Workshop on - European Commission...Workshop on Biomass Co-processing and co-firing Arranged by: ... (Laborelec) started his presentation by explaining the option of biomass pre-gasification

Workshop on

Biomass Co-processing and co-firing

Arranged by:

Gerrit Brem and Jaap Koppejan TNO Science and Industry, Netherlands

April 5, 2006 Crowne Plaza Hotel, Lille, France

2

ThermalNet workshop Biomass Co-processing and co-firing

April 5, 2006, Lille, France

Table of contents

Programme........................................................................................................... 3

Report of the workshop ...................................................................................... 4

Introduction - Gerrit Brem................................................................................................. 4

Direct combustion - Bill Livingston, Mitsui Babcock ...................................................... 4

Gasification - Frans van Dijen, Laborelec......................................................................... 5

Pyrolysis - Wolter Prins, BTG............................................................................................ 5

Torrefaction – Harold Boerrigter, ECN............................................................................ 6

Discussion ............................................................................................................................. 6

Annexes

Annex 1. Introduction Gerrit Brem

Annex 2. Direct combustion Bill Livingston, Mitsui Babcock

Annex 3. Gasification Frans van Dijen, Laborelec

Annex 4. Pyrolysis Wolter Prins, BTG

Annex 5. Torrefaction Harold Boerrigter, ECN

Annex 6. Discussion

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Programme

April 5, 2006, 11:30 – 13:00 Crowne Plaza Hotel, Lille, France

From Topic

11:30 Introduction - Gerrit Brem, TNO

11:40 Direct combustion - Bill Livingston, Mitsui Babcock

11:55 Gasification - Frans van Dijen, Laborelec

12:10 Pyrolysis - Wolter Prins, BTG

12:25 Torrefaction – Harold Boerrigter, ECN

12:40 Discussion

13:00 Closing

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Report of the workshop

Introduction - Gerrit Brem Gerrit Brem, coordinator of WP2B (Co-processing and Co-firing) introduced the aims of this workshop. Biomass can be co-processed with several different existing processes and through various concepts: both direct combustion, gasification, pyrolysis and torrefaction are processes currently being examined for possible application in cofiring and co-processing. Though direct cofiring with the primary fuel is often the most straightforward and cost-effective way to replace a primary fuel, there may be certain negative impacts on plant operation that make this option unattractive. Examples are - Limited fuel flexibility of the boiler or biomass fuel specs outside of range - Incomplete combustion and insufficient mixing in boiler - Fouling and corrosion of the boiler (alkalis, chlorine) - Ash utilization (unburnt carbon, contamination) - Negative impact on flue gas cleaning (SCR DeNOx) According to an inventory made by IEA Bioenergy Task 32, some 135 plants that originally fire coal as main fuel have experience with co-firing biomass. The overwhelming majority of these plants do this directly over the existing fuel conveyors and milling lines, but an increasing number of plants also has experience with thermal pretreatment routes such as gasification. The aim of this workhop is to provide an overview of the merits of the various routes and to get an impression for which types of biomass and power plants these could be applied.

Direct combustion - Bill Livingston, Mitsui Babcock Bill Livingston (Mitsui Babcock) presented some of his company’s experience with direct cofiring, with emphasis on the situation in UK. All of the coal power stations in Britain are co-firing biomass up to 6% heat input, predominantly by pre-blending the relatively dry biomass in the coal yard. Various types of biomass are cofired, such as wood sawdust and pellets, imported dry residues from the palm oil and olive oil industries, cereal pellets, and liquid biofuels. The main technical limitations on the cofiring ratio are related to the capacity of the handling/blending systems and the performance of the coal mills, which again depends on the type of biomass and type of mills. Operational problems that may occur when co-milling biomass are related to the high volatile content of biomass that may cause fire hazard if hot primary air is used, the high moisture content of biomass disturbing the mill heat balance, larger top size of biomass particles leaving the mill and increased mill power consumption and pressure drop. If co-milling is not an option, separate biomass mills may be installed, after which the pulverised biomass is fed either to the fuel lines before the existing coal burners or to new biomass burners. Most experience with direct cofiring exists with injecting pulverised biomass after the existing mills and before the existing burners. Placement of new dedicated

