Abstract
Mitigation of climate change by stabilizing the global mean temperature
rise well below 2°C from the pre-industrial temperature level requires implementation of negative emission technologies (NETs). One of the most promising NETs is chemical looping combustion of biomass (bio-CLC). Biomass has the capability of withdrawing and storing atmospheric CO2 during growing. CO2 released from biomass during combustion can be captured and stored permanently underground, thus resulting net-negative CO2 emissions to the atmosphere. Recently bio-CLC has been tested in pilot and laboratory scale. Results with different solid biomass types and oxygen carriers has been published. The most important and common operational challenge has been deficient mixing and contact between oxygen transported by oxygen carriers
and volatiles released from biomass. This leads to insufficient combustion of gaseous species and high oxygen consumption in subsequent oxygen polishing unit. Also high concentrations of tars has been observed increasing the risk of operational problems. In this paper, pilot scale experimental results of bio-CLC with results of computational fluid dynamics (CFD) simulations of mixing are presented. Experimental tests were carried out with wood based pellets and wood char using ilmenite (iron based) and braunite (manganese based) as oxygen carriers. CFD simulations were used to study volatile gas by-pass differences observed in the experiment. The fluidized oxygen carrier bed was simulated using two-phase Euler-Euler approach. Fuel particles were
included in the simulation as Lagrangian particles with models for evaporation,
pyrolysis and gasification. CFD simulations were carried out with different fuels and particle size distributions. Simulation results are used to study the distribution of volatile release from different fuel particles and contact between the oxygen carriers and volatiles. Based on the results, an alternative reactor configuration that could decrease volatile gas bypass is simulated to illustrate how CFD simulations can be beneficial in design of pilot and large scale CLC systems, especially in fuel reactor and fuel feeding design.
rise well below 2°C from the pre-industrial temperature level requires implementation of negative emission technologies (NETs). One of the most promising NETs is chemical looping combustion of biomass (bio-CLC). Biomass has the capability of withdrawing and storing atmospheric CO2 during growing. CO2 released from biomass during combustion can be captured and stored permanently underground, thus resulting net-negative CO2 emissions to the atmosphere. Recently bio-CLC has been tested in pilot and laboratory scale. Results with different solid biomass types and oxygen carriers has been published. The most important and common operational challenge has been deficient mixing and contact between oxygen transported by oxygen carriers
and volatiles released from biomass. This leads to insufficient combustion of gaseous species and high oxygen consumption in subsequent oxygen polishing unit. Also high concentrations of tars has been observed increasing the risk of operational problems. In this paper, pilot scale experimental results of bio-CLC with results of computational fluid dynamics (CFD) simulations of mixing are presented. Experimental tests were carried out with wood based pellets and wood char using ilmenite (iron based) and braunite (manganese based) as oxygen carriers. CFD simulations were used to study volatile gas by-pass differences observed in the experiment. The fluidized oxygen carrier bed was simulated using two-phase Euler-Euler approach. Fuel particles were
included in the simulation as Lagrangian particles with models for evaporation,
pyrolysis and gasification. CFD simulations were carried out with different fuels and particle size distributions. Simulation results are used to study the distribution of volatile release from different fuel particles and contact between the oxygen carriers and volatiles. Based on the results, an alternative reactor configuration that could decrease volatile gas bypass is simulated to illustrate how CFD simulations can be beneficial in design of pilot and large scale CLC systems, especially in fuel reactor and fuel feeding design.
| Original language | English |
|---|---|
| Title of host publication | 5th International Conference on Chemical Looping |
| Number of pages | 19 |
| Publication status | Published - 2018 |
| MoE publication type | D3 Professional conference proceedings |
| Event | 5th International Conference on Chemical Looping - Utah, United States Duration: 24 Sept 2018 → 27 Sept 2018 |
Conference
| Conference | 5th International Conference on Chemical Looping |
|---|---|
| Country/Territory | United States |
| City | Utah |
| Period | 24/09/18 → 27/09/18 |
