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Biomass Drying – Commercial Dryers Mediums: - Air - Flue gas - Superheat Steam Rotary dryer Belt dryer Flash dryer Fluidized bed Small particle High corrosion Fire risk after drying Leakage in steam dryer Variable particle sizes Robust Low temperature drying Steam – heat recycle Reasonable dimension Steam – heat recycle Uniform & low temperature High M/H transfer Variable particle sizes Reasonable dimension Robust Larger dimension of dryer Fire risk inside dryer - high hazard risk Corrosion and erosion Blocked by long bark Fire risk after drying Small & uniform particle Abrasion among particles Leakage in steam dryer Advantages Disadvantages
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Page 1: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – Commercial Dryers

Mediums:

-Air

- Flue gas

- SuperheatSteam

Rotary dryer Belt dryer Flash dryer Fluidized bed

Small particle

High corrosion

Fire risk after drying

Leakage in steam dryer

Variable particle sizes

Robust

Low temperature drying

Steam – heat recycle

Reasonable dimension

Steam – heat recycle

Uniform & low temperature

High M/H transfer

Variable particle sizes

Reasonable dimension

Robust

Larger dimension of dryer

Fire risk inside dryer

- high hazard risk

Corrosion and erosion

Blocked by long bark

Fire risk after drying

Small & uniform particle

Abrasion among particles

Leakage in steam dryer

Advantages

Disadvantages

Page 2: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying– Case Study: Evaluation of the Biomass Drying Process

40% flue gas250 oC – 450 oC;647 - 336 t/h

60% hot water90 oC; 737 t/h

Heating Sources

100 MW

Biomass

Heating Sources

40 MW

Drying

Page 3: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – Case Study

Mflue , HCf,in, Tf,in, Hf,in Mflue , HCf,out, Tf,out, Hf,out

Mwood, MCw,in, Tw,in, Hw,in Mwood, MCw,out, Tw,out, Hw,out

Mflue , Tf,,out

Dryer

Mass and Heat Balances:

Flue Gas Drying

MS, Ps,in, Ts,in, Hs,inMwat, Twat, HwatMS, Ps,out, Ts,out, Hs,out

Mwood, MCw,in,

Tw,in, Hw,in

Mwood, MCw,out,

Tw,out, Hw,out

Pre-heater

Dryer

R

Mflue , Tf,in

Mflue , Tf,,out

Steam Drying

Page 4: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – Case Study

Mflue , HCf,out, Tf,out

Mwood, MCw,in, Tw,in Mwood, MCw,out, Tw,out

Mflue , HCf,in, Tf,in

A Continuous Cross-Flow Belt Dryer

Page 5: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – Estimation of Profitability

Flue gas drying

Initial MC=1.5 kg-w/kg-wood

Cumulative cash flow 10 year NPV

Final MC=0.1, 0.3 kg-w/kg-wood Final MC=0.1 kg-w/kg-woodFuel price = 14 €/MWH Fuel price = 14 €/MWH

Page 6: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – Estimation of Profitability

Steam drying

Cumulative cash flow 10 year NPV

Final MC=0.1, 0.3 kg-w/kg-wood Final MC=0.1 kg-w/kg-woodFuel price = 14 €/MWH Fuel price = 14 €/MWH

Page 7: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – Estimation of Profitability

Effect of fuel prices

Initial MC=1.5 kg-w/kg-wood

Final MC=0.1 kg-w/kg-wood

10 year NPV

Page 8: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Bacho industryKirkenaerMEC companyMitchell Dryers Ltd

Rotary

Belt

Flash

GEA; DryCo; Einco

Flue gas150-700 C

* 10000-26000 kg/h** 3.7 MJ/kg-H2O

Steam150 C

* 6000-30000 kg/h** 0.4-1.0 MJ/kg-H2O

Fluidized Bed

Niro A/S

Steam190 C

* 3600 kg/hFlue gas160-280 C

* 800-7000 kg/h

**5.8 MJ/kg-H2O

Cost (not including

Biomass Drying – commercial dryers

* Evaporation rate of water ** Heat consumption

Belt

Swiss Combi, Bruks Klöckner, Mabarex, Andritz Fiber

** 0.4-1.0 MJ/kg-H2O

Air30-110 C

* 500-40000 kg/h

Cost (not includingInstallation):$22-106 /kg/h Including installation-$300-796 /kg/h ,$1.6-5.3 millionfor 15-130 MW bioler;-$761 /kg/h$ 5.4 millionfor 55 tonnes/h boiler

