a16 jaimes keise

8/12/2019 A16 Jaimes Keise

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PERFORMANCE OF ALTERNATESUPERHEATER TUBE MATERIALS IN

EXTREME BOILER ENVIRONMENTSJAMES KEISER, Oak Ridge National Laboratory,

W. B. A. (SANDY) SHARP, SharpConsultant, andDOUGLAS SINGBEIL, FPInovations


2/31


3/31

This DOE-Funded Project Had Five Tasks Collect information on different boiler designs and

experience with alternate superheater tube materials Determine if there are economic benefits to using

alternate superheater designs or more corrosionresistant tube alloys

Conduct laboratory corrosion studies in simulated

biomass boiler environments Expose corrosion probes in selected, especially

aggressive, biomass-fired boiler environments

Report results of these studies


4/31


5/31

Availability Of Energy InSteam Is Function Of Temperature

Specific available energy in steam (kJ/kg)increases 11.4% from 500 to 600 C at 100 bars (1,450 psi)increases 11.0% from 500 to 600 C at 50 bars (725 psi)

To gain the most power from your fuel, have your boiler produce thehottest steam its metallurgy allows

However , the same heat input generates 6.6% - 7.2% less steam volumewhen the steam temperature is raised 100 Celsius degrees


6/31

Corrosivity Of BiomassFuels Forces Inefficient Power Generation

Kamuk (Ramboll) review of boiler efficiencies, 2010

To determine if higher temperature operation would providesufficient benefits to justify changes, energy calculations were

made for 2 recovery boilers and 3 other biomass boilers


7/31

Calculations Show Large Value For IncreasedPower In The Five Typical Biomass Boilers

Conditions Recovery Boilers Biomass Boilers

B M C H M

+50

C steam @$40/MWh +$1.54m +$2.52m/y +$2.94m/y +$1.33m/y +$1.26m/y

@$80/MWh +$3.08m +$5.05m/y +$5.89m/y +$2.66m/y +$2.52m/y

+100 C steam

@$40/MWh +$2.45m/y +$4.45m/y +$5.61m/y +$2.60m/y +$2.42m/y@$80/MWh +$4.91m/y +$8.90m/y +$11.21m/y +$5.19m/y +$4.84m/y

Potential costs of making up steam losses (likely not large)

are not included in calculations for biomass-fuelled boilers


8/31

Comparison Shows Value Of Increased Power In

Terms Of The Cost Of Tube Upgrades, ChemicalAdditives And Boiler/TG Re-designsAt constant fuel costs and constant firing conditions, the valueof the hotter steam is worth millions of dollars per boiler per

year, equivalent to:$1,200 to $10,676/m for 1050m of more corrosion-resistantsuperheater alloys with 5-year life (35p x 10t x 3m)$1,260,000 to $11,210,000 per year to remove corrosives fromfuel or to apply additives$6,300,000 to $56,050,000 over 5 years to redesignboiler/upgrade TG

Efforts to identify/develop RB SH alloys that could handlehigher temp. flue gas conditions in biomass-fuelled boilerwould have substantial national benefits


9/31

Equipment Redesigns Would Provide One Method

To Enable Higher Temperature OperationCorrosion-resistant alloy SH tubesTurbine capable of handling higher temperature steam

Install attemporatorsEmpty pass between furnace and SHChlorine Trap upstream of SH Design SH for very rapid replacement

Operate SH above ash dew point temperatureCFB with SH moved out of flue gases into recirculatedfluidizing mediumExternal SH fired by less-corrosive fuel


10/31

Another Option Is To Use Fuel TreatmentsThat Enable Higher Temperature

Dilute corrosive biofuelsLeach corrosives out of biofuels

Use additives that convert alkali chlorides to sulfates,e.g. (NH4)2SO4 SO3 + 2NH3 + H2O

2KCl + SO2 + O2 + H2O K2SO4 +2HCl

Use additives that convert alkali salts to silicates, e.g.kaolin (40-60 wt% Al2O 3.SiO2)

The other option is to utilize corrosion resistant alloys

for the highest temperature superheater tubes


11/31

Four Sites Were SelectedFor Exposure Of Corrosion Probes

Covington, VA, recovery boiler 80-85% hardwood highpotassium content low melting temperature ash Crofton, BC, power boiler bark from seawater-floated logs

high chlorine and sodium Gadsden, AL, power boiler co-firing coal and limited amount

of biomass (wood) combination of sulfur, chlorine and alkalimetals

Port Mellon, BC, power boiler uses bark from beetle-killedpine trees, seawater-floated logs and construction waste combination of sodium, chlorine, and, possibly, heavy metals(zinc, lead, etc.)

