Development of a Screw Press Briquette Making Machine

Journal of Advanced & Applied Sciences (JAAS) Volume 03, Issue 01, Pages 1-10, 2015 Development of a Screw Press Briquette Making Machine Ojo, O. T. a,*, Mohammed, T.I. b a,* Department of Mechanical Engineering, Federal University of Technology, P.M.B 704, Akure, Ondo State, Nigeria. b Department of Mechanical Engineering, Federal University of Technology, P.M.B 704, Akure, Ondo State, Nigeria. * Corresponding author. Tel.:+2348062250605; E-mail address: wolex025@gmail.com A b s t r a c t Keywords: Briquette, Briquetting Machine, Design, Die, Fabrication, Screw Press. Accepted:18 December 2014 The design, fabrication and performance evaluation of a screw press briquette making machine has been carried out. The machine was designed in such a way that compression of biomass material in the briquetting die can be done with ease and the level of compression can be seen conveniently on the pressure gauge attached to the back of compression plate. The machine developed was fabricated using locally available raw material (mild steel), because of its strength, improved surface finish, rigidity, machinabilty, and availability. In evaluating the performance of the machine, it was used to produce briquettes from sawdust with cassava starch as binder. This performance evaluation results indicated that the machine is very effective when compared to other local briquetting machines that have been developed as this screw press briquetting machine can be used to produce briquettes of 200 mm in length, 46 mm in diameter and internal hole of 10 mm in diameter, from any biomass waste with production capacity of 1 briquette per minute and 60 briquette per hour. Academic Research Online Publisher. All rights reserved. 1. Introduction Briquetting is the process of converting loose biomass residues into high density of solid blocks that can be used as fuel for many heating purposes. It is a key strategy to make a clean, green and healthy environment [1]. Briquettes are alternative source of energy. They are solid fuels made from a variety of biomass wastes such as palm kernel shell, 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 can also be briquetted. These materials could be compacted to make briquettes using a mould. They could be made of different shapes and sizes depending on the mould. The appearance and burning characteristics of briquettes depend on the type of feed stock used. 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. Biomass briquetting is a technology which uses either a dry or a wet process to compress solid wastes into different shapes. It is the process of densification of biomass to produce homogeneous, uniformly sized solid pieces of high bulk density which can be conveniently used as a fuel. This is achieved by compacting solid composites of different sizes with

the application of little pressure, heat, as well as binding agent [2]. Today, many developing countries produce large quantities of agro residues but they are used ineffectively, thereby causing extensive pollution on the environment. Apart from the problem of pollution, other problems associated with these agro residues include that of transportation, storage and handling. Moreover, the direct burning of loose biomass in conventional grate is associated with very low thermal efficiency and wide spread of air pollution. In addition, a large percentage of unburnt carbonaceous ash has to be disposed off [3]. The importance of briquetting cannot be overemphasized. Briquetting is one of the alternative methods to save the consumption and dependency on fuel wood, densities of fuels can be easily handled, transported and stored. The process helps to solve residual disposal problems as well as the reduction of fuel wood deforestation; it provides additional income for farmers and creates job. In addition, briquettes have a consistent quality and high burning efficiency [4]. Briquetting technology is yet to get a strong foot hold in many developing countries because of technical constraints and lack of technology to suit local conditions. Overcoming the many operational problems associated with this technology and ensuring the quality of the raw material used are crucial factors in determining its commercial success. In addition to this commercial aspect, the importance of this technology lies in conserving wood, a commodity extensively used in the developing countries and leading to wide spread of deforestation [5]. The common types of biomass briquetting machines are; mechanical, hydraulic and screw presses [5]. Several researches had been conducted to prepare biomass briquettes, taken into consideration the design and construction of machine to produce these different types of briquettes. For instance, Grover et al. [5] made a comparison study between piston press and screw press briquette. They reported that the screw press briquette fuel has advantage over piston press such as; good combustion performance, long burning duration, uniform quality and suitability for gasifiers etc. The energy consumption for screw press briquette was only 60 kwh/ton. They also reported that Screw press briquette (SPB) are easy to burn and give better combustion than firewood. Since the density of these briquettes is higher than wood, the amount of air required is correspondingly greater for the same volume of briquettes. Yaman et al. [6] Produced the fuel briquette olive refuse and paper mill. Li et al. [7] employed the piston-mould process to produce densified log of wood residue. Chin et al. [3] used piston-mould process to densify sawdust, rice husks, peanut shell, coconut fibres and palm fruit fibres into biomass briquettes respectively. Odole et al. [8] Designed and fabricated a manually operated briquette making machine. Though it was used in producing briquettes, it has low compacting pressure as well as low production rate. He recommended the need to develop locally made briquetting machines that would be powered by hydraulic or electric motor which are capable of exerting more pressure and produce better and high quality briquettes. The aim of this paper is to design and fabricate a screw press briquetting machine which can be operated effectively and efficiently by a single operator, and at the same time is capable of producing high quality, high density briquettes which can be used for domestic and industrial heating purposes. 2. Materials and Methods In fabricating this screw press briquetting machine, mild steel was used in preference to other available materials because of the following factors; It is widely available, it can easily be machined, it has an improved surface finish, it has a low carbon content of 0.15% - 0.25%, it is suitable for fabrication of machine parts and can be joined together by welding with both oxy-acetylene and electric arc welding method. 2.1 Design Analysis of some of Machine Components The following components were designed for the machine in this study: The machine frame, flat table top, and hopper, shaft, bearing / bearing housing,

