Supplementary information files for Hydrothermal carbonisation of mixed agri-food waste: process optimisation and mechanistic evaluation of hydrochar inorganic chemistry

© the authors, CC-BY NC ND 4.0Supplementary information files for Hydrothermal carbonisation of mixed agri-food waste: process optimisation and mechanistic evaluation of hydrochar inorganic chemistryIn this study, low-quality mixed agri-food waste (MAFW) was upgraded into homogenous high-quality solid fuel (i.e., hydrochar) via hydrothermal carbonisation (HTC). Response surface methodology (RSM) and principal component analysis (PCA) were used to study the effect of temperature (190–230 °C), residence time (1–5 h) and solid loading (5–20 %) on hydrochar fuel characteristics and provide mechanistic insights into hydrochar inorganic chemistry. In addition, HTC operating conditions were optimised to maximise hydrochar yield and calorific value and minimise ash content. Results from RSM revealed that reaction temperature and solid loading had most influence on the studied responses. The process optimisation of the HTC of MAFW resulted in hydrochar yield, calorific value and ash content of 52.25 %, 24.56 MJ/kg and 6.20 % (further validated within 3 % error), respectively at optimum operating condition of ⁓212 °C, 5 h and ⁓7.8 % solid loading. Furthermore, analysis by PCA revealed solid loading had a more significant impact on the fate of inorganic elements compared to reaction temperature and residence time. The results also suggests that inorganics are less concentrated in hydrochar at low solid loading and medium reaction severity. Compared to the raw-MAFW, the likelihood of fouling and slagging during combustion was reduced in the hydrochar.

© 作者版权，CC-BY NC ND 4.0附加信息文件：混合农业食品废物水热碳化研究：水热碳化过程中水炭的无机化学机理评价与工艺优化
在本研究中，通过水热碳化（HTC）技术，将低品质混合农业食品废物（MAFW）升级为均质高品质固体燃料（即水炭）。本研究采用响应面法（RSM）和主成分分析（PCA）来研究温度（190–230 °C）、停留时间（1–5 h）和固体负荷（5–20 %）对水炭燃料特性的影响，并提供了对水炭无机化学机理的深入见解。此外，对HTC操作条件进行了优化，以最大化水炭产量和热值，并最小化灰分含量。响应面法的结果显示，反应温度和固体负荷对研究响应的影响最为显著。混合农业食品废物水热碳化的工艺优化导致在最佳操作条件⁓212 °C、5 h和⁓7.8 %固体负荷下，水炭产量、热值和灰分含量分别为52.25 %、24.56 MJ/kg和6.20 %（误差进一步验证在3 %以内）。此外，主成分分析表明，固体负荷对无机元素命运的影响比反应温度和停留时间更为显著。研究结果还表明，在低固体负荷和中等反应严重程度下，无机物在水炭中的浓度较低。与原始混合农业食品废物相比，水炭在燃烧过程中产生积灰和结渣的可能性降低。