This project aims at the direct injection of calcium-enriched bio-oil (BioLime) into the post combustion section of, typically, a 10 MWe power plant, in order to desulphurize the flue gas below today's regulations.
Specific objectives are to:
- demonstrate the technique of co-firing of heavy fuel oil and BioLime at 2 Mwth;
- demonstrate 90% sulphur oxides (SOx) removal by applying BioLime;
- demonstrate 50% nitric oxides (NOx) removal by applying BioLime;
- demonstrate reduced CO2 output resulting from cofiring of the biomass derived BioLime;
- develop an optimal bio-oil modification technology (maximum calcium uptake capacity);
- determine the influence of biomass type (wood, straw) on the eventual BioLime quality;
- demonstrate that the ash characteristics remain unchanged upon co-firing of straw-derived BioLime;
- characterize the combustion process and emissions by monitoring concentration and temperature fields;
- develop a mathematical model which describes the effects of BioLime injection on SOx/NOx emissions and predicts the optimal operating parameters.
Technical approach Recently, organic calcium salts like calcium acetate, calcium magnesium acetate and calcium benzoate have been shown to simultaneously reduce SOx and NOx emissions at elevated temperatures, typical of coal and heavy fuel oil combustors, at considerably lower Ca/S ratio's than in the current practice of in-situ desulphurization (1.1:1 instead of 3:1). Biomass pyrolysis liquors offer a low cost feedstock for the preparation of such organic calcium salts. Bio-oil can easily be obtained by rapid heating of any kind of biomass in absence of oxygen, whereby subsequent condensation of the product vapours yields 70 wt% bio-oil. This bio-oil is then modified by adding lime Ca(OH)2 to yield the sorbent " BioLime" which contains the organically bonded calcium. The clue is that the combustion of calcium enriched bio-oil yields finely dispersed, micro-scale sized CaO which is highly reactive towards SOx and capable of capturing more than 90% of the SOx emission, while being converted completely to harmless gypsum, at the reduced costs of US.
Funding SchemeCSC - Cost-sharing contracts
MK40 3PQ Bedford