mitsui babcock

8/7/2019 Mitsui Babcock

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Mitsui Babcock Biomass Co-firingExperience from the UK


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Who is Mitsui Babcock?

Leading, multi-specialist energy services company

UK based, global operations, 4,500 employees worldwide

A leader in utility coal fired power generation technology,

regular participant in EU and DTI R D and D programmes

Annual turnover approximately 600m, profitable and

sustainable

Established in 1891 as Babcock & Wilcox Ltd formation

of Mitsui Babcock Energy Limited in 1995

Products and services across all fuel types and throughout

the complete plant life cycle


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The Renewables DirectiveA Challenge for the British Power Industry

The Renewables Directive has been key in driving biomass co-firing in the UK

UK like some other EU states allow co-firing to contribute tomeeting targets

Significant Renewable Energy Supply possible where fuel supplyand availability can be successfully integrated with effective co-firing methods

UK co-firing rules allow,- extended co-firing on non-energy crop biomass- But forces a transition to energy crop from 2009

Historical risks,- Poor or expensive fuel supply infrastructure,

- Lack of flexible and robust handling/ combustion technology,- Insufficient legislative and market incentives for co-firing

Successful large scale co-firing demands an integrated approach toovercome these risks


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Overcoming Logisticaland Technical Challenges

In-country Supply- Availability and sustainability

- Extraction, processing and transport costs

- Consistency of quality (moisture and heat value)

- Drying and handling issues

Imported Supply- Significant an sustainable volumes

- Guaranteed quality (low moisture, consistent heat value)

- Transport CO2/cost offset by less drying/handling risks

- Can be cost competitive

Co-firing v Dedicated plant- +50% more RES-E/tonne biomass

- Lower capital cost and project risk


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An Integrated Approach

Co-firing Methods

Technical Risks and

Best Practice

UK Co-firing Experience


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Co-firing Methods

Utility Co-firing of biomass isthe most efficient conversionroute to RES

Co-firing can be achieved by,

- Co-milling

- Dedicated co-firing

Direct Injection

Dedicated burners

Co-firing burners


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Technical Risks and

Best Practice


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Co-milling

Majority of stations co-firing by pre-blending thebiomass with the coal, before the mill

Co-firing ratios typically 5% on a heat input basis.

Minimal effect on boiler performance and environment.

Most of the technical problems associated with thereception, storage and handling

The constraints on the co-firing ratio have been:

- Fuel availability,

- Handling/blending system capacity

- Limitations of the coal milling equipment.


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Co-milling

A range of biomass being co-milled in,- Ball and tube mills

- Vertical spindle ball and

- Ring, and roller mills.

Mill performance depends on brittle fracture ofcoal into particles

Biomass can accumulate in the mill - longer toclear the mill during shutdown.

Mill differential pressure and powertake can increase on vertical spindle mills.

Mill product top-size increases as largerbiomass particles exit the classifier.

Biomass moisture affects mill heat balance

Can be limiting factor (e.g. inadequate drying). Safety issues when co-milling biomass - mill

operating procedures optimisation


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Trend Toward Dedicated Co-firing

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

Establish co-firing by pre-blending and co-milling on the preferredfuel 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 supplyand the co-firing ratio.

Integrate the biomass co-firing into the normal station operations.

Upgrade the biomass reception, storage, handling and blendingfacilities, to increase throughput and reduce mechanical handlingconstraints, dust generation, etc.

Some now implementing direct firing of the biomass to permithigher co-firing ratios.


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Dedicated Co-firing options

The biomass can be pre-milled either off-site or on-site

All direct co-firing systems involve pneumatic conveyingof the biomass from the fuel reception/handling facilityto 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 ofthe biomass into the pulverised coal pipework or burner


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Direct injection

Direct injection through the furnace wall with onlyconveying air and no flame stabilisation.

Demonstrated, on a trial basis, in a downshot-fired

boiler in Britain, Simple and cheap to install,

Limited application for wall or corner-fired boilers.

Only conducted with dry biomass to date

Handling and combustion risks with wetter biomass


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Dedicated Burners

Modified pulverised coal burners or cycloneburners

New burner locations required in rear orside walls.

Secondary air supply requires significantductwork modifications.

New burner locations -Impact on thepulverised coal combustion and the furnaceperformance need assessment

New burner maintainability and controlcould result in generation risk

Dedicated biomass burners have not been

extensively demonstrated commercially onUtility plant.

Complex and relatively expensive to install.


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Co-firing Burners

Demonstrated in Britain and continental Europe.

Injection locations at the mill outlet or local to theburners.

Simple and cheap to install, but implications on the milloperation and control.

The risks of interference with the operation of the coal

firing system needs assessment.

If the biomass is to be injected at the burner, there aresignificant burner modifications required.


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Modified MB Mark III LNB forCoal-Straw Co-firing at Studstrup


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UK Co-firing Experience

All of the coal-fired power plants in Britain are co-firing biomass.

The total number of ROCs (MWh) from biomass co-firing to datealmost 3 million.

The range of biomass materials co-fired includes:

- Wood in a variety of forms, principally sawdust or pellets,

- Imported dry residues from the olive oil and palm oil industries, and- Liquid biomass materials, principally talloil.

Volumes of biomass required are significant e.g.

- 5% Co-firing on a 2GWe plant = 200-300 ktonnes/year(@ 40% load factor)

Low Cost Imported biomass in high volumes has produced themajority of E-RES in the UK


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Renewable Electricity (ROCs)from Co-firing to Sept 05

3,799EdF1,980West Burton

2,868,501Total ROCs/MWh

11,777RWE npower1,085Tilbury

128,089Int. Power1,000Rugeley

20,409E.on UK2,010Ratcliffe

209,420Scottish Power2,400Longannet

168,515E.on UK2,034Kingsnorth

127,681E.on UK970Ironbridge

442,910SSE1,995Fiddlers Ferry

977,172SSE2,035Ferrybridge

10,092British Energy1,960Eggborough

426,218Drax Power4,000Drax

46,351RWE npower2,100Didcot

75,630EdF2,000Cottam

9,302Scottish Power1,200Cockenzie89,744RWE npower1,455Aberthaw

Cumulative ROCsGeneratorCapacity (MWe)Station


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Conclusions

Large Scale co-firing is one of the most efficient and low costmethods in meeting EU RES targets.

Co-milling is being practised by all Coal plant operators

Direct co-firing projects are being developed in British coal-firedpower plants as a means of increasing the co-firing RES.

Injection of the biomass into the existing burner currently appearsto 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 key to profitability.


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[email protected]

www.mitsuibabcock.com

+44 (0) 141 886 4141

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