Effect of using vegetable oils as quenching media for pure commercial aluminium

This paper presents the effects of rate of heat extraction by groundnut, melon, palm kernel, shea butter and palm oils on the mechanical properties of various samples of pure commercial aluminium heat treated at 200°C, 250°C, 300°C and 350°C. Muffle furnace equipped with digital thermometer and thermocouple was used for the heat treatment. Tensile strength and hardness tests were carried out using Instron Universal Tester and Vickers hardness methods, respectively. Results obtained from the experiment were presented graphically. The results showed that palm kernel oil cools faster at 200°C and 250°C, while palm oil and shea butter oil quench faster at 300°C and 350°C, respectively. Palm kernel oil offers the highest elongation at 200°C, while at 350°C shea butter oil gave the best result. The best among the bio-quenching oils in providing good ductility is shea butter oil at 200°C, while at 300°C and 350°C groundnut oil give the best result. Highest hardness values were obtained from samples quenched in melon oil between 200°C-300°C. However, these values decreased with increased heating temperature probably due to density and viscosity variation with temperature rise. Similar observations were made on most of other samples quenched in other bio-quenching oils used in this experiment. This study shows that these locally available vegetable oils have promising potentials to serve as a possible replacement for non-biodegradable mineral oils in many applications

Influence of Torrefaction on Lignocellulosic Woody Biomass of Nigerian Origin

Torrefaction process is a thermal treatment that can improve quality of lignocellulosic biomass into a carbon-rich and hydrophobic feedstock which is applicable as fuel and metallurgical reductant. Biomass (Melina and Teak wood) of Nigerian origin was subjected to mild (240o C) and severe (300o C) torrefaction treatment at different residence times (30 and 60 min) and particle sizes (+0.5 - 2 mm and +4 - 6.35 mm). Raw biomass and biochar from torrefaction were subjected to proximate, ultimate, higher heating value and SEM analyses. The mass yield obtained for mild treatment conditions for both biomass was in the range of 72 - 84 (wt. %) compared to 40 - 54 (wt. %) under severe treatment conditions. However, 33 - 56 % increment in higher hating value was observed for severe treatment conditions as against 11 - 17 % of mild treatment condition. This ultimately led to a 60 - 72 (wt. %) energy yield for severe treatment conditions and 73 - 94 (wt. %). The fixed carbon content increased from the range of 8 - 11 (wt. %) to 20 - 61 (wt. %) after torrefaction. The volatile matter content under mild condition was reduced by 7 - 10 % for both biomass as against 41 - 47 % under severe treatment condition. The fuel ratio increased from 0.11 and 0.15 for Melina and Teak woods respectively to a range of 0.22 - 0.25 for mild treatment conditions and 0.97 - 1.75 for severe treatment condition. The H/C and O/C atomic ratios of biochar were lowered towards that of sub-bituminous coal and peat. A honey-comb-like structure with cylindrical holes were observed for biochar compared to the fibrous and spongy nature of the raw biomass. Biomass of Nigerian origin were improved under torrefaction and thus can be suitable as feedstock in thermal or metallurgical applications

Analysis of clean coal technology in Nigeria for energy generation

Abstract: An analysis of clean coal technologies for the recovery of energy from Nigerian coals was carried out. The coal mines studied are Onyeama, Ogwashi, Ezimo, Inyi, Amasiodo, Okaba, Lafia-Obi, Owukpa Owukpa, Ogboyoga and Okpara. The estimated reserves of the ten coal deposit amount to 2.1 Gt, which is about 84 % of the total coal reserves of the country 2.5 Gt of coal Nigeria. The key clean coal technologies studied are Ultra-Supercritical Combustion (USC), Supercritical-Fluidised Bed Combustion (FBC), Integrated Gasification Combined Cycle (IGCC) and Coal bed Methane (CBM) and the results were compared with conventional subcritical pulverised fuel combustion (PF). The total potential energy recovery from these technologies are: PF 5800 TWh, FBC 7250 TWh, IGCC 7618 TWh, and USC 8519 TWh. This indicates an increase of about 31% in the total electricity generation if USC technology is used instead of the conventional sub-critical PF technology..

