Rice husk fixed bed gasification for circular economy in compact rice mills

ABSTRACT

Considering the physicochemical properties of residual rice husk, which is suitable for gasification and its vast availability in Colombia, an experimental analysis of the energy potential of rice husk for small-scale fixed bed gasification processes was conducted, thereby facilitating the implementation of the circular economy model in compact rice mills. Because of the impact of air flow on the process equivalence ratio (ER), gas calorific value, and gasifier thermal power, the optimum air superficial velocity (VS_air) considering the end use of the producer gas for both internal combustion engines (ICEs) and atmospheric burners (AB), is examined. According to the results, biomass consumption rate, cold gas efficiency (CGE), and process temperature increased in the ranges 1–1.55 kg/h and 45–65% and 825–950°C, respectively, when ER goes from 0.23 to 0.3. To obtain the highest process performance, the process should be conducted at a VS_air ~ 5.1 m/min and ER ~ 0.3. Under these parameters, a gas with thermal power and lower heating value (LHV) of 3.6 kWth and 4.78 MJ/Nm³, respectively, was obtained. These properties allow for an engine fuel quality (EFQ) of 1817 kJ/kg. For comparison, an ICE designed to be fueled with natural gas (EFQ of natural gas approx. 2650 kJ/kg) would have a ~ 30% drop in its maximum power when fed with the producer gas obtained through rice husk gasification.

Graphical Abstract

KEYWORDS:

• Biomass gasification
• bioenergy
• circular economy
• downdraft reactor
• internal combustion engines
• atmospheric burners

Highlights

• The analyses of the rice husk gasification and the uses of its gas in ICEs and burners are addressed.

• Performance parameters for rice husk gasification in an inverted-downdraft reactor are established.

• The optimal process condition for the use of gas in engines matches that for burners if the maximum for power and gas LHV is reached under the same operating condition.

• Mathematical relationships for designing a burner that allows the use of producer gas at atmospheric pressures are presented.

Acknowledgments

Authors wish to thank to the I. U. Pascual Bravo which supported the present research with its programs “Convocatorias Tecnología e Innovación” and “Pascualino Creativo e Innovador.”

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Yuhan Arley Lenis Rodas

Yuhan Arley Lenis Rodas, MSc in engineering and PhD in mechanical engineering. Full-time Professor in the Department of Mechanical from the Institución Universitaria Pascual Bravo. His research work is focused on biomass gasification and internal combustion engines.

Andrés David Morales Rojas

Andrés David Morales Rojas, MSc in mechanical engineering. Full-time Professor in the Department of Mechanical from the Institución Universitaria Pascual Bravo. His research work is focused on advanced combustion in ICE’s.

Salomón Jaramillo Marín

Salomón Jaramillo Marín is an Mechanical engineer from the Institución Universitaria Pascual Bravo, Assistant researcher scientist.

Camilo Salcedo Jiménez

Camilo Salcedo Jiménez is an Mechanical engineer from the Institución Universitaria Pascual Bravo, Assistant researcher scientist.

Juan Fernando Pérez Bayer

Juan Fernando Pérez Bayer, PhD in energy engineering. Full-time Associate Professor in the Department of Mechanical Engineering from the University of Antioquia - UdeA.

Mechanical engineer from the Institución Universitaria Pascual Bravo, assistant researcher scientist.