358 / 2018-07-22 16:48:29

Fuel characteristics of different biomass hydrochars by HTC: Quality and combustion behaviour of hydrochar pellets

全体主题 > 生物质固体成型燃料

In China, there are a large amount of waste biomass is produced each year, if they are not used properly, not only will resources be wasted but also pollution to the environment will be caused. Therefore, hydrothermal carbonization (HTC) technology and pelletization has attracted increasing attention. In this study, the characteristics of hydrochars from HTC at different biomass raw meterials (peanut rod, peanut shells, wheat straw, cotton stalk and pine sawdust), hydrothermal temperatures (180~300°C) and reaction times (1~8 h) were investigated. The manufacture of hydrochar pellets and their pelletization energy consumption, relaxation density, compressive strength and combustion characteristics were also investigated. The results showed that peanut rod hydrochars had better energy density (1.42) and HHV (25.31 MJ/kg) than others. The content of carbon and HHV of biomass hydrochars gradually increased with the extension of the HTC temperature and reaction time. Due to dehydration and decarboxylation reactions, H/C and O/C atomic ratios of cotton stalk hydrochars reduced to 0.824 and 0.094 at 300°C-4h, respectively. There was a higher energy consumption of hydrochars during pelletization, but the pellets formed from hydrochar had higher relaxation density and compressive strength than the biomass raw material pellets. The pellet of cotton stalk hydrochar (240°C-4h) with the largest relaxation density (1.21g/cm3) and compressive strength (8.90 MPa). The integrated combustion characteristics index (Sn) of hydrochar pellets formed at lower HTC temperature were better due to the higher (dm/dt)max value. The combustion behaviour of hydrochar pellets was expected to be easier and more stable because of lower activation energy and pre-exponential factor.