1. MASINDE MULIRO UNIVERSITY OF SCIENCE AND TECHNOLOGY
Field attachment practice report 2013
NAME: DADDIE C. OBARA
REG NO: MIE/0022/10
COURSE CODE: MIE 390
COURSE TITLE: Field attachment
DEPARTMENT: MECHANICAL & INDUSTRIAL ENGINEERING
ATTACHMENT
PERIOD: THREE MONTH (JUNE – AUGUST) 2013
NAME OF THE ORGANISATION: MUMIAS SUGAR COMPANY

2. ii
DECLARATION
I hereby declare that, this is my personal report of industrial attachment at Mumias Sugar
Company. I have compiled it myself and it has never been presented before at any level
of education. It is a pure reflection of what I learned at Mumias Sugar Company during
the period I have been on my attachment for a period of 12 weeks.
.
Sign: ______________________________
Date: _________20/10/2013____________

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ACKNOWLEDGEMENT.
My sincere acknowledgement goes to Almighty God for provision and protection
throughout my attachment. I owe nothing to myself.
The presence and valuable assistance of several people who made the attachment
period effective and even shorter. I appreciate all the help I got from my supervisor Eng.
David Achilah who was in charge of the Mumias Sugar Company Process House; Thank
you or the moral support you were not only a supervisor to me but also a mentor a
source of inspiration and a spring of patience.
Not forgetting Masinde Baraza, Daniel Ogenga who were my university supervisor, for
the guidance they gave me during the supervision period
Lastly to my parents saying thank you may not be enough but I hope it conveys the
message of my heart for the support both financially and emotionally. Thank you a lot.
I would like to acknowledge the invaluable guidance, concern and support of the
technicians. During the workshop practice they always accepted my ideas with an open
mind and gave me the opportunity to learn and apply. Their advice helped to refine the
practical application.
I would like to thank the entire faculty of engineering in particular the department of
production engineering for providing facilities and conducive environment throughout
the Field Attachment Practice.

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ABSTRACT
Field Attachment practice involves application of theory into practical by use of
machines. This report entails all that was carried out during the Field Attachment
practice, detailed research that was carried out in order to expound on the operations
carried out. The main practices carried out during the Field Attachment practice in the
production department are machining and welding.
This report covers different areas in factory department where different operations take
place (plant and production operations) such as the company, giving its brief introduction
and location, the activities it deals with, the sections that I passed through and the skills
learned in each section. The report also highlights the company’s areas of strength that
contributes to its prosperity that are worth aping. At the end of the report the technical
problems noted in the firm are highlighted and a solution given to at least one of these
technical problems.

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TABLE OF CONTENTS
DECLARATION...............................................................................................................................ii
ACKNOWLEDGEMENT. ................................................................................................................iii
ABSTRACT....................................................................................................................................iv
TABLE OF CONTENTS....................................................................................................................v
LIST OF TABLES ...........................................................................................................................vii
LIST OF FIGURES .........................................................................................................................vii
CHAPTER 1.............................................................................................................................1
1.1 INTRODUCTION ..................................................................................................................... 1
1.1.1 Company vision: ............................................................................................................. 2
1.1.2 Company mission: .......................................................................................................... 2
1.1.3 Company values: ............................................................................................................ 2
1.1.4 Company’s History in Summary ..................................................................................... 2
1.1.5 The organization............................................................................................................. 5
1.1.6 Quality Control ............................................................................................................... 6
1.1.7 ISO Standards ................................................................................................................. 6
1.2 Aims and objectives of industrial attachment....................................................................... 6
1.3 Attachment time table .......................................................................................................... 6
CHAPTER 2.............................................................................................................................7
2.1 THE WORKSHOP .................................................................................................................... 7
2.1.1 The Pattern Shop............................................................................................................ 7
2.1.2 The Foundry House......................................................................................................... 7
2.1.3 Lathe and Machining Section ......................................................................................... 8
2.1.4 Welding and Fabrication .............................................................................................. 12
2.2 CANE PREPARATION, THE DIFFUSER AND DEWATERING MILLS ......................................... 15
2.2.1 Cane preparation.......................................................................................................... 15
2.2.2 The Diffuser .................................................................................................................. 17
2.2.3 Milling (Dewatering Mills) ............................................................................................ 19
2.2.4 The Power House.......................................................................................................... 20
2.3 THE BOILERS SECTION ......................................................................................................... 22
2.4.1 Steam Generation......................................................................................................... 22

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2.4.2 Source of fuel for the boilers........................................................................................ 22
2.4.3. Use of the boilers ........................................................................................................ 22
2.4.4 Boiler types................................................................................................................... 23
2.4.5 Boiler feed water and its quality .................................................................................. 23
2.4.6 Steam generation trends.............................................................................................. 25
2.4.7 Working principle of boiler........................................................................................... 25
2.4.8 Equipment and accessories of a modern boiler plant.................................................. 26
2.4.9 Mumias Sugar Company Boiler Plant Systems............................................................. 27
2.5 PROCESS HOUSE OPERATIONS............................................................................................ 31
2.5.1 Juice Treatment............................................................................................................ 31
2.5.2 Evaporation .................................................................................................................. 32
2.3.4 Sugar House Section.............................................................................................. 37
2.5.4. Packaging Plant............................................................................................................ 42
2.5.5 Air Compressors ........................................................................................................... 45
CHAPTER THREE...................................................................................................................46
3.1 Some of the indentified problems and some remedies...................................................... 46
3.1.1 The nature of frequent break downs experienced in cane preparation process......... 46
3.1.2 The major problems experienced in boiler section are; ....................................... 46
2.1.3 Frequent problems encountered with the pumps and some of their remedies. ........ 48
3.1.4 Frequent problems experienced on the packaging machines ..................................... 49
3.2 RECOMMENDATION............................................................................................................ 50
3.3 CONCLUSION ....................................................................................................................... 51
REFFERENCES.......................................................................................................................51
APPENDIX............................................................................................................................53
FACTORY ORGANIZATION.......................................................................................................... 53

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LIST OF TABLES
Table 1: Company’s History in Summary......................................................................................... 2
Table 2:Attachment time table ....................................................................................................... 6
Table 3 : Pumps used in the process house .................................................................................. 35
LIST OF FIGURES
Figure 1: Lathe machine .................................................................................................................. 9
Figure 2: Milling machine.............................................................................................................. 10
Figure 3: Arc welding..................................................................................................................... 12
Figure 4 : Gas welding ................................................................................................................... 13
Figure 5: Some parts of the MIG machine..................................................................................... 13
Figure 6: TIG Welding ................................................................................................................... 14
Figure 7: Submerged Arc Welding................................................................................................. 14
Figure 8: Soldering......................................................................................................................... 15
Figure 9: Dewatering Mills............................................................................................................. 19
Figure 10: working principle of boiler ........................................................................................... 25
Figure 11: Bagasse system conveyors ........................................................................................... 28
Figure 12 : Flow diagram of juice treatment and equipment used............................................... 31
Figure 13: Flow diagram of the pan boiling process ..................................................................... 37
Figure 14: Flow Diagram of Sugar Bagging, Packaging and Warehousing .................................... 43

8. 1
CHAPTER 1
1.1 INTRODUCTION
Mumias Sugar Company is situated in the western province of Kenya, Butere-Mumias
district. The company was started in 1973, with the aim of making the country self
sufficient in “plantation’ white sugar. The factory has grown, over the years, with a
change in management, design improvements and scale of production.
The location of this factory was enhanced by such factors as:
 Ample land for premise construction
 Presence of sufficient water from river Nzoia
 Enough manpower from the surrounding community
 Availability of enough sugar cane (raw materials)
 Enough capital
The company is, so far, the leading white sugar producer in East and Central
Africa, following the introduction of the diffuser, in1997. In Kenya, Mumias Sugar
Company competes with other companies like Nzoia, Sony (South Nyanza), Chemilil,
Muhoroni and West Kenya .It produces about 45% of the sugar sold locally.
Five well-knit departments run this organization namely:
• Production
• Quality control and assurance
• Engineering
• Human resource and
• Finance
The factory crushes about 350 tonnes of cane per hour, with a daily delivery of
cane of about 8,000 tonnes. This appears as sugar at a rate of about 32 tonnes per hour.
Three main products are obtained at the end of the process; Bagasse, plantation white
sugar and final molasses.
Bagasse is the source of fuel for the boilers, while sugar and molasses are sold to the
market. This report covers the work done in the production section and other affiliate
parts. Various unit operations and process procedures are covered in this report with the
necessary recommendations and conclusion made.
Mumias Sugar is a sugar manufacturing company located in Mumias 32KM from
Kakamega town along Bungoma road. Its headquarters is based in Nairobi. It was started
in 1971 by Mumias Sugar Company body incorporated by the Kenyan Government to

9. 2
implement it as a pilot project, whose feasibility study by Booker Agriculture and
Technical Services had proven successful. The raw materials for Mumias Sugar Company
are cane. The cane that is processed at the Company comes from its own Nucleus estate
(10%) and the remaining 90% from Indigenous Out growers farmers with over 400 km
under cultivation who are contracted by the company. Mumias Sugar Company in its
leadership role in the industry has diversified into power, water and ethanol production.
The company currently produces 34MW of electricity of which 26MW is exported to the
national grid. It is also expected to produce 24 million litres of water and 22 million litres
of Ethanol per annum. Mumias still maintains its dominance in the sugar Manufacturing
sector with a 60% market share.
1.1.1 Company vision:
To be a world class integrated producer of sugar, green energy and related products.
1.1.2 Company mission:
To consistently satisfy consumer needs through efficient, innovative and ethical
practices while meeting the diverse expectations of other stakeholders.
1.1.3 Company values:
 Quality products and services to our customers.
 Excellence in team driven performance.
 Ethical business practices
 Responsible cooperate citizenship
 Safe, healthy and sound environment practices
1.1.4 Company’s History in Summary
Table 1: Company’s History in Summary
1967 The government commissioned a subsidiary of Booker McConnell, Booker
Agricultural & Technical Services, which is now BTL, to study the feasibility
of growing cane at Mumias and to initiate a pilot project.
1971 Study concluded that it is possible to establish a viable sugar scheme at
Mumias with a factory supplied with cane from both nucleus estate and out
grower cane farmers through an out growers scheme. Commencement of
cane planting on the nucleus estate and out grower areas.

