Biomass properties can be improved for heat and power applications through combined torrefaction and pelleting. Good pellet quality in terms of durability, density, moisture absorption, fines production and heating value paired with a low power consumption in the pellet mill render the densification process of torrefied materials challenging. The aim of this study is to identify the lignin components/intermediates and the corresponding mechanisms during torrefaction of wood that play a role in pelleting behaviour and pellet quality. The importance of lignin lies in its ability to act as a natural binder during densification. Structural differences caused by torrefaction of spruce and poplar (270 degrees C, 32-45 min) were studied by using NMR and TD-GC/MS as well as by pressing single pellets. Spruce chips were torrefied (280 degrees C, 35-45 min) and conditioned in steam in a pilot plant. The products were ground on a 4-mm sieve and densified in a single-pellet press, where differences in the measured responses were explained on basis of their lignin properties. The lignin was isolated from the spruce samples by organosolv fractionation and characterised in terms of amount, molecular weight distribution (SEC) and glass-transition temperature (DSC). The results of the tests and analyses indicate that torrefied softwood should be densified immediately after production. Furthermore, pellet quality of the torrefied material was found to depend on the binding ability of its lignin in the presence of moisture during densification. Additionally, storage of torrefied spruce prior to densification causes reduced binding ability of its lignin leading to pellets of lower quality. (c) 2017 Elsevier Ltd. All rights reserved.

Fuel Production from Sewage Sludge using TORWASH for highly efficient dewatering and salt removal

This chapter describes the current practice with respect to transport, on-site handling, storage, milling and pneumatic conveying of biomass during co-firing in coal-fired power stations, and the associated design of handling and storage equipment, as well as the required hardware modifications to convert existing dedicated coal-fired power plants. Thermal biomass pre-treatment technologies, such as torrefaction and steam explosion, result in the production of high-quality solid bioenergy carriers that offer distinct advantages in comparison with conventional white wood pellets. The use of torrefied or steam-exploded biomass pellets mitigates extensive hardware modifications, and facilitates on-site fuel handling and storage in a manner that is more comparable with coal. The potential benefits will be described based on proprietary results with torrefied biomass pellets produced in the ECN pilot torrefaction plant. In conclusion, an overview of foreseen trends and directions for biomass processing and thermal pre-treatment for co-firing will be provided.

Biomass torrefaction was tested on pilot scale (50 kg/h throughput) for 3 types of wood: European spruce, ash and willow. Quantitative analysis of process streams was accomplished by utilising on- and off-line analytical methods. These results gave more insight into the torrefaction chemistry and formed the basis for determining mass and energy balances of the torrefaction plant. Furthermore, these data allowed a good estimation of the heat integration potential for a large-scale torrefaction process. A theoretical overall thermal efficiency of 90% was calculated for a large-scale, heat-integrated torrefaction process that uses wet woody feedstock containing 45 wt.% moisture. This demonstrates that torrefaction has good potential as a cost-effective and sustainable process for the production of solid bio-energy carriers.

TORWASH® sewage sludge treatment.Increased biogas production, highly-efficient dewatering and phosphate recovery.