Air Pollution Control Engineering - Week 12 Quiz
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Questions and Answers

What is a direct environmental impact of SO2 emissions?

  • Reduction in crop yield
  • Increase in aquatic biodiversity
  • Decreased respiratory health
  • Acid rain phenomenon (correct)

What is the result of the reaction between SO2 and water?

  • H2CO3
  • NO2
  • H2SO3 (correct)
  • H2SO4

What is the normal pH of rainwater before it is affected by pollutants?

  • 6.8
  • 4.5
  • 7.0
  • 5.6 (correct)

Which of the following is NOT an impact of acid rain?

<p>Increase in soil fertility (D)</p> Signup and view all the answers

What process can help mitigate the effects of acid rain on the environment?

<p>Forestation (D)</p> Signup and view all the answers

What is the primary purpose of fuel desulphurization?

<p>To reduce the sulfur content in fuels (B)</p> Signup and view all the answers

Which of the following is a method used in source control for SO2 emissions?

<p>Fuel modification (B)</p> Signup and view all the answers

What is the highest temperature used in the catalytic step of the Claus process?

<p>1000 - 1400°C (B)</p> Signup and view all the answers

What is the pH of a solution if the hydrogen ion concentration is $1 imes 10^{-4}$ M?

<p>4 (C)</p> Signup and view all the answers

What is the primary byproduct of the thermal step in the Claus process?

<p>Elemental Sulfur (S) (C)</p> Signup and view all the answers

Which of the following has the highest emissions of sulfur dioxide per billion Btu of energy input?

<p>Coal (C)</p> Signup and view all the answers

What is the purpose of removing sulfur between stages in the Claus process?

<p>To achieve a higher conversion rate (B)</p> Signup and view all the answers

How much sulfur is produced in the catalytic step of the Claus process, given the reaction?

<p>2 moles of sulfur (D)</p> Signup and view all the answers

Which compound is formed when sulfur dioxide reacts with oxygen?

<p>SO3 (C)</p> Signup and view all the answers

Which sulfur concentration indicates a need for SO2 removal from waste gases?

<blockquote> <p>4% (D)</p> </blockquote> Signup and view all the answers

What is one of the roles of hydrocarbons in hydrodesulfurization?

<p>To facilitate the conversion of sulfur to H2S (B)</p> Signup and view all the answers

How much sulfur dioxide (SO2) is generated per year during copper production from CuFeS2?

<p>6.1 x 10^8 kg/yr (D)</p> Signup and view all the answers

What is the approximate conversion rate of SO2 in a single absorption process?

<p>~98% (C)</p> Signup and view all the answers

What is the molecular weight of sulfuric acid (H2SO4)?

<p>98 g/mol (B)</p> Signup and view all the answers

What is flue gas desulphurization primarily used for?

<p>To remove SO2 from rich waste gases (B)</p> Signup and view all the answers

What reaction occurs to convert SO2 into H2SO4?

<p>SO3 + H2O → H2SO4 (A), SO2 + ½ O2 → SO3 (C)</p> Signup and view all the answers

Which of the following pollutants has the lowest emission level when comparing natural gas, oil, and coal?

<p>Mercury (D)</p> Signup and view all the answers

When smelting chalcopyrite (CuFeS2), what is one of the key emissions produced?

<p>Sulfur Dioxide (D)</p> Signup and view all the answers

What is the primary purpose of flue gas desulfurization (FGD)?

<p>Remove sulfur dioxide from waste gases (B)</p> Signup and view all the answers

What is the primary goal of the Claus process?

<p>To convert hydrogen sulfide to sulfur (A)</p> Signup and view all the answers

Which of the following processes is NOT mentioned as a method for SO2 removal from waste gases?

<p>Biological oxidation (C)</p> Signup and view all the answers

Which nitrogen oxide is predominant in combustion processes?

<p>Nitric oxide (NO) (B)</p> Signup and view all the answers

What is the common term for the mixture of nitric oxide and nitrogen dioxide?

<p>NOx (B)</p> Signup and view all the answers

Which of the following nitrogen oxides is NOT mentioned as present in significant amounts in the atmosphere?

<p>Nitrogen pentoxide (N2O5) (D)</p> Signup and view all the answers

What is the 16th most abundant element in the atmosphere, as mentioned?

<p>Sulfur (A)</p> Signup and view all the answers

What reaction results in the formation of nitrogen dioxide (NO2)?

<p>NO + O2 (C)</p> Signup and view all the answers

What is the primary compound used in the Limestone Wet Scrubbing process for SO2 removal?

