GAS-L: Re: LPG and steam reforming

["Jim Bland" <enecon@ozemail.com.au>]

Propane (C3H8) and butane (C4H10) are extracted from oil and natural gas
production.  LPG is a mixture of propane and butane, anywhere from 100%
propane to 100% butane.  The mix depends on the end use and the ambient
conditions.  In southern Australia, for automotive use, you will find that
LPG contains more propane in winter to keep the vapour pressure high for
easy starting, and less propane in summer.

In a typical oil/gas well, there will be some initial separation of oil and
gas at or near the well head.  The oil will contain most of the >/=C5s
(pentanes and heavier).  The gas will contain most of  the <C5s (butanes,
propane, ethane (C2H6) and methane(CH4)).  Further separation of the gases
is done in a gas plant, which will typically have 3 outlet streams:
=    methane (for sale as a fuel),
=    ethane (for sale as a feedstock to ethylene plants, and subsequent
chemical manufacture)
=    propane and butane (for LPG)

Propane and butane or not normally "manufactured".  What you get with your
oil and gas production is what you have to sell.

Methane can be used for chemical manufacture.  The main processes start with
reforming, which is reaction of methane with either steam ("steam
reforming") or oxygen to form mixtures of carbon monoxide, carbon dioxide
and hydrogen (synthesis gas), by such reactions as:

CH4 + H2O => CO + 3H2
CH4 + ½O2 => CO + 2H2

Synthesis gas can be used to make ammonia, methanol, DME, and synthetic
diesel.  Most of the processes use a catalyst which achieves typically 25%
conversion of synthesis gas to chemical product, so there is a need to
recycle the unreacted synthesis gases.  If the synthesis gas contains large
amounts of inert gases such as nitrogen or carbon dioxide, these will need
to be either recycled, with consequent increased compressor power and purge
gas losses, or removed immediately after the reforming step, which is
expensive.

All of the above processes run at high temperature (up to 1000°C - 1800°F)
and pressure (150 bar - 2250 psig), require a massive scale to be
competitive, and are totally unsuited to the scale of biomass gasification
that this list discusses.  A world-scale methanol plant is currently at
least 2000 t/d, and costs about US$250 million.  If this were made from
green wood at 60% efficiency, you'd need about 3500 t/day of wood.  I expect
you could harvest this from a sustainably-managed forest of about 600 square
km (240 sq miles).

I'm not sure whether this helps the discussion, but it should clear up some
misconceptions.

Regards,

Jim Bland

Enecon Pty. Ltd.
Level 2, 35 Whitehorse Rd.,  Deepdene  VIC  3103,  Australia
PO Box 555,  Deepdene DC  VIC  3103, Australia
Tel: +61-3-9817 6255
Fax: +61-3-9817 6455
www.enecon.com.au
----- Original Message -----
From: Harmon Seaver <hseaver@cybershamanix.com>
To: Peter Singfield <snkm@btl.net>
Cc: <gasification@crest.org>
Sent: Thursday, November 21, 2002 2:20 PM
Subject: Re: GAS-L: RE: Gases for domestic cooking


> On Wed, Nov 20, 2002 at 08:12:14PM -0600, Peter Singfield wrote:
> >
> > Dear Paul and listers;
> >
> > "SYNTHESIS GAS in my favorite synthetic gas from biomass, since proven
> > processes exist to make it into methanol, DME, diesel gasoline or
ammonia,
> > all the necessities of our current civilization."
> >
> > In defense of Tom -- you got to look at the "bigger" picture!!
> >
> > At present propane and butane are produced from natural gas by "steam
> > reforming" -- please -- anyone -- correct me if I am wrong!!
>
>
>    Propane is from petroleum, isn't it? LPG -- liquified petroleum gas.
>
> --
> Harmon Seaver
> CyberShamanix
> http://www.cybershamanix.com



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>