Effects of pyrolysis parameters on the distribution of pyrolysis products of Miscanthus

This work presents a comprehensive study on the effects of pyrolysis parameters (pyrolysis temperature, residence time, and heating rate) on the distribution of pyrolysis products of Miscanthus. Py-GC/MS (Pyrolysis-gas chromatography/mass) was conducted to identify building blocks of value-added chemical from Miscanthus. The results showed that the main pyrolysis products of Miscanthus were ketone, aldehyde, phenol, heterocycles, and aromatic compounds. The representative compounds of ketone and aldehyde compounds produced at different pyrolysis temperatures changed obviously, while the representative compounds of phenolic, heterocyclic, and aromatic compounds had no obvious change. Large-scale pyrolysis of Miscanthus had begun at 400°C, and the relative content of pyrolysis products from Miscanthus reached the maximum of 98.34% at 700°C. The relative peak area ratio of phenol and aromatic compounds reached the maximum and minimum at the residence time of 5 and 10 s, while the relative peak area ratio of ketone compounds showed the opposite trend. The relative peak area ratio of aldehyde compounds was higher under shorter or longer residence time. For heterocyclic compounds, the relative peak area ratio reached the maximum of 27.0% at residence time of 10 s. The faster or slower heating rate was beneficial to the production of aldehyde and phenol compounds. The relative peak area ratio of ketone compounds reached the maximum at 10,000°C/s, 70°C/s, and 10°C/s, and the relative peak area ratio tendency of heterocyclic compounds was similar to ketone. For aromatic compounds, the overall fluctuations were large, and the relative peak area ratio was the highest at the heating rate of 100°C/s.

Co-combustion performance analysis of a Fujian anthracite with Cunninghamia lanceolate and Mycorrhizal plants

The co-combustion characteristics of Fujian anthracite with two biomasses (i.e. Cunninghamia lanceolata) and Mycorrhizal plants in different proportions were investigated using thermogravimetric analysis. The result showed that first, the co-combustion processes of Fujian anthracite with the two biomasses ( Cunninghamia lanceolata and Mycorrhizal plants) proceeded in three stages, separation and combustion of volatiles, combustion of fixed carbon in the biomass, and combustion of fixed carbon in Fujian anthracite. Secondly with increasing proportion of biomass, the co-combustion of Fujian anthracite with Cunninghamia lanceolata and Mycorrhizal plants shifted to a low-temperature zone, with a lower ignition temperature, shortened burnout time, and growth of both combustibility index ( Ci) and comprehensive combustion index S. Finally, at different mixing proportions, the comprehensive combustion index S during co-combustion of FW with Mycorrhizal plants is always larger than that during co-combustion with Cunninghamia lanceolata; therefore, FW and Mycorrhizal plants exhibit superior comprehensive co-combustion performance to FW and Cunninghamia lanceolata. Analysis of various parameters pertaining to combustion performance shows that the ignition and combustion performance of Fujian anthracite was improved as long as the Fujian anthracite was mixed with around 20% biomass.