24 Questions
What is the primary purpose of fractional distillation of crude petroleum?
To separate various fractions of hydrocarbons
What is the term for the process of breaking high molecular weight hydrocarbons into low molecular weight compounds?
Cracking
What is the primary cause of knocking in an internal combustion engine?
Premature combustion of the air-fuel mixture
What is the purpose of adding Tetraethyl Lead (TEL) to gasoline?
To increase the octane rating of the fuel
What is the inverse function of a fuel's ignition delay?
Cetane number
What is the primary property of diesel fuel that affects engine performance and emission?
Cetane number
What is the purpose of the cetane number in diesel fuel?
To measure the fuel's ignition delay
What is the effect of increasing the cetane number of diesel fuel?
Decrease in ignition temperature
During what process is LPG obtained as a byproduct?
All of the above
What is the main component of CNG?
Methane
What is the caloric value of LPG?
26200 kcal/Nm³
What is a beneficial property of LPG in regards to鋼alloys?
It is non-corrosive to steel and copper alloys.
What is the main use of LPG in domestic and industrial applications?
As a domestic fuel
What is CNG mainly composed of?
Methane and Ethane
What is a benefit of using CNG over petrol and diesel?
It produces fewer greenhouse gases
What is a property of CNG that makes it efficient in engines?
It has a high calorific value
What is the purpose of the oxygen cylinder in the combustion reaction?
To provide oxygen for the fuel combustion
What is the process of separating crude oil into different fractions based on their boiling points?
Fractional Distillation
What is the term for the uncondensed residue left in the iron retort after fractional distillation?
Asphalt or Pitch
What is the purpose of the horizontal trays in the fractionating tower?
To provide a pathway for the vapors to condense
What is the term for the temperature at which a fuel ignites?
Flash Point
What is the process of breaking down large molecules into smaller ones?
Cracking
What is the term for the detonation of a fuel inside an engine, resulting in a knocking sound?
Knocking
What is the term for the measure of a fuel's resistance to knocking?
Octane Number
Study Notes
Fractions Obtained in Fractional Distillation
- Crude petroleum undergoes fractional distillation to produce various fractions
Cracking
- Process of breaking high molecular weight hydrocarbons into low molecular weight compounds like gasoline, diesel, olefins, etc.
- Thermal cracking: carried out in the presence of heat
- Catalytic cracking: carried out in the presence of a catalyst
Knocking
- Premature combustion of part of the compressed air-fuel mixture in the IC engine cylinder
- Causes a sharp sound and sudden pressure rise
- Prevented by adding anti-knocking agents like Tetraethyl Lead (TEL) in gasoline
Octane Number
- Measure of a fuel's ability to resist knocking when ignited with air in an IC engine
- Higher octane number indicates lower knocking property
- Can be increased by adding TEL, but increases air pollution by emitting lead particles
Cetane Number
- Measure of a diesel fuel's ignition properties
- Percentage of hexadecane present in a mixture of hexadecane and 2-methyl naphthalene
- Higher cetane number indicates lower ignition temperature and better fuel performance
Gaseous Fuels: LPG, CNG, Biogas
- LPG (Liquefied Petroleum Gas): byproduct of crude oil distillation or heavy oil cracking
- Composition: Ethane (0.20%), Propane (57.30%), Butane (41.10%), Pentane (1.40%)
- Properties: highly flammable, colorless, odorless, high calorific value, non-corrosive
Uses of LPG
- Domestic fuel (liquid butane) and industrial fuel (liquid propane)
- Motor fuel, as it mixes with air and burns cleanly
- Used in aerosol industries
CNG (Compressed Natural Gas)
- Made by compressing natural gas to less than 1% of its volume at standard atmospheric pressure
- Composition: CH4 (methane) = 88.5%, C2H6 (ethane) = 5.5%, C3H8 (propane) = 3.7%, etc.
- Properties: cheaper than petrol or diesel, ignition temperature = 540°C, odourless, non-toxic, non-corrosive, lightweight, high calorific value
Calorimeter
- Measures heat produced by fuel combustion
- Consists of a bomb, copper calorimeter, thermometer, and stirrer
- Initial temperature of water in the calorimeter is measured by a thermometer
- Oxygen is admitted into the bomb, and the fuel is ignited by an electric circuit
- Heat produced by combustion raises the temperature of the calorimeter water, which is recorded by the thermometer
This quiz covers the fractions obtained in the fractional distillation of crude petroleum, including cracking and its types. Learn about the process of breaking high molecular weight hydrocarbons into low molecular weight compounds.
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