磷矿与石灰双循环脱硫的工艺性能

采用磷矿、石灰2种脱硫剂在同一吸收塔中完成2次循环4次吸收的过程.吸收塔的下部为第1级循环,采用环栅式喷射鼓泡塔,以磷矿为脱硫剂,磷矿吸收SO2后加适量浓硫酸制成磷肥,以减少烟气脱硫除尘的运行成本.吸收塔上部为第2级循环,在传统的喷淋和浮阀板技术上进行了改进,以石灰为脱硫剂,以解决第1级循环中因磷矿所含脱硫成分少于石灰而导致的脱硫效率较低的问题,保证了较高脱硫效率.结果表明,塔的压降、脱硫剂的pH值是影响脱硫效率的关键因素,在第1级循环中磷矿浆液pH值在4.5～3.5时,脱硫效率趋于稳定;通过调整石灰水的pH值可使整个工艺脱硫效率达到80%.

Performance of a two-cycle flue gas desulphurization process using slurries of phosphorite and lime

Adesulphurization process for coal combustion was developed with two cycles and four stages of absorption in a tower using slurries of phosphorite and lime as individual absorbents. The lower part of the tower was an injecting-bubbling column where the phosphorite slurry was used as the absorbent. The phosphorite slurry which exits from the absorption cycle can be mixed with concentrated sulphuric acid to produce phosphate fertilizer, so the cost for the desulphurization and dust removal process can be reduced. The upper portion of the tower was an absorption tower combined with a conventional spray tower and valve tower, and lime slurry was used as absorbent to increase the desulphurization efficiency. The results showed that the important parameters which affected the desulphurization efficiency were pressure drop within the tower and the pHvalues of the absorbents. When the pHof the phosphorite slurry in the first circulation ranged from 3.5 to 4.5, the desulphurization efficiency remained stable. The desulphurization efficiency of the whole process reached a maximum of 80% through adjustment of the pHof the lime slurry.