screw conveyor, die, compression plate, pressure gauge compartment, and briquette collection table. The isometric view of the machine design and the table of machine part are shown in figure 1. Fig. 1: Isometric View of the Machine Design The orthographic view of the machine is shown in Figure 2 below: The exploded view of the machine is shown in figure 3 below: Fig.2: Orthographic View of the Machine

2.2 Basic Design Formulae Used in the Design. Fig. 3: Exploded View of the Machine Design Analysis of the frame. A frame is a structure on which main units of a machine tool are assemble. The frame was designed to accommodate the electric motor, bearing, screw conveyor, briquetting die, hopper, and pressure indicator. It also has a detachable/ adjustable plate for easy collection of the briquettes coming from the die. Material used is mild steel. The area of the top of frame is calculated using equation 1 Area = L B (1) L is the length of frame B is the breadth of frame Design Analysis of the Hopper Fig. 4: Diagram of a square base truncated pyramid, a is the inlet length and width of hopper, b is the outlet length and width of hopper,h is the height of hopper,x is the height of the small cone below the frustum (hopper),h is the height of the pyramid. According to [9], the volume of the hopper was calculated using the equations 2, 3, and 4; V = V 1 V 2 (2) V 1 = 1 3 a2 H, (3) V 2 = 1 3 b2 x (4) V = volume of hopper,

V 1 = volume of pyramid, V 2 = volume of small cone below the frustum Determination of Speed of Shaft According to [10], the speed of shaft was determined using the equation below; N 1 = D 2 (5) N 2 D 1 N 1 is the speed of the motor (rev/min), N 2 is the speed of the shaft (rev/min), D 1 is the diameter of motor pulley (mm), D 2 is the diameter of shaft pulley (mm). According to [10], the tension in the tight side of the belt was determined from equation 6; T 1 = T T C (6) T 1 is the tension in the tight side of the belt (N) T is the maximum tension (N) T C is the centrifugal tension in Newton (N) Determination of the Tension in the Slack Side of the Belt According to [10], the tension in the slack side of the belt was calculated using the equation below; 2.3log [ T 1 T 2 ] = μ. θ. cosecβ (7) T 1 is the tension in the tight side of the belt, T 2 is the tension in the slack side of the belt in Newton, μ is the coefficient of friction between belt and pulley, θ is the angle of contact on the motor pulley, in radian (rad), β is the groove angle of the pulley in degree ( ). Determination of the Power Transmitted by the Belt According to [10], the power transmitted by V belt can be determined using the equation below; P = (T 1 T 2 )V (8) P is the power transmitted by V belt in Watts T 1 is the tension in the tight side of the belt in Newton (N) T 2 is the tension in the slack side of the belt in Newton (N) V is the belt velocity in metre per second (ms 1 ) Design Analysis of the Shaft A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and resultant torque set up within the shaft permits the power to be transferred to various machine members linked up to the shaft. Materials used for shaft should have the following properties which include; high strength, good machine-ability, low notch sensitivity and good heat treatment properties. Stresses induced in the shaft include; Shear stress due to the transmission of torque, i.e due to torsional load, bending stress (tensile or compressive) due to the forces acting upon machine element like pulley as well as the weight of the shaft itself, stress due to combined torsional and bending stress and stress due to axial loading [10]. Determination of Torque, T For belt drive, the torque was obtained from the equation given by [10]. T = (T 1 T 2 )R (9) T is the twisting moment or torque pulley in Newtonmillimeter T 1 is the tension in the tight side of the belt in Newton T 2 is the tension in the slack side of the belt in Newton R is the radius of the shaft pulley Determination of Power Developed by Shaft In determining the power developed by the rotating shaft, the equation below was used according to [10]: P = 2πNT (10) 60 Therefore, P = 2πN 2T 60 Where; P is the power developed by the rotating shaft, N 2 is the speed of the shaft (rev/min),

