Hydrogen rich syngas production from food waste via an integrated two-stage process of in-situ steam gasification after fast pyrolysis

ABSTRACT

This study introduced an integrated two-stage process (ITP) for treating the mixed food waste (MFW) and producing syngas with higher hydrogen fraction where in-situ steam gasification was conducted after fast pyrolysis at the same temperature. Characteristics of syngas (syngas yield, composition, H₂ yield, and high heating value (HHV)) from the proposed approach was first compared with that from conventional overlapping process (COP) of steam gasification process at the same temperature of 700°C and then with that from ITP at a higher temperature of 850°C. Syngas yield from ITP at 700°C (0.91 m³/kg) was almost the same as the syngas yield from COP at 700°C (0.85 m³/kg); however, the hydrogen and CO fraction were much higher (H₂: gasification part~ 63%, average ~ 57.8%; CO: gasification part ~ 25%, average ~ 24%) than that from COP at 700°C (H₂: 52%, CO: 19%). The hydrogen fraction in syngas further increased to 68% (from the gasification part) on increasing the ITP temperature to 850. Moreover, the syngas yield increased significantly (1.51 m³/kg) at the higher temperature of 850°. Finally, change in HHV values and corresponding changes in cold gas efficiency (CGE) were also presented to evaluate the process performance.

KEYWORDS:

• Fast pyrolysis
• in-situ steam gasification
• syngas
• hydrogen
• HHV

List of abbrevations

ITP Integrated two-stage process

MFW Mixed food waste

HHV High heating value

COP Conventional overlapping process

CGE Cold gas efficiency

ASTM American society

AOAC Association of official analytical collaboration

LPM Litres per minute

GC Gas chromatography

WGR Water gas reaction

WGSR Water gas shift reaction

Disclosure statement

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