Fig. 6 Toluene solubles/solid carbon
However, the relationship to incomplete combustion is not shown so remarkably compared with the solid carbon.
From the above-mentioned examination, it can be recognized that the parameter to indicate incomplete combustion of the fuel oil is solid carbon.
4.5 Characteristics of Type of Residue by Part of Deposit
The confirmed items in the thermal analysis of the residue samples are summarized below by deposit part.
1] Main engine
1) Sample from piston crown part
The sample B01 shows the intermediate type, and contains the oil and the solid carbon.
2) T/C nozzle ring
Most of the samples are of Ca type residue, with few combustible components.
3) T/C blade
The residue of this part is classified into the intermediate type and Ca type.
4) T/C outlet exhaust gas pipe
The D03 sample is a typical Ca type residue, and B03 is high in solid carbon content, and of C type residue.
5) Exhaust gas economizer
The content of solid carbon is higher for every sample compared with that of the T/C residue immediately behind the engine.
The main engine residue is characterized by the fact that the carbon content becomes gradually higher from the engine toward the exhaust gas economizer, and changes from Ca type to C type.
In the highly humid residue, the mass loss caused by desorption of crystal water is seen in the relatively low temperature range (120-330℃) and the high temperature range (550-770℃). It can be recognized that the temperature range (330-550℃), between these temperature ranges, is the range where the unburnt component (solid carbon) caused by incomplete combustion is measured.
2] Generator engine (turbocharger)
The residue of the generator engine is high in carbon content compared with the main engine residue, and the possibility of incomplete combustion is considered to be high. It is also characterized by the fact that crystal water or carbon dioxide is desorbed in the high temperature range. Though the number of samples is small, the carbon content tends to be higher from the combustion chamber to the turbocharger and the funnel.
5. Conclusion
5.1 Deposit of Combustion Residues and Causes
1] As a result of the composition analysis of the combustion residue, the major components of the residue are calcium sulfide, solid carbon or iron. Calcium sulfide is the product of calcium salt in the additive of the lubricating oil which reacts with "SOx" in the exhaust gas, and the solid carbon (soot) is discharged through incomplete combustion. Because iron is contained in high quantities in the residue from the generator engine and the solid carbon, it is estimated that iron is related to the insufficient combustion of the lubricating oil supply system, and it is recognized that iron is derived from the wear of structural members in the combustion chamber.
2] Most of the combustion residues indicate strong acidity, and it is recognized that sulfur oxide (sulfuric acid) in the exhaust gas adheres to or is adsorbed by the residue.
