GROUP 2.4 -
Pyrolysis is the chemical reaction performed by heating wood or biomass without burning it. Discovered thousands of years ago and commonly used to make charcoal, it is not an overly complex or new reaction. However, in recent years, new applications for pyrolysis have been realized, and interest has been growing in how it can be implemented. When pyrolyzing biomass in the right conditions, the reaction produces a solid biochar, which has many valuable properties. The most prominent use for it is as a fertilizer, which helps retain water and prevent nutrients from being washed away. Additionally, as a low emission process, with an almost net-neutral energy cost, the reaction itself is environmentally friendly and could be added to existing processes relatively easily. With these new developments in mind, the hazelnut industry has a great potential to benefit. As hazelnuts are prepared, the shells are usually considered a waste stream and sold for pennies per ton. By pyrolyzing these shells before selling, both their usefulness and value will skyrocket.
Pyrolysis is a unique reaction, in that the many process variables involved can have extreme impacts on the reaction performance. The potential outcomes of pyrolysis in different conditions are so varied, they can almost be considered different reactions. The teams investigated reaction was intermediate – slow pyrolysis; the reaction takes place over the course of 35 minutes, with the raw shells being slowly heated from room temperature to about 350° C. Under these conditions, the primary product is biochar, at 55% mass yield. Two other components also form, being a crude biooil (32% mass) and syngas (8%). After separating the liquids from the solids, the char and oil can both be sold, with the char being the main profit stream. The crude oil will be sold relatively cheaply, considering the intensive processing still necessary to make it useable. The syngas (synthetic gas) is largely recycled back into the process as both a fuel and a sweep gas. Like natural gas, syngas can be burned, although it outputs roughly ¼ the amount of energy. Regardless, enough is produced to fully heat the reactor when burned as a fuel. Syngas is also used as a sweep, pumped into the reaction chamber to ideally progress the pyrolysis reaction a bit further than it would under a nitrogen atmosphere. For more details on hazelnut pyrolysis and our proposed reactor design, please attend the expo on June 4th!
