Biomass Briquettes production.

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THE POTENTIAL OF SAWDUST ENHANCED WITH CASSAVA PEEL, CORN COB AS RAW MATERIALS FOR BRIQUETTE PRODUCTION

ABSTARCT
The study investigated the potential of sawdust enhanced with cassava peel, corn cob as a raw materials for briquette production, cassava flour(starch) was used as binder for production of fuel briquettes. It also evaluated some physical and combustion characteristics. The materials were manually collected,sorted, sun-dried, and the cassava peel, and corn cob were milled to particle sizes distribution ranging from <0.25 to 3.80mm using hammer mill. The three materials were combined at mixing percentages of 90:10, 70:30 and 50:50 Briquettes were produced using a hydraulic piston press. Compacting pressure was varied from 10 to 20MPa at an interval of 5 MPa. The results indicated that the relaxed density of briquettes produced from particles of only ranged from 541 to 659 kg/m3 whilst that made from a mixture of sawdust, cassava peel and corn con ranged from 685 to 865 kg/m3. Additionally, at all compacting pressure levels, briquettes made from sawdust only had an impact resistance index of 0.5%. Whilst those made from a combination of saw dust, cassava and Corn cob ranged from 115% to 500%. Thus, briquettes with adequate physical and mechanical characteristics could be produced from sawdust at room temperature using low compacting pressure when sawdust are combined with cassava peel, and corn cob. These findings could enhance the existing technology for densifying agricultural residues, for example, sawdust, especially in rural communities. Fuel availability has implications on the nation’s economy. Felling trees for fuel wood which is the practice in many rural communities disrupts the ecosystem. Briquettes made from agricultural residues could replace fuel wood and mitigate the problems of deforestation. The physical properties including; compression ratio, tumbling resistance, resistance to water penetration, shatter resistance, maximum density, relaxed density, density ratio, relaxation ratio, and percentage volume reduction of each briquette sample were also determined. ASTM standard methods were also used to determine the proximate analysis including; moisture content, ash content, volatile matter, burning rate, and fixed carbon content of each briquette samples. The mean maximum density of sawdust briquette, corn cob and cassava peel briquette and admixture of sawdust, corn cob and cassava peels were 780.38kg/m3, 730.38kg/m3 and 641.20kg/m3 respectively. The mean relaxed density of sawdust briquette, cassava peel briquette , corn cob and admixture of sawdust and cassava peels were 568.40kg/m3, 504.84kg/m3 and 454.18kg/m3 respectively. The mean density ratio of sawdust briquette, cassava peel briquette and admixture of sawdust and cassava peels were 0.77, 0.81, and 0.85 respectively. The mean relaxation ratio of sawdust briquette, cassava peel briquette and admixture of sawdust, cassava peel and corn cob were 1.32, 1.67 and 1.62 respectively. The mean compression ratio of sawdust briquette, cassava peel briquette and admixture of sawdust and cassava peels were 4.2, 3.0 and 2.55 respectively. The moisture content, ash content and volatile matter determined for sawdust briquette, cassava peel briquette, corn cob and admixture of sawdust and cassava peels were (5.24, 10.07, 17.11)%; (11.75, 4.40, 3.24)%; and (64.01, 63.50, 55.14)% respectively while the corresponding values of fixed carbon content in order listed above are 14.86, 5.60 and 10.42%. The results shows that briquettes prepared from sawdust enhanced with cassava peel, and corn cob had high resistance to shattering, high resistance to water penetration, low moisture content, and low ash content followed by sawdust, cassava peel and corn cob.
The briquettes can serves for local use, making available alternative source of energy. Also the cost of the briquettes can be afforded by rural dwellers when produced in mass. Its mass production can also make job opportunities available and this can limit deforestation.

Background of the Study
As the population of the world continues to grow, the demand for energy is becoming critical challenge for the world’s energy leaders (Christoph Frei, 2012). Eradicating poverty and hunger and providing energy are crucial for sustainable development goals. Briquettes are alternative source of energy. They are solid fuels made from a variety of biomass wastes such as palm kernel shell, corn cob, coconut shell, rice husk, rice bran, charcoal from low density wood, agro-forestry waste material and municipal waste. Large quantity of wood residue such as saw dust, cassava peel can also be briquetted. These materiNals could be compacted to make briquettes using a mould. They could be made of different shapes and sizes depending on the mould. Briquettes are mostly used in the developing world, where cooking fuels are not as easily available. This work is based on the potential of sawdust enhanced with cassava peel, corn cob as a raw materials for the production of briquettes . Briquetting is a way to make use of biomass residues such as sawdust, straw or rice husk, into high density solid blocks that would otherwise go to waste, and replace the use of wood and charcoal (often produced unsustainably) and fossil fuels, thus cutting greenhouse gas emissions.
Briquettes are easier to store and use for cooking than wood, because they are uniform in size and composition. They are much cleaner to handle than charcoal or coal, and produce less local air pollution. Briquettes have high specific density (1200-1450 kg/m3) compared to 60 to 180 (kg/m3) of loose agro-residues. Briquettes are widely used for any thermal applications. These include steam generation in boilers, domestic heating purpose, used as flammable material in brick kilns, paper mills, chemical units, dyeing houses, food processing units and oil mills and many others.
Without access to modern energy services, the poor in the developing countries are deprived of many potentials. So Nigeria being one of the developing countries is currently in need of high energy in order to hold its fast growth. Due to the easy availability of wood in Nigeria, wood charcoal has been the main source fuel for cooking. But wood charcoal is risky to use due to its bad consequence on health and its disadvantage of pollution. The quality of life has been improved by using energy resource for different daily activities of human beings; however, it has also created many problems. Global warming and harmful effects on the environment are the most serious ones affecting human health and causing pollution. Also it is now coming to be clear that the nonrenewable resources are gradually coming to an end; oil, natural gas, and coal are going to be depleted. Thus, energy problem is becoming very serious and the main objective is to assess a solution to fill the gap between demand and supply of energy sources .Therefore, energy should be conserved and used wisely and alternative energy should be assessed.

