Calculation Of The Heating Value Of Wood Fuel From The Elemental Composition

The heating value is the main quality indicator of solid fuel, which can be calculated on the basis of its elemental composition. The accuracy of the heating value calculation of wood fuel by the available universal equations is insufficient (over 2 %). The article presents the results of the determination of ash (at 800 degrees C), heating value and elemental composition (carbon, hydrogen, oxygen, sulfur and nitrogen) for 43 different samples. The elemental composition data of wood fuel from different literary sources are analyzed: the higher content of carbon and hydrogen is characteristic for the data of the end of the 19th century. According to 11 equations the paper presents the results of the calculation of the high heat value of wood fuel in an absolutely dry state. The equations, which take into account the main component contribution (carbon) with the adjustment by a free member or by a minor contribution of hydrogen, are the most optimal for the calculation of this index. By the method of minimum squares and with the use of the experimental data of 35 samples we perform the coefficients calculation of carbon and hydrogen and propose an equation to calculate the high heat value of wood fuel in a completely dry state. The test of equation is carried out on the basis of the experimental data for 28 samples from three different literary sources. The average absolute deviation of the calculated and experimental values (calculation error) is 1.5 %, which corresponds to the peak error of the calorimetric test of the high heat value. The hydrogen and carbon content is advisable to determine simultaneously using the automatic elemental analyzers; and the hydrogen content should be used to calculate a low heat value.