[Gasification] Syn Gas
Ken Calvert
renertech at xtra.co.nz
Thu Dec 30 17:40:59 CST 2010
John, Well Done! I am with you 100% on using specific terminology. All
that we ever made was Woodgas! Some of it was good. A lot of it was bad!
Ken C.
----- Original Message -----
From: <JBlack9999 at aol.com>
To: <gasification at listserv.repp.org>
Sent: Friday, December 31, 2010 10:54 AM
Subject: [Gasification] Syn Gas
> Like many of you, I have been in the chemical industry for many years.
> It has been my experience that a gas became synthesis gas or syn-gas
> after
> various treatment processes to prepare it to synthesize a particular
> chemical. Prior to preparing it for synthesizing it had other names.
>
> Typically in the chemical/petrochemical industry it was prepared by
> reforming natural gas. After reforming, it was called reformed gas.
> Subsequently, the ratio of hydrogen to carbon monoxide was adjusted
> (shifted) to the
> proper value for the particular product that was being synthesized. That
> gas was called shift gas. The next stage was to remove carbon dioxide.
> At that stage the gas was called syngas, because it was then ready to be
> synthesized into the final product.
>
> In general terms, to synthesize methanol the ratio of hydrogen to carbon
> monoxide was approximately 2:1. For synthetic natural gas it was 3:1 and
> for ammonia, there was almost no carbon monoxide, but there was some
> nitrogen,
> in the ratio of 3 parts hydrogen to one part nitrogen.
>
> Prior to the use of natural gas, coal gas (producer gas) was used after
> suitable preparation and with the use of oxygen. Again it only became
> synthesis gas prior to the final synthesis step. Gas that was used to
> produce
> hydrogen was never called synthesis gas
>
> In my book, synthesis gas is a gas that has been made ready for the final
> synthesis step into a particular chemical, regardless of what is was
> before
> i.e. the gas is used to directly synthesize another chemical product.
> Wood gas is not synthesis gas, but it could become synthesis gas after
> appropriate treatment. If a gas is cleaned and prepared for burning in
> a kiln
> or a boiler, it is fuel gas regardless of composition.
>
> My preference is to call it wood gas (Tom's term) since it is made from
> wood or, if you want to be more generic it is biomass gas but not
> bio-gas.
> As mentioned by others, the latter is usually used for gas that has been
> produced by anaerobic digestion. If you want to be fancy call it
> xylogas.
>
> If the term syn-gas is used in any other way, it becomes too generic and
> wood gas would loose its sense of identity. By some of the definitions
> used in past correspondence, coal gas, biogas, SNG or even ethylene could
> be
> called syn-gas. Let's try to keep our identity by choosing a
> descriptive
> name rather than devolving into a generic descriptor.
>
> There are some excellent descriptions of the various types of gases,
> including synthesis gas, producer gas, blue gas, carbureted water gas in
> the
> "Gas Engineer's Handbook", if anyone is interested
>
> More fuel for the fire.
>
> John
>
>
> Date: Wed, 29 Dec 2010 13:13:35 -0800
> From: Bear Kaufmann <bear at allpowerlabs.org>
> To: gasification at listserv.repp.org
> Subject: [Gasification] A small literature review re: syngas
> Message-ID: <4D1BA47F.4020804 at allpowerlabs.org>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> I looked through some of the papers I have on hand, and extracted the
> interesting parts as they relate to the latest discussion, FWIW:
>
> "Fuel gas can be used directly as fuel in gas burners or internal
> combustion engines and gas turbines. Fuel gas, after purification and
> possibly water gas shift to adjust the H2/CO ratio, can be described as
> a syngas (a mixture of H2 and CO), which can be used to manufacture
> methanol, ammonia, Fischer Tropsch liquids, or hydrogen for use in fuel
> cells (4). The suitability for a particular usage, i.e. the fuel gas
> quality, is determined by the gas composition and the level of
> contamination by particulates, alkali compounds, nitrogen-containing
> components, sulphur and tars (5)."
> from Kalisz, S. et al. Energy Balance of High Temperature Air/Steam
> Gasification of Biomass in Up-Draft, Fixed-Bed Type Gasifier. Int. Conf.
> on Incineration and Thermal Treatment Technologies, Phoenix, Arizona
> (2004).at
> <http://gasunie.eldoc.ub.rug.nl/FILES/root/2004/3265200/3265200.pdf>
>
> "Fast pyrolyzers rapidly (?1 s) heat dry biomass (10% H2O) to ?500?C and
> thereby thermally transform biomass into bio-oil (?60% of mass), syngas
> (?20% of mass), and charcoal (?20% of mass). The energy required to
> operate a fast pyrolyzer is ?15% of the total energy that can be derived
> from the dry biomass. Modern systems are designed to use the syngas
> generated by the pyro- lyzer to provide all the energy needs of the
> pyrolyzer."