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1973 First sugar produced by the company
1976 Expansion of milling capacity from 80 tons of cane per hour to 125 tons of
cane per hour.
1979 The company decided to proceed with an expansion of factory capacity to
300 tons of cane per hour, an expansion equivalent to the construction of
large new factory. Contractors for the supply and erection of this extension
were signed.
1985 Completion of expansion of the factory, giving the company a potential
capacity of 210,000 tons of sugar per year.
1995 Commencement of factory rationalization project
1997 Completion of factory rationalization project which consisted of erection of
a new 110 tones per hour boiler, 7.0MW turbo alternator, a juice clarifier,
heaters & juice evaporators, new diffuser and cane handling equipment and
de-watering mills. Daily milling capacity increased to 7000 tons per day and
efficiency of sucrose extraction raised from 82% to 86%.
1999 Staff rationalization through a voluntary early retirement scheme that
reduced the permanent workforce from 4,650 employees to 3,400
employees by October 2000.
2000 Establishment of a nationwide distribution network for sales and
marketing, and branding a product in 2kg packaging. Concluded power sale
an agreement with Kenya Power and Lighting Company to Supply
10,000MWh of electricity per annum to the national grid.
2001 Conversion of company from a private to a public company and listing on
the Nairobi Stock Exchange.
2002 Considerable increases in sales of branded sugar in Wake of Sugar price
declines.

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2003 Expiry of management contact with Booker Tate and subsequently Dr.
Evans Kidero appointed as Managing Director
2004 Highest profit after tax results since inception. 11% growth in cane
processed and Sugar produced. Factory achieved production of 264000
Metric tons. Strengthened distribution network leading to increased
market penetration. This ensured availability of Mumias Sugar in all parts
of the Country. Doubled branding packaging Capacity and introduced the
1/4kg and 1/2kg packets. Finalized plans to invest in capacity expansion.
2005 Highest production by the Company (269,184 metric tons) since inception.
Board approved strategic plan to exploit co-generation opportunities and
establish an ethanol plant. Factory refurbishment undertaken to enhance
factory capacity to 410 tons of cane per hour. Signed contract with KPLC to
supply 2MW of electricity to the National Grid.
2006 Embarked on a project to increase its production capacity to 300000 tons
per annum. Signed an agreement with Avant Grade Engineers and
consultants (p) Ltd of India to put up a USD 40M power production unit
which will see its generating capability increased to 35 MW and enable the
Company to sell to 25mw to the National Grid. The Company entered into
a ten year agreement (2009-2019) with Japanese Carbon Finance Company
Limited. This arrangement should see the Company receive “Carbon
credits” as a result of replacing thermal production of electricity with the
more environmentally friendly “baggase” production. The Company will
then exchange these credits for hard currency. Power-Cogeneration was
Completed by January 2009. The Ethanol project started March 2009.

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1.1.5 The organization

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1.1.6 Quality Control
Mumias sugar company beliefs in the quality of the products they produce since that is the only
way they would beat their competitors. It enjoys the monopoly of being the leading company in
east and central Africa of producing quality sugar. It has department under factory operations
that deals only with the quality of the sugar they produce to meet customers’ needs and also
ensure that the sugar meets pertinent codes or standards. The department is being headed by
quality control specialist. Grade one of the sugars which is being produced is packed and sold to
the suppliers where they distribute locally or outside the country and grade two is being sold
locally to small retailers.
1.1.7 ISO Standards
The company provides 60% of Kenya’s sugar through appointed distributors countrywide. It also
exports some of its sugar to international markets mainly in the European Union. The company
has ensured that the quality of the sugar meet the international standards or internationally
recognized institutions. Locally the standards to be made is formulated by Kenya Bureaus of
Standards (KEBS)
1.2 Aims and objectives of industrial attachment
 It provided a practical blend of content learned in class and its application.
 It facilitates understanding the working principles of machines.
 It gives base for industrial attachment preparation.
 It facilitated fulfillment of the degree course.
 Familiarize with the environment of their profession
 Identifying engineering problem then coming up with a remedy solution
 Acquire the practical skills pertaining their profession
 Relate the theoretical phenomena learned in class with their practical application
 Create a rapport with their potential future employers after completion of studies.
1.3 Attachment time table
Table 2:Attachment time table
Workshop Extraction Boilers Process
FROM: 03-06-2013 03-07-2013 18-07-2013 6-08-2013
TO: 03-07-2013 17-07-2013 2-08-2013 29-08-2013

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CHAPTER 2
This chapter has covered sugar processing processes from the receiving of canes in the industry
to coming up with the final products which is sugar.
FACTORY SECTIONS
The factory has four sections which include boiler, extraction, process and workshop.
2.1 THE WORKSHOP
The workshop deals majorly with the production of the spares required for various components
within the plant. Therefore this section makes use of various methods of production to achieve
this. It is for this reason that this section is subdivided into the following subsections;
o Pattern shop
o Foundry house
o Lathe and machining section
o Welding and fabrication section
o Pump and gear box overhaul section
2.1.1 The Pattern Shop
The pattern shop is concerned with the design of models of the components having intricate
shapes that can hence not be fabricated by machining. The models thus produced in the pattern
shop are produced by casting in the foundry shop.
The pattern shop thus has a library that houses already designed models that are usually used in
the molding process. The patterns are made in such a way that they are split into 2, 3 or 4 pieces
to allow for their withdrawal without breaking the molding clay during the molding and casing
process.
The models used are made from well-seasoned hard wood so as to produce durable patterns. In
some instances light non-ferrous metals such as aluminum are also used.
2.1.2 The Foundry House
The foundry house does the molding and production of metallic non-ferrous components
through the process of casting. A pattern desired for production is obtained from the pattern
shop and then placed in a molding then molding sand is rammed into the box to the required
quality. The boxes used are two namely the cope box and the drag box. The pattern is placed in
the drag box and after withdrawal the cavity is thus left there. The cope box just helps to cut the
gate ways through it so as to help the molten metal flow easily though the boxes and rise in the
cavities created.

15. 8
The ingots produced here are taken for machining to bring them to the required dimensions.
2.1.3 Lathe and Machining Section
1. Machining processes
Machining is the most important of the manufacturing processes .machining can be defined as
the process of removing material from a work piece in the form of chips. The term metal
cutting is used when the material is metallic. Most machining has very low set-up compared
cost compared to forming, molding and casting processes. Machining is necessary where tight
tolerance on dimensions and finishes are required.
Machining section is divided into the following categories;
a) Facing
This operation was essential for all works. The facing tool is used and it removes metal by
side cutting the edges and no top rake is required. The operation of facing involves feeding
the tool perpendicular to the axis of rotation of the work piece. The cutting edge is set at
the same height as the cutting of the work piece.
b) Turning
This is the operation to remove material from the outside diameter of a work piece to
obtain a finished surface. The work piece is mounted on a chuck or between centers and
the axis of the work piece is kept centrally to the axis of the lathe. The tool used is clamped
on the tool post. The cutting edge of the tool is kept at the lathe axis. By adjusting the feed
either manual or automatic the carriage is moved to the desired length at the end of which
the feed is disengaged and carriage brought back to initial position.
c) Chamfering/Taper turning
This is the operation of producing a conical surface on a work piece. Chamfering tool is used
in this operation. The compound rest is swiveled to the required angle and clamped in
position. The taper is turned by hand wheel by rotating the handle. The work piece is held in
a chuck.
d) Drilling
Drilling is the operation of making a hole in a work piece where none previously existed.
This is done on the lathe by holding the drill in the tailstock quill. The shank of the drill is
held in the tapered hole of the quill. The job is held in a chuck and the tools fed to the
revolving work piece by the quill by rotating the tailstock handle.
e) Boring
This is the operation of enlarging the drilled hole. The work piece is held in the chuck in the
lathe spindle and the boring bar is mounted in the tool post. Boring is done by moving the
carriage towards the headstock.

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f) Under-cutting
This is the operation of reducing the diameter of the work piece over a small surface. A tool
of appropriate length held on the tool post is fed in the revolving work to the desired depth
at right angles to the centerline of the work piece. This was applied before cutting threads
on the female part of the stuffing box. This helps in determining the depth of the threads
appropriately.
g) Knurling
It is the operation of plastically displacing metal into a particular pattern for the purpose of
creating a hand grip or roughened surface on a work piece. The knurling tool is held in the
tool post and is pressed against the surface of the work piece by cross feed. In this
operation the knurling tool is used.
h) Thread cutting
This should be the last operation to be performed on a work piece. Thread cutting comes
into operation when the diameter of the screwed portion has been turned down to the top
size of the thread and change wheel fitted. Threads are formed by the rotation of lead
screw when it transverses the tool along the work.
1. Lathe machine
Figure 1: Lathe machine
Lathe is a machine for shaping a work piece by gripping it in a holding device and rotating it
under power against a suitable cutting tool for turning, boring, facing, or threading. A lathe
consists of a bed, a headstock, a carriage slide, a cross slide, a tool holder mounted on the cross
slide, and a source of power for rotating the work piece.

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Milling Machine
Figure 2: Milling machine
A milling machine is a machine tool used for the complex shaping of metal and other solid
materials. Its basic form is that of a rotating cutter or end mill which rotates about the spindle
axis (similar to a drill), and a movable table to which the work piece is affixed.
That is to say the cutting tool generally remains stationary (except for its rotation) while the
work piece moves to accomplish the cutting action. Milling machines may be operated
manually or under computer numerical control.
Milling machines can perform a vast number of complex operations, such as slot cutting,
planning, drilling, rebating, routing, etc.
Cutting fluid is often pumped to the cutting site to cool and lubricate the cut, and to sluice away
the resulting swarf.
It is a machine tool used in removing metal as the work is fed against a rotating multipoint
centre.
Operation on milling machine
 Drilling -It is producing a circular hole in a solid metal by revolving tool known as drill
 Reaming -It expands existing holes slightly, to produce tightly tolerance holes
 Boring-It consists of enlarging only a portion of the hole. The operation is performed by a
double tool boring bar or by counter boring.

