Experimental studies on Chemical-looping combustion in a packed-fluidized bed: Effects of packing type and bed height
Typ
Examensarbete för masterexamen
Program
Sustainable energy systems (MPSES), MSc
Publicerad
2021
Författare
Tsuji, Yukari
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Chemical Looping Combustion (CLC) is a technology that can be used as a gas
separation technology for Carbon Capture and Storage (CCS). Compared to other
alternatives, it is considered to have lower investment and operational costs per
amount of CO2 captured. CLC utilizes fuel and air reactors where the use of fluidized
beds can be an advantage. For industrial applications, fuel conversion rates for
higher bed heights need to be improved. One possible solution could be to add
packings in the reactors to inhibit bubble growth and possibly increase the fuel
conversion rate by increasing the mass transfer rate.
This project investigated possible improvements of fuel conversion rate in a packed
fluidized bed for Chemical Looping Combustion(CLC). Two types of fuel, Syngas
and CO, were tested with two different types of packings, RMSR and Hiflow® ring,
as well as without packings. All tests were conducted with a small laboratory scale
reactor and bed heights between 10 and 60 cm.
The results show that the fuel and CO conversion rates increase as the bed height
increases. This could be due to spouting or insufficient fluidization when having
a lower bed height, leading to a shorter reaction path. The relative increases in
conversion rate are the highest for lower bed heights. However, for taller beds
the conversion rates are above 96 % without packings and approach 100 % with. A
fluidized bed equipped with RMSR has the best overall fuel conversion rates but use
of packings in general showed an improvement when compared to the experiments
without them. For higher beds without packings there were some observations
indicating large bubble formation. The lack of similar observations when packings
were used could indicate that the they are inhibiting the formation of large bubbles
as intended. In conclusion, the use of packings in a fluidized bed for CLC seems
to increase the the fuel conversion rate, possibly through the inhibition of bubble
growth.
Further studies, with taller beds as well as with other packings with different geometries
and materials, under different operating temperatures and pressures, are
recommended. Study of bubble formation and inhibition with packings in a fluidized
bed can also contribute to the understanding of the effect of packings for bubble
inhibition and hence the rates of mass transfer and fuel conversion.
Beskrivning
Ämne/nyckelord
Packed-fluidized bed , Chemical-looping combustion , CCS , metal random packing , fuel conversion