Techno-economic analysis of production of bio-oil from catalytic pyrolysis of olive mill wastewater sludge with two different cooling mechanisms

Abstract

• A kinetic Aspen Plus model for pyrolysis of olive mill wastewater sludge. • Successful validation model with experimental results. • Calculates pyrolysis yields as a function of temperature. • A techno-economical study for a plant capacity of 100 tonnes/day for two schemes. • Monte-Carlo sensitivity analysis. A techno-economic analysis of production of bio-oil from catalytic pyrolysis of olive mill wastewater sludge has been performed with two different cooling schemes. The two configurations differ in the manner how the bio-oil vapors are quenched. In scheme-1, a vapor compression refrigeration machine is utilized for condensation of bio-oil vapors while in scheme-2, the vapor compression refrigeration machine is replaced by absorption refrigeration machine. The two schemes are modelled in Aspen Plus which provides mass and energy balances. For techno-economic analysis, Aspen process economic analyzer is employed. The model is first validated against experimental data from lab scale and then upscaled to an industrial scale of 100 tonnes/day wet biomass (93 tonnes/day dry biomass). Results show that the model with absorption refrigeration machine (scheme-2) has a slightly better process efficiency and a lower MFSP compared to the model with compression refrigeration machine (scheme-1). Total anticipated capital investment expenses for scheme-1 and scheme-2, comprising plant fixed capital investment (FCI), start-up, working capital, and interest, are expected to be €22.1 M and €17.5 M, respectively. The equipment costs are based on first quarter of 2021 and the economic life of the project is 20 years. Monte Carlo sensitivity analyses showed that the bio-oil MFSP is most vulnerable to discounted cash flow, income tax and bio-oil yield. The production cost of bio-oil varies between €2.16/GGE and €6.19/GGE for scheme-1 and €1.78/GGE and €5.01/GGE for scheme-2 when cost parameters are varied within an industrially relevant range. The findings support the viability of producing bio-oil by catalytic fast pyrolysis on a commercial scale.