Talon Garikayi c056634k- Final Automated Lubrication System Project for Simbi Plant With Cover Page...

CHINHOYI UNIVERSITY OF TECHNOLOGY

FACULTY OF ENGINEERING

DEPARTMENT OF MECHATRONICS ENGINEERING

ATTACHMENT PROJECTATTACHMENT PROJECT

FOR

TALON GARIKAYI TALON GARIKAYI

REG NO: CO56634K

AT

S.I.M.B.I. PVT. LTD

(STEELMAKERS ZIM PVT LTD GROUP OF COMPANIES) MASVINGO BRANCH

____________________________________________________________________Talon Garikayi B.Eng Honours Degree in Mechatronic Engineering, Chinhoyi University of Technology- Automatic Lubrication System Project.

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TITLE: AN AUTOMATED LUBRICATION SYSTEM PROJECT DONE AT

STEELMAKERS (PVT) LTD –SPONGE IRON PRODUCTION DIVISION (SIMBI

BRANCH) BY TALON GARIKAYI (C056634K).

THE PROJECT WRITE IS SUBMITTED IN PARTIAL FULFILMENT OF THE

REQUIREMENTS OF A BACHELOR OF ENGINEERING HONOURS DEGREE IN

MECHATRONIC ENGINEERING TO THE DEPARTMENT OF MECHATRONIC

ENGINEERING, CHINHOYI UNIVERSITY OF TECHNOLOGY UNIVERSITY

(2008).

__________________________________

PROJECT SUPERVISOR’S SIGNATURE

MR I. MUCHIMWE

GROUP INSTRUMENTS ENGINEER


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ACKNOWLEDGEMENTS

I want to sincerely thank Mr. Mpofu, Mr. Ncube and Mr. Towera the Instruments

Technicians for their support during my project research. I also want to thank the

Electrical Manager Mr. Siriheri for his unrufflable diligence and ability to understand my

questions during research although there seems to be some communication problems. Mr.

Munyariwa was always there for my questions during my period of internship at the

Electrical department. To a greater extent I want to thank Mr. Chigova the Mechanical

Supervisor for his rendered support during my time at the Mechanical Department.

Lastly I would like to thank Mr. I Muchimwe (Instruments Engineer), Mr. Jemias

Chakonda and Mr. C. Madiro (Student Engineers from NUST) for their support during

the whole research and my time as a trainee at SIMBI. Their ability to spend valuable

time during discussions can be partly attributed for the lengthy of this project.

This report would not have been complete without the support of my family and Mrs.

Linda Makura.


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CONTENTS PAGECONTENTS PAGE

Contents PagesAcknowledgements iAbstract iiChapter One: Introduction 1

Chapter Two: Literature Review 22.0 Introduction to literature review 22.1Tribology 32.2 Fundamentals of Tribology 42.3 Grease as a Lubricant 52.5 Lubrication 82.4Valves 9

Chapter Three: Conceptual Designs and analysis from Chapters 4 to 9 153.0 Introduction 15

3.1The Design Matrix table 15

Chapter Four: Analysis of Chosen Solution4.1 The Intelligence 174.2 SCADA system of the Project 20

4.3 Automation system of the Project. 214.4 Human Machine Interfacing

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Chapter Five: Analysis of Chosen Solution5.0 The VersaMax Controller 255.1 Introduction 25

5.2 Controller Details265.3 Schematic representation of the PLC 275.4 The Control 29

Chapter Six: Analysis of Chosen Solution

6.0 The Main PLC Components 336.1 The CPU Details

33 6.2 The Hardware Configurations 33


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Chapter Seven: Analysis of Chosen Solution 527.1 Pneumatic Grease Pump 527.2 The Pressure Regulator 537.3 Pressure Calculations 537.4 Justification of Chosen Solution 54

Chapter Eight: Analysis of Chosen Solution

8.0 The Pressure Transmitter 568.1 The Honeywell ST300 Pressure Transmitter

56 8.2 Installation of ST300 588.3 Valve Orientation 598.4 Pipe Installation 60

8.5 Justification of Chosen Solution618.6 The Air Compressor 628.7 The Lubricant Tank 63

Chapter Nine: Analysis of Chosen Solution

9.0 The Control System and Philosophy of the project 35

9.1 Manual mode 369.2 Auto Mode 369.3 De-Int. mode 36

Chapter Ten: Programming the Controller

10.0 PLC Programming 3710.1 Ladder Logic Programming Software 3810.2 Schematic representation of the control system components 42

Chapter Eleven: The Actuator

11.1 Introduction to Valves 4311.2 Butterfly Valve as possible solution 43

11.3 Solenoid Valve as a Chosen solution 4611.4 Justification of Chosen Solution 50

Chapter Twelve: Project Calculations 64

Chapter Thirteen: Schematic wiring representation of the project 69

Chapter Fourteen: Interfacing with SCADA CIMPLICITY Software 71


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Chapter Fifteen: Maintainability 75

Chapter Sixteen: Recommendations 76

Chapter Seventeen: References 77

Chapter Eighteen: Conclusion 78

ABSTRACT

STEELMAKERS ZIMBABWE (PVT) LTD is a privately owned company whose main

business is the mining and beneficiation of iron ore into sponge iron and this is done at its

Sponge Iron Division- Masvingo branch. The company has two main branches here in

Zimbabwe; one in Kwekwe and Masvingo. The Kwekwe branch manufactures steel using

the sponge iron from the Masvingo branch. The company also has several other branches

in Kenya, DRC and India. The Masvingo branch mines iron ore from Glenlivet and

processes it into sponge iron and has the capability of producing 100 tones of sponge iron

per day.

During sponge iron production, a Rotary Kiln and a Rotary Cooler Discharge are some

of the main machinery. The kiln is approximately 42m in length and has lubrication is

done on its sleeves. Lubrication is done manually using a hand pump, on 21/02/2008 in

the early stages of our 5th campaign production was stopped and the Kiln was put on hold

mainly because the main drive shaft was broken. After investigations were carried out,

poor lubrication method and human negligence during lubrication was considered to be

one of the major causes.

The main goal of this project is to design an automatic lubrication system that will be

able to control the lubrication system of the Rotary Kiln sleeves and Rotary Cooler

sleeves and able to be operated from either Auto or Manual means. This will increase

productivity, decrease human intervention, and increase product quality as well as the

health and safety of the workers.


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CHAPTER 1

INTRODUCTION

The overall objective of this project is to control the lubrication system of the Rotary Kiln

sleeves and Rotary Cooler Discharge. My research focuses on automatic lubrication

methods in order to increase productivity and minimize human intervention hence

improving product quality and human safety.

SIMBI is one of the major producers in sponge iron industry in Southern Africa. For its

product to satisfy international market and become globally competitive so that it can

easily outclass already established Asian and European producers there is need for it to be

technologically advanced. The current situation in the country of foreign currency

shortages can only be improved if exporting companies like SIMBI become competitive.[2]

Product quality depends on many factors chief among them being the total time taken

from adding the raw materials to the discharge of product at the Cooler Discharge outlet,

since the kiln and the cooler rotates there is great amount of frictional force experienced

at the sleeves thereby increasing the production time. [3]

Design brief


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To design an automated lubrication system for the Rotary Kiln and Rotary Cooler

Discharge sleeves.

Justification of Problem

The problem of concern in this study is the effect of too high frictional forces on the

rotary Kiln sleeves and at the Rotary Cooler Discharge thereby increasing the load of the

drive causing the main shaft to experience and the efficiency of the rotary kiln, which is

the major unit of production in the plant.

So this study seeks to find ways of optimizing operating parameters: in particular drive

speed and production time in a way to keep the degree of metallization high while

protecting the rotary kiln from premature destruction. In particular this project seeks to

determine the optimum levels and lubricant supply that can maintain both metallization

and campaign period of the kiln high. Metallization of iron ore is the sole purpose of the

process protecting the metalliser of great importance.

Objectives

To investigate the effect of lubrication on Rotary Kiln and Rotary Cooler.

To determine the optimum lubricant supply that can affect the highest extent

of Kiln and Cooler rotation and maintain frictional force at lower levels.

To continuously monitor the lubrication system and regulate the volume of

lubricant supply as per process demand.

Limitations.


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The design was confined to the automation of lubrication system so as to minimize the

use of manual lubrication currently being used. The results obtained from the research

were accounted by operating conditions and the available instruments at the plant.

CHAPTER 2

Literature review

2.0 Introduction

“A project is a set of files used to execute a control programme.” [4]

These file are the ones that I will try to research much into, they include:

Operating System

Software Package for that support the Control system

Controller parameters and the SCADA packages

“Literature review is a process that involves finding, reading, understanding and forming

conclusions about the published research and theory on a particular topic”. [5]

The research thus used textbooks, discussions, presentations and the Internet to get

information about the subject relating to the objectives.

A number of subheadings derived from literature and other sources were gathered under

the guidance of relevance. This section focuses mainly on the main individual

instruments that are expected to be implemented on the automatic lubrication system. A

summary is given on each instrument yet they were dealt in depth on later chapters.