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 Counter sinking-A hole with the top part enlarged so that the head of the screw or bolt will lie
flush or below the surface.
 Spot facing-It is used for squaring and finishing the surface around and at the end of a hole to
provide a smooth and true seat to the underside of the bolt head.
 Tapping-It is the operation performed for internal threads with the help of a tool call ‘tap”. For
performing this operation machine should have a reversible motor or some other reversing
machine. A collapsible-type tapping attachment can be used.
3. Grinding machine
For fair finish of the work piece the extra material is removed by abrasive action of the
revolving wheel performed on the surface of the work piece. The wheel which performs
operation of removal of extra material is known as ‘grinding wheel’ and the machine to which
the wheel is attached is known as grinder.
Grinding wheel
The grinding wheel operates on the surface of the work piece which has already been given
more or less its final shape by one of the machines to which the cutting tool is fitted.
These wheels are made from abrasive grains kept in position with the help of suitable binding
material known as –the ‘BOND’. The abrasive materials are mixed with suitable bond. This
‘bond’ functions as the matrix or holder when the wheel is used.
Abrasives
The abrasive used for bonding fall under two categories namely ‘natural abrasive’ and ‘artificial
abrasive’.
The natural abrasives used are:
 Sandstone and quartz are the general cutting agents
 Emery: it is a natural aluminium oxide having oxide 75 to 65% alumina along with iron
oxide and other impurities.
 Corundum: it is a natural aluminium oxide having 75 to 95% alumina and the rest
impurities.
 Diamond
Used for making grinding wheels for grinding cemented carbide tools and for the
purpose of making lapping compound.
The artificial varieties of abrasive are:
 Silicon carbide
 Aluminium oxide
It is used for grinding hardened tool steel component.
 Artificial diamond
They are produce artificially

19. 12
2.1.4 Welding and Fabrication
This subsection is concerned with production through welding and fabrication and also repair
and maintenance of parts and components by welding. Metal arc welding is the main mode of
welding used in this section while gas is mainly used for cutting. Pipes, reducers and other
components required are also fabricated here. The other welding done in this section is:
1. Arc welding
Figure 3: Arc welding
Arc welding is a process that uses an electric arc to join the metals being welded. A distinct
advantage of arc welding over gas welding is the concentration of heat. In gas welding the
flame spreads over a large area, sometimes causing heat distortion.
The concentration of heat, characteristic of arc welding, is an advantage because less heat
spread reduces buckling and warping. This heat concentration also increases the depth of
penetration and speeds up the welding operation; therefore, you will find that arc welding is
often more practical and economical than gas welding. All arc-welding processes have three
things in common: a heat source, filler metal, and shielding.
The source of heat in arc welding is produced by the arcing of an electrical current between
two contacts. The power source is called a welding machine or simply, a welder. This should not
be confined with the same term that is also used to describe the person who is performing the
welding operation. The welder (welding machine) is either electric- or motor-powered. In the
Naval Construction Force (NCF), there are two main types of arc-welding processes with which
you should become familiar. They are shielded metal arc welding and gas shielded arc welding.
2. Gas welding

20. 13
Figure 4 : Gas welding
Burning a fuel gas with air, as in a simple gas blow torch, will not give enough temperatures for
welding. The gas is burned with oxygen. The most common fuel is acetylene, hydrogen and
propane
3. MIG Welding
Figure 5: Some parts of the MIG machine
This is Metal inert Gas. Have in common the electrode used as the filler wire which is
continuously fed and heating the job with an arch is established on the work, total or partial inert
gas used for shielding the produced arc. There is no flux used for weld, helium, argon, carbon-
dioxide or some gas mixture is used to shield for the arc and molten metal from atmosphere.
4. TIG Welding

21. 14
Figure 6: TIG Welding
This is Tungsten inert Gas welding. In TIG Welding the inert gases are used. The arc is maintained
between the tip of tungsten which worked as an electrode and work piece. A special type
electrode holder is made for the inert gases spread on the weld bid concentrically. The tungsten
non-consumable electrodes are used for tig weld. The filler rod is additionally added to the weld
joint. This process AC or DC may be used which depends upon the type of metal to be welded.
The direct current with straight polarity is used to welding Copper or its alloys Stainless Steel and
reverse used for Magnesium.
5. Submerged Arc Welding
Figure 7: Submerged Arc Welding

22. 15
Uses heat generated by an arc formed when an electric current passes between a welding wire
and the work piece. The tip of the welding wire, the arc, and the weld joint are covered by a layer
of granular flux. The heat generated by the melts the wire, the base metal and the flux. The flux
shields the molten poor from atmospheric contamination, cleans impurities from the weld metal
and shapes the weld bead. Depending on the design of the flux, it can also add alloying elements
to the weld metal to alter the Chemical and Mechanical properties of the weld.
6. Soldering
Figure 8: Soldering
Soldering is a process in which two or more metal items are joined together by melting and
flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than
the work piece. Soldering differs from welding in that soldering does not involve melting the
work pieces.
2.2 CANE PREPARATION, THE DIFFUSER AND DEWATERING MILLS
2.2.1 Cane preparation
Objectives of cane preparation
1. Leveling of the cane mat to avoid chokes
2. To increase the bulk density of cane, thus increasing the capacity of the diffuser and mills
respectively.
3. To break down the hard cell structure (rind) of the cane.
4. To expose cells for easy juice extraction and increase the imbibitions dilution.

23. 16
2.1.2 Equipment used in cane preparation
1. Hydro-unloader/Gantry cranes /Wheel loaders
These equipment are used to load the feed tables, where feeding must be regular to avoid
overfeeding hence choking the knives.
2. Cane carriers; which convey cane to the knives.
3. The leveler knives
They consist of a steam turbine, driving a shaft on which knives are tightly bolted for cutting
cane, reducing the load to heavy-duty knives and leveling up the irregular heaps.
4. The heavy duty knives
The leveler and the heavy-duty knives mark the first stage of cane preparation. Leveler, levels the
cane so as to obtain uniform feeding before being fed to the heavy-duty knives.
Heavy-duty knives cut the cane into pieces.
The major parts or components
i) Rotor - This is the rotating element that is driven by the prime mover. The knives are
attached on the rotor.
ii) Locking Plate and Split pins - The knives are locked into the rotor by use of locking plates,
which are wedge like then secured using split pins.
iii) Drive - Both are driven by steam turbines
iv) Knives - Both knives are hard faced to increase their life i.e. reduce wear. The heavy-duty
knives are hard- faced to form a club-like head. They weigh about 12kgs.
v) Knives must be carefully weighed and balanced on opposing sides of rotor to avoid
Vibration
The nature of frequent break downs
i) knives coming off
When the knives encounters either a metallic object say arms of cane kicker, slat that has
come off, it is bound to break off. The tramp iron magnet arrests the knives that have
come off. If many knives have come off, the plant has to be stopped to replace them. A
hard rock in cane can also result in this breakdown.
ii) Worn out knives.
This happens especially during rainy seasons. Sand particles come with cane resulting in
severe wear due to abrasion. The preparation of cane becomes poor hence necessitating
stoppage and replacing the knives.
These reduce the cane to smaller pieces exposing cells for subsequent extraction at the
diffuser. This system consists of a steam turbine driving the shaft containing knives. The unit
has more knives than the leveler and tends to cover the entire surface of the carrier.
5. The shredder

24. 17
Facilitates complete disintegration of cane before entry into the diffuser.
The major parts
 Rotor and Shaft - Rotor is driven by the prime mover. The shaft is through which
the hammers are suspended.
 Hammers - The hammers swing on the rod. They are responsible for
disintegration of cane.
 Wash board and toggle springs. - The clearance between the knives and the
washboard is adjusted using toggle springs.
 Drive - Driven by a steam turbine
6. Feeder Drum
The feeder drum pushes the cane towards the heavy-duty knives. The feeder drum is driven by
an electric motor coupled to a gearbox. The gearbox is coupled to the chain drive that drives the
shaft of the drum.
The nature of frequent break downs
i) Cane leaks at the side.
This is as a result of wear on the rubber seal. Should be planned for replacement.
Routine daily checks and preventive measures
i) Check condition of bearings
For abnormal sound, open and inspect. Replace-seized bearings.
ii) Check condition of gearbox, foundation bolts, check looseness of the chain, check
Sealing rings.
Tighten loose foundation bolts. Tension chain if loose
iii) Check wear on the drum; inspect the condition of angle iron.
This is normally done during shut down. Re-build worn out angle irons.
iv) Listen to any abnormal sound from the feeder drum. This also best inspected during
maintenance shutdown.
v) Check V-belts and pulleys of motor and gear box
If belt loose, tension. Replace broken or worn-out pulley
Abnormal noise from the gearbox should be checked by inspection and rectifying
depending on the problem
2.2.2 The Diffuser
The diffuser is an enclosed carrier through which a bed of prepared cane is slowly dragged,
while copious quantities of water and thin juice percolate through the bed to wash out the pol-
bearing juice.

25. 18
True diffusion means diffusion of juice through unbroken cell walls; this is a slow process, and
in this case, juice removal involves washing pol (sucrose ) out of shredded cells, a process we
can call leaching.
Imbibition water
Imbibition water is one used for washing juice from cane. The fibrous residue is called
bagasse and is mainly used as fuel.
Imbibition water temperature is controlled well between the values 80-90’c to avoid growth of
leuconostoc bacteria which enhances inversion, an irreversible process.
Sucrose glucose + fructose
Cane juice is acidic in nature, having pH values of 3.5-4.5.Operating at low pH values can easily
corrode the plant components hindering operation at high temperatures. To avoid these
problems, lime (CAOH) is added at the 2
nd
and 7
th
stages of the diffuser to increase the pH (to
between 7 & 8).
Types of imbibitions
i. Simple Imbibition: This is affected by imbibing once at the dewatering mills (as seen later) to
avoid choking and increase capacity of the second mill.
ii. Compound Imbibition: This is done at the diffuser (and where multiple mills are applied).
Imbibition is done at the 12
th
stage of the diffuser, and then continuous serial imbibitions
done, with thin juice, backwards to the 1
st
stage. Concentrated juice (called draft juice) is
drawn from the 1
st
stage
and pumped to the treatment section.
Importance of imbibitions: It enables extraction and recovery of sucrose from the cane cells.
Factors that affect extraction:
1. Preparation (of the cane) where two aspects exists
a) Degree of fineness measured by the preparation index (PI) - the higher the PI value, the
better the extraction.
b) Type of preparation- Size of distribution and particle shape. It is dependent on cane
quality and influenced by relative amount of shredding and knifing. There should be
minimum separation of fines, which lead to a more open cane bed and higher juice
percolation rates.
2. Throughput: increase in throughput reduces residence time of cane in the diffuser and
extraction is affected directly. Better extraction is achieved by running at a steady throughput.

