Effect of experimental conditions on biomass gasification in an entrained-flow reactor

1. Effect of experimental conditions on biomass gasification in an entrained-flow reactor Ke Qin Supervisors: Prof. Anker Degn Jensen Assoc. Prof. Peter Arendt Jensen Assoc. Prof. Weigang Lin

2. Outline • Introduction • Experimental • Apparatus • Biomass fuels and applied operating condition • Results and discussion • Effect of temperature • Effect of excess air coefficient • Effect of steam/carbon molar ratio • Effect of biomass type • Conclusions

3. Introduction> Experimental> Results and discussion> Conclusions Background • Gasification is one of the key technologies for biomass utilization, especially in the field of liquid fuels and chemicals production. • In production of liquid fuels, it is important to control the syngas quality from gasification with respect to both the H2/CO ratio and harmful impurities, such as tar. • Of several gasification methods, the entrained flow gasifier has the advantage to produce a gas with low tar content and possibility to run at high temperature and pressure.

4. Introduction> Experimental> Results and discussion> Conclusions Objective • In this work, biomass gasification was investigated in atmospheric • pressure entrained flow reactor with respect to • gas composition • soot • tar • as a function of operating conditions, such as • temperature (T) • excess air coefficient (λ) • steam/carbon molar ratio (H2O/C) • biomass type

5. Introduction> Experimental> Results and discussion> Conclusions Setup - Entrained flow reactor Fuel feeder Feeding gas (air) Main gas (air+steam) Vent Flue gas treatment Flue gas cooler Gas sampler and analyzer Solid sampler Liquid sampler

6. Introduction> Experimental> Results and discussion> Conclusions Fuels Proximate and ultimate analysis (on a delivered basis) High alkali content

7. Introduction> Experimental> Results and discussion> Conclusions Gasification processes and reactions Reactor Reactor outlet compounds Pyrolysis Inlet to reactor - Unconverted char - Soot - Tar - Hydrocarbons - Main gas species H2,CO, CO2 , and N2 - Trace species COS, H2S,NH3 and so on Partial combustion Biomass Char and soot gasification O2+N2 Water gas shift reaction Steam Soot formation

8. Introduction> Experimental> Results and discussion> Conclusions Effect of temperature on soot and tar • High temperature favors soot formation, but at higher temperature soot also has a higher gasification reactivity. • There is a trade off between tar and soot formation because of soot formation from tar and hydrocarbons polymerization.

9. Introduction> Experimental> Results and discussion> Conclusions Effect of temperature on producer gas Producer gas = H2, CO, CO2 and CxHy • The yield of producer gas increases as the temperature increases. Gas formation is caused by the conversion of tar and larger hydrocarbons into lighter gaseous products.

10. Introduction> Experimental> Results and discussion> Conclusions Effect of temperature on gas composition • The yields of H2 and CO increase and CO2 decreases with increasing temperature. • The yield of CxHy decreases because it is converted to soot and light gases at higher temperature.

11. Introduction> Experimental> Results and discussion> Conclusions Conclusions • Gasification of wood and straw has been investigated in a • laboratory scale atmospheric pressure entrained flow reactor. • The residence time of fuel in the entrained flow reactor was 1-2s. Char was completely converted. • The amount of producer gas (H2, CO, CO2 and CxHy) increases significantly when the temperature increases from 1000ºC to 1350ºC, which is caused by the conversion of tar and larger hydrocarbons into lighter gaseous products. • There is a trade off between tar and soot formation. At 1350ºC, tar is minimized, but soot is present in the gas (35.26g/kg fuel). • The soot yield can only be slightly reduced by addition of steam. • Wood and straw gasification provides similar gas composition. Straw has a high alkali content, but itdoes not change the gas composition significantly.

12. Thanks for the Attention !