This summary presents results from examinationof corrosion probes exposed in these four boilers


12/31

Components Used For Corrosion Probe

Ethernet ortelephone connectionto computer at ORNL

Computer and monitorin atmosphere

controlled room

Instrument box mountednear corrosion probe

24 thermocouplewires and valvecontrol cable

Corrosion probe insertedthrough manway door


13/31

Samples For Corrosion Probe Designed To Be

Interlocking And To Accommodate ThermocoupleCross sectionof sample

Isometric viewof sample

Photo of samples showing thermocouplesextending through two samples

Photo of sample with thermocoupleshield welded in place


14/31

Nine Alloys Were Selected For

Exposure In The Corrosion ProbesAlloy UNS

numberFe Ni Cr Mo Co Mn Al Si C Other

310H SS S31009 Bal 19.10 24.30 0.25 0.55 0.045

Haynes 214 N07214 3.56 Bal 16.08 0.03 4.22 0.12 0.04 Y=.004, Zr=.011Sanicro 28* N08028 35 31 27 3.5 1.8 0.2 0.01

602CA N06025 9.60 62.20 25.30 2.30 0.03 0.170 Y=0.07, Zr=0.09

HR160 N12160 0.63 Bal 28.00 0.27 30.20 2.75 0.056

Inconel 690* N06690 9 62 29 0.02

HR120 N08120 36.26 36.68 24.74 0.07 0.11 0.16 0.73 0.057 N=0.21

Esshete 1250* S21500 Bal 9.5 15 1 6.3 0.5 0.1 Nb=1, V=0.25,B=0.006

347H SS S34709 Bal 9.02 17.21 0.57 0.048

*Nominal values


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16/31

Average Daily TemperaturesDuring 2,000 hr Exposure In Covington Recovery Boiler

Several thermocouples stopped functioning during the exposure These data were used to estimate the sample temperatures during

the exposure


17/31

Using Thermocouple Data, Average Temperatures

Were Calculated For Each Sample On Covington Probe

300

350

400

450

500

550

600

650

700

1 4 7 10 13 16 19 22 25 28

T e m p e r a t u r e

( C

)

Sample Number

TopTemperature

BottomTemperature


18/31

Micrographs Show Variation In Subsurface Attack OfN06025 As Function Of Exposure Temperature

565 C


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20/31

There Are Many Similarities In Results Of The Laboratory

Corrosion Studies And The Field ExposuresCorrosion Probe T = 570C Corrosion Probe T = 600C Laboratory Tests T = 625C

Alloy AffectedMetal (mm)



N12160 0.19 N12160 0.28 N06025 0.09

N06690 0.27 S21500 0.41 S21500 0.18

S21500 0.33 N06690 0.50 N06690 0.25

N08120 0.50 N08120 0.62 N08120 0.27

N06025 0.51 N06025 0.70 S31009 0.30

S31009 0.70 S31009 0.80 N12160 0.31

N08028 0.90 N08028 1.20 N08028 0.35

N07214 1.50 N07214 2.00 N07214 2.50

Corrosion probe exposure was for 2,000 hoursLaboratory tests were conducted for 1,000 hours