<p>Calcium Carbonate (B)</p> Signup and view all the answers

Which of the following is a significant operational problem associated with limestone wet scrubbing?

<p>Poor solid-liquid separation (A)</p> Signup and view all the answers

What is one of the advantages of using lime instead of limestone in the wet scrubbing process?

<p>Higher chemical reactivity (B)</p> Signup and view all the answers

What is the major disadvantage of lime scrubbing compared to limestone scrubbing?

<p>Higher cost of lime (C)</p> Signup and view all the answers

What is formed as a byproduct when limestone reacts with SO2 in the wet scrubbing process?

<p>Calcium Sulfate (A)</p> Signup and view all the answers

Why is the Dual Alkali process utilized for SO2 removal?

<p>To provide a solution to scaling issues (D)</p> Signup and view all the answers

What is the efficiency range of the Limestone Wet Scrubbing process in terms of SO2 removal?

<p>80-95% (A)</p> Signup and view all the answers

Which reaction represents the initial step of the limestone wet scrubbing process?

<p>2 CaCO3 + H2O + 2SO2 → 2 CaSO3 + 2CO2 + H2O (D)</p> Signup and view all the answers

Flashcards

Smelting Reaction

A chemical process of extracting metal from its ore, using heat. In this case, copper and iron are extracted from copper iron sulfide.

SO2 Emissions

Sulfur dioxide released into the atmosphere, primarily from industrial processes like smelting.

Acid Rain Formation

Rain with a lower pH than normal, caused by atmospheric pollution containing sulfur dioxide (SO2) and nitrogen oxides (NOx) reacting with water.

SO2 + Water reaction

Sulfur dioxide reacts with water and oxygen to form sulfuric acid (H2SO4).

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Acid Rain Impacts - Health

Acid rain can cause respiratory problems and heart diseases.

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Acid Rain Impacts - Environment

Acid rain damages vegetation, corrodes metals and building materials, and reduces visibility.

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Acid Rain Impacts - Aquatic Environment

Acidification of water bodies harms aquatic life and reproduction.

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Acid Rain Impacts - Crops

Acid rain leaches nutrients from the soil, reducing crop productivity.

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Normal Rainwater pH

The typical pH of rainwater, approximately 5.6, resulting from dissolved carbon dioxide from the atmosphere.

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Acid Rain Damage Quantification

Measuring the impact of acid rain on the pH of soil or water.

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Nitrogen Oxides (NOx)

A mixture of nitric oxide (NO) and nitrogen dioxide (NO2).

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Nitric Oxide (NO)

A colorless gas; a major nitrogen oxide pollutant.

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Nitrogen Dioxide (NO2)

A nitrogen oxide, often associated with NO.

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Nitrogen Oxide Sources

Combustion processes generate most nitrogen oxides, mainly NO.

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Forms of Nitrogen Oxides

Different forms exist, including Nitric oxide (NO), Nitrogen dioxide (NO2), Nitrous oxide (N2O), and more.

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Claus Process

A method for converting hydrogen sulfide (H2S) into elemental sulfur (S).

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H2S Treatment (Claus Process)

Converts H2S gas to sulfur through thermal and catalytic steps, aiming for high sulfur yield.

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Partial Oxidation of H2S

Converting a fraction of H2S into sulfur and SO2 using oxygen at specific temperatures.

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SO2 Removal

A process to remove SO2 gas from industrial emissions.

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Copper Ore Smelting

Extraction of copper from chalcopyrite (CuFeS2), often producing SO2 as a byproduct.

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SO2 Conversion

Conversion of SO2 into sulfuric acid (H2SO4) through oxidation and reaction with water.

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SOx/NOx Emission Amount

The quantity of sulfur oxides (SOx) and nitrogen oxides (NOx) released into the atmosphere.

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Acid Rain Transfer

The amount of SOx/NOx emissions that are carried to the ground by precipitation (rain).

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Hydrogen Ion Concentration ([H+])

The level of acidity in a solution, measured by the concentration of hydrogen ions.

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Acid Rain Area/Volume

The geographic region and amount of damage caused by acid rain.

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Fuel Substitution

Replacing a fuel source (like coal) with a cleaner one (like natural gas) to reduce emissions.

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Fuel Desulfurization

Removing sulfur compounds from fuels to decrease SOx emissions.

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Hydrodesulfurization (HDS)

A process used to remove sulfur from fuels by converting sulfur to H2S.

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Flue Gas Desulfurization (FGD)

A method of removing SO2 from exhaust gas (often from power plants).

