DE-VOC System

VOC Reduction System for Crude Oil Loading Operations

Cutaway 3D model of a crude oil tanker cargo tank fitted with DE-VOC anti-cavitation valves — Anti-cavitation valves arranged in the cargo tank (3D model from the company profile).

During crude oil loading, the pressure at the top of the cargo drop line is often lower than ambient pressure because of the vertical height of the line. When this pressure falls below the True Vapor Pressure (TVP) of the crude oil, vaporization occurs and Volatile Organic Compounds (VOC) are generated.

As the flow enters the tank bottom, part of the VOC is re-condensed through pressure recovery. Because the flow is not in thermal equilibrium, however, complete re-condensation is not possible, and the uncondensed VOC is released into the atmosphere. The result is both an environmental impact and a loss of cargo.

The DE-VOC system reduces that release by optimizing pressure recovery and condensation efficiency throughout the loading process. The system is installed in the cargo tank.

Technology and Scope

The DE-VOC technology is based on a patent held by Daewoo Shipbuilding & Marine Engineering (DSME, now Hanwha Ocean). JangWon SM Co., Ltd. took part in the joint development of the system over five years, and DSME granted JangWon SM the right to use the patented technology.

Internals of the DE-VOC anti-cavitation valve — Internals of the anti-cavitation valve, the core hardware of the DE-VOC system.

Our scope on the projects below covered:

System design and engineering
Procurement and manufacture of system components
Installation supervision at the building yard
Commissioning, onboard verification testing and reporting

Reference Projects

The DE-VOC system has been applied to 10 tankers in three stages, from a full-scale onboard demonstration to series application on VLCCs and Suezmax crude oil tankers.

No.	Owner	Vessels	Builder	Period	Class / Status
1	Bergesen Worldwide (BW Shipping)	1 crude oil tanker — “BW NYSA” (DSME H5123)	DSME	2009–2013	Full-scale onboard demonstration. System completed March 2011
2	Kuwait Oil Tanker Company (KOTC)	4 × 317,000 DWT VLCC (DSME H5389–H5392) 1 × 110,000 DWT Aframax product carrier (DSME H5393)	DSME	Installation Jan 2013 – Oct 2014 Onboard verification test Aug 2014 – Apr 2015	Delivered October 2014 — the first application of a cargo tank VOC reduction system to VLCCs
3	Ibaizabal Group (Spain)	4 × 156,000 DWT Suezmax crude oil tankers (PE 0540–PE 0543)	Navantia (Spain), EPC provider DSEC	Oct 2015 – May 2019	Installed on all four vessels

Verification and Certification Record

Onboard verification test, August 2014 – April 2015 — carried out on the KOTC vessels after installation.
Lloyd’s Register, June 2016 – April 2017 — testing for the additional class notation “VOC-R” on two of the 156,000 DWT crude oil tankers at Navantia.
ABS, July – December 2017 — Statement of Compliance for the DE-VOC system.

Presentations and Publication

October 2011 — principle of the system presented at the ME ShipTech 2011 conference.
July 2012 — technical presentation at the KOTC head office.
October 2013 — application cases presented at the ME ShipTech 2013 conference.
September 2015 — the system was featured in Lloyd’s List.
November 2015 — introduced to Greek owners and the shipping community.

For system drawings, test results or a retrofit study on a specific hull, please contact us.

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