PELLETime INVESTIGATES ALTERNATIVE RAW MATERIALS OF PELLET PRODUCTION. Yliopistonkatu 6, FIN JOENSUU FINLAND

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1 PELLETime INVESTIGATES ALTERNATIVE RAW MATERIALS OF PELLET PRODUCTION Lasse Okkonen 1, Simo Paukkunen 1, Heikki Lamberg 2, Olli Sippula 2, Jarkko Tissari 2, Jorma Jokiniemi 2 1 North Karelia University of Applied Sciences Yliopistonkatu 6, FIN JOENSUU FINLAND Tel lasse.okkonen@pkamk.fi 2 University of Kuopio, Department of Environmental Science, Fine Particle and Aerosol Technology Laboratory P.O.Box 1627, FIN KUOPIO FINLAND ABSTRACT: This paper presents the first round of pelletizing trials and fuel analysis in Finland, being part of a Northern Periphery Programme (NPP) project, PELLETime Solutions for competitive pellet production in medium size enterprises. The applied research process and the results of pelletizing of forest chips of spruce logging residues and whole-tree pine are presented. Trials were carried out by North Karelia University of Applied Sciences (NKUAS) and Lokapelletti Ltd. in Central Finland in September The combustion and emission analysis of the produced pellets were carried out by University of Kuopio (FINE Fine Particle and Aerosol Technology Laboratory). The tests were carried out in a laboratory using a modern 25 kw pellet boiler. Fine particle emissions and gaseous emissions for carbon monoxide (CO), nitrous oxides (NO X ) and organic gaseous compounds (OGC) were measured. Finally pellets were end-used in local household boilers, and experiences listed to inform further research. 1 PELLETime PROJECT The overall objective of PELLETime is to facilitate establishment of SMEs in small scale pellet production, support existing pellet production, and, enhance energy availability throughout the NPP region. As a result it will make a significant contribution to efficient use of natural resources, and to climate change mitigation and renewable energy policy objectives. To this end the project will need to resolve key issues concerning shortages of raw materials, technical difficulties in handling and processing different raw material streams and widespread lack of information and understanding amongst both producers and consumers. The project will identify current and future potential availability of both existing raw materials and alternative raw materials. GIS analysis will identify any bottlenecks arising from fluctuations in existing raw material supply over time and regional markets will also be analysed to highlight areas where these bottlenecks could become a significant constraint on market development. In these areas development of new raw materials will be vital and the project will examine the potential of a range of agricultural and short rotation forestry crops, developing best practice guidance on the landscape, biodiversity and hydrological dimensions of management. Handling, logistics and innovative techniques for matching variable raw materials to different end user requirements will be modelled and a cost-calculator will be developed to allow SMEs to assess the feasibility of local pellet production. Potential new raw materials and mixtures of raw materials will be pelletized and tested in terms of fuel quality, calorific value and emissions and the results will form the basis for a best practice guidance document on utilisation of different raw materials and mixtures in small and medium scale pellet production. PELLETime is coordinated by the North Karelia University of Applied Sciences, Finland.

