Unit 3: Energy and Fuels
Course Code: CHM-DSC-353
Paper Name: Industrial Chemistry
1. Solid Fuels: Coal
Coal is a fossil fuel formed from plant remains. Its quality is determined by the percentage of carbon.
- Types: Peat (lowest C), Lignite, Bituminous, and Anthracite (highest C).
- Carbonization: The process of heating coal in the absence of air to produce Coke, Coal Tar, and Coal Gas.
- Coal Gasification: Production of "Syngas" (CO + H2) from coal to be used as a fuel or chemical feedstock.
2. Liquid Fuels: Petroleum
Crude oil is a complex mixture of hydrocarbons. It is processed in refineries to produce useful fuels.
Fractional Distillation
Components of crude oil are separated based on their boiling points in a tall fractionating column.
- Cracking: The process of breaking down long-chain hydrocarbons into smaller, more valuable molecules like gasoline.
- Reforming: Structural alteration of molecules (e.g., straight chain to branched) to improve fuel quality.
3. Fuel Quality Parameters
The performance of an internal combustion engine depends on the "knocking" characteristics of the fuel.
4. Gaseous Fuels
Gaseous fuels are preferred in industries due to their high calorific value and clean burning nature.
- LPG (Liquefied Petroleum Gas): Primarily Butane and Propane. Used for domestic heating.
- CNG (Compressed Natural Gas): Primarily Methane. Used as an eco-friendly transport fuel.
- Water Gas: A mixture of CO and H2, produced by passing steam over red-hot coke.
- Producer Gas: A mixture of CO and N2, produced by passing air over red-hot coke.
5. Renewable Energy and Future Fuels
To reduce carbon footprints, the industry is shifting toward sustainable energy sources.
- Solar and Wind Energy: Non-polluting, inexhaustible sources of power.
- Biofuels: Fuels derived from biomass (e.g., Bio-ethanol from sugarcane, Biodiesel from vegetable oils).
- Hydrogen Fuel: Considered the "fuel of the future" because its combustion produces only water vapor. It is stored using high-pressure tanks or metal hydrides.
6. Exam Focus: Tips and FAQs
Exam Tips
- Calorific Value: Remember that Gaseous fuels generally have higher calorific values than solid fuels.
- Anti-knocking Agents: Mention that TEL (Tetraethyl Lead) was used to increase Octane number but is now replaced by MTBE due to lead toxicity.
- Reactions: Practice the water gas reaction: C + H2O → CO + H2.
Frequently Asked Questions
Q: What is the difference between LPG and CNG?
A: LPG consists of heavier hydrocarbons (butane/propane) that liquefy under moderate pressure, while CNG is mostly methane and remains a gas even under high pressure.
Q: Why is Iso-octane given an octane rating of 100?
A: Because it has excellent anti-knock properties due to its highly branched structure.
Q: What is the composition of Natural Gas?
A: It typically contains 70-90% Methane (CH4) with smaller amounts of Ethane, Propane, and Butane.