Fuels and Solid Fuels Overview

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Questions and Answers

What type of crude oil is primarily composed of saturated hydrocarbons and is generally semi-solid?

Asphalt-based crude

Naphthene-based crude

Paraffin-base crude (correct)

Mixed base crude

What method is used to bring oil to the surface during drilling?

Vacuum extraction

Steam injection

Hydraulic fracturing

Air-lift pumping (correct)

Which type of crude oil contains both paraffins and naphthenes but is rich in waxes?

Cyclic crude

Paraffin-base crude

Asphalt-based crude

Mixed base crude (correct)

Approximately what percentage of crude oil produced currently falls under the mixed base category?

90% Signup and view all the answers

What role does hydrostatic pressure play in the extraction of oil?

It pushes oil to the surface. Signup and view all the answers

What does the gross calorific value (GCV) represent?

The total heat evolved when a fuel is burned in oxygen with water in liquid state. Signup and view all the answers

How is the net calorific value (NCV) defined in relation to GCV?

NCV is less than GCV by the heat of condensation of water vapors. Signup and view all the answers

Which element is NOT considered in Dulong's formula for calculating calorific value?

Phosphorus Signup and view all the answers

What is the latent heat of steam used in LCV calculations?

587 kcal/kg Signup and view all the answers

What does the presence of 90% carbon imply about the type of coal?

It is bituminous coal with high calorific value. Signup and view all the answers

Which hydrocarbons are predominantly found in petroleum?

Hydrocarbons, paraffins, naphthenes, and aromatics Signup and view all the answers

What is the primary source of crude oil?

Organic matter from marine sediments Signup and view all the answers

Which of the following metals is NOT commonly found in petroleum?

Sodium (Na) Signup and view all the answers

What is the primary characteristic of a substance classified as fuel?

It must contain combustible elements. Signup and view all the answers

Which of the following is NOT a method for classifying fuels?

According to calorific value. Signup and view all the answers

What is the transformation sequence from vegetable matter to anthracite coal?

Peat → Lignite → Bituminous Coal → Anthracite Signup and view all the answers

Which element is typically NOT part of the composition of coal?

Nitrogen Signup and view all the answers

What is the average calorific value range of wood?

4000 to 6400 Btu/lb Signup and view all the answers

Which analysis method determines the percentages of volatile matter, fixed carbon, ash, and moisture in coal?

Proximate analysis Signup and view all the answers

What does combustion primarily convert in fuels?

Chemical energy into heat energy Signup and view all the answers

Which type of fuel has extensive application in engineering and is derived from prehistoric plants?

Coal Signup and view all the answers

Study Notes

Fuels

Fuels react with oxygen to produce heat
Fuels contain combustible elements such as carbon, hydrogen, sulfur, etc.
Fuels are classified according to their physical state (solid, liquid, or gas) and how they are obtained (naturally or manufactured).

Solid Fuels

Wood is derived from tree trunks and branches
Wood typically contains 15% moisture
Its application as an engineering fuel is limited due to its low calorific value (4000-6400 Btu/lb)
Coal is a highly carbonaceous solid fuel formed from prehistoric plants
Coal contains carbon, hydrogen, oxygen, and non-combustible inorganic matter (ash)
Coal Metamorphism: Stages of coal formation: peat, lignite, bituminous coal, anthracite
With progressive transformation, carbon content increases, while moisture, volatile matter, and oxygen content decrease
Coal's calorific value and hardness increase with each stage.

Analysis of Coals

Proximate Analysis: Determines the percentages of volatile matter, fixed carbon, ash, and moisture in air-dried coal.
Ultimate Analysis: Determines the percentages of carbon, hydrogen, oxygen, nitrogen, and sulfur in coal

Coke

Coke is formed by carbonizing bituminous coal.

Calorific Value

Gross Calorific Value (GCV) : Heat liberated during combustion of a unit mass of fuel, assuming all water produced is in liquid form
Net Calorific Value (NCV): Heat liberated during combustion of a unit mass of fuel, assuming all water produced is in vapor form
NCV is always less than GCV by the amount of heat needed to vaporize water.
Dulong's Formula: Calculates calorific value from the chemical composition of fuel:
- GCV = [8080C + 34500(H - O/8) + 2240S] kcal/kg
- NCV = [GCV - 9(H)*587] kcal/kg
Problem 1:
- Coal composition: C=90%, O=3%, S=0.5%, N=0.5%, ash=2.5%
- NCV = 8490.5 kcal/kg
- Calculate H and GCV

Liquid Fuels

Petroleum (crude oil) is a mixture of hydrocarbons, mainly paraffins, naphthenes, and aromatics
Petroleum contains trace amounts of metals like silicon, iron, aluminum, calcium, magnesium, and nickel.
It is formed from organic matter (marine sediments) transformed by anaerobic bacteria under pressure and heat over millions of years.

Classification of Petroleum

Paraffin-base crude: Composed of saturated hydrocarbons up to C35H72, including waxes.
Asphalt-base crude: Mainly contains naphthenes and cycloparaffins, with lower proportions of paraffins and aromatics.
Mixed base crude: Contains both paraffin and asphalt-base compounds, but is rich in waxes.
- Approximately 90% of current crude oil production falls into this category.

Petroleum Extraction

Drilling: Wells drilled to reach oil reservoirs
Hydrostatic Pressure: Oil is brought to the surface using the pressure of natural gas or by compressed air forced through a coaxial pipe system.
Crude oil is sent to refineries for processing and refinement.

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Description

This quiz covers the basics of fuels and solid fuels, focusing on their chemical composition and classifications. Learn about various types of solid fuels, including wood and coal, as well as the stages of coal transformation. Test your understanding of fuel properties and analyses.