of-the-art of small-scale scale biomass combustion with respect to fine particulate emissions Country report from Austria

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1 g tate-of of-the-art of small-scale scale biomass combustion with respect to fine particulate emissions ountry report from ustria rof. Dr. ngwald bernberger nstitute for rocess ngineering Graz niversity of echnology.: +43 (316) 4813; FX: +43 (316) : bioenergy.at HG: bios-bioenergy.atbioenergy.at R G g H R G H nstitute for rocess ngineering Graz niversity of echnology ontents Residential heating systems in ustria he ustrian state-of-the-art of biomass based residential heating systems missions from residential biomass heating systems onclusions and recommendations 2

2 g g R G H nstitute for rocess ngineering Graz niversity of echnology ain heating systems in ustrian households in 4 olar, heat pumps.8% Gas 27.8% District heating 19.3% Wood heatings (most probably log wood boilers and stoves) 14.8% Wood lectricity 7.4% il 25.6% oal 1.9% og wood boilers (modern, installed since 1).5% Wood chips boilers 1.1% ellets boilers.8% otal number of households: 3.4 million (4) ources: tatistik ustria, 7 3 R G H nstitute for rocess ngineering Graz niversity of echnology iled stoves 41.6% ain and secondary heating systems based on solid biomass in ustria in 6 og wood boilers (modern, installed since 1) 2.9% on-woody biomass boilers.1% Wood chips boilers 4.1% Wood heatings (most probably log wood boilers and stoves)* 46.9% otal number: 1.8 million (6) ources: tatistik ustria, 7; Haneder et al., 7 ellets boilers 4.4% 4

3 g g R G H nstitute for rocess ngineering Graz niversity of echnology 5 nnual installations of central heating systems in ustria 1 ewly installed heating systems [1, units/a] otal new installations [1, units/a] ources: Regionalenergie teiermark, ear il boilers Gas boilers ellets boilers iomass boilers Heat pumps otal new installations 5 R G H nstitute for rocess ngineering Graz niversity of echnology iomass based residential heating technologies overview and classification Wood fuels iomass fuels on-wood fuels anually fed systems toves logwood briquettes oilers logwood briquettes utomatically fed systems iled stoves pellets toves pellets utomatically fed systems oilers straw pellets corn miscanthus iled stoves logwood briquettes oilers pellets wood chips 6

4 g g R G H nstitute for rocess ngineering Graz niversity of echnology anually fed (logwood, briquettes) and automatically fed (pellets) sually in batch operation and especially suitable for cold climates with slow temperature changes onstructed of pre-fabricated heavy stone plates or purely of stones according to defined guidelines During combustion the heat generated is stored in the stove and after the fire is extinguished, the heat is released to the surrounding during a considerable period of time (usually about 12 hrs) Flat bottom (no grate) o be de-ashed with shovels o air staging pacity range: usually 1 to 15 kw ource: ÖV, 7 iled stoves 7 R G H nstitute for rocess ngineering Graz niversity of echnology toves anually fed (logwood, briquettes) and automatically fed (pellets) imple design Firebox walls typically lined with chamotte or fire resistant material ometimes removable iron grates are inserted, and an ash box is placed below the grate Release of useful heat by radiation and/or convection to surroundings ombustion air is normally supplied as primary and secondary air and is controlled by usually manually and sometimes automatically driven valves pacity range: usually between 7 and 12 kw ource: Rika, 7 8

5 g g R G H anually fed nstitute for rocess ngineering Graz niversity of echnology ypes over-fire boilers downdraft boilers ver-fire boilers simple and cheap but normally high emissions of unburned hydrocarbons (especially at partial load operation) Downdraft boilers more stable combustion than in over-fire boilers air staging (primary and secondary combustion zone with separate air feed) pacity range: usually 15 to 7 kw suction fan ogwood boilers icroprocessor controller fuel storage secondary combustion (cyclone combustion chamber) Downdraft logwood boiler ource: Fröhling () 9 R G H nstitute for rocess ngineering Graz niversity of echnology Wood chip boilers roven automatic fuel feeding with burn-back protection Fully automatic operation (only ash box emptying needed) icro-processor controlled (load and combustion control) ypically vertical fire tube boilers with automatic or semi-automatic boiler cleaning pplication in domestic heating and micro grids as well as larger buildings (schools, hotels, etc.) ir staging (primary and secondary combustion zone with separate air feed) pacity range: usually 15 to 5 kw storage container 2 feeding screw 3 combustion chamber with radiation plate 4 heat exchanger with turbolators and cleaning system 5 ash container ource: W () 1 1 2