> from Laird, D.A. The Charcoal Vision: A Win Win Win Scenario for
> Simultaneously Producing Bioenergy, Permanently Sequestering Carbon,
> while Improving Soil and Water Quality. Agron J 100, 178-181(2008).
>
> "To improve the thermal efficiency and predict the composition of
> syngas, several numeric models have been developed for biomass
> conversion systems."
> from Rogel, A. & Aguill?n, J. The 2D Eulerian Approach of Entrained Flow
> and Temperature in a Biomass Stratified Downdraft Gasifier. American
> Journal of Applied Sciences 3, 2068-2075(2006).
> Comments: Shows a stratified downdraft model with inputs of air and
> biomass, outputs of syngas and ashes
>
> "The term ?pyrolysis? is typically used either for ...[analytical
> purposes]... or for bioenergy systems that capture the off-gases emitted
> during charring and used to produce hydrogen, syngas, bio-oils, heat or
> electricity (Bridgwater et al, 1999)."
> from Lehmann, J. & Joseph, S. Biochar for environmental management:
> science and technology. (Earthscan/James & James: 2009).
>
> "High purity syngas (i.e. low quantities of inerts such as N2) is
> extremely beneficial for fuels and chemicals synthesis since it
> substantially reduces the size and cost of downstream equipment.
> However, the guidelines provided in Table 5 should not be interpreted as
> stringent requirements. "
> "There is more latitude with regard to syngas composition for engine
> combustion than for turbine combustion."
> "To be considered interchangeable with conventional fossil fuels
> (natural gas or distillate oils) and to ensure maximum flexibility for
> industrial or utility applications, syngas heating value needs to be
> above 11 MJ/m3"
> "At temperatures greater than 1200-1300oC, little or no methane, higher
> hydrocarbons or tar is formed, and H2 and CO production is maximized
> without requiring a further conversion step."
> "Biomass gasification is the conversion of an organic...carbonaceous
> feedstock by partial oxidation into a gaseous product, synthesis gas or
> ?syngas,? consisting primarily of [H2 and CO] with lesser amounts of
> [CO2, CH4], higher hydrocarbons (C2+), and nitrogen (N2). The reactions
> are carried out at elevated temperatures, 500-1400oC, and atmospheric or
> elevated pressures up to 33 bar (480 psia). The oxidant used can be air,
> pure oxygen, steam or a mixture of these gases. Air-based gasifiers
> typically produce a product gas containing a relatively high
> concentration of nitrogen with a low heating value between 4 and 6 MJ/m3
> (107-161 Btu/ft3). Oxygen and steam-based gasifiers produce a product
> gas containing a relatively high concentration of hydrogen and CO with a
> heating value between 10 and 20 MJ/m3 (268-537 Btu/ft3)."
> "Table 8. Compositions of Biomass-Derived Syngas" - includes N2 from
> 0-56%, H2 from 5-43.3%, CO from 9-67%, CO2 from 4-40%
> ...
> from Ciferno, J.P. & Marano, J.J. Benchmarking biomass gasification
> technologies for fuels, chemicals and hydrogen production. US Dep of
> Energy NETL (2002).at
> <http://seca.doe.gov/technologies/coalpower/gasification/pubs/pdf/BMassGasFi
> nal.pdf>
>
> "The resulting fuel is a producer gas (a synthesis gas or syngas) that
> consists primarily of varying ratios of hydrogen and carbon monoxide
> (CO)."
> from Mukhtar, S. Manure to Energy: Understanding Processes, Principles
> and Jargon. (2006).at
> <http://repository.tamu.edu/bitstream/handle/1969.1/87462/pdf_2425.pdf?seque
> nce=1>
>
> In short, the usage from the above doesn't appear entirely clear.
> But in general, syngas is often suggested to have been upgraded, or of a
> higher CO/H2/energy content. Syngas is often used to refer to gas
> intended to be used for synthesis of products. Syngas does also seem to
> be used as general term in some cases.
>
> My preferred usage has been to call the gas the air-blown GEK makes
> "producer gas". Wood gas notes that the carbon source was biomass,
> though I don't prefer the term. "Syngas" being made with O2 or steam.
> The problem with the above is it doesn't leave a general catch-all term.
>
> Cheers,
> Bear Kaufmann
> All Power Labs
>
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