Seminar Reed for Bio-energy and Construction. Reed as bio-energy: opportunities to use it in boiler-houses and as biogas source

Transcription

1 Seminar Reed for Bio-energy and Construction Reed as bio-energy: opportunities to use it in boiler-houses and as biogas source Ülo Kask Tallinn University of Technology , College of Landbased Studies, Piikiö, Finland

2 Content Reed resources and location Reed as bio-fuel characteristics Reed based bio-fuels Suitable burning equipment Conclusions

3 Reed resources and location in Estonia

4 County Reed beds area, ha (2000) Estonian reed resources by counties Corrected reed beds area, ha (2007) ** Harvestable area, ha/y Energy content, MWh/y Yield, t/ha Theoretical Realistic Harju , Hiiu , Saare , Pärnu , Viljandi , Valga ,5 *** Võru ,5 *** Lääne-Viru , Tartu , Põlva , Lääne , Ida-Viru * ,5 *** Järva * ,5 *** Jõgeva * ,5 *** Rapla * ,5 *** Total

5 Remarks to previous table * In the Ida-Viru, Järva, Jõgeva, and Rapla counties the reed bed areas have been omitted before ** Values in column 3 were corrected in 2007, based on orthographic photos and partially on satellite images in the Saare, Lääne, Pärnu and Hiiu County. *** The average yield in Estonia according to the winter measurements of 2006 and In other counties the real average data of yield measurements (TUT TED) have been used. Column 4 shows the estimated possibly and sustainably harvestable area of reed beds (approximately half of corrected area). According to the winter measurements in 2006, at the moisture content of 20% the average energy content of reed is 3.94 MWh/t (TUT TED). As to produce pellets from all harvested reed, total amount of primary energy can rise to 373 GWh/y (energy content 4.5 MWh/t). Approximately single family houses could be heated during the year.

6 Reed as bio-fuel characteristics The most significant combustion parameters are: moisture content, calorific value, content of volatiles, ash content and composition. These have been determined in the TUT TED.

7 Combustion characteristic of reed Elemental composition of dry reed fuel, % Element Ranges Average Winter Summer Winter Summer Carbon, C 46,96 48,34 46,13 47,11 47,5 46,5 Hydrogen, H 5,50 5,60 5,93 6,42 5,6 6,2 Oxygen, O 42,75 43,84 39,7 42,2 43,3 40,7 Nitrogen, N 0,23 0,34 0,57 1,17 0,3 1,0 Sulphur, S 0,03 0,09 0,12 0,45 0,04 0,2 Chlorine, Cl 0,05 0,18 0,28 0,48 0,1 0,4

8 Combustion characteristic The reed combustion characteristics vary to some extent depending both on the site of growth (on the shore of sea or lake, river deltas, wetland treatment systems) and seasonally (harvested either in summer or winter). Fuel source Combustible matter, % C p H p S p N p O p Lake reed ,02-0,2 0,24-1, Seashore reed ,01-0,3 0,23-1, Peat ,4-0, Wood ,05 0,

9 Moisture content dynamics of reed from October till May in

10 Combustion characteristic Heating value of dry matter of reed fuel Parameters: Calorific value, MJ/kg Energy content, MWh/t Ranges Average Winter Summer Winter Summer Q p /q b, 18,62 19,16 18,33 18,77 18,92 18,51 Q ük /q gr, d 18,62 19,16 18,31 18,75 18,91 18,49 Q ak /q net, d 17,48 18,01 17,02 17,44 17,77 17,21 Q a 20 /q net, 20 * 13,68 14,86 13,16 13,49 14,17 13,31 E 20 / E 20, MWh/t* 3,80 4,13 3,65 3,75 3,94 3,70 *at moisture content 20 %

11 Combustion characteristic The yield and characteristics slightly depend on harvesting period and site of growth of reed. Main characteristics Seashore reed Lake reed Winter Summer Winter Summer Moisture, % 23,7 60,4 21,1 60,5 Yield of dry matter, t/ha 6,9 8,7 8,1 7,4 Volatile matter, % 82,0 75,7 82,3 77,1 Ash content of dry matter (at 550 ºC), % 3,5 6,3 3,1 5,7 Net calorific value of dry matter, MJ/kg (Q ak /q net, d) 17,5

12 Combustion characteristic Ash The ash as a solid residue formed by combustion plays an important role in the selection and running of combustion equipment and its auxiliary devices. The ash content of reed harvested in winter is %, in average 3.2 %, but for summer harvested reed it is significantly higher being %, in average 5.8 %.