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Fossil Fuel Emission Levels

The amount of pollutants released per unit of energy generated from different fossil fuels (coal, oil, natural gas).

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Fuel Modification

Changing existing fuels to make them cleaner, e.g. transforming coal into syngas.

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Molecular Weight of SO2

The total mass of one mole of sulfur dioxide (SO2) molecules, calculated by adding the atomic weights of the constituent atoms. It's 64 grams per mole.

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Molecular Weight of H2SO4

The total mass of one mole of sulfuric acid (H2SO4) molecules, determined by calculating the sum of the atomic weights of its constituent atoms and is 98 grams per mole.

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Molecular Weight of CuFeS2

The sum of the atomic weights of copper (Cu), iron (Fe), and sulfur (S) in one mole of copper iron sulfide (CuFeS2) and is 183 grams per mole.

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Smelting Reaction

A chemical process that extracts a metal from its ore using heat.

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SO2 Production from Smelting

A specific smelting process creates copper (Cu) by producing sulfur dioxide (SO2), in the ratio of 4 mols SO2 for 2 mols Cu.

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SO2 to H2SO4 conversion

The process changing sulfur dioxide into sulfuric acid, with a catalyst.

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Flue Gas Desulphurization (FGD)

A method to remove SO2 pollution from industrial waste gases - using wet scrubbing is one method.

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Limestone Wet Scrubbing

A process in FGD using limestone to absorb SO2 from industrial waste gas.

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Limestone Wet Scrubbing

A process for removing sulfur dioxide (SO2) from gas by injecting limestone (CaCO3) into water to form a slurry and react with the SO2.

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SO2 Removal Efficiency (Limestone)

The percentage of SO2 removed by a limestone wet scrubbing process, typically ranging from 80-95%.

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Solid Waste from Limestone

A significant amount of solid waste is generated in limestone scrubbing, largely composed of calcium sulfate.

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Limestone Chemical Reaction

The chemical reaction in which limestone (CaCO3), water (H2O) and sulfur dioxide (SO2) react to form calcium sulfite (CaSO3) and carbon dioxide (CO2).

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CaSO3 Oxidation

Calcium sulfite (CaSO3) can further oxidize to calcium sulfate (CaSO4).

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Lime Wet Scrubbing

A method of SO2 removal similar to limestone scrubbing, but using lime (CaO) instead of limestone.

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Lime Chemical Reactivity

Ca(OH)2 (hydrated lime) is more chemically reactive than CaCO3 (limestone), leading to potentially better SO2 removal utilization.

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Dual Alkali Processes

A technique using both lime and limestone to remove SO2, minimizing scaling and plugging issues typical of single-reagent systems.

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Corrosion (Scrubbing)

The deterioration of materials due to corrosive compounds in flue gas (like chlorides) during sulfur dioxide removal and other processes.

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Study Notes

Air Pollution Control Engineering - Week 12

  • Oxides of sulfur and nitrogen are discussed, along with their characteristics and control methods.
  • A quiz on topics 8-12 is scheduled for November 15, 2024, at 9:30 AM.
  • The quiz will consist of 25 multiple-choice questions and will last 50 minutes.
  • A calculator is required for the quiz.
  • Feedback on the teaching materials will be available online starting November 10, 2024.

Oxides of Sulfur - Characteristics and Control

  • Sulfur compounds:

    • Sulfur dioxide (SOâ‚‚) is a major component (98%).
    • Sulfur trioxide (SO3) is a minor component (2%).
    • SOx represents these gases.

  • Source control:

    • The primary source of SOâ‚‚ is the combustion of sulfur-containing fuels, such as coal and oil

  • Fuel substitution: Switching to cleaner fuels, such as natural gas, to reduce sulfur emissions.

  • Fuel desulfurization: Reducing sulfur content in existing fuels.

  • Fuel modification: Modifying fuel to make it cleaner.

  • Tailpipe control:

    • Removing SO2 from the waste gas by absorption to create sulfuric acid for rich waste gases (concentration > 4%).
    • SO2 removal from lean waste gases (concentration <4%) uses flue gas desulfurization (FGD).

