3 replies to this topic

[asade abiodun]

Good day All,

I am involve in developing a conceptual design proposal for of a gas plant which would have LPG as product.

A model was developed using HYSYS as shown in the attached document. The attached document shows that propane and mixture of i-butane/n-butane from the De-propaniser and De-butaniser respectively is combined inside a splitter model to obtain pure component of propane and n-butane at a ratio of 30:70 respectively.

I need to confirm if LPG is a mixture of propane and n-butane only OR a combination of propane and (mixture of i-butane and n-butane).

If only n-butane is required in the LPG, what equipment or design principle can be used to split i-butane from the n-butane component from the De-butanizer gas stream?

I appreciate comments and reviews from you all.

Thanks for your anticipated cooperation.

Regards

Attached Files

•  LPG Production.doc   159.5KB   54 downloads

[kkala]

No, LPG is not a mixture of propane and pure n-butane, it can contain the isomer of i-butane (but any upper limit of it in the specification is not known to me), as well as other hydrocarbons. See LPG specification at http://www.nationalg...ecification.pdf, though it does not concern the 30/70 mixture. Also http://www.c1energy....troleumGas.aspx to see hydrocarbons involved. Or http://pirun.ku.ac.t...4754090/LPG.pdf. Hope it helps a bit.

[paulhorth]

Asade,
I agree with Kkala, LPG contains propane and both n-butane and isobutane. Since in your flowsheet, you have split the propane and the butanes in two columns, you can blend these two streams to make any preferred LPG mixture, with the surplus being disposed of somewhere, or you can sell them separately (if you have the necessary storage and export facilities for the two products).
On the HYSYS flowsheet, the component splitter is redundant, I do not see its function. I have designed several gas plants producing propane,and butanes and have never seen or needed this feature.
You have three products: propane, mixed butanes, and C5+ condensate.These are the output of the flowsheet. Each product would have to meet a commercial spec covering vapour pressure, density, percent impurities, etc.
You can combine the propane and the butanes to make a LPG stream if you want the mixture physical properties to check against your customer's spec(density, vapour pressure etc).

Paul

[Fire on dire]

Thats right,
LPG has different specs every where but famous is 30/70 or some times 60/40 C3 and n-C4 and i-C4.
But important is u need to check the specs result of both LPG and Condensate streams.
Check weathering of LPG and RVP of condy. both should should meet the required sepcs.
as well as sales gas HCDP.