21/31

Found Less Variation In AverageDaily Temperatures Of Samples On Probe In Gadsden

Co-Fired Power Boiler

0 20 40 60 80 100 120 1400

100

200

300

400

500

600

700

T h e r m o c o u p

l e T e m p e r a

t u r e s

C

Operating Days

TC 1 TC 2 TC 3 TC 4 TC 5 TC 6 TC 7 TC 8 TC 9 TC 10 TC 11 TC 12 TC 13 TC 14 TC 15 TC 16 TC 17

TC 18 TC 19 TC 20 TC 21 TC 22 TC 23 TC 24

Corrosion Probe Gadsden Alabama Average Daily Temperatures


22/31

Found Limited Thickness LossOf Samples Exposed In Gadsden Co-Fired Boiler

450

500

550

600

650

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45

E x p o s u r e T e m p e r a t u r e

( C

)

Material Affected (mm)

310H

602CAHR120

Haynes 214

HR160

Esshete 1250

347H

Sanicro 28Inconel 690Max Operating

Temperature

Goal


23/31

Found Significant Variation OfTemperatures Of Samples In Crofton Power Boiler

Days of exposure


24/31

Calculated Temperatures Of Samples On

Corrosion Probe In Crofton Power Boiler


25/31

Wall Thickness Loss Of SamplesExposed In Catalyst Paper (Crofton) Power Boiler

375

400

425

450

475

500

525

550

575

0 0,3 0,6 0,9 1,2 1,5

E x p o

s u r e T e m p e r a t u r e

( C

)


310H SS

602CA

HR120

Haynes 214

HR160

Esshete 1250

Sanicro 28

Inconel 690

347H SS

Max Operating Temp

Goal


26/31

Plots Showing Performance Of Individual Alloys

Helps Differentiate Between AlloysNote: The Goal For This Boiler Is 500C

375400425450475500525550575

0 0,5 1 1,5

602CA

375400425450475500525550575

0 0,1 0,2 0,3 0,4 0,5

HR120

375400425450475500525550575

0 0,5 1 1,5

Haynes 214

375400425450475500525550575

0 0,1 0,2 0,3 0,4

Esshete 1250

375400425450475500525550575

0 0,5 1 1,5

Sanicro 28

375400425450475500525550575

0 0,1 0,2 0,3

347H SS


( C

)

Affected material (mm)


27/31

Wall Thickness Loss Of SamplesExposed In Howe Sound Pulp & Paper Power Boiler

350

375

400

425

450

475

500

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8

E x p o s u r e T e m p e r a t u r e

( C

)


310H

Haynes 214

Sanicro 28

602CA

HR120

Esshete 1250

Goal

Essentially all samples showed a peak (unexplained) in corrosion in the 420-430 C range

Max Operating Temp


28/31

Several Issues AffectedThe Howe Sound Corrosion Probe The available access point was a port that positioned

the probe only a few inches above the bull nose Temperature indications showed very little difference

between the top and bottom of the probe The probe temperatures did not reach as high a level

as desired Samples in the 420-430C temperature range

experienced inconsistently high rates of material loss


29/31

If 420-430C Data Points AreNot Considered, Several Alloys Perform Well

But At Lower Than Desired Temperatures

350

375

400

425

450

475

0 0,1 0,2 0,3 0,4

310H

350

375

400

425

450

475

0 0,2 0,4 0,6

Haynes 214

350

375

400

425

450

475

0 0,1 0,2 0,3 0,4

602 CA

350

375

400

425

450

475

0 0,1 0,2 0,3 0,4

Sanicro 28

350

375

400

425

450

475

0 0,2 0,4 0,6

HR120

350

375

400

425

450

475

0 0,2 0,4 0,6 0,8

Esshete 1250

Results from this probe are not sufficient to draw conclusions


( C

)

Affected material (mm)


30/31

Summary Thermodynamic calculations show significant financial

benefit for operating biomass-fired boilers withsuperheater temperatures 50 or 100 Celsius degrees higher

Corrosion probe results from the potassium-rich recovery

boiler showed 3 alloys demonstrated favorable propertiesat 570C Corrosion probe results from the co- fired boiler dont show

a clear difference in alloy performance Corrosion probe results from the chloride-rich power boiler

showed many alloys are acceptable at 500C but fewer aresuitable at 525C


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Thanks for your attention!

Ill try to answer anyquestions you have.

a16 jaimes keise

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