RACECOURSE COGENERATION PROJECT

IN JANUARY 2010, approval was granted for the construction of a $120m 38 MW cogeneration plant at Racecourse Mill. The project was completed within budget and commissioned by February 2013 in line with the project timeline. The power plant comprises an Austrian Energy and Environment (AE&E) designed 80 bar 525°C steam boiler feeding high pressure steam to a 38 MW pass-out/condensing Shin Nippon turbine generator. Steam is passed from the turbine at two intermediate pressures to provide melter steam to the refinery via a steam transformer, and to operate a mill pre-evaporator which boils ESJ during the crush and refinery return condensate during the non-crush. Approximately 45% of the turbine inlet steam passes through to the vacuum condenser, although this flow varies with factory and refinery process steam requirements to provide constant boiler loads. Other than a two-week shutdown coinciding with the annual refinery maintenance period, the cogeneration plant operates year-round and is designed to export over 25 MW continuously into the Mackay network, equal to 30% of Mackay’s electricity demand. During the first 13 weeks of the non-crush, the plant will be fuelled by 130 000 tonne stored bagasse transported from Marian and Farleigh Mills. The project included a new 45 000 tonne capacity bagasse storage pad at Marian to supplement the existing 90 000 tonne pad at Racecourse. The bottom-supported boiler has a moving grate and is designed to operate on coal for the balance of the non-crush, when electricity exports will be reduced during off-peak price periods. The project was managed by Mackay Sugar who took over the Power Plant EPC contract when AE&E went into receivership. 143 contracts were awarded during the three-year construction period and over 400 000 site man-hours were worked with one recorded lost time injury. Balance of plant contracts included an old boiler demolition, new switchroom and control room, water polishing plant and evaporator and heater station modifications, while Ergon Energy constructed a new substation and 5.5 km of new 66 kV powerlines to connect to the local grid.