Project Abstract

ABSTRACT 

Five coal samples from Odagbo (Kogi State), Owukpa (Benue State), Ezimo (Enugu State), Amansiodo (Enugu State) and Inyi (Enugu State) weresubjected to proximate analysis, ultimate analysis, calorific value determination, petrographic and thermogravimetric analysis to determine their suitability for power generation. Tests were carried out at the laboratories of Advanced Coal Technology, South Africa (now Bureau Veritas Testing and Inspections South Africa, BV-TISA) and the Institute of Applied Materials of the University of Pretoria. Based on analysis of results of tests carried out, Amansiodo coal is a bituminous, low sulphur and medium ash coal; while Owukpa coal is a sub-bituminous A, low sulphur, low ash coal rich in huminites. In addition, Odagbo coal is a sub-bituminous B, medium sulphur, low ash coal rich in huminites; Ezimo coal is a sub-bituminous C, low sulphur, high ash coal; while Inyi coal is a sub-bituminous C, low sulphur, high ash coal.Between Odagbo and Owukpa sub-bituminous coals, Owukpa has a lower ignition temperature (283.63oC) due to its higher volatile matter content (39.1%). However, Ezimo sub-bituminous coal, which has a lower volatile matter (31.1%) unexpectedly has the same ignition temperature as Owukpa (283.63oC) due to its higher liptinite content (7.2%) when compared with that of Owukpa (2.9%). The five (5) coal samples analysed can be used for power generation using circulating fluidised bed combustion (CFBC) technology due to its tolerance of a widevariety of coals and particle sizes. Amansiodo coal is suitable for power generation using pulverised coal combustion technology based on comparison of its gross calorific value (27.48MJ/kg), ash content (8.6%), inherent moisture content (5.4%), sulphur content (0.92%), etc with requirements published by coal-fired power plant operators. Gross calorific values, inherent moisture and contents of Odagbo, Owukpa, Ezimo and Inyi sub-bituminous coals make them largely suitable for pulverized coal combustion when vi compared with the coal fuel used for the Genessee Phase 3 power station in Canada. The ease of combustion of the coal samples in decreasing order is Odagbo, Owukpa, Inyi, Ezimo and Amansiodo. The ignition temperatures of the coals increase with decreasing volatile matter content, their calorific values are strongly correlated with the fixed carbon, elemental carbon, volatile matter and hydrogen contents in decreasing order.

Project Overview

1.1 INTRODUCTION

Power generation in any country is very essential to its economic growth, Nigeria generates about 4,000 megawatts(MW) of electricity (Ediri, 2014), but this is deficient as the country still faces the challenge of epileptic power supply, it is expected that power generation reaches 40,000 megawatts(MW) in the year 2020 (Ediri, 2014), to achieve this feat the government has planned the construction of various power generating stations of which coal would be a vital raw material used in some of these plants, although generation of energy from coal is accompanied by the emission of greenhouse gases, the development of clean coal technologies have helped to reduce this emissions.Coal which is a product of long periods of accumulation and subsequent physical and chemical alteration of plant material is an organic rock (as opposed to most other rocks in the earth's crust, such as clays and sandstone, which are inorganic; it contains mostly carbon (C), but it also has hydrogen (H), oxygen (O), sulfur (S) and nitrogen (N), as well as some inorganic constituents (minerals) and water (H2O). (Radovic, 2009) Different types of coals are classified based on their composition of these constituent elements, based on this coal is classified as lignite, subbituminous, bituminous and anthracite. the combustion of coal under specified conditions leaves behind a residue known as ―ash‖ which is composed mainly of oxides and sulphate depending on the source of the coal sample. (Folahan , 2012).

The combustion of coal produces sulphur and some other gases and a solid residue known as coal ash or fly ash. Fly ash is either deposited as dry or hydraulic ash, the sulphur content of coal varies considerably with the nature and origin of the fossil deposits (Folahan , 2012) the utilization of coals for both energy production and various coal conversion processes is limited by the presence of sulphur in the coal, sourcing for the right type of coal and inconsistency in composition. Many of these plants will not be able to source for coal that meet up to their specification and will have to combine samples available to them to obtain the required quality of coal. The high sulphur dioxide emissions caused by the utilization of coals as a major fossil fuel leads to worldwide environmental problems. When coal is burnt its sulphur content combines with oxygen to form sulphur dioxide (SO2), which contributes to both pollution and acid rain. Acid rain resulting from SO2 has a harmful effect on agriculture and destroys the ecological balance. Also naturally occurring elements in the environment become part of the coal structure through the coalification process. The use of large quantity of coal results in significant emissions of these trace elements, although these trace elements are present in small amounts in the coal. Another serious problem of sulphur in coalis the formation of clinker in furnaces. The causes of clinker formation are low quality coal having low gross calorific value, more ash content, high mineral content, low fusion temperature of ash below 1500 C, and over-firing of the molten slag.

The presence of sulphur in coal also reduces the quality of metallurgical coal (Folahan , 2012). Blending of coals results in a combination of characteristics from each of the

individual coals in the blend. Some coal characteristics, such as ash, sulphur and

moisture content, are additive and can be calculated from the proportions of

the different coals in the blend, it is therefore necessary to know the characteristics of the individual samples and that of the final blend before it is used in any power plant, this will enable a plant to understand the advantage and problems related to each blend of coal. The work done involves the chemical andthermo-gravimetric analysis of maiganga and okaba coal blend.