© 2003 Paprican 1

Red Hot VideoRed Hot Videoof Combusting Liquor & Smeltof Combusting Liquor & Smelt

at Primary Airportsat Primary Airports

Black Liquor Colloquium - Utah

Laurie FrederickDoug SingbeilJoey Kish

13 May 2003

Black Liquor Colloquium - Utah

Laurie FrederickDoug SingbeilJoey Kish

13 May 2003

© 2003 Paprican 2

• Observations– Lifespan of a Combusting

Particle

– Coating of Tubes

– Two Steady States

• Activity not causing >500°C excursions

OverviewOverview

Red (& White) Hot Video

• Background to Boiler Video Camera Probe

© 2003 Paprican 3

• Cracking of composite tubes at primary airports

• Associated with temperature excursions & cycling

• Cause of high temperatures - Unknown

• Since Feb.2001: Five successful camera probe variations

• ~ 35+ hours Video from

5 trips to 3 mills

• One design selected:

“Boiler View”

Why Build a Camera Probe?Why Build a Camera Probe?

TC1 TC2

© 2003 Paprican 4

Stage & Temperatures

(°C) Droplets PAPRICAN’S

OBSERVATIONS Eg.

Drying <= 300

Droplets swell ~1.5x ?

Devolatilization 300 > 800

Puffs up, bright yellow flame

produced Gray and Swelling

Char Burning 800 > 1200

Particle shrinks, mainly

C & Na salts

Hollow – White: Large or Medium reducing to

Solid – White: Small or Tiny

Smelt Molten Salts - C depleted

Clear Liquid or

Clear with fine black particles

Black Liquor Life SpanBlack Liquor Life SpanHupa & Frederick 1987Hupa & Frederick 1987

© 2003 Paprican 5

BoilerBoiler--View Clip: Swelling ParticlesView Clip: Swelling Particles

© 2003 Paprican 6

BoilerBoiler--View clip: Medium to Large ParticlesView clip: Medium to Large Particles

© 2003 Paprican 7

BoilerBoiler--View clip: Small to Tiny ParticlesView clip: Small to Tiny Particles

© 2003 Paprican 8

Is there something on the tubes?Is there something on the tubes?• Yes - all fireside tube surfaces are coated• ~ 2 mm thick below 1° and fairly uniform• Coating either ductile or brittle

TC2TC1

@ Shutdown Burning Oil

© 2003 Paprican 9

Recognition of Two Steady StatesRecognition of Two Steady States• Expanded time

scale revealed two dominant temperatures

• Video revealed two associated physical states: – Coated– Protected

300

350

400

450

500

11:00 12:00 13:00 14:00 15:00 16:00

Tem

pera

ture

( °C

)

TC1

300

350

400

450

500

13:10 14:10Time

Tem

pera

ture

( °C

) TC1

300

350

400

450

500

0:00 8:00 16:00 0:00

Tem

pera

ture

( °C

) TC1TC2

24 hr

5 hr

1 hr

© 2003 Paprican 10

Coated Steady State Coated Steady State ( CSS )( CSS )

Very Few Particles & Bed Low:• Tubes coated in a uniform “white” layer

• Temperatures on tube bends steady ( + 1 - 3°C )

• Range 390° - 410°C; Average may drift over hours

• May have clear liquid flow over surface

• Example Video:

Baseline

300

350

400

450

500

15:15 15:30 15:45

LH25-1

LH25-2

© 2003 Paprican 11

BoilerBoiler--View clip: Coated Steady StateView clip: Coated Steady State

© 2003 Paprican 12

Protected Steady State Protected Steady State ( PSS )( PSS )

Char Bed Particulate Covering Tube Bends:• Temperature steady @~320°C• High stable bed of compact particulate over coated

thermocouples• Particulate excluding radiation & atmosphere• Example Video:

High Bed

300

350

400

450

500

10:35 10:50 11:05

RH25-1

RH25-2

© 2003 Paprican 13

BoilerBoiler--View clip: Protected Steady StateView clip: Protected Steady State

© 2003 Paprican 14

What Seems to Protect ThermocouplesWhat Seems to Protect Thermocouplesfrom Radiation and Atmosphere ?from Radiation and Atmosphere ?

• Some protection provided by coating on tubes• Most Effective Protection:

– A high compact bed of particles, usually grey, over coating

=> “Char Bed” Protected Steady State (PSS)

• Two Other Conditions Approach PSS:– Sticky grey particles forming a layer over coating on tubes,

above bed level– A buildup of fine black particles, produced as particles melt,

washed down the tubes and deposited by liquid at bed interface

© 2003 Paprican 15

Char Particles

Cross Section at Thermocouple (TC)Cross Section at Thermocouple (TC)

TC

TC Shield

Tube Wall Coating

Char Bed

© 2003 Paprican 17

What Items What Items Are Not the Sole CauseAre Not the Sole Causeof > 500°C on tube bends?of > 500°C on tube bends?

• Medium to tiny white particles landing

• Surface washed with liquid or left dry

• Bed surface rising & lowering

• Darkening surface deposits

• Primary or Secondary port rodding

© 2003 Paprican 18

SummarySummary• Tubes are normally coated on the fireside with a thin,

adherent, white coating• Protection of the coated tubes from radiation and

atmosphere, may occur 3 ways:– High compact char bed against the wall (most effective)– Sticky particle layer on the tube surface, above the char bed– “Black fines” deposited to form a smooth dense dark layer

• When the Bed was low, and the thermocouples not impacted by particulate, no temperatures above 500°C were noted