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Ireland (coal/oil)

Site name: Kilroot

Town: Carrickfergus
Country: Northern Ireland
Client: AES Corporation
MWe: 520MWe (oil) / 440MWe (coal)
Fuels: coal and heavy oil
Year: 2004  Part 1 of project completed
Year: 2008  Part 2 of project completed

 Nature of project

A turnkey project run under CDM regulations to engineer, model, supply, start-up and optimise unique RJM combustion enhancements for boilers 1 and 4 initially to reduce NOx emissions in line with current LCPD regulations. CiA emissions must also be controlled to within saleable limits for the flyash.

Background

Parameters: 930 t/hr, 16.9 MPa, 540°C SH, 540°C RH
Boiler Type: International Combustion Tangential Fired Unit
Existing Combustion System: LNCFS (Low NOx Concentric Firing System)
Existing baseline: NOx <650mg/Nm3 @ 6% O2 when coal firing; <450mg/Nm3 @ 3% O2 when firing heavy oil.

Objectives

To reduce NOx emissions to the new LCPD threshold of 500mg/Nm@ 6% O2 for coal-firing and 400mg/Nm@ 3% O2 for oil-firing. The project guarantee had to ensure that AES could maintain compliance with its PPA (Power Purchase Agreement) with Northern Ireland Electricity. In addition, the reduced NOx emissions had to be achieved in such a way that a) CO emissions were not adversely affected, b) that excess Owould not increase significantly as this affects boiler efficiency and c) that CiA (Carbon in Ash) would not rise beyond the saleable limit of 7% CiA. In addition the hardware modifications needed to be made during a relatively short outage period and the untis needed to return to service ready to generate reliably.

Final results

RJM performance data confirmed a 31% reduction in NOx firing South African coal, a 47% reduction in NOx firing Colombian coal and a 22% reduction in NOx firing oil. CiA was reduced by 31% firing South African coal and by 69% firing Colombian coal. "We were very pleased with the RJM design process and the end results have exceeded expectations," commented Lyle Woodward, AES Project Manager for AES.

CFD optimisation of OFA system to control CIA and CFD model comparison of baseline NOx (LHS) to RJM upgrade NOx (RHS)