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Carbon capture at moderate pressures and temperatures
• Moderate pressures around 15 bar
• Moderate temperatures– Hydrate formation at 2-6 oC
• Not far below cooling water temperatures in Nordic countries
– CO2 release 20 – 40 oC• Typical waste heat temperatures
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Main concept overview
A closed process involving cooling, heating, compression and decompression stages to form and melt CO2 hydrates
Flue gas
99% CO2 1% N2
N2Traces of CO2
15% CO285% N2
Hydrate promoter (formation pressure)
Seed particles (reaction kinetics)
Electric powerCooling waterWaste heat
The separation is possiblesince CO2 forms hydrates more easily than N2.
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The problem with hydrate processes
• There is usually a long induction time before hydrate production start– Seed must form and grow to a certain size before detectable gas
absorption is observed – This takes a long time – hours and days in pure systems
• The hydrate forms first where the gas concentration is high– Thus a droplet gets a hydrate crust around a wet inside
• This hinders the transport of gas into the water phase• And heat away from the reaction centre
• Speeding up the process – the IFE contribution and a possible breakthrough– Using heterogeneous seed particle to speed up hydrate
formation – induction time reduced by a factor of 200
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Comparing to chilled ammonia process
• From literature chilled ammonia process consumes energy in the range:– 470 – 550 kWh/ton CO2
• A first rough estimate for a hydrate process:– 220 – 330 kW/ton CO2 (0.8 – 1.2 GJ)