MGO / MDO Additive Applications 26 th April 2011
Agenda MGO / MDO New & Current Fuel Issues Lubricity Background of Lubricity HFRR Test Method Effect of Additive Lubricity Study Storage Stability
Agenda MGO / MDO Injector Fouling Filter Plugging Corrosion Bacterial Contamination
New & Current Fuel Issues MGO/DO Lubricity accelerated wear of fuel pumps and injection equipment Long term storage and thermal stability (oxidation) Fouling of fuel pumps and injectors Possible contamination with FAME (bio fuels) Bacterial contamination New tests in ISO 8217 2010 for lubricity (HFRR) and stability (oxidation) very expensive High TAN fuels possible corrosion
Lubricity
What is Lubricity? Lubricity The intrinsic ability of a fluid to prevent wear on contacting metal surfaces In the case of marine engines, poor lubricity affects mechanisms that rely on the fluid being pumped for lubrication, such as fuel injection equipment (FIE)
Lubricity - Common Misconceptions Increasing the viscosity of the fuel will improve the lubricity characteristics It is the Sulphur in the fuel which offers the lubrication
Fuel Pump Tribology Two distinct regimes of lubrication in a fuel pump. Hydro-dynamic lubrication relates to the oil film between moving two metal surfaces, which prevents contact and therefore wear. This is affected to some extent by viscosity. Boundary Lubrication (lubricity) more critical in fuel pumps. Relates to lubrication where clearance is minimal, and moving metal surfaces are in contact. The fluid creates a mono molecular layer on the surface of the components to reduce friction and prevent wear.
What reduces lubricity in middle distillate fuels? Hydroprocessing at the refinery to reduce sulphur levels also removes N species O species Polyaromatic Others High sulphur fuel has natural lubricity from the minor species Remove the sulphur the lubricity is removed
Low Lubricity Consequences and Solutions Diesel lubricity problems manifested by: excessive wear of fuel injection equipment Potential solutions: Increase sulphur levels Less hydroprocessing - not possible for high sulphur crudes improved pump metallurgy - increased cost to FIE manufacturers and many old pumps already in the field use of lubricity additives - preferred choice Requirements for additive use: acceptable method for measurement of lubricity performance in real life pump situations lack of interaction with fuels, lubricants or other additives
Diesel Pump Lubricity Pump Rig Low sulphur fuels introduced in Sweden & California 1990-1 Effects on engines & FIE not recognised Failures reported in 1990-1 of distributor/rotary injection pumps Problems occurred after approximately 5000km World-wide across all manufacturers 65 million pumps have been affected Pumps rely on fuel as lubricant
Diesel Pump Rig Test Pumps specifically built by Bosch for this test Pump is operated by electric motor at various specified speeds 40 litres of is continuously cycled through the pump for 100 hours Fuel is then replaced with 40 litres of fresh fuel Repeated 10 times making a total of 1000 test hours and 400 litres of fuel. At best a test will take 6 weeks to complete
Diesel Pump Rig Rating E.O.T Pump Is Dismantled Critical Wear Components Are Rated Rating 1-3.5 = Pass, > 4 = Fail Rating System Developed By Bosch
Rating Components
HFRR / Pump Rig Correlation Source: Robert Bosch GmbH Stuttgart
Lubricity Specifications Upper specimen Lubricity test method High Frequency Reciprocating Rig (HFRR) 60 C Lubricity Specifications exist worldwide 460µm EN590 European Automotive Diesel, 1996 460µm AS3570, Australian Automotive Diesel, 2002 460µm DB 11/239, China Automotive Diesel, 2003 460µm South Korea, Petroleum Business Act, 2002 520µm USA, ASTM D975 Automotive Diesel, 2006 520µm ISO 8217:2010. Fuels with less than 0.05% Sulphur to be tested Lower Specimen
Motor Manufacturers and OEM s support limits on lubricity Worldwide Fuel Charter (WWFC) 400µm Max. Diesel Fuel Injection Equipment Manufacturers, Common Position Statement 2009 Lubricity: It is essential that the lubricity of the fuel as measured by the HFRR test specified in ISO 12156-1 meets the requirement of a wear scar diameter not greater than 460 microns. The US diesel specification (ASTM D 975-09) includes a lubricity value of 520 µm maximum (according to ASTM D 6079). It is expected that the useful operating lifetime of any mechanical component will be adversely affected by fuel with a lubricity exceeding 460 microns.
