Deck 5: Compressors

Question 1

Lobe compressors can be used in wet and dry gas service.

Answer 1

True

Question 2

The suction and the discharge ports on a liquid ring compressor are located:

A) on the rotor
B) on the inlet and outlet side of the casing
C) suction on rotor, discharge on casing
D) discharge on rotor and suction on casing

Answer 2

on the rotor

Question 3

Liquid ring compressors are primarily used in:

A) hazardous gases
B) toxic gases
C) hot gases and vapors
D) solvent recovery
E) all the above

Answer 3

all the above

Question 4

Select the main components of a liquid ring compressor.

A) casing
B) large discharge port
C) impeller
D) large suction port
E) small discharge port
F) small suction port
G) inlet guide vanes
H) rotor
I) curved vanes
J) intercooler
K) piston rod
L) air cavity
M) water or seal liquid
N) suction eye

Question 5

Select the basic parts of an axial compressor:

Question 6

Describe two types of compressor layouts.

A) diffuser and stator
B) V and L
C) open and closed
D) parallel and multistage

Question 7

Select the basic parts of a cylinder and piston reciprocating compressor:

Question 8

If a lobe compressor is used for wet gas service the _________ rotation is recommended.

A) upward
B) downward
C) is not used for wet gas service
D) a or b is OK

Question 9

Lobe compressors can be utilized as vacuum units.

Question 10

The most common type of reciprocating compressor is:

A) plunger
B) rotary screw
C) piston
D) diaphragm

Question 11

Parallel cylinder arrangement occurs when:

A) one cylinder is lined up with two separate intakes and common discharge lines.
B) two cylinders are lined up with separate intakes and common discharge lines.
C) two cylinders are lined up with common intakes and separate discharge lines.
D) two cylinders are lined up with separate intakes and separate discharge lines.

Question 12

What two items make up a stage in an axial compressor?

A) stator and rotor blade
B) diffuser and impeller
C) impeller and casing
D) piston and rings

Question 13

Piston and cylinder lubrication is more important in:

A) safety design than actual application
B) c & d
C) a pump
D) a compressor

Question 14

The higher the pressure the larger the volume.

Question 15

Liquids compress as easily as vapors or gases.

Question 16

Compressed gases will resume _______________ when released:

A) 50 % original volume
B) 71% original volume
C) 98% original volume
D) 100 % original volume

Question 17

The principle of compression has a measurable relationship between the volume a set weight of gas occupies.

Question 18

Compressors are primarily designed to:

A) compress gases and small amounts of liquid
B) compress relatively dry gases
C) compress hot fluids
D) work in closed systems

Question 19

An inlet valve unloader is:

A) a safety valve designed to prevent over pressuring the receiver.
B) a relief valve designed to prevent over pressuring the receiver.
C) term applied to gas movement between stages
D) a & b

Question 20

A demister is:

A) a cyclone type device used to remove solids from gas
B) a cyclone type device used to remove moisture from gas
C) converts liquid into mist
D) a heat exchanger

Question 21

A desiccant dryer is used to remove moisture from compressor gases as they are passed over a chemical called desiccant.

Question 22

The design and operation of a compressor can usually be classified into two groups:

A) positive displacement and dynamic
B) rotary and reciprocating
C) axial and centrifugal
D) piston and centrifugal

Question 23

Select the major components of a sliding vane compressor:

A) off center rotor
B) direct center rotor
C) crankshaft
D) discharge port
E) vanes
F) diffuser plates
G) air cooled jacket
H) connecting rod
I) impellers
J) piston
K) suction port
L) impellers.
M) casing and base
N) cooling water jacket
O) .....
P) cylinder

Question 24

Centrifugal compressors operate by:

A) compressing the gases in a cylinder and releasing
B) accelerating the gas axially along the shaft
C) accelerating the gas and converting the energy to pressure
D) a & c

Question 25

The type of compressor that uses two helical rotors to compress gases:

A) twin lobe design
B) liquid ring
C) rotary screw
D) piston- V layout

Question 26

The internal lobes on a lobe compressor are designed:

A) not to touch
B) with a power lobe that pushes the idler lobe
C) with a few thousandths of an inch clearance between casing and lobes.
D) a & c

Question 27

The stator blades in axial compressor can be arranged in all the following designs except:

A) fixed
B) individually adjustable
C) stator-rotor impeller
D) continually variable

Question 28

A 23,000 horse power axial compressor produces as efficiently as a comparable _________ horse power centrifugal compressor.

