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Thermodynamic modelling of biomass based power production

Bjäreborn, Emil and Åkerman, Fredrik (2010)
Department of Energy Sciences
Abstract
With today’s growing awareness of human caused climate changes there is a big interest to replace fossil fuels with renewable fuel sources, such as biomass fuels. For power production biomass are traditionally combusted in small scale facilities which uses a steam cycle. The electrical efficiencies for such facilities are relatively low. By gasifying the solid biomass to syngas it can be used for running a gas turbine. The gas turbine can then be combined with a steam cycle which could increase the electrical efficiency. The purpose of this master thesis was to investigate the electrical efficiency of biomass integrated gasification combined cycle and compare this to current facilities using the Rankine-cycle. The work was carried out in... (More)
With today’s growing awareness of human caused climate changes there is a big interest to replace fossil fuels with renewable fuel sources, such as biomass fuels. For power production biomass are traditionally combusted in small scale facilities which uses a steam cycle. The electrical efficiencies for such facilities are relatively low. By gasifying the solid biomass to syngas it can be used for running a gas turbine. The gas turbine can then be combined with a steam cycle which could increase the electrical efficiency. The purpose of this master thesis was to investigate the electrical efficiency of biomass integrated gasification combined cycle and compare this to current facilities using the Rankine-cycle. The work was carried out in two steps, the first step was a literature survey and the second step was to model an integrated gasification combined cycle plant. The literature survey covered different gasification technologies, gas turbine operation, gas cleaning, fuel drying etc. Equilibrium modelling of the gasification process was also investigated in the literature survey. From the survey the concept of pressurized indirect gasification was chosen for the second part of the work. The models and simulations are made with the software IPSEpro, which is a simulation environment for energy engineering. The air needed for the combustion chamber in gasifier was supplied from the gas turbine’s compressor. The drained mass flow corresponded well to the increase in the fuel mass flow to the gas turbine. The mass flow through the turbines thereby was kept close to the design case. When fuel drying was integrated this lead to a reduction in the power output but the electrical efficiency increased. The increase is explained by the fact that the efficiency is calculated on the lower heating value of the fuel. The results for the electrical efficiencies were in the region of 45-50% which is higher than for conventional power plants using biofuels. However an integration of a gasification unit will create a very advanced system. Finally the gasifier model was adjusted for atmospheric operation. This resulted in lowered electrical efficiencies compared to those of the pressurized configuration. (Less)
Please use this url to cite or link to this publication:
author
Bjäreborn, Emil and Åkerman, Fredrik
supervisor
organization
year
type
H1 - Master's Degree (One Year)
subject
keywords
biomass fuels gas turbine steam cycle
report number
ISRN LUTMDN/TMHP--10/5202--SE
ISSN
0282-1990
language
English
id
1549821
date added to LUP
2010-02-23 14:14:21
date last changed
2010-02-23 14:14:21
@misc{1549821,
  abstract     = {With today’s growing awareness of human caused climate changes there is a big interest to replace fossil fuels with renewable fuel sources, such as biomass fuels. For power production biomass are traditionally combusted in small scale facilities which uses a steam cycle. The electrical efficiencies for such facilities are relatively low. By gasifying the solid biomass to syngas it can be used for running a gas turbine. The gas turbine can then be combined with a steam cycle which could increase the electrical efficiency. The purpose of this master thesis was to investigate the electrical efficiency of biomass integrated gasification combined cycle and compare this to current facilities using the Rankine-cycle. The work was carried out in two steps, the first step was a literature survey and the second step was to model an integrated gasification combined cycle plant. The literature survey covered different gasification technologies, gas turbine operation, gas cleaning, fuel drying etc. Equilibrium modelling of the gasification process was also investigated in the literature survey. From the survey the concept of pressurized indirect gasification was chosen for the second part of the work. The models and simulations are made with the software IPSEpro, which is a simulation environment for energy engineering. The air needed for the combustion chamber in gasifier was supplied from the gas turbine’s compressor. The drained mass flow corresponded well to the increase in the fuel mass flow to the gas turbine. The mass flow through the turbines thereby was kept close to the design case. When fuel drying was integrated this lead to a reduction in the power output but the electrical efficiency increased. The increase is explained by the fact that the efficiency is calculated on the lower heating value of the fuel. The results for the electrical efficiencies were in the region of 45-50% which is higher than for conventional power plants using biofuels. However an integration of a gasification unit will create a very advanced system. Finally the gasifier model was adjusted for atmospheric operation. This resulted in lowered electrical efficiencies compared to those of the pressurized configuration.},
  author       = {Bjäreborn, Emil and Åkerman, Fredrik},
  issn         = {0282-1990},
  keyword      = {biomass fuels
gas turbine
steam cycle},
  language     = {eng},
  note         = {Student Paper},
  title        = {Thermodynamic modelling of biomass based power production},
  year         = {2010},
}