T is the twisting moment or Torque pulley. Determination of Machine Efficiency According to [10], the efficiency of the machine was calculated from the equation below; Machine Efficiency Determination of Maximum Bending Stress on the Shaft In determining the maximum bending stress on the shaft, the equation below was used according to [10]: σ b (max. ) σ b (max. ) is the maximum bending stress on the rotating shaft σ b is the bending stress induced due to bending moment τ is the shear stress induced due to twisting moment. Machine Fabrication Process Power Transmitted by Motor = 100 Power Developed by Shaft = 1 2 σ b + 1 2 (σ b) 2 + 4(τ) 2 (12) The various processes involved in the fabrication of this machine include; i. measurement ii. making out iii. cutting iv. welding v. drilling vi. grinding vii. painting Assembly and Welding of Machine Components Various parts of the machine that were welded together include the frame, hopper, flat table top, screw conveyor, screw conveyor casing, die, compression plate, bearing, extension table, spring and the pressure gauge. Electric arc welding was used in welding various parts of the machine using electrodes. The welding of parts began with the welding of angle iron to form the machine frame. This was followed by the welding of the flat table top upon which other machine members are mounted and welded together based on the design. These machine members include; the screw conveyor casing which accommodates the screw conveyor, the hopper which was welded to the hole made in the conveyor casing, the briquetting die which was welded to the screw conveyor, the compression plate and the pressure gauge. An extension (adjustable) table on which briquettes produced can be received was attached to the main frame through the use of bolts and nuts and it was raised to meet with the end of the briquetting die in such a way that the briquette coming out of the moves into the extension table easily to avoid the briquette being shattered. Angle iron of 15 mm long was used as side reinforcements for the screw conveyor casing and the die and were welded and bolted to the flat table top to ensure rigidity of the machine against vibration during operation. The electric motor was firmly fixed under the table using bolts and nuts and it is connected to the shaft pulley through a V belt. All parts of the machine were firmly secured to ensure rigidity and support. The finishing of the fabricated machine involves grinding the welded joints and painting with emulsion paint. Principle of Operation of the Machine The fabricated screw press briquette making machine operates in such a way that once the electric motor is plugged in to a three phase electricity source and it is switched on, the power transmitted by the motor drives and rotates the shaft (screw conveyor) of the machine through the V- Belt. As the power from the electric motor drives the shaft, it forces the screw conveyor to rotate and force the prepared biomass material which has been properly mixed with binder to move into the briquetting die. The compression plate which has a pressure gauge attached to it remains closed during this process in order to compress the material being forced into the die by the screw conveyor. With spring connection at the back of the compression plate which is welded in between the plate and the pressure gauge, the pressure level of the material being compressed in the briquetting die is read on the pressure indicator. At compression of 200

bar, the compression plate is opened and with the volume of quantity of prepared materials inside the hopper and the electric motor still at work, the compressed briquette is gently pushed out by the rotating screw conveyor into the extension table and the briquette produced is cut. The moment the compressed briquette comes out of the briquetting die, the compression plate is closed again and the production process continues. The machine is capable of producing briquettes of 46 mm in diameter and 200 mm in length with internal (centre) hole of 10mm in diameter. The essence of the internal hole is to support the combustion of briquettes. It is worthy of note that once the biomass materials are prepared and the machine is in continuous operation, the machine is capable of producing 1briquette per minute and 60 briquettes per hour under normal condition. Performance and Evaluation of the Machine In producing briquettes from the machine developed, a known quantity of sawdust was sourced for from a local sawmail. It was taken to Animal Production and Health Laboratory of Federal University of Technology Akure (FUTA), where it was pulverized in order to increase the surface area and to enhance binding efficiency. 1.2 kg of the pulverized sawdust was then mixed thoroughly with Cassava starch and 1.5 litres of water. Cassava Starch was used as the binder because; it is cheap, it is readily available and it burns lightly without smoke when used in small quantity. Briquettes were produced from the machine with the material that had been prepared using the procedures stated on the principle of operation of the fabricated machine. Briquettes produced were thereafter sundried. 3. Results and Discussion The fabricated screw press briquetting machine is shown in Figure 5. Fig. 5: The Fabricated Screw Press Machine The fabricated screw press briquette making machine was tested and was used to produce briquettes from saw dust. The compacting force of the rotating screw conveyor was able to gently force the mixture of the material inside the hopper into the die where compression took place. The pressure gauge worked effectively as the pressure deflection was read on the pressure gauge. The length of briquettes produced from the machine is 200 mm and a diameter of 46 mm and an internal centre hole of 10 mm in diameter. The machine developed is capable of briquetting any biomass waste. Preparation of sawdust took some time as the pulverized sawdust was properly mixed with little quantity of starch and water. For the first prepared raw material, 1.2 kg of sawdust was thoroughly mixed with 1.5 litres of water together with starch to form the mixture. When this prepared material was

