should have used? And I guess I haven't looked at the different forum options, as I think I've always ended up in this forum when I've searched topics over the years - sorry!

2. No conversions. Just trying to do a simple mass balance, in = out. I have a meter on vapor stream, there is a recycle line off this vapor stream, which is what I'm ultimately trying to find the flow through. What doesn't go through vapor recycle line is 100% condensed, where i have another meter. ...except, as I alluded to in reply above, I just realized there is also a recycle line off the condensed line.

I don't think I follow the rest of your comment? How do you measure volume of a vapor line with a rope?

 

[AlanH79]

I did it in reverse, but got about 17,500 barrels/day of liquid butane, noting that it is only liquid above about 50 psi at 20C.

If in doubt stick to mass - you can't go wrong then.

Actual volume at a higher temp might be higher as density changes quite a bit, but always say at what temp and pressure some of these things are to avoid confusion.

What do you mean you did it in reverse?

As for temp and pressure - I was just supplying what info I had from the material balance. Unfortunately, the pressure of the equivalent liquid barrels wasn't documented. I'm guessing it was set to some standard condition.

 

[LittleInch]

Barrels of liquid in O&G world is very common or even BOE, just making it similar.

As such this is a simple volume conversion calculation.

 

[shvet]

@lI
I didn't catch the idea.
Do you mean that 1m3 of iC4 @15°C is equal to 1m3 of crude oil @15°C? Or oil storing temp (e.g. -15°C), or unloading temp (e.g. 30°C), or adjusted survey temp (e.g. 20°C)?
We all know what I am talking about.

My idea is - there are so many hidden issues in the volume conversion (besides those have been mentioned above) that the core idea to convert a light end to a crude oil should be reconsidered from the the point of an ultimate goal.

@Alan
Can you share where you have 1'600 TPD of vaporized pure isobutane?
1600 TPD is 600 KTA which is far above the market limit. This would be a new step in petrochem industry evolution. Where do you have such?

 

[LittleInch]

@lI
I didn't catch the idea.
Do you mean that 1m3 of iC4 @15°C is equal to 1m3 of crude oil @15°C? Or oil storing temp (e.g. -15°C), or unloading temp (e.g. 30°C), or adjusted survey temp (e.g. 20°C)?
We all know what I am talking about.

My idea is - there are so many hidden issues in the volume conversion (besides those have been mentioned above) that the core idea to convert a light end to a crude oil should be reconsidered from the the point of an ultimate goal.

@Alan
Can you share where you have 1'600 TPD of vaporized pure isobutane?
1600 TPD is 600 KTA which is far above the market limit. This would be a new step in petrochem industry evolution. Where do you have such?

No. Barrels is simply a volume. There's nothing about making it equivalent to volumes of oil, it's just a different volume measurement at a set temperature.

 

[AlanH79]

@shvet - I'm not sure if all my comments are showing, I think some are still going through approvals. It's not a pure iC4 line, I was just treating as such to simplify the question.

This is refrigeration section of Alky process. I'm at home, so don't have all process variables to reference - but attached is layout i'm reviewing.

My original question was just the first part of the problem I'm looking at. I have a control valve A that needs replaced. There is no data on the valve,[Edit: vendor has no info anymore & we have no info] besides it being a 6" valve. I am trying to get flow rates through it to help spec a new valve.
Today I realized there was also liquid side, valve B, that is recycling back. What i thought was a simple material balance, is now a bit more complicated. We only have ~3500 bpd at liquid FT, so about 80% is being recycled through valve A and/or B. A is used intermittently to help mitigate compressor surge.

 

[shvet]

1. is there a better forum i should have used?

2. Just trying to do a simple mass balance, in = out.

How do you measure volume of a vapor line with a rope?

1/ Petro forum
2/ Mass balance by barrels is definetly a bad idea.
3/ Crude oil volume is measured by a rope

If you want mass balance you should start with mass flow of the crude oil coming in to refining. Then proceed with mass outflows.

Do you know how exactly butane mass flow has been measured? Or 146,262 lb/hr is just an instrument reading?

 

[AlanH79]

Reading is from vortex meter.

 

[shvet]

Vortex meter measures an oscillation of a sensor inside and converts the result to the mass flow depending on fluid parameters (density, viscosity etc.) that have been input to a software by a user. Fluid parameters depend on actual fluid composition and P&T combination.
How have you checked how the real fluid parameters are relevant to been input ones?