SINTEF 27/04/2015 CONTROL OF VOC EMISSION FROM CRUDE OIL TANKERS Otto M.Martens, MSc. Norwegian Marine Technology Research Institute (MARINTEK) Ole Oldervik, MSc. PhD. SINTEF Civil and Environmental Engineering Bengt Olav Neeraas, MSc. PhD. SINTEF Energy Research Terje Strøm, MSc. SINTEF Applied Chemistry

SINTEF 27/04/2015 Results from study on reduction of VOC emission from Crude oil tankers Focus on shuttle tankers and FSO/ FPSO Simulation of : –evaporation rates for individual volatile compounds –gas emission rates –composition of emitted gas Reduced emission by combination of control techniques: –sequential transfer of tank atmosphere (STTA) –reliquefaction of VOC –absorption of VOC in cargo oil

SINTEF 27/04/2015 INTRODUCTION The VOC emission represents: –a loss of considerable monetary value –harmful consequences to the environment National goal of 30 % NMVOC emission 50 % of emission in Norway from offshore loading Actions taken: –gas return and recovery plant at the Sture terminal –absorption plant on M/T “Anna Knutsen” –recondensation plant on M/T “Navion Viking” –several R&D projects and measurement series performed VOC diluted in inert gas creates a problem

SINTEF 27/04/2015 The VOCON RESEARCH PROJECT Sponsors -Statoil UBT/PRA -Saga Petroleum ASA -BP International Ltd -Shell Expro -Norsk Hydro -Kværner Ship Equipment -Aker Engineering, -Umoe Technology Sandsli -Bergesen DY AS -Navion -Norwegian Petroleum Directorate -Det Norske Veritas -Norwegian Council of Research -Norwegian Maritime Directorate -MARINTEK/SINTEF Performed by SINTEF Content : Emission measurements onboard Developed emission simulation program Evaluated concepts for VOC emission control –Required 75 % reduction of NMVOC emission

SINTEF 27/04/2015 The Simulation Program HCGas Typical components considered : –C1, C2, C3, i-C4, n-C4, i-C5, n-C5, C6, C7, C8, C9, C10+, N 2, CO 2, O 2 Transportation in liquid and gas phases by solving one dim diffusion/ convection equation for each component Local equilibrium at the free surface gives mass transfer of each component between the phases Mass continuity eq. for each tank and flow eq. for each pipe used to compute flow Loading and discharging rates specified Temperature specified in liquid phase as f(time, space) Temperature specified in gas phase as f(time, space) or computed

SINTEF 27/04/2015 Simulated cases m 3 cargo capacity all ships shuttle tanker and STL loaded and discharged from 3 similar tank groups in series average sea condition offshore fairly volatile crude shuttle tanker –loading rate 2.2 m 3 /s –discharge rate 2.7 m 3 /s

SINTEF 27/04/2015 SHUTTLE TANKER - BASE CASE

SINTEF 27/04/2015 SHUTTLE TANKER - BASE CASE

SINTEF 27/04/2015 SHUTTLE TANKER - STTA Emission of NMVOC: –base case kg –base case with STTA kg Compared to base case STTA gives: –reduced flow rate –reduced emission –reduced running time and better condition for recovery plant

SINTEF 27/04/2015 Shuttle Tanker with STTA and liquefaction plant

SINTEF 27/04/2015 Shuttle Tanker with STTA and absorption plant

SINTEF 27/04/2015 Gas Return from Shuttle Tanker to FSO with STTA on shuttle tanker and liquefaction plant on FSO

SINTEF 27/04/2015 CONCLUSIONS STTA combined with recovery plant reduces : –required peak power –energy consumption –process equipment dimensions (slightly) Economy of combination must be evaluated for each ship Compared to absorption plant a reliquefaction plant : –requires higher power –becomes more complex –produces VOC to be used as fuel Gas return to FSO requires small plant to satisfy specified reduction of NMVOC emission HCGas is a powerful tool for computing evaporation and emission from various crude types and cargo handling procedures