New Van Krevelen diagram and its correlation with the heating value of biomass

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1 Research Journal of Agriculture and Environmental Management. Vol. 2(), pp. 2951, October, 13 Available online at ISSN Apex Journal Full Length Research Paper New Van Krevelen diagram and its correlation with the heating value of biomass Marliati Ahmad 1, * and Handoko Subawi 2 1 Riau Islamic University, Pekanbaru Indonesia. 2 Indonesia Aerospace, Jl. Pajajaran, No. 154 Bandung Indonesia. Accepted 17 July, 13 This study was aimed to propose new Van Krevelen diagram on biomass by involving proximate and ultimate analysis data. The biomass groups were stratified into (a) coals and fuel, (b) organic waste and chemicals, and (c) wood and biofiber. The basic diagram correlates a hydrogen to oxygen content, all compared to carbon content in biomass with refers to ultimate analysis. The profiles of basic elements in biomass were also examined and to explore its corelation with heating value parameter by accomodating ash content on biomass. This study did not discuss moisture removal from biomass. Key words: Biomass, bioenergy, carbon content, ash content, heating value, fuel. INTRODUCTION A biomass is defined as part of agricultural product including waste and the rest of biodegradable animals, plants, forestry and municipal wastes. Biomass is renewable feedstock of bioenergy mainly waste of human activities and nature containing carbon. Nowadays, biomass feedstock covers 14% of global energy and contributes up to 38% of energy supply in developing countries (Beena and Bharat, 12). Utilization of agriculture and horticulture wastes provides large opportunities of huge renewable bioenergy in Indonesia. The utilization of oil palm waste through biogas processing offers electrical power generation up to 380 MW, excluding direct utilization as bioenergy feedstock for fuel, or its opportunity for animals feedstock (Alexis and Pierre, 1819). Potential bioenergy from biomass is intended to contribute to the increasing global energy consumption that is still dominated by fossil fuels (Handoko and Marliati, 12). The heating value potential of substances has being studied by researchers since long time ago. Initial study by Pierre Louis Dulong and Alexis Thérèse Petit examined heating content of substances in the form of heating capacity parameter. They proposed hypothesis *Corresponding author. marliatiahmad@yahoo.com about heating capacity of substances and predicted that volumetric heating capacity of all materials has the same value of 3 for solid materials (Handoko, 13). Law of DulongPetit (1819) currently does not prevail anymore due to more detail measurement that shows the broad range of values. This study focused on relationship between elements and the heating value of biomass. In parallel, the heating value data can be predicted by accomodating the elements and ash content of variety of biomass by means of proximate and ultimate analyses. MATERIAL AND METHODS This study employed two groups of data: i) Data of proximate analysis per ASTM D3175 providing fixed carbon content, volatile matter and ash content; ii) Data of ultimate analysis providing element content of carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulphur (S). The ash content was analysed per ASTM D1290 to describe elements included in ash of biomass. Correlation of the element content with heating value of biomass Determination of heating value of biomass can be