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2.1 Tribology

Tribology is the science and technology of interacting surfaces in relative motion. It

includes the study and application of the principles of friction, lubrication and wear. The

word "tribology" derives from the Greek τριβο ("tribo") meaning 'to rub', and ("logos")

meaning 'principle or logic'[6]

Applications

The study of tribology is commonly applied in bearing design but extends into

other almost all aspects of modern technology, even to such unlikely areas. Any

product where one material slides or rubs over another is affected by complex

tribological interactions, whether lubricated (e.g. the rotary kiln sleeves and rotary

cooler sleeves) or unlubricated (for example, Kiln outlet hood area where high

temperature sliding wear in which conventional lubricants can no longer be used

and the formation of compacted oxide layer glaze. that have been observed to

protect against wear).

The frictional resistance was the same for two different objects of the same weight

but making contacts over different widths and lengths. Also observed that the force

needed to overcome friction is doubled when the weight is doubled. [7]

2.2 Fundamentals of Tribology

The tribological interactions of a solid surface's exposed face with interfacing materials

and environment may result in loss of material from the surface. The process leading to

loss of material is known as "wear". Major types of wear include abrasion (friction),

erosion, and corrosion.


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Estimated direct and consequential annual loss to industries in Zimbabwe due to wear is

approximately 1-2% of GDP. Wear can be minimized by modifying the surface

properties of solids by one or more of surface engineering processes (also called lubricant

surface finishing for frictional or adhesive wear). [8]

Engineered surfaces extend the working life of both original and recycled and resurfaced

equipments, thus saving large sums of money and leading to conservation of material,

energy and the environment. However none of the methods of reducing friction were

used mainly because of the diameter of the kiln.

2.3 Grease (lubricant)

Although the word grease originally described the rendered fat of animals, the term is

now applied more broadly to mean a lubricant of higher initial viscosity than oil,

consisting originally of a calcium, sodium or lithium soap jelly emulsified with mineral

oil.

2.3.1 Properties

A true grease consists of an oil and/or other fluid lubricant that is mixed with another

thickener substance, a soap, to form a solid. Greases are a type of shear-thinning or

pseudo-plastic fluid, which means that the viscosity of the fluid is reduced under shear.

After sufficient force to shear the grease has been applied, the viscosity drops and

approaches that of the base lubricant, such as the mineral oil. This sudden drop in shear

force means that grease is considered a plastic fluid, and the reduction of shear force with

time makes it thyrotrophic. It is often applied using a grease gun, which applies the

grease to the part being lubricated under pressure, forcing the solid grease into the spaces

in the part. [9]


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Soaps are the most common emulsifying agent used, and the type of soap depends on the

conditions in which the grease is to be used. Different soaps provide differing levels of

temperature resistance (relating to both viscosity and volatility), water resistance, and

chemical reactivity. Powdered solids may also be used, such as clay, which was used to

emulsify early greases and is still used in some inexpensive, low performance greases.

2.3.2 Uses

Greases are employed where heavy pressure exist, where oil drip from the bearings is

undesirable, and/or where the motions of the contacting surfaces are discontinuous so that

it is difficult to maintain a separating lubricant film in the bearing. Grease-lubricated

bearings have greater frictional characteristics at the beginning of operation. Under shear,

the viscosity drops to give the effect of an oil-lubricated bearing of approximately the

same viscosity as the base oil used in the grease. Lithium-based greases are the most

commonly used; sodium and lithium based greases have higher melting point (dropping

point) than calcium-based greases but are not resistant to the action of water. Lithium

based-based grease has a dropping point at 190 °C to 220 °C (350 °F to 400 °F).

However the maximum usable temperature for Lithium-based grease is 120 °C.

Grease used for axles are composed of a compound of fatty oils to which tar, graphite, or

mica is added to increase the durability of the grease and give it a better surface. [10]

2.3.3Additives

Teflon is added to some grease to improve their lubricating properties. Gear greases

consist of rosin oil, thickened with lime and mixed with mineral oil, with some

percentage of water. Special-purpose greases contain glycerol and sorbitan esters.. They


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are used, for example, in low-temperature conditions. Some grease are labeled "EP",

which indicates "extreme pressure".

Under high pressure or shock loading, normal grease can be compressed to the extent that

the greased parts come into physical contact, causing friction and wear. EP grease

contains solid lubricants, usually graphite and/or molybdenum disulfide, to provide

protection under heavy loadings. The solid lubricants bond to the surface of the metal,

and prevent metal-to-metal contact and the resulting friction and wear when the lubricant

film gets too thin. [11]

2.3.4 Other greases

Other types of lubricating material that are soft solids or high viscosity liquids at room

temperature are often called grease, though they may not exhibit the shear-thinning

properties typical of the oil/soap grease.

2.3.5Viscosity of hydraulic grease

The internal resistance to flow of a liquid is measured by a fluid’s viscosity. More

precisely absolute viscosity is defined in terms of the force between two parallel layers of

fluid for a certain slip velocity between them. This is represented by Newton’s equation

Very often a hydraulic fluid will be selected on the basis of its viscosity and the operating

temperature of the system.

A fluid will flow more easily the less viscous it is, since less energy is required to

overcome the internal frictional forces. Any saving in energy must be balanced against an

increase in leakage due to the lower fluid viscosity.

There are two measures of viscosity: absolute (also known as dynamic) and kinematics.

The S.I. unit for absolute viscosity is N s m-2 or Pa. The non-S.I. unit is the poise (P)

equivalent to 0.1 N s m-2 (not to be confused with the poiseuille (Pl), used in France, and


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equal to 10 poise) though the centipoises (cP) are more commonly used. In the hydraulics

industry kinematic viscosity is more frequently used, where:

The S.I. unit for kinematic viscosity is mm2s-1 which corresponds to the older but still

commonly used unit the centistoke (cSt).

Past measures of viscosity using arbitrary scales like Redwood No 1 seconds, Saybolt

Universal Seconds (SUS), or degrees Engler should no longer be used. These units have

been superseded by the empirical measures previously mentioned; conversion tables do

exist but are only true at a fixed temperature. [12]

Effect of temperature on viscosity

The temperature and viscosity of hydraulic oil are inversely related; as temperature

increases, viscosity decreases. In order to define the kinematic viscosity of oil, its

viscosity is quoted at a set temperature (40ƒC for the ISO standard) and the oil is given a

value according to the viscosity index (V.I.). For example oil quoted as conforming to

ISO 22 will have a viscosity of 22 mm2s-1/ cSt at 40ƒC. [13]

Effect of pressure on viscosity

Contrary to popular belief, varying pressure can lead to significant variations in viscosity.

In a closed flow circuit at a fixed temperature, a change in pressure of 40 MPa (400 bar)

can lead to a change of up to 8% in viscosity. However there are problems associated in

calculating this variation. [14]

Density and specific volume

The density of mineral oils is typically around 870 kg m-3 (in comparison synthetic oils

usually have a density of around 1200 kg m-3). The specific gravity, the ratio of the


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density of the fluid to the density of water, is a dimensionless quantity typically 0.87 for

mineral oils. [15]

2.4Lubrication

Lubrication is the process, or technique employed to reduce wear of one or both surfaces

in close proximity, and moving relative to each another, by interposing a substance called

lubricant between the surfaces to carry or to help carry the load (pressure generated)

between the opposing surfaces. The interposed lubricant film can be a solid, (eg graphite,

MoS2) a solid/liquid dispersion, a liquid, a liquid-liquid dispersion (greases) or

exceptionally a gas.

In the most common case the applied load is carried by pressure generated within the

fluid due to the frictional viscous resistance to motion of the lubricating fluid between the

surfaces.Lubrication can also describe the phenomenon when such reduction of wear

occurs without human intervention (aquaplaning on a road).

The science of friction, lubrication and wear is called tribology.

When we talk about (adequate) lubrication smooth continuous equipment operation is

assumed, with only mild wear, and without excessive stresses within the lubricated

conjunctions to cause seizure at the conjunction, or break of any part of the equipment,

and when such a catastrophic event does occur it means that the lubrication has broken

down. [16]

2.4.1The regimes of lubrication

When progressively increasing the load between the contacting surfaces three distinct

situations can be observed with respect to the mode of lubrication, which are called

regimes of lubrication:


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Fluid film lubrication is the lubrication regime in which through viscous forces

the load is fully supported by the lubricant within the space or gap between the

parts in motion relative to one another (the lubricated conjunction) and solid-solid

contact is avoided.

o Hydrostatic lubrication is a special case of fluid film lubrication in

which an external pressure is applied to keep the lubricant in the

conjunction, enabling it to support the external load.

o Hydrodynamic lubrication is also a special case of fluid film lubrication

which occurs when the lubricant is able to support the load without

external pressure, through hydrodynamic forces alone, which deform the

shape of the interposing lubricant film into a wedge shape and drags the

lubricant into the film, so that the externally applied load can be

supported.

