Introduction and Types of Combustion

  • Combustion is a high-temperature chemical reaction between a fuel and an oxidant.
  • It is an exothermic process that produces oxidized products, often in the form of smoke.
  • A flame is a characteristic indicator of combustion, but it is only visible when substances vaporize.
  • Activation energy is required to initiate combustion, but a flame can sustain the reaction.
  • Combustion can be a complex sequence of radical reactions, often producing incandescent light.
  • Complete combustion occurs when a fuel burns in oxygen and produces carbon dioxide and water.
  • Incomplete combustion occurs when there is insufficient oxygen, resulting in carbon monoxide and carbon.
  • Pyrolysis, the decomposition of fuel before combustion, is common in fuels like diesel oil and wood.
  • Incomplete combustion can lead to the production of noxious particulate matter and toxic gases.
  • Combustion devices, such as burners and catalytic converters, can improve the quality of combustion.

Air Pollution and Combustion

  • Combustion in air can release nitrogen oxides (NOx), which contribute to air pollution.
  • High temperatures favor the combustion of nitrogen, leading to the formation of NOx.
  • Fuel gas cleaning and catalytic converters are often required to reduce emissions and comply with regulations.
  • Combustion in air also produces smoke that may contain unburned or partially oxidized products.
  • The equilibrium of combustion in air is usually on the side of the products, but complete combustion is challenging to achieve.

Applications of Combustion

  • Combustion is the main method used to produce energy for cooking, electricity generation, and heating.
  • Fossil fuels like coal and oil, as well as renewable fuels like firewood, are commonly used for combustion.
  • Combustion is the primary reaction used to power rockets and is crucial for space exploration.
  • Waste incineration is another application of combustion, both for nonhazardous and hazardous waste.
  • Combustion is a controlled chemical reaction that humans discovered through campfires and bonfires.

Combustion and Oxidants

  • Oxidants used for combustion have high oxidation potential, such as atmospheric or pure oxygen.
  • Chlorine, fluorine, chlorine trifluoride, nitrous oxide, and nitric acid can also act as oxidants.
  • Hydrogen burns in chlorine to form hydrogen chloride, releasing heat and light.
  • Combustion can be catalyzed by substances like platinum or vanadium, as seen in the contact process.
  • The amount of air required for complete combustion is known as theoretical air, while excess air is needed for optimal combustion.

Environmental and Health Effects of Combustion

  • Incomplete combustion produces oxides that combine with water and oxygen in the atmosphere, leading to acid deposition or acid rain.
  • Acid deposition harms aquatic organisms and kills trees.
  • Nitrogen oxides and hydrocarbon pollutants contribute to the formation of ground-level ozone, a major component of smog.
  • Breathing carbon monoxide causes headache, dizziness, vomiting, and nausea.
  • High levels of carbon monoxide can lead to unconsciousness or death.
  • Moderate to high levels of carbon monoxide exposure increase the risk of heart disease.

Combustion Mentions

Combustion Data Sources

Reference URL
Knowledge Graph