2 296 Res. J. Agric. Environ. Manage. obtained through measurement (HHV measured ) or by means of calculation (HHV calculated ) by accomodating parameters of carbon, hydrogen, oxygen, nitrogen, sulphur and ash content. High heating value (HHV) is obtained from completely oxidation of biomass sample yielding carbon dioxide gas and water liquid. The high heating value (HHV) is different with low heating value (LHV) that correlate with the heat released while hydrogen burned and turns to gas phase, and can be calculated based on HHV value and hydrogen fraction. The prediction method was used to determine HHV calculated as a comparison to the measured HHV measured in the laboratory. RESULTS The analysis data of biomass consist of proximate, ultimate analysis and heating value. The main constraint in empowering biomass feedstock either for heat sources or electricity, is burning efficiency level that has not been sufficiently competitive with the wood solid fuel. The constraint is indicated by parameter of ash content. Most of ash content is silica. High content of silica, kalium and also chlor in biomass will overlap to cause a clogging and slagging in a heating equipment with temperature over the melting point of ash. Biomass will be competitive and compatible with advanced technology if the high ash removal has been overcomed. Table 1 covers test result of ash, fixed carbon content and elements analysis in biomass (Jigisha et al., 05; Woodgas, 07 and Kirubakaran et al., 09)The carbon content, volatile matter and ash content in percentage values based on dry basis. It means excluding moisture content of each biomass. DISCUSSION In parallel experiment, it was found that the removal of high ash content in biomass can be performed through immersion in diluted alkaline solution at low temperature. An effort to remove ash content is strategically to maintain the heating facility. An experience in electrical power generation in Denmark (1997) found that straw biomass contained kalium over limit value of 0.2% and chlor more than 0.1%. Figure 1 shows relationship between ash content and heating value of biomass. The figure indicates that the lower ash content correlates with an increase of heating value of biomass. Biomass with lower ash content shows variety of heating value parameter. Heating value of biomass varies from MJ/kg until MJ/kg. The ash content in biomass are mostly less than % dry basis. The lower the ash content, the higher effectivity of oxidation process. Out of the variety of biomass, rice hull, rice husk, and rice straw have high ash content of about 23.5%,.6% and 19.8% respectively. Not all ash contains high silica. However, the rice straw, rice husk and rice hull show predominantly high silica content in its ash, beside kalium and chlor. The removal of ash content is very important in the empowerment of natural fiber such as feedstock in industry, or solid fuel. Oxidation elements contribute in burning process performance. The important elements in this case consist of carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulphur (S). Van Krevelen (19) tried to stratify soild fuel of biomass in simple diagram to correlate between parameter of H/C to parameter of O/C (Figure 2.). On the diagram, comparism between natural fuel and fossil fuel such as coals was illustrated. The diagram shows clearly the comparison between oxygen to hydrogen, based on carbon content. The lower heating value seems due to carbonto oxygen and carbontohydrogen bonds compared with carbontocarbon bond (Van Krevelen, 19; Peter, 02). This diagram differentiates groups of (a) biomass, (b) peat, lignite, (c) coal, and (d) anthracite. Anthracite contains lowest oxygen and hydrogen elements than other solid fuels. This study evaluated variety of biomass and fuels as a comparison on a diagram called new Van Krevelen diagram shown at Figure 3. The diagram has clear boundary line than Van Krevelen diagram. All data were grouped into (a) wood, (b) biofiber, (c) fuel, (d) coal, (e) organic chemicals and (f) organic waste. The new diagram identified wood as part of biofiber, and coal as part of fuel, whereas in the narrower range of oxygen and hydrogen there is organic waste as a part of organic chemical group. Groups of wood and biofiber contain varied oxygen, as O/C, between 0.75 and 1., in the range of certain hydrogen content. On the other hand, fuel groups including coals, char and tar have oxygen content, as O/C, from 0 until 0., with certain range of hydrogen. The relationship of HHV can be traced from carbon content as shown at Figure 4a. It followed a trend; the higher the carbon content, the higher heating value HHV. However this trend is more clear when sum of carbon and hydrogen content was compared Figure 4c.. Further, Figure 4b shows that higher oxygen content tends to decrease heating value. However, comparison between sum of oxygen and ash content made it clearer as shown at Figure 4d. The correlation of biomass elements content to the heating value, HHV, was formulated by Channiwala (1992) by involving fraction of carbon, hydrogen, oxygen, ash, sulphur and nitrogen that were obtained from ultimate analysis (Channiwala, 1992). Higher carbon content in biomass can be reached in char such as 89 to 92% in charcoal or 83 to 87% in coconut shell char. This is higher than 84 to 85% in anthracite.

3 Ahmad and Subawi 297 Tabel 1. Biomass component analysis and thermal measurement. No Feedstock Volatile matter % Ash % Fixed Carbon % C H O N S Measured HHV (MJ/kg) 1 Acetone Acetic acid Dglucose Phenol Cellulose Lignin (softwood) Lignin(hardwood) Coal Pittsburgh seam Peat SH Charcoal Oak char (565C) Casuarina char (9C) Coconut shell char (7C) Eucalyptus char (9 o C) Northumberland no.8anth Coal Coal sample L Charcoal Redwood char790 o F Oak char81185 o F Coconut shell char7 o C QrC PhC EsC Bagasse Coconut coir Corn stalks Rice straw Wheat straw Wheat straw Cotton stalk Sugarcane baggase Water hyacinth Brown kelp, soquel point Wheat straw Paddy straw Cotton stalk Mulberry stick Coconut coir Sena leaves Sugarcane leaves Dallake weed Tea bush Salseed husk Eucalyptus sawdust