Elastohydrodynamic lubrication: The opposing surfaces are separated but there

occurs some interaction between the raised solid features called asperities, and

there is an elastic deformation on the contacting surface enlarging the load

bearing area whereby the viscous resistance of the lubricant becomes capable of

supporting the load. [17]

Boundary lubrication (also called boundary film lubrication): The bodies come

into closer contact at their asperities; the heat developed by the local pressures

causes a condition which is called stick-slip and some asperities break off. At the

elevated temperature and pressure conditions chemically reactive constituents of

the lubricant react with the contact surface forming a highly resistant tenacious

layer, or film on the moving solid surfaces (boundary film) which is capable of

supporting the load and major wear or breakdown is avoided.


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Boundary lubrication is also defined as that regime in which the load is carried by

the surface asperities rather than by the lubricant.

Besides supporting the load the lubricant may have to perform other functions as well, for

instance it may have to cool the contact areas, or to removes wear products, and for

carrying out these functions the lubricant is constantly replaced from the contact areas

either by the relative movement (hydrodynamics) or by externally induced forces.

Lubrication is required for correct operation of mechanical systems engines, pumps,

cams, bearings, turbines, cutting tools etc where without lubrication the pressure between

the surfaces in close proximity would generate enough heat for rapid surface damage

which in a coarsened condition literally weld the surfaces together, causing seizures. [18]

2.5Valves

A valve is a device that regulates the flow of substances (gases, fluidized solids, slurries,

or liquids) by opening, closing, or partially obstructing various passageways. Valves are

technically pipe fittings. Valves are used in a variety of applications including industrial,

military, commercial, residential, and transportation. At SIMBI we have different types

of valves for different fluids but the most common valve is the gate valve. Some of the

valves are driven by pressure only; they are mainly used for safety purposes in bag filters.

I am going to use a valve for opening and closing the air supply to the pneumatic grease

pump.

2.5.1Application

Large varieties of valves are available and have many applications with sizes ranging

from small to large. The cost of valves ranges from very cheap simple disposable valves,

in some items to very expensive valves for specialized applications. Valves are almost as

ubiquitous as electrical switches. Often a valve is part of some object, the valve body and

the object made in one piece. Fluid systems in chemical and power plants and other

facilities have numerous valves to control fluid flow.


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2.6.2Valve parts

Body

The majority of the valve consists of the valve body, including most of the exterior. The

valve body is the vessel or casing that holds the fluid going through inside the valve.

Valve bodies are most commonly made of various metals or plastics, although valve

bodies fused with glass laboratory items in one piece are also made of glass.

Ports

The body consists of two or more openings, called ports from which movement occurs

from one opening to the next. These ports are controlled by the valve to control the fluid

flow. Valves with two or three ports are the most common, while valves consisting of

four or more ports are not as frequently used. Extra ports that are not needed can be

closed off by the valve. Manufacturing of valves often occurs with the intent that they

will be connected with another specific object. These objects can vary, but generally

these include some type of piping, tubing, or pump head. In some cases, a valve port is

immediately connected to a spray nozzle or container. To make a connection, valves are

commonly measured by the outer diameter the ports they connect to. For example, a 1-

inch valve is sized to connect to 1-inch outer diameter tubing.

Combined with a valve, ports have the ability to act as faucets, taps, or spigots, all while

one or more of its remaining ports are left unconnected. Most valves are built with some

means of connection at the ports. This includes threads, compression fittings, glue or

cement application (especially for plastic), flanges, or welding (for metals).

Discs and rotors

Inside the valve body, flow through the valve may be partly or fully blocked by an object

called a disc. Although valve discs of some kinds of valves are traditionally disc-shaped,

discs can come in various shapes. Although the valve body remains stationary within the

fluid system, the disc in the valve is movable so it can control flow. A round type of disc


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with fluid pathway(s) inside which can be rotated to direct flow between certain ports can

be called a rotor. Ball valves are valves which use spherical rotors, except for the interior

fluid passageways. Plug valves use cylindrically-shaped or conically-tapered rotors called

plugs. Other round shapes for rotors are possible too in rotor valves, as long as the rotor

can be turned inside the valve body. However not all round or spherical discs are rotors;

for example, a ball check valve uses the ball to block reverse flow, but is not a rotor

because operating the valve does not involve rotation of the ball.

Seat

The valve seat is the interior surface in the body which contacts or could contact the disc

to form a seal which should be leak-tight, particularly when the valve is shut (closed). If

the disc moves linearly as the valve is controlled, the disc comes into contact with the

seat when the valve is shut. When the valve has a rotor, the seat is always in contact with

the rotor, but the surface area of contact on the rotor changes as the rotor is turned. If the

disc swings on a hinge, as in a swing check valve, it contacts the seat to shut the valve

and stop flow. In all the above cases, the seat remains stationary while the disc or rotor

moves. The body and the seat could both come in one piece of solid material, or the seat

could be a separate piece attached or fixed to the inside of the valve body, depending on

the valve design.

Stem

The stem is a rod or similar piece spanning the inside and the outside of the valve,

transmitting motion to control the internal disc or rotor from outside the valve. Inside the

valve, the rod is joined to or contacts the disc/rotor. Outside the valve the stem is attached

to a handle or another controlling device. Between inside and outside, the stem typically

goes through a valve bonnet if there is one. In some cases, the stem and the disc can be

combined in one piece, or the stem and the handle are combined in one piece.

The motion transmitted by the stem can be a linear push or pull motion, a rotating

motion, or some combination of these. A valve with a rotor would be controlled by

turning the stem. The valve and stem can be threaded such that the stem can be screwed


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into or out of the valve by turning it in one direction or the other, thus moving the disc

back or forth inside the body. Packing is often used between the stem and the bonnet to

seal fluid inside the valve in spite of turning of the stem. Some valves have no external

control and do not need a stem; for example, most check valves. Check valves are valves

which allow flow in one direction, but block flow in the opposite direction. Some refer to

them as one-way valves.

Valves whose disc is between the seat and the stem and where the stem moves in a

direction into the valve to shut it are normally-seated (also called 'front seated'). Valves

whose seat is between the disc and the stem and where the stem moves in a direction out

of the valve to shut it are reverse-seated (also called 'back seated'). These terms do not

apply to valves with no stem or to valves using rotors.

Bonnet

A bonnet basically acts as a cover on the valve body. It is commonly semi-permanently

screwed into the valve body. During manufacture of the valve, the internal parts were put

into the body and then the bonnet was attached to hold everything together inside. To

access internal parts of a valve, a user would take off the bonnet, usually for maintenance.

Many valves do not have bonnets; for example, plug valves usually do not have bonnets.

Spring

Many valves have a spring for spring-loading, to normally shift the disc into some

position by default but allow control to reposition the disc. Relief valves commonly use a

spring to keep the valve shut, but allow excessive pressure to force the valve open against

the spring-loading,

Valve balls

A valve ball is also used for severe duty, high pressure, high tolerance applications. They

are typically made of stainless steel, titanium, Stellite, Hastelloy, brass, and nickel. They

can also be made of different types of plastic, such as ABS, PVC, PP or PVDF.


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Valve operating positions

Valve positions are operating conditions determined by the position the disc or rotor in

the valve. Some valves are made to be operated in a gradual change between two or more

positions. [19]

CHAPTER 3

Conceptual Designs

3.1 Introduction

This chapter only focuses on the conceptual designs that can be implemented on

this automatic lubrication system. However I had restricted my conceptual

designs to at least 3 so as to reduce the size of the write up at the same time

clearly explaining my chosen possible solutions. I had included drawings of

which I used mainly 2 software packages, AUTOCAD2004 and CADKEY2004,

which were readily available at the company and nearby resource centers (local

library).

3.2 The Design Matrix Table

The use of a design matrix table enables the designer to have several choices and not to

be locked in one area as he tries to solve the problem at hand, this is the concept that I

learn from the late Mr. T Zhuga during our Engineering Design and Innovation Course.

This table clearly shows the minimum number of solutions that I can implement to solve

the problem at hand, however the information in bold constitute the chosen solution.


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Having in mind the fact that I had to use available resources my design strategies mainly

focused on how to implement them by correctly interfacing the available instruments and

softwares.

CONCEPTUAL DESIGNS AS AN OVERVIEW

CONTROLER Programmable logic controller*

PID

Intel 8085 microprocessor

VALVE ACTUATOR Butterfly valve

Solenoid valve*

PUMP TYPE Electrical pump

Pneumatic pump*

Manual hand pump

PRESSURE REGULATOR One directional pressure regulator*

INTELLIGENCE Model based adaptive control system

Model free adaptive control system*

Fuzzy logic controllers

SCADA TYPE Wonderware

Cimplicity*

Genesis

LADDER PROGRAMME TYPE Versapro*

LUBRICANT Universal grease*

EP2

PRESSURE TRANSMITTER Honeywell ST300


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A market research was carried out so as to come up with the conceptual designs above,

however all the conceptual designs were detailed in this Chapter so that one will

understand the main reason why I chose a particular instrument or software.

The information in Chapter 4 will also be helpful during installation and commissioning

of this Project as detailed information is provided and specifications clearly analysed

from all perspectives of Engineering.

CHAPTER 4

ANALYSIS OF CHOSEN SOLUTIONS

4.1The Intelligence

Model-free adaptive (MFA) control system

My control system has a single input and a single output (SISO) so I decided to choose

MFA because it requires no model and has SISO characteristics.