26. 19
3. Throughput evenness: The cane rate into the diffuser should be as steady and even as possible
leading to steadier and more efficient operation.
4. Flooding: This reduces extraction performance, and should be avoided at all times.
5. Juice flow system: Juice flow rates through each stage should be as high as possible; high flow
rate promotes the rate of extraction
6. Bed height excessively high or low levels should be avoided.
2.2.3 Milling (Dewatering Mills)
Milling is defined as the passage of prepared cane, which has gone through the diffuser, through
the dewatering mills.
Figure 9: Dewatering Mills
2.3.1 Milling equipment
A) Rollers
i. Feed roller: Is on the front side of each mill feeding the other rollers with cane.
ii. Top roller: Is usually under pressure to squeeze the juice at two points, that is, at
delivery and feed rollers.
iii. Delivery roller: This delivers bagasse from both mills.
B) Trash plate

27. 20
This is put between the feed roller and delivery roller to keep the fibre passing through the mills
under some pressure and prevent fibre from falling between the bottom rollers.
Factors that influence milling efficiency
1. Operational factors-like milling staff 2. Mill setting
3. Mechanical condition of the plant-grooves/length of rollers 5.Cane preparation
4. Design of the plant (number of rollers) 6. Pressure applied
8. Mill speeds in revolutions per min. (rpm) 7. Imbibition
9. Specific fiber loading 10. Steam pressure
C) Conveyors
There are basically two types of conveyors at MSC: Chain-slats conveyor and rubber conveyor.
Section 4 dealt with a chain and slats conveyor, ACC 107
The conveyors in the section are coded as C112, C116 and C117 where: -
C112 - Knifed cane conveyor
C116 - Shredder discharge conveyor
C117 - Shredder cane elevating conveyor.
Main components of conveyor
i) Head drum-Coupled on the driving unit for driving the conveyor.
ii) Tail Drum-The purpose of this is to return the conveyor
iii) Take up Unit.-This unit is used in tensioning of the conveyor by addition of weights. Found
in C112 and C117
iii) Idler Rollers-Set of three on the bottom that carries the material and a set of two on the
return. Purpose is to reduce friction by helping move the conveyor and also act as a support for
the conveyor
v) Rubber Skirting- Located at the sides of the conveyor, to prevent leakage of material,
material falling off.
vi) Belt Scraper- Located after the drive, to scrap off material on the return path of the conveyor.
vii) Drive-The drive comprises a motor, V-belt and gearbox. Gearbox is couple to a shaft, which
has the drum.
2.2.4 The Power House
This subsection is concerned with the maintenance of the steam turbines both at the power
house and those turbines that run the heavy machinery at the extraction section and the steam
turbine running boiler 3B. The following things are inspected on the steam turbine while
monitoring its functions:

28. 21
a) Measuring the temperature of steam at the inlet and outlet of the team trap to find out if the
steam trap is functioning
b) Monitoring the condition of the turbine oil coolant by observing the temperature of the turbine
oil at the inlet and outlet of the cooler
c) Measuring the vibrations of the turbine to establish if it is within the recommended limits
Observing any cases of oil leaks and correcting the situation
Basically, to generate power we need a conductor and a magnetic field. The conductor is made
to rotate in (or cut) a magnetic field by either:
1) Rotating the field and stationing the conductor or
2) Rotating the conductor and stationing the magnetic field.
For the case at hand, several prime movers (turbine blades driven by dry steam) are used to
rotate the conductor as in 2 above.
Equipment used for electrical power generation
Two kinds of equipment similar in operation exit, namely:
i. Turbine and
ii. Diesel generators. Synonymously referred to as alternators.
Turbine alternators are five in number, namely: TA1, TA2, TA3, TA5 and TA6.Diesel alternators
are3; DA1, DA2 and DA3, which operate.
Several voltages are produced by these generators and later synchronized to form a larger
voltage. Power is generated at 3,300 volts (3.3KV) and later distributed in three phases to
supply a voltage of 415 Volts (after passing through a step down transformer) to motors and
control panels.
There exists a bus on the voltages are merged and inter-pass transformer that steps down 3.3
KV to 415V and vice versa between two control panels.
Power demand at the factory
The entire factory needs about 7MW.Fortunately, the powerhouse produces about 10MW,
which is excess. The remainder is used to serve the residential estates and sometimes supplied
to the KPLC national grid.
The leveler, heavy-duty knives and the shredder are among the highest consumers of power,
taking about 3MW cumulatively.
The consumer equipment determines the voltage and quantity of current to be used. A voltage
of 240V is supplied to the residential estates. The equipment used in these areas consumes a
current varying with the use. Therefore protection is done by use of circuit breakers and fuses,
rated at different respective currents.

29. 22
For proper utilization, power is tapped from the Main line (overhead) in an alternating way, a
phase at a time.
Some factors that keep the alternators in good condition are:
i. Good quality of steam
ii. Clear lubrication oil and
iii. Enough cooling water for bearings
2.3 THE BOILERS SECTION
The boiler section deals mainly with the process of raising the necessary steam required in the
firm for a number of purposes. The types of boilers used for this purpose are the baggase fired
water tube boilers. These boilers mainly utilize bagasse obtained from the cane crushing process
as their main source of fuel. In some instances this baggase is supplemented with crushed logs
of trees. The water used in these boilers is obtained from the nearby river Nzoia and pumped to
the factory.
The sugar plant boilers section contains a total of seven boilers, four of which are small and three
large boilers. These boilers are named from boiler 1-4A for the small boilers and 1-3B for the large
boilers.
2.4.1 Steam Generation
Steam generation is the process by which soft clean water is pumped through the boiler water
tubes (for a water tube boiler), which transfers heat from fire to the water, which vaporizes into
steam. This steam is then superheated and then passed under high pressure to prime movers
(turbines) and other process equipment (to provide energy).
2.4.2 Source of fuel for the boilers
The chief source of fuel is bagasse. The bagasse has (and indeed should have) a low
moisture content (usually 48-50%) for better combustion A high moisture fuel requires a slower
distribution into the furnace, for complete combustion (but will reduce amount of heat
produced), while that with low moisture require slightly lower distribution to give maximum
turbulence and accelerate combustion of volatiles released. Combustible constituents include:
Carbon, Hydrogen and Sulphur.
2.4.3. Use of the boilers
Steam generated from the boilers performs the following functions within the factory;
i. Run the steam turbines in the leveler, heavy duty knives, shredder hammers and the
dewatering mills in the extraction section.

30. 23
ii. Run the steam turbines at the power house to generate electricity used in the factory and
the company’s residential estates.
iii. The exhaust steam from the extraction section and power house is carried to the process
house to prepare sugar.
iv. Steam produced is also used for heating purposes within the factory, washing and driving
heavy machines like mill rollers, both leveler and cane knives and shredder.
2.4.4 Boiler types
Fire-tube (low pressure) boilers: In this type of boilers, the heating agent (fire/flames) pass
through the numerous tubes from the furnace and water surrounds the tube bank. They find
use where low-pressure steam is needed.
Water-tube (high pressure) boilers: These are the ones applied in this factory. Here, the water
passes through the tubes and the fire surrounds the tube bank. They are actually high-pressure
boilers suitable for the kind of applications in the factory like evaporation and power
generation.
2.4.5 Boiler feed water and its quality
Feed water source
Condensed steam from evaporators, heaters and pans’ calandrias is usually the source of feed
water. This water is clean but still requires some treatment of hardness, total dissolved oxygen
(TDS) and oxygen scavenging.
Usually the same amount of water is not gained; this is because of some losses due to steam
leakages, its use in centrifugals, pan steaming, soot blowing and other areas. Therefore vapour
is always condensed and additional make-up water added from the treatment plant.
Feed water treatment

31. 24
Figure 10: Water treatment flow diagram in Mumias Sugar Company
1 Alkalinity: Due to entrainment in the evaporators, vapour may contain some sugar traces in
the feed water. Sugar traces will decompose at high temperatures to form organic acids in the
boiler, hence destructive; causing corrosion if present in any quantity. Alkalinity is controlled
and maintained above 8.5.Sodium hydroxide (NaoH) is preferred to maintain a high alkalinity of
necessary boiler water.
2 Total dissolved oxygen (TDS): Conductivity indicates the total dissolved solids. These may
include; Ca, Mg, Al, Fe, Zn, Ca (HCO3
)2,
C12
H22
O11
, oxides and others. Calcium bicarbonate forms
the following products on disintegration:
Ca (HCO3
)2
CaCO3
+ CO2
+H2
O but, CO2
+H2
O H2
CO3
H2
CO3
is corrosive and therefore dangerous. Both intermittent and continuous blow downs are
employed to lower dissolved and suspended solids content, to prevent scaling and
entrainment.
3. Removal of oxygen: Oxygen is feared for its oxidizing power. If present in large quantities
then there is a risk of oxidizing the boiler tubes especially under high temperature conditions.
It’s scavenged by adding Sodium Sulphite.

