WinGD and Wärtsilä Gas Systems have tested a NG-VOC (Natural Gas – Volatile Organic Compounds) fuel mix for the WinGD X-DF engine, which will be used to power AET’s two 125,000 DWT shuttle tankers.
The tests, undertaken at Wärtsilä’s test facility in Trieste, Italy, demonstrated the engine’s capabilities under various load scenarios with up to 20% VOC in the fuel ratio. The engine is said to have sustained high performance throughout transfers from pure NG to a VOC mix, as well as transferring to diesel mode and back again. NOx emissions were reported to have remained significantly below IMO Tier III levels while operating on the NG- VOC mix.
Marcel Ott, Senior Project Manager DF Technology, Research & Development at WinGD, commented on the test results: ‘An early finding on the first X-DF engines with low-pressure gas admission to enter service was that their inherently stable combustion gave scope to run the engines on gas with lower methane numbers. Working with our partners from Wärtsilä Gas Systems from Norway and the local team at the Wärtsilä test facility in Trieste, we have applied this knowledge to the new fuel combination.’
Wärtsilä notes that to burn the NG-VOC mix, the X-DF engine concept remains unchanged.
Ott explained: ‘There are no significant changes in performance and emissions behaviour – the engines are fully IMO Tier III compliant burning the natural gas-VOC mix. In fact, aside from a few precautions according to ambient and boundary conditions, no hardware modifications and no application-specific control functions are required on the engine, and standard tuning can be retained. Likewise, the gas handling safety philosophy is identical with X-DF dual-fuel engines burning natural gas solely.'