Experimental evaluation of a 35 kVA downdraft gasifier

Abstract

Energy conversion systems based on biomass are particularly interesting because biomass utilization effectively closes the carbon cycle besides achieving self-sustainability. Biomass is particularly useful for highly populated and agriculture dependent economic nations like China and India. A compact and cost effective downdraft gasification system was developed. The present paper describes an experimental investigation on a biomass based gasifier engine system with a capacity of 35 kVA for power generation application. The problem of cooling and cleaning the hot and dirty gas from the gasifier has been satisfactorily solved by the effective cooling and filtration system. The gasifier developed is observed to be operation friendly. The quality of gas was evaluated in terms of its composition, conversion efficiency and total particulate matter. The maximum output of the power plant was obtained at the combustion zone temperature of 850ºC. The experimental investigations showed that the percentage reduction in total particulate matter is 89.32%. The conversion efficiency of the biomass gasifier is found to be dependent on the operation conditions and fuel properties of the gasifier. The optimum value of equivalence ratio was observed to be 0.3134 for achieving the maximum gas conversion efficiency of the present gasifier configuration.

Key words： biomass; gasification; producer gas; equivalence ratio; total particulate matter; conversion efficiency of gasifier

Acknowledgements

This work was financially supported by MIT, Aurangabad, Maharashtra, India. Thanks also go to Enviro Tech, Aurangabad, Maharashtra, India for their cooperation.

Notations

CH4vol	Volume concentration of methane/%
{\mathrm{CO}}_{H_2}	The gas heating value for hydrogen/(MJ·Nm-3)
COCO	The calorific of carbon monoxide/(MJ·Nm-3)
{\mathrm{CO}}_{{\mathrm{CH}}_2}	The calorific of methane/(MJ·Nm-3)
COvol	The volume concentration of carbon monoxide/%
Czt	Combustion zone temperature/ºC
ER	Equivalence ratio
f	Frequency/Hz
Hg	The gas calorific value/heating value/(MJ·Nm-3)
H2vol	The volume concentration of hydrogen/%
Hw	Average value of wood/(MJ·kg-1)
IL	Line current/A
Iavg	Average current/A
Pg	Power generated/kVA
Q	Gas flow rate/(Nm3·kg-1)
RL	Resistive load/kVA
RPM	Revolution per minute
Vp	Phase voltage/V

Greek letter

η	Gas conversion efficiency/%

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