CHAPTER 1 · 2018-07-12 · JIMMA UNIVERSITY (JIT) SCHOOL Of MECHANICAL ENGINEERING 2015GC FINAL...

JIMMA UNIVERSITY (JIT) SCHOOL Of MECHANICAL ENGINEERING 2015GC

FINAL INDUSTRIAL INTERNSHIP REPORT [Wonji/Shoa Sugar Factory] 1

CHAPTER 1

1. INTODUCTION

1.1 Location and Foundation of WSSF

Wonji/shoa sugar factory is located at southeast of the country and far from Addis Ababa

110km at Adama-Asalla road. This company is founded by kaizen in 2011. But wonji/shoa

sugar factory produce sugar at the wonji town that is the upper reach of Awash Ethiopia

112km southeast of Addis Ababa after taking the land of nomads in 1951, Ethiopia

government granted a concession of 5,000 hectares. For increasing demand of sugar in

Ethiopia, the wonji estate expanded to include an addition of 1,600 hectares of land from

shoa, about seven km from wonji town. The wonji/shoa sugar factory started sugar

production in 1962.

The late king Haile-selassie described this large-scale commercial investment in Ethiopia that

could very well make Ethiopia self sufficient in sugar production and exports to its

neighbouring countries. Emperor Haile-silassie further claimed that with the crushing

capacity of 1600 tonnes of canes per day. Wonji/Shoa sugar factory started as joint venture

between the Dutch, Handlers-Vereeniging Amsterdam (HVA) firm and the Ethiopian

government. The HVA owned about 90 percent of sugar plantation and while sugar factory

owned only 10 percent. Also in its operation of sugar factory, HVA remitted 10 percent of the

invested capital and 15 percent of the annual profits to its headquarters.

With the change of government in 1974, under pro-clamination No 31 of 1975, all the sugar

factory in Ethiopia became nationalized and administered under the centralized bureaucratic

administration of the new military government. Though; the Wonji Company was very

productive until the 1980’s, It eventually stagnated because of the atrocities and red terror

committed by the military government causing competent and effective workers to leave the

factory and run for their lives.

Finally, in 1991 as the ensuing civil war completely devastated the authoritarian apparatus of

the military administration in Ethiopia, the sugar corporation was dissolved by law and all

existing factory were re-established as public enterprise to be run by the Ethiopia sugar

development agency starting in 1992. To revive the sugar industry, the Ethiopia sugar

development agency was formed as a share company of the development bank of Ethiopia,



Ethiopian insurance company and then the existing of three sugar factories (i.e. Wonji, shoa

and metehara) in 1998. Furthermore, under the Council of Regulation Minister’s (No.

192/2010), in 2010. The current Ethiopian sugar corporation was then formed replacing the

sugar development agency.

1.2 Purpose of establishing sugar factory

The most conspicuous reasons for the establishing of sugar Corporation were to:

Grow sugarcane and other yielding crop

To fulfil social need of sugar in the country

Process and produce sugar, sugar products and sugar by products

Sell the products and by-products in domestic and export market

Encourage and supports the sugarcane grower who supply their cane

Cooperate with educational institutions to produce the required type, number and

quality of trained man power for the sugar industry (sugar corporations and Ethiopian

sugar industry profile March 12, 2013).

1.3 Relation of WSSF factory with other sugar factory

The Wonji/shoa sugar factory Corporation is currently carrying out expansion projects within

the existing sugar factory at Metehara, Finchaa, Tendaho and other additional sugar factories

like Beles in the centre of Amhara region, Wolkait in northern Tigray area, Kesem in the

north-eastern of Afar regional state, and six more factories in the south omo zone of the

southeast Nation nationalities and peoples’ region.

1.4 New wonji/shoa sugar factory

This factory to become self-sufficient in sugar production by the end of 2013 and diversify

the products of sugar cane into ethanol, electrical power, fertilizers, and build tissue culture

laboratories, the corporation is visualizing creating the sugar industries to be competitive

enough to maintain a sustainable growth pattern at the international level. In order to develop

trained and disciplined employees the Ethiopian sugar corporation is instructing its

employees in the use of Japanese philosophy of continuous improvement by applying

kaizen’s processes and technology to improve the company’s production culture and

leadership. Kaizen corporate culture is a continuum off resolving cycles of continual,

dynamic and self-motivated practice in the quest of recreation of self-disciplined and self-



innovation organizations. It also is conductive to realization of human potential of all

members of the organization (Minister of Industry, 2011).

