biomass drying –commercial...
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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
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
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
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
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
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
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
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
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
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
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
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
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.
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
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).
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
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
Thermoacoustic Engine (Malone Thermoacoustic Engine (Malone Refrigeration)Refrigeration)
Thermoacoustic refrigeratorThe Sonic Compressor