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Recover Boiler > Air > Flashcards

Air Flashcards

1
Q

What controls char bed height

A

Secondary FD fan

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2
Q

What completes the combustion process of the gases and liquor particles that escape the lower furnace

A

Tertiary FD fan

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3
Q

What does the Tertiary fan do

A

completes the combustion process of the gases and liquor particles that escape the lower furnace

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4
Q

What happens if you run the boiler over limits

A

Effects emissions
Carry over
Opacity
Cause wear on boiler and aux equipment

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5
Q

What does it mean to run the boiler over limits

A

You are running over a 97.6

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6
Q

What happens if you run below aim rate

A

Effect reduction efficiency
Liquor inventories
Thermal efficiency and emissions

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7
Q

What happens during a low air / black liquor ratio

A

Incomplete combustion and high TRS

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8
Q

What happens during a high air / black liquor ratio.

Too much excess air?

A

Low thermal efficiencies
Higher emissions
Cold end corrosion

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9
Q

What is cold end corrosion

A

Sulfur corrosion at the cold end of the boiler

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10
Q

If you increase negative furnace draft what will happen

A

Increase ID fan speed

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11
Q

What effect does a positive furnace draft have?

A

Positive draft will cause the boiler to blow back

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12
Q

If un shattered smelt reaches the green liquor in the smelt tank what could happen

A

It could create large explosions

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13
Q

What is shattering steam?

A

Steam applied by the shattering steam nozzles to the smelt leaving the spout

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14
Q

What is the purpose of shattering steam?

A

Break up the smelt from each smelt spout into small droplets to prevent dissolving tank explosions

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15
Q

What is a blackout

A

When the char bed shape changes and causes black liquor or char to block or partially block the primary air ports

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16
Q

What is black liquor made of

A

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

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17
Q

What is carry over?

A

Liquor which burns in suspension and is carried up the flue gases

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18
Q

What is Na2S

A

Sodium Sulfide

Component of liquor that acts as a catalyst to speed up the cooking process in Digesting

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19
Q

What is Na2SO4

A

Sodium Sulfate

Saltcake sodium and sulfur bearing chemicals that come from the combustion of black liquor

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20
Q

What is Na2CO3

A

Sodium Carbonate

A chemical compound in liquor that comes from the combustion of black liquor

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21
Q

What can lead to acid rain

A

NOx

Nitrogen Oxides

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22
Q

What is NOx

A

Nitrogen Oxides
Various oxidized nitrous gases formed during combustion at high temperature
The source of the nitrogen can be the fuel, or airborn nitrogen

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23
Q

What is liquor that has been through the evaporators

50% solids

A

Strong black liquor

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24
Q

What is the process inside the scrubbers

A

Gases from the smelt tank are being washed down with weak green liquor. Which drain back into the smelt tank

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25
Q

What is viscosity

A

A measure of the thickness or resistance to flow of a liquid

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26
Q

What is a windbox

A

The air distribution box that the FD fans use to blow to the air ports of the boiler

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27
Q

What are the major componets of smelt

A 
Sodium Sulfide (Na2S)
Sodium Carbonate (Na2CO3)
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28
Q

Is there a high black liquor density trip

A

No just a high alarm

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29
Q

What should the % soilds be coming from the east 70% tank

A

68 to 70%

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30
Q

What does MCR stand for

A

Max continuous rating

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31
Q

What is the minimum steam flow to achieve the blue black liquor firing ok light

A

30 % MCR

Or about 105 mpph

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32
Q

At what angles do the liquor nozzles oscillate

A

-5 up
-20 down
15 left
15 right

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33
Q

How much steam is used in the direct heater

A

150 psi steam

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34
Q

Why does the direct heater use more steam

A

Because it is hotter steam there is more heat and less condensate for each pound of steam used.
Dilutes liquor less

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35
Q

What type of steam does indirect heater use

A

50 psi steam

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36
Q

Where does the condensate from the heater go

A

The indirect heater can send its condensate to either #1 or #2 BLE steam condensate flash tanks

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37
Q

How can you tell if the heater is plugged

A

Black liquor pump vfd output will go high
Liquor rate maybe lost
Back pressure between the recirc pump and indirect heater will increase

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38
Q

What does high pressure on one burner gun but not the other indicate

A

Plugged liquor nozzle or hose

Bad pressure transmitter

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39
Q

How is the liquor system set up for maintenance mode

A

Idk

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40
Q

How does the indirect heater work

A

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.

