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Progress in Ca-based CO 2 capture research at Cranfield University

Progress in Ca-based CO 2 capture research at Cranfield University. Ondřej Mašek , Adina Bosoaga, John Oakey. Outline of our activities. 1) flash calcination of limestone 2) entrained flow carbonation 3) entrained flow CO 2 capture in a pilot-scale combustion facility

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Progress in Ca-based CO 2 capture research at Cranfield University

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  1. Progress in Ca-based CO2 capture research at Cranfield University Ondřej Mašek, Adina Bosoaga, John Oakey

  2. Outline of our activities 1) flash calcination of limestone 2) entrained flow carbonation 3) entrained flow CO2 capture in a pilot-scale combustion facility 4) effects of operating pressure and contaminantson performance of Ca-based sorbents 5) Calcium looping

  3. 1) Flash calcination OBJECTIVES: • effects of temperature on flash calcination • effects of sorbent particle size • effects of CO2 partial pressure

  4. Flash calcination CH4 CaCO3 O2/Ar +CO2 O2/Ar Solids, gas mixture Nozzle Operating parameters • limestone with 95.5 % CaCO3 • feeding rate 10 g min-1 • temperature: 750 – 1000 °C • <100, 300-350 and 500-600 mm • CaO/CO2 : 0.06 – 0.37 Calcination zone, ~ 0.5 m length N2 Cyclone Cooling zone solids collection

  5. Flash calcination Effects of temperature and particle size on calcination efficiency • at 850 °C larger particles do not decompose • flash calcination efficiency reached over 90 % for fine particles

  6. Flash calcination Effect of CO2 partial pressure on calcination efficiency of <100 mm fraction CO2 partial pressure • decreasing CO2 partial pressure lowers the calcination temperature • with increasing temperature, the effect of CO2 partial pressure decreases

  7. Flash calcination Effect of CO2 partial pressure on calcination efficiency of 500-600 mm fraction CO2 partial pressure • decreasing CO2 partial pressure lowers the calcination temperature • with increasing temperature, the effect of CO2 partial pressure decreases

  8. Flash calcination a b fresh limestone <100 mm calcined limestone <100 mm - Insignificant sintering under the conditions employed

  9. 2) Entrained flow carbonation OBJECTIVES: • effects of temperature on entrained flow carbonation • effects of particle residence time on conversion • effects of CaO/CO2 ratio

  10. Entrained flow carbonation rotameter Operating parameters needle filter particle feeding system • starting material: natural limestone (99.95 % CaCO3) • calcination in an oven (30 min. at 850 °C) • mean particle diameter: 60 mm • particle residence time :1-3 s • temperature: 550 – 670 °C • CaO/CO2 ratio: 0.85-2.15 CO2 inlet to CO2 analyser vent air inlet filters cooling coil rotameter reaction zone fluidised bath

  11. Entrained flow carbonation

  12. Entrained flow carbonation CaCO3 CaCO3 CaO CaO SEM image of the solids carbonated at 587 ° C with residence time of 2.59 s.

  13. 3) CO2 capture in pilot scale combustion facility OBJECTIVES: • lime performance in a real combustion atmosphere • effects of temperature on carbonation

  14. CO2 capture in pilot scale combustion facility Total combined thermal output of 150 kW Lime injection Optional PC burner Screw feeder Material testing zone Carbonator Heat exchanger FBC Cyclone The FBC Nat. gas preheater The Carbonator Particle removal system

  15. CO2 capture in pilot scale combustion facility Operating parameters - commercial lime with 96% CaO (< 75 mm) - feeding at 3.6 kg/h (limited by the feeding system) - residence time within the carbonator was about 2 s

  16. CO2 capture in pilot scale combustion facility Results

  17. 4) Effects of op. pressure and contaminants on performance of Ca-based sorbents OBJECTIVES: • effects of operating pressure • effects of steam • effects of SO2 partial pressure • effects of CO2 partial pressure

  18. Effects of op. pressure and contaminants on performance of Ca-based sorbents flue gas sample feed pressure vessel Operating parameters • - operating pressure: 0.1 – 1.5MPa. • operating temperature: 950 °C • SO2 partial pressure: 250 – 5000 ppmv el. furnace gas inlet

  19. 5) Calcium looping OBJECTIVES: • transport of solids between carbonator and calciner • effects of steam • effects of SO2 partial pressure • effects of CO2 partial pressure • cycle optimisation

  20. flue gas Flue gas cyclone loop seal 650 °C CO2 rich flue gas CALCINER 950 °C CARBONATOR gas burner solids extraction loop seal Calcium looping • CALCINER • bubbling fluidised bed • temperature 950 °C • CH4/O2 burner • CARBONATOR • entrained flow reactor • temperature 650 °C • CH4/air burner

  21. THANK YOU ! Ondřej Mašek o.masek@cranfield.ac.uk

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