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The state of Oregon grows and processes roughly 65,000 tons of hazelnuts every year leaving 28,500 tons of shells to be dealt with. Some of these shells end up as landscaping materials where they can slightly increase the water retention of the soil and deter snails from crossing over the area due to the sharp edges on the cracked shells. Another outlet for the shells is livestock feed where they are ground up and supplemented into existing feed. The typical price for hazelnut shells in these applications is $7.5 per ton. However, the focus of this project is on the conversion of hazelnut shells into biochar which can be used as a soil additive and possesses a higher sale price of $2100-$2500 per ton. The addition of biochar can increase the water and nutrient retention of the soil by up to 22% while also changing the pH of the soil to increase the amount of nutrients absorbed by the plants, increasing crop yields.

Biochar is made through a process called pyrolysis in which biomass is heated in a low oxygen environment which causes the pyrolytic reaction to take place, thermally decomposing the material.The main products of this reaction are bio-oil which is an energy rich hydrocarbon and biochar. Our team has designed a theoretical pyrolytic reactor for a hazelnut processing company which takes the shells and converts them into these more beneficial products. The reactor operates by sending mostly hot nitrogen, carbon dioxide, and water vapors that were created in a combustion reaction at a temperature of approximately 230℃ into the bottom of a 13 m³ reactor vessel filled with 11,000 kg of dried hazelnut shells in a single batch. The hot gases meet the packed bed of shells where they are heated for approximately 10 minutes during which the shells undergo the pyrolytic reaction and are converted into biochar. The exhaust gas of the reactor which now contains bio-oil as well can then be fed back into the combustion reaction to heat more gas to continue the pyrolysis reaction in a more energy efficient manner. With the addition of this system to the processing plant, the rather benign hazelnut shells can be converted into a more versatile material that can improve soil quality and drastically increase overall revenue.