2 Partnership includes Finnish Forest Research Institute, Joensuu Regional Development Centre (Finland), University of Kuopio (Finland), Oulu University of Applied Sciences (Finland), Highland Birchwoods (Scotland), Swedish University of Agricultural Sciences, Herads- and Austurslandskogar (Iceland) and Icelandic Forest Service. Project also includes associate partners of Vapo Corporation Ltd. (Finland), Biottori Ltd. (Finland), Pakaslahti Ltd. (Finland), HT Enerco Ltd. (JPK-Tuote) (Finland), Veljekset Hassinen Ltd. (Finland) and National Farmers Union Scotland, among others. Figure 1: Main target regions of PELLETime (Northern Periphery Programme). 2 PELLETIZING TRIALS 2.1 Trials setting The pelletizing trials were part of the work on broadening the raw material base of pellets and investigating the opportunities to decrease dependency on conventional by-products streams. The raw materials investigated in autumn 2008 were woodchips of spruce logging residues from final fellings and woodchips of whole tree pine from early thinnings. Both raw materials were submitted green with needles, branches and bark, and were approximately in 45% moisture content. Raw materials were harvested from North Karelia by Metsäpalvelu Turunen Ltd. Drying of the woodchips was carried out at the Bioenergy Development Centre of The Jyväskylä University of Applied Sciences, located in Saarijärvi, Central Finland. Dryer s energy was solar and biomass based district heat, and approximately 660 kwh/ton of woodchips was needed to dry the chips from 45% to %. Pelletizing was carried out at the Lokapelletti Ltd. in Laitila, using small-scale pellet press (horizontal fixed ring die with maximum capacity of appr.240 kg/h) developed by the Konepaja M. Pappinen Ltd. Firstly chips were milled by a hammer mill to smaller particle size (10 mm sieve), and then pelletized. Die had press channel length of 40 mm. 2.2 Quality properties of pellets produced The quality of the pellets produced was not the best possible but pellets were seemingly soft. This is partly due to big particle size of milled material and relatively short press channel applied. However, the objective of trials was to produce pellets for emission and combustion analysis, not to optimize the physical qualities.

3 Table 1. The results of pelletizing trial. Whole-tree pine Spruce logging residues Die temperature ( C) Moisture of raw material (%) Moisture of pellet (%) Pellet weight (g) Pellet length (mm) Pellet diameter (mm) Hardness kg (Kahl-hardness) Bulk density of raw material (kg/m 3 ) Bulk density of pellet (kg/m 3 ) COMBUSTION TESTS Combustion tests of the pellets were made by Fine Particle and Aerosol Technology Laboratory in a University of Kuopio. Laboratory has facilities for testing pellets made of different raw materials as well as testing of different small-scale combustion appliances. The pellet boiler used in these tests was a Biotech PZ-RL with a maximum output of 25 kw. The pellet boiler represents a modern design with primary and secondary air control and lambda sensor. Fine particle emissions were done from diluted flue gas. Experimental setup was similar to previous study done in the laboratory [1]. Fine particle emission measurements included the determinations of particle number-size distribution, mass-size distribution and fine particle mass emission (PM1). Fine particle chemical compositions were analyzed from the PM1 filter samples, including ash species and different carbon fractions. The number-size distributions, and number concentrations as well as gaseous compounds in the flue gas were measured with on-line instruments. Hood Filtration TI Flue gas fan CO 2 Dilution tunnel TI Partial flow ELPI Cooling PM1- impactors PM1.0-filters DLPI FMPS FTIR TI Pellet boiler OGC CO NO O CO 2 2 NO 2 TI = Temperature indication --- = Thermal insulation Figure 2. The experimental setup of the combustion tests. Testing system was placed in a laboratory with fixed dilution system. Flue gases from the pellet boiler went through a stack. After the stack, flue gases were transferred outside through a hood by a flue gas fan. There was a space between the stack and the hood, so that the flue gas fan in a hood does not affect the draught in a combustion appliance. Part of the flue gas was transported to the dilution tunnel where the particle measurements were done. Gaseous measurements were done from an undiluted flue gas.

