Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo, Hokkaido, Japan.
Agricultural and Bioresources Engineering, Federal University of Technology, Minna, Niger State, Nigeria.
PLoS One. 2022 Jul 18;17(7):e0269935. doi: 10.1371/journal.pone.0269935. eCollection 2022.
There are many advantages to liquid-based hydrothermal carbonization (L-HTC) but the need to immerse the biomass in water generates more post-process water, hindering the commercialisation of HTC. To address this issue, this study investigated the feasibility of vapour-based HTC (V-HTC), which minimizes the water required. Dairy manure was hydrothermally treated at temperatures of 200, 230, 255 and 270°C and biomass-to-water ratios (B/W) of 0.1, 0.18, 0.25, 0.43, 0.67 and 1.0 for 20 minutes, then the produced hydrochars were characterized by calorific, proximate, ultimate and thermogravimetric analyses. The results showed that the mass yields of hydrochar decreased with increasing temperature but were essentially stable at high B/W ratios. Notably, the calorific values of the hydrochars increased with increasing temperature and B/W ratio, and the energy density increased by 46%. Due to the higher mass yield and increased energy density, maximum energy yields at each temperature (86.0-97.4%) were observed at a B/W ratio of 1.0. The proximate and ultimate analyses revealed that the degree of coalification, such as the increase in carbon content and decrease in oxygen and volatile matter, progressed more under V-HTC than L-HTC conditions, likely because the lower liquid content in V-HTC facilitates the formation of secondary char and increases the reaction severity due to higher acidity. This study showed a potential approach for upgrading a semi-solid-state biomass by V-HTC.
基于液体的水热碳化（L-HTC）有许多优点，但需要将生物质浸入水中会产生更多的后处理水，从而阻碍 HTC 的商业化。为了解决这个问题，本研究探讨了蒸气基 HTC（V-HTC）的可行性，该方法可将所需水量降至最低。在 200、230、255 和 270°C 的温度下，以 0.1、0.18、0.25、0.43、0.67 和 1.0 的生物质与水的比例（B/W），对乳牛粪便进行了 20 分钟的水热处理，然后通过热值、近似分析、最终分析和热重分析对产生的水热炭进行了表征。结果表明，水热炭的质量产率随温度升高而降低，但在高 B/W 比下基本稳定。值得注意的是，水热炭的热值随温度和 B/W 比的增加而增加，能量密度增加了 46%。由于较高的质量产率和增加的能量密度，在每个温度下（86.0-97.4%），在 B/W 比为 1.0 时观察到最大的能量产率。在接近和最终分析中发现，煤化程度，如碳含量的增加和氧和挥发物的减少，在 V-HTC 条件下比在 L-HTC 条件下更为明显，这可能是因为 V-HTC 中较低的液体含量有利于二次炭的形成，并由于较高的酸度而增加反应的剧烈程度。本研究表明了一种通过 V-HTC 升级半固态生物质的潜在方法。