5

burners in the furnace rear or side walls may increase combustion performance of the biomass, but it is typically an expensive, complex and relatively risky operation as compared to modifying existing burners. There is some experience with dedicated burners, e.g. at Hasselbyvaerket in Sweden and Ferrybridge in UK. Disadvantages are the impact on operational flexibility during low load operation and for mill maintenance, the need for additional fuel and air supply lines, interference on mechanical and control interfaces. Finally, cofiring may have a significant impact on ash behaviour as biomass ash has a very different chemical composition from coal ash. This may lead to high temperature corrosion, increased ash deposition, increased stickiness of the ash through its lower ash melting point, increased aerosol emissions and affect options for fly ash utilization. Finally, the availability of sufficient biomass that can be directly cofired is often a critical issue when developing a direct cofiring project.

Gasification - Frans van Dijen, Laborelec Frans van Dijen (Laborelec) started his presentation by explaining the option of biomass pre-gasification at one of the existing pulverised coal units of Ruien, Belgium. This plant is basically a copy of the existing ACFB gasifier in Lahti, Finland as also supplied by Foster Wheeler. The biomass fuel (mainly wood, depending on moisture content between 40-80 MW of fuel input) is gasified in the atmospheric CFB gasifiers and then directly fired into the coal furnace. Specific investment costs are in the range of 500-1000 Euro/kWe. The operational performance of the gasifier is satisfactory. Electrabel already uses over 1 Mtons of biomass per year, mainly dry wood. Key R&D issues are related to grinding biomass/coal for direct cofiring and the fuel flexibility of power plants. One promising concept Electrabel is currently working on is biomass-cofiring in a large scale USC CFBC installation. Another R&D priority is the development of separate biomass pulverised fuel lines, including reception, storage, purification, and hammer mills plus screens. Frans van Dijen also presented his ideas on the future perspective for large scale biomass/coal combustion. Although Electrabel has developed and implemented various cofiring concepts successfully and in good cooperation with local authorities, it is uncertain what will be needed after 2012 (when the Kyoto obligations end). Legislation is often poor or complex and environmental aspects are often hard to tackle.

Pyrolysis - Wolter Prins, BTG Wolter Prins (BTG) presented the results of a cofiring trial for pyrolysis oil which was carried out in the 350 MW natural gas fired power plant of Harculo, Zwolle, the Netherlands. Pyrolysis oil was cofired through one of the oil lances. This way some 30 tons of pyrolysis oil were cofired on a single day. The test was considered successful, operators noted no difference in thermal behaviour of the boiler. It is however uncertain how the boiler would react if pyrolysis oil would be cofired for a longer term. Being a liquid, advantages for cofiring pyrolysis oil are the ease of handling and integration into the existing process operation. Critical issues that might limit application potential are the low pH of the oil and the heating value which is relatively low in comparison to fossil oil.

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Torrefaction – Harold Boerrigter, ECN Harold Boerrigter (ECN) presented some key aspects of the torrefaction process which is currently under development. By torrefying wood or other biomass and eventually pelletising the product, both grindability and volumetric energy density of the fuel significantly improve, making it easier and cheaper to transport and handle the material and feed it into an existing pulverised coal power plant. The lower heating value doubles from approx 10 MJ/kg to approx 20 MJ/kg and through the optional pelletisation, the volumetric energy density can even triple. Particularly when biomass handling and shipping costs become a significant portion of the price of delivered fuel, torrefaction can be a cost attractive alternative.

Discussion In the discussion that followed, the options for the different pre-treatment routes were compared. It was concluded that direct cofiring is by far most commonly applied, but there are some options for the other pre-treatment routes as well. This is shown in the below table: Biomass characteristics Power plant type Grindability Contaminations Pulverised coal boilers Fluid bed boilers Natural gas boilers Natural gas turbines

Low Direct, Torrefaction Direct Pyrolysis, Gasification

Pressurised gasification

Good

High Gasification Direct or gasification+gas cleaning

Gasification Pressurised gasification

Low Gasification, Torrefaction

Direct Gasification Pressurised gasification

Poor

High Gasification Direct or Gasification+gas cleaning

Gasification Pressurised gasification

Some specific conclusions drawn were - Pyrolysis oil could be used in natural gas or potentially also oil fired boilers and for start

up of coal power plants. Firing pyrolysis oil in gas turbines is not (yet) an option. - The current regulatory situation in the UK makes it relatively difficult to apply indirect

cofiring concepts through pre-gasification. This has to do with the large capital expenditure requirements and the cap on cofiring ROCs.