6 g g R G H nstitute for rocess ngineering Graz niversity of echnology utomatic fuel feeding (flexible or inflexible screw conveyors, pneumatic systems, agitators or combinations) with burn-back protection Fully automatic operation (only ash box emptying once or twice a year) icro-processor controlled (automated load and combustion control) ypically vertical fire tube boilers with automatic or semi-automatic boiler cleaning ellet boilers with flue gas condensation units already available ir staging (primary and secondary combustion zone with separate air feed) pacity range: 8 to 3 kw (usual capacities in ustria) ellet boilers 2 1. fuel container 2. stoker screw 3. primary combustion chamber 4... secondary air addition 5. secondary combustion chamber 6. heat exchanger with cleaning device 7. bottom ash container 8. fly ash container ource: Guntamatic () 11 1 R G H nstitute for rocess ngineering Graz niversity of echnology urrent state-of of-the-art measures for technology improve- ment and emission reduction During recent years permanent R&D have significantly improved the performance and user friendliness of small-scale combustion technologies mprovements were realised by the optimisation of: air staging burner design furnace design control systems reduction of auxiliary energy ncreasing activities to support new furnace designs by FD (computational fluid dynamics) simulations 12

7 g g R G H nstitute for rocess ngineering Graz niversity of echnology mprovement of small-scale scale combustion systems with respect to efficiencies (example) odern log wood boilers achieve efficiencies of more than 9% (compared to approximately 55% in the early 198 s) fficiency in % ource: Wörgetter et al., 5 year 13 R G H nstitute for rocess ngineering Graz niversity of echnology mprovement of small-scale scale combustion systems with respect to emissions (example) and total dust emissions - comparison between old and new pellet furnaces [mg/j] 15 1 Dust [mg/j] ources: Jungmeier et al., 1999; Wieselburg, 6, results from test stand measurements 14

8 g g R G H nstitute for rocess ngineering Graz niversity of echnology 1 emission sources in ustria (4) traffic 9,24 t/a industry 16,57 t/a agriculture 9,49 t/a ources: tatistik ustria, 7 small consumers 2,858 t/a power supply 1,28 t/a others 7 t/a small consumers residential heating natural gas 33 t/a fuel oil 215 t/a coal 595 t/a wood 6,369 t/a total 7,212 t/a otal 1 emissions: 46,7 t/a ontribution of residential heating: 15.4% ontribution of biomass based residential heating: 13.6% 15 R G H nstitute for rocess ngineering Graz niversity of echnology 1 emissions from residential heating systems in ustria wood boilers and stoves - old technologies 524 oil boilers and stoves 215 pellet boilers (status 6) 63 modern log wood boilers (installed 1-5) 66 modern wood chips boilers (installed 1-5) 77 gas boilers 33 1, 2, 3, 4, 5, 6, 1 emissions in [t/year] ource: chwarz, 7 16

9 g g R G H nstitute for rocess ngineering Graz niversity of echnology emission factors for old residential heating systems ctually applied emission factors for small-scale combustion units in ustria total dust combustion unit fuel emission factor dust [mg/j] stove 1) wood 148 stove 1) coal 153 stove 2) fuel oil extra light <.5 boiler 1) wood 9 boiler 1) coal 94 boiler 2) fuel oil extra light <.5 boiler 2) fuel oil light 2 xplanations: 1) related to small-scale combustion plants existing in ustria in 1997/98 2) related to small-scale combustion plants existing in ustria in ource: mweltbundesamt, 4 17 R G H nstitute for rocess ngineering Graz niversity of echnology echnological improvement of residential heating systems during the last 2 decades () otal dust emissions of wood chips boilers test stand measurements (type tests) between 1988 and total dust [mg/m³] xplanations: concentrations in mg/m³ related to dry flue gas and 13% 2 ources: [Wörgetter et al., 5] 18

