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liquids, semisolids, or solids” [1]. The crude oil, generally brownish green to black
liquid substance, is found throughout the world at different depths of earth’s crust.
The location of petroleum inside the earth crust is generally discovered by oil drilling after a geological survey of the land or seabed. The crude oil drilled from the
earth’s crust is in the form of a water-in-oil emulsion. The crude oil also has a very
high concentration of salts due to brine droplets emulsified in the oil. The salt concentration may vary from a few hundred ppm to several thousand ppm. The water
content in emulsion varies typically from 5% to 10% and can go up to 50%, depending upon the source of the oil [2, 3].
The water or brine water (salted water) present in crude oil can cause severe
problems in the downstream processing of refineries such as deactivation and poisoning of the catalyst [2, 4]. The salts present in the crude oils are also responsible
for corrosion in the processing equipment, thereby leading to high maintenance
costs in the refineries. Petroleum consists of hydrocarbons of different molecular
weights and chemical structure and is refined and separated based on demands in
various applications. The separation is on account of their boiling points and is
most easily done in distillation columns. The different fractions are kerosene,
gasoline (petrol), and chemical reagents (polymers) and are used for making plastics and in various applications in pharmaceutical and petrochemical industries.
To achieve all these fractions during refineries, several downstream reactions are
performed in the presence of a catalyst. The performance of the catalyst can be
adversely affected by the salts present in crude oil. Therefore, for safe and efficient refineries operation, it is critical to remove the brine from the crude oil. The
overall procedure of separation of water (brine) from crude oil is generally known
as desalting.
The size of water droplets in the water-in-oil crude oil emulsions may vary from
0.1 to 100 μm [2–5]. The ease of separation of water and oil in the emulsion depends
on the stability of the emulsion. Several parameters that can directly or indirectly
affect the stability of the emulsion can be listed as % water content, pH of wash
water, interfacial tension, the nature of asphaltene and naphthenic acids, nature of
brine (such as NaCl, CaCl 2 ), the conductivity of emulsion phase, demulsifier dosage, API value of crude oil, processing temperature, and electrical and physical
properties of an emulsion [6–13]. Various techniques such as gravity separation,
chemical treatment, membrane separation, centrifugation, and electrocoalescence
are available for breaking the water-in-oil emulsion [2, 14–21]. All the individual
methods have their advantages and disadvantages and are discussed in detail in this
chapter.
The chapter is organized as follows: the nature of crude oil, classification, and
their properties are discussed, followed by the factors affecting the stability of the
water-in-oil emulsion. Breaking of water-in-oil emulsion, also known as oil demulsification, is discussed next. This is followed by the mechanism and method of
demulsification. The chapter concludes with a detail procedure and mechanism of
breaking of the water-in-oil emulsion by using electrocoalescence technique.
V. Anand and R. M. Thaokar
liquids, semisolids, or solids” [1]. The crude oil, generally brownish green to black
liquid substance, is found throughout the world at different depths of earth’s crust.
The location of petroleum inside the earth crust is generally discovered by oil drilling after a geological survey of the land or seabed. The crude oil drilled from the
earth’s crust is in the form of a water-in-oil emulsion. The crude oil also has a very
high concentration of salts due to brine droplets emulsified in the oil. The salt concentration may vary from a few hundred ppm to several thousand ppm. The water
content in emulsion varies typically from 5% to 10% and can go up to 50%, depending upon the source of the oil [2, 3].
The water or brine water (salted water) present in crude oil can cause severe
problems in the downstream processing of refineries such as deactivation and poisoning of the catalyst [2, 4]. The salts present in the crude oils are also responsible
for corrosion in the processing equipment, thereby leading to high maintenance
costs in the refineries. Petroleum consists of hydrocarbons of different molecular
weights and chemical structure and is refined and separated based on demands in
various applications. The separation is on account of their boiling points and is
most easily done in distillation columns. The different fractions are kerosene,
gasoline (petrol), and chemical reagents (polymers) and are used for making plastics and in various applications in pharmaceutical and petrochemical industries.
To achieve all these fractions during refineries, several downstream reactions are
performed in the presence of a catalyst. The performance of the catalyst can be
adversely affected by the salts present in crude oil. Therefore, for safe and efficient refineries operation, it is critical to remove the brine from the crude oil. The
overall procedure of separation of water (brine) from crude oil is generally known
as desalting.
The size of water droplets in the water-in-oil crude oil emulsions may vary from
0.1 to 100 μm [2–5]. The ease of separation of water and oil in the emulsion depends
on the stability of the emulsion. Several parameters that can directly or indirectly
affect the stability of the emulsion can be listed as % water content, pH of wash
water, interfacial tension, the nature of asphaltene and naphthenic acids, nature of
brine (such as NaCl, CaCl 2 ), the conductivity of emulsion phase, demulsifier dosage, API value of crude oil, processing temperature, and electrical and physical
properties of an emulsion [6–13]. Various techniques such as gravity separation,
chemical treatment, membrane separation, centrifugation, and electrocoalescence
are available for breaking the water-in-oil emulsion [2, 14–21]. All the individual
methods have their advantages and disadvantages and are discussed in detail in this
chapter.
The chapter is organized as follows: the nature of crude oil, classification, and
their properties are discussed, followed by the factors affecting the stability of the
water-in-oil emulsion. Breaking of water-in-oil emulsion, also known as oil demulsification, is discussed next. This is followed by the mechanism and method of
demulsification. The chapter concludes with a detail procedure and mechanism of
breaking of the water-in-oil emulsion by using electrocoalescence technique.
V. Anand and R. M. Thaokar