- The presence of alkali chlorides in combustion gases of some particular biomass species affects opportunities for direct cofiring in some cases. It might then be more attractive to pre-gasify the biomass and remove the chloride before firing the gas in the coal furnace.

Annex 1. Introduction, Gerrit Brem

1

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TNO Science and Industry

Biomass co-processingcombustion, gasification, pyrolysis, torrefaction

Gerrit Brem and

Jaap Koppejan

ThermalNet Workshop

April 5th 2006, Lille, France

ThermalNet workshop/Co-processing/G. Brem and J. Koppejan

Workshop

• Co-processing – possible concepts?

• Technology overview (presentations by experts)

• Discussion

2

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Biomass co-firing (concepts)

• Direct co-combustion in coalfired power plants

• Indirect co-combustion withpre-gasification

• Indirect co-combustion in gas-fired power plants

• Pre-treatment by torrefaction

• Parallel co-combustion (steamside coupling)


Technical barriers

• Fuel flexibility (quality, quantity)

• Incomplete combustion and insufficient mixing in boiler

• Fouling and corrosion of the boiler (alkalis, chlorine)

• Ash utilization (unburnt carbon, contamination)

• Negative impact on flue gas cleaning (SCR DeNOx)

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Overview of biomass co-firing initiatives

• Recently done by IEA Bioenergy Task 32

• Internet database produced at www.ieabcc.nl

• 135 plants identified that co-fire biomass in plants that

originally fire coal as main fuel

• 105 direct, 1 parallel, 5 indirect, 24 yet unknown


Selection criteria for the co-processing technologies?

• Biomass properties (classification)

• State-of-the-art of the technology

• Costs €/MWth and €/MWh

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Workshop Co-processing11:30 Introduction - Gerrit Brem11:40 Direct combustion - Bill Livingston, Mitsui Babcock11:55 Gasification - Frans van Dijen, Laborelec12:10 Pyrolysis - Wolter Prins, BTG 12:25 Torrefaction – Harold Boerrigter, ECN12:40 Discussion13:00 Closing

Annex 2. Direct combustion Bill Livingston, Mitsui Babcock

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Biomass Co-firing W R Livingston, Mitsui Babcock

Presented toThermalnet, Lille

April 2006

Biomass co-firing in Britain• All of the coal power stations in

Britain are co-firing by pre-blending the biomass with the coal, at up to 6% heat input.

• The range of biomass materials has included:

Wood, principally as pellets and sawdusts,Imported dry residues from the palm oil and olive oil industries,Cereal pellets, and Liquid biofuels

• The co-firing has had a modest impact on boiler performance and environment.

• The principal constraints on the co-firing ratio have been:- Fuel availability,- Handling/blending system capacity,

and - Limitations on the co-firing ratio

imposed by the coal mill.

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Recent experience in Britain

The general approach at a number of British stations has been asfollows:

• Establish biomass co-firing by pre-blending and co-milling on the preferred fuel, at minimum capital cost and with short project lead times.

• Obtain the Environmental License Variation for commercial co-firing activities.

• Modify the Variation to permit greater flexibility in the fuel supply and the co-firing ratio.

• Integrate the biomass co-firing into the normal station operations.• Upgrade the biomass reception, storage, handling and blending

facilities, to increase throughput and reduce mechanical handling constraints, dust generation, etc.

• Consider the direct firing of the biomass to permit higher co-firing ratios.

