Weeks 4-6 Flashcards

1
Q

How to improve dispersion?

A

-tall stack heights
- intermitten control schemes

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2
Q

Just write out what a mass balance is

A

Accumulation = input - output + net generation

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3
Q

Major Air pollutants for coal-fired plants

A

-Mercury (HG)
- Sulfur dioxide
- nitrogen oxides
- PM
- Trace metals
- VOCs

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4
Q

Catalyst for Air Pollution control

A

-often pellets and honeycomb

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5
Q

Define:
Aerodynamic Diameter

A

-defined as the diameter of a sphere with unit density that has the same settling velocity as the particle of interest

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6
Q

When does Diffusion occur?

A

occurs when small particles happen to diffuse toward the object while passing near it

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7
Q

What is the equation for the average horizontal gas velocity in the chamber mixed or flow

A

V = Q/WH

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8
Q

When does Inertial Impaction occur?

A

occurs when the center of the mass of a particle that is diverging from the fluid streamlines strikes a object

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9
Q

What are gravity settlers

A

a large chamber where contaminated gas passes slowly which allows the particles to settle out via gravity

also refered to as precleaners

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10
Q

What are some advantages of Gravity Settlers

A

-low capital cost
- low energy cost & operating cost
- little maintenance requirements
- dry collection and disposal

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11
Q

What are some disadvantages of Gravity Settlers

A

-low PM collection efficiecy (20-60%)
- doesn’t work with sticky materials
- large physical size
- trays in mult-tray settling chamber may wrap

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12
Q

Collection Efficiency Equation
(Have to memorize this)

A

n= (LgD^2P(part))/ (HVavg(18u))

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13
Q

Collection Efficiency Equation for mixed flow

A

= 1-exp(-n(blockflow)

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14
Q

What are some advantages of Centrifugal Separators

A

-low capital cost
- ability to penetrate at high temps
- ability to collect dry solids as dry materials and liquids as liquids

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15
Q

Equation for Diffusivity

A

D= (kTC)/ (3 pi u* D)

K = boltzman constant
c= cunningham correction factor

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