Abstract:

With the increasing share of renewable energy in power system, more and more coal-fired power units participate flexibility generation. For clarifying the air emission characteristics of flexibility generation, the operation history data of two subcritical coal-fired power units (600 MW and 300 MW) are used for regression analysis. In normal cyclic operation, power ramping-down will lead to a little increase in coal consumption rate and CO₂ emissions factor. Meanwhile, the NO_x emissions factor will decrease firstly and then increase when ramping down and the amplitude of variation is little in clean flue gas. The SO₂ emissions factor will decrease a little while dust factor will increase a little when ramping down. In deep cycling operation, the increase in coal consumption rate and CO₂ emissions factor will be much larger, while the NO_x and dust emissions factors will increase substantially when SO₂ emissions factor continues to decrease in clean flue gas. In start-up process, the NO_x and dust emissions are much larger while SO₂ emissions are slightly smaller than regular operating conditions. In addition, larger ramping rate has remarkable impact on NO_x and SO₂ in untreated flue gas and on dust in clean flue gas in deep cycling conditions.

Key words: coal-fired power unit, flexibility generation, air emissions characteristics, regression analysis