Cumulative Co-firing ROCs (MWh) Feb.06

45,127Alcan420Alcan Lynmouth

64,677EdF1,980West Burton

4,102,805Total ROCs/MWh

25,946RWE npower1,085Tilbury252,085Int. Power1,000Rugeley37, 501E.on UK2,010Ratcliffe269,915Scottish Power2,400Longannet237,113E.on UK2,034Kingsnorth135,740E.on UK970Ironbridge606,864SSE1,995Fiddlers Ferry

1,246,550SSE2,035Ferrybridge140,778British Energy1,960Eggborough748,527Drax Power4,000Drax50,303RWE npower2,100Didcot

124,431EdF2,000Cottam25,958Scottish Power1,200Cockenzie

91,290RWE npower1,455Aberthaw

Cumulative ROCsGeneratorCapacity (MWe)Station

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Co-milling of biomass • A range of biomass materials are being co-

milled in,- Ball and tube mills- Vertical spindle ball and- Ring, and roller mills.

• Mill performance depends on brittle fracture of coal particles.

• Biomass materials are not subject to brittle fracture.

• Biomass can accumulate in the mill - longer times to clear the mill during shutdown.

• Mill differential pressure and power take can increase on vertical spindle mills.

• Mill product top-size increases as larger biomass particles exit the classifier.

• Biomass moisture affects mill heat balance – Can be limiting factor for high moisture biomass.

• There are safety issues when co-milling biomass - mill operating procedures may require modification.

Safety issues when co-milling biomass in large vertical spindle coal mills

• The key issue in mill safety is avoiding hot primary air coming into direct contact with dry fuel.

• This is particularly important during certain mill operations such as planned shutdowns, emergency shutdowns and restarts after emergency shutdowns, loss of coal or intermittent coal feed incidents, etc.

• Biomass has high volatile matter content and combustible volatiles are released in significant quantities at temperatures above about 180ºC, i.e. at much lower temperatures than for bituminous coals.

• It is usually advisable to reassess and modify the mill operating procedures to allow the co-milling of biomass safely.

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Dedicated direct co-firing options

• The biomass can be pre-milled either off-site or on-site• All direct co-firing systems involve pneumatic conveying

of the biomass from the fuel reception/handling facility to the boiler house.

• There are three basic direct co-firing options:- Direct injection into the furnace with no combustion air,- New, dedicated biomass burners, and - Co-firing with coal through the existing burners by injection of

the biomass into the pulverised coal pipework or burner.

Dedicated Burners

• Modified pulverised coal burners or cyclone burners

• New burner locations required in the furnace rear or side walls.

• Dedicated biomass burners have not been extensively demonstrated commercially on Utility plant.

• Complex and relatively expensive to install.

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The installation of dedicated biomass burners

• Additional, dedicated burners are required for the biomass firing, and this can impact on operational flexibility during low load operation and for mill maintenance.

• The dedicated biomass burners are not well demonstrated for this type of application.

• 100% biomass (wood pellet) firing through MB axial swirl burners has been demonstrated at Hasselby in Sweden, >10 years operating experience.

• The fuel supply and air supply systems for the biomass burners have to be installed, and there are mechanical and control interfaces with the boiler.

• The impacts of the exposure of the new biomass burners, when out of service, to the coal-fired furnace have to be assessed.

• Overall, the installation of dedicated burners is an expensive and relatively high risk approach to biomass co-firing.

Direct injection to the installed coal firing system

• Demonstrated in Britain and continental Europe.• Injection locations at the mill outlet or local to the burners.• Simple and cheap to install, but there are implications on the

mill operation and control.• The risks of interference with the operation of the coal firing

system need assessment.• If the biomass is to be injected at the burner, there are

significant burner modifications required.• Recent demonstration of a direct firing system in Britain. The

system has been in successful operation since summer 2005, firing pre-milled biomass.

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The direct biomass co-firing system

• The fuel is wood biomass, pre-milled to < 5 mm, at moisture contents less than 30%, metered and conveyed pneumatically to the boiler.

• The injection point is in the mill outlet pipes, just downstreamof the product dampers. The injection point is a simple shallow angle T-in, fitted with an actuated shut-off valve for the biomass,

• The mill air and fuel flow rates have to be reduced in line withthe biomass conveying air flow rate, and the heat input to the mill group from the biomass.

