We’ve discussed in previous blog posts how the broad
definition of ‘gasification’ covers many diverse processes with different end
goals. These various processes can
have different benefits and costs, but the distinction is ultimately at the
chemical level. The sophisticated manipulation of the chemical process used in
the Carbo-V Technology has particularly held our interest since Linde
Engineering Dresden announced it was licensing the technology for use in a
Biomass-to-Liquid (BtL) plant last week.
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| Courtesy: Linde Engineering Dresden; Biomass Energy. |
Carbo-V Technolog is described as a multi-stage gasification
processes that was originally developed by CHOREN Industries, and acquired by
Linde in February 2012 after CHOREN went bankrupt. The subsidiary of The Linde
Group announced it was licensing the technology to Finnish Forest BtL for use
in a 480 MW plant to be built in Kemi, Northern Finland and is expected to be
operational by the end of 2016.
The Carbo-V Technology claims to have overcome the tar and
methane obstacles that frequently prohibit syngas from being used in
Fischer-Tropsch applications for the production of synthetic fuel. The
multi-stage process appears to use a sophisticated form of partial oxidation
while borrowing elements from steam reformation and re-injecting carbon into
the gas cleanup cycle.
Feedstocks suitable for the
Carbo-V Technology include rice husks, wood chips, lumber and other wood
residues. Process heat is used to dry the feedstock to 15 percent water content
before passing it through a low-temperature gasifier (400-500 degrees Celsius),
where the biomass is thermally broken down into volatile gases and solid
bio-coke or char. At the same time, a mixture of O2/CO2 and steam is injected
into the chamber.
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| A drawing of the Carbo-V Process by CHOREN. |
In the next stage, the partially
deconstructed biomass is sent through a partial-oxidation combustion chamber
that reaches 1400 degrees Celsius to continue breaking down the tar and long
chain C-H molecules. The char that has resulted from the first stage is ground
to powder and blown into the hot exit gases below the combustion chamber in a
chemical endothermal quenching process that reduces the gas temperature almost
instantaneously to approximately 900 degrees Celsius. This elimates unnecessary
temperature cycling of the char and improves Carbo-V’s cold gas efficiency.
The resulting syngas is fed
through a Fischer-Tropsch process to convert the carbon monoxide and hydrogen
into hydrocarbons. CHOREN’s white paper says that the syngas may contain small
traces of contaminants that could be harmful to sensitive Fischer-Tropsch
catalysts and says they do use scrubbers before compressing the syngas for the
Fischer-Tropsch reactor they used when producing SunFuel, before declaring
bankruptcy in 2011.
BETTER BTU TAKE: The Carbo-V Technology is a unique manipulation of
the traditional partial-oxidation process. In this tricky economic environment,
companies may falter, but a good technology will ultimately survive and it
looks like Linde Engineering Dresden is breathing new life into this technology
with its announcement of the licensing agreement with Finnish Forest BtL. Our
only concern is that a 480 MW plant will require 1.5 million tons of wood to
produce its projected 130,000 tons of biodiesel and naptha. The project is
being funded by the European Union’s NER300 for innovative, low-carbon
technologies and we’ll continue to monitor the project and bring you updates on
our project blog.
Recommended Reading:
Linde
and Forest BtL Sign Licensing Agreement for Carbo-V Techonolgy – The Linde
Group (Jan. 24, 2013)
Linde
Buys CHOREN’s Carbo-V Technology – Renewables
International, The Magazine (Feb. 15, 2012)
Sustainable SunFuel
from CHOREN’s Carbo-V Process – By Tom Blades, Matthias Rudloff and Olaf
Schulze, CHOREN Industries (Sept. 2005)project blog
