the role of solid fuel conversion in future power generation

Technische Universität München

The Role of Solid Fuel Conversion in Future

Power Generation

Hartmut Spliethoff

FINNISH-SWEDISH FLAME DAYS 2013

“Focus on Combustion and Gasification Research”

Jyväskylä, April, 17th and 18th 2013


Content

1. Future Developments

1. Worldwide

2. Germany

2. Power Station Requirements

3. Technologies - What Power Plants are required?

4. Research Demand for Solid Fuels

5. IFRF Research

6. EF Gasification Research at TUM


1. Future

Primary Energy – World, New Policies Scenario

IEA, WEO 2011


1. Future

Importance of Coal – Worlwide

IEA, WEO 2012


1. Future

Importance of Biomass – Worlwide

IEA, WEO 2012


1. Future

Energy concept 2010 (Germany) – Power Generation


2. Requirements

Power requirements – Situation Germany 2010

Source: Spliethoff: et. al, CIT 2011

Today (2010): Share of renewables 16 %, Wind 26 GW, PV 17 GW


2. Requirements

Power Requirements – Germany 2020


Requirement for low minimum load

2020: Wind 46 GW, PV 50 GW, Constant consumption


2. Requirements

Power Station Requirements

Efficiency

Investment costs

Flexibility

• Future:

• Operational hours ↓ Investment costs ↓

• Flexibility:

• Start-up time ↓ , minimal load ↓

• Load change capability ↑

• Efficiency ??


3. Technologies

Technologies for the future


- Storage technologies:

- Long term: chemical storage

- Power to heat

- Flexible conventional power generation for balancing

- Combined Cycle the preferred technologies

- Pulverized Coal Power Station with low investment costs

- Integration of storage technologies

- Renewables:

- Biomass

- Waste


3. Technologies

Comparison Flexibility: CC versus PC


Combined

Cycle (new)

Pulverized Coal

Power Station

new old

Load Change 3-6 % / min 3-6 % / min

2-4 % / min

Minimum

load 25 % (2 GT) 20 % 40 %

Start-up

hot (8h)

warm (48 h)

0,5 – 1 h

1- 1.5 h

1-2 h

3 h

2 h

4-5 h


3. Technologies

Ongoing developments - PC


• Reduction minimum load

– Firing stability determines

minimum load:

– Requirement: safe operation in

case of a mill failure

– Bituminous coal: Reduction for

pure coal firing: 35-40 % 20

%

– Brown coal: Reduction from

appr. 50 % to 20 % by predrying

• Operation without power production


3. Technologies

Gasification - challenges and opportunities

Gasification

Efficient CO2-

separation

Chemicals and energy

carriers/ polygeneration

Power Production

(IGCC)

Flexibility in the

context of increasing

renewables

+ High efficiency

- Costly

- Low availability


3. Technologies

Gasification - challenges and opportunities

Chemical

Synthesis • Methanol

• SNG

• FT liquids

Gasifier

Storage

for SNG and FT

fuels

infrastructures

are already

present

Electrolysis

19


3. Technologies

IGCC-EPI: Excess Power Integration

Entrained flow

gasifier

Quench/

HRSG

Synthesis

Gas-

turbine

Electrolysis Gas grid O2-storage ASU H2-storage

HRSG Coal

H2S Exhaust gas

SNG O2 H2

O2

H2

0-100%

0-100% 0-100%

0-100%

50-100%

100%

El.

Energy

El. Energy El. Energy

Steam

turbine cycle Rectisol

Excess power


3. Technologies

Waste

Electrical Efficiency

- Europe, average: 13 %

- new conventional plants: 18 %

Zella Mehlis, Germany


3. Technologies

Biomass

Source: hs energieanlagen gmbh

Biomass CxHyOz

Fluidized bed

gasification

Methanation

SNG

Source: www.skymeshgroup.com

Gas cleaning,

tar, sulphur,…

23

Entrained

Flow

gasification


4. Research Demand

Conversion

Raw coal

H2O Volatiles

Heating/ drying Pyrolysis Char combustion Ash

CO2, H2O Volatiles

combustion

Step De-

mand

Examples

Pyrolysis 2 Kinetics, composition, impact on char structure

Volatile comb. 3 Gas phase combustion

Char

combustion

1 Kinetics for O2, CO2, H2O, char structure and reactivity


4. Research Demand

Emission – Example NOx emission

- Demand: extensive research in the past and secondary measures lower

research demand

- Key: Distribution volatile N and char-N

raw coal

Fuelnitrogen coal char

char

N2

N2

NO

N

Volatiles

Volatil

N

fixedN


4. Research Demand

Ash related issues

- Ash makes the difference to gas

combustion

- Operational problems such as

slagging, fouling and corrosion are

domnination design and operation

- Research demand:

- Ash formation

- Ash chemistry

- ……..

charcombustion

Evaporation

anorganicvapours

NucleationCoagulation

heterogeneouscondensation

fragmentation

Tail cokeparticle

coalparticle

Mineral inclusions

ashparticle

I

superfineparticle(0,1 µm)