• Both the mill and the burners are maintained within their normal operating envelopes, for both the heat input and primary air flow rate. The maximum heat input from the mill group is not affected.

• The mill is operated on full automatic control when the biomass co-firing system is in service.

• There are new interfaces between the mill and biomass conveying system controls, covering permits to operate, biomass system shutdowns, start-ups and trips, etc.

Studstrup coal-straw burnerModified MB Mark III LNB

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Biomass ash effects• Most biomass materials have relatively low ash contents (<5%),

compared to most power station coals.• The biomass ashes are very different chemically from coal ashes, i.e.

they are not an alumino-silicate system, but a mixture of simple inorganic compounds, of Si, K, Ca, P and S.

• Three basic biomass ash types have been described:- High Si, high K, low Ca ashes, with low ash fusion temperatures, e.g.

many agricultural residues,- Low Si, low K, high Ca ashes, with high fusion temperatures, including

most wood materials, and- High Ca, high P ashes with low fusion temperatures such as most

manures. • There are concerns about increased rates of high temperature

corrosion of boiler components, with high chlorine biomass materials.

• Biomass co-firing tends to increase the level of submicron aerosols and fume in the flue gases and may impact ESP collection efficiency.

• There may be utilisation/disposal issues with mixed coal/biomassashes.

The effect of biomass ash on Ash Fusion Temperatures and fouling behaviour

• For high fusion temperature coals, the addition of relatively small amounts of some biomass ashes can reduce the DT by as much as 200ºC.

• For low fusion temperature coals, the effect is much less dramatic.

• For predictive purposes, normal coal Slagging Indices can be applied.

• Empirical correlations permit estimation of the Deformation Temperatures of mixed ashes.

• Fouling indexes for mixed ashes are based on alkali metal contents.

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Conclusions

• Large scale biomass co-firing is one of the most efficient and low cost approaches to generating electricity from renewable sources.

• Biomass co-milling is being practised by all coal plant operators in Britain.

• Direct co-firing projects are being developed in British coal-fired power plants as a means of increasing the co-firing ROCs.

• Injection of the biomass into the installed coal firing system currently appears to be the optimal direct firing solution.

• Project risk increases with,- Co-firing Ratio- Fuel quality and diversity

• Integration of co-firing technology selection with low cost fuel supply in high volumes is the key to profitability.

Annex 3. Gasification Frans van Dijen, Laborelec

1

LABORELECTitle / Reference © LABORELEC – 9-Feb-06 – 1

25/07/2006BIOMASS GASIFICATION RUIENFrans van Dijen© LABORELEC


INTRODUCTION

CONTENTS� INTRODUCTION�GASIFICATION�GASIFIER�CHANGES

2


INTRODUCTION

�Copy of Lahti, Finland�Supplied by Foster Wheeler�Fuel : biomass only, mainly wood�Wood is young coal and coal is old wood

(roughly)


GASIFICATION

�Gasification : 2C6H10O5 (+ 2H2O) + O2 =12CO + 10H2 (+ 2H2O)

�Temperature too low => more air => more oxidation => ca. 800 °C

�Air flow constant : control of temperature by variation of fuel flow : more fuel = reduction of temperature

3


GASIFIER

�Atmospheric pressure, using air, circulating fluidised bed

�No gas purification�Hardly gas cooling�So, is direct co-combustion�CFD modelling of boiler by Laborelec /

University of Stuttgart�Capacity 40 to 80 MW of fuel, depending on

moisture content of 50 to 10 wt.%�Specific project costs of 500 to 1000 €/kWe.


GASIFIER

4


CHANGES

�From wet wood to dry wood : doubling the capacity expressed in MW of fuel

�Mechanical purification of fuel added�Operating personnel and fuel purchasers

who are familiar with the technology is of advantage !

�Control of temperature with dry wood needs attention

� In general we are happy with the gasifier !�For the Gelderland power plant we planned

doubling the capacity with 1 gasifier


5



6



7


Five reasons for you to choose Laborelec :

� You have one-stop shopping for your energy related services

� You get access to more than 40 years of experience

� You increase the profitability of your installations

� You benefit from independent and confidential advice

� You are supported by a recognized and accredited laboratory

LABORELEC

The technical Competence Centrein energy processes and energy use.From R&D to operational assistance.

