Limestone is first calcined at 850~950°C to obtain lime (CaO), which is very suitable for CO2 capture because of its high adsorption capacity (theoretical 786g CO2/kg). Next, CaO is reacted with the CO2 in the flue gas at 600~700°C to become CaCO3, and then the CaCO3 is transported to the calciner for CaO regeneration under high temperature, and finally the regenerated CaO can capture CO2 within the carbonator in the next cycle. This CO2 capture method, using CaO/CaCO3 being circulated in the system to adsorb/desorb CO2 in the flue gas, is called the Calcium-Looping process.
Applications & Benefits
- Design of cascade-cyclone can increase the mixing efficiency of limestone and hot stream, to increase the calcination efficiency to higher than 90%.
- Oxy-fuel combustion cyclone calciner with flue gas recirculation system can reduce energy consumption and produce CO2 with purity higher than 90%.
- Integration of steam hydration can increase CO2 capture efficiency and sorbent carbonation conversion in each carbonation/calcination cycle, which can reduce the sorbent consumption and recirculation rate to reduce the volume of the reactors and energy consumption.
- HECLOT can be applied in power generation, cement, steel, and petrochemical industries, while more than tens of millions of tons CO2 can be captured. The estimated investment cost and operating cost are more than hundreds of billions (NTD)and tens of billions(NTD), respectively.
- Since the economic and feasible scale is a 50MW demonstration plant, the commercial threshold can be considerably reduced. The demonstration plant can be integrated into a cogeneration power plant to promote the development of zero-emission process. The integrated process is expected to achieve a carbon capture cost of less than 30$/tCO2 and a power generation cost of less than 0.08 $/kWh.
High-efficiency Calcium Looping Technology (HECLOT) and its Applications