Producer gas explained by Hugh McLaughlin

Hello List and John, the Concerned Citizen,

 

With respect to the vapor produced by all pyrolysis processes that are consuming biomass, it is important to pay attention to nomenclature: The heating of biomass results in
the biomass making a more carbon-rich solid and emitting a vapor stream called “Producer Gas” or Wood Vapor or Wood Gas – it has many small organic compounds and lots of water vapor and lesser amounts of carbon dioxide and CO, H2. etc.

 

Notably, Producer Gas is not Synthesis Gas (aka Syn Gas). Syn Gas is what happens when wood gas is heated to much higher temperatures, sometimes in the presence of a catalyst,
and converts most of the organics to either carbon monoxide, hydrogen or methane, which are the stable forms of organics at high temperatures. The Syn Gas can be treated, typically to remove the excess water vapor and carbon dioxide, and subsequently converted
to many things, including gasoline and diesel.

 

The big issue for Producer Gas is the water vapor, which is usually very close to saturation and results in fog and smoke formation when the Producer Gas is cooled and/or compressed.
The water condenses and absorbs many of the small soluble organics, especially acetic acid, resulting in a liquid called “Wood Vinegar”, with a pH low enough to cause corrosion in common steel and even attacks lower grades of stainless.

 

Unfortunately, modern science and engineering do not have a good way to get the water vapor away from the rest of the vapor stream or split the condensate into parts of value
and lots of clean water. Generally, the wood vapor is kept hot and combusted with an excess of air to yield heat in a hot vapor stream with a lot of water vapor, carbon dioxide and nitrogen (from the combustion air). The exiting vapor, prior to any treatment
to convert it to syn gas, generally has an energy density between 100 and 250 Btu/ft3, or one quarter to one tenth of natural gas.

 

It is a difficult challenge because one cannot compress or cool the stream into a stream that can be transported in a form that has sufficient energy density, which is the
amount of energy per unit volume. However, it is a challenge that needs to be met, since a gigaton of biochar will be accompanied by a gigaton of Producer Gas, which needs to go somewhere and do something.

 

– Hugh

On Monday, May 20, 2024 at 05:02:51 PM EDT, Concerned Citizen <elritojohn@gmail.com> wrote:

 

 

Hi

 

Good work getting LANL involved. 

 

My interest is in the fuel value of the syngas produced, and the possibilities for using it as a replacement for propane and natural gas.  So BTU/ft3, tar content,
precipitants, pH etc,  would be very helpful 

 

Thanks 

John

 

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