The Current State of Austrian Pellet Boiler Technology

Transcription

1 he Current State of ustrian ellet Boiler echnology ngwald Obernberger Gerold hek S U S Y G R B BOMSS S H C O O M Y BOS BORGSYSM GmbH Sandgasse 47, Graz,, ustria.: +43 (316) ; FX: +43 (316) M: office@bios-bioenergy bioenergy.at HOMG:

2 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz ntroduction ustrian pellet market Standards for pellet furnaces ellet combustion technology Feeding Storage Burn-back protection Basic burner principles echnical details (furnace geometry, materials, control systems, boiler technology, de-ashing) missions Future developments

3 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Development of small-scale scale pellet furnaces in ustria umber of newly installed pellet central heating units 5,000 4,000 3,000 2,000 1,000 0 Source: [ower ustrian Chamber for griculture and Forestry, 2002] ,536 3,041 4, Year feed from storage tank feed from storage room

4 R G Y S H B BOMS S O C O M Y ellet production [1,000 t/a] BORGSYSM GmbH Sandgasse 47, Graz Source: [Geisslhofer, 2000: Wood pellets in urope; own enquiries] ellet production in ustria present state and outlook * 2010* *different prognoses for the year 2010 Year

5 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz ellet consumption in ustria (year 2001) bout 12,300 pellet central heating systems already installed in ustria otal nominal boiler capacity installed: about 220 MW nnual utilisation rate: about 72 % Boiler full load operation hours: 1,500 h p.a. et calorific value of pellets: 4.9 kwh/kg pellets ellet consumption in ustria approximately 94,000 t/a ellet export about 22 % of annual production: 26,000 t/a

6 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz General framework in ustria nvestment subsidies granted in ustria on average 25 % (depending on the ustrian provinces) Currently 12 pellet producers active in ustria ellet quality regulated by ÖORM M 7135 and the standard of the ustrian ellets ssociation Quality of pellet furnaces regulated by ÖORM Supply of pellets in ustria assured throughout the country by a well organised distribution network bout 30 manufacturers of small-scale pellet furnaces in ustria

7 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Standards for furnaces fired with pellets ustria: ÖORM Sweden: SCR 093 S-Method 2453 parameter ÖORM SCR 093 S-Method 2453 valid for heating boilers with a nominal boiler capacity up to 300 kw 15 kw testing required by law + - pellets are the only permitted fuel - + all solid fuels (biomass and fossil fuels) are permitted + - maximum organic carbon (OGC) emission [mg/mj CV ] maximum CO emission [mg/mj CV ] maximum O x emissions [mg/mj CV ] maximum dust emissions [mg/mj CV ] 60 - minimum combustion efficiency * 75% limited validity period for the certificate - 2 years *depending on the nominal boiler capacity (see following slide)

8 R G Y S H B BOMS S O C O M Y 88 BORGSYSM GmbH Sandgasse 47, Graz Minimum combustion efficiency according to ÖORM Combustion efficiency [%] combustion efficiency [%] = boiler heat produced fuel heat input (CV) ominal boiler capacity [kw] manual feed automatic feed

9 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz ellet central heating systems ellet combustion systems ellet single stoves ellet burners Source: [R Metallwarenges.m.b.H. & Co G, ustria] Source: [GUMC Heiztechnik GmbH, ustria] Source: [Gilles nergie und Umwelttechnik GmbH, ustria]

10 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Feeding and storage systems used Feeding systems Screw conveyor (inflexible) Screw conveyor (flexible) neumatic system neumatic system / screw conveyor combination gitator / screw conveyor combination Storage systems Storage room (83 %) ntegrated store (17 %) Underground storage tank

11 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz gitator / screw conveyor combination Motor for conveying screw Screw conveyor gitator Source: [WB raft und Wärme aus Biomasse GmbH, ustria, 2002]

12 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Burn-back protection systems (1) Cellular wheel sluice Fireproof valve Source: [COMC Heiz- und nergie-systeme GesmbH, ustria] Source: [WB raft und Wärme aus Biomasse GmbH]

13 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Burn-back protection systems (2) xtinguisher system Fall shaft Source: [nton der GmbH, ustria] Source: [GUMC Heiztechnik GmbH, ustria]

14 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Basic principles of wood pellet burners Underfed burners Horizontally fed burners Overfed burners Source: [Handbook of Biomass Combustion and Co-Firing,, 2002]

15 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Underfed burner Boiler with spiral scrapers ntermediate storage Flue gas Secondary air Conveying screw Retort Fan rimary air sh box Fuel supply (stoker screw) Source: [WB raft und Wärme aus Biomasse GmbH, ustria, 2002]

