Study On Combined Removal Of CO₂,SO₂ And NO Based On Calcium-based Sorbents

Emission control of coal-fired power plants for SO2 and NOx is increasingly stringent.It is of great significance to study the low-cost joint removal of new technologies.This paper proposes a new idea for the combined removal of CO2,SO2 and NO based on calcium-based sorbents and prepares a synthetic sorbent with high CO2 capture performance.This paper uses CaO/biomass to efficiently removal SO2 and NO in flue gas,which is expected to significantly reduce operating costs and achieve ultra-low emissions of SO2 and NO.A novel synthetic sorbent is fabricated from CaO and sepiolite by the hydration and its CO2 capture performance is investigated during the calcium looping cycles.The effects of the sorbent preparation conditions including preparation method,hydration temperature,hydration duration and sepiolite content on CO2 capture by synthetic CaO/sepiolite sorbent are examined in a dual fixed-bed reactor.Under optimum preparation conditions,the CO2 capture capacity of the synthetic CaO/sepiolite sorbent after 10 cycles is 56%higher than that of CaO.The synthetic CaO/sepiolite sorbent exhibits higher cyclic CO2 capture capacity due to the formation of MgO and Ca2SiO4 as good supports by the reaction between sepiolite and Ca(OH)2,which enhances the sintering resistance during the cycles.The synthetic CaO/sepiolite sorbent has a well-developed pore structure,a large specific surface area,and a specific pore volume.The volume of pores in the range of 10-100 nm in diameter of CaO/sepiolite after the 1st calcination is 1.3 and 7.5 times as large as those of hydrated CaO and original CaO,respectively,which is beneficial for CO2 capture.This paper studies the performance of CaO/biomass--coconut shell coke simultaneous removal SO2/NO in bubbling fluidized bed reactor system,and the coke type,CaO and coconut shell coke particle size,suitable CaO/coconut coke mass ratio,reaction temperature,and fluidization number are determined experimentally.Under optimal conditions,the efficiency of NO removal from CaO and coconut coke is as high as 98%,and SO2 removal efficiency is close to 100%.It is found that CaO can significantly promote the reduction of NO by coconut shell coke.Compared with the original CaO,using CaO after 5 fluidized carbonation/calcined cycles and coconut shell coke removal SO2/NO slightly lower,but the SO2 and NO removal efficiency can still reach 98.6%and 96%respectively.In order to solve the effect of complex temperature conditions in the furnace,under non-isothermal fluidization conditions,the experiment studies the effects of O2 and CO2 on the simultaneous removal SO2/NO from CaO/biomass,and the interaction between SO2 and NO.It is found that O2 can strongly promote CaO/biomass to simultaneous removal SO2/NO in flue gas.CO2 can inhibit CaO/biomass to simultaneous removal SO2/NO in flue gas.However,in the presence of both O2 and CO2,the promoting effect of O2 on CaO/biomass to simultaneous removal SO2/NO is greater than that of CO2.