| Biomass charcoal briquette has low processing cost, convenient storage and transportation, combustion performance, high thermal efficiency, smokeless combustion etc. Therefore, research on biomass carbonization and briquette quality characteristics have realistic meaning to the protection of the ecological environment and forest resources as well as development and utilization of biomass charcoal with high quality. Particularly, industrial analysis components and calorific value are important indexes to measure the quality of biomass fuel. The conventional chemical analysis have cumbersome procedures and a heavy workload, It requires skilled workers, and cannot meet the requirements of on-line analysis. Therefore, the industry urgently needs rapid determination method or detection device for testing the components and calorific value of biomass raw materials.Three common agricultural and forestry biomass feedstocks; pine wood, cedar wood and cotton stalk were chosen as the research subjects. Referring to the proximate analysis of these products, we used spectrum technology combined with the chemometrics modeling method, and established the rapid determination of biomass raw material moisture, volatile matter, ash content, fixed carbon content and calorific value of mathematical prediction model. On the basis of the research of carbonization process conditions, this paper analyzed the influence of carbonization process parameters such as raw material, different volume of material and max temperature to the physical and chemical performance including volatile matter, ash, fixed carbon content and calorific value, char yield and energy yield. The main research contents and conclusions are as follows:(1) Rapid determination of componential contents and calorific value of selected agricultural biomass feedstocks using spectroscopical technologyIn this study, visible and near-infra (vis-NIR) spectroscopy was employed to build prediction models of componential contents and calorific value of three selected species of agricultural biomass feedstock, i.e. pine wood, cedar wood, and cotton stalk. The PLS cross validation results showed that compared with original reflection spectra, partial least square (PLS) regression models developed for first derivative spectra produced higher prediction accuracy while the models are relatively simple. It is found that the ash, volatile matter and moisture were tested with high precision which was suitable for the practical use. And test of the fixed carbon and calorific value were resulted relatively low, but can still be used for biomass feedstock classification.(2) Effects of temperature and loading rate on the performance of the carbonization and the characteristics of biomass carbonizationIn this study, the factor of carbonization temperature and loading rate affecting the physical and chemical performance was analyzed by the carbonization of pine wood, cedar wood and cotton stalk in a muffle furnace and lab made carbonization installation. Between the temperatures of300-600℃, the carbonization was a gradually pyrolytic process on volatile, and on this basis, each feature changed with the carbonization temperature change. With the increase of temperature, the quality of carbonization continuously improved, and when the temperature reached to500℃, heat productivity of the three carbonization measurements were as high as28.629MJ/kg,27.900MJ/kg and26.368MJ/kg, which reached the standard as a high calorific value coal. The char yield and total energy yield decreased with the increase of temperature, and under the laboratory conditions, increasing the load of raw material, not only greatly increased the quality of carbonized product, but also increased energy yield.(3) Effects of Cassava starch adhesives and lignin derivatives on the mechanical properties of biomass charcoal briquetteExplore the impact on the rheological properties of cassava starch by changing the conditions of the starch content of the adhesive, temperature and shear rate. To the chemically modified tapioca starch, the viscosity increases as the temperature rises, and when the shear rate increases, the shear stress increases but the viscosity decreases, showing a pseudo plastic fluid shear-thinning phenomenon.The charcoal briquette compressive strength or shatter resistance increased with the increase of adhesive content, and both presented a good linear relationship. The better amount of adhesive in pine wood and cotton stalk charcoal briquette was27.5%, and was30%in cedar wood charcoal briquette.Lignin derivatives increased varying degrees of pine, fir and cotton stalks charcoal briquette radial compression heat intensity and defensive broken heat intensity, especially the most obvious loose charcoal briquette, whose radial compressive thermal strength nearly increased56kPa, while residual mass percentage and maximum block mass percentage increased from71.8%and68.8%to96.5%and88.1%. |
