BST 31212 - Fuel Characterization

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Questions and Answers

What is the primary focus of the first module in the course?

Performance evaluation techniques

Combustion fundamentals

Characterization of fuel (correct)

Boiler technology for bioenergy

How many hours are dedicated to learning about combustion fundamentals?

24 Hours

14 Hours (correct)

10 Hours

6 Hours

Which equipment is specifically used to measure the energy content of biofuel?

Gas Chromatograph

Proximate Analyzer

Bomb Calorimeter (correct)

Thermogravimetric Analyzer

What percentage of the overall assessment does the Final Assessment constitute?

60% Signup and view all the answers

What is measured in the Proximate Analyzer during laboratory sessions?

Moisture, ash, volatile matter and fixed carbon Signup and view all the answers

What is the primary benefit of using a bomb calorimeter for estimating the calorific value of fuel?

It ensures all heat released is absorbed by the surrounding water. Signup and view all the answers

Which equation represents the relationship between heat given by the fuel and heat gained by water?

$Q_1 = Q_2$ Signup and view all the answers

What type of calorific value is determined using the bomb calorimeter?

Gross calorific value Signup and view all the answers

In the calculation for calorific value, which of the following is NOT included in the total heat absorbed?

Air temperature Signup and view all the answers

What component is primarily responsible for cooling the hot gases in a bomb calorimeter?

A double coil of metal tube Signup and view all the answers

How is the net calorific value (NCV) of a fuel calculated from its gross calorific value (GCV)?

NCV = GCV - latent heat of water vapor formed Signup and view all the answers

What is the significance of the excess oxygen supplied in the bomb calorimeter?

It ensures complete combustion of the fuel. Signup and view all the answers

Which of the following statements accurately describes the heat loss correction in measurements?

It requires accurate computation to account for temperature fluctuations. Signup and view all the answers

What is the process of combustion?

The burning of a substance in the presence of air or oxygen. Signup and view all the answers

What is the primary difference between Gross Calorific Value (G.C.V) and Net Calorific Value (N.C.V)?

G.C.V includes the latent heat of water vapor formed. Signup and view all the answers

What device is used to determine the calorific value of a fuel?

A bomb calorimeter Signup and view all the answers

Which of the following statements about biomass combustion technologies is accurate?

These technologies can efficiently convert biomass into thermal energy. Signup and view all the answers

What is the formula to calculate Net Calorific Value (N.C.V)?

N.C.V = G.C.V – Latent heat of water vapor formed Signup and view all the answers

Which principle is used by calorimeters to determine calorific value?

Transferring heat from the combustion of the fuel to the water and vessel. Signup and view all the answers

What is a key goal of applying combustion principles in bio-based thermal energy generation?

To generate thermal energy sustainably from organic materials. Signup and view all the answers

In the context of biomass combustion, which of the following aspects is crucial for evaluating performance?

Type of biomass used in combustion. Signup and view all the answers

How does moisture affect the heat loss in fuels?

It increases heat loss due to superheating of vapor. Signup and view all the answers

What is the primary component of fixed carbon?

Solid fuel that remains after volatile matter is distilled off. Signup and view all the answers

What impact does high ash content have on fuel?

It reduces handling and burning capacity. Signup and view all the answers

What is the effect of moisture content on the heating value of a fuel?

It directly decreases the heating value. Signup and view all the answers

How does volatile matter influence the burning of coal?

It decreases ignition time and lengthens flames. Signup and view all the answers

What is torrefaction and how does it affect wood fuel quality?

It evaporates volatiles and moisture, upgrading quality. Signup and view all the answers

What happens to the combustion process when moisture content exceeds 55wt%?

Maintaining combustion becomes very difficult. Signup and view all the answers

What does a higher fixed carbon content indicate regarding the heating value of coal?

It provides a rough estimate of heating value. Signup and view all the answers

What is the relationship between fixed carbon composition and heating value in coal compared to wood?

Coal has higher fixed carbon than wood, resulting in higher heating value. Signup and view all the answers

Which elements are included in the ultimate analysis of fuels?

Carbon, nitrogen, oxygen, sulfur, and hydrogen. Signup and view all the answers

How does volatile matter content affect combustion efficiency?

Combustion efficiency increases with volatile matter content. Signup and view all the answers

What is the ignition point of a fuel?

The temperature at which combustion continues without external heat. Signup and view all the answers

What best describes the flash point of liquid biofuels?

The temperature at which a combustible starts burning with external heat. Signup and view all the answers

What factors influence the ignition temperature of fuels?

Oxygen levels, partial pressure, and rate of heating. Signup and view all the answers

Which statement about biomass feedstock is correct?

Biomass is composed mainly of cellulose, hemicelluloses, and lignin. Signup and view all the answers

What does combustion efficiency measure?

The heat released by the fuel compared to heat input. Signup and view all the answers

Study Notes

Course Overview

Course: BST 31212 - Combustion Technologies for Bioenergy
Duration: 06 hours for fuel characterization, 14 hours for combustion fundamentals, 10 hours for boiler technology
Assessment breakdown: 40% Continuous Assessment, 60% Final Assessment
Practical components include energy audit of biomass boiler (24 hours) and laboratory sessions for calorific value measurements

Learning Outcomes

Identify various biofuels and their combustion traits
Understand biomass combustion technologies and practical applications
Apply combustion principles for generating bio-based thermal energy
Operate and maintain low pressure steam boilers
Evaluate biomass combustion performance

Combustion Fundamentals

Combustion is the burning of a substance in air/oxygen, producing light and heat
Calorific Value: Heat released per unit mass or volume of fuel
- Gross/High Calorific Value (G.C.V/H.C.V): Total heat when fuel fully combusted and cooled
- Net/Low Calorific Value (N.C.V/L.C.V): Total heat minus latent heat of vaporized water

Measuring Calorific Value

Bomb calorimeter used for calorific value determination
Heat transfer from combustion to water and container determines calorific value
Complete combustion achieved due to high oxygen pressure and correction for temperature loss ensures accuracy

Calorific Value Calculations

Heat given by fuel equals heat gained by water, structured as:
m1 * CV = m2 * specific heat of water * (T2 - T1)
Total heat output from fuel includes contributions from fuse wire and cotton thread

Impact of Fuel Composition

Ash Content: Non-burnable impurities that increase handling costs, decrease combustion efficiency
Volatile Matter: Includes flammable gases aiding ignition and combustion; influences flame length and furnace architecture
Fixed Carbon: Solid fuel remaining post-volatilization primarily affects heating value

Proximate and Ultimate Analysis

Proximate analysis evaluates moisture, ash, volatile matter, fixed carbon
Ultimate analysis examines chemical properties (C, H, O, N, S content) of the fuel
Biomass consists mainly of cellulose, hemicellulose, lignin, and varying nitrogen and sulfur

Combustion Efficiency

Defined as heat released by fuel relative to heat input
Influencing factors include type of fuel, bed temperature, gas velocity, and excess air levels
Higher volatile matter content generally increases combustion efficiency

Ignition and Flash Points

Ignition Point: Minimum temperature for continuous combustion without external heat, varies with fuel volatility and other conditions
Flash Point: Minimum temperature for combustion to commence with external heat; dependent on fuel characteristics, not solely on ignition source temperature

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Description

This quiz focuses on the characterization of fuels, particularly in the context of combustion technologies for bioenergy. It is designed for Bachelor of Biosystems Technology honors students at Sabaragamuwa University of Sri Lanka. Test your understanding of key concepts related to fuel properties and their applications in bioenergy.