Abstract: Combining with the variation of coal actually fired in thermal power plant during last years, it is explained by example that when the coal quality varied, not only the variation of sulfur content must be considered, but also the influence of the low heat productivity of the coal on the mass concentration of SO2 must be taken into account. At last, some problems needing attention in operation while the parameters of flue gas diverge from the designed values were put forward.

Key words: desulphurization equipment, sulfur content of coal, heat productivity of coal, operation mode