Wood Chip Drying through the Using of a Mobile Rotary Dryer

Abstract

Drying is a critical point for the exploitation of biomass for energy production. High moisture content negatively affects the efficiency of power generation in combustion and gasification systems. Different types of dryers are available however; it is known that rotary dryers have low cost of maintenance and consume 15% and 30% less in terms of specific energy. The study analyzed the drying process of woody residues using a new prototype of mobile rotary dryer cocurrent flow. Woodchip of poplar (Populus spp.), black locust (Robinia pseudoacacia L.), and grapevine (Vitis vinifera L.) pruning were dried in a rotary drier. The drying cycle lasted 8 h for poplar, 6 h for black locust, and 6 h for pruning of grapevine. The initial biomass had a moisture content of around 50% for the poplar and around 30% for grapevine and black locust. The study showed that some characteristics of the biomass (e.g., initial moisture content, particle size distribution, bulk density) influence the technical parameters (i.e., airflow temperature, rate, and speed) of the drying process and, hence, the energy demand. At the end of the drying process, 17% of water was removed for poplar wood chips and 31% for grapevine and black locust wood chips. To achieve this, result the three-biomass required 1.61 (poplar), 0.86 (grapevine), and 1.12 MJ kgdry solids−1 (black locust), with an efficiency of thermal drying (η) respectively of 37%, 12%, and 27%. In the future, the results obtained suggest an increase in the efficiency of the thermal insulation of the mobile dryer, and the application of the mobile dryer in a small farm, for the recovery of exhaust gases from thermal power plants.

Integrating anaerobic digestion and slow pyrolysis improves the product portfolio of a cocoa waste biorefinery

“…The energy in the gas streams (ca., 30% for monodigestion and 50% for co-digestion) always well-exceeded the upper limit of the required energy for pyrolysis, being 15%. There is even sufficient energy to additional consume 2-5 MJ • kg −1 to pre-dry the cocoa waste to a moisture content of 10 wt.% 60,61 . Depending on the market situation, the product portfolio could be skewed towards either (i) energy and high quality biochar or (ii) energy/biochar and high quality organic phase oil.…”

Indirect Dryers for Biomass Drying—Comparison of Experimental Characteristics for Drum and Rotary Configurations

“…The biomass properties such as water content, bulk density, and particle size distribution influence the operation of the dryer including the final water content of the dried material and the energy demand [13]. Satisfactory material mixing in the dryers is important for an intensive and stable drying process.…”

Framework for consequential life cycle assessment of pyrolysis biorefineries: A case study for the conversion of primary forestry residues

“…Bridgwater et al [6] recommend a water content below 10 wt% prior to feeding the pyrolyzer in order to produce a bio-oil with a water content below 30 wt%. Therefore, it is here considered that PFR are further dried to 10 wt% moisture prior to pyrolysis [14,15] with a rotary dryer [49]. The temperature generally employed is around 200°C but should not be above 250°C in order to prevent degradation of dry matter [50].…”