ABSTRACT
The increasing demand for cement due to urbanization growth in Africa countries may result in an upsurge of pollutants associated with its production. One major air pollutant in cement production is nitrogen oxides (NOx) and reported to cause serious damage to human health and the ecosystem. The operation of a cement rotary kiln NOx emission was studied with plant data using the ASPEN Plus software. It is essential to understand the effects of calciner temperature, tertiary air pressure, fuel gas, raw feed material, and fan damper on NOx emissions from a precalcining kiln. In addition, the performance capability of adaptive neuro-fuzzy inference systems and genetic algorithms (ANFIS-GA) to predict and optimize NOx emissions from a precalcining cement kiln is evaluated. The simulation results were in good agreement with the experimental results, with root mean square error of 2.05, variance account (VAF) of 96.0%, average absolute deviation (AAE) of 0.4097, and correlation coefficient of 0.963. Further, the optimal NOx emission was 273.0 mg/m3, with the parameters as determined by the algorithm were calciner temperature at 845 °C, tertiary air pressure - 4.50 mbar, fuel gas of 8550 m3/h, raw feed material 200 t/h, and damper opening of 60%. Consequently, it is recommended that ANFIS should be combined with GA for effective prediction, and optimization of NOx emission in cement plants.
Subject(s)
Air Pollutants , Ecosystem , Humans , Air Pollutants/analysis , Algorithms , Software , Nitrogen OxidesABSTRACT
This paper analyzes the adoption of an off-grid hybrid renewable energy system (HRES) for a high-rise building owned by a public institution in Nigeria. The analysis is based on the comparison between the use of a single criterion and multiple criteria in the selection of the most feasible energy system. The proposed HRES comprises of a wind turbine, diesel generator, photovoltaic (PV), and battery storage system. Hybrid optimization of multiple energy resources (HOMER) software was used to design the HRES for a case study (based on a single criterion-total net present cost), while Evaluation Based on Distance from Average Solution (EDAS) method was used to evaluate the effect of choosing an optimal system based on multiple criteria. Based on the simulations conducted with HOMER, eight feasible HRES (ES1-ES8) were identified. When the feasible HRES were ranked based on total (NPC), the optimal configuration comprises 70 kW PV modules, 20 kW diesel generating set, 40 kW converter, and 70, 3000 Ah batteries. The results obtained from the optimization process were subjected to a multi-criteria analysis based on sustainability principles. The ranking of the first two systems (ES1 and ES2) returned by single criterion (total NPC) remained the same, while changes were observed in the ranks of the remaining systems (ES3-ES8). This modular feasibility study shows that it would be economical to power the entire university using HRES. It is expected that this study would help the university communities and other stakeholders make informed decision during the planning stage of similar projects.
Subject(s)
Electric Power Supplies , Universities , Nigeria , Renewable Energy , SoftwareABSTRACT
Rubber seed oil (RSO) (Hevea brasiliensis) was extracted from rubber seeds by chemical means. The effect of temperature on the oil yield was investigated. The experiment suggested that the maximum yield of the oil occurs at 60 °C. This is a result of the proximity to the boiling point of n-hexane, which is about 68 °C. Epoxidized and hydroxylated RSOs were further synthesized by performic acid generated in situ by the reaction of formic acid with 30% hydrogen peroxide. The physiochemical properties of the epoxidized rubber seed oil (ERSO) and hydroxylated rubber seed oil (HRSO) were determined. A separate study was also carried out on castor seed oil (CSO). The improved products were characterized with respect to their configuration and properties. Spectroscopic analysis was carried out on the oil base stocks (RSO, CSO, ERSO, and HRSO). All of the experimental findings were compared with one another. The lubricating properties of CSO and HRSO are further studied as a result of their common hydroxyl nature to ascertain their suitability as a lubricant base. Both oils can be categorized as a nondrying oil with saponification values of 179.52 and 255.25 mgKOH/g, respectively, and as such possess advantageous properties for industrial application. When compared to one another, HRSO appears to be a more effective choice as a lubricant base. This is because of its higher viscosity index of 380.65. The outcomes of this study indicate that hydroxylated and epoxidized RSO with high oxirane content can be synthesized concurrently by one-pot multistep reactions.
ABSTRACT
The use of ozone, chloramine and chlorine dioxide for water treatment results in the formation N-nitrosamines in the treated water. These groups of chemicals and other nitrogen-containing compounds have been described as disinfection by-products (DBPs) which are known for their toxicity. Nitrosamines are a potential source of nitric oxide (NO) which can bind with metals present in the sample matrix leading to formation of metal - nitrosyl complexes and dissolved metals have the potential to increase the total nitrosamines in water. This phenomenon has not received the desired attention and determination of metal-nitrosyl complexes lack standard analytical technique. Chromatography linked to various detectors is the commonest of the techniques for nitrosamine analysis but it is beset with reduced sensitivity as a result of inappropriate choice of the column. Incidentally, chromatographic techniques have not been really adapted for the analysis of metal-nitrosyl complexes. Therefore, there is need for the survey of existing techniques vis-à-vis metal-nitrosamine analysis and to suggest possible areas for method optimization.
ABSTRACT
The purpose of this review is to establish and classify the diverse ways in which evolutionary computation (EC) techniques have been employed in water demand modelling and to identify important research challenges and future directions. This review also investigates the potentials of conventional EC techniques in influencing water demand management policies beyond an advisory role while recommending strategies for their use by policy-makers with the sustainable development goals (SDGs) in perspective. This review ultimately proposes a novel integrated water demand and management modelling framework (IWDMMF) that enables water policy-makers to assess the wider impact of water demand management decisions through the principles of egalitarianism, utilitarianism, libertarianism and sufficientarianism. This is necessary to ensure that water policy decisions incorporate equity and justice.