Cost (excluding installation)

$ 18-160 /kg/h

Including installation

-$335/kg/h, 180tonnes/h

burning bark

-$550-1600 /kg/h

$ 3.5-10.6 million

for 15-130 MW boiler

Page 9: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Biomass Drying – other options

Advantages:- high power density-reducing drying time- high energy efficiency, avoid warm up and cool down- improved quality, compared with conventional drying.- avoids combustible gas by- products, environmental friendly

Disadvantages:- not uniform dried (hot spot or cold spot)- penetration achievable, depended on biomass properties.- insufficient knowledge of the interaction between wood

Microwave dryer

- insufficient knowledge of the interaction between wood and process parameters as well as the higher investment expenses.

Supercritical CO2Advantages: - using CO2(green house gas)- low temperature (saving energy)- low fire risk- high quality (avoiding high temperature heating biomass)

Disadvantages:- high pressure equipmentand processes

Page 10: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Task3 Task3 -- Sheffield ; high efficiencySheffield ; high efficiency

l Novel technology

l Industrial condensing boilers

l Low temperature, < dew point

l Boiler design

l External system

Page 11: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Condensing boilersCondensing boilersl Benefits:

– High efficiency: recovery of sensible and latent heat

– Emission reduction: absorption by the condensate

Dew point

Dew point

Re-vaporisation of the condensate

Page 12: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Condensing boilersCondensing boilersl Application/Case Studies

– Oriketo heating station in Finland (Condenser: 12MWth)

– Vimmerby Energy AB in Sweden (Condenser: 2MWth)

– CHP power plant in Harnosand, Sweden (11 MWe, 26MWth, Condenser: 7MWth)

– Nitrate Stress Corrosion Cracking in Waste Heat Recovery Boilers in the Netherlands in 1990’s (Leferink et al. 2003)

» Ammonia Nitrate» Ammonia Nitrate

» Carbon steel and low alloy steel are sensitive to attack

Oriketo heating station

Page 13: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Condensing boilers with Radiator & floor heatingCondensing boilers with Radiator & floor heating

l Return water from a heating system should be 30-50°C, well below the dew point of flue gas

l A floor heating system or large surface area radiator is required.

Page 14: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Condensing boilers with a heat pumpCondensing boilers with a heat pump

l A heat pump can be used between the condenser and the hot return water– Conventional electrically driven compression heat pump

– An absorption heat pump

Page 15: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...
Page 16: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Thermoacoustic EngineThermoacoustic Enginel Thermoacoustic engines of which nearly all are thermoacoustic

stirling engines;

l It is a technology that uses high-amplitude sound waves in a pressurized gas to pump heat from one place to another;

l or uses a heat temperature difference to induce sound, which can be converted to electricity with high efficiency, with a (piezoelectric) loudspeaker;(piezoelectric) loudspeaker;

l The most efficient thermoacoustic devices built to date have an efficiency approaching 40% of the Carnot limit, or about 20% to 30% overall (depending on the heat engine temperatures).

Page 17: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Thermoacoustics Engine Thermoacoustics Engine (Standing (Standing --wave)wave)

Stack Total power

Acoustic power

Standing-wave engine example, Scale drawing, and power distribution of Tektronix researchers (G. W. Swift, 2002)

Branch to refrigerator

InsulationAmbient heat exchanger

Stack

Hot heat exchanger138 cm

Branch

Page 18: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Thermoacoustics Engine Thermoacoustics Engine (Traveling(Traveling--wave)wave)

Tapered pulse tube

Regenerator

Traveling-wave refrigerator example, Schematic and power distribution: Cryenco 2-kW orifice pulse-tube refrigerator (G.

W. Swift, 2002)

Acoustic power

Total power

Page 19: Biomass Drying –Commercial Dryersresearch.ncl.ac.uk/pro-tem/components/pdfs/Sheffield_PRO_TEMJan... · Rotary dryer Belt dryer Flash dryer Fluidized bed ... Microwave dryer ...

Thermoacoustic Engine (Malone Thermoacoustic Engine (Malone Refrigeration)Refrigeration)

Thermoacoustic refrigeratorThe Sonic Compressor


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