Features

o No precise quantitative knowledge of the process available.

o No process identification mechanism or identifier is included in the

system

o No controller design is require but to use the available PLC.

o No complicated turning of controller parameter is required.

o Stability analysis criteria are available to guarantee the open loop

system stability.

Overview


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It consists of a single loop control system that includes a SISO process, a SISO MFA

controller (PLC) and a feedback loop.

Control objective

The control objective of the controller is to produce an output u(t) to force the process

variable y(t) to track the given trajectory of its set point r(t) under variations of set point

disturbances and process dynamics.

The function of MFA controller is to minimize the error e(t) in an online function. The

minimization of e (t) is achieved by:

The regulatory control capability of the MFA controller.

The adjustment of the MFA controller weighing factors that allow the controller

to deal with the process dynamic changes, disturbances, and other uncertainties.

No model error em(t) needs to be minimized and only the error e(t) between set point r(t)

or PV and process variable y(t) needs to be minimized. [20]

SISO means Single input, Single Output


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SCADA as applied to lubrication system

SCADA –Supervisory Control and Data Acquisition the terms refer to large scale

distributed measurement and control system. The bulk of the site control is actually

performed automatically by a Remote Terminal Unit or PLC as for SIMBI most of the

control functions are restricted to basic plant override or supervisory level capability. It

includes all HMI controllers, I/O devices; networks and software (Cimplicity as for

SIMBI). It implements a distributed database, which contains data elements called points.

Hard point representative of actual O&I connected to the system. Soft point result of

mathematical \operations applied to hard and soft points. [21]

The diagram below shows how the SCADA Software interface is like. The main reasons

why I chose this SCADA package are that:

It uses pictures which look almost like the actual instrument or machine in the

field and it is readily available at the company as compared to the other packages.


26

Automation being carried out by Engineers, Mr. I. Muchimwe and Mr. Talon

Garikayi

4.2Automation as applied to lubrication system

Is the automatic processes done by machines with minimum to no human interference.

The Fig above clearly shows how I will be able to control the whole Lubrication System

from the Main control room. They will be two PCs, one for the Engineer on my Left and

the Station manager PC that carries the SCADA software.

As the name indicates, it is not a full control system, but rather focuses on the supervisory

level. As such it is a purely software package that is positioned on top of hardware to

which it is interfaced, via PLCs. The system collects data from various sensors in the

plant and then sends this data to a central computer that then manages and controls the

data. The plant control logic resides in the PLC and it does all the logic decisions. [22]


27

Roles

Aid humans

Increase production

Control management

Increase precision.

Characteristics

System must be safe

System must be comprehensive

System must have minimum human interference.

Improve production, easy maintenance and cost effective.

Supervisory Control Architecture

Control engineering is the engineering discipline that focuses on the modeling of a

diverse range of dynamic systems (e.g. mechanical systems) and the design of controllers


28

HUMANINTERVENTION

SENSOR

SYSTEMSUPERVISORYCONTROLCOMPUTER

CONTROL

DISPLAY

INTERFACE

http://en.wikipedia.org/wiki/Controller_(control_theory)

http://en.wikipedia.org/wiki/Systems

http://en.wikipedia.org/wiki/Mechanics

http://en.wikipedia.org/wiki/Dynamic_system

http://en.wikipedia.org/wiki/Mathematical_model

http://en.wikipedia.org/wiki/Discipline

that will cause these systems to behave in the desired manner. Although such controllers

need not be electrical many are and hence control engineering is often viewed as a

subfield of electrical engineering.

Electrical circuits, digital signal processors and microcontrollers can all be used to

implement Control systems. Control engineering has a wide range of applications from

the flight and propulsion systems of commercial airliners to the production of sponge iron

at SIMBI.

Control engineers often utilize feedback when designing control systems. For example, in

temperature is continuously monitored and fed back to the system which adjusts the

motor's speed accordingly. Where there is regular feedback, control theory can be used to

determine how the system responds to such feedback. In practically all such systems

stability is important and control theory can help ensure stability is achieved.

Although feedback is an important aspect of control engineering, control engineers may

also work on the control of systems without feedback. This is known as open loop. A

classic example of open loop control is the opening and closing of my solenoid valve

given a signal from the.

Other functions of SCADA are:

To generate trends and reports of the plant parameters.

To generate alarms.

To have graphical views of the whole plant.

To provide troubleshooting guides.

So many SCADA packages are currently in use throughout the world. Some of the most

common ones are:

- Wonder ware

- Cites

- Genesis


29

http://en.wikipedia.org/wiki/Control_theory

http://en.wikipedia.org/wiki/BIBO_stability

http://en.wikipedia.org/wiki/Control_theory

http://en.wikipedia.org/wiki/Speed

http://en.wikipedia.org/wiki/Internal_combustion_engine

http://en.wikipedia.org/wiki/Control_system

http://en.wikipedia.org/wiki/Feedback

http://en.wikipedia.org/wiki/Airliner

http://en.wikipedia.org/wiki/Control_system

http://en.wikipedia.org/wiki/Microcontroller

http://en.wikipedia.org/wiki/Digital_signal_processor

http://en.wikipedia.org/wiki/Electrical_circuit

- RS View

- Cimplicity

At SIMBI, we use CIMPLICITY SCADA. It is important to note that SCADA is not a

controller but simply interfacing software between the controller and the operator’s panel,

the computer. [23]

4.4 The Human Machine Interface (HMI)

A SCADA system includes a user interface usually controls where the individual can

interface with the SCADA system. The SCADA system communicates with PLCs

throughout the system network and processes information that is easily disseminated by

HMI

At SIMBI we use two computers the Engineering PC and the Station manager PC for our

SCADA system. The only way one can communicate well with my design is through the

computer using the SCADA, this actually made my design user friendly and increased its

value as a fully automated project design hence easy to implement. [24]

The Human Machine Interface Characteristics


30

CHAPTER 5

The Controller

5.0 The PLC (VersaMax Model)

Inside the PLC panel (the selected project controller)

5.1 Introduction

I was trained on how to do fault finding and appreciate the need for a controller in the

processing industry so I compiled the information in this chapter with great caution since

any wrong information could lead to a disastrous future in the control engineering field.

Most of the literature was researched after practicals with the Instruments engineer. This

was one of the most challenging topics of my attachment since it strongly requires good


31

background of control engineering. Emphasis was on understanding the principle factors

under industrial measurement and control.

5.2 The Details of the Controller

The GE Fanuc* PLC system consist of Ethernet based control processing unit and total

programming for monitoring and controlling the various equipment pertaining to the

plant.

A PLC is a microcomputer based controller that uses stored instructions in programmable

memory to implement logic, sequencing, timing, counting and arithmetic functions

through digital or analogue I/O module for controlling machines and processes. The

microprocessor is used for automatic distribution of real world process but designed for

an extended temperature ranges dirty or dusty conditions. It is immune to electrical noise,

mechanically more rugged and resistant to vibrations.

Processor

It is the CPU of the programmable controller. It executes the various logic and

sequencing functions by operating on the PLC inputs to determine the appropriate output

signals. It consists of one or more microprocessors designed to facilitate I/O

transmissions. The GE Fanuc* PLC like all PLCs, it has inbuilt facilities like timers

counters, PID loops and parameters like memory bits registers, global bits, temporary

bits, and system bits that can be configured as per plant requirements through

programming software for the better monitoring and control of the plant.

Memory unit

It is connected to the CPU; it contains the programs of logic sequencing and I/O

operations. It also holds data files associated with these programs including I/O status

bits, counter and timer constants, other variables and parameter values. This memory unit

is referred to as the user or application memory because it s contents are entered by the


32

user. In addition the processor has a system that directs the execution of the control

program and coordinates I/O operations. The contents of the system memory are entered

by the manufacturer and cannot be accessed or altered by the user.

Power supply

A power supply of typically 120VAC is used to drive the PLC some 230VAC .It converts

AC to DC of 5V. It often includes a battery back up that switches on automatically in he

event of an external power source failure. At SIMBI a UPS is connected in series and

there is a 230AC transformer of equal voltage on Primary and Secondary winding

responsible for smoothening the 230ACV. A number of breakers are installed in the PLC

panel for different inputs. These are:

Transformer

PC

Digital output signals

Digital input signals

Analogue signals

NB: swichedmode power supply units are the ones in use.

Input/ Output Module

Provides the connectors to the backplane and process that is to be controlled. Inputs to the

controllers are signals from he sensors and other ON/OFF devices. Outputs from the

controller are ON/OFF signals to operate actuators and other devices required to activate.

Many PLCs are capable of accepting continuous signals from analogue sensors and

operate signals suitable for actuators.

Programming device

The PLC is programmed by means of a special programming device. It is detachable

from he PLC cabinet so that it can be shared among the controllers. A PC (as for SIMBI)


33

can be used, but usually remain connected to serve a process monitoring or supervision

functions related to the process.

Expansion transmitter modules

These modules are responsible for communication between the processor and the

input/output modules. There is a main ETM and is the one responsible for direct

communication and the rest of the ERMs behave as parasites.

