Study On K₂CO₃ Failure Mechanism Of CO₂ Adsorption In Simulated Flue Gas

CO₂ emission reduction technology is currently one of the research hotspots in the international community.Among them,potassium-based adsorbent decarburization technology had drawn extensive attention due to many advantages such as high removal efficiency,no secondary pollution,low cost and high recycling efficiency.At present,the potassium-based adsorbent decarburization technology had carried out the carbonation reaction characteristics,the regeneration reaction characteristics and the carbonation performance of the adsorbent supported on various carriers.There are some fly ash particles and a small amount of acid gas in the flue gas.Therefore,it is necessary to explore the characteristics of K₂CO₃ for removing CO₂ and the effect of K₂CO₃ on the failure of adsorbent in the simulated flu gas.Based on the previous research results,the carbonation reaction and regenerative reaction experiments were carried out in a self-designed small fixed bed and tubular furnace to explore the effects?including fly ash,NO,SO₂ and HCl?on the carbonation reaction characteristics,regeneration characteristics and the failure of adsorbents under different concentrations and reaction temperatures.The composition and element content after the carbonation reaction and regenerative reaction were characterized by XRD,XRF and XPS.With the heip of BET and SEM,the surface morphology and microstructure of the agent before and after the reaction parameters were sudied.Therefore the mechanism of different substances on the failure of adsorbent was explored.There was no obvious chemical change in the process of carbonation and regenerative reaction of the fly ash in pulverized coal boilers.Carbonation conversion increased mainly by its physical adsorption.During the carbonation reaction,the fly ash from pulverized coal boiler would not affect the adsorption continues after the adsorption saturation.With the proportion of fly ash increasing,the amount of CO₂ adsorption increased.The regeneration process could completely regenerated CO₂.After ten cycles,the decay rates of the adsorbent were 10.9%because the fly ash particles attached to the active site of the adsorbent to reduce the degree of carbonation.In the experiment,it was also found that the fly ash under different loadings had the same effect on CO₂ adsorption by K₂CO₃.There were no new substances in the process of carbonation and regenerative reaction of fly ash of circulating fluidized bed boilers.The fly ash would prevent the diffusion of CO₂ to reduce gas contact with the active ingredient after adsorbent saturation.With the increasing of fly ash ratio of CFB,the adsorption capacity of CO₂ decreased.After ten cycles,the decay rates of adsorbents were 8.05%.The failure was mainly due to the fact that fly ash particles were attached to the surface of adsorbent to prevent the positive reaction between CO₂ and adsorbent.In the process of carbonation and regenerative reaction,NO didn't generate nitrogen oxides to invalidate the adsorbent.After ten cycles,the decarburization rate of the adsorbent was not attenuated and still had high activity.SO₂ competed with CO₂ in the carbonation process for adsorption and reacted with K₂CO₃ to form K₂SO₃ which was not regenerated.After ten cycles,the sorbent failure rate _ul 26.02%.HCl gas would inhibit the reaction of K₂CO₃ and CO₂ during the carbonation reaction,and it reacted with K₂CO₃ to form KCl which still existed after regeneration.After ten cycles,the sorbent failure rate _th 7.94%.Decarburization-regeneration experiments were carried out in a simulated flue gas atmosphere with fly ash and three acidic gases.The results showed that K₂SO₄ and KCl impurities were formed after a single cycle which were not renewable,but they didn't affect the complete regeneration reaction of the active components.Adsorbent completely failed after fourteen cycles.Among them,Si O₂ was stable during the reaction.SO₂ reacted with K₂CO₃ to form K₂SO₃ and K₂SO₄ during the reaction,resulting in a sorbent failure rate of3.2%-7.34%.In the reaction process,HCl reacted to produce KCl,which caused the failure rate of adsorbents to be 82.08%-84%.The total failure rates of the adsorbents after the carbonated and regenerated through the fourteenth cycles were sepatately 87.2%and 89.42%.