Talk:Gasification
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What is the air / steam flow co- and counter-current with, the motion of the fuel? If the fuel moves, why is it called "fixed-bed"? Thanks.
--- The final resting area of char, that is currently undergoing the gasification processes, resides at a fixed bed depth (downdraft) N/cm from the original (raw unburnt feedstock (before heat and air where applied)), this final resting area is where the said char is completely reformed to (A)gas (producer, or syn gas) and (B)mineral ash (ash). At this point, the spent ash simply falls through the final bed retainment, and is replaced by more char that will undergo the same reforming process. The consumption or reforming process retains this level N/cm from the raw fuel area, by means of mecanical or gravity retention. Therefore the fuel is constantly moving to the said fixed bed.
Side note: some "slipped char" also moves past the final bed area and is known as "spent char".
A31ford 12:12, 30 April 2006 (UTC)
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The optimal flow of the gasification agent (air/oxygen/steam) in a fixed bed gasifier depends on the reactivity of the fuel (how fast it reacts chemically with the gasification agent at the given temperature) and by the energy effect you need from the gasifier. A faster flow results in a faster conversion, but also in a thinner gas, eventually approaching the exhaust from pure combustion. The gas flow is much faster (several m/s) than the movement of the char (several cm/hour).
The fuel particles in the "fixed bed" is nearly fixed in space. It is a correct observation that it does move as the fuel is consumed. But as indicated above, this movement is very slow.
My visits to the UK left me wondering why there are so many abandoned gas works there. Why were they built (what was the advantage over using the fuels involved to generate electricity), why are so many of them still around, and what did they usually run on? The article explains how the process works very well, but since gasworks redirects here, it'd be nice to elaborate on the actual gas works themselves. Bz2
The reason that there would be old gas plants is that when natural gas was discovered in UK waters, old fashioned 'town gas' (from coal as I understand it) became uneconomical and so the gas works closed. Having said that, I haven't noticed many abandoned gasworks but then I live in Scotland so I can't vouch for the whole of the UK. Neither am I confident that I would know what a gasworks looked like!Ewan carmichael 13:06, 15 October 2007 (UTC)
- I think you will also find that the old gas works were pretty horrendously polluting. There were town gas facilities for municipal production but also dedicated facilities for factories. Many of the old gas works sites are highly polluted. In Stockport for instance the old gas works was demolished a number of years ago and a carpark built over the top with a shopping centre to seal in the pollutants. I think you will find most of them have suffered the same fate. Natural gas is much cleaner, safer and economical. You used to be able to commit suicide by poisoning yourself putting your head in the oven and turning the gas on.--Alex 13:27, 15 October 2007 (UTC)
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- Town gas had many environmental problems, but the reason you could commit suicide by inhaling it was due to its content of carbon monoxide, which is otherwise not really an environmental concern. The town gas process produced loads of problematic carcinogenic tar (mainly PAHs), which can indeed kill you, but it generally takes decades die from cancer. Just to explain that the instant lethality of town gas is not directly related to it being less clean.
--Claus Hindsgaul 07:22, 16 October 2007 (UTC)
[edit] We need the equation for this process written in the article
A chemical reaction equation for this process needs to be presented in the article so that people know exactly what the inputs are, what the intermediate reactions are, and what the outputs of the process are. Could someone do that? AppleJuggler 04:47, 6 June 2007 (UTC)
Not really. The reason being every feedstock is different, especially considering the inclusions that go along with the process. For example, lower ranked coal is going to have a different reaction than, say, traditional west virginia bituminous coal. polymers are going to have an alotgether different reaction than heavy oil. Xilften 18:21, 10 August 2007 (UTC)
Yes, but the basic reactions are always the same; see biomass gasification. I'm going to add them here. --Jonathan Stray 10:03, 13 August 2007 (UTC)
[edit] Regasification
We need a section in the article about regasification. (Could have a new article, but either article would not be very large.) WikiDon (talk) 00:55, 21 May 2008 (UTC)
As far as I can google, regasification is just the process of evaporating liquefied natural gas before unloading from a transport unit to a gas pipeline. It has no connection to the gasification process. Regasification is already explained at the Liquefied natural gas page. You may put up a new page to explain the process in detail, but I dont think that even a pointer from the top of the gasification page would be in place. --Claus Hindsgaul (talk) 05:23, 21 May 2008 (UTC)