16 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Geometry of the combustion chamber important parameters ir staging Mixing of secondary air and flue gas (position and design of the secondary air nozzles) ppropriate dimensioning of primary and secondary combustion zone (residence time) Good utilisation of the furnace volume (flow distribution) ven temperature distribution (furnace temperature control)

17 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz ir staging and optimised mixing between flue gas and secondary air Secondary combustion zone Secondary air rimary combustion zone rimary air Source: [GUMC Heiztechnik GmbH, ustria]

18 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Design and optimisation of the nozzles for the injection of secondary air and re-circulated flue gas Vectors of the flue gas velocity [m/s] in the horizontal cross-section right over the secondary air nozzles Basic nozzle design mproved nozzle design CFD-based furnace and nozzle design of great relevance Source: [BOS BORGSYSM GmbH, ustria, 2002]

19 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Materials used for combustion chambers material price heat storage capacity corrosion resistance deposit resistance stainless steel firebrick silicon carbide low / expensive +...medium ++...high / cheap

20 R G Y B BOMS S S H O C O M Y oad control BORGSYSM GmbH Sandgasse 47, Graz Guiding value: feed water temperature Variables: fuel and primary air feed Control systems Combustion control Guiding value: O 2, CO or O 2 and CO concentration in the flue gas (lambda, CO or CO/lambda control) Variable: secondary air supply emperature control Guiding value: temperature in the combustion chamber Variables: flue gas recirculation or water-cooled furnace walls ressure control Guiding value: pressure in the combustion chamber Variable: induced draught fan (frequency)

21 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz CO [mg/m 3 ] CO-λ-characteristic and influencing parameters 10 4 increased fuel water content partial load Source: [Good, H Zürich, 1992] ambda [-]

22 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Boilers Geometry Usually vertical fire tube boilers (one or three-pass boilers) Boiler cleaning Fully automatic by spiral scrapers in the fire tubes Semi-automatic by spiral scrapers in the fire tubes with a lever from the outside Manually utomatic boiler cleaning systems increase the efficiency and reduce dust emissions

23 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Fully automatic boiler cleaning system Source: [BOS BORGSYSM GmbH, ustria, 2002; furnace of WB - raft und Wärme aus Biomasse GmbH]

24 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz De-ashing systems Usually ash collection in an ash box ash box must be emptied periodically sh compaction systems partly applied ash box must be emptied periodically in longer periods of time Fully automatic de-ashing system by a screw conveyor in an external container ash box must be emptied only about once a year

25 B S S BOMS Y G R BORGSYSM GmbH Sandgasse 47, Graz sh compaction system C O O M Y S H Compactor sh box Source: [WB raft und Wärme aus Biomasse GmbH, ustria, 2002]

26 BORGSYSM GmbH Sandgasse 47, Graz B S S BOMS Y G R missions (500) Source: Spitzer et al, 1998; B Wieselburg, C O O M Y S H CO OC Ox (O2) dust test stand measurements field measurements limiting value mission factor [mg/mj (CV)]

27 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz CO emissions comparison between old and new pellet furnaces 300 CO [mg/mj] Source: Jungmeier et al, 1999; B Wieselburg, 2002; results from test stand measurements

28 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Dust emissions comparison between old and new pellet furnaces Source: Jungmeier et al, 1999; B Wieselburg, 2002; results from test stand measurements Dust [mg/mj]

29 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz OC and Ox emissions comparison between old and new pellet furnaces OC (total organic carbon) o differences detected due to the generally low level of the organic carbon emissions Ox (nitrogen oxides) Ox emissions depend on the fuel nitrogen content (no thermal Ox formation) no clear trends detected Ox reduction by primary measures possible (depends mainly on air staging, residence time and temperature of the flue gas in the primary combustion zone)

30 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Future developments CFD-aided furnace development and optimisation Medium-scale combustion systems (nominal boiler capacity up to 500 kw th ) Reduction of particulate emissions Small-scale dust burners (utilisation of pulverised pellets) Utilisation of herbaceous / non-woody biomass fuels Combination of pellets with solar systems Small-scale CH systems (e.g. Stirling engines)

31 R G Y S H B BOMS S O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Stirling engine application for small-scale scale pellet furnaces el : 1.1 kw lectric efficiency: 23 % Service life: 40,000 hours Fired by wood pellets 10 plants in operation (pilot plants) Source: [Sunpower nc., US, 2001]

32 R G Y B BOMS S S H O C O M Y BORGSYSM GmbH Sandgasse 47, Graz Summary Rapidly expanding pellet market in ustria Several actors, quality standards and subsidies supporting this development roven feeding and combustion technologies available from many furnace manufacturers which ensure a fully automatic operation ow emissions with a decreasing tendency for new furnaces Several research activities and promising developments focusing on new fields of application, new biomass fuels and emission reduction