Proof-of-Concept of High-Pressure Torrefaction for Improvement of Pelletized Biomass Fuel Properties and Process Cost Reduction

Bartosz Matyjewicz,Kacper Świechowski,Andrzej Białowiec,Jacek A Koziel

doi:10.3390/en13184790

Bartosz Matyjewicz, Kacper Świechowski + Show 2 more

Open Access

https://doi.org/10.3390/en13184790

Copy DOI

Abstract

This paper provides a comprehensive description of the new approach to biomass torrefaction under high-pressure conditions. A new type of laboratory-scale high-pressure reactor was designed and built. The aim of the study was to compare the high-pressure torrefaction with conventional near atmospheric pressure torrefaction. Specifically, we investigated the torrefaction process influence on the fuel properties of wooden-pellet for two different pressure regimes up to 15 bar. All torrefaction processes were conducted at 300 °C, at 30 min of residence time. The initial analysis of the increased pressure impact on the torrefaction parameters: mass yields, energy densification ratio, energy yield, process energy consumption, the proximate analysis, high heating value, and energy needed to grind torrefied pellets was completed. The results show that high-pressure torrefaction needed up to six percent less energy, whereas energy densification in the pellet was ~12% higher compared to conventional torrefaction. The presence of pressure during torrefaction did not have an impact on the energy required for pellet grinding (p < 0.05).

Highlights

The results show that the average energy demand for processing a pellet by conventional torrefaction was 1.2 Wh·kg−1, and high-pressure torrefaction led to decreasing of this energy demand up to 1.18 and 1.13, respectively
The results show that the average energy demand for processing a pellet by conventional torrefaction was 1.2 Wh∙kg−1, and high-pressure torrefaction led to decreasing of this energy demand up to 1.18 and 1.13, respectively
The results show that the energy needed to produce 1 kg of the torrefied pellet was the lowest for hpd (Entorrefied = 2.06 Wh∙kg−1) and the highest for hps (Entorrefied = 2.13 Wh∙kg−1), respectively

Summary

Introduction

Rapid economic development resulted in a significant increase in demand for energy. The importance of renewable energy sources (RES) has been growing in recent decades. One of the most abundant RES is biomass that can be obtained from energy crops and agricultural waste. Biomass is an inexhaustible, controlled, and flexible energy source [1,2], and for these reasons, it plays an essential role in the energy supply chain in the European Union (EU) and around the world. An underestimated potential for energy production lies in residual biowaste, which cannot be recycled, and whose mass is increasing from a growing population and industrial production

Objectives

Methods

Conclusion