Questions Flashcards
1
Q
What is a boiler?
A
A closed vessel that creates steam from heat, under pressure
2
Q
Name two types of boilers
A
Fire tube and water tube
3
Q
What are the advantages of each boiler type
A
Fire tube smaller/more portable but lower pressure. Water tube large and fixed but high pressure
4
Q
What is steam
A
Water in its gaseous state through the application of heat
5
Q
What is the difference between dry and wet steam
A
Wet steam carries more moisture, dry steam is superheated and saturated with heat
6
Q
At what temperature does water boil
A
212 degrees at sea level. This temp increases due to atmospheric pressure
7
Q
What are three methods of heat transfer
A
Radiant - waves from the sun
Conduction- tube metals heating up
Convection- water heating from heated tubes
8
Q
What causes scale and what can result from it?
A
Scale is created by calcium and magnesium in water being left behind when steam is created. Acts as insulator that makes boiled less efficient. Creates hot spots.
9
Q
What is zeolite softener and how does it operate
A
Tiny balls covered in transfer points. With sodium can allow electrical exchange to remove calcium and magnesium as water passes through.
10
Q
What causes hardness in water? What are its effects
A
Hardness is from calcium and magnesium. Creates scaling in boiler and increased TDS
11
Q
What are the problems with high TDS in water? What effect can it have?
A
Total dissolved solids, water heavy with minerals after many cycles. Creates priming and scale, which can damage a boiler
12
Q
Why is a boiler chemically treated?
A
To prevent scale, corrosion, and oxygen pitting
13
Q
Name 3 boiler water tests
A
Alkalinity test - acid absorber, water more resistant to acid
Phosphate test - if using phosphate as scale inhibitors
Sulfite test - if using to negate oxygen
14
Q
How would you run an alkalinity test?
A
With pheno drops and a 25 ml sample of boiler water. Mix with sulfuric acid (50ppm) to test for alkalinity
15
Q
What is a pressure gauge?
A
Measures steam pressure with bourdon tube
16
Q
What is a pig tail?
A
Protects steam gauge from overheating. Pigtail loop catches condensate, which can press against gauge and give a false reading
17
Q
What is absolute pressure? What is gauge pressure?
A
Absolute pressure is gauge pressure plus atmospheric pressure. Gauge pressure has atmospheric pressure already factored in
18
Q
How does a pressure gauge work?
A
Uses a bourdon tube, which is closed at one end. Steam enters the open side and the tube tries to straighten. This movement manipulates the gauge reading.
19
Q
What is a btu
A
British thermal unit. Amount of heat it takes to raise 1 lb of water by 1 degree at 212 degrees
20
Q
What is meant by boiler horsepower?
A
1 boiler horsepower is 34.5 lbs of steam produced in one hour
21
Q
What is draft? What is meant by 1/2 inch of draft?
A
Draft is negative pressure in a boiler furnace. 1/2 inch of draft is .0195 lbs of draft read with a manometer
22
Q
Why would oil in boiler water be dangerous?
A
Causes foaming which can trick out a feed water regulator, leading to low water conditions
23
Q
What is natural draft?
A
Difference in air density. Warm air rises, cooler air fills the void
24
Q
Name 3 types of draft
A
Natural
Forced
Induced
25
Describe the water and boiler steam cycle
Water is treated with zeolite and is stored in make up tank. Travels to deaerator and then to feed pumps. Then to feed regulator and economizer and finally to the drum. Water turns to steam and goes through superheater and then to turbine
26
How does a feed water heater work?
A closed feed water heater has tubes heated by flue gas. No steam contacts the water. Open heaters have steam warming water directly
27
What is a deaerator?
Removed oxygen, heats water. Creates head pressure for feed pumps. Tray type and spray type.
28
What is an air heater?
Heats combustion air. Has a flat surface that turns which is heated by flue gas. Air travels a crossed the other side and warms from the spinning surface
29
What is an economizer and what is it’s purpose?
Preheats water entering the boiler. A secondary feed water heater after a deaerator. Hot flue gas heats tubes to warm water
30
Why is a check valve placed between feed pump and boiler steam drum?
To prevent back feeding the feed pump when it shuts down
31
What is a superheater?
Raises steam temp to temp that doesn’t correspond to its pressure through the application of heat.
32
Name two types of superheater
Pendant style
Direct contact style
33
Define superheated steam
Contains more heat than normal steam while staying at the same pressure
34
What precautions should be taken in regard to a superheater?
Superheater vent must always stay open during start up to prevent damage to tubes, then closed at a certain rate of flow
35
How is heat controlled in a superheater
Controlled by attemperation, injected at primary outlet and secondary inlet.
36
How is feed water controlled to a boiler?
Regulator used in high pressure system
Low water cut off shuts down pumps in low pressure system
37
What grades of fuel oil can be used in a boiler?
