Study of the Briquetting Process of Walnut Shells for Pyrolysis and Combustion

Walnut shells can be used as fuels in power plants directly or biochars obtained by pyrolysis torrefaction. They are an example of clean waste biomass which shows a low ash content and high Net Calorific Value, making them excellent for energy recovery industrial non-industrial applications, such bakeries, restaurants, homes. Their main inconvenience is their bulk density. Densification possible solution that reduces the costs transportation, handling, storage. In this work, after characterization walnut shells, briquettes were using hydraulic piston press briquette machine under different conditions to find best quality without need previous grinding pelletizing. This method features easy operation maintenance, shape could adapted desired. The was measured through density durability. After fixing compaction pressure obtain acceptable briquettes, factors affecting studied: operating temperature, moisture content, presence small amounts walnuts. Good with 66 MPa, densities around 1040 kg/m3, durabilities higher than 94% when process carried at 140 °C. greatest increase durability observed between room temperature those 80 walnuts, common shelling process, improved Although water necessary, from only 1% showed better durabilities. Therefore, suitable obtaining good according specifications solid biofuels established standards, any pretreatment.