Hydrothermal Reaction of Lime with Fly Ash to Prepare Ca-based Absorbent for Flue Gas Desulfurization
|Course||Chemical Process Equipment|
|Keywords||Ca-based absorbent Fly ash Optimization of preparing condition Kinetics of hydrothermal Reaction Additive|
In flue gas desulfurization, ordinary absorbent such as Ca(OH)2 or CaO had lower Ca-based utilization rate, which increased operating expense. Ca-based absorbent prepared by hydrothermal reaction of ordinary absorbent with fly ash had higher specific area, water retention capability & better activity to SO2. It could reduce operating expense rapidly.Optimization of preparing condition, application of additive, kinetics of hydrothermal reaction, properties of Ca-based absorbent & enlarged test were investigated for large-scale production.Firstly, the effects of hydrothermal factors on the specific area of Ca-based absorbent were studied. The preparing condition was optimized by using orthogonal test, union test & one-factor test. The specific area of Ca-based absorbent prepared in majorized condition is 90.256m2/g, seven times higher than Ca(OH)2.Secondly, grinding, sieving & adding chemical additive such as sulfate, alkali & soluble salt were investigated to improve the special area of the Ca-based absorbent. Enhancing the special area of fly ash & adding proper additive could increase the pozzolanic activity of fly ash & improve the special area of the Ca-based absorbent. Thirdly, a kinetic model was deduced about pozzolanic reaction for preparation of Ca-based absorbent on basis of solid phase reaction dynamic theory. The hydrothermal reaction was partited three stages. The kinetic characteristics and expressions in different condition were obtained.Fourthly, the characteristics of Ca-based absorbent were measured. The Ca-based utilization rate in majorized condition is 85.13%, three times higher than Ca(OH)2.Fifthly, preparing Ca-based absorbent in 200 times larger reactor for testing optimal conditions. The relative error in enlarged test could be satisfiable for large-scale production. Ca-based absorbent for flue gas desulfurization prepared in uncomplicated operation.