Austrian pellet boiler technologies state-of art, ecological evaluation and future developments

Transcription

1 ustrian pellet boiler technologies state-of of-the- art, ecological evaluation and future developments Dipl.-ng. Gerold hek rof.dipl.-ng.dr. ngwald Obernberger S U S Y G R B BOMSS S H C O O M Y BOS BORGSYSM GmbH nffeldgasse 21b, Graz, ustria.: +43 (316) ; FX: +43 (316) M: office@bios-bioenergy.at bioenergy.at HOMG:

2 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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 2

3 R G Y S H B BOMSS O C O M Y umber of newly installed pellet central heating units BORGSYSM GmbH nffeldgasse 21b, Graz 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0 Source: [ower ustrian Chamber for griculture and Forestry, 2005] 425 1,323 2,128 3,466 Development of small-scale scale pellet furnaces in ustria 4,932 4,492 5,193 6, Year feed from storage tank feed from storage room 3

4 R G Y S H B BOMSS O C O M Y ellet production [1,000 t/a] * estimate 1,400 1,200 1,000 BORGSYSM GmbH nffeldgasse 21b, Graz Source: [Geisslhofer, 2000: Wood pellets in urope; own enquiries] ellet production in ustria present state and outlook , * 2009* Year 4

5 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz ellet consumption in ustria (year 2004) bout 28,000 pellet central heating systems already installed in ustria otal nominal boiler capacity installed: about 520 MW nnual utilisation rate: about 74% Boiler full load operation hours: 1,500 h p.a. et calorific value of pellets: 4.9 kwh/kg (w.b.) ellet consumption in ustria approximately 216,000 t/a (related to pellet central heating systems) dditional amounts related to pellet stoves and medium-scale pellet furnaces (100 to 1,000 kw th ) Difference to production: mainly export 5

6 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz General framework in ustria nvestment subsidies granted in ustria on average 25 % (depending on the ustrian provinces) Currently 18 pellet producers active or near start-up in ustria ellet quality, transport and storage regulated by ÖORM M 7135, M 7136 and M 7137 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 6

7 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Standards for furnaces fired with pellets ÖORM parameter value valid for heating boilers with a nominal boiler capacity up to 300 kw testing required by law yes all solid fuels (biomass and fossil fuels) are permitted yes maximum organic carbon (OGC) emission [mg/mj CV ] 40 maximum CO emission [mg/mj CV ] 500 maximum O x emissions [mg/mj CV ] 150 maximum dust emissions [mg/mj CV ] 60 minimum combustion efficiency * *depending on the nominal boiler capacity (see following slide) 7

8 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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 8

9 R G Y B BOMSS S H O C O M Y ellet stoves BORGSYSM GmbH nffeldgasse 21b, Graz ellet central heating systems ellet combustion systems Grate fired pellet boilers for medium-scale applications (150 to 300 kw th ) Source: [R Metallwarenges.m.b.H. & Co G, ustria] ellet burners Source: [Gilles nergie und Umwelttechnik GmbH, ustria] Source: [GUMC Heiztechnik GmbH, ustria] Source: [WB raft und Wärme aus Biomasse GmbH, ustria] 9

10 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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 (88 %) ntegrated store (12 %) Underground storage tank 10

11 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Screw conveyor (inflexible) Motor for conveying screw Conveying screw Screw channel Source: [WB raft und Wärme aus Biomasse GmbH, ustria, 2002] 11

12 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Underground storage tank 1 ellet storage 2 Manhole pit 3 Filling connections Discharge 5 Duct 6 arthing Sucker 8 Dust separator 9 Burner Source: [Stefan au GmbH & Co. G, Germany, 2002] 6 12

13 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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

14 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Burn-back protection systems (2) xtinguisher system Motor Storage Water level switch Water tank Conveying screw from storage hermal burn-back protection storage evel switch hermocouple fall shaft Conveying screw to burner Source: [nton der GmbH, ustria] Valves Motor hermal burn-back protection burner 14

15 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Basic principles of wood pellet burners Underfed burners Horizontally fed burners Overfed burners Source: [Handbook of Biomass Combustion and Co-Firing,, 2002] 15

16 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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

17 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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

18 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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

