Ecological briquettes from sunflower seed husk

Transcription

1 Eologial briquettes from sunflower seed husk Cosmin Spirhez 1, Aurel Lunguleasa 1, and Cătălin Croitoru 1 Transilvania University of Brasov, Wood Proessing and Design Wooden Produt Department, 9 Street Eroilor, Brasov, Romania Transilvania University of Brasov, Engineering Materials Department, 9 Street Eroilor, Brasov, Romania Abstrat. The paper aims to use the waste of sun-flower hulls in order to obtain some lignoellulosi briquettes as renewable solid fuels. First, the sunflower seed husks were ground, after that they were sorted and only the frations orresponding to the briquettes and pellets were used. After obtaining the stable briquettes there were determined the physial and alori properties of briquettes manufatured from sunflower husks, as potential alternative biofuels. The moisture ontent, ash ontent and density of the briquettes have been determined and orrelated with their alorifi properties, namely the alorifi value and alorifi density. The experimental results have indiated that, even if the self-adhesion of sunflower seed hulls is less than that of wood sawdust, they have a better behaviour in humid environment. Good results make it possible to use these briquettes for both household heating systems and thermal power plants. 1 Introdution Nowadays there is an impinging potential risis of fossil fuels, as researh shows a shortage for oil and oal in the next years [1,]. Wood that traditionally was used as energy soure sine anient times is urrently under regulation, as most of ountries from the European Union are onerned with the preserving of the natural forest biotopes []. Due to these regulations imposed at national level, even inferior quality wood (obtained from branhes and boughs), beomes less available [3,4]. Biomass is a renewable energeti soure, beause it inreases from one year to another, it is widely spread world-wide and presents low osts in omparison to the fossil fuels, the biomass resoures, from whih fuel material is produed may inlude wood and wooden wastes, agriultural ereals and wastes resulted from their prodution, aquati biomass and algae [1,15]. Wood industry by-produts, suh as sawdust, have been suessfully used for the manufaturing of briquettes with satisfatory alori properties, but nowadays a great deal of attention are foused on other type of biomass-derived materials, suh as fruit seeds, peels and so forth [3-8]. By appropriately modifying the properties of these biomass-derived materials, for example by thermal treatment, they ould be transformed in superior fuels suh as briquettes and pellets. Oleaginous seed husks have attrated attention lately due to their generation as byprodut in onsiderable amounts in the oil prodution industry [9] and to their potential use as high alori-output materials, aided by the trae amounts of fatty polyesters. A sun-flower seeds proessing unit has a urrent apaity of 400 tons in 4 hours, from whih it results approximately 100 tons of seed shelling. Although the sun-flower seed shelling are wastes of the main prodution proess (Fig 1), it is neessary to manage them, beause they an lead to blokages in the storage faility of the fatories. The main uses of sunflower seed shelling are in the briquettes and pellets field, and in the lignoellulose omposites. They are reported to ombust with minimal emissions of volatile organi ompounds in the atmosphere, thus making them useful as an alternative eologi fuel. Fig. 1. Sunflower oil prodution flow Materials and methods For determining the effetive density of the briquettes, 1 piees of pellets have been hosen and mahined to The Authors, published by EDP Sienes. This is an open aess artile distributed under the terms of the Creative Commons Attribution Liense 4.0 (

