The new 51/60DF dual-fuel gas engine from MAN Diesel has passed its second major milestone in electrical power generation applications. Following closely on the handover of a heavy fuel engine retrofitted to full 51/60DF specification at an existing cogeneration installation in Portugal, MAN Diesel Australia has booked the first order for new engines in a power plant application.
The turnkey contract has a value of 60 million Australian dollars and covers the design and construction of a new 22 MW power station at Owen Springs, 25km south of Alice Springs, for Power and Water Corporation (PWC), a major Australian public utility. The Territory’s PWC is a Northern Territory government owned corporation. It currently operates 360 MW of power generation capacity and has more than 80 000 customers.
The new power station will be based on two 10.9 MWe generator sets, each powered by a twelve cylinder, vee configuration 12V 51/60DF engine. The generator sets will supply baseload power to the local grid in their gaseous fuel mode, ie burning natural gas ignited by a distillate fuel ‘micropilot’.
As well as the supply, installation and commissioning of the generator sets, the scope-of-supply comprises all engineering work including civil and structural works; supply and installation of all electrical equipment and the plant control and monitoring system; all auxiliary systems including cooling radiators and supplementary cooling towers to cope with the design ambient temperature of 40°C; project management; and the necessary logistical arrangements. Construction is due to start in the near future and completion of the first stage of the project is scheduled for April 2009, with final completion in 2010.
‘MAN Diesel Australia is an experienced company in power station construction and its parent company in Germany specialises in dual-fuel engines in the size range required for this project’ notes John Linton, PWC’s general manager for generation. ‘The contract specifications were technically complex as Power and Water was seeking world’s best practice in fuel efficiency and the lowest emissions of carbon dioxide per unit of electricity generated.’
For stationary power generation applications the 51/60DF is available in a nine cylinder inline version and in vee configuration versions with 12, 14, and 18 cylinders. The engines have mechanical ratings of 1000 kW per cylinder for 60 Hz power generation (514 rpm) and 975 kW for 50Hz applications (500 rpm). These give an overall generator-set rating range of 8560 to 17550 kWe.
With its fuel flexibility and low emissions, the 51/60DF targets applications where operation on a back-up fuel is either essential or desirable. The engine’s fuel flexibility centres on the capability to operate on either gaseous or liquid fuel, and to switch between them seamlessly at full rated output. In the gaseous fuel mode an air-gas mixture is ignited by injection of distillate diesel fuel. On the 51/60DF, the liquid fuel micropilot consumes 1% of the quantity of liquid fuel needed to achieve full rated output. It is injected via a common rail system which allows flexible setting of injection timing, duration and pressure for each cylinder. This flexibility allows the engine to achieve low emissions and to respond rapidly to combustion knock signals on a cylinder-by-cylinder basis.
In the back-up liquid fuel mode, the 51/60DF engine operates as a normal diesel engine injecting distillate or heavy fuel oil (HFO) through a separate, normally dimensioned injector in a camshaft actuated, pump-line-nozzle system.
At 500 mg /nm3 at 5% O2 on gaseous fuel, the 51/60DF achieves NOx emissions in compliance with both Germany’s TA Luft clean air regulations and the World Bank Pollution Prevention and Abatement Handbook.