![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Module 6: Air Pollutants and Control Techniques - Halogens - Practice Problems
- Instructions:
- Answer these questions on a sheet of paper and check your responses against those provided below.
-
#1
- Hydrogen chloride is:
- Highly soluble in water
- Weakly soluble in water
- Insoluble in water
- Highly soluble in water
- Answer: a. Highly soluble in water
- Hydrogen chloride is highly soluble in water.
-
#2
- What types of industrial sources can generate hydrogen chloride and hydrogen fluoride pollutant gases?
-
- Answer: Industrial sources for hydrogen chloride and hydrogen fluoride pollutant gases can include chemical reactors, mineral production operations, acid production, electronics industry, ore roasting operations, and combustion and incineration processes.
-
#3
- True or False? Hydrogen fluoride is a strong acid.
- True
- False
- True
-
- Answer: b. False
- Hydrogen fluoride is considered to be a weak acid; while, hydrogen chloride is a strong acid.
Practice Problems
Formation Mechanisms
- Instructions:
- Answer these questions on a sheet of paper and check your responses against those provided below.
-
#1
- What types of air pollution control system(s) can cause the formation
of HCl and HF? Select all that apply.
- Wet scrubbers
- Dry scrubbers
- Thermal oxidizers handling chlorinated or fluorinated organic
compounds
- Catalytic oxidizers handling chlorinated or fluorinated organic
compounds
- Adsorption systems handling chlorinated or fluorinated organic compounds
- Wet scrubbers
-
- Answer:
- Thermal oxidizers handling chlorinated or fluorinated organic compounds
- Catalytic oxidizers handling chlorinated or fluorinated organic compounds
- Both thermal and catalytic oxidizers result in the formation of HCl and/or HF if there are chlorinated or fluorinated materials in the gas stream.
- The operating temperatures of wet scrubbers, dry scrubbers, and adsorption systems are too low to form HCl and HF.
-
#2
- Describe the fate of chloride and fluoride compounds found in waste or fuel being fired in incineration or combustion processes.
-
- Answer: Chloride and fluoride compounds, found in the waste or fuel, form hydrogen chloride and hydrogen fluoride almost immediately upon combustion and these acid gases are released into the gas stream. Very little of the original chloride- and fluoride-containing compounds remain in the bottom ash. These two acid gases remain in the vapor phase and do not participate in heterogeneous nucleation. Small quantities may absorb into water that is on particle surfaces when the gas stream has cooled sufficiently.
Practice Problems
Control Techniques
- Instructions:
- Answer these questions on a sheet of paper and check your responses against those provided below.
-
#1
- What types of control techniques are used for hydrogen fluoride
and hydrogen chloride? Select all that apply.
- Wet scrubbers
- Dry scrubbers
- Fabric filters
- Electrostatic precipitators
- Wet scrubbers
-
- Answer:
- a. Wet scrubbers
- b. Dry scrubbers
- Wet scrubbers and dry scrubbers are two types of control equipment for reducing hydrogen fluoride and hydrogen chloride emissions.
-
#2
- What is the most commonly used type of wet scrubber to control hydrogen chloride and hydrogen fluoride emissions?
-
- Answer: Packed tower scrubbers
- Packed tower scrubbers are the most commonly used type of wet scrubber for controlling hydrogen chloride and hydrogen fluoride emissions.
-
#3
- When dry scrubbing systems are used to remove acid gases, the
removal efficiency for HCl and HF is usually ____________ the removal
efficiency for sulfur dioxide.
- Less than
- Greater than
- Approximately the same as
- Less than
-
- Answer: b. Greater than
- When dry scrubbing systems are used to remove acid gases, the removal efficiency for HCl and HF is usually greater than the removal efficiency for sulfur dioxide.