In-situ upgrading of Napier grass pyrolysis vapour over microporous and hierarchical mesoporous zeolites

This study presents in-situ upgrading of pyrolysis vapour derived from Napier grass over microporous and mesoporous ZSM-5 catalysts. It evaluates effect of process variables such catalyst–biomass ratio and catalyst type in a vertical fixed bed pyrolysis system at 600 °C, 50 °C/min under 5 L/min nitrogen flow. Increasing catalyst–biomass ratio during the catalytic process with microporous structure reduced production of organic phase bio-oil by approximately 7.0 wt%. Using mesoporous catalyst promoted nearly 4.0 wt% higher organic yield relative to microporous catalyst, which translate to only about 3.0 wt% reduction in organic phase compared to the yield of organic phase from non-catalytic process. GC–MS analysis of bio-oil organic phase revealed maximum degree of deoxygenation of about 36.9% with microporous catalyst compared to the mesoporous catalysts, which had between 39 and 43%. Mesoporous catalysts promoted production olefins and alkanes, normal phenol, monoaromatic hydrocarbons while microporous catalyst favoured the production of alkenes and polyaromatic hydrocarbons. There was no significant increase in the production of normal phenols over microporous catalyst due to its inability to transform the methoxyphenols and methoxy aromatics. This study demonstrated that upgrading of Napier grass pyrolysis vapour over mesoporous ZSM-5 produced bio-oil with improved physicochemical properties

Heat integration for bio-oil hydroprocessing coupled with aqueous phase steam reforming

Optimized heat exchanger networks can improve process profitability and minimize emissions. The aim of this study is to assess the heat integration opportunities for a hypothetical bio-oil hydroprocessing plant integrated with a steam reforming process via pinch technology. The bio-oil hydroprocessing plant was developed with rate based chemical reactions using ASPEN Plus® process simulator. The base case is a 1600 kg/h bio-oil hydroprocessing plant, which is integrated with a steam reforming process of the bio-oil aqueous phase. The impact of the reformer steam to carbon ratio on energy targets was analysed, revealing that significant energy savings can be achieved at different process variations. Aspen Energy Analyzer™ was employed to design the heat exchanger network. Two heat exchanger network designs are considered. The optimum design reveals that the second hydrodeoxygenation reactor effluent can preheat the bio-oil feed with minimal capital cost implication and achieve similar energy targets compared with the alternative design. The economic and environmental implications of the two heat exchanger network designs on product value were also evaluated

Techno-economic performance analysis of biofuel production and miniature electric power generation from biomass fast pyrolysis and bio-oil upgrading

The techno-economic performance analysis of biofuel production and electric power generation from biomass fast pyrolysis and bio-oil hydroprocessing is explored through process simulation. In this work, a process model of 72 MT/day pine wood fast pyrolysis and bio-oil hydroprocessing plant was developed with rate based chemical reactions using Aspen Plus® process simulator. It was observed from simulation results that 1 kg s−1 pine wooddb generate 0.64 kg s−1 bio-oil, 0.22 kg s−1 gas and 0.14 kg s−1 char. Simulation results also show that the energy required for drying and fast pyrolysis operations can be provided from the combustion of pyrolysis by-products, mainly, char and non-condensable gas with sufficient residual energy for miniature electric power generation. The intermediate bio-oil product from the fast pyrolysis process is upgraded into gasoline and diesel via a two-stage hydrotreating process, which was implemented by a pseudo-first order reaction of lumped bio-oil species followed by the hydrocracking process in this work. Simulation results indicate that about 0.24 kg s−1 of gasoline and diesel range products and 96 W of electric power can be produced from 1 kg s−1 pine wooddb. The effect of initial biomass moisture content on the amount of electric power generated and the effect of biomass feed composition on product yields were also reported in this study. Aspen Process Economic Analyser® was used for equipment sizing and cost estimation for an nth plant and the product value was estimated from discounted cash flow analysis assuming the plant operates for 20 years at a 10% annual discount rate. Economic analysis indicates that the plant will require £16.6 million of capital investment and product value is estimated at £6.25/GGE. Furthermore, the effect of key process and economic parameters on product value and the impact of electric power generation equipment on capital cost and energy efficiency were also discussed in this study

Heat integration for bio-oil hydroprocessing coupled with aqueous phase steam reforming

Optimized heat exchanger networks can improve process profitability and minimize emissions. The aim of this study is to assess the heat integration opportunities for a hypothetical bio-oil hydroprocessing plant integrated with a steam reforming process via pinch technology. The bio-oil hydroprocessing plant was developed with rate based chemical reactions using ASPEN Plus® process simulator. The base case is a 1600 kg/h bio-oil hydroprocessing plant, which is integrated with a steam reforming process of the bio-oil aqueous phase. The impact of the reformer steam to carbon ratio on energy targets was analysed, revealing that significant energy savings can be achieved at different process variations. Aspen Energy Analyzer™ was employed to design the heat exchanger network. Two heat exchanger network designs are considered. The optimum design reveals that the second hydrodeoxygenation reactor effluent can preheat the bio-oil feed with minimal capital cost implication and achieve similar energy targets compared with the alternative design. The economic and environmental implications of the two heat exchanger network designs on product value were also evaluated