32. 25
2NaSO3(S
) + O2(g)
2NaSO4(S)
3.5.2.4 Removal of calcium and hardness: This is removed by adding sodium phosphate.
2Na2
PO4
+ 2Ca
2+
Ca2
(PO4
)2
+ 2Na
+
Hardness should read zero at all times. Antifoams are usually used combined with sludge
conditioners.
2.4.6 Steam generation trends
It was observed that the temperature of the flue gases, which left the furnace, was in the
region of 350-380°c.This reduced to about 110°c after passing through the heat recovery
equipment (the economizer and air heater). This is a sign of good heat recovery. Further it was
noted that if exit temperature reduced to less than 100°c, condensation is likely to occur,
forming water that might combine with SO2
and SO3
to form H2
SO3
and H2
SO4
, damaging the
chimney and other parts at the exit. It was observed that, for the purposes of mass and energy
balancing, every given amount of water entering the boiler, the same (should) appear as steam.
2.4.7 Working principle of boiler
The basic working principle of boiler is very simple and easy to understand. The boiler is
essentially a closed vessel inside which water is stored. Fuel (bagasse) is bunt in a furnace and
hot gasses are produced. These hot gasses come in contact with water vessel where the heat of
these hot gases transfer to the water and consequently steam is produced in the boiler.
Figure 11: working principle of boiler

33. 26
2.4.8 Equipment and accessories of a modern boiler plant
I. Steam drum
Steam is generated in the steam drum. In order to avoid entrainment, it is provided with drum
internals- baffles, cyclone steam separators and steam scrubbers which channel the mixture,
separate the water and release dry steam at the top of the steam drum into the super
heaters.
II. Mud drum
Connected to the steam drum via pipe work.
III. Feed water tank and boiler feed pumps.
Steam is continuously withdrawn hence feed water must also be continuous. A reserve water
tank serves this purpose and feed water is pumped under pressure to the steam drum.
IV. Super heaters
Heat exchangers utilizing flue gas. Convert saturated steam from the drum into superheated
steam (dry steam) for use in the turbines. Tubes are of smaller diameters between two
headers, the degree of superheat depends on the heating surface of the super heater.
V. Economizers
It is a heat exchanger placed into path of flue gases leaving the boiler, through which feed
water is circulated between the feed pump and the boiler. It consists of tubes, generally fitted
with radial fins through which the water circulates. Tubes are arranged in groups, the water
passing from one tube to the next by means of 180 degrees bends.
VI. Air heater
Heat exchangers also utilizing energy from the flue gases. Heat air needed for bagasse
combustion. Commonly used is a tubular air heater in which the hot gasses pass through
ordinary chrome copper sheet tubes of about 57mm diameter and the air passes around
these tubes absorbing heat.
vii. Draught and fans
In order to maintain the temperature and rate of combusting, the required quantity of air
must pass through the furnace and over the fuel bed.
Types of draughts:
Natural-From the thermal energy released during combustion. It is created by the
chimney.
Forced-From a fan.
Categories of fans
a) Forced draught fan
Air blown through the grates and usually through the air heater. Permits the introduction of
air at atmospheric pressure into the combustion chamber. The amount of air needed for
combustion is controlled by a damper.
b) Induced draught fan

34. 27
Located at the base of the chimney sucks the gases from the boiler and expels it through the
chimney to the atmosphere.
c) Secondary air fan
Used when boilers are equipped with spreader stoker furnaces. They help to propel violently
the bagasse into the combustion chamber and give the necessary oxygen for immediate
combustion of a part of this bagasse while it is still in suspension.
viii. Spreader stoker furnace
Has no enclosing wall and is simply a flat space situated under the boiler tubes. The grates
made of cast iron can be fixed or of rocking type. They dump bagasse at regular intervals. As
bagasse enters the furnace, it is thrown and spread using forced draught and secondary air,
hence high combustion rate. The furnace also facilitates ash removal therefore it is clean to
operate.
VIII. De-aerator
It is a pressure vessel in which low pressure steam (exhaust steam) is used both as a
gas stripping medium and as a heating medium to raise the temperature of the water
to boiling. Work on counter current principle, with the incoming steam contacting the
heated water. To obtain efficient gas transfer, the incoming water must be sprayed.
The de-aerator eliminates both oxygen and carbon dioxide from the boiler water.
IX. Soot blower
Device utilizing high pressure steam jets to clear gas passes.
2.4.9 Mumias Sugar Company Boiler Plant Systems.
1. Conveyors System
The conveyors at boilers are Rubber and chain/slats conveyors
The rubber conveyors in the section are coded as B87B, K02, K07, K09, K15A and K15B while
Chain and slats conveyors are K03 and K12.
From the diagram, B87B and K09 feed K02. K02 feeds K12 and K03. K12 feeds furnace of boilers
1A, 2A, 3A, and 4A with the excess being fed on K15A. K03 feeds the furnace of boilers 1B, 2B and
3B with the excess being fed on K15B. K15A also feeds K15B. K15B feeds K05 which has a plough.
The plough distributes the bagasse in the bagasse store or directly on the bagasse rake, K17. The
bagasse rake feeds K07 which in turn feeds K09.
B87B carries bagasse from the de watering mills while K09 carries bagasse from the bagasse
store. The bagasse from the store supplements the bagasse from the mills.
The following is a schematic diagram of the bagasse system conveyors.

35. 28
Figure 12: Bagasse system conveyors
Routine maintenance and daily checks
Main Components of the Conveyor
i) Head drum
The boiler thus can be subdivided into the following systems;
2. Steam line system
The steam line is composed of condensate water, its treatment and movement to the boiler,
heating it until it forms steam that is further superheated and then collected at the steam
receiver.
Condensate from the condensate tanks is pumped using multistage centrifugal pumps to the
overhead tank and then pumped further to the steam drum of the boiler.
From the steam drum the condensate fills the boiler tubes and the mud drum.

36. 29
The steam drum located above the furnace is filled halfway with the condensate and the other
portion left as steam space in which the steam formed is collected.
The condensate is usually at a temperature of over 60 degrees Celsius so that as it enters the
boiler it is heated shortly and gains the latent heat of vaporization to form steam. To achieve this
even faster the condensate passes through the economizer tubes where it is preheated on its
way to the steam drum.
The boiler tubes are also categorized in various ways such as main bank tubes, down comers, wall
tubes and the super heater tubes. All other tubes are filled with condensate apart from the super
heater tubes that carry wet steam as it continues being heated further to achieve the required
superheat state.
From the boiler superheated steam is carried via lagged steam pipes to the steam receiver where
it is stored and its pressure monitored and controlled before being ferried to the various turbines
for use.
The steam is supplied to the turbines in the extraction section where the steam runs the steam
turbines in the leveler, heavy duty machines, the shredder and the dewatering mill turbines.
From these turbines stem having lost some energy is transported to the process house where it
is used in the primary heaters, secondary heaters, pre heaters, evaporators and in the drying of
the processed sugar.
Steam is also ferried to the power house where it is used to run the turbines hence generate
electrical power used by the company.
From the process house the condensate is pumped to the condensate tank waiting being fed
back to the boiler for another cycle.
3. Fuel system
The main fuel used is baggase obtained from crushing of sugarcane at the extraction section and
at times is supplemented by crushed wood. This fuel is used for heating in the boiler furnace so
as to generate the required steam.
Bagasse is transported by a system of conveyors from the dewatering mills and the bagasse store
to the various boilers. The conveyors here used are belt conveyors made of pregnated rubber,
rake conveyors, and slat conveyors made of steel that are used to feed baggase to the various
boilers.
These conveyors are run by motors that are linked to reduction gear boxes that provide the high
torque necessary for running these conveyors as most of them are heavy.
At the feeders there are feeder drums also run by motors linked to reduction gear boxes that
regulate the amount of bagasse being fed to the boiler furnace.
4. Air system
Each boiler is served by 3 fans namely forced draught (F.D) fan, secondary air (S.A) fan and the
induced draught (I.D) fan.

37. 30
The FD fan supplies the air necessary to support combustion in the boiler furnace and this air
passes through the holes provided on the ash grates to the furnace.
The SA fan provides secondary air into the furnace which performs two functions; since it is
located below the feeder inlets to the furnace the valves are opened periodically and this air is
pumped to the furnace to evenly distribute bagasse to the furnace so that it does not heap at
one position, in addition to this secondary air supports combustion at the upper parts of the
furnace to ensure that bagasse is burnt completely.
The ID fan sucks the flue gases and sand formed after combustion and leads them out through
the chimney.
5. Flue gas / Ash collecting system
The ash formed is eliminated through various ways from the furnace;
Firstly the ID fan sucks the flue gases and drives them out through the chimney.
The ash grates are made in such a way that they are connected to a fire square bar that is
controlled by a lever that is in turn operated by a double acting piston cylinder (pneumatic
system) which operates the lever and the grates open to allow the ash formed to drop in the
submerged ash conveyers containing water that cools the ash before it is disposed off.
The ash that is not carried away by the ID fan is allowed to collect in the hopper tanks then
discarded.
6. Hydraulic / pneumatic system
This system ensures that the boiler operates within the required pressures. The pneumatic
cylinders for instance control the opening and closing of ash grates to allow for discard of ash.
The system is made of double acting piston which moves the lever back and forth thereby
controlling the opening and closing of the grates.
7. Electrical system
The electrical system of the boiler section mainly consists of motors which drive the reduction
gear boxes that run the conveyors and the feeder drums. The motors also run the various pumps
used to pump the condensate to the boiler.
These motors are linked to the gear boxes via spur or helical gears.
The transfer of torque from the gear box to the drive shafts is done in the following ways;
If the shafts are in the same line then a flange coupling is used.
If the shafts are parallel to each other then sprockets are used to transfer the torque.
If the shafts are perpendicular to each other a bevel gear is used to transfer the torque.

