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The mix of gas and VOC was tested on WinGD’s RT-Flex 50DF dual-fuel demonstrator engine in Trieste

WinGD and Wärtsilä Gas Systems have tested a mix of natural gas and volatile organic compounds (VOC) in WinGD’s dual-fuel demonstrator engine in Trieste.

The test – witnessed by AET, Statoil, OSM Maritime Group, Samsung Heavy Industries and Hyundai Heavy Industries – demonstrated the engine’s capabilities under various load scenarios with up to 20% VOC in the fuel mix. The engine maintained performance throughout transfers from pure natural gas (NG) to a VOC mix, as well as transferring to diesel mode and back again. The test confirmed that NOx emissions remained well below IMO Tier III levels while operating on the VOC mix.

The capability has already been specified by AET for a pair of shuttle tankers and could hold considerable attraction for the oil and gas industry. VOCs are a waste product from crude oil handling and transport, representing both a hazard and a loss of revenue to oil and gas producers and shippers. Historically, they were either discharged into the atmosphere or burned off.

Marcel Ott, senior project manager, dual-fuel technology, research and development, WinGD, said: “An early finding on the first X-DF engines was that their inherently stable combustion gave scope to run the engines on gas with lower methane numbers. We have applied this knowledge to the new fuel combination.”

Ott noted that no significant changes in performance or behaviour is required for X-DF engines to burn the NG-VOC fuel mix. “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,” he said.

The project also established that the X-DF engines’ low-pressure gas admission helps to mix VOC into the natural gas fuel, as condensation of the heavy hydrocarbons in the VOC can be avoided.

Dominik Schneiter, vice president, research and development, WinGD, said: “Our X-DF engines now offer ship owners a further way to improve their environmental footprint while reducing fuel cost. The NG-VOC capability will add a further dimension to the benefits that make our X-DF engines such a strong contender for ship owners facing tighter emissions controls and increased operating costs.”