PID Controller Design for Two Link Flexible Manipulator

Flexible Link Manipulator Systems (FLMs) is more favoured in the industries when compared to the rigid link manipulator, the reason for this include: their light weight, the ease with which they can be manipulated, they consume less energy because of their light weight, and they can be manipulated faster when compared to their rigid counterpart. Despite all these advantages, controlling flexible system can pose a lot of challenges because of the distributed nature of such flexible systems. In this research work, a traditional proportional, integral derivative (PID) control system was designed for two-link flexible manipulator. The two-link robot manipulator was modelled using Lagrange and assumed mode method. The control law was developed and tested in Matlab/Simulink environment. The performance of the designed controllers is evaluated in terms of input tracking capability, energy utilization, and deflection suppression and vibration control. This study shows that a simple traditional PD/PID controller can be effectively designed for two link flexible manipulators for point to point motion control and vibration suppression

Circumventing 'free care' and 'shouting louder':Using a health systems approach to study eye health system sustainability in government & mission facilities of north-west Tanzania.

BACKGROUND: Little is known about the contributions of faith-based organisations (FBOs) to health systems in Africa. In the specialist area of eye health, international and domestic Christian FBOs have been important contributors as service providers and donors, but they are also commonly critiqued as having developed eye health systems parallel to government structures which are unsustainable. METHODS: In this study, we use a health systems approach (quarterly interviews, a participatory sustainability analysis exercise and a social network analysis) to describe the strategies used by eye care practitioners in four hospitals of north-west Tanzania to navigate the government, church mission and donor rules that govern eye services delivery there. RESULTS: Practitioners in this region felt eye care was systemically neglected by government and therefore was 'all under the NGOs', but support from international donors was also precarious. Practitioners therefore adopted four main strategies to improve the sustainability of their services: (1) maintain 'sustainability funds' to retain financial autonomy over income; (2) avoid granting government user fee exemptions to elderly patients who are the majority of service users; (3) expand or contract outreach services as financial circumstances change; and (4) access peer support for problem-solving and advocacy. Mission-based eye teams had greater freedom to increase their income from user fees by not implementing government policies for 'free care'. Teams in all hospitals, however, found similar strategies to manage their programmes even when their management structures were unique, suggesting the importance of informal rules shared through a peer network in governing eye care in this pluralistic health system. CONCLUSIONS: Health systems research can generate new evidence on the social dynamics that cross public and private sectors within a local health system. In this area of Tanzania, Christian FBOs' investments are important, not only in terms of the population health outcomes achieved by teams they support, but also in the diversity of organisational models they contribute to in the wider eye health system, which facilitates innovation

Assessment of Metallic Contaminants in Grinded Millet using Domestic Grinding Machine

In this study, the quantity of metallic contaminants extracted from grinded millet was evaluated. The millet was grinded in three different forms; wet, paste, and dry forms for up to 3 minutes using locally fabricated grinding machine with cast grinding discs. Separate grinding discs were used for different millet forms, while the same quantity of millet, 1 kg, was used throughout the experiments. The millet was soaked for 24 hours before grinding in order to obtain wet and paste forms of the millet. Metallic contaminants were carefully extracted from the grinded millet using magnetic bed along with sedimentation and decantation. The extracted materials were then quantified to ascertain the food form that produces the highest amount of metallic contaminants. Also, the wear rate of the grinding disc was also determined with respect to the grinding time. The results show that the wet form has the highest amount of metallic contaminants of about 1.397 g followed by the paste form with 1.075 g. The dry form has the least value corresponding to 0.945 g. The grain sizes of the metallic contaminants were calculated to be 12.095 nm for the wet form, 8.056 nm for paste form while the dry form has the smallest grain size of 3.124 nm. The results revealed that metallic contaminants are always contained in grinded food processed with local grinding discs. Thus, materials with better wear resistance should be selected for production of grinding discs to be used for food processing

