technical considerations on biomass fired boilers for heat and power - research in chec, dtu weigang...

Technical considerations on biomass fired boilers for heat and power - Research in CHEC, DTU

Weigang Lin

CHEC Research CenterDepartment of Chemical and Biochemical EngineeringTechnical University of Denmark

2 DTU Chemical Engineering, Technical University of Denmark

Outline

• Brief introduction of DTU Chemical Engineering and CHEC research center

• Problems in biomass fired boilers• Fundamental studies

–Deposit–Corrosion–Aerosol emissions–Counter measures–Gasification

• Concluding remarks


DTU Chemical Engineering:

Lyngby


CHEC Research Center

• New and Fundamental knowledge on• High Temperature Processes• Formation and Reduction of Harmful Components and

Particulates• Catalysis and Chemical Product Design

• To assist enterprises and governmental organisations

• To train engineers and researchers

• To catalyze international cooperation

Combustion and Harmful Emission Control (CHEC)


Development of CHEC

2000

Time

2010

Acidification Debate

1990

Coal

Fluid Bed

SO2

NOx

Bio-mass

Alkali

Corrosion-depositions

Models

Cement

Waste

Products

Coatings

Catalysis

Gasification

Pharma

Minerals

Merger Risø

Systematic development of experimental methods and modeling tools

Focus on Reaction Engineering, Transport processes

New pilot


CHECKDJ

CombustionPGl

GasificationUBH

Fuel Pretreatment

JA

DiognosticsSC

InorganicsFF

CatalysisAJ

Products and Pharma

SK

Project coordination

JBI

Technique, Pilot facilities

PAJ

SDC CoordinationWL

CHEC Organization


New MSc Programme Started in China

A full MSc programme on chemical and Biochemical Engineering, with focus on Biomass, is launched in Beijing, China. The programme offers Danish and Chinese students the possibility of obtaining a dual degree from DTU and the University of Chinese Academy of Sciences (UCAS).


Problems in firing of biomass


Main reason for the problems

KCl Ash deposition

Bed agglomeration

Corrosion

SCR deactivation

PM2.5


K-S-Cl Chemistry in Straw-Fired Systems:

K in straw

KCl/KOH (g)

K-Ca-silicates in bottom ash

KCl/K2SO4 nucleation/

heterogeneous condensation

K2SO4 (g)

SO2

Cl in straw

HCl (g)

Cl in bottom ash

HCl emission

KCl (g) SO2

K2SO4 (g)

S in straw

SO2 (g)

S in bottom ash

SO2 emission

K2SO4 (g) (+

HCl)

KCl / KOH


Deposit Formation:Layered structure:

cm

> 0.7

100% KCl


Measuring Campaigns at Grate Boilers:Fly Ash and Deposit Chemistry• Haslev and Slagelse CHPs (probe), 1994 • Rudkøbing CHP (probe + mature), 1995• Masnedø CHP (probe + mature), 1996-1997, 2000-2002

• Maribo-Sakskøbing CHP (mature), 2001, 2004

• Probe deposits: short term [~ 2-10 hours] exposure of cooled probes (finger print chemistry)

• Mature deposits: In-boiler, long term [~ 103 hours] exposed deposits (real chemistry, including chemical reaction sintering)


Measuring Campaigns at Grate Boilers

Maribo-Sakskøbing boiler Rudkøbing boiler

Haslev boiler Slagelse boiler


Deposit Chemistry


Boiler wall

Probe

Superheaters

CCD camera

Flue gas flow

New, advanced probe:

- Heat transfer

- Mass of deposits

- Temperatures (flue gas and probe)

- Video – visible and IRAfter 3 hr


Corrosion


Corrosion induced by Deposit


Selective Cl-Corrosion: Influence of Methal Temperature

Metal temperature


Aerosol (PM2.5) emissions


Main mechanisms for formation of aerosols during biomass combustion

From van Loo and Koopejan (2002).


Aerosol in a Straw-Fired Boiler


Effect of Additives on Aerosol Mass Loading in a Straw-Fired Boiler:

mg/Nm3

mg/Nm3

dAero, nm

dAero, nm

Ca-P

S


• Aerosol sampling: before SCR unit, T=350oC

• Deposit probe measurement: location B, T= 780±20 oC

• Deposit probe measurement: location A, T= 1275±50 oC

Aerosol emission in Avedøre unit 2

Damø et al. (2014), Wu et al. (2013)


Mass-based particle size distribution of aerosols

• Significant reduction of submicron aerosol formation with addition of coal fly ash

• Similar effect for the addition of 6 ton/h and 3 ton/h coal fly ash Damø et al. (2014)


Possible counter measures to reduce the risk of the problems

+

Co-combustion

Pretreatment

Boiler modification

Boiler SCR ESP

Boiler ESP SCR

Additives

+


Gasification


Two Stage Pilot Plant at Weiss A/S

1:1 1:10

DTU Chemical Engineering, Technical University of Denmark

(LT-CFB) PyroneerDONG Energy Asnæsværket

Low Temperature Circulating Fluid Bed (LT-CFB)


Concluding remarks

• Cl, K and S cause severe operational problems in biomass fired boilers for heat and power production, especially deposition, corrosion, agglomeration and aerosol emissions

• Co-firing biomass and coal can significantly reduce the operational problems

• Application of right additives may be the other solution

• Biomass to power through gasification

Thanks for the Attention

technical considerations on biomass fired boilers for heat and power - research in chec, dtu weigang...

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