Evaluation of the Apple Pomace Use as a Raw Material for Alternative Solid Fuel

Abstract

The paper presents the possibility of evaluation of using apple pomace as an alternative solid fuel. Taking into account the high initial moisture content of the raw material, preliminary drying using a highly efficient filtration drying method is proposed. Based on the experimental data, the following were determined: generalized dependencies describing the change in the moisture content of raw materials and the drying duration; dependence of hydraulic resistance on the stationary layer height of the material during the filtration drying process; technologically feasible parameters of filtration drying (layer height of the dried material 120 mm, temperature of the thermal agent 90 °C, velocity of the thermal agent 1.76 m/sec); energy consumption for the removal of 1 kg of moisture under these process parameters is 21990.02 kJ/kg H2O or 6.11 kW h/kg H2O. An estimated calculation of the industrial drying of apple pomace from a moisture content of 83 % wt. to 14 % wt. by the filtration method in terms of drying ≈ 1000 kg of raw materials established the total energy consumption for removing 1 kg of moisture of 6.36 kW h/kg H2O, and the total amount of energy required for the drying process of 92977.11 kJ/kg dry mat. For comparison, an estimated calculation of apple pomace drying in a rotary dryer was performed, which showed the advantage of the filtration method. The samples of briquetted solid fuel from dried apple pomace were made and their main characteristics were investigated: higher calorific value (≈ 19438 kJ/kg), residual moisture content (< 1 % wt.), ash content (≈ 0.55 % wt.). The compliance of the created briquettes characteristics with the requirements of existing European standards for solid fuels is shown. With rational preliminary preparation of secondary raw materials of plant origin, their use as solid fuels can become an alternative to slowly renewable or non-renewable fuel sources, solve the problem of accumulation of industrial waste with a limited shelf life, and generally improve the environmental situation.

Keywords

• biomass; apple pomace; secondary raw materials; drying; alternative solid fuel;