Air Flashcards
What controls char bed height
Secondary FD fan
What completes the combustion process of the gases and liquor particles that escape the lower furnace
Tertiary FD fan
What does the Tertiary fan do
completes the combustion process of the gases and liquor particles that escape the lower furnace
What happens if you run the boiler over limits
Effects emissions
Carry over
Opacity
Cause wear on boiler and aux equipment
What does it mean to run the boiler over limits
You are running over a 97.6
What happens if you run below aim rate
Effect reduction efficiency
Liquor inventories
Thermal efficiency and emissions
What happens during a low air / black liquor ratio
Incomplete combustion and high TRS
What happens during a high air / black liquor ratio.
Too much excess air?
Low thermal efficiencies
Higher emissions
Cold end corrosion
What is cold end corrosion
Sulfur corrosion at the cold end of the boiler
If you increase negative furnace draft what will happen
Increase ID fan speed
What effect does a positive furnace draft have?
Positive draft will cause the boiler to blow back
If un shattered smelt reaches the green liquor in the smelt tank what could happen
It could create large explosions
What is shattering steam?
Steam applied by the shattering steam nozzles to the smelt leaving the spout
What is the purpose of shattering steam?
Break up the smelt from each smelt spout into small droplets to prevent dissolving tank explosions
What is a blackout
When the char bed shape changes and causes black liquor or char to block or partially block the primary air ports
What is black liquor made of
Its a water based solution of inorganic chemicals used to cook wood chips and
Organic chemicals produced from the wood during the cooking process in the digesters
What is carry over?
Liquor which burns in suspension and is carried up the flue gases
What is Na2S
Sodium Sulfide
Component of liquor that acts as a catalyst to speed up the cooking process in Digesting
What is Na2SO4
Sodium Sulfate
Saltcake sodium and sulfur bearing chemicals that come from the combustion of black liquor
What is Na2CO3
Sodium Carbonate
A chemical compound in liquor that comes from the combustion of black liquor
What can lead to acid rain
NOx
Nitrogen Oxides
What is NOx
Nitrogen Oxides
Various oxidized nitrous gases formed during combustion at high temperature
The source of the nitrogen can be the fuel, or airborn nitrogen
What is liquor that has been through the evaporators
50% solids
Strong black liquor
What is the process inside the scrubbers
Gases from the smelt tank are being washed down with weak green liquor. Which drain back into the smelt tank
What is viscosity
A measure of the thickness or resistance to flow of a liquid
What is a windbox
The air distribution box that the FD fans use to blow to the air ports of the boiler
What are the major componets of smelt
Sodium Sulfide (Na2S) Sodium Carbonate (Na2CO3)
Is there a high black liquor density trip
No just a high alarm
What should the % soilds be coming from the east 70% tank
68 to 70%
What does MCR stand for
Max continuous rating
What is the minimum steam flow to achieve the blue black liquor firing ok light
30 % MCR
Or about 105 mpph
At what angles do the liquor nozzles oscillate
-5 up
-20 down
15 left
15 right
How much steam is used in the direct heater
150 psi steam
Why does the direct heater use more steam
Because it is hotter steam there is more heat and less condensate for each pound of steam used.
Dilutes liquor less
What type of steam does indirect heater use
50 psi steam
Where does the condensate from the heater go
The indirect heater can send its condensate to either #1 or #2 BLE steam condensate flash tanks
How can you tell if the heater is plugged
Black liquor pump vfd output will go high
Liquor rate maybe lost
Back pressure between the recirc pump and indirect heater will increase
What does high pressure on one burner gun but not the other indicate
Plugged liquor nozzle or hose
Bad pressure transmitter
How is the liquor system set up for maintenance mode
Idk
How does the indirect heater work
Steam contacts the surface of the tube in which black liquor is flowing, condenses, transfers its heat to the tube and black liquor.
The condensate then flows out of the heater in a separate stream from the black liquor.
How does the direct heater work
Steam is directly spraged into the black liquor to control the temperature.