6 oil
4 oil
2oil
38
What temp should 6 oil be kept at
90-100 degrees
39
What is a steam trap?
Traps and releases condensate from steam line
40
Name three types of steam trap
Impulse
Bucked
Inverted bucket
41
What is a non return valve and where is it located
Check valve with manual isolation. Prevents steam return when multiple boilers are running. Located at boiler steam outlet
42
What valve is placed between feed pumps and boiler and why?
Check valve, to prevent back feeding water to pumps
43
What is the most important valve on a boiler and why?
Safety valve. Prevents over pressurizing boiler to preserve boiler integrity
44
Name 6 parts of a safety valve
Spring
Seat
Lever
Body
Linkage pin
ID tag
45
What is the operators responsibility in regard to safety valves?
Test valves on a monthly basis, make rounds to look for weeping or leakage. Log all inspections
46
How many safety valves are found on a boiler?
At least 1. If heating surface exceeds 500sqft than it needs an additional valve
47
How often should safety valves be tested
Monthly, certified annually
48
Who is allowed it make adjustments to safety valves?
Only certified individuals
49
What is a safety valve and how does it work?
Valve that goes full open when a certain amount of pressure is applied. Disk is larger than inlet, allows valve to pop open.
50
What can be placed between a safety valve and a boiler?
Nothing
51
What is a water column and where is it located
Allows for water level to be measured without turbulence. Located on the steam drum. Upper part in steam space, lower attached to water space
52
What is a sight glass and where is it located
Located on water column. Visual indication of water level. Is not exact due to density differences between drum and water column
53
What is a low water cut off and where is it located?
Located on water column. Uses a float to shut off pumps and high water level and cuts boiler fuel in low water situations to save boiler from damage
54
What is the procedure for checking water level in boiler
Blow down and check sight glass. Looking for lively water in glass upon closing blowdown valve
55
What would you do if you suddenly lost water level in boiler?
Check water level to verify. Line up feed pump to restore water level. Reset low water cut off. Boiler will purge and restart
56
How would you proceed to fill a boiler
Slowly full with cool, soft water. Vents open, drains closed
57
What is a dry pipe?
T shaped pipe in steam drum @ boiler outlet. Helps prevent priming by changing direction of steam to remove water
58
What is a continuous blow down valve and where is it located?
Located on steam drum, placed at water/steam interface. Drain that’s always open, uses metering valve to control flow
59
How often should you blow down a boiler?
Good practice to blow down once a shift
60
How many blow downs are found on a boiler
Five, continuous, quick bottom, slow bottom, one on water column, one on sight glass
61
What is a fusible plug and where is it located?
Plug made with a soft metal core. Placed just above lowest permissible water level. When exposed to heat due to low water situation, the metals will melt, producing a loud whistle to notify operator
62
What is the proper blow down procedure
Open quick valve first, then slow. Close in reverse order
63
What is the method for controlling blow down?
Continuous - metering valve
Bottom - globe valve
64
What type of valves are used for continuous and bottom blow down
Bitterly valve for continuous. Gate for quick bottom, globe for slow bottom
65
Is it ok to blow down a boiler directly to the sewer?
No. Continuous goes to flash tank. Bottom goes to blow down tank
66
What safety devices are built in to a boiler?
Low water cut off, safety valves, fusible plug, purge
67
What is an air cock and what is a vent valve?
Air cock is built in to a pump to purge air. Vents are built in to a boiler to relieve pressure on places like the steam drum
68
Explain why a mud drum should be blown down
Sediment builds up when phosphates are used to treat calcium. Forms as sludge on the bottom of the boiler
69
What is a steam separator and where would you find one?
Removes moisture from steam. An example is a dry pipe, found at the boiler steam outlet
70
What would you do if sight glass was full of water?
Blow down sight glass to verify high level. If true probably low water cut off issue. Shut off pump, open blow down. Trip boiler and reset.
71
What would you do if sight glass broke?
Use tricocks to verify level. Isolate sight glass until repair can be made
72
How would you test a boiler for safe operation
Hydrostatic test, run a purge. Check safety devices
73
What is a hydrostatic test and how would you perform one?
Test to verify safe operating conditions under high pressure. Apply pressure to 1.5 times normal operating pressure and hold for a set amount of time
74
How would you lay up a boiler for a short period or a long period?
Short term, wet layup. Keep filled with alkalinity at 200ppm and sulfite @ 100ppm
Mid length, dry layup. Use desiccant to absorb moisture.
Long term, fill with nitrogen
75
How often would you inspect a boiler?
Annually
76
Give three areas to inspect on a boiler
Tubes
Refractory
Low water cut off
77
How are water tubes cleaned on a boiler
Outside of tubes with a vacuum. Use knocker inside tube (mechanical) to knock loose buildup. Flush with mild acid solution (chemical)
78
How are fire tubes cleaned in a boiler?
