Example of a Prime Mover?
A steam turbine
Large power production plants tend to be of the thermal type because they can burn solid fuels and...
The heat cycle they use is the most efficient
A steam engine will have the steam supply to the cylinder shut off once the piston has travelled...
25-35% of its stroke. (1/4-1/3)
Where is reciprocating motion converted to rotary motion in a Steam engine?
At the crankshaft
The Crosshead is where...
Linear motion becomes angular motion
A steam engine piston...
Moves fastest at the beginning of the stroke.
A routine inspection of an operating steam engine should cover first and foremost..
Lubricators
Whenever feasibly possible, when checking bearings on running pieces of equipment it is wise to..
Get accustomed to normal running temperatures and vibration by feel
One of the first ways to detect a fault in a reciprocating engine is..
by sound
Purpose of the D slide Valve?
Admit and Exhaust steam into the cylinders
A steam turbine's exhaust can often supply a process with steam because?
it is free of oil
The exhaust steam from a steam turbine is more acceptable for process than the exhaust from a steam engine because?
It is free of oil
The exhaust steam from a condensing steam turbine ____________ than the exhaust from a steam engine
Has more moisture
Steam turbine Bearings?
Split sleeves and Oil rings with a precision bored high grade babbitt.
Turbines often have segmental carbon ring sealing glands which are held in place by....
Garter Springs
Steam Turbine Blades?
- All made of rolled and drawn stainless steel
- Held in machined slots in the wheel rim by drive screws
To confine steam to the blade and stiffen the blades against vibration is...
Shrouding
A steam turbine should trip or shut down when normal operating speed is exceeded by...
10-15%
Turbine Governors?
Hydraulically Operated and directly driven by the turbine shaft and mechanically sensing
Condensing Turbines will have a vacuum in the last row of rotating blades. True or False?
True
Turbine Overspeed Trips:
- Prevents turbine from excessive speed
- Uses a spring loaded pin
- Will close the steam stop valve
- Should be tested before put into service
Overspeed trips are installed on ALL turbines. True or False?
True
Turbine lube oil can be used to Operate the Turbine Governor. True or False?
True.
The purpose of turbine glands is to
prevent..
Steam from entering the lubrication system
Shaft sealing in high output turbines is done with..
Labyrinth Glands
When the steam pressure drop occurs in only the stationary members or components of a turbine, the turbine is known as..
An impulse unit
A large reaction turbine will have...
steam pressure dropping in only the moving sections
Turbine speed can be "fine tuned" with a device which will be limited to about 10% over the rated speed. This device is the..
Hand Speed control
Shaft sealing carbon glands are self lubricating. True or False?
True.
The great majority of steam turbine governing systems utilize the..
Mechanical Centrifugal Type
Where is the pressure drop in reaction Turbines?
Stationary and Rotating blades
Where does velocity decrease in a reaction turbine?
In the fixed blading
In an impulse turbine, where is the steam pressure reduced?
In the nozzles
When starting a steam turbine it is customary practice to...
turn on all cooling water systems first
The average amount of water that evaporates from a cooling tower?
5% of water
Places where natural draft cooling towers function most efficiently?
- Large open spaces and where wind is relatively constant
Excessive wind velocity can be caused by what in Natural draft cooling towers?
Broken louvres, excessive water pressure or excessive water drift
Compared to a crossflow tower, a counterflow tower...
Requires less floor space
Water contained in the airstream at the discharge of a cooling tower is removed with...
Drift eliminators
A cooling tower which requires neither fan nor fill is the...
Venturi Tower
A valve which prevents water flow over the fill of a tower during cold weather should not be closed until the temperature reaches...?
+ 27 deg.c
To prevent cooling tower basin water from freezing during cold weather many units are equipped with what?
Electric basin heaters
Why is scaling not as bad in cooling towers as boilers?
Temperature is way lower
Gas turbines use what kinds of compressors?
Rotating AXIAL type compressors
Many typical steam plant auxiliaries are eliminated with a gas turbine due to its...?
High power to weight ratio
Gas turbines are very popular where...