13 Combustion characteristic Chemical composition of reed ash at (550 o C), %. Ranges Average Component Winter Summer Winter Summer SiO 2 65,34 85,50 25,90 48,33 77,77 37,10 Fe 2 O 3 0,13 0,84 0,17 1,69 0,29 0,70 Al 2 O 3 0,1 1,69 0,11 1,12 0,57 0,61 CaO 3,07 7,27 4,02 11,53 4,42 6,84 MgO 0,4 1,45 1,87 4,88 1,22 3,33 Na 2 O 1,96 9,05 0,87 10,98 3,19 3,61 K 2 O 0,99 5,69 14,89 31,33 4,26 24,77 Other 1,57 19,4 17,28 33,5 8,28 23,04

14 Reed ash The chemical composition of reed ash for summer and winter harvest differs essentially for the content of SiO 2 and K 2 O. The reed harvested in winter would be a much better fuel to burn in the combustion equipment from the point of view of ash composition. The ash of reed harvested and dried in summer contains in significant amounts alkali metals that influence both ash fusibility, fouling - formation of ash deposits on the heating surfaces - and corrosion.

15 Content of some elements in winter reed ash, mg/kg. (ENAS Oy) Pilliroo tuhaanalüüs, ENAS OY Sisaldus mg/kg, kuivaines Rocca al Mare Peipsi järv Saaremaa Ca Mg Na K Mn Cd Cr Cu Pb Ni Zn S Fe Al P

16 Fusibility characteristics of reed (summer and winter reed 2006) Fusibility characteristics of summer reed Samples from different places I I I I I I I Point of deformation (IT) O C, Softening temperature (ST) O C Formation of hemisphere (HT) O C Flow temperature (FT) O C Fusibility characteristics of winter reed Point of deformation (IT) O C, Softening temperature (ST) O C Formation of hemisphere (HT) O C Flow temperature (FT) O C up to 1340 don't melt up to 1330 don't melt up to 1330 dont' melt up to 1350 don't melt up to don't melt 1290

17 Reed ash It is important to note that the summer reed ash cone fused down at the temperature lower than C, initial deformation took place at temperatures below 800 C (see at the Table, slide 16). On the other hand ash of the winter reed has not fused down even at C; only one sample shows evidence the deformation temperature only ~ 800 C. We are able to state that average ash-fusibility temperatures for summer and winter reed ashes differ 200 K. This proves that the reed as a boiler fuel must be most definitely harvested in winter, when the nutrients and minerals have accumulated in the roots (rhizome) and leaves have fallen.

18 Samples of ash of reed fuels (left: pellets; right: stalks

19 Burning tests of reed briquettes in home oven

20 Ash fusibility of reed and wood mixture Flow temperature (FT), C y = -2E-05x 3 + 0,0875x 2-11,239x ,5 R 2 = 0, Share of wood ash in mixture, %

21 The flow temperature of the mixture of reed and wood ash has minimum point at certain rate what is approximately 100 K less from corresponding wood ash flow temperature. Minimum occurs at the share of wood ash % in mixture and it is different for separate fusibility characteristics. For point of deformation the minimum is at the share of wood ash 45 %, for flowing temperature 65%.

22 Recommended maximum proportions of Reed Canary Grass together with wood or peat when a fuel-mix is used in a fluidized bed boiler. (Source: Vapo Ltd, Novox Ltd.).

23 Laboratory tests of reed-to-biogas productivity from summer reed Biogas(-methane) potential measurements, 12 samples from all coastal area reed beds of Estonia Rocca al Mare Mahu Kiideva Peipsi

