Papers by Keyword: Combustion Characterization

Abstract: Coconut fiber (CF) and eucalyptus leaves (EL) were upgraded by hydrothermal carbonization (HTC) and fuel qualities of corresponding hydrochars were determined in the present study. Compared to raw biomass, the hydrochars have increased energy density, and the decreased nitrogen and sulfur contents showed that reduced pollutant emissions are produced during hydrochar combustion. The ignition temperatures of hydrochars were higher and the combustion also shifted to higher temperature ranges. In addition, HTC significantly reduced the slagging and fouling tendencies of raw biomass and the fouling index of CF and EL changed from 2.59 to 0.09 and 1.11 to 0.24, respectively. This study demonstrated that solid fuel with high quality can be produced by HTC and improved thermal efficiency and environmental benefits can be achieved by hydrochar combustion.

Abstract: Small-scale burning experimental study of computer monitors and paper was done based on cone calorimeter. The small and middle scale fires were simulated by changing the heat radiation intensity of cone calorimeter. The heat release rate, mass loss rate and production rate of CO was measured in experiment. The data of mass loss rate and CO production rate is fitted, and the formula of its change with time is obtained. The computer monitor has slow pyrolysis speed on the 35 kW/m², and the carbon layer on surface gradually thickened. So the heat will accumulate, and then the pyrolysis speed increases. The heat release rate reaches to the second peak. The fire growth index of monitor increases as the heat radiation intensity. But the fire growth index of paper has the opposition trend. The CO production rate of computer monitor is larger than paper’s. The experiment results can reflect the combustion characteristics of computer monitor on real fires.

Abstract: The combustion characteristics of coal and biomass blends with adding adsorbing sulfur agent was investigated using thermogravimetric analyzer. The results indicated that the combustion process of the blends were similar to that of pure coal and biomass, which there were two apparent weight-loss peaks--one for volatile burning and another for char burning. The combustion stages could be divided into the dewatering period, volatilization and burning, char burning and burnout. Nevertheless, the combustion characteristics of blends varied with the biomass blending ratio and Ca/S ratio. Due to the increase of biomass blending ratio, the volatile matter content of blends increased, which leaded to the increase of peak value for volatile burning stage. In this stage, due to the lower reaction temperature, less SO₂ was produced and the reaction to CaO was slower. With the progress proceeding, char began to be burned and large heat was released and the adsorbing sulfur reactions were becoming stronger. Although the mass of blends reduced fastly, the mass of CaSO₃ and CaSO₄ increased compared to CaO, Which leaded to a wider temperature range of weight-loss for the char burning period. At the same linear temperature gradient, an increase of Ca/S decreased the temperature of volatilization and char burning, and the residue was increased due to more CaO additive. Therefore, the appropriate ratio of Ca/S was necessary to improve the combustion and adsorbing sulfur efficiency. In this study, a basic kinetics analysis for coal and biomass blends is provided. The kinetics parameters reveal that the combustion process of coal and biomass blends with adding absorbing sulfur agent can be described by a first order reaction equation.

Abstract: Alginate calcium fibers were prepared through wet spinning with good tensile strength which can be used for cloth materials. The morphology, mechanical property and combustion property of alginate calcium fibers were investigated. Blending yarns and textile of alginate calcium fibers and combed cotton was fabricated with good hand feeling and strength. Alginate salt fiber was prepared with wet spinning machine designed according to viscose fiber spinning machine. The diameter of alginate calcium fibers was about 10-15µm in diameter with smooth surface. The tensile strength of alginate salt fiber was larger than 4.8 cN in the dry state. The value of Limited Oxygen Index (LOI) of alginate calcium fibers was 34%. The average heat release rates (HRR) of the alginate fiber is about 21 kW/m2 which was much lower than that of most synthetic and natural fibers analysized with Cone. Alginate calcium fibers is an inherent flame-retardant fiber.