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What is the function of Oxidation inhibitors in turbine lube oil?

Oxidation inhibitor stabilizes the rate of oxidation.

It also passivates the metals that act catalytically to increase the rate of oxidation.

Oxidation inhibitors maintain low acidity (neutralization number) in the oil for many years.

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What is the function of Rust inhibitors in turbine lube oil?

Rust inhibitors protects the carbon-steel surfaces from rusting, when they come in contact with water entrained with the oil.

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Detergent additives in a lube oil, reduces the rate of high-temperature oxidation, formation of sludge at low temperature, and deposition of contaminants.

174

Viscosity index improvers in a lube oil, reduces the decrease in viscosity with increase in temperature.

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Antifoaming agents in lube oil, suppresses foaming of aerated oil. They also assist in the release of air from the oil.

176

Explain in brief the principle of operation of a lube oil centrifuge?

An oil centrifuge operates based on the principle that if a mixture is centrifuged, the fluids settle out radially with the fluid having the highest specific gravity outermost.

Dirty oil from the main oil tank is delivered to the purifier.

It passes through a regenerative heater/cooler. It is heated to 75°C. This is the best temperature for centrifugal separation. The oil enters the separator bowl.

Centrifugal force separates the mixture into its different densities.

The clean oil is collected by inverted cones. It is delivered to the clean-oil outlet.

The water and acids are discharged from the separator. The solids accumulate at the bottom of the bowl and are discharged regularly.

The clean hot oil is then returned back to the main oil tank.

The oil flow rate through the purifier is around 10 percent of the total oil inventory per hour.

177

Define Economics?

Economics is the social science that seeks to describe the factors which determine the production, distribution and consumption of goods and services.

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What is ‘engineering economics’?

Engineering economics, is a subset of economics for application to engineering projects.

Engineers seek solutions to problems, and the economic viability of each potential solution is normally considered along with the technical aspects.

Engineering economics involves formulating, estimating, and evaluating the economic outcomes when alternatives to accomplish a defined purpose are available.

Major areas in engineering economics are:

v  The economics of the management, operation, and growth and profitability of engineering firms;

v  Macro-level engineering economic trends and issues;

v  Engineering product markets and demand influences; and

v  The development, marketing, and financing of new engineering technologies and products.

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What is Heat transfer & what are the fundamental modes of heat transfer?

Heat transfer describes the exchange of thermal energy, between physical systems depending on the temperature and pressure, by dissipating heat.

The fundamental modes of heat transfer are conduction, convection and radiation.

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During operation, the total acidity of the turbine lube oil increases. This is caused by the fact that oil oxidizes to organic acids. Thus, the level of acidity in the oil is a good indicator about the condition of the oil. Its need for purification and conditioning will be based on the level of acidity.