Identifying the key variables & architecture
The fastest way to get results is to develop a roadmap with all of the basic variables and begin troubleshooting them in order. From my reading it seems we will need:
Proper fuelgas input. This means clean gas with a 2:1 ratio of hydrogen to carbon monoxide.
Initial heat source to kickstart reactions, then exothermic release happens and necessitates...
Cooling. Temperature range is key to both hydrocarbon chain building and pulling off the various products. It seems each separate out at a different temperature range depending on their complexity.
Pressure. Some systems were atmospherically fed while others operated under pressure with better results. Feeding with oxygen would make pressure feeding easy and not need an external compressor.
Catalyst. Iron is cheap and should be the starting point. It should be noted that gas quality needs to be very high to avoid tainting the catalyst. Not sure if soot will be a problem or convert itself into CO.
Separation of byproducts. How will we separate out the waxes and other products?
Anything else?
Proper fuelgas input. This means clean gas with a 2:1 ratio of hydrogen to carbon monoxide.
Initial heat source to kickstart reactions, then exothermic release happens and necessitates...
Cooling. Temperature range is key to both hydrocarbon chain building and pulling off the various products. It seems each separate out at a different temperature range depending on their complexity.
Pressure. Some systems were atmospherically fed while others operated under pressure with better results. Feeding with oxygen would make pressure feeding easy and not need an external compressor.
Catalyst. Iron is cheap and should be the starting point. It should be noted that gas quality needs to be very high to avoid tainting the catalyst. Not sure if soot will be a problem or convert itself into CO.
Separation of byproducts. How will we separate out the waxes and other products?
Anything else?
Tags: fischer tropsch
Replies to This Discussion
-
Permalink Reply by Chris Seymour on -
Great Question! In make liquid fuels, we can look to the refining process of petrol. A wealth of information. Making a small refinery is almost technical as a big one,
I found this link, but there is more still to read out there on dewaxing and process impurity removal
Solvent Extraction and Dewaxing
Solvent treating is a widely used method of refining lubricating oils as well as a host of other refinery stocks. Since distillation (fractionation) separates petroleum products into groups only by their boiling-point ranges, impurities may remain. These include organic compounds containing sulfur, nitrogen, and oxygen; inorganic salts and dissolved metals; and soluble salts that were present in the crude feedstock. In addition, kerosene and distillates may have trace amounts of aromatics and naphthenes, and lubricating oil base-stocks may contain wax. Solvent refining processes including solvent extraction and solvent dewaxing usually remove these undesirables at intermediate refining stages or just before sending the product to storage.
http://www.setlab.com/solvent/tabid/108/Default.aspx
Thanks Chris
-
Permalink Reply by Eric Browning on -
My guess is soot might coat the catalyst with carbon (coke) and take away the activity. Sulfur is another problem. There's not usually much sulfur in wood, but typically in commercial plants sulfur is reduced to parts per billion before it reaches the reactor as it is a serious catalyst poison. I'd be curious to know about the atmospheric fed systems you mentioned. Typically in these types of reactions higher pressure is required to drive the reaction to a favorable equilibrium. Another option for catalyst would be copper if you were interested in the methanol route (and using a gasoline engine) instead of diesel.
-
Permalink Reply by ben on -
Methanol is interesting, but it definitely requires more pressure. On a home scale creating synthetic natural gas would be the simplest option as methanation is an easy reaction to produce. Natural gas is a great bridge fuel for cars and heating. Not many people heat with gasoline or diesel.
-
Permalink Reply by Eric Browning on
-
Definitely a higher pressure requirement on methanol although the others typically require relatively high pressures also from what I've seen. I like the idea of methanation since the product would require little further purification unlike methanol (distillation) and FT liquids (hydrotreating and fractionation). Also depending on the conditions you run the gasifier at you could start out with a decent amount of methane in the syngas already. The carbonyl issue is probably a larger concern with methanation though due to the nickel catalyst typically used. Definitely some periods during startup/shutdown that could produce these nasty compounds.
Welcome to
Victory Gasworks- Gasifiers and Wood Gasification
© 2010 Created by ben.
