Wet Torrefaction of Miscanthus – Characterization of Hydrochars in View of Handling, Storage and Combustion Properties

Abstract

Contribution of renewable energy sources in the world energy production is consistently increasing. This is mainly due to two reasons -depleting fossil fuels resources and climate changes. Biomass, as one of the most widely utilized renewable energy sources, has an undoubtedly meaningful impact on production of the renewable energy, not only now, but in all likelihood also in the future [IEA, 2006]. It can be used for various biofuel supply chains, for both thermoand biochemical processes, like combustion, gasification, pyrolysis, or fermentation [Kaygusuz, 2009]. Combustion is one of the simplest and best-known processes of the aforementioned. Hence, it is commonly used in power plants where biomass combustion and/or co-combustion takes place. However, introducing biomass processing into boiler operation is linked with a few problems. These involve transport and storage of

HTC of Wet Residues of the Brewing Process: Comprehensive Characterization of Produced Beer, Spent Grain and Valorized Residues

“…Clear similarity with Figure 12 in this study could be seen as grinding of hydrochars significantly increased the share of fines in the comminuted sample. Moreover, also in the case of miscanthus the differences between respective particle size distributions of samples, carbonized in different HTC conditions, were not as significant as the difference between hydrochars and raw miscanthus [39]. However, the extent of this improvement was much greater, in comparison to this study, as only slightly more than 20% of total sample mass consisted of particles smaller than 500 µm, for a cumulative share of particles of raw miscanthus after comminution [39].…”

“…Moreover, also in the case of miscanthus the differences between respective particle size distributions of samples, carbonized in different HTC conditions, were not as significant as the difference between hydrochars and raw miscanthus [39]. However, the extent of this improvement was much greater, in comparison to this study, as only slightly more than 20% of total sample mass consisted of particles smaller than 500 µm, for a cumulative share of particles of raw miscanthus after comminution [39]. A similar trend was reported for miscanthus by Kambo and Dutta [78], with some differences in particle size distribution that could be attributed to the use of different mill (ball mill) [78].…”

“…Nonetheless, the results presented in this study are in good qualitative agreement with existing literature sources. Wnukowski et al [39] presented particle size distribution of raw and wet torrefied miscanthus, after comminution in a knife mill. Clear similarity with Figure 12 in this study could be seen as grinding of hydrochars significantly increased the share of fines in the comminuted sample.…”

“…where: Y e -energy yield; HHV-respective higher heating value of feedstock and product, MJ/kg Ash yield was used, as suggested by Wnukowski et al [39] and Mościcki et al [27], as a typical indicator of the inorganic's behaviour during HTC process:…”

“…A decrease in the number of OH groups is crucial in making hydrochars hydrophobic [37] and enhancing dewatering by mechanical means [25,38]. Moreover, grindability of the processed biomass can be significantly enhanced [39]. Therefore, HTC can be considered as a prospective valorization process for low quality biomass, especially when wet biomass is concerned as a potential feedstock for biorefineries [40][41][42][43][44][45] or as a component of high quality solid biofertilizers [44,46,47].Performance of the HTC process is typically determined directly, by means of mass yield, energy yield and energy densification ratio [24,27,[41][42][43]48].…”