advanced oxy-fuel combustion technology

© Babcock Hitachi k.K.. 2009. All rights reserved.

Contents 1. Background and Objective 2. Advanced oxy-fuel combustion system (Gas cooler system) 3. Development of new burner for oxy-fuel combustion 4. Erosion and fouling risk 5. Summary

Advanced Oxy-Fuel Combustion Technology Toshihiko Mine1), , Kenji Kiyama1), Yuji Fukuda1), Noriyuki Imada1), Pauli Dernjatin2)

1) Kure Research Laboratory, Babcock-Hitachi K.K. 2) Power Division, Fortum Power and Heat

3rd Oxyfuel Combustion Conference (September 10,2013)

1

1.1 CCS Technology Development Trend and Hitachi Vision

- Coal firing is currently the leading source of power generation - Hitachi has been developing two key technologies of CO2 capture from coal fired power plants; “CO2 Scrubbing”, “Oxy-fuel Combustion” and high efficiency technologies of “700C A-USC”, “ IGCC”

2010 2015 2020 2030 2025 Regulation

Road of Development

Hitachi Vision of

Technology Development

Capture Ready Partial Reduction Full

Reduction Pilot Testing Plant Demonstration

Plant Commercial Plant Ultimately-

Clean Plant

CO2 Scrubbing

700℃ A-USC Efficiency of 46%(HHV)

Oxy-fuel Combustion

Chemical Looping

700℃ A-USC + CO2 Capture

-High Efficiency -Zero Emission

IGCC + CO2 Capture

2

SCR

AH Mill

Boiler

Boiler High radiation intensity: CO2, H2O -same boiler for air and oxy -risk of erosion and fouling

Liq.CO2

stack O2

Fan

ESP FGD CPU

ASU -reduce initial cost -reduce power consumption compact & low power

ASU

CPU -reduce corrosion potential (SO3, Hg, Cl etc) -reduce power consumption compact & low power

1.2 Development Subjects in Oxy-fuel Combustion

AQCS: Air Quality Control System

ASU: Air Separation Unit CPU: CO2 Compression and Purification Unit

Cooler

AQCS -keep SCR,ESP,FGD performance -installation of gas cooler

Burner -stable operation -low p'ry O2 concentrations

Gas Cooler System -decreasing flue gas temperatures at the ESP inlet -reduce corrosive substances : SO3,Hg

3

2. Advanced oxy-fuel combustion system (Gas cooler system)

Advanced Oxy-Fuel Combustion Technology

4

Condition SO2 [ppm] SO3 [ppm] Hg [µg/m3N] Air Combustion 2,000 30 10 Oxy-fuel Combustion 10,000 180 40

Hg absorbing tower

ASU

ESP

SCR

FGD CPU

Boiler Percentage of gas re-circulation:75％

2.1 Subjects of Gas Re-Circulation in Oxy-fuel Combustion

Boiler exit corrosive substances are concentrated by recirculation under condition of Oxy-fuel combustion

Gas Re-circulation line

5

Gas re-circulation

ASU ESP Cooler

SCR Boiler

FGD CPU

Adsorbed SO3 mist

SO3 (Gas) Ash 160 deg-C

90 deg-C (< acid dew point)

Finned tube

2.2 Mechanism of SO3 Removal

- Below acid dew point, SO3 in flue gas change to mist - Mist sticks to ash and is neutralized by alkali contained in ash and caught by ESP

1.0

0 SO3 C

once

ntrati

on [-

]

ESP Outlet

SCR Outlet

FGD Outlet

ESP Inlet

Location of cooler without Cooler(160 deg-C) with Cooler(90 deg-C)

6

Flue gas treatment total system

O2 Tank

Furnace

2.3 1.5MWth Test Facility (Verification of Flue Gas Treatment)

This study was partly carried out under contract with New Energy and Industrial Technology Development Organization(NEDO) of Japan.

Gas cooler (Finned tubes)

7

2.4 Result of 1.5MWth Test

Measurement point

Gas re-circulation

ASU ESP Cooler

SCR Boiler

FGD

CPU

SO3 can be reduced under 1ppm with 90 deg-C cooler system Hg removal through the overall system is about 85%

With Cooler (90 deg-C)

Without Cooler (160 deg-C)

0

10

20

30

40

0.2ppm SO3 a

t ESP

outle

t [pp

m]

Hg re

mova

l effic

iency

[%]

20

40

60

80

100



carbon steel sulfuric acid resistance steel



40

30

20

10

0 <1 mg/cm2

Corro

sion R

ate [m

g/cm2 ]

(A)

(B)

Test condition - Coal : High sulfur coal (S=2.7%) - Moisture content in flue gas :30-40%

Test condition - Coal : Bituminous coal (Hg=198µg/kg) - Moisture content in flue gas :30-40%

(A) (C) (B)

(C)

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2.5 Features of Hitachi Oxy-fuel Combustion System (500MWe Class Power Plant)

(1) SO3 and Hg removal with 90 deg-C cooler (2) LP turbine power increases because cooler preheats feed water. (Improvement of plant net efficiency : 1.5 points)

1282MW

Boiler ESP

Burner

SCR IDF

Mills

PAF

Coal Oxygen

FGD

GGH

Hot Air

Cooler

FDF

CO2

Stack

SCAH

ASU

CPU (1) (2) +3MW

-60MW

+18MW TB GE

90deg-C

Gas Heater

This study was partly carried out under co-research with FORTUM OYJ.