Noise does not present a problem
Gas turbines are popular when considering...
Emergency power generation
A two shaft gas turbine...
has the load turbine downstream from the compressor turbine
Rotational speed before a gas turbine may be ignited?
20-30% of its maximum speed
Early gas turbines were handicapped by what?
Metals not standing the high temperatures involved
The temperature in which the air can be raised at the turbine inlet is an indication of the units what?
Its efficiency
The output power of a gas turbine is directly related to the what?
Mass of gas passing through the turbine per second
The low installation cost of a gas turbine is due to what?
Because less auxiliary equipment is needed
3 advantages that make gas turbines better than other prime movers?
- Minimum cooling water required
- Low maintenance
- Rapid start up and loading
A gas turbine performs most effectively with what?
A low ambient air temperature
A combined steam and gas turbine arrangement can be termed...?
A cogeneration system
The purpose of a regenerator is what?
To recirculate some of the exhaust gases back through the compressor
Impulse turbines:
- have a velocity increase through the nozzles
- have the same blade angles on inlet and outlet blades
- could have more than one set of blades
- may not require a thrust bearing
Impulse turbines have no pressure drop through the moving blades. True or False?
True
What are Dummy Pistons used for?
- Usually installed on reaction turbines only
- Usually installed on the high pressure end of the turbine
- Balance out the thrust on the rotor
Cooling towers:
- Remove heat from the condensate
- Should use water treatment
Steam turbine blades are made of?
Stainless steel
Which valves should be open when starting a RECIPROCATING pump?
Inlet and OUTLET
What size of packing should be used to repack a pump gland having an 8.6 cm stuffing box bore and 6.7 cm pump shaft diameter?
.95 ( 1.9/2 = .95)
Sliding vane pump is of what type?
Rotary type
Greases are commonly a mixture of what 2 substances?
Mineral Oils and Soap
Causes of anti-friction bearing failures are???
- Improper fitting
- False Brinelling
- High Operating temperature
- Poor Quality lubricant
Pour Point?
Lowest temperature which oil will flow
How is a Voltmeter properly placed?
In parallel with the circuit
10 metres of wire of uniform cross sectional area has a resistance of 20 ohms. If the length of the wire is increased to 500 metres the resistance will be...?
- 1000 Ohms
500m/10m X 20 Ohms = 1000 Ohms
Regarding alternating current systems, starting from zero and rising to a maximum positive or negative value and returning to zero, is known as...?
One half cycle *
The rotating field of an AC alternator is obtained by exciting the windings on the rotor with what?
DC power
Commutators are found in?
DC generators
The Bourdon Tube is often shaped in the form of a "C" and has an arc length of about...?
270 degrees
In a variable area flow meter the differential pressure is....
Is Contant
The low water cut off can be tested by....
Shutting off the feedwater
Your boiler is operated with automatic water feeders. If the boiler suddenly requires an increase in water treatment, what should you look for?
A loss of water
The blow down valve of a steam heating boiler must be installed where?
At the lowest point of the boiler
Steam is prevented from leaking out around the valve stem of a packless radiator valve with the use of a what?
A diaphragm
2 element FW control?
Measures Drum level and Steam flow
One advantage of the electric probe type of low water fuel cut-off is what?
- Contains no moving parts
- The possibility of mechanical failure is eliminated
In some installations in order to guarantee a supply of clear hot water and prolong the life of a hot water heater, what is done to the inner shell?
The inner shell is lined with cement
Where should safety valves be fitted on a Refrigeration System?
On the receiver
3 most common compressors in Refrigeration systems?
- Axial, Rotary and Reciprocating
NOT Centrifugal
3 most common elements used on Humidistats?
Human Hair, Hygroscopic Materials and Wood
A Runaround air conditioning heat recovery system consists of two finned tube heat exchangers, the preconditioning coil and the recovery coil. Where is the preconditioning coil of this system usually located?
In the duct work handling the ventilation into the process
The best type of filter for the removal of fine dust, smoke and fumes is...
The electrostatic precipitator
The purpose of boiling out a boiler is...