38. 31
2.5 PROCESS HOUSE OPERATIONS
The section deals with processing of juice from the Extraction Plant to produce the market
sugar and molasses. Some of the processes of such includes; Weighing, Heating, Clarification,
Evaporation, Sulphitation, Pan Boiling, Crystallizing, Centrifugal Separation, Drying and
eventually Packaging
2.5.1 Juice Treatment
The major components at this sub-section include Mixed Juice Scale, Mixed Juice Tank, Primary
Heaters Secondary Heaters, Flash Tank, Clarifiers, Pre Heater, Evaporators, Lime Tank, Caustic
Tank, Sulphitor, Condensers, Condensate Tank and The Water Treatment Plant
Figure 13 : Flow diagram of juice treatment and equipment used
RAW JUICE SCALE
Raw juice from the Draft Juice Pumps to the process house is automatically weighed before the
process house operations. The scale weighs 5.2 tons of juice every batch as the reading is
recorded on a counter the prince of operation being load cell. The scale is periodically checked
for trapped matter.
MIXED JUICE TANK
After weighing the juice drops by gravity to the Mixed Juice Tank which acts as a temporary
storage for juice before it’s taken to the heaters. The tank also receives sugar remelts from the
remelt tanks, juice spills from sump pits and return juice from treated and raw juice tanks in
cases of overflow

39. 32
FLASH TANK
This is cylindrical tank located just above and ahead of the clarifier with a flue open to the
atmosphere. The juice from the heaters discharges tangentially in to the tank; since the juice
has been brought to about 105 ⁰C; it partially flashes in to vapour when discharged into this
vessel at atmospheric pressure. This flashing removes from the suspended particles the air
bubbles attached to them which if not removed will prevent particles of baggase from settling
during the clarification process.
JUICE CLARIFIERS
Clarifiers are used to separate out the solids suspended in the cane juice. These solids originate
from sand adhering to the cane stalks as well as from material inherent in the cane stalk. The
separation takes place by allowing the solid particles to settle out onto a tray. The solids are
swept from the tray into a mud compartment, from which it is pumped to the diffuser.
The company uses SRI Type Clarifiers. The SRI clarifier is a single tray clarifier characterized by
short juice retention times (usually 40 minutes or less).
The juice to be settled is fed uniformly and continuously and which is large enough to reduce
the velocity of the flow and the circulation of the juice to such a low value that it does not
prevent settling from taking place. The clear juice obtained is withdrawn from the upper part of
the clarifier in an equally continuous and uniform manner as also the mud from the lower
portion.
The benefits of the single tray short retention clarifier are:
 Short retention time, hence less sucrose destruction, and colour formation
 Higher throughput capacity
 Lower capital cost
 Lower maintenance cost
 Easy to liquidate and hence regular cleaning is possible
Clarifier Maintenance
 Check the Scraper drive for proper operation
 Check Gearbox oil for good operational level and quality, if low; top up and if the quality
poor; consider changing
 Check the Chain drive if running properly
 Mud pumps inspected
2.5.2 Evaporation
Introduction to evaporation
Juice obtained from cane is too dilute for the process of crystallization, by which sugar is
extracted. Consequently, the juice has to be concentrated in evaporators.

40. 33
Concentration of juice should not go too far or else crystals will come out at>70’ brix. Usually a
concentration of 60-65’ brix is not exceeded, so that the false grains may be dissolved when the
syrup is fed into the vacuum pans.
1. EVAPORATOR
The evaporation process description
Clear juice (from preheaters) is taken to evaporators at a temperature of about 103’c.The
heating agent is steam (exhaust steam from the power generation turbines at a controlled
temperature). Juice passes in the tube side of the heat exchange equipment (evaporator), while
steam passes at the shell side, where the steam heats the juice externally.
It should be noted that the main aim of evaporation is to boil off water from clear juice;
increasing its brix concentration from about 11 percent to about sixty five percent.
For every effect, vapour is withdrawn and designated as either vapour 1(for the 1
st
evaporator),
vapour 2 for the 2
nd
e.t.c., depending on which evaporator is involved in a given stream. Vapour
1(V1) is used to heat the 2
nd
evaporator and some withdrawn to heat vacuum pan boilers (for
crystallization), and the secondary heaters when necessary.V2 heats the third evaporator for a
given stream, some taken to heat the primary heaters and those heating diffuser juice.
Vapour withdrawn from a preceding evaporator is use for the next evaporator consecutively
until finally a vacuum created at the 4th evaporator through a barometric condenser withdraws
it.
Juice from the evaporators is called “raw syrup” and is held at raw syrup extraction tanks
before getting pumped to the raw syrup boxes. Condensate from the 1
st
&2
nd
evaporators of
each stream is termed pure condensate; since it is supposed to be free of sugar traces, and is
taken for steam generation at the boiler.
Condensate from the 3
rd
& 4
th
evaporators is called sweet water condensate and is stored in
sweet water tanks from where it is used for various industrial tasks like imbibitions in the
diffuser, thinning at pans and other cleaning purposes, to the sumps.
Evaporator main controls
a. Amount of steam admitted to the 1
st
evaporator (effect)
b. Level of liquor in the 1
st
effect
c. Brix of liquor (syrup) leaving the last effect
d. Proper bleeding of incondensable gases

41. 34
e. Temperature on each evaporator (effect)
f. Vacuum level on each evaporator
Steam admitted in the 1
st
effect provides the driving force for the whole apparatus.
Consequently it I adjusted according to the amount of evaporation required. If we have more
juice to evaporate or want more concentrated syrup, we admit more steam.
Scales
These are deposits formed inside the tubes, they originate from materials in suspension in juice
as a result of poor clarification or non sugars in solution which become insoluble as the as the
juice becomes concentrated
The scale majorly consist of; calcium salts, metallic oxides and silica
The scales deposits more rapidly when the evaporation rate is sluggish hence the need to
improve the speed of circulation or the state of agitation of the liquid and therefore normally
much thicker at the bottom part of the tubes where the juice is relatively stagnant
Descaling of the evaporators
Mechanical cleaning is effected with the aid of electric descalers. These consist of electric
motors which may be plugged in to power points close to the evaporators; the motor has a
flexible shaft enclosed in a protective sheath and terminating in a tool of serrated rollers which
drives at high speed. The rollers are loose on their axes so that the centrifugal force presses
them against the walls of the tube hence can be able to clean tubes of slightly different
diameters. The tool is passed from top to bottom manually in repeated manner
The success of the cleaning is dependent on the following factors:
I. The sharpness of the cutters which may get blunt rather frequently and need to be replaced
II. The stamina of the operator handling the flexible cables and moving them from tube to tube
III. The sureness of inserting the tool to the bottom limit of the tubes
IV. The experience of the labourer used
Maintenance of Evaporators
 Caustic cleaning of the heat exchange tubes during shutdowns followed by inspection of
heating surface and mechanical cleaning if and when required
 Checking of the valves on all the suction and discharge line for proper operation
 Hydraulic testing of the callandria at pressure 1.5 times above the normal operating
pressure for any leakages with eventual sealing
 Plugging all the leaking tubes-this will depend on the nature of the tube leak
 Replacing damaged tubes during long stoppages
 Manhole inspected
 Condenser inspected and cleaned
 Inspection of the condenser nozzles and manhole gaskets

42. 35
2. CONDENSATE TANKS
Condensate Tanks are used for temporary reception of condensate from heaters, evaporators
and pans with the subsequent use and transfer depending on the purity of the condensate.
3. SULPHITOR
Syrup Sulphitor are important in sugar process to maintain the quality of syrup to feed the Pan.
They appear totally indispensable in the production of white sugar in all the sugar industries,
sulphur being the main bleaching agent in the production of white sugar
Maintenance
 Scrubbers opened for cleaning
 SO₂ line flushed with water to remove deposits
 SO₂ injector nozzle inspected for blockage
 SO₂ cooling column inspected for leaks
4. PUMPS
Pumps are used to deliver material to various stages in the process house unless where the use
of gravity is necessary. Among the numerous pumps used in the process are tabulated as
below.
Table 3 : Pumps used in the process house
CATEGORY TYPE DUTY
1st stage weighed juice
pump
Big Warman-centrifugal Pumps the weighed juice to the
primary heaters.
2nd stage weighed juice
pump
Big Warman-centrifugal Pumps the juice from the primary
to the secondary.
Clear juice pump Big Warman-centrifugal Pump clarified juice from the
clarifier to the pre-heaters.
A syrup, B and C Syrup Small Warman-Centrifugal Pump syrup from the last effect
evaporators to the syrup boxes.
Treated syrup and Syrup
Recirculation pumps
Small Warman-Centrifugal Pumps treated syrup to treated
syrup boxes and mixing of syrup
respectively
Injection pumps Guild Pump-Multistage
Centrifugal
Pumps injection water used in the
condensers to the process house
Flocculant dosing pumps Mono pumps rotor type Pump the flocculant into the
clarifier
Dorco pumps Diaphragm pump Pump the mud from the clarifier
into the mud tanks.

43. 36
Mud pumps Centrifugal open impeller
type
Pump the mud in the tanks back to
the diffuser.
A sweet, C sweet, A1/B1
pure condensate, A2/B2
second effect condensate
100/40 SSP pump-
centrifugal
Pump the sweet condensate to the
overhead tanks
Milk of lime pump Warman type-centrifugal Pumps lime to the mixed juice line.
Imbibition booster SNB 6 pump/ Small
Warman-centrifugal
Pump injection water to the
diffuser
Caustic pump SNB 6 centrifugal type Pumps caustic soda to the juice
line.
Treated syrup no. 2 SNB 6 -centrifugal Pumps sulphated syrup from the
tank to the treated syrup boxes.
A Molasses Pump Magmaflo 150 Pumps A molasses from the A
station to the molasses tank

44. 37
2.3.4 Sugar House Section
Figure 14: Flow diagram of the pan boiling process
1. PANS
A pan is a single effect evaporator in which sugar boiling occurs under vacuum. There are two
types of pans: batch and continuous pan. A batch pan is a vertical cylindrical vessel consisting of
a calandria and a vapour space. During boiling, a set quantity of seed is introduced and syrup or
molasses is fed until the pan is full. Once the boiling cycle is complete, the product (massecuite)
is discharged and another boiling cycle is started. The basic features of a batch pan are illustrated
below.
There are two common types of feed distribution: the star feeder and ring feeder. In the star
feeder, the feed pipe passes above the calandria into the down take and is connected to four

