| Abstract [eng] |
The major goal of the Master’s thesis is the study of biomass gasification usage in a cogeneration plant. Firstly, a study of biomass (characteristics, advantages and disadvantages), gasification technologies available, biomass gasification process and potential applications has been carried out. The second part of the project is focused on biomass gasifier integration into Vilnius CHP-2 power plant. The gasifier would produce synthetic gases to feed an old BKZ-75-39 boiler that was firing natural gas previously. A Low Temperature Circulating Fluidised Bed gasifier (LT-CFB) was chosen because it is capable to exploit low cost feedstock that contains bigger fraction of alkali metals and other inorganics. Besides, the CFB technology has some commercially successful examples in Finland and Denmark. A gasifier of 70 MW was designed for multiple low cost feedstock, such as straw or peat. The calculations and energy balances were done for the whole technology including gasifier, gas cooler, boiler, turbine, condenser, condensing economizer and district heating network. The overall efficiencies and losses of the system were evaluated. Financial feasibility of the project was evaluated according to investment, fuel and O&M costs as well as revenues from electricity and heat production. It was done according to various assumptions of investment, energy production and electricity price. The Net Present Value was calculated for different cases showing that biomass gasifier integration in Vilnius CHP-2 power plant can be profitable. The environmental impact was estimated. In comparison with natural gas combustion, biomass gasification would lead to reduced emissions of GHG’s and money savings due to CO2 penalty for fossil fuel based energy generation. |