To remove any grease and oil from the heating surface
The boiling out procedure should be done at what specific time?
When the boiler is at half operating pressure
Prior to commencing boiler cleaning operations it is necessary to do what 2 things?
- Close steam and water valves
- Tag all valves to indicate shut down
Natural ropes are made of what material?
Manila
Raising or lowering of heavy objects using ropes and cables is known as what?
Hoisting
The purpose of the absorber in a natural gas plant is to...
Remove Hydrogen sulphide and carbon dioxide from the gas
Where is the Economizer located in the steam system of an Electricity generating plant?
Between the feedwater pumps and the boiler drum
What is eliminated while burning black liquor in a Recovery boiler?
The lignin
In a compression ignition engine the fuel is ignited by...
- The compression ignition temperature
- Between 540-650 deg.C and 2800-4200 kPa
Removal of exhaust gases in a Diesel Engine?
Scavenging
How is diesel engine governing accomplished?
varying the fuel quantity
Four stroke cycle engine valves are operated by what?
Cams
An engine which develops one power stroke with every other turn of the crankshaft is the...?
Four stroke gas engine
Compression ignition engines compress air at what time?
On the compression stroke
Compression ignition engines inject fuel by the use of what?
Camshafts
MOST diesel engines are ignited by what?
Compression in the cylinder
What kind of diesel engines would use a starting motor or a handcrank?
Smaller diesel engines
Compressed air is delivered to each cylinder at what pressure while starting diesel engines?
2100 kPa approximately
The capacity of a centrifugal pump....?
Varies with discharge pressure
Centrifugal pump power requirements are decreased when...
The litres moved per minute is DECREASED
A double acting pump is what kind of pump?
A positive displacement pump
2 characteristics of a DIFFUSER pump?
- Stationary guide vanes surrounding the impeller
- Has a higher efficiency than a volute type
2 characteristics of turbine pumps?
- High pressure pumps
- The liquid gains energy in a number of pulses
Cavitation refers to what?
When a pump is filled with vapour
If a pump is cavitating what can you do to prevent
or reduce the cavitation?
You can raise the suction pressure
Pumps handling cryogenic materials run at.....?
Really low temperatures
Turbine pumps are best suited for what types of applications?
Low capacity, High pressure service
Pump wear rings are installed on an impeller by set screws,
threading or.......??
Shrinking
Common wear ring materials?
Bronze or cast iron
Wearing rings?
- Used on impellers and the casing
- Reduce maintenance costs
Compression type packing?
- Reduces maintenance costs
- Prevents air from entering the pump
Lantern rings:
- Fed by a liquid
- Prevent air from entering the pump
- Mostly used on high lift pumps
If a stuffing box is to prevent the entrance of air, it is equipped with what?
A sealing cage
If a mechanical seal leaks, which direction will it leak?
Radial to the shaft
The part of a mechanical seal which prevents axial leakage is?
The O ring
Common cause of shaft misalignment?
Shaft FLEXING
Important thing to check when a pump is operating?
Check that there is discharge pressure
Symptom of a plugged impeller?
No liquid being delivered
Most likely place to find compressed air machinery?
Coal mines
n a centrifugal compressor the kinetic energy is converted to potential energy in the..?
Volute, Diffuser or both.
single stage air compressors can have 2 cylinders. true or false?
True.
What type of unit uses a belt driven lubricator?
The sliding vane unit
High gearing is used on what types of compressors?
Screw type compressors
Valves on a reciprocating compressor are opened by...?
A pressure difference
Anti friction base greases?
Barium and Lithium base greases
Cheapest, most common grease?
Calcium based
Property of a lubricant which portrays its ability to support a load?
Its viscosity
Where are the grooves in large Journal bearings?
In the non pressure area
The collar type bearing does not utilize what?
The oil wedge principle
A journal bearing supports a ______ .
Shaft
An anti friction bearing can be a thrust bearing. True or False?
True.
When replacing/removing anti friction ball bearings, what shouldnt you do?
Transmit force directly on the ball bearings