II

agglomeratedash particle(0,1 - 10 µm)

III

flyash(1 - 20 µm)


4. Research Demand

Gasification

• Gasification offers a high potential (integration, membranes)

- with CCS η < 40 %

- without CCS η ≤ 50%

• CCS power plant today is based on available technologies

Gasifier Gas

cleaning

High T

shiftLow T

shift

CO2

separation

Coal H2

CO2

Conve

ntio

nal Gasifier Gas

cleaning

High T

shiftLow T

shift

CO2

separation

Coal H2

CO2

Gasifier Gas

cleaning

High T

shiftLow T

shift

CO2

separation

Coal H2

CO2

Conve

ntio

nal

Gasifier Gas

cleaning

Membrane

shift

Coal H2

CO2

Me

mbra

ne r

ea

ctor

Gasifier Gas

cleaning

Membrane

shift

Coal H2

CO2

Me

mbra

ne r

ea

ctor

KEY for future development: Knowledge of coal behaviour including mineral

matter/ trace components at highest temp./ pressures and reducing conditions

• Gasification is an old technology ↔ knowledge base is low


4. Research Demand

Fuel characterization and CFD-modelling

Requirement for design and operation: to know the impact of

- fuel quality and

- combustion conditions

Approach:

• Fuel Characterization: Advanced FC, which consider large scale

combustion conditions

• CFD modelling: data of fuels and ashes required

on

- Combustion behaviour,

- Emissions

- Slagging, fouling and corrosion


• Characterise solid fuels

– to fill data gaps for numerical model validation

& application

– includes fuels that are environmentally and

economically significant

• Biomass, Wastes, Blends with coals

• In atmospheres that reflect O2/RFG

approach, temperatures and pressures of

current interest to members and other

sponsors (steam, CO2)

• Establish protocols for solid fuels

combustion/gasification characterisation

• Produce and maintain DATABASES (IFRF Solid

Fuel Database- http://sfdb.ifrf.net

5. IFRF Research

IFRF - Fuel characterization


• Length 4 m, ID 0.15 m

• 8 modules, 19 feed ports

• quenched collector probe

• 60 kW burner, 54 kW

resistances

• 700-1400°C

• 5-1500 ms residence time

• carrier gas (O2, N2, CO2 mix)

conditions similar to those of

full scale plants

5. IFRF Research

The IFRF Isothermal Plug Flow Reactor (Livorno – Italy)


Issues:

• Temperature is really isothermal?

• Particles residence time

distribution – trajectories

• Partciles actual T vs time history

CFD modeling can help to correctly

analyze and interpretate the raw

data produced by IPFR.

5. IFRF Research

IPFR Qualification:

CFD modeling


• Straw pellets (Denmark)

• Torrefied Spruce (BE 2020)

• Sofwood pellets (BE 2020)

• DDGS (TUD)

• Palm Kernel Shell (+ torrified) (KTH & Poland)

• Lignine (Italy)

• Sunflower seeds (Italy)

5. IFRF Research

Materials


experimental data with error bars and sub-model fitting

5. IFRF Research

IPFR - Conversion versus time/ T, gas composition


6. Gasification Research at TUM

Research Project -

Industry Partner: Siemens, Air Liquide, RWE, EnBW, Vattenfall

Research Partner: TUM, TUB Freiberg, FZ Jülich, GTT

CFD

Simulations

IGCC

Concepts Trace Species

Condensation

Gasification

Kinetics

In-situ

Monitoring



Coal Gasification Kinetics



Experimental Procedure



Pressurized High Temperature EF Reactor (PiTER)

Technical Data

Temperature: up to 1800°C

Pressure: up to 5.0 MPa

Residence time: 0.5 – 5 s

Feed: pulverized coal

Fuel mass flow: up to 5 kg/h

Gas vol. flow: max. 100 mN³/h

Gas composition: N2,H2O,CO2,H2,

O2,CO

Reactor height: 7000 mm

Reaction tube

length: 2200 mm

inner diameter: 70 mm

• Experiments at pressure

• Gasification in CO2/H2O/O2

• Pyrolysis in inert atmospheres

• Char and gas analysis 7 m

1 m



Experimental facilities – Babiter, WMR and PTGA

Optical

ports

Pressurized

heating system

Balance system

PWMR1100°C, 5.0 MPa

Sample

Coal

feederGas

preheater

Heating

zones

Water

quench

Sampling

probeChar

filter

Gas

analysis

PTGA1600°C, 5.0 MPa

BabiTER1600°C, atmospheric

(a) (b) (c)

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6

Tem

pera

ture [

°C]

Time [s]

0.1 MPa

1.0 MPa

2.5 MPa

5.0 MPa



Reaction kinetics in a technical EF Gasifier


Conclusions

• Relative decrease of coal utilization in the medium

and long-term, but absolute increase in the short

and medium term

• Importance of biomass and waste fuels

• Increase of fluctuating renewables requires flexible

power plants

• Research in solid fuels is still required

the role of solid fuel conversion in future power generation

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