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 4) effects of operating pressure and contaminants on performance of Ca-based sorbents 5) Calcium looping

1) Flash calcination - effects of temperature on flash calcination - effects of sorbent particle size - effects of CO 2 partial pressure OBJECTIVES:

Flash calcination CH 4 N2N2 CaCO 3 Nozzle Solids, gas mixture Calcination zone, ~ 0.5 m length Cooling zone Cyclone O 2 /Ar O 2 /Ar +CO 2 - limestone with 95.5 % CaCO 3 - feeding rate 10 g min -1 - temperature: 750 – 1000 °C - <100, and  m - CaO/CO 2 : 0.06 – 0.37 solids collection Operating parameters

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

Flash calcination - decreasing CO 2 partial pressure lowers the calcination temperature - with increasing temperature, the effect of CO 2 partial pressure decreases CO 2 partial pressure Effect of CO 2 partial pressure on calcination efficiency of <100  m fraction

Effect of CO 2 partial pressure on calcination efficiency of  m fraction CO 2 partial pressure Flash calcination - decreasing CO 2 partial pressure lowers the calcination temperature - with increasing temperature, the effect of CO 2 partial pressure decreases

Flash calcination a b fresh limestone <100  mcalcined limestone <100  m - Insignificant sintering under the conditions employed

2) Entrained flow carbonation - effects of temperature on entrained flow carbonation - effects of particle residence time on conversion - effects of CaO/CO 2 ratio OBJECTIVES:

Entrained flow carbonation reaction zone particle feeding system air inlet rotameter needle CO 2 inlet to CO 2 analyser fluidised bath rotameter filters vent cooling coil filter Operating parameters - starting material: natural limestone (99.95 % CaCO 3 ) - calcination in an oven (30 min. at 850 °C) - mean particle diameter: 60  m - particle residence time :1-3 s - temperature: 550 – 670 °C - CaO/CO 2 ratio:

Entrained flow carbonation

CaCO 3 CaO CaCO 3 CaO SEM image of the solids carbonated at 587 ° C with residence time of 2.59 s.

3) CO 2 capture in pilot scale combustion facility - lime performance in a real combustion atmosphere - effects of temperature on carbonation OBJECTIVES:

Nat. gas preheater CO 2 capture in pilot scale combustion facility The FBC Screw feeder Optional PC burner Material testing zone Heat exchanger Cyclone Lime injection FBC Particle removal system Total combined thermal output of 150 kW The Carbonator Carbonator

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

CO 2 capture in pilot scale combustion facility Results

4) Effects of op. pressure and contaminants on performance of Ca-based sorbents - effects of operating pressure - effects of steam - effects of SO 2 partial pressure - effects of CO 2 partial pressure OBJECTIVES:

el. furnace sample feed flue gas pressure vessel - operating pressure: 0.1 – 1.5 MPa. - operating temperature: 950 °C - SO 2 partial pressure: 250 – 5000 ppmv gas inlet Operating parameters Effects of op. pressure and contaminants on performance of Ca-based sorbents

- transport of solids between carbonator and calciner - effects of steam - effects of SO 2 partial pressure - effects of CO 2 partial pressure - cycle optimisation OBJECTIVES: 5) Calcium looping

Flue gas gas burner CO 2 rich flue gas solids extraction cyclone loop seal CARBONATOR 650 °C CALCINER 950 °C flue gas Calcium looping CALCINER - bubbling fluidised bed - temperature 950 °C - CH 4 /O 2 burner CARBONATOR - entrained flow reactor - temperature 650 °C - CH 4 /air burner

THANK YOU ! Ondřej Mašek