45. 38
pipes constructed perpendicularly to each other. The feed holes face downwards. Mumias
Sugar Company uses the ring feeder system which consists of a feed pipe that enters through
the bottom of the pan and joins a ring, which encircles the bottom of the pan, directly under
the calandria.
The calandria is designed with a wide centre well. The object of this well is to allow massecuite,
which has already risen above the tubes in the liquor belt to go down again via the centre well
to the conical bottom and be able to pass up the tubes again. This encourages circulation.
A hydraulic controlled valve is situated at the centre of the conical bottom to discharge the
massecuite into the crystallizer. A cut-over line is connected to the bottom of all the pans and is
provided with a valve on each pan. This enables cutting of massecuite from one pan to another.
2. CVP (CONTINUOUS VACUUM PAN)
A continuous pan is a horizontal vessel with a number of compartments or cells (usually 12)
connected in series. The seed is continuously fed to the first compartment and flows through
each compartment until it reaches the last compartment. Syrup or molasses is fed to each
compartment and the product (massecuite) is continuously withdrawn from the last
compartment.
The continuous pan is equipped with four systems of control designed to maintain at relatively
constant level.
 Steam pressure in the tube
 Vacuum in the pan
 Pressure of the agitating steam
 massecuite level in the pan
The condenser for CVP is regularly cleaned during stoppages and the nozzle boxes inspected for
any blockage
3. CONDENSER
These are enclosed vessels used to create vacuum in the Multiple Effect Evaporators and the
Pans. Cold water is pumped into this vessel to ensure condensation of the vapour coming from
the pans and the evaporators. The condenser is placed at such a height that the water after
serving to condense the vapour can flow out by gravity together with the condensed vapour.
The discharge column (barometric leg; also acts as a seal set at 10.3M) extends at the bottom
dipping to a well open to the atmosphere
Maintenance
The man hole are normally opened and the nozzles inspected for blockage during and between
stoppages

46. 39
4. STRIKE RECEIVERS
This is an ordinary steel vessel of u shaped cross-section fitted with a stirrer permitting it to
maintain the mass in a slow and continuous motion. The massecuite when discharged from the
pan is at high super saturation, if its allowed to stand the sugar still contained in the mother
liquor will continue to be deposited as crystals but this massecuite is very dense and the
mother liquor very viscous . crystallization will soon cease if the massecuite is left undisturbed
because the layer of the mother liquor surrounding the crystals will rapidly be exhausted and
the viscosity of the mass will prevent the more distant molecules from circulating and coming
into contact with the crystals, therefore it must constantly be kept in motion to in order to
change the relative position of the particles of the mother liquor and of the crystals.
The agitator is run at low speed through worm and wheel connection
The drive and the gearbox should always be checked for smooth run i.e. for contamination of
lube, sufficient lube and unusual noise.
5. CRYSTALLIZERS
Vertical Cooling Crystallizer
Further crystallization can be achieved by cooling the massecuite in order to raise the super-
saturation of the mother liquor. Therefore, low purity C massecuite is pumped to a vertical
crystallizer where further crystallization takes place thus improving exhaustion as it supports
crystal growth through cooling. The crystallizer is equipped with cold-water coils and a stirrer
rotating at 0.25 rpm. Retention time is about 30-40 hrs with the rate of cooling being 1oC / hr.
6. “C” MASSECUITE REHEATER
C-massecuite after being cooled in the Vertical Cooling Crystallizer is reheated to about 50oC
before curing. This lowers the viscosity and facilitates separation at the fugals. The Reheater is a
closed vessel containing several bank of finned steel tubes stacked together over which the
massecuite flows. Hot water is circulated in the tubes, and heated in a clarifier using exhaust
steam as the heating medium. The flow of the massecuite and water are counter current. The
massecuite flows by gravity from the Vertical Cooling Crystallizer through to the Reheater
finally to the C-fugal Header
7. CENTRIFUGALS
Once the mother liquor has been exhausted to the practical limit for the strike concerned it is
separated by use of centrifuges in order to obtain the sugar in the commercial form.
A centrifugal machine consists of a spindle with a perforated steel basket connected to it. The
spindle and the basket are driven by an electric motor and rotated inside housing. A screen is
inserted into the inside of the basket, alongside its inner circumference. This screen keeps back

47. 40
the crystals but the mother liquor is allowed to pass through holes or slots and flows down the
housing walls.
There are two types of centrifugals:
1. Batch centrifugals-for A curing
2. Continuous centrifugals-for B/C curing
1. Batch centrifuges
Consists of cylindrical basket designed to receive the massecuite to be treated and carried on a
vertical shaft which is driven from its upper end by a motor. The basket has numerous holes to
let the molasses escape and is provided with circumferential hoops to withstand the centrifugal
force.
The basket is open at the top to allow massecuite to be fed in to it and bottom opening to allow
the sugar to be discharged when the machine is stopped. When the machine is running the
discharge is normally closed
The perforated basket is furnished with a backing screen on the inside which is a coarse woven
stainless steel screen (8 meshes). This screen is covered by another stainless steel screen (5
meshes). On the inside is a perforated sheet of stainless steel designed to retain crystals. The
slots on this sheet are diverging in such a way that they get wider from inside to the outside.
This prevents clogging of the screen.
The massecuite is charged from the top and builds up against the screen until a wall of
massecuite of a certain thickness is formed. The centrifugal rotates rather slowly at this stage;
to allow the massecuite to spread evenly over the surface of the screen, thus preventing
imbalance.
When the basket is loaded with massecuite, the machine accelerates to high speed (1000 rpm)
and the molasses will be separated, water sprayed on the inside of the sugar wall to wash the
molasses residue from the crystals. Spinning continues for a while to remove as much of the
wash-water as possible. The basket is then slowed down, the discharge valve opens and sugar is
removed by a plough, which is lowered into the basket. The discharge valve closes and the cycle
is repeated.
2. Continuous Centrifugals
It is driven from below and consists of a conical basket with a screen fitted on the inner surface
with a backing screen in between. Massecuite is fed continuously from the top and it is
accelerated in a cylindrical cup. Centrifugal force makes it slide up the cone in a layer of ever
decreasing thickness
Molasses escape through the perforations of the screen and are caught on the walls of the
cone. Holes in this wall allow the molasses to drain into the molasses compartment. The
crystals are kept back by the moving screen and move up until they reach the rim and are
discharged into an outer stationary housing, where they drop down into a screw conveyor. The

48. 41
high force with which the crystals contact the wall causes damage to the crystals. Thus,
continuous fugals are not used for A-sugar.
In cases where B-sugar is used as seed for A-strike, the outer casing is made of bigger diameter
to reduce the number of crystals damaged.
Maintenance
 Check the sugar and molasses buckets for wear and replace if need be.
 Replace the screens
 Check the shaft bearing and rectify
 Check the plough (for high grade centrifugals) for wear or straightness and rectify
accordingly
 Inspect the sugar screw conveyor for wear and replace or repair
 Replace and/or repair all the pipes to and from the centrifugal that are worn out or torn.
 Check vibration dampers and replace if worn.
 Check vee-belts, pulley and replace if worn.
8. SCREW CONVEYORS
Used to carry wet A sugar from the centrifuges to the bucket elevator. Used also between the
vibrating screen and the bridge conveyor and for mixing vitamin A and sugar
Maintenance
 gear box oil checked regularly
 greasing and oiling of the bearings
 shaft inspected for any misalignment
 scrubbing of the caked sugar
 cleaned by flashing with hot water
 check for wear on the scroll/trough
9. SUGAR DRYING
Sugar discharged from the A-centrifugal is wet and hot and has to be dried before storage and
packing. The sugar is dried to reduce microbial activity and to prevent caking. A bucket elevator
transports the sugar from the conveyor up to the sugar drier.
A sugar drier consists of a drum through which the sugar passes in counter current with hot air.
The drum is slightly inclined to discharge and it’s supported by rollers. The inside of the drum is
provided with longitudinal louvers, which pick up the sugar and drop it as a curtain across the
full diameter of the drum. The hot air drawn through the drum provides enough heat to
evaporate off the water (apart from the heat carried by the sugar itself when it leaves the
centrifugals after steaming).

49. 42
Air from the atmosphere is heated by passing it through tubes of a heat exchanger with steam
(60 PSI) as a heating medium. The air is heated to about 65oC and drawn by a fan through the
drum passing a wet dust catcher to remove the dust particle
Drier maintenance
 Thorough cleaning of the drier is done. Sugar that has dried on the louvers is removed
and kept in bags for remelting.
 Clean the air filters
 Check the belts and pulley drives for the fan and the drier for wear
 The screws are inspected for wear and changed if need be
 Inspect the bucket elevator drives for wear and rectify accordingly
 Replace worn out belts on the belt pulleys drives.
 Check support for wear and alignment and lubrication.
 Service drive gearbox as required.
 Check sealing ring and replace if worn.
10. VIBRATING SCREEN
Used to sieve the dried sugar of any caked sugar particles and any other non-sugar objects in
the sugar
Maintenance
 Cleaning for stuck sugar crystals
 Check for loose bolts and tighten
 Check the motors for vibration
 Check the motors foundation
2.5.4. Packaging Plant
The company use Raumak packaging machines from Brazil. There are 11 packing lines at the
sugar store. The machines are form, fill and seal type and pack different units (500g, 1kg, and
2kg) depending on the market demand.

50. 43
Figure 15: Flow Diagram of Sugar Bagging, Packaging and Warehousing
Components and the functions
Clamp-brake-controls the movement of the package
Vertical weld- seal weld the vertical side of the packaging
Vertical cooler-cool the vertical weld after actuating
Clamp assay-holds the package making it possible to cut, weld and cool the weld, around are
moulded the weld bar assay, for horizontal and vertical top and bottom welds, the cutter and
the horizontal cooling canals
Horizontal weld- seals the top and bottom of the package
Horizontal cooling- cool the welds on the package after the weld is done
Shaper- forms the flat bottom or siphon of the packaging before the vertical weld is applied
Elevator- lifts the packaging to form the flat bottom and applies the horizontal weld
Expulser- cylinder which push the finished packaging to the clamp assay
Sorter- organize the arriving package for chute
Catcher- which guards the preset quantity of packages from sorter, when quantity checks,
opens gate and packages enter packer on the clamp assay.
Moving rack- transport belt which moves the packages from the interconnecting belt to the
identifier
Collecting rack- a belt which moves the package from the packer to the moving rack

