Investigations into Physical and Fuel Characteristics of Briquettes Produced from Cassava and Yam Peels

Globally, 140 billion metric tons of biomass is generated every year from agriculture. This volume of biomass can be converted to an enormous amount of energy and raw materials. These residues are usually dumped and flared on the farms, where they constitute health risk to both human and ecology. Densification of these residues would improve their bulk handling, transportation and storage properties. Therefore, this work investigated densification characteristics of cassava and yam peels using an experimental briquetting machine. The ASAE standard methods were used to determine the moisture contents (dry basis) and densities of the milled residues and briquettes, while ASTM standard methods were used to determine the proximate and ultimate analyses of the residues. The initial, maximum and relaxed densities were also determined using ASAE standard methods. Also evaluated were compaction, density and relaxation ratios of the briquettes. The mechanical properties were determined using universal testing machine, while the heating value was determined using Ballistic Bomb calorimeter. The mean moisture contents of cassava and yam peels residues were 10.19% and 9.27% respectively, while those of relaxed briquettes were 8.76% and 7.95% respectively.  The initial, maximum and relaxed densities were 251.50 kg/m3; 741.13 kg/m3 and 386.4 kg/m3 respectively for briquettes produced from cassava peel, while the corresponding values for briquettes produced from yam peel were 283.40 kg/m3; 911.45 kg/m3 and 512.54 kg/m3 respectively. The compaction ratio of 2.94 and 3.21 were obtained for briquettes produced from cassava and yam peels respectively. The compressive strength of briquette from cassava peel was 1.53kN/m2 (SD 0.05), while that of yam peel was 1.76kN/m2 (SD 0.04). The higher heating value of briquettes from cassava peel was found to be 12,765kJ/kg (SD 30), while the corresponding value for yam peel was 17,348kJ/kg (SD 20). The results of this work indicate that briquettes produced from the two biomass residues would make good biomass fuels. However, findings show that yam peel briquette has more positive attributes of biomass fuel than its cassava peel counterpart. It has a moderate moisture content of 10.95 %, higher density of 911.45 kg/m3 and lower relaxation ratio of 1.78. Other positive attributes of yam peel briquette over cassava peel are long after glow time of 375 secs and slow propagation rate of 0.16 cm/s. It also has higher heating value of 17,348 kJ/kg and compressive strength of 1.76 kN/m2 compared to cassava peel, which are 12,765 kJ/kg and 1.53 kN/m2 respectively. Keywords: agricultural wastes, briquette, briquetting machine, cassava peel, yam peel

Development of a Pilot-scale Pulse Electric Field system for Processing Liquid Foods

Pulse-Electric Field (PEF) System can be described as a system that utilises high voltages applied at a specific interval and with a particular wave shape in treatment (inactivation and destruction of micro-organism cells) of liquid or solid food. Pulse-Electric Field food processing system reduces the drawbacks (such as deterioration in sensory values, energy contents, and freshness) of other methods significantly. To generate the high voltage needed for the treatment, a series of capacitors and diodes connected were used. Generation of the desired pulse shape, which is the square wave is achieved through ATmega-328 microcontroller. The pulse control system is made up of a button to vary the treatment time, the power switch and a 16x2 alphanumeric Liquid Crystal Display (LCD) which serves as visual feedback. For the evaluation of the fabricated system, bacteria were cultured using MacConkey agar solution and then diluted in orange juice which serves as samples of liquid food. From the samples prepared, the bacteria count is in order of 1.61x105CFU/mL before treatment, after treatment the count reduced to 1.01 x105CFU/mL and 2.10 x104CFU/mL concerning 1kHz and 2kHz pulse frequency used for the two samples treated

Mathematical Analysis and Thermal Modelling ofa Pilot-Scale Pyrolysis Gas Furnace

Anumerical model for the thermal operations directly related to all significant heat and mass transfer within a designed furnace chamber was developed, taking into consideration the surface area of the internal structures and surrounding furnace walls of the furnace. Some specific sets of theories on the internal and external flow of heat energy in furnaces as well as boilers were adopted and modified to exhibit a steady-state condition model for the designed gas-fired pyrolytic furnace. Existing thermal models were selected and adjusted to arrive at a unique mathematical model that was used to analyse and verify the heat distribution at different regions of the built pyrolytic furnace with the aid of the basic principles of heat and mass transfer and the associated assumptions. The distinctive numerical model formed the basis for the MATLAB Simulink program used to validate the experimental data gotten from runs of heating and cooling of the pyrolytic furnace during operation. The result of the simulated behaviour of the furnaceachieved afit to the estimation of the data of87.16%in correlation with the real experimental data. This established a thermal function that can be used asa model for potential optimisation of the pyrolysis process of the pilot furnace

Effect of Reactor Temperature on Pyrolysis of Lignocellulosic Medical Waste in a Fixed Bed Reactor

The lethargic modes of medical waste disposal in many developing countries have been a cause of concern to many regulatory agencies. In this study, effect of reactor temperature on pyrolysis of lignocellulosic medical waste in a fixed bed reactor was investigated. Gauze bandage was procured from AKOL Pharmacy, Ogbomoso, South-Western Nigeria. Samples of the gauze bandage, 40 g each at a time, were fed into a retort and the retort inserted into a developed fixed bed reactor for pyrolysis at different temperatures (300, 400, 500 and 600 oC) with a residence time of 15 minutes. Tar, gas and char yields were weighed using an electronic balance (WT20002T, RS232C) and were further expressed in percentage of the initial weight of the sample. Results showed that tar and gas yields increased with increasing reactor temperature while char yield decreased with it. Both intraand extra-particle secondary reactions were insignificant and therefore could not influence the yield spectra of products. The highest yield of tar, gas and char were 52.08, 28.42 and 52.7%, respectively while the lowest yield were respectively 30.50, 16.80 and 19.50%. Lignocellulosic medical waste can be a viable source of biofuels and raw materials respectively for sustainable development and for chemical industries