2 obtain regular ylindrial speimens, usually by sanding ends with dis mahine. The effetive density is usually determined as a ratio between mass and volume. The relation in Eq.1 (onsidering the ylindrial form of briquettes) had been used in order to obtain effetive density of briquettes: 4m l ef d 3 ( g / m ) (1) Where: m is mass of briquettes, in g; d- diameter of briquettes, in mm; l- length of briquettes, in mm. From these briquettes, some samples with smaller lengths were extrated in order to be used for ompressive strength. To determine the breakout endurane of the materials, a universal mehanial testing instrument was used, where there were installed two ompression plates, as see in Fig. Fig.. Determining the ompression strength of briquettes F d l [ N / mm ] σ is the ompressive strength, in N/mm ; F- Maximum fore of briquettes rash, in N; d- Diameter of briquettes, in mm; σ is the ompressive strength, in N/mm ; F- Maximum fore of briquettes rash, in N; d- Diameter of briquettes, in mm; l- length of briquettes samples, in mm. The installation used for determining the alorifi value of the wooden biomass was the explosive burning (bomb) alorimeter type XRY-1C, produed by Shanghai Changji Geologial Instrument Co., from China (Fig. 3). Before testing the alibration of the alorimetri bomb was performed with benzoi aid with a known value of alorifi value (6 463 kj/kg). With this value of alorifi value, the alorimetri oeffiient noted with k of alorimeter will be obtained, using the normal proedure of determination and equation of CV determination (Eq.3). k ( t t ) n f i CV qi [ kj / kg] (3) m i1 CV is alorifi value, in kj/kg; k- alorifi oeffiient of alorimeter, in kj/celsius; t f final temperature, in Celsius; t i-initial temperature, in Celsius; m-mass of sample, in kg; n q i i1 is supplementary heat release in time of testing, in kj/kg. Supplementary heat is given by burning nikelhromium and otton wires and also by burning of HNO 3 (usually 40 J). The ompressive strength of briquettes is determined as a ratio between fore and area of analyzed surfae (Eq.). F N mm A ( / ) () σ is the ompressive strength, in N/mm ; F- Maximum fore of briquettes rash, in N; A area of ompressive rash surfae, in mm. Fig show that all stresses are onentrated in the middle zone of briquettes, namely the broken surfae is given by diameter and length of these samples, that form a speifially area of breakage. Taking in onsideration the above aspets, the ompressive strength will be determined with the next relation: Fig. 3. Setion view through alorimetri bomb The inferior alori power of the sunflower husk pellets is determined based on the superior alori power, expressed in Eq.4:

3 LCV= HCV 6 (MC + 9h) [kj/kg] (4) LCV- inferior alori power, kj/kg MC- wood moisture ontent of sample, kj/kg h- hydrogen ontent of the sample, estimated at 3.6%, for the lignoellulosi materials. The testing sample (1) is tied to the otton thread () and is put in the alorimeter hamber (3). The opper nikel thread (4) is tied to the sample and the otton thread, after whih the protetion overs (5) is attahed. The alorimeter hamber is onneted to the alorimetri bomb over 6 through two eletrodes (7) and (8), whih ontinue with the eletrial threads for alorimetri bombs oupling (9) and (10). By threading the over, the bomb (11) is oupled to fitting (1) to the oxygen supplying unit, generating a total pressure of 30 atmospheres. In fig. 4 the desription of the proess to determine the alorifi power is presented, as there were presented by the omputer software. The preparation of the test faility requires a series of outdoor ativities, but also the introdution of data on the omputer interfae (suh as sample weight, alorifi value, et.) The test proedure has three main and different steps [11, 18]: The first stage ("fore") has as purpose the determination of temperature variations of water in the alorimetri reipient, due to the heat exhange with the exterior before burning. During this period, usually for 5 minutes, the temperature is determined at speified intervals with the preision thermoouple. The last reading of the temperature from the first period represents in fat the first temperature in the main period. The values of the temperature registered in this period are six. After registering the 6 th value the flaming/ignition of the material takes plae and its reading on the menu bar ( burning time ). periods. The values registered during this period vary aording to the burning time of the fuel material in the alorimetri bomb. The number of registered temperature values may vary between 19 4 during this period. These periods are usually equaled wit time of this period in minutes. The final period ("after") has as purpose the determination of the average water temperature in the alorimetri reipient, due to the heat exhange with the exterior vessel after burning. Idential to the first stage, the temperature is shown at half minute periods, for 4-5 mutes and on average there are registered 8 10 values of the temperature variation. The last temperature value is the final temperature value and is reorded by the omputer software. After that, the omputer software displays the end of the test by word and position end " by software. For the superior alorifi power, the value obtained was of 1956 kj/kg, while for the inferior alorifi power, the average value obtained was kj/kg. To determine the ash ontent of the seed husks, the general method of standardized determination was used (ASTM D866-11, 01). Aording to this method, the milled and dried material (dried to 0% moisture ontent) is alined at a temperature of 750 C in a laboratory alibrated oven, for a period of at least 3 hours (Fig. 5). The pellets alination is made on a metalli melting ruible resistant to elevated temperature of 750 Celsius degrees, and the weighting was made on an analytial balane with a 3-deimal preision. When determining the ash ontent, it will be taken into onsideration that the sample is ompletely dried and the leaned and empty melting pot weight, as in Eq.5 [1, 13]. ma m A 100 [%] (5) m m s m a+ -mass of ash, onsidering the ruible, in g; m s+- mas of sample onsidering the ruible, in g; m - mass of empty ruible, in g. Fig. 4. Desription of the proess to determine the alorifi power The main period ("main") begins by burning (flaming) the sample and has as onsequene the inrease of water temperature in the alorimetri reipient, due to the burning of the pellet and heat delivery to ontainer. The values of the temperature are indiated at one-minute Fig. 5. Oven for determining the ash ontent 3 Results and disution The average mean of the sunflower briquettes density is (g/m 3 ) (Fig.6). Large variations ould be due to the differenes in ompatness. 3