General Structure of a PLC consists of the

CPU,

Output and Input modules,

Power supply

Detachable programming device

Expansion transmitter modules


34

5.3 Schematic representation o f the PLC

5.4 The Control Signals

Digital Inputs

These are real discrete inputs from the field that will include limit switches for the stutus

of my solenoid valve , level switches for the level of my lubricant , flow switches, push

buttons for the condition of the pneumatic pump ,contactors, overload relays.

Digital input modules are configured to accept these inputs, which are connected to the

same power supply from the CPU.


35

Mains supply

Power Supply

Analogy Input and Output Modules

Detachable Programming device

Digital Input and Output Modules

ProcessorCPU

Memory unit

The switching mode for digital inputs can either be source mode or sink mode and are

activated on by either a 24 VDC, 110 VAC at 220VAC. The most common are the source

mode, which has a switching signal at the (+) positive. For sink mode, the switching

mode is (-) negative; therefore, the PLC will sink (switching a mental OV). At SIMBI

there are 32 input modules with a 24 VDC switching voltage (source mode).

Digital Output

Give out a voltage usually 24 VDC to field devices such as relays, contractors, transistors

depending on the type of PLC. Usually the output is a low current which is used to switch

a higher current or

Analog Inputs

Receives signals from real world analog signals which will include the ST300 pressure

transmitters. Most common type of inputs are: 0 – 20mA; 0,-5V; 0,-10V; 1 – 5V, 1 – 10V

and 4 – 20mA. At SIMBI, the most widely used analog input is the 4 – 20 mA.


36

24VDC

12345 INPUT MODULE

32

Schematic representation of Analog Inputs

Input module/card

Source voltage

NB: The wiring of digital inputs is different from that of analogue inputs. If the 4 – 20

mA is coming from a transmitter, a power supply, in our case, of 24VDC is required.

Analog Output Signals

Gives output commands to field devices such as control valves, pneumatic pump and

solenoid valve. The signal current operates the current to pneumatic converter.

Address: - % AQ 0001

To actuator

To actuator


37

24VDC

TRANSMITER

+-CH1

+- CH2

+- CH3

+- CHn

SENSOR

+ CH1 - + CH2 - + CH3-

CHAPTER 6

The Main PLC Components

6.1 The CPU (Details)

Introduction

The Output and Input modules are fitted on the female connectors to enable

communication with the CPU, which is also placed on the back plane. The power supply

of the back plane is to supply some modules with power.

NB: Not all output and input modules get their supply from the power supply in the PLC,

but some input/output modules are supplied from the back plane.

Structure of a Module

Each back plane accommodates a specific number of modules and if the required

modules in a plant exceed the maximum number accommodated by a back plane, there is

need for an Expansion Transmitter Module which will enable the CPU on a certain back

plane to communicate with Input and Output Module in another back plane.

NB: All other modules which are connected on a different back plane from the one with

the CPU need an Expansion Receiver Module (ERM) which receives instructions or

signals from the Expansion Module (ETM).

All Analog Output Modules are powered from the back plane with a 5V supply. Digital

Output sends output to the relays, which will enable switching on of high currents. There


38

are two types of relays in use, NO (normally open) and NC (normally closed) Each relay

has one digital output from the PLC.

Back Plane

This is the plane where digital/analog modules are mounted. At SIMBI, the back plane

can support up to 9 modules. Some of the output modules take their supply voltage from

the back plane, however at SIMBI most of the output modules are not supplied from the

back plane.

Expansion Transmitter Module (MDL 650)

It is the main transmitter from the CPU to the output modules. All other ERMs depend on

the ETMs thus; they behave in a parasite manner. For every backplane, we have the

ERM. In addition, when changing modules one should take note of the codes.

Digital outputs and inputs can be slotted on the same back plane but it is wise for

uniformity to separate them that is using different back planes.

At SIMBI, there are 7 digital output modules which translate to 7 x 32 output signals

from the PLC. In addition, there are also 17 digital input modules, which translate to 17 x

32 input signals.

NB: Analog Output Modules uses 24VDC from SMPS and Input Modules use 5VDC

from the back plane.

6.2 Hardware Configuration

When assembling a PLC you carry out hardware configuration first ie.

Choosing the correct type of CPU

Choosing the correct digital input card (32 port)


39

Selecting the type of mode (SIMBI uses source mode)

Correctly, use slot number and rack number for the PLC to correctly identify the

Input/Output signals.

Relays

SIMBI uses 24VDC relays and they are high current rating relays. These are of two

types, Normally Open (NO) and Normally Closed (NC). Each digital output uses one

relay .

LED

The LED ON, on the Modules only signal whether the signal from the instrument is

reaching the PLC. These LEDs are helpful during trouble shooting of an instrument.

Digital outputs have only 2 LEDs for power supply.

Terminal Block Side (TBS)

The blocks are used to connect the cables from the field to the PLC. This reduces the

number of cables into the PLC panel and provides SMART installation. Terminal blocks

on the terminal side also help a lot during troubleshooting. The cables are given addresses

for easy identification e.g.

Analog Outputs AQ0001 (Blue Cable)

Analog Inputs AI 0001

Digital Outputs R0001 (Blue cable)

Digital Q000I(Yellow cable)

NB: Take note that after expansion of the plant, some of the cables are not labeled and

the terminal side has changed a lot and is not yet updated.


40

CHAPTER 7

The Pneumatic Pump and the Pressure Regulator

7.1 High Pressure (Grease Pump) Selection Guide

Each application varies and should be carefully considered for special conditions that

may require a pump selection other than the standard recommendations listed. These

conditions include, but are not limited to:

Viscosity of product pumped

Ambient temperature conditions

Simultaneous operation of several dispensing outlets

Dispensing volume requirements ,also when measuring total pump distance, the

hose length of dispensing reels should be included in total distance.

Pneumatic T-junction

A T-junction is a very small piece that allows three pieces of tubing to connect into one

junction, essentially splitting (or joining) airflow from two hoses into one. These only

allow 1:2 branching, but by combining T-junctions, any number of branches can be

achieved (i.e.: one tube can branch into three by using two T-junctions).

Pneumatic Tubing

Tubing is simply the means by which air power is transferred through the circuit. Tubing

can connect to a switch, air tank, T-junction, cylinder, pump, distribution block, or flex-

hose.Flex-hoses aren't actually considered pneumatic pieces; they were designed as part

of the Technic system for a different purpose, but I have discovered that pneumatic

tubing actually fits over flex hoses pretty well; so many people use them as tubing

extenders whenever they are needed. Flex hoses are more rigid than tubing. Most


41

pneumatic tubing almost always comes with sets in an uncut form, and are required to be

cut into smaller pieces using scissors.

7.2 The Pressure Regulator

The first pressure regulator has to allow a constant air pressure supply of 140Kpa (21psi)

to be used as an input to the Current-to-Pneumatic converter.

The second pressure regulator has to allow a constant air pressure supply of 140Kpa

(21psi) to be used as an input to the Valve Positioner.

The pressure regulator is a normally open valve and is installed at the START of a system

or before pressure sensitive equipment to regulate or reduce undesirable higher upstream

pressure. Too often, a pressure regulator is installed. In this case, the pressure regulator

will simply stay wide open and just send liquid straight into the tank without maintaining

upstream pressure...just a very expensive fitting.

Where an obstruction will benefit everything after the valve, a pressure regulator should

be used so that not all the equipment after it will have excessive pressure. Used where it

should be that is at the beginning of a process, the pressure regulator will ensure safe

downstream pressure. The combination of a pressure regulator at the beginning of a

system, and a backpressure regulator at the end of a system, will ensure balanced pressure

throughout the system. This is a simplification, of course, and the specifics within any

given system can vary greatly.

7.3 Calculations.

Using the equation of continuity

Assumption: The flow rate at any point of the system obeys this equation


42

By varying the area of the opening at the outlet of the regulator we can regulate the outlet

pressure.

Applying Bernoulli Principle, under steady state flow, well developed flow conditions the

total energy of a unit volume of material must be constant at every part of the system.

By increasing we decrease and increase the pressure thereby regulating pressure.

7.4 Justification of chosen solution

Improved Control

You can rely on this real-time information to make sound process management

decisions. By analyzing pressure dynamics through SCADA Software, you can

identify control areas needing improvement and maintain a high level of system

performance.

Environmental Protection

You can avoid additional field wiring by connecting a leak detector or limit

switch to the auxiliary terminals of the solenoid valve, in this way, the instrument

will issue an alert if limits are exceeded.


43

Enhanced Safety

You can check the pressure regulator and keep the process running smoothly and

safely from a remote location. Access is possible during maintainence since one

can easily isolate the regulator using the isolating valves installed.

Hardware Savings

Pressure regulator, when used in an integrated system, allow you to realize

significant hardware and installation cost savings by replacing other devices in the

process loop, such as suppressors and gauges.

Easy Maintenance

Solenoid valves are modular in design. The module base can be removed from the

instrument housing without disconnecting the field wiring, pneumatic connections

or stem linkages. This module contains the critical sub-modules so component

removal is quick and simple.


