| The mass flow rate of recycled flue gas dust, electrostatic precipitator dust and ash hopper dust, in kraft recovery boilers was quantified. The fluctuation of the recycled dust mass flow rate during normal operation of the boiler was evaluated. The effects of four modifications in boiler operating parameters on the recycled dust flow rate were determined.; The results show that the recycle dust varies between 3.6 and 9.8% of the as-fired black liquor solids. Following a five-hour shutdown of economizer sootblowers, approximately 10,000 kg of ash hopper dust was added to the black liquor over the one hour test period upon the start-up of the economizer sootblowers at mill 'A'. Analysis of the samples collected in both mills confirmed the enrichment of chloride and potassium in the recycled dust.; Based on two mill surveys, it was confirmed that the recycled dust mass flow rate fluctuates with normal operation of the recovery boiler. It is suggested that these fluctuations be considered in the design of the chloride and potassium removal system. |