19 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Design and optimisation of the nozzles for the injection of secondary air Vectors of the flue gas velocity [m/s] in the horizontal cross-section right over the secondary air nozzles Basic nozzle design CFD-based furnace and nozzle design of great relevance Source: [BOS BORGSYSM GmbH, ustria, 2002] mproved nozzle design 19

20 R G Y B BOMSS S H O C O M Y oad control BORGSYSM GmbH nffeldgasse 21b, 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) 20

21 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Relevance of automatic control systems articles <1 µm [mg/m³] CO, org. C [vppm] , CO Corg 13:30 13:40 13:50 otes: Data related to the current operating conditions Change of load from 40% part load to nominal load mportance of automatic control systems to guarantee low CO, OC and particulate emissions at all load conditions (start-up, shut-down, load changes, full and part load operation) 21

22 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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 22

23 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Fully automatic boiler cleaning system Source: [BOS BORGSYSM GmbH, ustria, 2002; furnace of WB - raft und Wärme aus Biomasse GmbH] 23

24 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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 24

25 25 B S S U BOMSS Y G R BORGSYSM GmbH nffeldgasse 21b, 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 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz missions mission factor [mg/mj (CV)] (500) Source: Spitzer et al, 1998; B Wieselburg, 2002 CO OC Ox (O2) dust test stand measurements field measurements limiting value 26

27 R G Y S H B BOMSS O C O M Y 300 BORGSYSM GmbH nffeldgasse 21b, Graz CO emissions comparison between old and new pellet furnaces CO [mg/mj] Source: Jungmeier et al, 1999; B Wieselburg, 2005; results from test stand measurements

28 R G Y S H B BOMSS O C O M Y 60 BORGSYSM GmbH nffeldgasse 21b, Graz Dust emissions comparison between old and new pellet furnaces Dust [mg/mj] Source: Jungmeier et al, 1999; B Wieselburg, 2005; results from test stand measurements

29 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Fine particulate emissions new pellet furnaces bout 90 to 95% of the total dust emissions are fine particles (< 1 µm) Fine particulate emissions from modern pellet furnaces usually have a mass mean diameter of about 0.15 µm f combustion is complete about 1.5 x 10 7 particles per cm 3 are formed complete burnout of the flue gas is very important to minimise fine particulate emissions he chemical composition of the fuel strongly influences fine particulate emissions 29

30 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Fine particulate emissions influence of the fuel composition 10,000 particles <1µm [mg/m³] 1, softwood hardwood waste wood bark straw 100 1,000 10, ,000 total from, a, Zn, b, S and Cl in the fuel [mg/kg d.b.] xplanations: missions related to dry flue gas and 13 vol.% O 2 ; d.b.... dry basis; results from measurements at grate furnaces with nominal capacities between 400 kw th and 50 MW th 30

31 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz Future developments CFD-aided furnace development and optimisation Medium-scale combustion systems (nominal boiler capacities between 100 and 1,000 kw th ) Reduction of particulate emissions (especially M1) Small-scale dust burners (utilisation of pulverised pellets) Utilisation of herbaceous / non-woody biomass fuels Combination of pellets with solar systems ellet furnaces with flue gas condensation Small-scale CH systems (e.g. Stirling engines) 31

32 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz ellet furnace with flue gas condensation flow First pellet boiler with flue gas condensation Market introduction: 2004 return fficiency: 103% (according to type test by B Wieselburg) ominal capacities: 8, 10, 15 and 20 kw flue gas path Source: [ÖkoF, ustria, 2004] 32

33 R G Y S H B BOMSS O C O M Y BORGSYSM GmbH nffeldgasse 21b, Graz ew small-scale scale CH technology based on Stirling engines for wood chip and pellet furnaces 2 pilot plants in operation 35 kw el and 70 kw el Start-up: nd of 2002 (35 kw el ) and nd of 2003 (70 kw el ) Operating hours: > 12,000 (35 kw el ) > 4,000 (70 kw el ) lectric plant efficiency : approximately 11 to 12% Fuels: ellets, wood chips, sawdust First small series production (7 plants with 35 kw el ) Comprehensive field tests ongoing (2005/06) Source: [BOS BORGSYSM GmbH; MWR Holzfeuerungsanlagen GesmbH, ustria, 2005] 33

34 R G Y B BOMSS S H O C O M Y BORGSYSM GmbH nffeldgasse 21b, 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 34