1


25/07/2006TRENDS WITH BIOMASS WITHIN ELECTRABELFrans van Dijen© LABORELEC


INTRODUCTION

CONTENTS� INTRODUCTION�TRENDS WITHIN ELECTRABEL�R&D�REMARKS ON POLICIES AND

STRATEGIES

2


TRENDS WITHIN ELECTRABEL

�Focus on power generation� Increasing quantities : > 1,000,000 ton DM

per year in 2006� Increasing quality : dry wood� Low investments : What after 2012 ?�Co-combustion and conversion to 100%

biomass combustion� Investing in R&D


R&D

�Dedicated grinding of coal and biomass : wear, power consumption, type of mill

�Co-grinding of coal and biomass : using coal mills, operations, power consumption

�Fuel flexibility of power plants � Large scale USC CFBC (about 600 °C, 300

bars, 700 MWe and no addition of limestone to the bed). Specific extra project costs of 100 €/kWe for (co-)combustion of dry wood pellets and/or chips.

3


R&D, USC CFBC, LAGISZA


R&D, DEDICATED GRINDING OF DRY WOOD

�Reception, storage, purification, hammer mills plus screens, no storage of pulverised fuel

�< 40 kWhe/ton� 100% < 1 x 3 mm²�Specific project costs of ca. 300 €/kWe

4


R&D,(CO-)GRINDING USING COAL MILLS


REMARKS ON POLICIES AND STRATEGIES

�Good co-operation with local authorities (B, NL, PL)�Excellent biomass concepts (B)�Absence of long term strategy (BE, NL, UK, EU,

Electrabel)� Long term strategy lacks IQ (D)�What after 2012 ? (B, NL)�Poor quality legislation (NL, B, EU)�Experienced opponents (NGO’s) (NL)�Complex legislation (D)�Environment is hardly a topic (B, NL)

5


Five reasons for you to choose Laborelec :

� You have one-stop shopping for your energy related services

� You get access to more than 40 years of experience

� You increase the profitability of your installations

� You benefit from independent and confidential advice

� You are supported by a recognized and accredited laboratory

LABORELEC

The technical Competence Centrein energy processes and energy use.From R&D to operational assistance.

Annex 4. Pyrolysis Wolter Prins, BTG

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1

Bio-oil co-combustion

350 MW Natural gas fired power plant Harculo, Zwolle, the Netherlands

2


Stack Power plant Harculo

2

3


Bio-oil container (produced March - combustion Sept) and Pumping system

Bert Wagenaarhimself

His shoes

4


Burner gallery of three burners

3

5


Burner lance set-up

6


Gas and bio-oil burners Feed rate 2 tonnes/hour NG

Bio-oil

4

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Bio-oil co-combustion in practice (movie)

Annex 5. Torrefaction – Harold Boerrigter, ECN

1

Biomass Pre-treatmentby Torrefaction

Third ThermalNET Meeting, 3-5 April 2006, Lille, France

Harold Boerrigter, Jaap Kiel, Patrick BergmanEnergy research Centre of the Netherlands (ECN)ECN Biomass, Coal & Environmental Research

(2) ECN Biomass, Harold Boerrigter Torrefaction, Third ThermalNET Meeting, Lille, France, 3-5 April 2006 www.ecn.nl

Roasting

Mild PyrolysisPre Pyrolysis

High T drying

mild thermal treatment

Wood cooking

Wood browning

?????

TorrefactionVarious definitions

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Torrefaction

mass energy

gas

biomass solids1 0.7

0.3

1 0.9

0.1

0.70.9 = 1.31Energy densification (E/kg)

Temperature: 200-300 °C

Pressure: near atmospheric

Heating rate: <50 °C/min

Absence of oxygen

Product: solid phase (energy)

Residence time 30 to 90 min

Particle size < 4 cm thickness

TorrefactionGeneral process description


Tough and fibrous10 to 17 MJ/kg (LHV, ar)Hygroscopic, Hydrophilic

Vulnerable to biodegradation Contaminated Heterogeneous

Friable and less fibrous 19 to 22 MJ/kg (LHV, ar)