51. 44
These machines have several maintenance procedures that are followed to eliminate the
stoppages on them. The following are the procedures that are usually carried out at the sugar
store.
 The volumetric head (filler head) is usually serviced by cleaning the cups and servicing
the bearings.
 The clearance on the shoulder of the forming tube is usually regularly adjusted
 The film transport belts and the wear skips are replaced when they get worn out or torn
 The Teflon on the vertical and the horizontal jaws that are usually used to insulate the
shoulder are replaced on a regular basis.
 Jaws alignment is usually done on the sealing jaws
 The seals on the pneumatic cylinders are also replaced when they wear out.
 The printer nozzles have a problem of blocking up and are always cleaned whenever
they block up.
Routine maintenance carried out on sugar store equipment
Packaging machines
 Overhaul volumetric head and clean all parts.
 Service volumetric head filler bearings and thrust shaft bearings.
 Service volumetric head adjustment chain.
 Clean shoulder and tube. Replace wears tips and Teflon tapes.
 Clean film path including all film feed rollers.
 Check the condition of film transport belts and replace if worn out. Align and tension
appropriately.
 Clean horizontal jaws sealing surfaces and the knife grooves.
 Check jaw alignment and adjust appropriately.
 Adjust volumetric head proximity sensor to ensure correct cup stop position.
Baling Machines
 Rectify all compressed air leakages identified earlier.
 Check all conveyors for wear and replace
 Check and service ball bearing for bottom horizontal conveyors.
 Check the condition of linear bearings for baler positioning boxes.
 Fasten all loose parts.
Regular maintenance checks on the packaging machines
 Checking moving parts for any interference
 Maintaining cleanliness of the machine
 Checking belts for proper tension

52. 45
 Checking oil level in the gearboxes
 Grease moving parts such as bearings, moving shafts, and chains
 Checking all the greasing points
2.5.5 Air Compressors
Provides compressed air used the entire factory operations, some of which includes; control
valves, packaging house-multi bags and the multi bailers, pneumatic controls and flocculants
mixing.
Maintenance Tips
 Inspection of the air filters
 Checking the compressed air line for any leakages.
 Checking the oil levels and refilling if necessary.
 Minor service done after 2000hrs
 Major service done after 4000hrs
Major maintenance is done by the suppliers which include;
 air filter replacement
 oil filter replacement,
 changing of oil
 Changing the drier elements.

53. 46
CHAPTER THREE
This indicates some of the identified problem and some available solutions. It also has the
recommendations and conclusion.
3.1 Some of the indentified problems and some remedies
3.1.1 The nature of frequent break downs experienced in cane preparation process
iii) knives coming off
When the knives encounters either a metallic object say arms of cane kicker, slat that has
come off, it is bound to break off. The tramp iron magnet arrests the knives that have
come off. If many knives have come off, the plant has to be stopped to replace them. A
hard rock in cane can also result in this breakdown.
iv) Worn out knives.
This happens especially during rainy seasons. Sand particles come with cane resulting in
severe wear due to abrasion. The preparation of cane becomes poor hence necessitating
stoppage and replacing the knives
These reduce the cane to smaller pieces exposing cells for subsequent extraction at the
diffuser. This system consists of a steam turbine driving the shaft containing knives. The unit
has more knives than the leveler and tends to cover the entire surface of the carrier.
3.1.2 The major problems experienced in boiler section are;
1. Leaks
Heat exchangers on boilers leak because the heat exchanger is;
Rust- Rust is a result of oxygen and water attacking the metal. Rust acts more quickly at higher
temperatures, so the environment in a heat exchanger is hostile.
Cracks -Cracks result from the thermal stresses on the heat exchanger over a number of years.
Cracks may also be caused by a manufacturing defect.
More Cracks- Cracks may also develop from metal fatigue (perhaps because of overheating,
sometimes resulting from not enough water in the boiler, or failure to pump the water through
the boiler).
Remedy to the problem
a. A leaking heat exchanger typically has to be replaced. Usually you replace the whole boiler
when you have to replace the heat exchanger. There are some exceptions, but for the
most part, it’s safe to say a new boiler is needed when a heat exchanger leaks.

54. 47
b. Regular checking should be done to ensure that there is no leaking and if there is a need
to replace the worn out one it should be done with immediate effect since leaking reduces
boiler efficiency, increases the heating costs, and may clog the exhaust gas passages,
leading to life-threatening spillage of exhaust gases into the home.
2. Rust
Rust is often caused by condensation from the exhaust products. It’s a common cause of
corrosion and early failure of heat exchangers, particularly on modern boilers that are
substantially oversized.
Damp Environment Rust may also result from a damp environment that a boiler may find itself
in such as a chronically wet basement or crawl space.
Chemicals Common household chemicals can rust furnace or boiler heat exchangers quickly.
One side of the boiler is always exposed to water and consequently may rust over time.
One cause of rusting heat exchangers is the poor practice of draining the water
Oxygen Causes Rust The reality is that the same water should remain in the boiler year after
year.
Remedy to the problem
a. The steam pipes and the boiler should not be laid on a place where there is damp of
water that may support rusting.
b. During drainage, oxygen should not be added into fresh water but to keep the same
water in the system year after year to minimize rust in heat exchanger, the pipes and
radiators.
c. Corrosive household chemicals should be stored near the boiler.
d. Heat exchangers are prone to corrosion and build-up of deposits between the fins
(fire side) they also require good water flow through the exchanger to keep from
overheating (leading to premature failure).
3. Clogged
This can result in reduced efficiency of the heating system. A soot buildup on the heat exchanger,
for example, restricts the heat transfer, resulting in more heat going straight up the chimney.
It can overheat the heat exchanger if the exhaust flow across the heat exchanger is restricted.
In severe cases, it can lead to spillage of exhaust products back into the house through the burner.
With a mirror and flashlight, look for black, sooty deposits on the heat exchanger.
These should not be seen at all on gas burners, and, although some soot can be expected on an
oil burner, watch for measurably thick buildups.
Remedy to the problem
a. Regular maintenance (cleaning) should be done. Where you have identified a partially
clogged or heavily sooted heat exchanger, you’re probably looking at a maintenance

55. 48
item rather than a replacement item. This is a far less serious condition in most cases
than a leak or severe rusting of a heat exchanger.
b. Check for spillage of combustion gases as you would on any burner. One cause may
be a restricted heat exchanger passage.
2.1.3 Frequent problems encountered with the pumps and some of their remedies.
1. Leakage from the stuffing box
 Check the total system head: either higher or lower than the design head.
 Check for shaft misalignment due to worn bearing, or bent shaft.
 Check whether the impeller is out of balance resulting to vibrations.
 Ensure that the gland packing is installed properly.
 Check the shaft and the sleeve for wear at the packing.
2. Vibration and noise
 Ensure intake pipe or pump is filled with liquid
 Check the suction lift to ensure that’s not too high
 Ensure that the suction line is sufficiently submerged, not blocked and that the foot
valve is of the right size
 Ensure that the pump is not operating at very low capacity
 Check for misalignment, rigidity of the foundation, bent shaft worn bearing,
damaged or imbalanced impeller or foreign matter in the impeller
 Ensure that right amount and quality of lubricant in the bearing housing. Check for
dirt getting into the bearings.
 Check the foundation bolts if tight
3. Excessive horse power consumption
 Ensure the direction of rotation is right, the speed is not too high and the total head
of the system is not lower or higher than the design head,
 Check the viscosity and the specific gravity of the liquid to ensure that they
correspond with the design values.
 Ensure no misalignment, bent shaft and rubbing of rotating parts against stationary
parts.
 Ensure that the right packing is installed properly and that the gland is not too tight.
4. Overheating or seizure of the pump
 Ensure that the pump is primed and existence of sufficient margin between intake
pressure and vapour pressure
 Ensure proper pipe installation and right liquid viscosity

56. 49
 Check bearings for wear, misalignment and also ensure that no parts are rubbing
against each other
 Check for excessive thrust caused by mechanical failure inside the pump
 Ensure that right amount and quality of lubricant in the bearing housing.
5. Packing has short life
 Check for misalignment
 Ensure that the foundation is rigid
 Check bearings for wear
 Ensure packing is properly installed and the shaft and its sleeve not worn
 Ensure that the gland is not too tight, no grit or dirt in the sealing
 Check for worn bearing, impeller imbalance (causing vibration) and misalignment.
 Excessive clearance at the bottom of the stuffing box forcing the packing into the
impeller,
6. Hopper overflows
7. Discharge failure
8. Reduced discharge delivery
9. Insufficient pressure
10. Loss of prime.
Likely causes of pump failures
 Poor operation when a valve has not been opened, this causes the pump to overheat,
the operator may put off the pump and forget to drain any material inside.
 Carelessness on not checking on the lubrication levels in the pump.
 Foreign bodies left inside the pump when packing.
 Poor installations due to poor alignments.
3.1.4 Frequent problems experienced on the packaging machines
 Welding bar not moving forward or return
 Clamp assay failing to open and close
Closing weld not cutting or clamping
 Weld failing to cool
 Variation in the length of the package
 Welding separating after packaging is finished
 Heating coil failing to heat up
 Weld on the top and bottom failing to actuate

57. 50
 Weld failing to function completely
3.2 RECOMMENDATION
To The Mumias Sugar Company:
 Install variable speed drives at some of the major pump stations e.g. 1st and 2nd stage
to regulate juice flow; use of control valves could lead to build up pressure with
eventual leakage of the pumps (inverters already purchased).
 Process house operations to be synchronized with the extraction plant to reduce
wastages.
 All stakeholders to be involved in the process house project for better judgment in site
planning and ergonometric consideration.
 Operation team to put more emphasis in implementing changeover of pumps in cases of
redundancy to avoid running pumps to failure.
 Research on the more durable gland packing materials for the process house pumps-
have changed from K10 to K3222
 Coding/Lagging of all the pipes in the process house.
From the period of Industrial attachment I had I would wish to give the following
recommendations that I think if implemented would make this exercise have minimal challenges
to both students and even the lecturers. These recommendations can further be adopted by MSC
as they also touch the side of company’s relationship with the attaches. On part of MSC I do
recommend that;
i. The number of days they devote to serve attachees during application be increased to
two days per week say Monday and Thursday from their routine Thursday as this makes
students waste a lot of time and resources travelling to the company incase their service
was not to completion.
ii. The company should at least advance some token of appreciation to the attachees so as
to motivate them to work even harder, these includes things such as accommodation and
lunch vouchers. This will make the attachees to have more strength of learning and at the
end get more experience as related to their career.
On the part of the university the following are recommended for adoption;
i. Send the students to the firms after thorough consultation with the firms. This will at least
reduce the hustle the students normally have during the process of getting attached.
ii. Organize for assessments in time.