MAN Diesel & Turbo recently showcased its new 35/44G four-stroke natural gas engine, designed for baseload, peaking and cogeneration plants. The newly developed Otto gas engine has an electrical efficiency of 47.2%, and is available for Combined Heat & Power (CHP) and/or jointly with a MAN steam turbine of the MARC series in a combined cycle mode reaching high total plant efficiencies with low emissions.
|The 20V35/44G engine on the MAN Diesel & Turbo test bed in Augsburg, Germany. Click to enlarge.
The 35/44G is offered in a V-type version with 20 cylinders and an output of 10,600 kWm for 50 Hz power generation, 10,200 kWm for 60 Hz generation). Its rated outputs—530 kW per cylinder and 510 kW—give the 35/44G best-in-class power density among gas engines.
The engine features a single-stage turbocharger with variable turbine area (VTA) technology. The spark-ignited lean-burn gas engine, which is suited for combined cycle and combined-heat and power configuration with waste-heat utilization, complies with all current emission limits solely by in-engine measures.
With leaner combustion, the peak temperature is reduced and less NOx is produced. Higher output can be reached while avoiding knocking and increasing efficiency.
The ignition system comprises a capacitive discharge system and an ignition coil, which delivers the necessary high voltage via an ignition lead to the spark plug. To improve combustion, the spark plug is located in the pre-chamber. Gas is precisely metered to the pre-chamber by means of a separate valve. In conjunction with the lean mixture from the main chamber, which is fed into the pre-chamber by the compression cycle, this creates a highly efficient, almost stoichiometric mixture. This is ignited using the spark plug, providing an ignition amplifier for the main chamber.
The 35/44G engine is equipped with the safety and control system SaCoSone, which enables reliable engine operation with an optimum operation range between knocking and misfiring. All cylinders are regulated individually.
In addition to using thermal energy recovered from engine sources for heating or cooling in cogeneration or tri-generation applications, the exhaust heat of the 35/44G engine can also be used to produce steam to drive a steam turbine generator. As a result, the overall output and efficiency of the power plant can be increased without additional fuel costs.