How does a lubricity additive work? Upper Specimen Lubricity Additive Lower Specimen
Impact of low sulphur & HFRR Additive Response Typical HFRR Performance Good Additive Response HFRR WSD µm 600 550 500 450 400 350 300 250 200 0 50 100 150 200 250 Lubricity Improver Treat Rate (ppm) 500ppm Sulphur 50ppm Sulphur 350ppm Sulphur 10ppm Sulphur
MGO / MDO Lubricity Testing ISO8217:2010 includes a limit for lubricity in distillate fuels by IP450-520µm So far Lintec have supplied Innospec with 126 samples of marine distillate with <1000ppm Sulphur, sourced from global ports 6 fuels with <1000ppm S have exceeded 520µm WSD (5%) Of 80 fuels with <500ppm (ISO testing requirement), 5 have failed the 520µm limit (6.25%) 1 fuel which tested at 520µm had 700ppm Sulphur, confirming ISO requirement to test only fuels with <500ppm Sulphur does not ensure safety 2 of the failed samples were bunkered from coastal USA ports, 3 from the Mediterranean and 1 from the Baltic area With the standard treat rate of Innospec Lubricity Improver, the WSD of these fuels has reduced significantly, and easily meets the specification Study will continue..
No Correlation Between Sulphur Content and WSD Sulphur Content Vs. Wear Scar 700 600 Wear Scar (Limit 520) 500 400 300 200 100 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 Sulphur Content %
No Correlation Between Viscosity and WSD Viscosity Vs. Wear Scar 700 600 Wear Scar (Limit 520) 500 400 300 200 100 0 0 1 2 3 4 5 6 Viscosity @ 40C
Solutions to Protect Your Engines Lubricity improver to restore the natural lubricity of distillate fuel oils that has been reduced in the process of removing sulphur. Lubricity improver for use in low-sulphur distillate fuel oils that possess poor lubricity characteristics. Reduce wear of fuel pumps and fuel injection equipment when operating with fuels of low intrinsic lubricity. Established and proven lubricity improving characteristics by HFRR bench test procedures. No interaction with lubricants or other fuel additives. Protect against corrosion.
Summary Automotive FIE became affected after approximately 5000km. Consider an average vehicle speed of 50km/h equates to 100 operational hours. Laboratory tests have proven that not all fuels with < 0.05% sulphur will fail ISO 8217 limit of 520µm. Tests also prove that lubricity and sulphur content do not directly correlate.
Summary Can marine fuels with >0.05% fail the test? Based on automotive experience it is assumed that max WSD of 520µm will provide sufficient engine protection. In view of the severe conditions in a large bore marine diesel engine with regard to fuel pumps (in-line, rotary, reciprocating, CR) & injectors, in order to ensure complete engine protection, the proposed limit for WSD may need lowering. Alternatively use of an established and proven lubricity improver will provide engine protection from wear and corrosion even when using ultra low sulphur distillate fuels.
Storage Stability
Middle Distillate Instability Transport fuels are a complex mixture of hydrocarbons These complex mixtures are susceptible to degradation through Auto-oxidation of hydrocarbons gum formation Acid-base reactions Salt / Sediment formation Esterification reactions Sediment formation UV (sunlight) initiated reactions These fuel degradation pathways indicate possible modes of sediment formation and doubtless occur at different rates. However, to treat each one in isolation would be an over simplification Stability additives are designed to counteract these different reactions
Stability Protection ISO 8217:2010 includes a limit for stability and oxidation Test method ISO12205 with a limit of 25g/m 3 Stabilisers are used in automotive diesel fuel production to achieve this limit
Stability Protection EN ISO 12205, European Gasoil with Additive Total Insolubles, mg/100ml 3 2.5 2 1.5 1 Basefuel Basefuel + LI5 Additive Plus 0.5 0 1 Total Insolubles reduced by 82 %
Stability Protection Unaged base fuel Aged base fuel Aged fuel containing Innospec Additive
Middle Distillate Instability Three external factors can influence stability These are Light (UV Stability) Air (Oxidation Stability) Temperature (Thermal Stability) Typically during distribution fuels are not exposed to light and therefore instability through UV light exposure not a common problem
However exposure to air and heat can occur in storage and distribution and therefore problems can occur as a result Diesel fuel stability can typically be defined as the resistance to change over time. Instability is manifested by colour change and formation of insoluble particulates and gums or by development of peroxides It is the presence of instability precursors in a diesel fuel blend which can result in insoluble matter being formed. The conditions described above of light, air and heat can all contribute to the conversion of these precursors into insoluble matter. Eventually all diesel fuel will degrade but how rapidly depends on its chemical composition and the above factors