Oxides of Nitrogen - Characteristics and Control

  • Nitrogen compounds: Oxidation-reduction processes.
  • Similarity and differences with SOx: Both form acid rain precursors.
  • Formation of NOx:
  • Thermal NOx (formed at high combustion temperatures)
  • Prompt NOx (formed in the presence of hydrocarbons)
  • Fuel NOx (formed during the combustion of fuels containing nitrogen).
  • Control methods:
  • Source control (substituting or modifying fuels)
  • Process control (modifying combustion conditions)
  • Tailpipe control

SOx (Sulphur Dioxide)

  • Forms of Sulfur Oxides: Significant amounts are Sulfur monoxide (SO), sulfur dioxide (SOâ‚‚), sulfur trioxide (SO₃), sulfur tetroxide (SOâ‚„), sulfur sesquioxide (Sâ‚‚O₃), and sulfur heptoxide (Sâ‚‚O₇). SOâ‚‚ is the significant one, and SOx is the mixture of SOâ‚‚ and SO₃.
  • Sulfur (S): The 16th most abundant element on Earth's crust, often found as Gypsum (CaSOâ‚„.2Hâ‚‚O), which is slightly soluble in water.
  • SOâ‚‚ and SO₃ Formation: SOâ‚‚ can oxidize to SO₃ at high temperatures. SO2 is moderately soluble in water and aqueous liquids, facilitating its removal using wet scrubbers. 50:1 SOâ‚‚ : SO₃ ratio.
  • Anthropogenic Sources: Combustion of sulfur-containing fuels, industrial processes (smelting and petrochemical).
  • Natural Sources: Natural decay of organic matter, volcanoes
  • Impacts of SOâ‚‚ Emissions:
    • Health impacts: respiratory diseases, heart disease.
    • Environmental impacts: acid rain, reduction in visibility (sulphurous smog), injury to vegetation, metal corrosion, attack on building materials.
    • Reactions: 2SOâ‚‚ + 2Hâ‚‚O + Oâ‚‚ →2Hâ‚‚SOâ‚„ (acid rain formation)

Acid Rain

  • Formation of acids SOx and NOx.
  • Impacts on environment and aquatic life
  • Example of reacting with limestone CaCO3+ H2SO4 → CaSO4 + COâ‚‚ + Hâ‚‚O.

Nitrogen

  • Most nitrogen is in atmospheric inert gas form. Comparatively low concentration in rocks. Reduction and oxidation states of nitrogen.

  • Forms of Nitrogen Oxides: Nitric oxide (NO), Nitrogen dioxide (NO2), Nitrous oxide (N2O), Nitrogen trioxide (N2O3), and Nitrogen pentoxide (N2O5). NO is the mixture of NO and NO2.

  • Major Nitrogen Oxide Pollutants:

    • NO (colorless, prone to oxidize to NO2, a precursor to ozone and photochemical smog)
    • NO2 (reddish-brown gas, harms respiratory system, leads to photochemical smog)
    • N2O (laughing gas, greenhouse gas, ozone layer destroyer, anesthetic)

  • Sources of NOX: Motor vehicles, combustion processes (coal and oil), industrial processes (chemical and metal processing), and natural sources (lightning strikes, volcanoes).

  • Impacts of NOX Emissions:

    • Health impacts: respiratory diseases.
    • Environmental impacts: acid rain, damages to trees/lakes, ozone formation (smog), air pollution, and wide-spread pollution.

  • Reactions: NO + 0.5Oâ‚‚ → NO2

  • Similarities with SOx: Both NOx and SOx form acids and are precursors to acid rain, significant formation of particles , and cause respiratory problems at high doses; both largely emitted from combustion.

  • Differences with SOx: Motor vehicles are largely responsible for NOx emissions; N content in fuel affects NOx emissions more compared to SOx. NOx emissions more susceptible to altering combustion conditions.

  • Chemical reactions of forming NOx. Equilibrium constant changes with temperature. Lower temperatures are favorable for NO2, while higher temperatures favor NO.

  • Formation of NOx: Thermal NOx, Prompt NOx, Fuel NOx

  • Control of NOx: Source control (substituting or modifying fuels)

  • Combustion Modification (reducing combustion temperature, residence time or oxygen concentration).

  • Add-on controls (SNCR & SCR selective catalytic reduction).

  • Control of SO2 and NOx emissions: Fuel substitution (switching fuel types), Fuel modification(changing fuel composition), and Tailpipe/Process control (Removing SO2 from gases/Modifying combustion conditions), Add-on controls/treatment (e.g., using scrubbers or catalytic converters)

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EN3004 Air Pollution Control Engineering Lecture 12 PDF

Description

This quiz covers topics 8-12 in Air Pollution Control Engineering, focusing on oxides of sulfur and nitrogen, their characteristics, and control methods. The assessment includes 25 multiple-choice questions and is scheduled for November 15, 2024. A calculator is required during the quiz for calculations related to pollution control.

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