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41
Q

How does the direct heater work

A

Steam is directly spraged into the black liquor to control the temperature.
The condensate that is formed becomes part of the black liquor

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42
Q

What is the minimum black liquor flow required to burn liquor without fuel oil

A

30 mcr

43
Q

Where is the dirty wash water sent from the liquor system

A

The spill tank using the standby pump

44
Q

What are the wash water supply sources

A

Water at the 70% tank

Hose in tne boiler mix tank

45
Q

What effect does bed size have on reduction efficiency

A

Idk

46
Q

What is the typical reduction efficiency for the #2 recovery boiler

A

Boiler averages 95 - 96 %

47
Q

What is reduction efficiency

A

How completely the conversion of sulfur to sodium sulfide has taken place in the boiler

48
Q

What does reduction efficiency indirectly indicate

A

Bed temperature

Since the reaction requires heat

49
Q

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

A

Wet rate goes down
Burner pressure goes down
Droplet size will increase

50
Q

How do density meters effect rate control

A

High density will lower rate

Low density will increase rate

51
Q

What is light oil and what is its purpose

A

A form of diesel used to keep foam down in the boiler mix tank

52
Q

What is the location that condensate goes from the indirect heater to what

A

1 evap flash tank

53
Q

What are the different types of air introduced into the boiler

A

Primary air
Secondary air
Tertiary air

54
Q

What is the 5 minute boiler purge

A

Purge of whole boiler to remove combustable gases

55
Q

How is air used to control bed shape

A

Primary air shapes the bed

Secondary air controls the height of the bed

56
Q

How is air used to control bed height

A

Secondary fd fan sends air in and cuts the top off the bed

57
Q

What is the main purpose of the primary air

A

Shape the bed and help with combustion process

58
Q

What is the main purpose of the secondary air

A

Control the bed height by cutting the top off the bed also helps with the combustion process

59
Q

What is the main purpose of the tertiary air

A

To polish the flue gases of CO and TRS

60
Q

What is CO

A

Carbon monoxide
A poisonous gas resulting from the incomplete burning of natural gas and other material containing carbon such as oil and gas

61
Q

How is total air adjusted

A

By increasing the air to liquor ratio

62
Q

What problems can occur if windbox pressures operated too high

A

Push fireball up

Primary too high will cause bed to fall over

63
Q

What problems can occur if windbox pressures are operated too low

A

Liquor wont burn

Big bed which will fall over and cause a blackout

64
Q

What is excess oxygen ( O2 )

A

Extra air used

65
Q

Why do you not operate with too high excess 02

A

Pushing air thru Precipator to fast
Fouling up boiler
Raising fire ball

66
Q

Why do we not operate with too low of excess O2

A

Not enough for full combustion

67
Q

How is excess oxygen controlled at the boiler

A

Air to liquor ratio and Air splits

68
Q

What must be done to get a good furance draft reading

A

Rod out the furnance draft tap twice per shift

69
Q

Where is the boiler O2 reading at on the boiler

A

South side of boiler on same level as mud drum

70
Q

What happens if one or all of the sooth blowers are out of service for a extended length of time

A

Plug up your boiler

71
Q

How long can you not run sooth blowers before having to reduce rate

A

30 minutes

72
Q

What are the time limits for soothblower issues

A

30 minutes reduce rate

2 hours pull liquor

73
Q

If you have a blackout what checks should be made to ensure that the air system is not helping cause the blackout

A

….

74
Q

What are system variables can have an effect on TRS levels

A
75
Q

What steps should be taken to eliminate high TRS when it occurs

A

…

76
Q

What effects do APC’s have on the boiler

A

…

77
Q

What is stack opacity

A

…

78
Q

Why is it critical that we keep the stack opacity in limits

A

State regulates it

79
Q

What equipment most affects stack opacity

A

The precipator

80
Q

What are our environmental permit operating guidelines relating to the smelt dissolving tank scrubber

A

…

81
Q

What is the backup system to the scrubber and when should it be put in service

A

Demister

Any time the scrubber fan can not run or there is an issue with the scrubber vessel

82
Q

What is the maximum black liquor firing rate allowed by our environmental permit

A

…

83
Q

What system do we have for preventing over firing and how does it work

A

…

84
Q

What does ground half a set mean.

A

…

85
Q

How do you ground half a set

A

…

86
Q

What variables affect precipitator collecting efficiency

A

…

87
Q

If opacity is high what things do you check to improve opacity

A

…

88
Q

What are sootblowers and what is there purpose

A

..

89
Q

How do sootblowers affect the draft in the furnace

A

…

90
Q

Why is it critical that TRS stay in limits

A

Because the state regulates it

91
Q

Describe the states TRS permit limit for #2 recovery boiler

A

…

92
Q

What is the purpose of the precipitator

A

…

93
Q

What is CO

A

…

94
Q

How is CO controlled

A

…

95
Q

What air system variables effect CO levels

A

…

96
Q

What is the precipitator collecting and where does it come from

A

Salt cake from the furance

97
Q

Describe the purpose of the ID fan

A

To remove gases from the boiler and to keep a negative draft on the boiler

98
Q

Describe how the ID fan is controlled on the TDC

A

…

99
Q

In what manner is the ID fan set up to control

A

Cascade off of the furance pressure

100
Q

How is air temperature controlled

A

Primary and secondary air use air heaters which use 50 and 150# steam which the tertiary air use ambant air temp from outside

101
Q

Opacity on normal op

A

20%

102
Q

Opacity during start up,shutdown, malfunction

A

35% for 4 hours

103
Q

Opacity during general malfunction

A

35% for 2 hours

104
Q

What helps shape the char bed

A

Primary FD fan

Recover Boiler (2 decks)

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