Jens Wolf

Performance Analysis of Evaporative Biomass Air Turbine Cycle With Gasification for Topping Combustion

This paper investigates the performance of a new power cycle, a so called evaporative biomass air turbine (EvGT-BAT) cycle with gasification for topping combustion. The process integrates an externally fired gas turbine (EFGT), an evaporative gas turbine (EvGT), and biomass gasification. Through such integration, the system may provide the potential for adapting features from different advanced solid-fuel-based power generation technologies, e.g., externally fired gas turbine, integrated gasification combined cycle (IGCC), and fluidized bed combustion, thus improving the system performance and reducing the technical difficulties. In the paper, the features of the EvGT-BAT cycle have been addressed. The thermal efficiencies for different integrations of the gasification for topping combustion and the heat recovery have been analyzed. By drying the biomass feedstock, the thermal efficiency of the EvGT-BAT cycle can be increased by more than three percentage points. The impact of the outlet air temperature of the high-temperature heat exchanger has also been studied in the present system. Finally, the size of the gasifier for topping combustion has been compared with the one in IGCC, which illustrates that the gasifier of the studied system can be much smaller compared to IGCC. The results of the study will be useful for the future engineering development of advanced solid fuel power generation technologies.

Techno-economic assessment of catalytic gasification of biomass powders for methanol production

This study evaluated the techno-economic performance and potential benefits of methanol production through catalytic gasification of forest residues and lignin. The results showed that while catalytic gasification enables increased cold gas efficiencies and methanol yields compared to non-catalytic gasification, the additional pre-treatment energy and loss of electricity production result in small or no system efficiency improvements. The resulting required methanol selling prices (90-130€/MWh) are comparable with production costs for other biofuels. It is concluded that catalytic gasification of forest residues can be an attractive option as it provides operational advantages at production costs comparable to non-catalytic gasification. The addition of lignin would require lignin costs below 25€/MWh to be economically beneficial.

Simulation of Steam-Based Gasification Processes for Topping Combustion in the Biomass Air Turbine (BAT) Cycle

In this work, steam-based gasification is investigated as a technology for fuel gas production for topping combustion in a biomass air turbine (BAT) cycle. For different systems, based on flash or conventional pyrolysis, the characteristics of the product gas quality are studied. The gas composition and the heating value of the produced gas are simulated by changing the main system parameters such as the moisture content of the biomass, the operating temperature and the composition of the biomass.A model of the gasification process has been developed to evaluate each process. The model is based on mass conservation, the thermodynamic equilibrium of the water-gas-shift reaction and the methane yield during pyrolysis.A gasification system with flash pyrolysis is identified as a promising technology for fuel gas production for use in topping combustion. The major features of the system are: first, the system provides a gas with a heating value of near to 16 MJ/Nm3 and small amounts of nitrogen gas; second, the application of a water knock out unit eliminates the influence of the water content in the feedstock on the product gas quality; third, the gasification process can be conducted in a tubular reactor within the furnace of the BAT cycle. This reduces the number of reactors and keeps the costs low.Copyright