44

CHAPTER 8

8.0 The Pressure Transmitter

Introduction

This is an optional instrument that can only be used if there are enough resources at the

company. “We can not promise you that we need to monitor the pressure of the

pneumatic grease pump or the solenoid valve since we can find the types that can use line

pressure.”[9] Said Mr. I. Muchimwe (The instruments Engineer). However I do believe

this is a necessary instrument considering the fact that our plant is already highly

automated and we already have some pressure transmitters in stock.

8.1 Honeywell ST300 SMART Pressure Transmitter

Functional Principle

The transmitter is ready for operation immediately after installation. The settable

measuring span corresponds to the specification on the rating plate. If customized setting

is made at the factor, the start of scale are specified o the measuring pate .If necessary,

the parameters can also be changed during commissioning by simple operating

procedures.

Design

The device consists of different components depending on what the

customer has specified in the order. The possible variants will be listed in

the operating manual.

The rating plate with the order number is on the side of the housing. One

can determine the optional constructional details and the possible


45

measuring range (physical properties of the built –in sensor element) with

the specified number and specifications.

Advantages

A single technician can test the entire signal loop from a central location.

Significant reduction in down time.

Time savings during start up and maintenance

Disadvantages


46

It is mainly suitable for absolute pressure measurements yet we want to measure

the differential pressure.

I am not going to implement this type of pressure transmitter because it cannot

withstand the high temperatures experienced at the kiln section and I have to

implement a differential pressure transmitter.

8.2 Installation

We must not overlook the possibility of condensate freezing in impulse lines to

transmitters measuring gas pressure. Although these components could be heated similar

to water and steam applications, the simplest and best approach is to install transmitters

so that they are self draining. This means that the impulse lines are connected to the

lowest point in the transmitter meter body and the piping is sloped downward at least one

inch per foot. If the transmitter is located below the process taps, piping must still run

downward from the transmitter to the point and then to the process as shown below:

When the transmitter is in its DE mode, the process variable is available for monitoring

and control purposes; and the meter body temperature is also available as a secondary

variable for monitoring purposes only.


47

8.3 Valve orientation


48

8.4 Pipe installation for Differential Pressure Transmitter


49

8.5 Justification of Chosen Solution

Improved Control




performance.

Environmental Protection

You can avoid additional field wiring by connecting a leak detector or limit

switch to the auxiliary terminals of the pressure transmitter, in this way, the

instrument will issue an alert if limits are exceeded.

Enhanced Safety

You can check instrument and valve operation and keep the process running

smoothly and safely from a remote location. Access is possible at a field junction

box, marshalling panel, or within the safety of the control room using a system

workstation. Your exposure to hazardous environments is minimized and you can

avoid having to access hard-to-reach high temperature locations.

Hardware Savings

Pressure Transmitter when used in an integrated system, allow you to realize


process loop, such as pressure gauges.

Easy Maintenance

Pressure Transmitters are modular in design. The module base can be removed

from the instrument housing without disconnecting the field wiring, pneumatic

connections or stem linkages. This module contains the critical sub-modules so

component removal is quick and simple.


50

8.6 The Air Compressor

At SIMBI, we use a Centrifugal air compressor -a vane rotating disk or impeller in a

shaped housing forces the gas to the rim of impeller increasing the velocity of the gas.

A diffuser (divergent duct) section converts the velocity energy to pressure energy. These

are used for continuous, heavy industrial uses and are usually stationary.

Their application can be from 100 hp (75 kW) to thousands of horsepower. With multiple

staging, they can achieve extremely high output pressures greater than 10,000 lbf/in² (69

MPa). Fluid-handling devices are not concerned with the modulation of power, but only

with the movement of fluid. Choosing a fluid-handling valve used to be easy, because

each one had its own area of utility.

For on off, full, or no-flow requirements, ball and gate valves were favored; where tight

shut-off was not required, butterfly and slide valves were used.

As a result, beliefs were formed which may inhibit the selection of the best valve for my

design.

8.7 The Lubricant Tank

This is the container where the pneumatic pump shall be mounted. This tank also serves

the purpose of storage of the lubricant during lubrication. A number of factors were

considered during the selection of the tank.

Pump distance that is the distance to be traveled by the lubricant before it reaches

its intended point of lubrication.

Number of outlets.

Maximum pressure the pneumatic pump will be exerting.

Tubing pipe size.


51

The Lubricant tank diagram


52

CHAPTER 9

The Control System

9.0 Control Philosophy

As an abstract, the plant has been divided into four major segments.

i) Kiln and Cooler Section

ii) Waste Gas Section

iii) Product Separation Section

iv) Raw material handling section

The corresponding signal from every individual section has been connected to the PLC

system through the corresponding Input and Output modules. The CPU is continuously

processing the data as per the program logic and communicating the SCADA – Graphical

interface terminals for equipment status, monitoring and control.

The proposed PLC is user friendly and during the operation, in case of any fault due to

malfunction of any input address, the same can be reset by assigning some other address

from the spare block for ensuring the smooth functioning of the plant.

The necessary interlocks have been incorporated for every equipment to safe guard from

any eventualities and ensuring the smooth operation of the plant.

The system is designed to operate in 3 modes mainly:

i) Manual

ii) Auto


53

iii) DE INT

9.1Manual Mode

In this mode, the system can be started / stopped through SCADA i.e. from computer.

Here we can start all drives as well as conveyers by clicking the respective icons. All

interlocks are applicable in this mode.

9.2 Auto Mode

Generally, the system is operated in this mode. Here the system is designed in such a way

that the entire plant can be started with one click or individual major sections can be

started one by one.

9.3 DE INT Mode

In this mode, all the drives can be started/stopped independently irrespective of the

interlocks and is generally used for maintenance purposes.

The selection of the control of the plant is achieved by selecting LOCAL/REMOTE

positions in the MCC. To operate the plant in Auto mode all the selector switches should

be in REMOTE mode. When the system is in Auto mode, if any of the selector switches

in a particular group changes to LOCAL mode, then the whole group trips along with

down stream groups.

NB; In case it is necessary to keep one or few drives out of the total sequence of

operation, this is achieved by putting them in DE INT mode.


54

CHAPTER 10

Programming the Controller

10.0 PLC Programming

Introduction

A program is a set of instructions to execute a certain function. The instructions to be

performed during each scan are coded and inserted into memory with the programs.

Programming is carried out using a programming unit, which provides an interface

between the PLC and the user during program development, start up and trouble

shooting.

What makes a PLC special? PLC's are used to automate machinery in assembly lines.

For our (plant) project, we use the computer link feature that allows a PLC to take

commands and communicate with a host computer. If something goes wrong with the

computer link, the PLC still functions and protecting valuable equipment. This PLC and

most others use a language called relay ladder logic programming. Normally in a

programming language things happen in order.

The command or line of code on top is executed before the command on the bottom until

you hit the end of a loop. This is not so in ladder logic. Everything happens at the same

time.

So what is ladder logic programming really like? Ladder logic programming looks, well,

like a ladder. It's more like a flow chart than a program. There are two vertical lines


55

coming down the programming environment, one on the left and one on the right. Then,

you have rungs of conditionals on the left that lead to outputs on the right.

The things you will probably use the most writing Ladder Logic are the relay conditionals

--| |-- ---|/|--- and the output coils --- ( ) ---. These three things basically make up a kind of

IF THEN statement.

10.1 Ladder logic Programming Software

Ladder logic Programming Software is a method of drawing electrical logic schematics.

It is now a graphical language very popular for programming PLCs. It was originally

invented to describe logic made from relays. The name is based on the observation that

programs in this language resemble ladders, with two vertical "rails" and a series of

horizontal "rungs" between them.

A program in ladder logic, also called a ladder diagram, is similar to a schematic for a

set of relay circuits. An argument that aided the initial adoption of ladder logic was that a

wide variety of engineers and technicians would be able to understand and use it without

much additional training, because of the resemblance to familiar hardware systems.

(This argument has become less relevant given that most ladder logic programmers have

a software background in more conventional programming language and in practice

implementations of ladder logic have characteristics — such as sequential execution and

support for control flow features — that make the analogy to hardware somewhat

imprecise.)

Ladder logic is widely used to program PLCs, where sequential control of a process or

manufacturing operation is required. Ladder logic is useful for simple but critical control

systems, or for reworking old hardwired relay circuits. As programmable logic


56

controllers became more sophisticated it has also been used in very complex automation

systems.

Manufacturers of programmable logic controllers generally also provide associated

ladder logic programming systems.

Typically, the ladder logic languages from two manufacturers will not be completely

compatible; ladder logic is better thought of as a set of closely related programming

languages rather than one language (the IE 61131-3 standard has helped to reduce

unnecessary differences, but translating programs between systems still requires

significant work).

Even different models of programmable controller within the same family may have

different ladder notation such that programs cannot be seamlessly interchanged between

models.

Ladder logic can be thought of as a rule-based language, rather than a procedural

language. A "rung" in the ladder represents a rule. When implemented with relays and

other electromechanical devices, the various rules "execute" simultaneously and

immediately.

