Comments re carbon usage in Poolbeg
The paper on Powdered Activated Carbon from Covanta is quite incomplete. The paper is undated,
unsigned and provides no references.
Only two figures are given – 20 kg / hour and 40 – 100 mg/Nm3 flue gas.
It is not clear if the 20 kg / hour refers to one line or to both lines.
The request from the SPC to Covanta via James Nolan was for the following:
Paper on how activated carbon is to be managed, monitored and controlled - especially the
planned dosage rate and how this will be monitored
At 47:30 into the webcast:
How much carbon does the industry recommend?
How much carbon are you going to use?
Why is there a difference?
The paper supplied gives no information on:
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the industry norms
the planned rate of usage for Poolbeg
an explanation for differences
dosage rate for commissioning
dosage rate for production
monitoring
reporting
During our visit to the plant last week we were told that residue from the bag filters is to be
recirculated to the reactor. No figures are given in the paper for the quantities to be recirculated.
The following questions arise:
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How much fresh powdered carbon will be injected per hour into each line?
How much residue will be recirculated per hour on each line?
What monitoring will be reported?
Who will assess and set the required dosage rate?
An explanation for the recirculation of carbon and lime is requested to understand the impacts on
dioxin removal efficiency of recirculated baghouse residue.
Given the crucial importance of powdered carbon injection to remove dioxins, a more complete
paper is requested with sourced recommendations for carbon management and monitoring in
Poolbeg before it is commissioned.
Joe McCarthy
An Taisce
5 April 2017