Thermal and compositional properties of treated Tectona grandis

A torrefaction parametric study was conducted on Tectona grandis at varying torrefaction temperatures (240-300 degrees C), residence times (30-60 min), and particle sizes (2-6 mm) using a full factorial design (FFD). Optimum parameters were obtained through numerical optimization using the response optimizer in Minitab 17. These parameters were used to produce fuel with maximum mass yield (MY), higher heating value (HHV), and energy yield (EY). Proximate, ultimate, and HHV analyses were carried out on the raw and torrefied Tectona grandis samples based on ASTM standards, while Fourier transform infrared (FTIR) spectroscopy was used to determine the various functional groups present in the samples. The optimum parameters obtained were temperature (260 degrees C), residence time (60 min), and particle size (< 2 mm), while the maximum MY, HHV, and EY of the fuel are 70.20%, 23.10 MJ/kg, and 88.07%, respectively. The results revealed that torrefaction temperature has the largest effect on the properties of the Tectona grandis compared to other factors based on FFD analyses. There was a reduction in the volatile matter and moisture content of the raw biomass from 79.26 to 54.90% and 7.23 to 2.87%, respectively, while the fixed carbon and HHV increased from 11.73 to 40.43% and 18.73 to 23.10 MJ/kg, respectively, after torrefaction. The FTIR spectra showed a reduction in O-H and C-O bonds and an increase in C-C and C=C bonds in the torrefied samples compared to the raw samples. The thermochemical properties of the torrefied samples are better than those of the raw biomass

The Ignitability, Fuel ratio and Ash Fusion Temperatures of Torrefied Woody Biomass

The impact of torrefaction temperature on the ignitability, fuel ratio and ash fusion temperatures of two tropical deciduous woods (Teak and Melina) were investigated in a setup of tubular furnace. The properties considered are calorific value, fuel ratio, ignitability index, ash compositions and ash fusion temperatures of the biomass. Six different temperatures (220, 240, 260, 280, 300 and 320 °C) at 60 min reaction time were considered. The results indicated that as torrefaction temperature increased, the calorific value, fuel ratio and ignitability index of the biomass also increased. The ignitability index of biomass (40–63) was better than the value (35) recommended for fuel applicable in thermal plants for power generation. The ash compositional analysis revealed that there was no variation in the quantity of SiO2, Al2O3, CaO along with other minerals for the raw and torrefied biomass. This implied that the temperature up to 320 °C has no significant impact on the compositions of biomass ash during torrefaction. The ash fusion temperature test showed that the biomass ash softens at 1200 °C and finally fused at 1300 °C. The study concluded that an increase in torrefaction temperature increases the thermal properties of the torrefied biomass without affecting the compositions of biomass ash or lowering the ash fusion temperatures

Ash analyses of bio‑coal briquettes produced using blended binder

The behaviour of ash of fuel afects its thermal efciency when in use. The ash analyses of bio-coal briquettes developed from lean grade coal and torrefed woody biomass have received limited intensive study. Therefore, the present study aims at analysing the ashes of briquette made from lean grade coal and torrefed woody biomass using blended coal tar pitch and molasses as the binder. Bio-coal briquettes were produced from coal and torrefed biomass in various hybrid ratios. Ashing of various briquettes was done in a mufe furnace at 850 °C for 3 h. Mineral phases of the ash were identifed using an X-ray Difractometer (XRD), while the mineral oxides were obtained using an X-ray Fluorescence Spectrometer. The AFT700 Furnace was used with its AFT700 software to evaluate the ash fusion temperatures of the ashes. The XRD patterns look similar, and quartz was found to be the dominant mineral phase present in the raw coal and bio-coal briquettes. The SiO2 (57–58%), Al2O3 (19–21%), and Fe2O3 (8–9%) were the major oxides observed in the ashes. The fnal fusion temperatures of the ashes range from 1300–1350 °C. The compositions of the ashes of the bio-coal briquettes are classifed as detrital minerals. It was concluded that the addition of torrefed biomass (≤10%)and blended binder (≤ 15%) to coal gave a negligible impact on the ashes of the resultant biocoal briquettes