Combustion and Environmental Impact Quiz

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Questions and Answers

What gas is predominantly produced when hydrocarbons undergo complete combustion?

Sulfur dioxide (SO2)

Nitric oxide (NO)

Carbon monoxide (CO)

Carbon dioxide (CO2) (correct)

At what temperature does nitrogen in the air begin to react and form nitric acid during combustion?

2200 ᵒC

2000 ᵒC

1500 ᵒC

1800 ᵒC (correct)

Which statement correctly describes the composition of dry air as it relates to combustion?

20.9% argon, 78.1% oxygen

100% carbon dioxide

78.1% nitrogen, 20.9% oxygen (correct)

33.3% nitrogen, 33.3% oxygen

What is the term used for the mixture of gases that leaves a combustion furnace?

Flue gas (D) Signup and view all the answers

Which substance is mainly involved in the analysis of environmental pollution from combustion?

Sulfur Dioxide (SO2) (B) Signup and view all the answers

In a combustion reaction involving hydrocarbons, what is the result of incomplete combustion?

Generation of carbon monoxide (CO) (A) Signup and view all the answers

What component definitions differentiate wet basis from dry basis in gas compositions?

Water vapor presence (D) Signup and view all the answers

What percentage of the available energy in the feed is contained in activated carbon?

40% (A) Signup and view all the answers

What is the primary purpose of coal gasification?

To generate hydrogen, power, liquid fuels, and chemicals (B) Signup and view all the answers

Which statement is true regarding the water-splitting process for hydrogen production?

It can be considered green hydrogen when renewable energy is used. (A) Signup and view all the answers

What is required for the storage of hydrogen gas?

High-pressure tanks (C) Signup and view all the answers

What occurs after the impurities are removed from the synthesis gas during coal gasification?

Carbon monoxide reacts with steam to produce additional hydrogen. (C) Signup and view all the answers

What is the primary source material for charcoal production?

Wood (A) Signup and view all the answers

Which characteristic is associated with soft coke?

Burns without smoke (D) Signup and view all the answers

What percentage of virgin sugarcane does bagasse represent in weight?

20% (C) Signup and view all the answers

What temperature range is used for producing soft coke from coal?

600-650⁰C (D) Signup and view all the answers

Which manufactured solid fuel is known for leaving a solid residue with no smoke when burned?

Charcoal (A) Signup and view all the answers

What is a key characteristic that good briquettes should have?

Hard and durable (B) Signup and view all the answers

What is a unique feature of hard coke compared to soft coke?

Burns with smoke (C) Signup and view all the answers

Which of the following solid fuels is primarily derived from sugarcane?

Bagasse (D) Signup and view all the answers

What is the primary use of charcoal in many countries?

Cooking purposes (B) Signup and view all the answers

What is the main disadvantage of hard coke compared to soft coke?

Burns with smoke (D) Signup and view all the answers

What is the primary purpose of converting gas composition from dry basis to wet basis?

To write material balances on the combustion reactor (A) Signup and view all the answers

What is the term used to describe the amount of air fed to a reactor that exceeds the theoretical air requirement?

Excess Air (C) Signup and view all the answers

Given 100 mol/h of butane and 5000 mol/h of air, which reactant is in excess?

Air (D) Signup and view all the answers

What is needed to calculate the theoretical oxygen and air feed rates for combustion?

Fuel feed rate and stoichiometric equation (A) Signup and view all the answers

If the percentage of excess air is 50%, what does that signify?

Air supplied exceeds theoretical air by a factor of 1.5 (B) Signup and view all the answers

In what scenario would more of a less expensive reactant be fed into a combustion reactor?

To maximize the conversion of the valuable reactant (B) Signup and view all the answers

What is the theoretical oxygen requirement for the complete combustion of the fuel assumed to be oxidized to?

CO2 and H2O (B) Signup and view all the answers

How can the air feed rate be calculated from theoretical air and excess percentage?

Theoretical air plus the excess percentage of theoretical air (D) Signup and view all the answers

Which factor contributes to the cost when using an excess reactant in combustion reactions?

Increased pumping costs for the excess reactant (A) Signup and view all the answers

What is the primary form of hydrogen produced through steam methane reforming?

Hydrogen (A) Signup and view all the answers

What is one major byproduct of steam methane reforming?

Carbon dioxide (B) Signup and view all the answers

At what temperature range does the steam methane reforming process occur?

700–1100 °C (B) Signup and view all the answers

What is the function of the nickel catalyst in steam methane reforming?

To speed up the reaction (D) Signup and view all the answers

What is the outcome of the water gas shift reaction?

Conversion of CO to CO2 and generation of H2 (A) Signup and view all the answers

What is produced as a byproduct in methane pyrolysis?

Solid carbon (C) Signup and view all the answers

Which process generates CO2-free hydrogen?