A) 30,000
B) 20,000
C) 25,000
D) 23,000

Question 29

The typical compressor system most closely resembles the following:

A) compressor, dryer, air receiver, gas header
B) compressor, air receiver, dryer, gas header
C) compressor, gas header, air receiver, dryer
D) gas header, compressor, dryer, air receiver

Question 30

List two dynamic compressors:

A) dynamic & rotary
B) rotary & reciprocating
C) centrifugal & axial
D) axial & centronic

Question 31

Gas volume does not vary with temperature and pressure.

Question 32

Liquids are considered to be:

A) non-compressible
B) compressible in low pressure operations
C) compressible during high pressure operations <500 psig
D) compressible in a PD compressor operation

Question 33

What type of equipment is an aftercooler or intercooler?

A) air cooled heat exchanger
B) water cooled heat exchanger
C) refrigeration expansion valve
D) a or b

Question 34

Gases and vapors are non-compressible.

A) true
B) false
C) depends on molecular structure of gas or vapor
D) directly proportional to temperature

Question 35

The rapid compression of a gas or vapor:

A) moves molecules closer together
B) generates heat
C) produces a cooling effect
D) a & b
E) a & c

Question 36

Compressed gases produce heat because of molecular friction.

Question 37

In a sliding vane compressor the gas inlet port is positioned so gas flows into the vanes when they are:

A) fully extended and the largest air pocket is formed
B) 50% extended and the air pocket is half formed
C) 25% extended and the air pocket is just forming
D) the vanes are always fully extended on a sliding vane compressor because the rotor is positioned "direct center."

Question 38

Lobe compressors are characterized by the:

A) close clearances between the casing and impellers
B) two kidney bean shaped impellers
C) use of timing gears
D) all the above

Question 39

If the compression ratio for a 3 stage compressor is 3.2. What is the final pressure?

A) 481.7 psia
B) 212.3 psig
C) 67.4 psia
D) 180.5 psia

Question 40

If the compression ratio for a 4 stage compressor is 3.6. What is the final pressure?

A) 850 psia
B) 989 psia
C) 1,890 psig
D) 2,469 psia

Question 41

If the compression ratio for a 6 stage compressor is 4.0. What is the final pressure?

A) 235.2 psia
B) 3,763.2 psia
C) 60211 psia
D) 15,052.8 psia

Question 42

Rotary screw compressors operate at speeds between:

A) 200 and 1000 RPM
B) 425 and 1250 RPM
C) 850 and 1600 RPM
D) 1750 and 3600 RPM

Question 43

A rotary screw compressor has a capacity rating:

A) 4,500 CFM
B) 8,000 CFM
C) 12,000 CFM
D) 16,000 CFM

Question 44

Rotary screw compressors deliver pressures between:

A) 35- 55 psig
B) 65- 90 psia
C) 100- 130 psia
D) 120- 160 psia

Question 45

Reciprocating compressors typical discharge pressure range from:

A) 0- 30,000 psi
B) 0- 20,000 psi
C) 0- 10,000 psi
D) 0- 7,500 psi

Question 46

On a centrifugal compressor the part of the impeller vane that comes into contact with the gas first is called the:

A) wear ring outlet
B) suction eye
C) impeller shroud
D) suction vane tip

Question 47

What is the first step in starting up a compressor:

Question 48

A liquid ring compressor can produce a vacuum of:

A) 12-16 inches of Hg
B) 27- 29 inches of Hg
C) 16- 22 inches of Hg
D) 22- 26 inches of Hg

Question 49

List the devices used in a reciprocating compressor to provide smooth gas flow, reduce vibration, and prevent under/ overloading: