Dryers Flashcards
Name two main types of absorption dryers.
Which on can be regenerated and how?
Chemical and liquid dehydration.
Liquid dehydration dryers can be by evaporating the water out if the glycol.
What are the four categories of dryers?
Adsorption (physical) (desiccant)
Absorption (chemical) (deliquescent or liquid dehydration)
Refrigeration (coolers)
Mechanical
Can adsorption dryers be regenerated, how?
By reversing the flow of hot, dry air through the desiccant bed. 10-15% of dry air is used to regenerate the dryer bed.
What is the lowest dew point a refrigeration dryer can achieve?
2-3 degrees Celsius, any lower and the moisture removed may freeze.
How does pressure increase affect the amount if water a sample of air can hold?
Pressure increase reduces the volume of the air and reduces the internal spaces moisture molecules can occupy.
How does temperature affect the amount of water a sample of air can hold?
A temperature increase increases the volume of air and creates spaces the water molecules can occupy.
List four types commonly used desiccants.
Activated alumina
Granulated silica gel (most common)
Bead-type modified silica gel
Molecular sieve
List five mechanical drying methods.
Liquid separators
Centrifuge separators
De-mister pads
Over compression
Coalescing filters
List four adverse effect from having moisture in a gas compression system.
Corrosion
Contamination
Plugged components
Freezing
As the temperature goes down what happens to the ability of the air to hold moisture?
It goes down also.
One pound of water is equal to how many grains?
7000 grains is equal to one pound of water.
Out of the four types of dryers, which can achieve a lower dew point than any other?
Absorption, adsorption, refrigeration, and mechanical.
Adsorption dryers.
What are three methods of regeneration?
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.
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.
Upward through the bed.
Which type of dryer constantly regenerates itself while in operation?
Rotary (MD)
Desiccant
Deliquescent
Refrigeration
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%.