With brush attachment on a vacuum, pushed through tubes
79
What reaction would you have to a tube failure
Make repair plan and shut down boiler. Continue to maintain water level until boiler cools. Make weld repair as necessary, or change out entire tube.
80
When is a hydrostatic test required?
Any time pressure components need to be tested, after a shut down or repair is made
81
What are the requirements for proper combustion
Fuel source, turbulence, and oxygen at theoretical ratio
82
What would you do if you lost the boiler feed pump
Reset pumps after blowing down sight glass to verify low level. If water level is critically low, trip boiler. Do not add water to exposed tubes. Monitor after restart to troubleshoot condition
83
What actions should be taken after relieving prior shift. What is the first thing to check?
Go over logbook, walk down boiler, perform water test. First thing to do is to check water level.
84
What information would you find on a boiler name plate?
Year installed, horsepower, serial number, manufacturer
85
What information would you find in a boiler room log?
Times the boiler was blown down, anomalies and events, times safety’s were tested
86
Describe how gas passes through a boiler
Through multiple passes, from plenum chamber and diverted through set of tubes at back wall. Through more tubes and diverted again at the far wall. Eventually exits and leaves stack.
87
How would you light a fire in a boiler
Have proper water level, vented, verify valving. Run a purge. Bring up boiler in manual and in low fire.
88
How would you proceed to raise steam in a boiler?
Bring up pressure gradually. When close to operating pressure put boiler in auto
89
What are safety precautions for burning oil?
Must be stored at certain temps, atomizer at certain temps, and use dry steam to propel oil
90
What are safety precautions for burning gas?
Boiler purge, fuel sensors to halt gas flow if flame is lost, monitor for gas leaks
91
What are the safety precautions for burning coal?
Need to prevent dust explosions and keep coal dry to prevent sulfuric acid from forming
92
What is flare back? How can it be prevented?
Residual gases in furnace can flash off upon start up. Purge before firing
93
What problems can occur from rapidly changing boiler loads?
On an upswing water level can swell, cutting off feed pump. Results in a low water condition. On downswing water will drop, causing pumps to start and cause high water issues.
94
What would you do if the fire went out in a boiler
Purge and restart. Troubleshoot cause
95
Name 5 items on a boiler
Safety valve, water column, sight glass, low water cut off, tricocks, blowdown, etc.
96
Describe a scotch marine boiler
Fire tube boiler, generally 4 passes. Common on ships. Has more than one furnace
97
What are man holes and hand holes for?
For boiler inspection and access. Man doors are used for boiler entry
98
What would cause smoke from a boiler stack?
Smoke is caused by incomplete combustion, most often due to a lack of oxygen due to insufficient primary air
99
How would you proceed to make repairs to superheater tubes?
Use a tube spreader because the superheater bundle tends to be compact. Make repairs as usual, plug or jump, have code welder do the welding.
100
What is a boiler water wall?
Generating section of a boiler. Part of furnace walls
101
How are water tubes connected to boiler steam drum?
Sealed by rolling. Tube is pressed to hole and beaded to help with heat transfer.
102
What is the difference between a tube and a pipe?
Tubes are generally 3 inches, pipes can be any size
103
Describe a coal pulverizer
Ball and race style, balls follow track to crush coal. Small particles fall through holes in track. A hammer mill style is a machine with a series of hammers that does the same thing
104
What is engine horsepower?
Use the PLAN formula. PLAN/33000 p- pressure x l- length of stroke x a- area of piston x n- rpm
105
What is a condenser
Series of tubes cooled by water. Steam travels over the tubes to condense and disperse
106
How does a condenser transfer heat?
With a heat transfer tube bundle. Tubes have cool water traveling inside, witch takes in the heat of the steam
107
What is a duplex pump?
Steam engine - two steam pistons and 2 water pistons. Pumps on both forward and return strokes, so no lost motion. Used as a feed water pump.
108
What is your plants operating pressure?
1200 lbs
109
Describe a copes feed water regulator
Uses thermostatic tube. Transition point between water and steam that follows drum level. Tube expands from heat when water level is low, triggering feed reg to open.
110
Where would each type of boiler be used?
Fire tube - used in low pressure applications such as schools or hospitals
Water tube - used in high pressure applications like industrial settings
111
What could result from draining a boiler too quickly?
Damage to tubes due to high temps. If not properly vented could cause damage from negative pressure
112
What determines blow down?
Conductivity and alkalinity for continuous blow down. Hardness creating sludge for bottom blow down
113
What requirements are there for entering a boiler?
Follow general safety protocols such as lock out tag out and confined space permits. Requirements are site specific
114
What are the requirements for complete combustion
Time, temp, turbulence, having correct amount of air
