Design, construction and performance evaluation of a fixed bed pyrolysis system

Project Abstract

<p> A fixed bed pyrolysis system has been designed and constructed for obtaining liquid fuel<br>from palm kernel shell. The major components of the system are fixed bed reactor and<br>condensate unit. The palm kernel shell in particle form was pyrolized in an externally<br>heated 90mm diameter and 360mm high fixed bed reactor. The reactor is heated by means<br>of a rectangular shape manual forge blower with charcoal as the energy source. The<br>products are char, oil and gas. The parameters varied are feed particle size, reactor bed<br>temperature and running time. The reactor bed temperature was found to influence the<br>product yields. The maximum liquid yield was 38.67wt % at 4500C for a feed particle size<br>of 1.18mm with a running time of 95minutes. The maximum char yield was 70.67wt% at<br>5500C for a feed particle size of 5mm with a running time of 120minutes. The calorific<br>value of the palm kernel shells (22.81 MJkg-1) and bio-oil (43.19MJkg-1) were determined.<br>The reactor efficiency was evaluated at various temperatures. Maximum efficiency of<br>73.21% indicated that the reactor is efficient enough to produce bio-oil. The bio-oil<br>products were analysed by Fourier Transform Infra-red Spectroscopy (FTIR) and Gas<br>Chromatography Mass Spectrometry (GCMS). The FTIR analysis showed that the bio-oil<br>was dominated by phenol and its derivatives. The phenol, 2-methoxy-phenol and 2, 6-<br>dimethoxyl phenol that were identified by GCMS analysis are highly suitable for<br>extraction from bio-oil as value-added chemicals. The highly oxygenated oils need to be<br>upgraded in order to be used in other applications such as transportation fuels.<br>vii <br></p>

Project Overview

<p> INTRODUCTION<br>1.1 Background of the Study<br>Uninterrupted energy supply is a vital issue for all countries today. Future economic<br>growth crucially depends on the long-term availability of energy from sources that are<br>affordable, accessible, and environmentally friendly. Security, climate change, and public<br>health are closely interrelated with energy (Ramchandra and Boucar, 2011). The standard<br>of living of a given country can be directly related to the per capita energy consumption.<br>The recent world’s energy crisis is due to two reasons: the rapid population growth and the<br>increase in the living standard of societies. The per capita energy consumption is a measure<br>of the per capita income as well as a measure of the prosperity of a nation (Chikaire et al.,<br>2015).<br>Energy supports the provision of basic needs such as cooked food, a comfortable living<br>temperature, lighting, the use of appliances, piped water or sewerage, essential health care<br>(refrigerated vaccines, emergency and intensive care), educational aids, communication<br>(radio, television, electronic mail, the World Wide Web), and transport. Energy also fuels<br>productive activities including agriculture, commerce, manufacturing, industry, and<br>mining. Conversely, lack of access to energy contributes to poverty and deprivation and<br>can contribute to the economic decline. Energy and poverty reduction are not only closely<br>connected with each other, but also with the socioeconomic development, which involves<br>productivity, income growth, education, and health (Nnaji et al., 2010).<br>The high rate of extracting the crude oil from the earth-crust demands for an alternative<br>and dependable source of obtaining energy (Rajput, 2005). This alternative is the energy<br>derived via pyrolysis (a thermal decomposition process that occurs at moderate<br>2<br>temperatures with a high heat transfer rate to the biomass particles and a short hot vapour<br>residence time in the reaction zone) of agricultural and forest residues (generally called<br>biomass). Biomass has been recognized as a major renewable energy source to supplement<br>declining fossil fuel sources of energy. It is the most popular form of renewable energy and<br>currently biofuel production is becoming very much promising. Transformation of energy<br>into useful and sustainable forms that can fulfil and suit the needs and a requirement of<br>human beings in the best possible way is the common concern of the scientists, engineers<br>and technologists. In this contest, bio fuels can be realised through fixed bed pyrolysis<br>system using palm kernel shells as biomass. Fixed bed pyrolysis is more attractive among<br>various thermo-chemical conversion processes because of its simplicity and higher<br>conversion capability of biomass and solid wastes to yield char, liquid and gases (Hossain<br>et al., 2014).<br>1.2 Statement of the Research Problem<br>From the literature reviewed, it is obvious that a lot of research works have been conducted<br>on fixed bed pyrolysis system powered by electric heater. However, it is obvious from the<br>review that fixed bed pyrolysis system powered by electric heater can only be efficiently<br>used where there is steady electricity supply which is the major limitation of this system<br>(especially in Nigeria).<br>The use of stainless steel for the construction of the reactor has a significant effect on the<br>cost of the pyrolysis products. Therefore, there is a need to source for alternative material<br>to minimize the cost at optimum production.<br>3<br>1.3 The Present Research<br>The current work focuses on the design, construction and performance evaluation of a<br>fixed bed pyrolysis system, which will use palm kernel shells to produce bio-fuels. The<br>bio-oil produced can then be used to generate heat and power from small stationary diesel<br>engines, gas turbines and boilers. The agricultural by-products include maize cobs,<br>groundnut shells, palm kernel shells, rice and millet husks, millet stalks, sorghum stalks,<br>sugar cane bagasse, maize stalks and cotton stalks among others. However, this research<br>will focus on palm kernel shells because of its availability.<br>1.4 Aim and Objectives of the Research<br>The aim of this research is to design and construct an externally heated fixed bed pyrolysis<br>system for the production of alternative liquid oil from palm kernel shells.<br>Therefore, the specific objectives of this research are to:<br>i. design a fixed bed pyrolysis system.<br>ii. construct the fixed bed pyrolysis system.<br>iii. evaluate the performance of the fixed bed pyrolysis system to determine its<br>effectiveness in bio-oil production.<br>iv. characterise the bio-oil produced from the fixed bed pyrolysis system using<br>FTIR and GCMS analyses.<br>1.5 Justification of the Study<br>Nigeria is blessed with abundant renewable energy resources such as hydroelectric, solar,<br>wind, tidal, and biomass, there is a need to harness these resources and chart a new energy<br>future for Nigeria. To enhance the developmental trend in the country, there is every need<br>to support the existing unreliable energy sector with a sustainable source of power supply<br>through pyrolysis of biomass.<br>4<br>There are several benefits of introducing electricity to rural communities. While obvious<br>reasons include social gains like lightening, cooking and water pumping, electricity will<br>help to stem the flow of rural-urban migration which is a common problem in many<br>developing countries like Nigeria. Introduction of electricity also helps to provide<br>productive employment in rural areas thereby creating a positive impact on economic as<br>well as social growth. Fixed bed pyrolysis when combined with a boiler can provide<br>efficient and affordable source of energy thereby boosting rural education and<br>development, since it uses agricultural waste as a fuel source. Bio-oil generated can either<br>be used for electricity production in a gas turbine or generate steam in a boiler.<br>1.6 The Scope of the Research<br>The scope of this research is:<br>i. Design, construction and performance evaluation of a fixed bed pyrolysis<br>system, which will use palm kernel shells as feed materials to produce biofuels.<br>ii. The emphasis of the study is on the production of a liquid fuel from 1.5kg per<br>sample of palm kernel shells using fixed bed pyrolysis system. The char<br>product will be also quantified.<br>5 <br></p>