MATERIALS AND METHODS
Production and testing of briquettes Processes
Collection of materials (sorting out the materials to be used in the briquetting)
This involves the collection of materials to be compacted, then the sorting of the materials when all unwanted materials are removed. The materials can also be sieved. For materials like corn cobs, corn straws, groundnut and other materials large in size, chopping is required to reduce them to small sizes.

Preparing of materials
The collected materials that have been sorted are then prepared further to be briquetted. Here, mixing of different materials is done if required an example is a combination of paper waste and corn stalks. Also, for briquetting that involves the use of binders, in preparation of the materials, an appropriate binder fit for the material is added and mixed with the materials to be briquetted, this is to ensure the compactness of the briquette that would be formed.

Addition of Water
Water is usually added to the feedstock to make them loose and easy to work on. Some biomass materials require to be soaked in water for a number of days to ensure that they are soft enough to work on (Musa,2007).
Plate 1: Sawdust mix with cassava peel, corn cob, water and starch
Compacting
After the above processes, the material is now ready to compacted using the briquetting technology available. The materials are fed into the mould and are operated on. After application of enough pressure, the briquettes compacted are ready to be removed.
Removing, drying or cooling and storing.
After compaction, the briquettes made are removed carefully and sun dried for as long as it’s required. After proper drying, briquettes can then be cooled and stored

Production of Briquettes
Collection of Materials
The materials used were selected based on its availability in the locality as proximity to source of raw is very important as this would aid easy and more production of briquettes. The materials used include:

1. Cassava peels
2. Sawdust
3. Corn cob
4. Starch
5. Water
   Sawdust was collected from a saw mill industry at Camp, Abeokuta in large quantity as required and it was used as collected, and no much further sorting was required. Cassava peels on the other hand was collected from a garri making factory along Alabata road. Cassava peels were sun dried to remove the moisture content for 5 days, after which, the peels were crushed into smaller particles. Corn cob was collected from centre for community based-farming (COBFAS) at conanim farm in Funaab, the corb con was sun dried to removed the moisture for 6 days, after which, the corn cob were crushed into smaller particles. The binder used was starch which was bought from Kuto market in Abeokuta in quantity required for the work to be carried out. The starch is combustible binder.
   Preparation of Materials
   The starch to be used as binder was cooked. The quantity of starch required was firstly mixed with a small quantity of cold water which was poured into a boiling water and the mixture was stirred gradually and continuously until a viscous liquid mixture was achieved. The mixture was then left to cool at room temperature.
   To start with, bowls to be used were labeled A, B, C, and D Then, 0.25kg of sawdust was poured into the bowl labeled A. Same quantity of cassava peels was also weighed and poured into bowls labeled B. Same quantity of corn cob was weighed and poured into bowl labeled C. In the bowl labeled C, a mixture of 0.125kg of sawdust, 0.125kg of cassava peels and 0.125kg of corncob was measured. The cooked starch was then poured in required amount weighed in each of the bowls containing the raw materials and mixed thoroughly till they could be formed into a shape by the hands. The proportion of mixture of each samples is shown in table 3. The properly mixed samples are then ready to be briquetted.
   Compaction of Materials
   The fabricated briquette making machine was used in compaction of the materials. The prepared materials were fed into the moulds of the machine. The machine was operated to compress the materials in the moulds. After about 35 minutes, the briquetted samples were then ejected from the moulds.
   Removing and Drying
   The briquetted samples after being removed, were placed a platform to dry. The samples were sun dried. The briquettes produced are shown in plate 4, as they are placed to be dried.

Plate 2: 50% Saw dust + 50% Cassava Peels +50% Cassava peel.

Table 3: Composition of briquette samples
Briquette samples SD:CP:CC ratio SD (kg) CP(kg) CC kg S (kg) W(kg)

1. 1:0:0 0.25 0 0 0.15 0.18
2. 0:1:0 0 0.25 0 0.15 0.18
4. 1:1:1 0.0.1 0.125 0 0.125 0 0.125 0.25
   0.26. 0.15 0.29. 0.18

SD- Saw Dust CP- Cassava Peels CC-Corn Cob S- Starch W-Water

Determination of Physico-Chemical Properties of Briquettes
Determination of the Mass of briquettes
Masses of the briquettes produced were determined by using a method of direct measurement. A weighing scale was directly used to determine the masses of the briquettes. Each briquettes was placed on the weighing to determine its mass immediately after ejection from the moulds. The masses were measured in kilograms.
Determination of the Volume of briquettes
The volume of each briquette sample was determined using a method of indirect measurement. This was done by taking the dimensions of the briquette sample, the height (H), the base or top length (L) and base or top width (B) with the breadth. LxBXH=Volume.