Methane pyrolysis (D) Signup and view all the answers

What temperature is typically used in the lower-temperature water gas shift reaction?

360 °C (D) Signup and view all the answers

What type of reaction occurs during steam methane reforming?

Endothermic (C) Signup and view all the answers

What is the role of steam (H2O) in the steam methane reforming process?

To react with methane (D) Signup and view all the answers

Study Notes

Energy Sources

Stoichiometric Combustion: The theoretical combustion of a fuel when mixed with the correct amount of oxygen (air). The products are only CO2 and H2O.
Air Required: The net volume of air needed for stoichiometric combustion of different constituents (CO, C2H4, C2H6, CH4) is calculated using different figures for each. Air is primarily oxygen and nitrogen.
Air Composition: Air is mostly oxygen (20.9%) and nitrogen (79.1%), along with small amounts of other gases. For combustion calculations, nitrogen is included as well.
Hydrocarbon Fuels: Complete oxidation of a hydrocarbon fuel (CnHm) results in nCO2 + (m/2)H2O.
Combustion Reactions: The rapid reaction of a fuel with oxygen. The products (carbon dioxide, water, etc.) often have less energy value than the fuel used.
Combustion Chemistry: Key fuels used in furnaces include coal, fuel oil, gaseous fuels (methane, etc.), and liquefied petroleum gas.
Incomplete Combustion (Partial Combustion): Fuel burning that produces carbon monoxide (CO) instead of carbon dioxide (CO2). This occurs when there is insufficient oxygen.
Air Composition Considerations: The composition of air in combustion calculations is frequently simplified to 78.1% nitrogen (N2) and 20.9% Oxygen (O2). Wet and dry basis compositions are used at times.
Stack Gas (Flue Gas): The product gas leaving a combustion furnace.
Theoretical Oxygen: The moles of oxygen (or molar flow rate) needed for complete combustion of the fuel.
Theoretical Air: The quantity of air that contains the theoretical oxygen needed.
Excess Air The amount by which the air fed to a reactor exceeds the theoretical air required.
Percent Excess Air: The percent excess is calculated by comparing the air supplied to the hypothetical air needed.

Manufactured Solid Fuels

Charcoal: A solid residue from the destructive distillation of wood.
Coke: A solid residue from destructive distillation of coal, categorized as hard or soft.
Briquettes: Compacted forms of dust, culm, slack, or other small-size waste from coal, peat, coke, etc.
Bagasse: The residue of sugar cane after sugar extraction. It is fibrous and has a varying moisture content, calorific value as wood.

Hydrogen Energy

Sources: Natural gas, oil, coal, and electrolysis. Fossil fuels are predominant for industrial hydrogen production.
Steam Reforming (SMR): A method to produce hydrogen from methane or natural gas by reacting it with steam at high temperatures.
Methane Pyrolysis: Process of thermal decomposition of methane into hydrogen and carbon.
Plasma Reforming: A method to produce hydrogen and carbon black from hydrocarbons.
Coal Gasification: A process that reacts coal with oxygen and steam at high pressure and temperature to create a synthesis gas, primarily carbon monoxide and hydrogen.
Hydrogen from Water: Electrolysis using an electric current to split water into hydrogen and oxygen.
Green Hydrogen: Hydrogen produced using renewable energy sources.

Hydrogen Storage

Hydrogen Storage Methods: Gases (high pressure), liquids (cryogenic temperatures), and surfaces/solids (adsorption/absorption).
Materials-Based Storage: Hydrides (hydrogen compounds with certain metals), liquid organic hydrogen carriers, and surface storage systems (sorbents). This category includes materials that absorb or chemically bond hydrogen.
Combined Methods: Storage methods can be combined for improved energy density, such as cooled hydrogen compressed.

Biomass Energy

Biomass: Organic materials from living things, including plants.
Photosynthesis: The process plants use to store solar energy as chemical energy in biomass.
Biogas: Gas produced through anaerobic digestion of organic matter by bacteria.
Biogas Composition: Methane, carbon dioxide, and trace amounts of other gases.
Biogas Utilization: Cooking fuel, electricity generation, and a replacement for fossil fuels.
Sources of Biogas: Agricultural wastes, animal wastes, crop wastes, industrial food processing wastes, and municipal solid wastes.

Biodiesel

Biodiesel Production: Derived from fats, oils, and other organic materials through a chemical process (transesterification).
Materials: Soybean oil, recycled cooking oil, animal fats.
Biodiesel Utilization: Used as a diesel fuel replacement.

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Description

Test your knowledge on the processes of combustion, the gases produced, and their environmental implications. This quiz covers key concepts related to hydrocarbons, nitrogen reactions, pollution analysis, and coal gasification. Dive into the science behind combustion and explore the consequences of energy production.