4 298 Res. J. Agric. Environ. Manage. Table 1. Contd. 47 Noctane Benzene Motor gasoline Kerosene Methanol Ethanol LBL wood oil BOM wood oil Coke oven tar Low temp tar Carbonmonoxide Acetylene Carbon Carbondioxide Coconut shell Coir pith Corn cob Groundnut shell Millet husk Rice husk Peach pits Walnut shells Corn cobs Rice hulls Pine needles PeachPit Macadamia shell Pistachio shell Cottonshells Spiremint Corncob Corncob Cottongin waste Douglass fir bark Loblolly pinebark Eucalyptus camaldulensis Sudan grass Almond prunings Black walnut prunings Corn stover Cottongin trash Eucatlyptus bark Almond Cabernet Sauvignon Teawaste Cottongin waste Cottongin trash Alabama Oakwood waste Subabul wood Black locust

5 Ahmad and Subawi 299 Table 1. Contd. 97 Douglas fir Ponderosa pine Red alder Redwood WesternHemcock White fir White oak Madrone Mango wood Casuarina Poplar Plywood Pressmud briquettes Plywood Wood Chips Canyonlive Oak Redwood Softwood Spruce wood Pinewood Subabul wood Eucalyptus EucalyptusGrandis Subabul Douglas Fir White Fir Tan Oak Beech Hickory Maple Poplar Yellow pine Source: Jigisha Parikha (05), Woodgas (07), and Kirubakaran et al. (09). Ash content (%) Figure 1. Ash content in biomass. Figure 2. Old Van Krevelen diagram of biomass. Source: Van (19), McKendry (02).

6 0 Res. J. Agric. Environ. Manage. Figure 3. New Van Krevelen diagram of biomass C (%) O (%) (4a) (4b) H + C (%) O + A (%) (4c) (4d) Figure 4. Diagram of HHV to biomass component.

7 Ahmad and Subawi 1 The fixed carbon in rice straw reaches 12 to %. Sugarcane baggase has fixed carbon about 15%. Most of biomass contains fixed carbon from until %. During long period, carbon content may reach to the value of 0% such as anthracite, or by heat treatment such as char formation or through chemical processing to remove ash content in rice straw, etc through chemical immersion in diluted alkaline solution (Jan et al., 06). REFERENCES Beena P., Bharat, G. (12). Biomass characterization and its use as solid fuel for combustion. Iranica J. Energy Environ., 3(2), ISSN , DOI: Alexis T.P., Pierre L.D. (1819). Recherches sur quelques points importants de la théorie de la chaleur. Annales de Chimie et de Physique,, Handoko, S., Marliati, A. (12). Oil Palm: Palm Oil, Biocomposite, Bioenergy. LAP Lambert, Saarbrucken, Germany. ISBN Handoko S. (13). Hydrocarbon: Energy Security, Fuel, Petrochemicals, Carbon Fiber. LAP Lambert, Saarbrucken, Germany. ISBN Jigisha, P., Channiwalab, S.A., Ghosal, G.K. (05). A correlation for calculating HHV from proximate analysis of solid fuels. Elsevier. Fuel, 84, Woodgas, (07). Proximate and ultimate analyses. Biomass Energy Foundation. Kirubakaran, V., Sivaramakrishnan, V., Nalini, R., Sekar T., Premalathae, M., Subramaniane, P. (09). A review on gasification of biomass. Elsevier. Renewable Sustain. Energy Rev., 13, Van Krevelen, D.W., (19). Graphicalstatistical method for the study of structure and reaction processes of coal. Fuel, 29, Peter M. (02). Energy production from biomass, overview of biomass. Applied Environmental Research Centre, Bioresour. Technol., 83, Channiwala, (1992). The Indian Insitute of Technology, Bombay. On S.Gaur and T.Reed, (1998). Thermal data for natural and synthetic fuels. Marcel Dekker. Jan P., Alexandra P., Fleming III, P.D. (06). Two step straw processing as a new concept of silica problem solution. Department of Chemical Engineering, and Imaging. Western Michigan University, Kalamazoo.