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</p> Signup and view all the answers

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

    <p>Forestation</p> Signup and view all the answers

    What is the primary purpose of fuel desulphurization?

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

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

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

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

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

    Which compound is formed when sulfur dioxide reacts with oxygen?

    <p>SO3</p> Signup and view all the answers

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

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

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

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

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

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

    What is flue gas desulphurization primarily used for?

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

    What reaction occurs to convert SO2 into H2SO4?

    <p>SO3 + H2O → H2SO4</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</p> Signup and view all the answers

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

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

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

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

    What is the primary goal of the Claus process?

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

    Which nitrogen oxide is predominant in combustion processes?

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

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

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

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

    <p>Sulfur</p> Signup and view all the answers

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

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

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

    <p>Higher cost of lime</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</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</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%</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</p> Signup and view all the answers

    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 (SO₂) is a major component (98%).
      • Sulfur trioxide (SO3) is a minor component (2%).
      • SOx represents these gases.

    • Source control:

      • The primary source of SO₂ 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 (SO₂), sulfur trioxide (SO₃), sulfur tetroxide (SO₄), sulfur sesquioxide (S₂O₃), and sulfur heptoxide (S₂O₇). SO₂ is the significant one, and SOx is the mixture of SO₂ and SO₃.
    • Sulfur (S): The 16th most abundant element on Earth's crust, often found as Gypsum (CaSO₄.2H₂O), which is slightly soluble in water.
    • SO₂ and SO₃ Formation: SO₂ can oxidize to SO₃ at high temperatures. SO2 is moderately soluble in water and aqueous liquids, facilitating its removal using wet scrubbers. 50:1 SO₂ : SO₃ ratio.
    • Anthropogenic Sources: Combustion of sulfur-containing fuels, industrial processes (smelting and petrochemical).
    • Natural Sources: Natural decay of organic matter, volcanoes
    • Impacts of SO₂ 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: 2SO₂ + 2H₂O + O₂ →2H₂SO₄ (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 + CO₂ + H₂O.

    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 + 0.5O₂ → 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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