Study On The Influence Of Typical Syngas Component On Molten Salts Desulfurization Performance And Molten Salts Regeneration Process

H₂S and COS are the sulfur-containing pollutants with the highest content in the gaseous products（syngas）of coal gasification or the pyrolysis of waste tires and biomass.On the one hand,when syngas is used in high-efficiency combination technologies such as integrated gas combined cycle power generation（IGCC）,sulfur-containing gas can cause the corrosion of equipment and pipelines or poisoning of catalysts.On the other hand,the traditional wet desulfurization technology needs to repeatedly raise and lower the temperature of the synthesis gas,which will result in the loss of heat.Therefore,medium and high temperature desulfurization has become one of the key technologies to improve the overall operating efficiency of the high-temperature combined technology.As a high temperature melt with good reactivity and fluidity,molten salts provide a novel technology for medium to high temperature desulfurization.However,the complex gas components in the actual pyrolysis/gasification gas might have negative influences on the desulfurization performance of molten salts.This paper investigated the influence of typical gas components on the desulfurization effect of ternary molten carbonates.And the main factors affecting the regeneration of sulfur-containing molten salts was tested through experiments.Based on the typical components of syngas,the main gas components that affect the desulfurization effect of molten salts were clarified through chemical equilibrium calculation.Besides,the influence of four typical gas compositions（H₂/CO/H₂O/CO₂）on the desulfurization effect of molten salts was emphatically studied.The influence of different atmospheres on the desulfurization effect of molten salts is clarified.The main process mechanism of molten salts desulfurization and the desulfurization enhancing path of calcium carbonate addition of the molten salts were described.Moreover,the effects of temperature,H₂O,and gas flow rate on the regeneration effect of sulfur-containing molten salts were also explored.The main factors affecting the regeneration rate and regeneration effect of sulfur-containing molten salts are figured out.Specific contents are as follows:（1）In H₂/CO atmosphere,500 ℃ molten salts could maintain excellent desulfurization effect,and more than 90%of sulfur-containing gas could be removed.The form of sulfur-containing gas will not change significantly under the influence of H₂/CO.The introduction of H₂O/CO₂would obviously inhibit the absorption of H₂S/COS by molten salts,and the desulfurization efficiency of molten salts after 10hours of reaction was less than 75%.In addition,the reaction of H₂O and COS would be obviously promoted by molten salts.A large amount of COS was converted into H₂S.The conversion process was as follows:H₂S first reacted with COS and molten salts to form metal sulfide.Then,the metal sulfide was dissolved in molten carbonates and S^2-ions was released.Finally,when there was a large amount of H₂O,the S^2-ions in the molten salts combined with H₂O to generate H₂S,while CO₂was converted to CO₃^2-.（2）The addition of calcium carbonate improved the removal effect of molten salts on sulfur-containing gas.In H₂/CO atmosphere,molten salts containing calcium carbonate could reduce 800 ppm H₂S/COS to less than 20 ppm.Besides,the addition of calcium carbonate significantly weakened the negative impact of H₂O/CO₂on the molten salts desulfurization process.The main process was:Ca CO₃dissolved into molten salts and released Ca²⁺.Ca²⁺reacted with S^2-ions to form CaS precipitation,which reduced the contact of S^2-ions with H₂O and CO₂.Finally,the desulfurization effect of molten salts was improved.（3）The regeneration effect of sulfur-containing molten salts was greatly affected by temperature.At 500 ℃,only less than 50%of the sulfur-containing components were regenerated and separated from the molten salts.However,at 425 ℃ more than 90%of the Na₂S in the molten salts was regenerated into carbonate when15%H₂O and 15%CO₂was introduced.In addition,the increase in the amount of H₂O addition and the gas flow would increase the regeneration rate of the sulfur-containing molten salts,but has little effect on the overall regeneration rate of the molten salts.