engleski

Upgrading of a fuel potential of waste biomass via hydrothermal carbonization

In recent decades, the massive exploitation of fossil fuels, with a detrimental impact on the environment, caused a growing demand for the production of energies from renewable sources. One of the researchers' solutions was the application of waste biomass, but there are many disadvantages of its direct utilization, that include high moisture content, low energy content, high volatiles content, etc. In order to overcome these disadvantages, attention has been focused toward development of technologies for conversion of biomass into a multi-functional products. Hydrothermal carbonization (HTC) has recognized as highly effective technology for production of carbon rich material, hydrochar, from wet and waste biomass. Hydrochar possess a great potential for application as an energy source, for environmental protection, in agriculture. In this paper, three selected biomasses (corn cob (CC), Paulownia leafs (PL) and olive pomace (OP)) were hydrothermally carbonized at different temperatures (180, 220 and 260°C). The main goal of this study was to examine the influence of temperature on the structure and fuel characteristics of the obtained products and to compare it with the precursor. The results showed that the solid yiels decreases significantly with increasing temperature in all samples. On the other hand, C content increase upon temperature increment and reach the highest values in hydrochars obtained at 260°C (69.30% for CC, 64.54% for PL and 70.97% for OP). Also, a decrease in O/C and H/C atomic ratios with increasing temperature was observed. The results are shown in the Van Krevelen diagram, which reveals the transformation of precursors during carbonization from the biomass to the lignite region. Furthermore, with decrease of O/C and H/C ratio, higher heating value (HHV) was increasing and reaches the maximum values for hydrochars prepared at 260°C (27.33 MJ/kg for CC, 28.06 MJ/kg for PL and 30.55 MJ/kg for OP). The same trend is noticeable with ED contents. Also, the content of volatile matter (VM) was determined in all samples. VM decreases (from 90.45 to 55.42% for CC, from 76.70 to 62.10% for PL, from 82.86 to 66.77% for OP) with temperature contributes to less evaporation and pollutant emission during direct combustion. According to results, can be concluded that temperature has a great influence on the structure and characteristics of the obtained products, that dehydration and decarboxylation during HTC provoke intensive biomass carbonization and that hydrochars obtained at higher temperatures have significantly enhanced fuel properties and less volatiles compared to the biomass.

Hydrothermal carbonization ; Hydrochar ; Waste biomass ; Biofuel

nije evidentirano