Very well explained and I am in full agreement with all the definitions.<br><br><div class="gmail_quote">On Fri, Dec 31, 2010 at 3:24 AM, <span dir="ltr"><<a href="mailto:JBlack9999@aol.com">JBlack9999@aol.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Like many of you, I have been in the chemical industry for many years.<br>
It has been my experience that a gas became synthesis gas or syn-gas after<br>
various treatment processes to prepare it to synthesize a particular<br>
chemical. Prior to preparing it for synthesizing it had other names.<br>
<br>
Typically in the chemical/petrochemical industry it was prepared by<br>
reforming natural gas. After reforming, it was called reformed gas.<br>
Subsequently, the ratio of hydrogen to carbon monoxide was adjusted (shifted) to the<br>
proper value for the particular product that was being synthesized. That<br>
gas was called shift gas. The next stage was to remove carbon dioxide.<br>
At that stage the gas was called syngas, because it was then ready to be<br>
synthesized into the final product.<br>
<br>
In general terms, to synthesize methanol the ratio of hydrogen to carbon<br>
monoxide was approximately 2:1. For synthetic natural gas it was 3:1 and<br>
for ammonia, there was almost no carbon monoxide, but there was some nitrogen,<br>
in the ratio of 3 parts hydrogen to one part nitrogen.<br>
<br>
Prior to the use of natural gas, coal gas (producer gas) was used after<br>
suitable preparation and with the use of oxygen. Again it only became<br>
synthesis gas prior to the final synthesis step. Gas that was used to produce<br>
hydrogen was never called synthesis gas<br>
<br>
In my book, synthesis gas is a gas that has been made ready for the final<br>
synthesis step into a particular chemical, regardless of what is was before<br>
i.e. the gas is used to directly synthesize another chemical product.<br>
Wood gas is not synthesis gas, but it could become synthesis gas after<br>
appropriate treatment. If a gas is cleaned and prepared for burning in a kiln<br>
or a boiler, it is fuel gas regardless of composition.<br>
<br>
My preference is to call it wood gas (Tom's term) since it is made from<br>
wood or, if you want to be more generic it is biomass gas but not bio-gas.<br>
As mentioned by others, the latter is usually used for gas that has been<br>
produced by anaerobic digestion. If you want to be fancy call it xylogas.<br>
<br>
If the term syn-gas is used in any other way, it becomes too generic and<br>
wood gas would loose its sense of identity. By some of the definitions<br>
used in past correspondence, coal gas, biogas, SNG or even ethylene could be<br>
called syn-gas. Let's try to keep our identity by choosing a descriptive<br>
name rather than devolving into a generic descriptor.<br>
<br>
There are some excellent descriptions of the various types of gases,<br>
including synthesis gas, producer gas, blue gas, carbureted water gas in the<br>
"Gas Engineer's Handbook", if anyone is interested<br>
<br>
More fuel for the fire.<br>
<br>
John<br>
<br>
<br>
Date: Wed, 29 Dec 2010 13:13:35 -0800<br>
From: Bear Kaufmann <<a href="mailto:bear@allpowerlabs.org">bear@allpowerlabs.org</a>><br>
To: <a href="mailto:gasification@listserv.repp.org">gasification@listserv.repp.org</a><br>
Subject: [Gasification] A small literature review re: syngas<br>
Message-ID: <<a href="mailto:4D1BA47F.4020804@allpowerlabs.org">4D1BA47F.4020804@allpowerlabs.org</a>><br>
Content-Type: text/plain; charset=UTF-8; format=flowed<br>
<br>
I looked through some of the papers I have on hand, and extracted the<br>
interesting parts as they relate to the latest discussion, FWIW:<br>
<br>
"Fuel gas can be used directly as fuel in gas burners or internal<br>
combustion engines and gas turbines. Fuel gas, after purification and<br>
possibly water gas shift to adjust the H2/CO ratio, can be described as<br>
a syngas (a mixture of H2 and CO), which can be used to manufacture<br>
methanol, ammonia, Fischer Tropsch liquids, or hydrogen for use in fuel<br>
cells (4). The suitability for a particular usage, i.e. the fuel gas<br>
quality, is determined by the gas composition and the level of<br>
contamination by particulates, alkali compounds, nitrogen-containing<br>
components, sulphur and tars (5)."<br>
from Kalisz, S. et al. Energy Balance of High Temperature Air/Steam<br>
Gasification of Biomass in Up-Draft, Fixed-Bed Type Gasifier. Int. Conf.<br>
on Incineration and Thermal Treatment Technologies, Phoenix, Arizona<br>
(2004).at<br>
<<a href="http://gasunie.eldoc.ub.rug.nl/FILES/root/2004/3265200/3265200.pdf" target="_blank">http://gasunie.eldoc.ub.rug.nl/FILES/root/2004/3265200/3265200.pdf</a>><br>
<br>
"Fast pyrolyzers rapidly (?1 s) heat dry biomass (10% H2O) to ?500?C and<br>
thereby thermally transform biomass into bio-oil (?60% of mass), syngas<br>
(?20% of mass), and charcoal (?20% of mass). The energy required to<br>
