Very well explained and I am in full agreement with all the definitions. On Fri, Dec 31, 2010 at 3:24 AM, <[email protected]> wrote:
> 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 <[email protected]> > To: [email protected] > Subject: [Gasification] A small literature review re: syngas > Message-ID: <[email protected]> > 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 > > _______________________________________________ > The Gasification list has moved to > [email protected] - please update your email contacts to > reflect the change. > Please visit http://info.bioenergylists.org for more news on the list > move. > Thank you, > Gasification Administrator >
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