Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
46 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
What’s a blowoff? |
A process that removes dissolved solids from boiler water |
|
|
|
What are the 2 types of blow downs |
Continuous blowdown Mud drum |
|
|
|
Which type of blowdown removes dissolved solids? Where and at what rate? |
Continuous blowdown, from the steam drum at a constant rate |
|
|
|
What does mud drum blowdown do? |
Removes suspended solids at an intermittent rate from the mud drum |
|
|
|
What materials can blowoff pipes be made of? |
Bronze, steel, iron |
Big cold stone |
|
|
What is a slow opening valve? |
A valve that takes 5 full turns to open |
|
|
|
True or false, blowoff pipes don’t need slow opening valves |
False they need at least 1 |
|
|
|
What are different types of slow opening valve? |
Hard sealed: globe valve Y type: steam is angled reducing pressure drop |
|
|
|
What must your blowoff piping be able to deal with? |
Rapid temperature changes during blowdown, allows expansion or contraction |
|
|
|
True or false, piping doesn’t have to anchored |
False, it HAS to be in anchored to prevent stress going to boiler |
|
|
|
What is the purpose of blowoff vessel? |
Depressurizes blowoff water by vetoing steam Cools water down |
Has 2 jobs |
|
|
What is required for a blowoff vessel? |
More than 103kpa 65 degrees or less Enough thickness to handle corrosion A spot for inspections |
|
|
|
Is a blowoff vessel needed if your discharging water into a pond? |
No it’s not needed |
|
|
|
When is a bottom blow off used? |
When you have stuff sticking to hot surfaces of the lines |
|
|
|
What is a primary source of impurities? And what minds are found in it? |
Make up water, Suspended solids, dissolved gasses and hardness |
|
|
|
In regards to bottom blowoff, do large steam units need more or less blowoffs and why? |
Less, cause it’s using higher quality water |
|
|
|
Why would you never do blowoff on a water wall header? |
Interrupts flow of water to boiler and heat up tubes |
|
|
|
Why do bottom blowoff have blowoff valves connects to base of drum shell? |
All the dirt is collected at the bottom so it’ll drain all that down |
|
|
|
What are good practices when performing bottom blowoff |
Never leave it unattended Open blowoff valves slowly Only perform on 1 boiler at a time Must be done when load is low or moderate |
|
|
|
Describe a combo quick/ slow opening |
Open quick valve first and then slow down second to reduce water hammer To close do the reverse |
|
|
|
Describe the 2 seatless flow opening valve |
Valve furthest is open first and closed last Has no guard valve |
|
|
|
In a 2 seatless slow opening valves what would happen if you closed the first valve instead of the second one? |
Water gets trapped building pressure until it damages it |
|
|
|
Why do we call the bottom steam drums a mud drum? |
All the suspended solids fall at the bottom of it forming mud in the shell |
|
|
|
What does blowoff depend on? |
Rate of steam production Type/concentration of impurities Percentage of make up water added |
|
|
|
How often should blowoff should be done? |
At least once a shift, for 3-15s |
|
|
|
How often should bottom blowoff be done? |
Only once a day at most |
|
|
|
What must your boiler condition be in order to do blowoff? |
In use and under pressure |
|
|
|
Why must blowoff line be able handle shock? |
As water pressure drops, flashes into steam causes sudden rise in temperature |
|
|
|
What is the result of a sudden rise in temperature? |
Vibrations, reaction forces, rapid thermal expansion and thermal shock |
|
|
|
What provision does your blowoff pipe must have? |
Min design pressure(1550kpa) Min pipe size(50mm) 2 restriction on assembly |
|
|
|
When is surface blowdown system used? |
When condensate return contaminated with materials that stick to boiler surface |
|
|
|
What does foaming and priming cause? |
Foaming: carryover Priming: destructive water hammer |
|
|
|
What does a surface blowoff system consist of? |
Pipes are connected at boiler drums and shell Skims the boiler water surface |
|
|
|
What’s a continuous surface blowdown? How does it differ from intermittent |
Continuous uses a metering valve and is adjusted based on testing results Intermittent can only be used when boiler is under pressure |
|
|
|
What’s the purpose of CBD(Continuous Blow Down) |
To get rid of dissolved solids |
|
|
|
In a water tube boiler, how are dissolved solids created? |
Impurities on make up water |
|
|
|
What must the TDS of CBD be? |
2500, too high so risky and low is a waste |
|
|
|
Can a blowdown system be used for same stuff as blowoff? |
No because it’s not designed to deal with rapid burts of hot water |
|
|
|
How much pressure must blowdown systems handle? |
The exact same of the boilers their being used on |
|
|
|
Does a blowdown or blowoff require system, require one shutoff valve |
Blowdown |
|
|
|
What is an internal CBD collection? |
A collection pipe connected to steam drum that takes boiler water Must be 15cm |
|
|
|
How much loss of heat happens when it comes to doing CBD |
1-2% |
|
|
|
How to recover heat loss due to CBD |
Use a heat exchanger to increase makeup water temperature |
|
|
|
What are some hazards to look out for blowoff vessel if failure occurs? |
Corrosion at waterlines Erosion of internal wear plates Scale deposits Gauge operation |
|
|
|
What are some hazards to look out for blowoff valves |
Cracks Wire drawing Corrosion Erosions |
|
|
|
What are some hazards to look out for blowoff piping |
Leaky joints Gaskets Piping support No room for expansion |
|
