Role of ambient pressure in self-heating torrefaction of dairy cattle manure

This paper describes the role of ambient pressure in self-heating torrefaction of livestock manure. We explored the initiating temperatures required to cause self-heating of wet dairy cattle manure at different ambient pressures (0.1, 0.4, 0.7, and 1.0 MPa). Then, we conducted proximate, elemental, and calorific analyses of biochar torrefied at 210, 250, and 290 °C. The results showed that self-heating was induced at 155 °C or higher for 0.1 MPa and at 115 °C or lower for 0.4 MPa or higher. The decrease of the initiating temperature at elevated pressure was due not only to more oxygen, but also to the retention of moisture that can promote chemical oxidation of manure. Biochar yields decreased with increasing torrefaction temperature and pressure, and the yield difference at 0.1 and 1.0 MPa was more substantial at lower temperatures: a 29.8, 16.4, and 9.4% difference at 210, 250, and 290 °C, respectively. Proximate and elemental analyses showed that elevated pressure promotes devolatili...

本文阐述了环境压力在畜禽粪便自加热烘焙（torrefaction）过程中的作用。我们探究了不同环境压力（0.1、0.4、0.7及1.0 MPa）下，湿奶牛粪便发生自加热所需的起始温度。随后，我们对在210、250及290摄氏度下烘焙得到的生物炭（biochar）进行了工业分析、元素分析及热值分析。结果表明，在0.1 MPa压力下，155摄氏度及以上可引发自加热；而在0.4 MPa及更高压力下，115摄氏度及以下即可引发自加热。高压下起始温度降低，不仅归因于氧气含量增加，还与水分的保留有关——水分可促进粪便的化学氧化。生物炭产率随烘焙温度和压力的升高而降低；在较低温度下，0.1 MPa与1.0 MPa压力下的产率差异更为显著：210、250及290摄氏度下的差异分别为29.8%、16.4%和9.4%。工业分析与元素分析显示，高压可促进脱挥发分...