Rehabilitation Of Muffle Furnace

CHAPTER ONE: INTRODUCTION

• background of study
• aim and objectives
• statement of problem
• relevance / significance
• scope and limitation
• methodology

CHAPTER TWO: LITERATURE  REVIEW

2.1     Historical Background (trend) types of furnace; sources of energy etc.

2.2     review of related works

2.3     related mathematical formulae

2.4     basic application principle

2.4.1  heat transfer mode

2.4.2  Heat resistant Material

2.4.2.1 Retractories (types)

2.4.2.2        TYPES OF REFRACTORIES

• Fireclay
• High alumina
• Chromites
• Silica bricks
• Zirconia
• Oxide
• Monolithic

2.4.4           heat losses and furnace lagging

2.4.4.1        insulating materials

• Ceramic fibre
• Natural fibre
• Locally available insulating material e.g kaolin, sawdust, ash charcoal dust, sodium silicate, fire cement, etc.

Thermal properties of an insulating materials, e.g.

• Thermal conductivity
• Specific heat capacity
• Thermal diffusivity

CHAPTER ONE: INTRODUCTION

• background of study

A furnace is known as a device in which heat is generated and transferred to materials with the object of bringing about physical and chemical changes. The source of heat is usually combustion of solid, liquid or gaseous fuel, or electrical energy applied through resistance heating (Joule heating) or inductive heating.

The case of muffle furnace, it is refer to as a box that is loaded from the front and is capable of maintaining high temperatures (95⁰C-1600⁰C) within. Both ovens and kilns (thermally insulated chamber) qualify as Muffle Furnaces by this definition. In historical usage it is a furnace in which the subject material is isolated from the fuel and all of the products of combustion including gases and flying ash. After the development of high-temperature electric heating elements and widespread electrification in developed countries, new Muffle Furnaces quickly moved to electric designs.

Muffle Furnaces use open coil heating elements on both sides of the heating chamber to allow fast heating with minimal temperature gradient. This energy efficiency is enhanced through the use of high thermal-efficient ceramic insulation surrounding the chamber. The free-floating, ceramic fiber door includes a chamber plug that prevents heat loss around the door by totally sealing when the spring-loaded door is closed. This furnace have a door safety switch which cuts power to the elements if the door is opened during use.

• aim and objectives

The aim of the work is to rehabilitate a heat treatment muffle furnace in which the subject material is isolated from the fuel and all of the products of combustion, including gases and flying ash. Objective of the project are:

1. to reduce the risk of fire and explosion that is common to other type of furnace
2. produce a furnace that allows rapid high-temperature heating

• automatically control the temperature of a furnace.

1. To build a furnace with a temperature up to Maximum: 16000 C
   • Statement Of Problem

this device was carried out in other to overcome problem discovered in other types of oven such as undurability, unreliability and short usuage time due to the kind of materials they are made. The muffle furnace is usually heated to desired temperatures by conduction, convection or blackbody radiation from electrical resistance heating elements. This muffle furnace is made of standard quality materials which make it durable, reliable and perfect for long time use. The outer case or cabinet of this muffle furnace is made of thick materials. The case is painted with stove enable that keeps the unit rust free.  For heating elements class A-1 heating wires are used in coil form and embedded in high grade refractory cement and backed by high temperature ceramic wool insulation. This helps in keeping the unit safe from loss of energy and also ensures uniform distribution of heat.  The door comes with strong lid which can be used to open and close the unit at any temperature. The temperature control unit comprises of regulator control in front of the unit with pilot lamps

• relevance / significance

This device can be use industrially with an externally heated chamber, the walls of which radiantly heat the contents of the chamber, so that the material being heated has no contact with the flame. Muffle furnaces are most often utilized in laboratories as a compact means of creating extremely high-temperature atmospheres. They are employed to test the characteristics of materials at extremely high and accurate temperatures.

In a crafty applications, this device can be use in hardening enamel coating onto clay, firing ceramics, melting and fusing glass, soldering items together, and brazing. Muffle furnace can also be used in nutritional Analysis, making it possible to determine the relative proportions of proteins, fat, carbohydrate, and water in food under study.

• scope and limitation

The furnace chamber is heated by Electric Resistance Elements and is insulated with Ceramic Fiber Insulation. The controller is located under the Furnace Chamber and is well insulated from the heat generated in the Furnace Chamber. A door safety switch removes power to the heating elements whenever the Furnace door is opened. The temperature is controlled by one of three types of controllers.

A Muffle Furnace most frequently uses the heating method known as Conduction, which involves heating a surface and allowing the heat to radiate into nearby areas such as holding cavity. However, some Muffle Furnaces use Convection heating instead, which involves the circulation of hot air and sometimes Black Body Radiation method too.

• methodology

In the course of carrying this study, numerous sources were used which most of them are by visiting libraries, consulting journal and news papers and online research which Google was the major source that was used.