Kinetikexperiment på Ilmenit, LD-slagg och järnsand som syrebärare.
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Typ
Examensarbete för masterexamen
Program
Publicerad
2020
Författare
Brantebäck, Daniel
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
In Paris 2015 the decision was made that the global temperature would not exceed a 2°C
increase since the industrial revolution. To reach this goal more environmentally friendly
methods have to be developed. One such method is Carbon Capture Storage(CCS), this
method captures carbon dioxide before or after the combustion stage to then store it
underground. The big challenge is to find an economical and energy sustainable method to
extract the carbon dioxide from air. Chemical looping Combustion(CLC) is one such method
that is being researched. The CLC method splits the reaction in two parts, an air reactor and
a fuel reactor. Where in the air reactor the bed material oxidizes and is transported to the
fuel reactor where the bed material is reduced. With this method air and fuel never mix,
which results in a flue gas without nitrogen. As this flue gas is not diluted with nitrogen the
gas can be used for CCS. There are similar methods to CLC, Chemical Looping
Reforming(CLR) and Chemical Looping Gasification(CLG), where the flue gas instead of
carbon dioxide contains carbon monoxide and hydrogen also known as Syngas. Syngas can
be used for fuel or chemical production.
In this report the kinetics of three iron-based oxygen carriers; Ilmenite, LD-slag and Järnsand
were tested in the mass conversion interval of 1>ω>0.98. In these experiments the method;
pulsing was used, which means that the fuel gas was introduced in short time periods, this
was used mainly to avoid back-maxing in the analyser. The oxygen carriers were tested at
different temperatures and ω to determine how these two factors influenced the reaction.
The experiments showed that ω did not have any effect on the conversion rate for Ilmenite,
but for LD-slag and Järnsand the conversion rate drastically dropped when they were not
fully oxidized. Järnsand gave multiple indications of reforming methane to carbon monoxide
and hydrogen to a higher degree instead of conversion to carbon dioxide and water, but still
had a lower conversion rate of methane than both LD-slag and Ilmenite. Ilmenite was the
most promising oxygen carrier for both CLC and CLR/CLG as it had the highest conversion
rate to both carbon dioxide and carbon monoxide. The formation of carbon monoxide for
Ilmenite and LD-slag was less than the carbon dioxide formation for every experiment,
therefore these should be tested in an environment with lower oxygen concentration to get a
deeper understanding of its application in CLR/CLG.