When implemented in a programmable logic controller, the rules are typically executed

sequentially by software, in a loop. By executing the loop fast enough, typically many

times per second, the effect of simultaneous and immediate execution is obtained. In this

way it is similar to other rule-based languages, like spreadsheets or SQL. However,

proper use of programmable controllers requires understanding the limitations of the

execution order of rungs.

Hence a program is a set of instructions to execute a certain function. The instructions to

be performed during each scan are coded and inserted into memory with the programs.


57

Programming is carried out using a programming unit, which provides an interface

between the PLC and the user during program development, start up and trouble

shooting.

The flowchart representing the execution of tasks by the controller (PLC)

NO

YES

NO

YES


58

START

SWITCH ON THE POWER SUPPLY TO THE SOLENOID VALVE

CHECK THE VOLUME OF THE LUBRICANT IN THE TANK

IS THE KILN AND COOLER ROTATING

IS THE AIR COMPRESSOR

ON

ENERGIZE THE SOLENOID VALVE

PNEUMATIC PUMPING OPERATIONAL

DE-ENERGIZE THE SOLENOID VALVE

FIN ISH


59


60

RUN MODE

LOGIC SOLUTION

I/OENABLED

I/OENABL

ED

OUTPUT SCAN

PROGRAMMER COMMUNICATIONS

SYSTEM COMMUNICATIONS

APPLICATION PROGRAM

CHECK SUM CALCULATIONS, VERIFICATION AND PROGRAMME CONFIGURED

INPUT SCAN

START OF SWEEPHOUSEKEEPING HOUSEKEEPING

DATA INPUT

PROGRAMMEEXECUTION

DATA OUTPUT

PROGRAMMERSERVICE

SYSTEMCOMMUNICATION

DIAGNOSIS

fig


61

The Control and Power wiring diagram for the Lubrication System


62

fig


63

Ladder Diagram for the Automated Lubrication System

10.2 Schematic representation of the Control System components

Fig 13


64

COMPRESSOR PRESSUREREGULATOR

FILTER

SOLENOID VALVE

PLC “CONTROLLER”

SCADA “STATION MANAGER”

PNEUMATIC PUMP

ROTAY KILN AND COOLER

LUBRICANT

CHAPTER 11

11.0 The Actuator

11.1The Valve

Introduction

The valve will be used to allow the compressed air to switch on the Pneumatic pump; this

will be done on well calculated intervals.

11.2The butterfly valve-not a chosen solution

The Butterfly valve (actuator) will receive a pneumatic signal of 80 psi from the valve

positioner. I decided to use the type of butterfly valve described below because of its

ability to withstand vibrations and high temperatures experienced at the plant.

Triad offers direct mount rack and pinion pneumatic actuators that have double travel

stops insuring precise seating of disc. These actuators are available in both double acting

and spring return versions.

The actuator is corrosion resistant inside and out. Available accessories include modular

mount positioners, pilot solenoid valves and limit switch assemblies.

Were once used for low-pressure service where complete shutoff was not necessary, and

they were not used to modulate flow. Butterfly valves had the advantage of small size,

lightweight, simple design, and low-pressure drop. They also required only a one-quarter

turn to change from closed to the fully open position.


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Today, butterfly valves retain their traditional virtues. But capabilities have been greatly

extended by offset discs and polymeric seals. These and other design innovations have

enabled butterfly valves to be used for throttling, tight sealing, and withstanding

pressures as high as 1,200 psi while retaining many traditional advantages.

A modern butterfly valve may include a pressure-tight resilient seat and an angularly

offset disc. Other butterfly valve designs use a hard seat and an O-ring or piston ring

around the disk to seal. Butterfly valves range in size from small to enormous, and are

well suited for large flows of gases, liquids, or slurries.

The system offers long cycle life and a corrosion-free mating surface. The valve has a

ductile iron disc, resilient seat, and self-lubricating sleeve bearings, self-adjusting /wear

compensating shaft seal, and taper pins that lock the disc to the shaft to prevent leakage.

The plant uses mostly wholly mechanical butterfly valves, situated on a rugged

environment with great vibrations hence their principle of operation involves the use of

dents and a pointer. Statistics reveal that most workers do not correctly set the valves

giving wrong feedback information to the plant operator.

Some employees do not understand the importance and usually ignore to check the status

of the valves leading to poor production so I decided not to use a gate valve but managed

to choose a solenoid valve.

Reasons for rejection as a choice

This type of valve is wholly mechanical therefore it will be impossible to activate it from

the Central Control room so that the control system becomes automatic. I however intent

to use it as an in-line valve that can work if my regulator fails to operate during


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production process.


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Fig 14 SAP-CAD drawing showing the gate valve

11.3 The Solenoid valve- chosen valve for the control system

Principle of operation

Solenoid valve is an electromechanical valve for use with liquid or gas controlled by

running an electric current through a solenoid, which is a coil of wire, thus changing the

state of the valve. The operation of a solenoid valve is similar to that of a light switch, but

typically controls the flow of air or water, whereas a light switch typically controls the

flow of electricity.

Solenoid valves may have two or more ports: in the case of a two-port valve the flow is

switched on or off; in the case of a three-port valve, the outflow is switched between the

two outlet ports. Multiple solenoid valves can be placed together on manifold. Solenoid

valves are the most frequently used control elements in fluidics.

Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many

application areas. Solenoids offer fast and safe switching, high reliability, long service

life, good medium compatibility of the materials used, low control power and compact

design.

Besides the plunger-type actuator, which is used most frequently, pivoted-armature

actuators and rocker actuators are also used.

The structure

A solenoid valve has two main parts: the solenoid and the valve. The solenoid converts

electrical energy into mechanical energy which, in turn, opens or closes the valve

mechanically.

Solenoid valves may use metal seals or rubber seals, and may also have electrical


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interfaces to allow for easy control. A spring may be used to hold the valve opened or

closed while the valve is not activated.


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70


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The cross-section showing the finer details of a solenoid valve and its

construction. From the diagram one can deduce that the opening and

closing of the valve has a great relationship with the energizing and

de-energizing of the coil.

This is a SAP-CAD drawing which uses mainly ACAD2004

THE SOLENOID VALVE


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11.4 Justification of my choice

For my design I am going to use a 2-way solenoid valve to totally open or totally close

thereby restricting the pneumatic signal required by the pneumatic grease pump during

lubrication. The solenoid valves are controlled by an electrical signal from the SCADA.

Improved Control




performance.

Enhanced Safety

You can check instrument and valve operation and keep the process running

smoothly and safely from a remote location. Access is possible at a field junction

box, marshalling panel, or within the safety of the control room using a system

workstation. Your exposure to hazardous environments is minimized and you can

avoid having to access hard-to-reach high temperature locations.

Hardware Savings

Solenoid valve, when used in an integrated system, allow you to realize


process loop, such as positioners and limit switches, with just opening or closing

of the valve by the movement of coil.

Easy Maintenance

Solenoid valves are modular in design. The module base can be removed from the

instrument housing without disconnecting the field wiring, pneumatic connections

or stem linkages. This module contains the critical sub-modules so component

removal is quick and simple.


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CHAPTER 12

The Calculations

The Equation of Continuity as statement of mass conservation

The Law of Conversation of mass states that mass can be neither created nor destroyed.

Using the Mass Conversation Law on a steady flow process - flow where the flow rate

don't change over time - through a control volume where the stored mass in the control

volume don't change - implements that inflow equals outflow.

This statement is called the Equation of Continuity.

Common application where the Equation of Continuity can be used are pipes, tubes and

ducts with flowing fluids and gases, rivers, overall processes as power plants, diaries,

logistics in general, roads, computer networks and semiconductor technology and more.

The Equation of Continuity and can be expressed as:

m = ρi1 vi1 Ai1 + ρi2 vi2 Ai2 +..+ ρin vin Aim

= ρo1 vo1 Ao1 + ρo2 vo2 Ao2 +..+ ρom vom Aom (1)

where

m = mass flow rate (kg/s)

ρ = density (kg/m3)

v = speed (m/s)

A = area (m2)


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With uniform density equation (1) can be modified to

q = vi1 Ai1 + vi2 Ai2 +..+ vin Aim

= vo1 Ao1 + vo2 Ao2 +..+ vom Aom (2)

Where

q = flow rate (m3/s)

ρi1 = ρi2 = ρin = ρo1 = ρo2 = ρom

Pipe equations

Calculating cross-sectional area, weight of empty pipes, weight of pipes filled

with grease, inside and outside surface area.

Pipe cross-sectional area, empty pipe weight, pipe filled with water weight, inside and

outside pipe surface area for a unit length pipe can be calculated with the equations

below.