4 3.1 Particle and gaseous emissions Fine particle emissions for spruce pellet and pine pellet were 28 mg/mj and 17 mg/mj, respectively. Previously, 12 mg/mj fine particle emission was measured in the same boiler with commercial wood pellet [2]. The particles mainly consisted of inorganic material, volatilized from the fuel during combustion and the amounts of incomplete combustion products (soot, organics) were small. With both of the fuels that were tested, most abundant elements in the particle mass were potassium, chloride and sulphate. Smaller amounts of calcium, zinc, sodium, iron, organic material, elemental carbon and carbonate were found. 30 Fine particle mass emissions [mg/mj] Other not analyzed Other analyzed EC, elemental carbon CO3, Carbonate OM, organic material SO4 Cl Fe Zn Na K 0 Spruce logging residues Whole tree pine from first thinnings Commercial pellet Ca Figure 3. Fine particle mass emissions with pellets made from spruce logging residues and pellets made from whole tree pine from first thinning pellet. Figure also represents the most abundant chemical components in the particles. In small-scale combustion particle emissions are usually formed in two ways: from incomplete combustion (elemental carbon and organic material) and from ash forming elements, which are inorganic material that vaporize in combustion process and later form particles when the flue gas cools down. The amount of ash in particles is strongly related to the amount of ash forming elements in the fuel. Gaseous emissions were measured for carbon monoxide (CO), nitrous oxides (NO X ) and organic gaseous compounds (OGC). Gaseous emissions for spruce pellet were CO 240 mg/mj, NO X 170 mg/mj and OGC 3.4 mgc/mj. Gaseous emissions for pine pellet were CO 320 mg/mj, NO X 110 mg/mj and OGC 4.7 mgc/mj.

5 CO and NOx emissions [mg/mj] OGC emissions [mgc/mj] Carbon monixide, CO Nitrogen oxides, NOx Organic gaseous compounds, OGC Spruce logging residues Whole tree pine from first thinnings Commercial pellet 0 Figure 4. The gaseous emissions with spruce and pine pellet. Carbon monoxide emissions (CO) and nitrogen oxides emissions (NO X ) are represented in mg/mj. Organic gaseous carbon (OGC) represents the total amount of gaseous hydrocarbons in the flue gas [mgc/mj]. 3.2 User experiences The produced pellets were end-used by households in Eno, North Karelia. This was organised to gather opinions and experiences. There were two households with Velmax 20 kw and one with Tatano 70 kw boiler. The amount used was small (only some hundreds kg per user), but in this short experiment no problems emerged when well-informed person had made proper adjustments. However, any generalisations can not be drawn. The ash content of pellets produced of spruce logging residues was 2.3 m-% (Avg), and pellets produced of pine from early thinning 0.7 m-% (Avg.), analyzed as ignition residue at 550 o C. The ash melting temperatures for spruce pellet were 1170 C (DT/A) and 1290 C (FT/D), and for pine pellets 1400 C (DT/A) and >1450 C (FT/D). 4 DISCUSSION Pelletizing trial aimed to produce pellets for combustion and emission analysis. Therefore the physical quality was not optimal. This however, can be improved e.g. by milling to smaller particle size and increasing the length of the press channel. Fine particle emissions from the pine pellets were on a similar level with the commercial pellet while the emissions from spruce were clearly higher. This difference was evidently caused by the higher amount of ash forming elements (especially potassium) in the spruce pellets. Generally, pellets that contain bark have higher amount of ash forming elements. CO and OGC emissions from the modern small-scale pellet boilers are relatively low, when the boiler operates optimally, which was also seen in the current tests. However, differences between the tested fuels were observed. Both CO and OGC emissions were higher with the studied pellets than with commercial wood pellets. Furthermore, the NO X emissions were also higher from the studied fuels when compared to the commercial pellets which can be explained by different fuel nitrogen contents. The end-use of pellets in small amount was carried out in households. Well-informed user could avoid technical problems, but still no generalisation or any recommendations can be given. The pellets produces of these alternative raw materials are suitable for larger-scale, but authors do consider that the whole-tree pine has potential to become raw material for higher quality pellets. In forthcoming trials, material will be tested also with a bark-removing technology.

6 5 REFERENCES [1] Tissari, J., Lyyränen, J., Hytönen, K., Sippula, O., Tapper, U., Frey, A., Saarnio, K., Pennanen, A.S., Hillamo, R., Salonen, R.O., Hirvonen, M.-R. and Jokiniemi, J Fine particle and gaseous emissions from normal and smouldering combustion in a conventional masonry heater. Atmospheric Environment 42, [2] Lamberg, H., Sippula, O., Tissari, J. and Jokiniemi, J Effect of operating conditions on emissions from a modern pellet boiler. European Aerosol Conference 2008, Thessaloniki, Abstract T12A017P.