4 Fig. 6. The density of the briquettes Fig.7 depits the observed breakout endurane of briquettes, for the twelve samples taken into analysis. The average breakout resistane or rash strength for the briquettes is MPa. Fig. 7. Compressive strength of briquettes In fig. 8 presented the variation of ash ontent, ative arbon and volatile substanes. Fig. 8. Ash ontent, ative arbon and volatile substanes in the briquettes The amount of ash ontained is about.4%, the amount of ative arbon is.7%, and the amount of volatile is 7% as determined in other researh [14]. 4 Conlusions The sun-flower seeds shelling are a waste from sunflower oil fatory. These huge wastes may be used suessfully in briquettes, after their grinding, sorting and drying without using other additives. From this point of view these obtained briquettes are some natural fuel materials that an be used suessfully for obtaining heat in stoves or furnaes. The results presented in the paper have indiated that the obtained briquettes ould in priniple suessfully replae the wooden sawdust briquettes or even the fire wood, due to the good density and the very good alori power. The ash ontent of.4% is like some of European wooden speies. The burning of briquettes obtained from sun-flower husk produe a lean energy, used for stoves or furnaes. This kind of briquettes has not signifiantly influene the general properties of briquettes but it makes a major ontribution to their ombustion properties beause of low moisture ontent. This is one of the main reasons (apart from eonomi arguments) why many briquette produers are going to do next step namely to hange raw materials from wood to agriultural waste. The rushing strength values obtained in the paper should over the real rushing strengths, even for the most restritive standards. Proedure of determination of breaking strength is very simple and eluidates the ompatness and onsisteny of briquettes, thus improving the quality and properties of these produts. Consequently this study has pratial importane for produers and ustomers of briquettes. Biomass is one of the forms of renewable soures whih may be onverted in solid, liquid and gaseous energeti fuel and whih may generate energy as heat by its burning, as well as eletrial energy by onversion proesses. Presently the biomass ontributes with approximately 1% to the prodution of primary energy in the world, and in the ountries in developing proess it overs 40-50% of the neessary of energy. The Biomass is the alternative soure that, aording to ontributed with 7% from the energy produed in the world. Presently, the use of renewable fuel materials suh as wooden wastes for produing biofuels inreases the hanes of biomass in the availability level on the energeti market. Biomass is environmentally friendly and a neutral energy against the emissions of arbon dioxide. The arbon dioxide is absorbed by the plants during the growing proess and forms a losed iruit, beause the quantity of arbon dioxide whih was absorbed by the plants during the growing proess will be equal to the one whih was eliminated during the omplete burning proess. Aknowledgement We wish to aknowledge stuff of Transilvania University of Brasov, Projet nr. 8063/ (The program of quality evaluation of briquettes from sunflower seed husk). Referenes 1. T. Banta, R. De Leona, Parametri study of rie husk torrefation for the development of sustainable 4

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