Troubleshooting Investigative Analysis

Through advanced analytical methods, we are able to detect unusual components and/or contaminants in the fuels.

Purpose

 

Every day ships experience operational difficulties of some sort. It may be minor irregularities like a clogged filter or more severe cases like massive filter clogging, centrifuge sludging, fuel pump sticking, scuffing, combustion problems etc.

Even ships with good household and maintenance practices may experience problems if the fuel in use contains contaminants; is unstable; has poor cold flow properties; has poor ignition combustion properties; or has not been treated efficiently onboard.

Costs related to such cases can be significant, not only due to the spare parts costs, but also off-hire. Additionally, the risks and consequences of losing power in areas with a lot of traffic must be considered.

Over the years, VPS has assisted many customers in solving trouble shooting cases and have developed in-house methods based on a combination of advanced technologies and field experience. Through advanced analysis methods, we are able to detect unusual components and/or contaminants in the fuels. In addition, we analyze deposits and sludge and also examine the damaged engine components to develop an understanding of what has happened.

Our Approach & Process

 

Although no industry accepted list of the components normally found in heavy fuel oils exists, VPS has wide and long experience working with fuel oils. Based on this and in combination with our specialized testing work, we have deep understanding of fuel composition and the operational difficulties that may be encountered.

When required by clients, our Technical Advisers are able to assist in trouble shooting by visiting the vessel to discuss the case with ship’s staff and to provide support in investigations as well as collection of information and evidence during inspection of the installation.

Solid contaminants
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Through a combination of filtration and identification techniques, it is possible to distinguish between organic and inorganic particles that may be responsible for filtration problems

A high content of inorganic particles (like cat fines, sand and iron) in the fuel may clog filters. In addition to compromising filter operation, these particles are often abrasive in nature and should be removed in the fuel treatment system onboard.

Particles that are organic in nature (e.g. polymers) are also known to cause filtration problems. VPS’ Solid Contaminant Testing service has proven very useful in the detection of polymers like polyethylene, polystyrene and polypropylene.

Gas Chromatography - Mass Spectrometry (GC-MS)
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A fuel is a complex blend of many organic components. One method to identify the individual components of the fuel is Gas Chromatography – Mass Spectrometry (GC-MS).

The individual components are separated through heating and vaporization (Gas Chromatography) before passing through the mass spectrometer. A mass spectrum is prepared and by comparing against a library of known molecules, it is possible to identify the composition of the fuel oil.

Different pre-treatment methods can be applied for the GC-MS analysis:

  • Head-space GC-MS Fastest GC-MS version. Not suitable for detecting components of low volatility and high boiling points.
  • GC-MS analysis on vacuum distillates Distillation under vacuum lowers the boiling point of the various components, ie. more substances can be detected and identified.
  • GC-MS on acid extract For detecting and identifying organic acids.
Separability Number

This procedure describes a rapid and sensitive method for estimating the stability reserve of an oil. The stability reserve is estimated in terms of a separability number, where a low value of the separability number indicates that there is a stability reserve within the oil. When the separability number is between 0 to 5, the oil can be considered to have a high stability reserve and asphaltenes are not likely to flocculate. If the separability number is between 5 to 10, the stability reserve in the oil will be much lower. However, asphaltenes are, in this case, not likely to flocculate as long as the oil is not exposed to any worse conditions, such as storing, aging, and heating. If the separability number is above 10, the stability reserve of the oil is very low and asphaltenes will easily flocculate, or have already started to flocculate.

 

 

Fuel Combustion Analyzer (FCA)
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Ignition and combustion fuel properties have an impact on the engine’s combustion process. Poor ignition properties may lead to starting difficulties, knocking or problems operating at low load maneuvering, while combustion related issues may result in increased exhaust gas temperatures and increased load on the exhaust system. It should be noted that engine design and operational pattern have an impact on how sensitive the engines are to the ignition/combustion properties of a fuel. In the 1980s, the Calculated Carbon Aromaticity Index (CCAI) was developed to evaluate the ignition properties of a fuel. The CCAI is calculated based on the fuel’s density and viscosity. The industry has developed the IP541/06 lab method in which a sample of the actual fuel is injected into a combustion chamber at reference pressure and temperature. The result is used to calculate an Estimated Cetane Number (ECN) that is useful for evaluating the impact of the fuels’ ignition/combustion properties on engine performance. Details of the method and the correlation to engine performance can be found on CIMAC’s website.
Fuel System Check programme (FSC)

FSC monitors the condition of the fuel oil system and the effectiveness of the fuel oil treatment plant. Please also refer to VPS’ Catfines (Al+Si) Size Distribution service screening, which can be used in conjunction with the FSC programme to ensure adequate treatment is being obtained

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Cat Fines Size Distribution (CSD)

VPS has developed the Cat Fines Size Distribution Screening (CSD) service to specifically look at the cat fines size ranges in a given fuel.

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Sludge/deposit analysis

Analysis of sludge/deposits may assist in finding the cause of the operational difficulties experienced by the ship.

Many operators have experienced filter clogging and deposit formation during operation. In the worst cases, such incidents can be a safety hazard. Finding the cause is not always easy as many factors including fuel composition, maintenance and operational patterns may influence the difficulties experienced.

Analysing the sludge/deposit may assist in finding the source of the problem. No industry acknowledged method exists for such cases, however by combining the various investigative analysis techniques, it has proven possible to link the fuel or maintenance/operation to the experienced difficulties.