Abstract
In this study, energy audit of a wheat processing plant in Rivers State, Nigeria has been carried out. A walked-through energy audit method was undertaken to identify the major sources of energy in use, identify the lapses in energy usage, identify areas to improve energy usage, determine the level of energy consumption of the various energy sources and recommending policy measures that will enhance energy savings in the industry. The analysis showed that eight defined unit operations were required for the production of wheat flour; Truck Loading, Intake or Storage, Cleaning, Tempering or Conditioning, Holding Bin, Milling, Finished Product and Packaging. The types of energy used were electrical, thermal (diesel and gas), and manual energies with proportions of 14.63%, 85.31% and 0.05% respectively of total energy input. Average energy intensity was estimated to be 1.3GJ/tonnes for the production of wheat flour for the 5 years (2011-2015) study period. The most energy intensive operation was identified as the milling process with percentage energy input of 44.39% (123837.60MJ) followed by Finished Product Storage process with percentage energy input of 36.17% (100885.92MJ). It was observed that the industry under review did not sufficiently utilize energy as the energy used ratio is below 1. This was as a result of some factors that contributed to energy waste and energy use inefficiency in the industry. Among these factors are: electric motor that dissipate much heat, use of electric motors that have been rewound more than twice and generation of electricity more than needed in the industry by some generators. The exergy analysis showed that the roller dryer accounted for the major loss in the process with an inefficiency of 44.8%. The useful work was 5.3kJ; exergy loss expended is 15.68kJ in the roller dryer. The study concluded that energy is not sufficiently utilized in the industry resulting in high energy waste and high pricing of wheat flour products.
Highlights
Energy is a fundamental aspect of our modern day economy and a vital input in almost all production process in any industry
Energy audit was conducted on a wheat processing plant; Crown Flour Mill Ltd located in Rivers State, Nigeria
The study reveals that the energy sources in use are electrical, thermal and manual energies accounting for 25.42%, 73.01%, and 1.57% of total annual energy consumption, respectively, indicating that the industry uses mainly generating set for electrical power generation during production
Summary
Energy is a fundamental aspect of our modern day economy and a vital input in almost all production process in any industry. The total energy consumption of the industrial sector of developed countries contributes to around 30 to 40 per cent of total energy demand [1]. The most important resource to both human beings and industrial activities is energy and energy consumption was projected to increase by 33 per cent from 2010 to 2030 in the world [2]. The aim of this study is to identify the energy inefficiencies in unit operations of a wheat processing plant as a means of improving the efficiency of the plant. The objectives of this study are: to study the pattern of annual energy consumption and utilization in the wheat flour processing plant, to identify the source of energy waste in the plant, and to establish appropriate methodologies for effective energy savings in the industry
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