Oxygen-Blown Gasification of Pulp Mill Bark Residues for Synthetic Fuel Production

Fredrik Weiland,Yngve Ögren,Sandra Lundström

doi:10.3390/pr9010163

Abstract

Synthetic fuel production via gasification of residual biomass streams from the pulp and paper industry can be an opportunity for the mills to enable improved resource utilization and at the same time reduce the production of excess heat. This paper summarizes initial oxygen-blown gasification experiments with two bark residues from a European pulp and paper mill, i.e., a softwood bark and a hardwood bark. The gasification process was characterized by measuring syngas yields and process efficiency to find optimum operating conditions. In addition, impurities in the syngas and ash behavior were characterized. Maximum yields of CO and H2 were obtained from softwood bark and amounted to approximately 29 and 15 mol/kg fuel, respectively. Optimum cold gas efficiency was achieved at an oxygen stoichiometric ratio of λ = 0.40 and was approximately 76% and 70% for softwood bark and hardwood bark, respectively. Increased λ had a reducing effect on pollutants in the syngas, e.g., higher hydrocarbons, NH3, HCl, and soot. The situation for sulfur species was more complex. Evaluation of the bark ashes indicated that slag formation could start already from 800 °C. Furthermore, a non-intrusive laser diagnostics technique gave rapid feedback on the millisecond scale. Measured syngas temperature and water content were in good agreement with the applied reference methods.

Highlights

Greenhouse gas (GHG) emissions from the transportation sector represent almost a quarter of the total GHG emissions in Europe
A higher λ means that more O2 is being added to the process, resulting in higher process temperature due to increased heat generation from exothermic combustion reactions
The low process temperature for hardwood at λ ~0.40 was most likely caused by the lower starting temperature in the gasifier during that experimental day compared to the other hardwood experiments

Summary

Introduction

Greenhouse gas (GHG) emissions from the transportation sector represent almost a quarter of the total GHG emissions in Europe. Road transport was responsible for more than 70% of the GHG emissions from transport in. To reduce climate impact and accelerate development towards low-emission mobility, the European Commission adopted a strategy where alternative energy for transport was included. This strategy included the use of advanced biofuels, electricity, hydrogen, and renewable synthetic fuels for road transport [1]. Biomass production must not compete for land use with food or feed production. Biomass production should not take place in areas with high carbon stock, such as biodiverse forests, wetlands, and peatlands [2]

Methods

Results

Conclusion