Process Engineering / GEA Barr-Rosin
BioPro Expo & Marketplace / Atlanta, GA / March 14-16, 2011
Drying of Woody Biomass
Process Engineering / GEA Barr-Rosin
Conventional Direct Fired Dryer Technology
Proprietary work of the Copyright Owner
Process Engineering / GEA Barr-Rosin
Issues with conventional dryers
• Fire and Explosion Risks• Large footprint• Significant leaks at rotary dryer seals use more energy• Energy input is lost to atmosphere• VOC emissions• Require separate thermal oxidizer for gas clean up
Process Engineering / GEA Barr-Rosin
Superheated Steam Rotary Dryer
5
Proprietary work of the Copyright Owner
Process Engineering / GEA Barr-Rosin
Superheated Steam Dryer
6
Cyclone
Screw
DryingLoops
SuperHeater
PC
GeneratedSteam
TC
Backmix
DRYPRODUCT
WET FEED
Mixer
Air Heater
FreshAir
Process Air
Natural Gas
CombustionFan
Exhaust
CleanLP Steam
ReboilerCold-Hot Wateror Condensatefrom another
process
Condensateto Sewer
Proprietary work of the Copyright Owner
Process Engineering / GEA Barr-Rosin
Progression of heat recovery options
FanAir Heater Dryer
M M E M+E
Tamb Tin Tout
M
FanAir Heater Dryer
M E M+E-R
Tamb Tin ToutR
FanAir Heater DryerM
E M+E
Tin ToutM
E Twb> 200o F Heat Exchanger
Open Cycle dryer
Process Gas RecycleDryer
Superheated SteamDryer
Process Engineering / GEA Barr-Rosin
Water Content / Dew Point Dryer Bleed Off
0. 00
10. 00
20. 00
30. 00
40. 00
50. 00
60. 00
70. 00
80. 00
90. 00
100. 00
0 2 4 6 8 10 12
k g H2O / k g dr y a i r
Dew PointTemperature
P a r t i a l Ga s Re c y c l i ng
SSD Rot a r y Dr um
Ope n C i r c ui t D r y e r
SSD Ri ng Dr y e r
Oxygen/ FuelHeated dryer
Process Engineering / GEA Barr-Rosin
Boiler SSD Dryer Combination
Proprietary work of the Copyright Owner
Process Engineering / GEA Barr-Rosin
-
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
0% 10% 20% 30% 40% 50% 60%
mJ/
kg
Moisture
Heat available in wet Fuel
Heat available
I mJ/kg = 430 btu/lb
Basis for Comparison
Process Engineering / GEA Barr-Rosin13
• Biomass Fuel Poplar• Calorific Value (HHV) 20,750 kJ/kg• Feed Moisture 50 %• Combustion air preheat temperature 130 0C• Flue gas exhaust temperature 90 0C• SSD Product Moisture 5 %• Dryer internal pressure 4 bara• Dryer inlet temperature 440 0C• Dryer outlet temperature 130 0C• Isoentropic efficiency of turbines 88 %
Basis for Comparison
Process Engineering / GEA Barr-Rosin
Biomass Boiler Using Wet Fuel
14
~HP Turbine
Condenser0.1 bar
LP Turbine
Economiser
Wet Fuel40.32 t/hr@ 50% moisture
Economiser
HP Steam70 bar
Boiler100 T/hr
Combustion Air
31 mW
Exhaust900C
Process Engineering / GEA Barr-Rosin
Biomass Boiler with SSD Preheating Feedwater
15
~HP Steam70 bar HP Turbine
Condenser0.1 bar
SSD
Superheater
Bleed Offsteam
Dry Productto Fuel Storage
DirtyCondensate
Economiser
Fuel
Combustion Air
Exhaust900C
31 mWBoiler100 T/hr
Wet Fuel35.2 t/hr@ 50% moisture
400 kW
Proprietary work of the Copyright Owner
Process Engineering / GEA Barr-Rosin
Biomass Boiler Generating extra power from SSD
16
~HP Turbine ~
Condenser0.1 bar
LP Turbine
SSD
Superheater
Bleed Offsteam
DirtyCondensate
EconomiserPre-driedFuel
Economiser
Dry Productto Fuel Storage
HP Steam70 bar
Combustion Air
Exhaust900C
31 mW 2.7 mW
Reboiler
Wet Fuel40.32 t/hr@ 50% moisture
Boiler100 T/hr
400 kW
Proprietary work of the Copyright Owner
Process Engineering / GEA Barr-Rosin
Advantages of using Dry Fuel
• Higher net calorific value & efficiency
• Dry fuel is easier to store & meter which gives better combustion control
• Fuel is stable & will not rot in storage
• Less CO2 emissions
• Low Humidity exhaust & lower acid dew point
• Smaller gas cleaning systems
• Lower exhaust volume
• Less visible plume
• If wet sludges are produced on site dryer gives a consistent fuel
Process Engineering / GEA Barr-Rosin
Flexible Fuel solution can burn multiple fuels
• Any organic waste material• Fibre or Bran• Sawdust• Waste wood• Straw• Lignin• Dried sludges municipal & Industrial• Biogas or waste liquid fuel via auxilliary burner
Process Engineering / GEA Barr-Rosin
Dryer for Softwood waste Northern Sweden
SSD Dryer, Skellefteå Kraft,Northern Sweden
for Wood Chips & Sawdust22 ton evaporation/hour
Product for Wood PelletsRecovered steam to Power &
District heating
Inlet %DS t/h C bar kWFeed 50 50 10 - 395Heating steam latent - (33) 250 25 17540Electrical power - - - - 1000Total 50 18935OutletProduct 90 22.8 100 1235Generated steam - 27 145 4.2 17500Heat losses 0.2 100 - 200Total 50 18935
Process Engineering / GEA Barr-Rosin
Dryer for Wood Waste Denmark
SSD Dryer, for Energi E2Located at Jünkers flooring plantin Köge, Denmark for wood pellet production shipped to Avedore Power Plant20 tons/hr evaporation Recovered steam to drying & curing ovens for flooring
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