operate a fast pyrolyzer is ?15% of the total energy that can be derived<br>
from the dry biomass. Modern systems are designed to use the syngas<br>
generated by the pyro- lyzer to provide all the energy needs of the<br>
pyrolyzer."<br>
from Laird, D.A. The Charcoal Vision: A Win Win Win Scenario for<br>
Simultaneously Producing Bioenergy, Permanently Sequestering Carbon,<br>
while Improving Soil and Water Quality. Agron J 100, 178-181(2008).<br>
<br>
"To improve the thermal efficiency and predict the composition of<br>
syngas, several numeric models have been developed for biomass<br>
conversion systems."<br>
from Rogel, A. & Aguill?n, J. The 2D Eulerian Approach of Entrained Flow<br>
and Temperature in a Biomass Stratified Downdraft Gasifier. American<br>
Journal of Applied Sciences 3, 2068-2075(2006).<br>
Comments: Shows a stratified downdraft model with inputs of air and<br>
biomass, outputs of syngas and ashes<br>
<br>
"The term ?pyrolysis? is typically used either for ...[analytical<br>
purposes]... or for bioenergy systems that capture the off-gases emitted<br>
during charring and used to produce hydrogen, syngas, bio-oils, heat or<br>
electricity (Bridgwater et al, 1999)."<br>
from Lehmann, J. & Joseph, S. Biochar for environmental management:<br>
science and technology. (Earthscan/James & James: 2009).<br>
<br>
"High purity syngas (i.e. low quantities of inerts such as N2) is<br>
extremely beneficial for fuels and chemicals synthesis since it<br>
substantially reduces the size and cost of downstream equipment.<br>
However, the guidelines provided in Table 5 should not be interpreted as<br>
stringent requirements. "<br>
"There is more latitude with regard to syngas composition for engine<br>
combustion than for turbine combustion."<br>
"To be considered interchangeable with conventional fossil fuels<br>
(natural gas or distillate oils) and to ensure maximum flexibility for<br>
industrial or utility applications, syngas heating value needs to be<br>
above 11 MJ/m3"<br>
"At temperatures greater than 1200-1300oC, little or no methane, higher<br>
hydrocarbons or tar is formed, and H2 and CO production is maximized<br>
without requiring a further conversion step."<br>
"Biomass gasification is the conversion of an organic...carbonaceous<br>
feedstock by partial oxidation into a gaseous product, synthesis gas or<br>
?syngas,? consisting primarily of [H2 and CO] with lesser amounts of<br>
[CO2, CH4], higher hydrocarbons (C2+), and nitrogen (N2). The reactions<br>
are carried out at elevated temperatures, 500-1400oC, and atmospheric or<br>
elevated pressures up to 33 bar (480 psia). The oxidant used can be air,<br>
pure oxygen, steam or a mixture of these gases. Air-based gasifiers<br>
typically produce a product gas containing a relatively high<br>
concentration of nitrogen with a low heating value between 4 and 6 MJ/m3<br>
(107-161 Btu/ft3). Oxygen and steam-based gasifiers produce a product<br>
gas containing a relatively high concentration of hydrogen and CO with a<br>
heating value between 10 and 20 MJ/m3 (268-537 Btu/ft3)."<br>
"Table 8. Compositions of Biomass-Derived Syngas" - includes N2 from<br>
0-56%, H2 from 5-43.3%, CO from 9-67%, CO2 from 4-40%<br>
...<br>
from Ciferno, J.P. & Marano, J.J. Benchmarking biomass gasification<br>
technologies for fuels, chemicals and hydrogen production. US Dep of<br>
Energy NETL (2002).at<br>
<<a href="http://seca.doe.gov/technologies/coalpower/gasification/pubs/pdf/BMassGasFi
nal.pdf" target="_blank">http://seca.doe.gov/technologies/coalpower/gasification/pubs/pdf/BMassGasFi<br>
nal.pdf</a>><br>
<br>
"The resulting fuel is a producer gas (a synthesis gas or syngas) that<br>
consists primarily of varying ratios of hydrogen and carbon monoxide (CO)."<br>
from Mukhtar, S. Manure to Energy: Understanding Processes, Principles<br>
and Jargon. (2006).at<br>
<<a href="http://repository.tamu.edu/bitstream/handle/1969.1/87462/pdf_2425.pdf?seque
nce=1" target="_blank">http://repository.tamu.edu/bitstream/handle/1969.1/87462/pdf_2425.pdf?seque<br>
nce=1</a>><br>
<br>
In short, the usage from the above doesn't appear entirely clear.<br>
But in general, syngas is often suggested to have been upgraded, or of a<br>
higher CO/H2/energy content. Syngas is often used to refer to gas<br>
intended to be used for synthesis of products. Syngas does also seem to<br>
be used as general term in some cases.<br>
<br>
My preferred usage has been to call the gas the air-blown GEK makes<br>
"producer gas". Wood gas notes that the carbon source was biomass,<br>
though I don't prefer the term. "Syngas" being made with O2 or steam.<br>
The problem with the above is it doesn't leave a general catch-all term.<br>
<br>
Cheers,<br>
Bear Kaufmann<br>
All Power Labs<br>
<br>
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Gasification Administrator<br>
</blockquote></div><br>