poured into the hopper, it took about 4 minutes before the material could be fully compressed and ejected. This was due to the fact that water in the mixture was not enough to perform self-lubrication of the internal section of the briquetting die so as to facilitate the ease at which compression and ejection ought to take place. Another mixture of pulverized sawdust, starch and water was subsequently prepared. In this mixture, 1.2 kg of pulverized sawdust was thoroughly mixed with 2 liters of water. When this mixture was poured into the hopper, compression and ejection of briquette produced was done with ease within a minute. Hence, when using the machine to produce briquettes, the quantity of water in the mixture must not be too much in order to prevent breakage of briquette when it is been ejected from the die into the table. Also, water in the mixture must not be too small in order to prevent stock-pilling of the biomass waste inside the hopper and the die. Figure 6 (a) is the picture of the sawdust briquettes produced from the machine showing the length of the briquettes. Fig.6: (a) Sawdust briquettes produced from the fabricated machine, (b): Sawdust briquettes produced from the fabricated machine Figure 6 (b) is the picture of the sawdust briquettes produced from the machine showing the internal hole in the briquettes produced. 4. Conclusion The screw press briquette making machine has been developed. Performance evaluation of the machine had been done. The machine developed is a simple technology which will be an addition to technologies needed to help in solving problems of agro-waste management, deforestation, environmental pollution as well as creating a clean, green and healthy environment. The machine designed and fabricated is easy to maintain and the performance shows that the machine is very effective and efficient compared to other locally made briquetting machine. References [1] David F. and Anne W.: Biomass Briquetting, A Publication of Food and Agriculture Organization (FAO) of the United Nations, Bangkok 1996. [2] Pham K. Applications of Briquetting Technology to Produce Briquettes from Agricultural Residues and By- Products; 1995: Available from http:// www.restsasia.ait.ac (Accessed on 25/04/14). [3] Chin O.C and Saddiqui K. M. Characteristics of some Biomass Briquettes Prepared under Modest die Pressure. Biomass and Bioenergy Journal; 2000; 18: 223-228 [4] Jeng S.L, Zainuddin A. M, Sharifah R. W, and Haslends A. A Review on Utilization of Biomass from Rice Industry as a Source of Renewable Energy, Journal of Renewable and Sustainable Energy Reviews. Published by Elsevier Ltd. 2012; 16: 3084-3094.

[5] Grover P.G and Mishra S.K. Biomass Briquetting Technology and Practices. A Publication of Food and Agriculture Organization of the United Nations, Bangkok. 1996. [6] Yaman S., Sahan M. and Haykiri A. Production of Fuel Briquettes from Olive Refuse and Paper Mill Wastes, Journal of Fuel Processing Technology. 2000; 68: 23-31 [7] Li Y., Liu H. and Zhang O. High Pressure Densification of Wood Residues to Form an Upgraded Fuel, Journal of Fuel Processing Technology. 2001; 19: 177-186. [8] Odole O.A. Design and Fabrication of a Manually Operated Briquette Making Machine, A Thesis of Mechanical Engineering Department, Federal University of Technology Akure. 2006. [9] Macrae M.F., Kalejaiye A.O., Chima Z.I., Garba G.U., Ademosu M.O., Channon J.B., Mcleish A.S. and Head H.C. New General Mathematics for Senior Secondary Schools Book 1. Pearson Education Limited. 2011; 190-191. [10] Khurmi R.S. and Gupta J.K. A Textbook on Machine Design, Fourteenth Edition; Eurasia Publishing House (PVT.) Ltd. 2005