Investigating the potential for a self-sustaining slow pyrolysis system under varying operating conditions

Abstract

This work aimed to investigate the impact of highest treatment temperature (HTT), heating rate, carrier gas flow rate and feedstock on the composition and energy content of pyrolysis gas to assess whether a self-sustained system could be achieved through the combustion of the gas fraction alone, leaving other co-products available for alternative high-value uses. Calculations based on gas composition showed that the pyrolysis process could be sustained by the energy contained within the pyrolysis gases alone. The lower energy limit (6% biomass higher heating value (HHV)) was surpassed by pyrolysis at ⩾450°C while only a HTT of 650°C consistently met the upper energy limit (15% biomass HHV). These findings fill an important gap in literature related to the energy balance of the pyrolysis systems for biochar production, and show that, at least from an energy balance perspective; self-sustained slow pyrolysis for co-production of biochar and liquid products is feasible.

Strategies for producing biochars with minimum PAH contamination

“…The opposite was, observed by Zhou et al (2014b) [43]. As the lignin content of straw pellets and wood pellets used in the current study was very similar (~22%, analysed in Crombie and Mašek (2014) [44]), the content of lignin cannot explain the trends observed in our study. Besides lignin content, the composition of lignin, which is very different between straw and woody biomass [45,46] could be at least partly responsible for differences in PAH content, however, …”

Development of a gained stability index for describing biochar stability: Relation of high recalcitrance index (R50) with accelerated ageing tests

“…It is further proposed the graphite reference be replaced by a pyrolysed cellulose (PCELL) reference, as it is one of the main components of lignocellulosic biomass. Some studies have performed an evaluation of biochar production in a self-sustainable manner from laboratory to pilot scale [13,14,27], where the highest HHT was found to be 750 • C and typical residence times ≤ 20 min. Limiting commonly biochar production in a range between 350 to 750 • C temperatures, pure cellulose was pyrolysed at 750 • C. The R50 value was 0.62 that is the new unit of the scale.…”

Assessment of sustainable biochar production for carbon abatement from vineyard residues

“…Crombie and Mašek [25] based on a literature review, adopted a range of energy of 6-15% biomass HHV required for pyrolysis. In the present work, the energy required by the PPR was determined as 2.79 MJ/kg feedstock or 16.9% of feedstock HHV which is higher than the previous statement.…”

“…These conditions are listed in the European Biochar Certification-Guidelines for a Sustainable Production of Biochar (EBC) [21] including: that it must be ensured that all non-organic waste such as plastic, rubber, electronic scrap has been removed; must be free of paint, solvents and other organic or non-organic contaminants; when using primary agricultural products, it must be guaranteed that these were grown in a sustainable manner; feedstock used for the production of biochar must not be transported over distances greater than 80 km with an exception made for pyrolysis additives or special biomasses for use in production tests and the International Biochar Initiative (IBI) [22] suggests some information about the feedstock to report, such as: material composition (feedstock ingredients); specify whether the material was processed or not (virgin). The use of the co-products from biochar production to supply energy to the pyrolysis process seems to be promising, there are several studies on energy requirements for pyrolysis of different feedstock [23,24], and the evaluation of self-sustainable processes in bench scale [25].…”