Technic-economic analysis of pyrolysis to produce fuel oil

Resumo

It was made a technic-economic analysis of the feasibility of implementing a pyrolysis plant for the production of fuel oil (FO) from plastic fractions of Municipal Solid Waste (MSW). The catalytic pyrolysis process is carried out in a fixed bed reactor with a capacity of 4 m³ loaded with crushed and dry plastic waste (volumetric mass of 500 kg/m³), which is heated at a rate of 2 °C/min until the reaction temperature reaches 270 and 350 °C. Then, the pyrolysis process is then maintained at the established temperature for 6 hours. The retention time of the pyrolysis gases is 90 minutes. Each batch operation cycle lasts an average of 9 hours. It was evaluated production of FO from different plastic fractions resulting from MSW sorting in a medium-sized municipality. In scenario 1 (reference scenario), 1.04 and 3.63 ton/day of plastics of the MSW (PSW) are sent to recycling and landfill, respectively. Three alternative scenarios were defined and analyzed to implement plastic pyrolysis: scenario 2, 3.63 ton/day, the fraction of non-recycled PSW is considered for processing by pyrolysis; scenario 3, it is considered the recycling of PET and PVC, and the remaining PSW represents 4.36 ton/day, and it is considered for processing by pyrolysis; scenario 4, it is maintained the 4.36 ton/day of PSW as valorized by pyrolysis, and it is assumed that an additional 0.64 ton/day of PSW comes from an external source. The FO production costs were estimated at 1.50, 1.29, and 1.13 R$/L, approximately 41%, 49%, and 56% lower than the FO sale price (2.55 R$/L), for scenarios 2, 3, and 4, respectively. Costs of production per unit of energy (GJ) in FO are between 40.88 and 29.67 R$/GJ. The Net Present Value (NPV) of the solution, considering scenarios 2 to 4, increased from R$ 6.72×10⁶ to R$ 11.29×10⁶. The positive NPV for the scenarios 2 to 4 indicates the economic viability of the pyrolysis plant. The pyrolysis system would need to operate between three and four years to recover the invested capital. The costs of the municipality with the destination of MSW can be reduced in 54.75%, from 139.48 to 63.12 R$/ton MSW, between the reference scenario and scenario 4.