Cross Sectional Area

Cross-sectional Area of a Steel Pipe can be calculated as

A = 0.785 di 2

where

A = cross-sectional area of pipe (Square Inches)

di = inside diameter (inches)


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Weight of Empty Steel Pipes

Weight of empty steel pipes can be calculated as

wp = 10.6802 t (do - t)

where

wp =weight of steel pipe (Pounds per Foot Pipe)

t = pipe wall thickness (Inches)

do = outside diameter (inches)

Weight of Water in Pipes filled with Water

Weight of water in pipes filled with water can be calculated as

ww = 0.3405 di 2

where

ww = weight of steel pipe filled with water (Pounds per Foot Pipe)


Outside Surface Area of Pipes

Outside surface area of steel pipes can be calculated as

Ao = 0.2618 do

where

Ao = outside area of pipe - per foot (Square Feet)


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Inside Surface Area of Pipes

Inside surface area of steel pipes can be calculated as

Ai = 0.2618 di

where

Ai = inside area of pipe - per foot (Square Feet)


Area of the Metal

Area of the metal can be calculated as

Am = 0.785 (do 2 - di 2)

where

Am = area of the metal (Square inches)



Lubrication intervals calculations

After research using statistical data available and gathering information from the

Mechanical Supervisors at the plant I managed to deduce that lubrication of the Kiln

Sleeves is done after every 2 hours. I deduced the following calculations using my

design parameters.

Lubrication interval = 2hours


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Pump capacity = 1L/min

Sleeve requirements = 1L/2hrs

Total number of switching ON of pump per day:

Total litres of lubricant pumped per day:

= 12 Litres

Lubricant container volume = 210 Litres.

Total number of days the lubricant can be applied before refill:

Therefore the system can run up to a maximum of 388 hours before refilling the

container.

Fail Safe Mode of the Control System

Total number of liters: 210 Litres

Residual volume of lubricant after 388 hours:

Thus the total number of lubrication intervals that can be attained after an alarm for

refilling the tank has been flagged are:


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The total number of hours the pneumatic pump can be operational before automatically

switching OFF even when the tank is not refilled are:

The timers in the circuit were used to attain the “fail safe mode” of the whole project.

Engineering thermodynamics as applied to the automatic lubrication system design

project.

Calculations

Consider a small interval of time and small mass of lubricant entering the system

and small amount of work done by the pump given that the energy of the system is Es.

Assumptions

To facilitate the application of Laws of Thermodynamics to this lubrication system lets

consider a closed system, knowing that the lubricant is filled in the tank at a different

activity with draining the lubricant for application.

At time = ( )

The differential change of State

Assume all properties of the lubricant are uniform during filling the container and

of lubricant.

Then

Thus the first Law of Closed system can be stated as follows,

Hence at time t the total energy ET of the system is given by,


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And at time ( ) the equation becomes.

The workdone in time dt is equal to the workdone by the pump shaft plus flow work.

Therefore the work transfer turn on the pump shaft is given by the shaft work and the

flow work

The flow work can be expressed as follows,

Substituting relevant expressions we deduce the following,

From the equation on the previous page I can substitute for enthalpy then divide by

dt having in consideration that my system has one inlet and one outlet.

Final Assumptions

Assume there is no boundary movement.

Mass flow rate of the system is constant and the same at inlet and outlet.

Properties of fluid at any point in the system remain constant with time.

Heat and work across boundaries of the system are at a constant rate.

CHAPTER 13


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The Schematic Wiring Representation of the Project.


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13.1 The Parts list

NB: most of the parts on the list are the main parts hence some bolts and nuts are not

listed down so during installation please make use of the cost analysis table at the end of

this write up.

CHAPTER 14

Interfacing with SCADA- Cimpilicity Software

Drawing the Object using CIMPLICITY Software

o Go to new Project then click Enter.

o Go to symbols and import the necessary symbols to form the object.

o Choose correct colours

NB: Knowledge of AUTOCAD or Microsoft picture editor is a requirement.

Creating object CIMPLICITY Software

Select Object Properties.


PartNumber

Name of Component Quantity

9 Backflow valve 18 Distribution container 17 Strainer 16 Lubricant storage tank 15 Pneumatic grease pump 14 Control valve/pressure transmitter 13 Solenoid valve 12 Pressure regulator 11 Isolating valve 6

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Declare the addresses that was used on the Ladder Logic Programme i.e. %M this

will enable the CIMPLICITY Software to identify the signal status from the

Ladder Programme.

Colour Animation

Colours can be imported from the colour folder hence there is need to clearly

analyse the feasibility of your addresses especially internal memory signals.

START: %M001 Hold-in Contact

%M001 [0] Gray (with all downstream interlocks OK)

%M001 [1] Green (the pneumatic pump will be pumping)

STOP: %M002 Auxiliary Contact

%M002 [0] Gray (with all interlocks in good condition, no EMEGENCY switch ON)

%M002 [1] Red (the pneumatic pump will not be pumping and the system is OFF)

PUMP COLOUR: %M003

%M003 [0] Red (the Control system is OFF)

%M003 [1] Green (the Control system is ON)

CHAPTER 15

Maintainability

My main concern was to ensure that my project would not become a liability for the

company because of unnecessary breakdowns and easy wear and tear of instruments, on

selecting each and every component in the system I did analysed the strength of material

used and whether it can survive in such a rugged condition.


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I do not hesitate to note that my system design is easy to maintain since the solenoid

valves that I used are the same as those already in use at the plant, of which I can say they

are easy to maintain.

My system does not require special skills to implement it or to use it, therefore there is no

need to retrain the Control room operators or instruments Technicians on how best to run

the automated lubrication system.

On the other hand this system is “automatic” so there is minimum- to- no human

interference so its maintainability is easier than any control system at the plant as no

routine work is done on it.

During production the whole system can easily be maintained because the pneumatic

pump does not have down stream interlocks with other plant circuits as compared to

drives and other machinery at the plant. Thus one can easily change the solenoid valve or

pneumatic pump during plant RUN.

During shutdown the total time required to service the whole Lubrication system is

minimum as compared to other control systems at the plant.

CHAPTER 16

Recommendations

While selecting the type of tubing to be implemented I had problems on locating the

rubber tube so I recommend that all the tubes be done using steel pipes which can

withstand high pressures.


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Installation of instruments which uses pneumatic signals has always been a challenge to

most Technicians so I recommend that during installation of this system a pipe fitter be

present and also no leakages should be allowed as this can cause some energy loses as

well as wastage of precious compressed air.

The lubricant is ordered in 25litre containers which will in turn be opened and used to

refill the 210 Litre main Lubricant tank, I recommend that 210 Litre containers be bought

directly from the supplier, and then the pneumatic pump may simply be installed at the

containers.

Although it was easy to come up with solutions there had been difficulties in choosing

the best solution as the company authority restricted my solutions to those with the

resources which are already available so as to cut the project total cost, I however

recommend that there should be no restriction on possible solutions as long as they are

feasible hence the company have to be in a position to meet some extra cost.

CHAPTER 17

REFERENCES

[1] SIMBI information desk.

[2] www.zim.steelmakers.com/simbi

[3] SIMBI information desk.

[4] Mr. I. Muchimwe (STEELMAKERS Group Instruments Engineer)

[5] Engineering Design and Innovation Lecture notes from the Mr. T Zhuga.

[6] Introduction to Tribology by D.Bargarao.


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[7] Tribology Analysis by Professor da Vinci University of Twentwe. (U.T)


[9] www.industriallubricants.com/grease


[11] Introduction to Thermal Expansion Vol.2 by W. Gupta

[12] Tribology Analysis by Professor da Vinci University of Twentwe. (U.T)

[13] Fluid Power and Drives Lecture notes by Mr. D. Wakasemwa



[16] Introduction to Thermal Expansion Vol.2 by W. Gupta

[17] www.industriallubricants.com/lubrication

[18] Introduction to Tribology by D.Bargarao

[19] www.valves.com/solenoid

[20] Intelligent Machine and Interfacing Lecture Notes by Mr. T. Zhuga

[21] Industrial Automation Lecture Notes by Mr. T. Zhuga

[22] Intelligent Machine and Interfacing Lecture Notes by Mr. T. Zhuga

NB: all calculations were done using the combination of notes from my tutorials that

I had attended at C.U.T.

CHAPTER 18


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Conclusion

In conclusion the main objective of this project was to come up with the solution for

lubricating the kiln and cooler sleeves of which I believe I did. This project was more

difficult than the one I did at the University in my 2nd Year because I had to focus on

implementation of the system too rather than coming up with just a write up of the

project.

Installation and commissioning of this project is due on the next plant-shutdown of which

by then I would have submitted the write up to the Department of Mechatronics at CUT.

However with the vast exposure I had in Control Systems I do believe the Installation and Commissioning of this project is going to be easy since I also have worked with the Instruments Engineer- Mr. I Muchimwe, Mechanical Supervisor- Mr. B. Bvude and the Process Engineers – Mr. Ravi Kumar and Mr. E Mugodi so as to come up with the write up.The project actually presented an opportunity to combine the knowledge that I had gained from my Lectures at University and the practical work that I had carried out on my attachment at the company. Also I had the opportunity to learn much on how to gather relevant information from field experts.

At this point it was now clear to me that coming up with an industrial solution to a problem requires team work.

This project was so difficult to come up with since researching using the internet was too expensive and I was also too busy since I was now employed as an Instrumentation and Control Technician.

To a greater extent this project was successful on solving the project at hand.


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Talon Garikayi c056634k- Final Automated Lubrication System Project for Simbi Plant With Cover Page...

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