研究不同机组负荷、还原剂制备方式下超低排放燃煤机组SO₃和NH₃生成及迁移规律,结果表明:负荷的升高促进SCR(选择性催化还原)系统内SO2转化为SO₃,也会促进氨逃逸上升;机组负荷的升高抑制SO₃和NH₃在空预器段迁移;3种还原剂制备方式的机组,SO₃迁移比例在空预器为1.5%～10.4%,在LLT-ESP(低低温电除尘器)为33.7%～53.9%,在FGD(脱硫塔)为17.0%～29.3%; NH₃在空预器和LLT-ESP的迁移比例分别为23%～50%和50%～67%,进入FGD量极少;还原剂制备方式短时对NH₃和SO₃生成及迁移影响不明显,长期运行可能造成氨逃逸上升,进而影响SO₃迁移。

In this paper, the formation and migration characteristics of SO₃ and NH₃ in ultra-low emission coal-fired units under different unit loads and reductant preparation methods are studied. The results show that load increase accelerates the conversion of SO2 to SO₃ in a selective catalytic reduction(SCR) system, and also increases the escaped ammonia. The increase of unit load inhibits the migration of SO₃ and NH₃ in the air preheater. The migration ratios of SO₃ in air pre-heater, LLT-ESP(low-low temperature electrostatic precipitator), and FGD(flue gas desulfurization) of different reductant preparation methods units are respectively 1.5%～10.4%, 33.7%～53.9%, and 17.0%～29.3% of the total SO₃. The migration ratios of NH₃ in air pre-heater and LLT-ESP of different reducing agent preparation methods units are 23% ～50% and 50% ～67% respectively with a small amount of NH₃ entering FGD. The preparation method of the reductant has no obvious impact on the generation and migration of NH₃ and SO₃ in a short time, but its long-term operation may cause ammonia escape increase, which in turn affects the SO₃ migration.