Biomass co-firing

solutions

Metso’s solution: Large scale

biomass gasification plant

integrated to a PC boiler

Tyler Biddle – Product Engineer

Juhani Isaksson – Gasification Dir.

From biomass combustion to new

conversion technologies

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C + H2O CO + H2 ΔH = 131.3 kJ/mol (1)

C + ½O2 CO ΔH = -110.5 kJ/mol (2)

C + O2 CO2 ΔH = -393.5 kJ/mol (3)

C + CO2 2CO ΔH = 172.5 kJ/mol (4)

CO + H2O CO2 + H2 ΔH = -41.2 kJ/mol (5)

CO + 3H2 CH4 + H2O ΔH = -206.2 kJ/mol (6)

Gasification:

History

Applications

Commercialization

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Metso CFB gasifier

Industrial experience

• Götaverken

– Atmospheric CFB gasification

– Värö project start-up 1987

• Tampella Power

– 15 MWth pressurized FB gasifier and

gas cleaning

– Piloting ended 1996

• Metso BFB & CFB boilers

– Fluid bed technology

– Project execution resources

• New gasification development

– Product gas filtration tests

– Dryer technology

– Own process dimensioning tools

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Gasification:

History

Applications

Commercialization

Metso’s Applications for

Gasification

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Gasification technologies

Position of Metso CFB gasification

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PRESSURE OXIDIZIER PROCESS FUEL SIZE APPLICATION

Atmospheric Air Fixed bed Coal SMALL 0 – 10

MW Combustion engines

Pressurized

Oxygen BFB Biofuel

MEDIUM 5-50 MW

Combustible gas for industrial furnaces

Steam CFB Oil LARGE

50 -200 MW

Fossil fuel replacement by

bio/waste in power plants

Entrained flow

Gas HUGE

200 -2000 MW

IGCC

Transport reactor

Waste Transport fuels

Flame gasification

Synthetic NG

Fuels in:

• Woody

• Agricultural

• MSW

Product Gas out:

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Heating value: 3 – 7 MJ/kg LHV (1300 – 3000 Btu/lb) Temperature: 750 – 800 °C (1380 – 1470 °F) Pressure: 5 – 30 kPag (.722 – 4.35 psig)

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Gasification:

History

Applications

Commercialization

Benefits of adding a biomass gasifier into

an existing coal-fired plant

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Produces electricity from biofuels with high efficiency

Extends the lifecycle of the existing power plant

Replaces fossil fuel with biomass in larger scale

Increases fuel flexibility

Original coal capacity can be kept

Reduces CO2 emission economically

Relatively low investment cost

Short delivery time and minimized production interference

Cost effective method to meet RPS

Co-firing with CFB gasifiers

Vaskiluodon Voima – Scope

• Metso’s scope

– Fuel receiving and handling

– Drying

– Gasification

– Boiler modifications

– Automation, electronics and instrumentation

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Wet biomass

Existing PC boiler

Instrumentation, electronics, and automation

Biomass receiving and pre-handling

Large-scale belt dryer CFB gasifier 140 MWfuel

Product gas

Dried biomass

Co-firing with CFB gasifiers

Vaskiluodon Voima

Gasifier

Drying

Storage Silos

Sampling

Screening

Receiving

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Start-up 2012

Process Gasification (45 MWe) for power generation

Fuels Forest residues (chips), Peat

Fuel Drying Waste heat from 60 – 120 °C (140 – 250 °F)

No downtime except when boiler connections are made. Total investment of less than $55 million.

Fuel handling

• Capacity • 30 truck loads/d, 3500 ft3/load

• Unloading capacity 20000 ft3/h

• Fuel handling • Screening and crushing

• Automatic sampling

• Storage silos 2 x 90000 ft3

• Beltdryer for wood biomass • Fuel moisture before dryer 47%

• Fuel moisture after dryer 34 %

• Water removal capacity 10 t/h

• Heat source for drying is the district heating circuit

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Fuel and steam

Coal 100 %

Coal + 140MW gas

Gas

140 MW

Coal capacity MWe 184.4 139 0

Product gas capacity MWe 0 46.3 46.1

Total fuel input MWe 184.4 185.2 46.1

Steam High / Reheat MMlb/hr 1.5 /1.3 1.5/1.35 .35 / .32

Steam temp., High Pressure / Reheat

oF 995 / 1030 995 / 1020 895 / 905

Steam pressure psi(g) 2670 2670 945

Feedwater temp. oF 496 496 412

Reheat stem in temp. oF 617 617 603

Reheat steam in / out psi(g) 618 /581 618 /581 171 / 164

Bolier efficiency % 93.15 92.61 90.56

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Air and flue gas

Coal 100 %

Coal + 140MW gas

Air coefficient (before/after) - 1.196/1.355 1.196/1.364

Total combustion air MMlb/hr 1.75 1.65

Flue gas MMlb/hr 1.91 1.97

Flue gas recirculation MMlb/hr 0 0

Air heater leakage MMlb/hr .233 .232

Flue gas after air heater MMlb/hr 2.14 2.20

O2 before air heater %,wet 3.2 2.9

O2 after air heater %,wet 5.1 4.8

Flue gas temperature after air heater

oF 257 277

Flue gas flow after air heater CFM 636M 678M

Flue gas flow after air heater % 100 106.8

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Flue gas velocities and pressure drops

Coal 100 %

Coal + 140MW gas

Flue gas velocities

- Tertiary Superheater ft/s 36.7 37.4

- Hot reheater ft/s 49.8 50.8

- Cold reheater ft/s 72.5 74.1

- Primary superheater ft/s 60.4 62

- Economizer ft/s 58 60

Flue gas pressure drops

- Furnace Psi 0.014 0.014

- Superheaters Psi 0.12 0.12

- Economizer Psi 0.10 0.11

- Air heater Psi 0.26 0.27

- Total Psi 0.5 0.52

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Production flexibility - Conclusions

Coal and biogas (100% load)

• Boiler performance close to 100% coal firing

• Due to increased flue gas flow there is a need for pressure drop reduction of

approx 0.8-1.0” H2O compared to 100% coal capacity

– Air heater leakage prevention through maintenance and washing

– Removal of flue gas guide vanes in flue gas duct

Biogas only (ultra low load)

• Leads to 350,000 lb/hr high pressure steam (only 23% load)

• It was agreed that this case will be studied further after the main project is

finished

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Operational experiences

• There have been no instabilities in the boiler.

• NOx -emission levels have been under the limits of the

environmental permit (500 mg/m3(n)) – after the modifications

the emission level is around 350 mg/m3, compared to around

400 mg/m3 last year. A decrease of over 10%.

• All performance guarantee values were met.

• The dryer has functioned fine. Investment has proven

successful because biofuels have been abnormally wet this

year.

• The potential risk of the hot corrosion of the superheaters was

noticed and therefore a theoretical study was made by Metso.

As a result it was decided to keep the rate of biofuel always

under the rate of coal.

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Thank You!

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