The Effect Of Alkaline Minerals And Sulfur On Combustion Ash Of Biomass And Coal

Biomass and coal combustion is a promising way of energy utilization, the existence and migration of alkali metal in the fuel is the immediate cause to slag and foul. Sulfur dioxide that generated during the burning course of sulfur will bring about environmental pollution. When the alkali metal and sulfur react, alkali metal sulphide is produced. The alkali metal is also immobilized in the ash, which reduce the migration of alkali metal and bring down slagging and fouling. This paper researches the ash characteristics from the formation rate, components, melting point and subatomic shape of ash to know the effects of biomass and coal co-burning by the reaction of alkali metal and sulfur.First, the impact of alkaline mineral on the rate of producing ash in combined combustion of coal and biomass is analyzed. The results show that sulfur content on the rate of producing ash in combustion of pure coal has little effect, and the rate of producing ash of pure coal in combustion is in the range of 5%. But sulfur content on the rate of producing ash in combustion of mixture has great effect relatively. When S/K molar ratio is 3, the impact of sulfur content on the rate of producing ash in combustion of pure biomass is the greatest. At the moment the rate of producing ash increase by about 15% than the original biomass.Follow by analyzed the ash component effect by alkali metal and sulfur reacting to each other, the results indicates, when moral ratio of S/Ca increases, the content of potassium arrive maximum, the content potassium is about 30% while moral ratio of S/Ca is between 1 and 2.Analyze the ash-fusion temperature, structures and morphologies by ash melting point, XRD and SEM. The result indicates that the melting point of coal increases slightly with a rise and decrease in the content of sulfur. The content of sulfur has a notable impact on mixture's ash melting point, the increase of characteristic temperatures range from 100K to 300k. The moral ratio of S/Ca between 1/3 and 2, the ash melting point increases gradually. With the moral ratio more than 2, the ash melting point decreases gradually.At last, the effect to ash fusibility of alkali metal and sulfur analyzed by gray association degree theory. The results show that correlation degree of silicon dioxide is the biggest and silicon is the most important element to ash fusibility.