Middle Distillate Instability Temperature variation affects the rate at which the instability precursors are converted to insoluble matter, i.e. higher temperature increases rate of instability. As an example seasonal variations in temperature of up to 20 C can occur during pipeline distribution in the USA Oxygen is important when discussing fuel instability and most degradation mechanisms include an oxidation step. Often fuel may be protected through covering by an inert gas, a so called nitrogen blanket. This is not always practical however and therefore during distribution most fuel is prone to oxidation. Oxygen can help promote polymerisation and acidbase reactions which result in the formation of insoluble matter and gums Therefore both thermal and oxidative effects are important factors in contributing to fuel instability. They result in the same effect, i.e. gum formation and insoluble matter and are difficult to protect against as fuel will be exposed to oxygen and temperature variations during distribution and use. Stabilisation through additive treatment is an extremely effective way of protecting against thermal and oxidative initiated stability Innospec additives contain stabiliser which can help protect against thermal and oxidation stability
Injector Fouling & Filter Blocking
Fuel Injector Cleanliness Innospec additive contains a powerful detergent which prevents formation of, and removes existing, deposits caused by fuel decomposition results in optimal fuel spray pattern being maintained Provides a number of benefits Better fuel economy Reduced emissions Improved engine durability
Injector Cleanliness Injectors from additivated fuel Injectors from basefuel
Detergency Performance Testing performed in severe engine test developed to measuring nozzle fouling propensity of diesel fuel (CEC F- 23-01 Peugeot XUD9) Nozzle fouling measured through air flow rig after 10 hour test cycle Acceptable performance observed at <85% nozzle fouling. Greater protection at <70 % LI5 Plus offers excellent protection against injector nozzle fouling % Nozzle Fouling 90 85 80 75 70 65 60 55 50 Base fuel Base fuel + Octamar LI- 5 Plus
Typical High Pressure Common Rail fuel system High pressure pump Common Rail Pressure-side filter Lift pump Injectors Injected fuel Suction filter Fuel tank Return source - Cummins Inc. SAE Oct 2008
Fuel Filter Plugging
Fuel Filter Plugging Middle distillate fuel instability can result in increased rates of filter plugging Filter deposits can be formed through instability caused by the fuel exposed to high temperature and pressure Such high temperatures are commonplace in high pressure fuel injection systems used in modern diesel engines
Fuel Filter Plugging (IP387) Industry standard tests exist to measure the filter blocking tendency of a middle distillate Tests measures the pressure difference across a filter Filter blocking tendency (FBT) is calculated and an FBT <1.41 is desirable to avoid filterability problems Fuel Basefuel Basefuel + Additive Basefuel Basefuel + Additive Filter Blocking Tendency 1.49 1.00 2.52 1.00
Fuel Filter Plugging Fuel Filters from untreated fuel Fuel Filters from additivated fuel
Corrosion
Anti-Corrosion Additive will prevent corrosion of metals when water is present in fuel tanks ASTM D665A procedure % Corrosion NACE rating Basefuel 100 E (fail) Steel probe immersed in fuel/water @ 60 C for 24 hours Typical results in middle distillate Basefuel + Additive 0 A (pass)
Bacterial contamination
Types of Microbes Found in Fuel Systems Bacteria Single cells Typically 1-10 microns) Rapid growth (20-30 minute generation time) 1 cell can replicate into > 2 million cells in 7 hrs Mould Type of Fungi Multi-cellular Filaments Aerobic Yeast Type of Fungi Single Cells Both aerobic and anaerobic Typically 3-4µm All use the hydrocarbon as a food source
Microbial Contamination Microbes cannot grow in fuel alone Water is required for microbial life, growth, & reproduction Microbes, in general, live at the fuel water interface Water bottoms Any place a droplet of water is present Diesel Fuel Bio-mass Water
Biocide Applications Shock Treatment / Quick Kill Used to eliminate existing fuel contamination Typically dose 100 to 1000ppm If contamination is severe, dead biomass may need to be filtered from the fuel after treatment Follow by preventative treatment to stop re-contamination Preventative Treatment Used as part of routine housekeeping Typical dose 100 to 250ppm Monitor regularly and re-treat when microbial activity starts to show