The condensate that is formed becomes part of the black liquor
What is the minimum black liquor flow required to burn liquor without fuel oil
30 mcr
Where is the dirty wash water sent from the liquor system
The spill tank using the standby pump
What are the wash water supply sources
Water at the 70% tank
Hose in tne boiler mix tank
What effect does bed size have on reduction efficiency
Idk
What is the typical reduction efficiency for the #2 recovery boiler
Boiler averages 95 - 96 %
What is reduction efficiency
How completely the conversion of sulfur to sodium sulfide has taken place in the boiler
What does reduction efficiency indirectly indicate
Bed temperature
Since the reaction requires heat
If the boilers dry target rate has not changed but the density goes up from 63% to 68% what happens to the
Wet firing rate
Burner pressure
Droplet size off of the nozzles
Wet rate goes down
Burner pressure goes down
Droplet size will increase
How do density meters effect rate control
High density will lower rate
Low density will increase rate
What is light oil and what is its purpose
A form of diesel used to keep foam down in the boiler mix tank
What is the location that condensate goes from the indirect heater to what
1 evap flash tank
What are the different types of air introduced into the boiler
Primary air
Secondary air
Tertiary air
What is the 5 minute boiler purge
Purge of whole boiler to remove combustable gases
How is air used to control bed shape
Primary air shapes the bed
Secondary air controls the height of the bed
How is air used to control bed height
Secondary fd fan sends air in and cuts the top off the bed
What is the main purpose of the primary air
Shape the bed and help with combustion process
What is the main purpose of the secondary air
Control the bed height by cutting the top off the bed also helps with the combustion process
What is the main purpose of the tertiary air
To polish the flue gases of CO and TRS
What is CO
Carbon monoxide
A poisonous gas resulting from the incomplete burning of natural gas and other material containing carbon such as oil and gas
How is total air adjusted
By increasing the air to liquor ratio
What problems can occur if windbox pressures operated too high
Push fireball up
Primary too high will cause bed to fall over
What problems can occur if windbox pressures are operated too low
Liquor wont burn
Big bed which will fall over and cause a blackout
What is excess oxygen ( O2 )
Extra air used
Why do you not operate with too high excess 02
Pushing air thru Precipator to fast
Fouling up boiler
Raising fire ball
Why do we not operate with too low of excess O2
Not enough for full combustion
How is excess oxygen controlled at the boiler
Air to liquor ratio and Air splits
What must be done to get a good furance draft reading
Rod out the furnance draft tap twice per shift
Where is the boiler O2 reading at on the boiler
South side of boiler on same level as mud drum
What happens if one or all of the sooth blowers are out of service for a extended length of time
Plug up your boiler
How long can you not run sooth blowers before having to reduce rate
30 minutes
What are the time limits for soothblower issues
30 minutes reduce rate
2 hours pull liquor
If you have a blackout what checks should be made to ensure that the air system is not helping cause the blackout
….
What are system variables can have an effect on TRS levels
What steps should be taken to eliminate high TRS when it occurs
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What effects do APC’s have on the boiler
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What is stack opacity
…
Why is it critical that we keep the stack opacity in limits
State regulates it
What equipment most affects stack opacity
The precipator
What are our environmental permit operating guidelines relating to the smelt dissolving tank scrubber
…
What is the backup system to the scrubber and when should it be put in service
Demister
Any time the scrubber fan can not run or there is an issue with the scrubber vessel
What is the maximum black liquor firing rate allowed by our environmental permit
…
What system do we have for preventing over firing and how does it work
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What does ground half a set mean.
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How do you ground half a set
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What variables affect precipitator collecting efficiency
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If opacity is high what things do you check to improve opacity
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What are sootblowers and what is there purpose
..
How do sootblowers affect the draft in the furnace
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Why is it critical that TRS stay in limits
Because the state regulates it
Describe the states TRS permit limit for #2 recovery boiler
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What is the purpose of the precipitator
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What is CO
…
How is CO controlled
…
What air system variables effect CO levels
…
What is the precipitator collecting and where does it come from
Salt cake from the furance
Describe the purpose of the ID fan
To remove gases from the boiler and to keep a negative draft on the boiler
Describe how the ID fan is controlled on the TDC
…
In what manner is the ID fan set up to control
Cascade off of the furance pressure
How is air temperature controlled
Primary and secondary air use air heaters which use 50 and 150# steam which the tertiary air use ambant air temp from outside
Opacity on normal op
20%
Opacity during start up,shutdown, malfunction
35% for 4 hours
Opacity during general malfunction
35% for 2 hours
What helps shape the char bed
Primary FD fan
