Drying of Woody Biomass. Process Engineering / GEA Barr-Rosin

Transcription

1 Drying of Woody Biomass BioPro Expo & Marketplace / Atlanta, GA / March 14-16, 2011

2 Drying of Woody Biomass

3 Conventional Direct Fired Dryer Technology Proprietary work of the Copyright Owner

4 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

5 Superheated Steam Rotary Dryer Proprietary work of the Copyright Owner 5

6 Superheated Steam Dryer Clean LP Steam Generated Steam Reboiler PC Cold-Hot Water or Condensate from another process Condensate to Sewer TC Cyclone Drying Loops Fresh Air Combustion Fan Exhaust Process Air Super Heater Backmix WET FEED Mixer Natural Gas Air Heater DRY PRODUCT Screw Proprietary work of the Copyright Owner 6

7 Progression of heat recovery options M M E M+E Air Heater Dryer Fan Open Cycle dryer T amb T in T out M M E M+E-R Air Heater Dryer T amb T in T out R Fan Process Gas Recycle Dryer Air Heater M T in M E Dryer M+E T out Fan Superheated Steam Dryer Heat Exchanger E Twb> 200 o F

8 Water Content / Dew Point Dryer Bleed Off Partial Gas Recycling SSD Rotary Drum Open Circuit Dryer Oxygen/ Fuel Heated dryer SSD Ring Dryer Dew Point Temperature kg H2O / kg dry air

9 Boiler SSD Dryer Combination Proprietary work of the Copyright Owner

10 Comparisons of burning wet & dry Fuel

11 Typical Biomass Properties 11

12 Basis for Comparison Heat available in wet Fuel mj/kg Heat available % 10% 20% 30% 40% 50% 60% Moisture I mj/kg = 430 btu/lb

13 Basis for Comparison Biomass Fuel Calorific Value (HHV) Poplar 20,750 kj/kg Feed Moisture 50 % Combustion air preheat temperature C Flue gas exhaust temperature 90 0 C SSD Product Moisture 5 % Dryer internal pressure 4 bara Dryer inlet temperature C Dryer outlet temperature C Isoentropic efficiency of turbines 88 % 13

14 Biomass Boiler Using Wet Fuel Exhaust 90 0 C Economiser Combustion Air Wet Fuel % moisture Boiler 100 T/hr HP Steam 70 bar HP Turbine ~ 31 mw LP Turbine 0.1 bar Condenser Economiser 14

15 Biomass Boiler with SSD Preheating Feedwater Exhaust 90 0 C Economiser Combustion Air Fuel Boiler 100 T/hr HP Steam 70 bar HP Turbine ~ 31 mw 0.1 bar Condenser Dirty Condensate 400 kw Bleed Off steam Superheater SSD Wet Fuel % moisture Dry Product to Fuel Storage Proprietary work of the Copyright Owner 15

16 Biomass Boiler Generating extra power from SSD Pre-dried Fuel Boiler 100 T/hr Exhaust 90 0 C Economiser HP Steam 70 bar Combustion Air 31 mw 2.7 mw HP Turbine ~ ~ LP Turbine 0.1 bar Condenser Reboiler Economiser 400 kw Superheater Bleed Off steam SSD Wet Fuel % moisture Dry Product to Fuel Storage Dirty Condensate Proprietary work of the Copyright Owner 16

17 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

18 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

19 Dryer for Softwood waste Northern Sweden SSD Dryer, Skellefteå Kraft, Northern Sweden for Wood Chips & Sawdust 22 ton evaporation/hour Product for Wood Pellets Recovered steam to Power & District heating Inlet % DS t/h C bar kw Feed Heating steam latent - (33) Electrical power Total Outlet Product Generated steam Heat losses Total

20 Dryer for Wood Waste Denmark SSD Dryer, for Energi E2 Located at Jünkers flooring plant in Köge, Denmark for wood pellet production shipped to Avedore Power Plant 20 tons/hr evaporation Recovered steam to drying & curing ovens for flooring

21 Dryer for Sawdust Super-heated Steam Dryer, Techwood BV, Netherlands Sawdust for composite profiles, 2 ton/h From 85% up to >99% dryness