24 Chemical analysis Sample Dry N, % P, % K, % Ca, % Mg, % Cellulose, Lignine, Hemicellulose, matter, % % % % 1.Silma 44,31 0,690 0,087 0,568 0,155 0,036 40,16 6,93 30,63 2.Rocca al Mare 28,40 2,183 0,201 2,029 0,253 0,067 35,50 7,21 27,31 3.Puhtu 41,58 1,103 0,097 0,956 0,176 0,085 39,12 8,38 28,37 4.Jõesuu 38,86 0,889 0,078 0,802 0,230 0,063 34,11 7,15 28,48 5.Puhtu (old) 81,78 0,326 0,028 0,084 0,077 0,023 45,65 12,37 28,48 6.Vaibla 27,03 2,089 0,199 1,733 0,298 0,094 33,44 5,03 28,42 7.Kiideva 41,34 0,872 0,113 0,917 0,104 0,065 39,91 7,94 31,33 8.Haapsalu-Aiavilja 39,46 1,166 0,155 0,953 0,213 0,121 32,93 5,96 31,19 9.Lüübnitsa 32,62 1,842 0,179 1,033 0,256 0,058 35,74 8,01 31,62 10.Turbuneeme 33,89 1,377 0,138 1,170 0,229 0,125 35,10 8,02 31,20 11.Haapsalu-Papiniidu 42,64 1,092 0,146 0,774 0,267 0,106 36,70 9,74 30,31 12.Popovitsa 34,43 1,348 0,146 0,917 0,223 0,084 36,30 7,89 31,11

25 Results

26 Methane production, mmol Sample Marked as Colour TV Inok TV Inok Lüübnitsa PR 1 Popovitsa PR 2 Puhtu PR 3 Kiideva PR 4.2 Aiavilja PR 5 Papiniidu PR 6 Turbuneeme PR 7 Rocca al Mare PR 8.2 Silma PR 9.2 Vaibla PR 10 Jõesuu PR 11.2 Rocca al Mare (2) PR 12

27 Composition of biogas

28 Biomethane potential measurements from reed samples: conclusions (1) Biogas of good quality, without impurities (H 2 S, NH 3 ) but moderate CH 4 concentration (49 55%); Quick start up of fermentation process (5 7 days); Stable fermentation, no accumulation of metabolites (VFAs etc); Methane potential is in the range of m 3 /kg per organic material.

29 Biomethane potential measurements from reed samples: conclusions (2) Comparison with previous studies from The biogas potential is higher from reed grown on soil with abundant concentration of nutrients (ie more polluted); The biogas potential is higher from reed harvested late in summer as compared to reed harvested in early summer or in autumn; Biogas potential is higher from the 2 step digestion as compared to the single step one. Inoculum should be added at least in a week, after the acid formation stage; Biomethane potential was in the range of m 3 /kg organic material. 29

30 Biogas yield of green reed Parameter Only leaves, Peipsi All plant, Mahu All plant, Peipsi All plant, Rocca al Mare Biogas per dry matter, l/g or m 3 /kg 0,428 0,487 0,450 0,533 Biogas per volatiles, l/g or m 3 /kg 0,391 0,437 0,417 0,500 Biogas per matter as received, l/g or m 3 /kg 0,238 0,149 0,166 0,162

31 Solid reed fuel

32 Combustion equipment The variety of equipment burning herbaceous biomass is rather wide and finding the suitable one depends much on which kind of fuel the user wants to burn, either: pressed (pellets, briquettes), packed (baled), crushed (shreded).

33 Combustion equipment The stocker burner EcoTec The Stocker burner IWABO Villa S 20 Three hours after the ignition of reed pellets the burning process slowed down due to the burner clogging (the same had happened earlier when the combustion of straw pellets was tested).

34 Pellet burner of KWB EasyFlex (Austria) The firing system is designed as an underfeed firing system with afterburning ring. Due to the special arrangement of secondary air jets in the afterburning ring, perfect turbulence, high combustion temperatures and thus cleaner burnout of the combustion gases are guaranteed. Optionally has the KWB EasyFlex burner extension, in which the burner plate is equipped with an efficient cleaning mechanism. This makes the burner even more reliable when using slagging and ash-rich standard pellets.

35 Pellet boiler, KWB

36 Combustion equipment Simple boiler for burning paled straw, where the air controls performed by temperature of flue gases

37 Combustion equipment Scheme of the facility for burning crushed (scarified) straw

38 Combustion equipment Cigar-type burner for straw bales

39 Combustion equipment Fluidized bed combustion Circulated FBC, Bubble bed combustion

40 Conclusions Based on the laboratory tests and pilot tests in boiler-houses the use of fuel reed (shred reed and pellets) has proved to be suitable partially. In order to gain further experience, tests should be carried out to find suitable fuel handling technologies and combustion equipment and develop combustion regimes for different types of reed. It must be considered that these fuels can be added to other biomass-based fuels, however the peculiarities of their cocombustion should be studied. One suitable way to handle reed as fuel is to make silage and digest it anaerobically for biogas. Biogas as a engine fuel for CHP and transport vehicles.

41 Thank you for your attention! Here we are coming!