HydrophobicPreserved

Reduced contaminations Homogeneous

Torrefaction andpulverisation

Pelletisation

Waste

TOP fuel pellets

Demolitionwood

Green biomass

Size reductionCombustion / Gasification

Logistic operations (transport)

Feedstock bandwidth Biofuel standardisation

TOP fuel powder

750-850 kg/m3

15-20 GJ/m3

+ + +

++

+

TorrefactionProduct quality of torrefied biomass

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Properties unit Wood T orrefied biomasslow high low high

M oisture content % w t. 35% 3% 10% 7% 5% 1%C alorific v alue (LH V)

dry M J/kg 17.7 20.4 17.7 17.7 20.4 22.7as receiv ed M J/kg 10.5 19.9 15.6 16.2 19.9 21.6

mass density (bulk) kg/m3 550 230 500 650 750 850energy density (bulk) GJ/m3 5.8 4.6 7.8 10.5 14.9 18.4Pellet strength - -Dust formation moderate high limited limited

H y groscopic nature w ater uptake hy drofobic

B iological degradation Possible ImpossibleSeasonal influences (noticable for end-user)

H igh Poor

H andling properties normal normal

Wood pellets T OP pellets

good

sw elling / w ater uptake

v ery good

poor sw elling / hy drofobic

Possible

M oderate

good good

Impossible

Poor

TorrefactionComparison of (torrefied) biomass and (TOP) pellets


0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.0 0.2 0.4 0.6 0.8

(O/C)

(H/C

)

TW(250)

TW(260)

TW(270)

TW(275)

TW(280)

TW(285)

Wood (dry)

Charcoal

Coal/peat

Biomass becomes like peat !

peat

TorrefactionVan Krevelen Diagram

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-

10

20

30

40

50

60

70

80

90

- 0.5 1.0 1.5

average particle size (mm, volume based)

Pow

erco

nsum

ptio

n(k

We/

MW

th)

C(270,21)

C(280,18)

C(290,12)

W(290,24)

W(260,24)

Willow (MC=10-13%)

Willow (dried)

Cutter w ood

AU bituminous coal

Borssele run

demolition w ood

D(300,11)

TorrefactionGrindability improvement (experimental results)


Drying Torrefaction Cooling

Heat exchange

BiomassTorrefiedbiomass

Air

utillity Fuel

Flue gas

Combustion

∆P

Torrefactiongases

Flue gas

Flue gas

Gasrecycle

Moving bed based reactor technology

Compact reactor

Accurate T-control

Feedstock flexibility

Low capital investment

Small footprint

High capacity

Torrefaction TechnologyECN directly heated torrefaction process

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TOP process (South Africa)

Logistics

ConventionalPelletisation

(South Africa)Logistics

Co-firing of TOP pellets in existing

coal fired power stationsNorth-West Europe

Sawdust

Sawdust

2.0 EUR/GJ0.7 EUR/GJ 2.0 EUR/GJ

4.7 EUR/GJ

2.2 EUR/GJ0.7 EUR/GJ 2.9 EUR/GJ

5.8 EUR/GJ

30-70%SavingsTorrefaction aids …

Economics!

Torrefaction Economics Change study: TOP pellets vs. conventional pellets


Dr.ir. Jaap Kiele: [email protected] t: +31 224 56 4590w: www.ecn.nl

P.O. Box 1NL 1755 ZG Pettenthe Netherlands

For further informationPlease, contact:

Annex 6. Discussion

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Short term suitability of different thermal pretreatment routes

Pressurisedgasification




Natural gas turbines

Gasification

Direct,Gasification

Gasification

Direct

Fluid bed boilers

Power plant typeBiomass characteristics

GasificationGasification, Torrefaction

LowPoor

GasificationGasificationHigh

GasificationGasificationHigh

PyrolysisGasification

Direct, TorrefactionLow

Contaminations

Good

Grindability Natural gas boiler

Pulverised coal boilers

Documents

Workshop on - European Commission...Workshop on Biomass Co-processing and co-firing Arranged by: ... (Laborelec) started his presentation by explaining the option of biomass pre-gasification