Wärtsilä VOC recovery system

Our field proven system is self supplied with energy and results in zero volatile organic compounds (VOC) emissions.

These emissions from the global sea transportation of crude oil and associated products, account for a total of more than 5 million tonnes per year. The Wärtsilä VOC plant ensures that cargo tank pressures are maintained low enough to keep the vent valve closed. This prevents VOC from being emitted to the atmosphere, and the gas is instead fed to the VOC recovery module, where it is treated by compression and condensation. The liquefied gas is then fed to the VOC fuel tank.

We have also developed a system for VOC recovery in offshore oil loading applications. It exceeds the Norwegian authorities’ requirements for Non-Methane Volatile Organic Compounds (NMVOCs) by reducing VOC emissions by 100 per cent, including methane, which is not currently specified in the regulatory requirements.

    Technical data

    The recovery of VOC is accomplished by introducing tank vent gas into the VOC recovery system, and then using a condensation process to separate the heavier hydrocarbon fractions of the gas. The lighter hydrocarbon fractions are non-condensable and are fed to a power generating module, meaning that the VOC recovery is 100% and VOC emissions are entirely eliminated.

    The separated heavier fractions are liquefied from the VOC unit and stored in a pressurized storage tank. LVOC is a light hydrocarbon fuel that can be utilized as a clean fuel in power generating modules and inert gas generator units. The Wärtsilä VOC recovery system has been successfully utilized onboard several shuttle tankers and floating storage units (FSU) in the North Sea.

    Tanker Schematic

     In the offshore sector the VOC recovery system is most typically used onboard FSUs and shuttle tankers, where harmful VOC emissions are recovered instead of being emitted to the atmosphere.

    In addition to VOC recovery, Wärtsilä can offer different VOC utilization solutions where the recovered liquid VOC is used for power production. Wärtsilä’s patented GasReformer unit in combination with our dual-fuel engine technology, gives you the highest efficiency and flexibility. This solution provides environmental benefits with reduced VOC emissions, and economic benefits with fuel cost reductions of up to 40%.

    Key benefits

    The environmental impact of these emissions is significant as the emitted gas consists of a range of hydrocarbons from methane to higher (typically C6+). Methane is a greenhouse gas with a global warming potential (GWP) of 21 (GWP for CO2 is 1). The non-methane fractions, known as NMVOC, react in the presence of sunlight with nitrous oxides and create a toxic ground level ozone and smog layer, which has detrimental environmental effects on vegetation and on human health, particularly on the eyes and lungs.

    This is a design revolution

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