Dryers Flashcards

1
Q

Name two main types of absorption dryers.

Which on can be regenerated and how?

A

Chemical and liquid dehydration.

Liquid dehydration dryers can be by evaporating the water out if the glycol.

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2
Q

What are the four categories of dryers?

A

Adsorption (physical) (desiccant)

Absorption (chemical) (deliquescent or liquid dehydration)

Refrigeration (coolers)

Mechanical

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3
Q

Can adsorption dryers be regenerated, how?

A

By reversing the flow of hot, dry air through the desiccant bed. 10-15% of dry air is used to regenerate the dryer bed.

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4
Q

What is the lowest dew point a refrigeration dryer can achieve?

A

2-3 degrees Celsius, any lower and the moisture removed may freeze.

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5
Q

How does pressure increase affect the amount if water a sample of air can hold?

A

Pressure increase reduces the volume of the air and reduces the internal spaces moisture molecules can occupy.

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6
Q

How does temperature affect the amount of water a sample of air can hold?

A

A temperature increase increases the volume of air and creates spaces the water molecules can occupy.

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7
Q

List four types commonly used desiccants.

A

Activated alumina

Granulated silica gel (most common)

Bead-type modified silica gel

Molecular sieve

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8
Q

List five mechanical drying methods.

A

Liquid separators

Centrifuge separators

De-mister pads

Over compression

Coalescing filters

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9
Q

List four adverse effect from having moisture in a gas compression system.

A

Corrosion

Contamination

Plugged components

Freezing

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10
Q

As the temperature goes down what happens to the ability of the air to hold moisture?

A

It goes down also.

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11
Q

One pound of water is equal to how many grains?

A

7000 grains is equal to one pound of water.

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12
Q

Out of the four types of dryers, which can achieve a lower dew point than any other?

Absorption, adsorption, refrigeration, and mechanical.

A

Adsorption dryers.

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13
Q

What are three methods of regeneration?

A

Heater less, a portion up to 15% of the dry air is directed back through the desiccant bed of one tower to be regenerated. Oversized compression equipment is required. Dried to a dew point as low as -70 degrees Celsius.

Heater, warm air from an external source pass through and removes moisture.

Removing contaminants, coalescing pre-filters are used to clean the inlet gas. Filter condition is monitored by comparing pressure in to pressure out.

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14
Q

In a deliquescent dryer the air flow is?

Upward through the bed.
Downward through the bed.
Sideways through the bed.
Alternating up and down through the bed.

A

Upward through the bed.

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15
Q

Which type of dryer constantly regenerates itself while in operation?

Rotary (MD)
Desiccant
Deliquescent
Refrigeration

A

Rotary (MD) dryer, separate flows are directed by stationary manifold allowing the moist gas to pass through 75% of the rotor and the hot gas to pass through the remaining 25%.

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16
Q

Regenerated ethylene glycol is typically:

92% pure
94% pure
96% pure
98% pure

A

98% pure, 2% consists of water that was not removed by the still.

17
Q

Liquid dehydration can lower the dew point of a gas _____ from that of the gas entering the dryer.

50-70 C
40-60 C
10-20 C
2-3 C

A

40-60 C