10 g g R G H nstitute for rocess ngineering Graz niversity of echnology echnological improvement of residential heating systems during the last 2 decades () otal dust emissions of log wood boilers test stand measurements (type tests) between 1988 and total dust [mg/m³] year xplanations: concentrations in mg/m³ related to dry flue gas and 13% 2 ources: [Wörgetter et al., 5] 19 R G H 4 nstitute for rocess ngineering Graz niversity of echnology odern small-scale scale biomass boilers total dust and 1 emissions at full load operation 3 mg/j 1 td 1 td 1 td 1 td 1 td 1 td 1 td 1 W1 W2 W3 W4 W1 W2 xplanations: td total dust; e pellet furnace; W wood chip furnace; W log wood furnace; results from measurements performed with a total dust sampling equipment (dust) as well as a erner-type low-pressure impactor ( 1 ) ource: bernberger et al., 7

11 g g R G H nstitute for rocess ngineering Graz niversity of echnology -emissions from state-of of-the- art small-scale scale biomass combustion systems verage total dust emissions during stable full and partial load operation (related to dry flue gas and 13 vol% 2 ): log wood boilers: < 6.7 mg/j (1 mg/m³) pellet boilers: < 13.3 mg/j ( mg/m³) wood chip boilers: < 33.3 mg/j (6 mg/m³) tiled stoves: < 53.6 mg/j (83 mg/m³) sually, more than 9% of the total dust emissions are related to 1. onsidering all relevant operation modes including start-up, load changes and shut down the following 1 emission factors can be recommended for modern residential biomass heating systems log wood boilers: mg/j pellet boilers: mg/j (if softwood pellets are applied) wood chip boilers: -5 mg/j (depending on the -content of the fuel) 21 R G H nstitute for rocess ngineering Graz niversity of echnology onclusions and recommendations () n ustria 17.2% of the main heating systems (about 58. systems) are based on biomass combustion. n total (main and secondary heating systems) about 1.8 million smallscale biomass combustion appliances are installed. ogwood combustion in tiled stoves, stoves and boilers holds a share of approximately 88.5% of all biomass based heating systems. ld systems are thereby dominating. During the last decade about 15, to 22, new small-scale biomass heating plants have been installed per year. here is a broad variety of different modern boilers and stoves for logwood, pellets and wood chips combustion available in ustria. he technological performance of these systems has steadily strongly been improved during the last decades. 22

12 g g R G H nstitute for rocess ngineering Graz niversity of echnology onclusions and recommendations () Residential heating contributes with approximately 15.4% to the 1 emissions in ustria (status: 4). iomass combustion is the main 1 source of the residential heating sector (88% of the 1 emissions). his is mainly due to the high number of old systems in operation. While old biomass boilers and stoves show 1 emission factors of 9 mg/j respectively 148 mg/j, the emission factors for state-of-the-art automated systems are in the range of to 5 mg/j. herefore, it must be recommended to support the substitution of old biomass combustion systems by modern automated systems in order to considerably reduce 1 emissions from residential heating in a 2 - neutral and sustainable way. 23 R G H nstitute for rocess ngineering Graz niversity of echnology onclusions and recommendations () he further technological development of small-scale biomass boilers aims at zero emissions systems (<5 mg/j 1 ) to be achieved by appropriate primary and secondary measures. he combustion of agricultural biomass fuels in small-scale biomass combustion systems is not recommended due to considerably larger fine particulate emissions. 24

13 g g R G H nstitute for rocess ngineering Graz niversity of echnology cknowledgement R- ioenergy project iomass- lean biomass combustion in residential heating particulate measurements, sampling, and physicochemical and toxicological characterisation eine nitiative des undesministeriums für Verkehr, nnovation und echnologie (V) 25 R G H nstitute for rocess ngineering Graz niversity of echnology hank you for your attention rof. Dr. ngwald bernberger nffeldgasse 21b, -81 Graz, ustria.: +43 (316) 4813; FX: +43 (316) mail: obernberger@bios-bioenergy.at HG: 26