Walnut Shell Pretreatment in Regard to Its Combustion Properties

Area of Science:

• Sustainable Energy
• Biomass Utilization
• Combustion Science

Background:

• Growing demand for alternative energy due to fossil fuel shortages and greenhouse gas (GHG) emission reduction targets.
• Waste biomass presents a viable, eco-friendly, and weather-independent renewable energy source.
• Underutilization of many biomass types in current energy and heating industries.

Purpose of the Study:

• To evaluate the potential of walnut shells as a novel biomass fuel for heating applications.
• To analyze the combustion properties and flue gas emissions of walnut shell pellets.
• To determine the optimal drying conditions (temperature and time) for maximizing the heating value of walnut shell biomass.

Main Methods:

• Pelletization of walnut shells for use in domestic heating boilers.
• Combustion analysis of walnut shell pellets, including flue gas analysis for CO, NOx, CH4, and H2S.
• Experimental determination of the effect of drying temperature and time on biomass heating value.

Main Results:

• Walnut shell pellets achieved a high calorific value of 16.90 MJ/kg.
• The produced pellets exhibited a low ash content of 1.31% and moisture content of 8.25%.
• Optimal drying conditions were identified as 110 °C for 90 minutes, yielding the best heating value.

Conclusions:

• Walnut shells are a suitable and high-performing biomass material for pellet production.
• The combustion properties of walnut shell pellets are comparable, and in some aspects superior, to commercially available wood pellets.
• Drying parameters significantly influence the final calorific value, with specific conditions optimizing fuel performance.