Fuel dilution

The ethylene feedstock used in most plants is of high purity and contains 200—2000 ppm of ethane as the only significant impurity. Ethane is inert in the reactor and is rejected from the plant in the vent gas for use as fuel. Dilute gas streams, such as treated fluid-catalytic cracking (FCC) off-gas from refineries with ethylene concentrations as low as 10%, have also been used as the ethylene feedstock. The refinery FCC off-gas, which is otherwise used as fuel, can be an attractive source of ethylene even with the added costs of the treatments needed to remove undesirable impurities such as acetylene and higher olefins. Its use for ethylbenzene production, however, is limited by the quantity available. Only large refineries are capable of deUvering sufficient FCC off-gas to support an ethylbenzene—styrene plant of an economical scale. 

Black, viscous residuum direc tly from the still at 410 K (390°F) or higher serves as fuel in nearby furnaces or may be cooled and blended to make commercial fuels. Diluted with 5 to 20 percent distillate, the blend is No. 6 fuel oil. With 20 to 50 percent distillate, it becomes No. 4 and No. 5 fuel oils for commercial use, as in schools and apartment houses. Distillate-residual blends also serve as diesel fuel in large stationaiy and marine engines. However, distillates with inadequate solvent power will precipitate asphaltenes and other high-molecular-... 

Fuel dilution of oil in an engine weakens the oil film strength, sealing ability, and detergency. Improper operation, fuel system leaks, ignition problems, improper timing, or other deficiencies may cause it. Fuel dilution is considered excessive when it reaches a level of 2.5 to 5 per cent. 

Turns, S. R., F. H. Myhr, R. V. Bamdaru, and E. R. Maund. 1993. Oxide of nitrogen emission from turbulent jet flames Part 11 — Fuel dilution and partial premixing effects. Combustion Flame 93 255-69. 

In a diesel engine the contamination comes from the above and additional sources such as (a) soot as a normal by-product of diesel engine will increase the viscosity of the oil and become abrasive as its level increases in the oil (b) the fuel dilution will reduce the film strength of the oil to a point where accelerated wear occurs (c) the fuel dilution will reduce the flash-point of the oil (d) a diesel engine oil will also be exposed to the formation of acid from the sulfurized fuel max.5% a diesel engine will have a high TBN to assist it in combating the acid formation. 

Antiskid systems (road resurfacing epoxies) Skid resistance Resistance to water, de-icing salts, fuels, dilute acids and alkalis For deslicking a smooth roadway... 

Rats dosed dermally with 1000 ml kg diesel fuel per day, 5 day week" for 2 weeks had demonstrated weight loss, reduced liver weights, serum glucose, serum protein, and serum cholesterol, as well as a reduction in hemoglobin, hematocrit, red cell count, and blood lymphocyte counts. Marine diesel fuel produced lesions in the kidneys of mice treated dermally with 50 pi undiluted fuel three times a week for 60 weeks. Kidney lesions were not observed in a second dermal study in which B6C3F1 mice were treated with up to 500 ml kg of marine diesel fuel diluted in acetone five times per week for 103 weeks. 

As for all additives, interactions with other additives in solution, Fig. 3.16, and competition for surface reaction sites together with the effect of environmental factors such as temperature, blow-by gases, water and fuel dilution have variable effects on the formation of the film. Because ZDDPs are much more widely used as antiwear performance additives compared to other classes of compounds, these additive effects will now be discussed in greater detail than has been the case for other classes of anti-wear/friction additives. In particular the influence of structure, concentration, dispersant, detergent, antioxidancy and friction modifier on friction and wear will be discussed. In addition the influence of NO c and H2O will be briefly illustrated. 

Products will need development and optimization for alcohol- and vegetable oil-based fuels. Evolution is likely to be both composition, to tolerate high levels of fuel dilution, and dispersancy to handle new types of sludge that are likely to be produced. 

Reduction of diesel exhaust emissions has, in some cases, led to engines producing more soot within the lubricant, exacerbated by extended oil drain intervals leading to more soot-related wear. Some low-emission engines have also experienced increased fuel dilution, causing premature ageing of the lubricant. These issues have presented the lubricant formulator with an array of problems that must be addressed. 

Changes in viscosity in service arise from either fuel dilution or suspended matter. Assuming no other adverse symptoms, changes in viscosity of 20-25% can be tolerated. Contamination by marine diesel or distillate fuel reduces viscosity contamination by heavy fuel oil increases viscosity. 

The Fuel Sniffer Sensor The Fuel Sniffer is a portable fuel dilution meter that can be used in the laboratory or in the field to provide rapid measurements of fuel contamination in engine oil. Developed in collaboration with the US navy, the Fuel Sniffer employs a surface acoustic wave (SAW) vapour microsensor to measure the concentration of distillate fuel in used diesel lubricating oil samples. The sensor quantifies the absorbed hydrocarbons by a change in frequency. The instrument samples the head space in the sample bottle and calculates the percent of fuel... 

Low nominal Decreasing Alert Increasing fuel dilution... 

Table 16.7 is an example of viscosity limits for a medium speed diesel engine selected from the culled sample population in Fig. 16.22. These limits will reliably indicate fuel dilution and oil oxidation problems for the specific lubricant and fuel used. 

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