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3. Development of new burner for oxy-fuel combustion


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Burner flame becomes unstable by change of gas composition (N2⇒CO2)

Mechanism of Flame Spread Photographs of burner flame (4MWth test facility)

Item Air Combustion Oxy-Combustion

Flue gas composition

CO2

H2O O2

N2

CO2 O2

Coal particle

Direction of flame spread

Flame spread speed in Oxy-fuel combustion is lower than that of air combustion because of gas heat capacity is increased.

Air Combustion (Pry O2=21%)

Oxy-fuel Combustion (Pry O2=21%）

3.1 Subjects of Oxy-fuel Combustion Burner

H2O

Radiation

11

PC Concentrator

Coal and Primary gas (Low O2=10%)

Secondary gas

O2 rich gas Supply nozzle

Low

O2 rich gas (O2>30%)

High Gas temp.

Primary O2=10%

NR-LE Burner

NR-3 Burner

O2=21%

Flame is stable at low primary O2

3.2 Results of Numerical Analysis

NR-LE burner can realize stable combustion under low Pry O2 concentration

12

Typical test conditions - Coal type : Bituminous

3.3 4MWth Test Facility (Verification of Flame Stability of Burner)

This study was partly carried out under co-research with FORTUM OYJ.

Cyclone

Burner

O2

AH

IDF

Stuck

Coal feeder Coal 400kg/h

Water Sprayer

GRF

FDF PAF

GC

・Gas Monitor （O2，CO2，CO，NOx，SO2）・UBC Sampling

・FEGT

Furnace

13 12:00 12:30 13:00 13:30 14:00 14:30 15:00 15:30 16:00 16:30 17:00 17:30 18:00 18:30 19:00 19:30

1200 1000

800 600 400 200

0

Time[-]

FEGT

(deg

-C)

Coal

Flow

Rat

e(kg

/h)

O2 F

low

Rate

(m3 N

/h) 0

10

20

30

40 50

O2 (v

ol%

,dry

)

Coal in Air comb. Oxy-fuel comb. Air to Oxy Oxy to Air

Primary O2

Secondary O2

Secondary O2

Primary O2

Exit O2

Coal Flow FEGT (Furnace Exit Gas Temperature)

0 100 200 300 400 500 600

Switching time from air to oxy-fuel combustion ; 30min Flame is stable during switching from air to oxy-fuel combustion

3.4 Result of 4MWth Test(1) ; Operation Stability

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3.5 Result of 4MWth Test(2) ; Flame Stability

NR-3 burner b. Pry O2=24%(wet) c. Pry O2=21%(wet) a. Pry O2=28%(wet)

NR-LE Burner b. Pry O2=10%(wet) a. Pry O2=21%(wet) c. Pry O2=5%(wet)

Stable Stable Unstable

Stable Stable Unstable

Primary O2 content can be reduced to 10% with a new burner (NR-LE) even under unexpected O2 control conditions

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4. Erosion and fouling risk


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4.1 Erosion and Fouling Risk ; Erosion

-Recirculation gas is taken from the outlet of ESP in Hitachi’s system. -Ash content of the gas stream is the same for air combustion and oxyfuel combustion. -Erosion rate will not change between air combustion and oxyfuel combustion.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 200 400 600 800 ash concentration (g/m3)

Ero

sion

rat

e, E

(um

/h)

Effect of ash concentration on erosion rate Ash erosion test equipment

17

4.2 Erosion and Fouling Risk ; Fouling

Tube Ash deposition

Ash deposition rate is the same for both cases of air and oxyfuel combustion.

Typical test conditions - Coal type : Bituminous

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4. Summary

Hitachi has developed a new system for oxy-fuel combustion. Features of this system include: (1) SO3 and Hg removal by decreasing flue gas temperatures at the ESP inlet with a cooler

system.

(2) There is a large increase power of LP turbine output because the gas cooler preheats boiler feed water and reduces steam extraction from LP turbine.

(3) Stable combustion under low O2 concentration of primary gas with NR-LE Burners is achieved.

(4) Erosion and fouling potential must be same to air combustion because ash concentration of oxy-fuel combustion is same to that of air combustion.

We are ready to apply highly efficient and reliable technologies for oxy-fuel combustion to actual projects.

advanced oxy-fuel combustion technology

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