Demonstration scale of a rotary kiln for cement production using a thermal plasma: A scaling and heat transfer study
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Sustainable energy systems (MPSES), MSc
Publicerad
2023
Författare
Fakt, Alice
Nilsson, Minea
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The cement industry plays a significant role in global greenhouse gas emissions,
prompting governments worldwide to establish targets for mitigating the impacts
of global warming and the greenhouse effect. This master thesis therefore focuses
on reducing the greenhouse gas emissions from the cement process, in collaboration
with Swedish cement manufacturer Heidelberg Materials Sweden. The proposed approach
involves replacing the conventional fossil fuel flame in the rotary kiln with
an electrical thermal plasma. However, direct implementation to full scale processes
are seldom done due to feasibility uncertainties and large costs, consequently, this
thesis is done on a demonstration scale of a rotary kiln. The study was conducted
with modelling tool simulations, using a model previously developed in Matlab at
the division of Energy Technology at Chalmers University of Technology.
The aim of the thesis is to investigate the heat transfer in a demonstration scale
rotary kiln operated with a thermal plasma, with carbon dioxide utilised as both
the working gas in the plasma and the secondary gas. Moreover, the design and
operational parameters that a rotary kiln would have in order to fulfil the temperature
requirements for cement production are also examined. The expected outcome
is a proposed design of a demonstration scale kiln, used for Heidelberg Materials
Sweden’s process.
The results from the simulations imply that it is viable to design a demonstration
scale rotary kiln operated with a thermal plasma. It is concluded that the heat
transfer is equally as good as for the fossil fuel driven kiln, and the temperature
requirements are achieved. Two different designs are found to be good options, one
where the plasma is tilted towards the bed material, then the bed material reaches
the desired temperature, whereas the flue gas is still high. The other design is to
tilt the plasma towards the bed as well as increase the mass flow of bed material,
and add particle content to the plasma as to increase radiation. Then the bed
material achieves the desired temperature, as well as a lower flue gas temperature
similar to the existing rotary kiln at Heidelberg Materials. To further investigate the
impact of a thermal plasma in rotary kilns, experimental research is encouraged, for
example to examine the temperature profile of larger plasmas and how the actual
heat transfer affected is when implementing it in a rotary kiln.
Beskrivning
Ämne/nyckelord
cement production , rotary kiln , thermal plasma , heat transfer mechanisms , Matlab model