To implement kaizen, about 7,537 members of leadership at various levels and staffs of the

corporation and sugar factory have been trained on kaizen, quality control circle (QCC), the

seven types of waste , their causes and their preventive measures and their application

methods. The country plan to increase the sugar production of sugar from 314,000 tons in

2009 to 2.25 million tons in 2015 and 1.25 million tons of sugar and sugar related factory are

to be exported (Minster of Industry , June 2011).

1.5 Main products or service of WSSF

Wonji/shoa sugar factory is mainly depends on agricultural of sugar cane as raw materials

and produces output likes;

White sugar,

Final bagasse,

Electric power and

Final molasses.

This the main supply from the factory, but there are many by-products which is use for

different uses. Example from bagasse, it produces steam in boiler, writing paper, fiber board,

newsprint produced in other factories.

1.6 Main customers or end user from WSSF

Wonji/shoa sugar factory have different plants whose have own purpose; like milling house

plant (input of sugarcane, output of final bagasse and raw juice), clarification and evaporation

house plant (input of raw juice and steam, output of syrups), steam generation house plant

(input of treated water and final bagasse, output of steam,) power generation house plant

(input of dry steam, output of electric current) and pan house plant (input of steam and

syrups, output of sugar and molasses). Those output from different plants have their own

costumers like;



Customers of white sugar (from pan house product)

East Africa (coca cola company)

Moha soft drink factory (Pepsi company)

FAO (food and agricultural organization) the united nation

MEWIT (JINAD) which distribute white sugar to the whole market

of the country.

Customers of molasses (from pan house product)

Belazaf alcohol and liquors factory

Desta alcohol factory

National liquor and alcohol factory

Customers of final bagasse (from mill house)

Tendaho sugar factory for boiler

Customers of electric current (from power generation)

Ethiopian Electric power associated (EELP)



1.7 Overall organization and work flow

Fig. 1: overall organizational work flow

Management

board

General Manager Internal audit

Executive assistant

to general manager

Public relation estate

and environmental

service

Project implementation

and productivity

improvement

Legal service

Management and improvement

service productivity

Commercial

department

Factory and

logistics

division

manager

Agricultural

operation

manager

Finance and

Human

Resource

Manager

Wonji technical

Wonji process

Shoa technical

Shoa process

Logistics department

Confectionery works

Plantation

Dept

LPCD Dept’

Harvesting

dept

Field

equipment

service Dept

Civil eng.Dept

Finance Dept’

Human

resource

department

Medical

department

Secretary



CHAPTER 2

2. OVERALL INTERNSHIP EXEPRIENCE

2.1. How we get in to WSSF

Fig 2: company profile vew

During the end of 3rd year, we collect the internship paper from the department and taking to

wonji/shoa sugar factory at a summary vacation. Wonji/shoa sugar factory confirming our

internship letters request and appreciation to learn during staying in company by dividing

students into different plants, day to day follow up, activities of industries like operation,

maintenance and repair. This helps as by increasing our knowledge and identifying the

problem with appropriate solution.

2.2. Section/plants we allowed to learn in WSSF

In our staying in the WSSF for internship duration, we work on the whole company that are

related to our field and supporting to our project design. But the factory supervisor is

restricted to four plants for four months. Those are:

Juice extraction (milling) plant

Clarification and evaporation plant

Steam generation and power generation plant and

Pan and centrifugal plant

User

Sticky Note

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Fig 3: processes take place in sugar factory

2.2.1 Juice extraction (milling) plant

The main purpose of juice extraction plant is well extraction of raw juice by mill and separate

from final bagasse. This final bagasse has no content of sugar.

Also in this plant there are many machines that are use for different purpose from preparation

of cane to raw juice and final bagasse produce. Those are like;

Cane trucks: this is by lifting the whole vehicle on a tipping platform with the rear gate of

the truck swinging open to allow the cane to discharge into a feeder carrier

Spiller tables: cane is often discharge from large vehicles into elevated feed conveyors

which are wide as the length of the truck or trailers.

Kicker or tumbler: is usually fitted at the top of the feeder table before the cane discharge to

cane conveyor. This consists of a slowly rotating shaft that the cane fails smoothly off the

discharge end avoiding a heavy fall of a large mass of cane.

Cane conveyors: there are many types of cane carries like apron, belt, chain and slot

carriers. They are used to conveyor the cane from the feeder tables to mill.

Magnets: it used almost impossible to prevent the entry of tramp iron into the system.

Removal of tramp iron in this way pays for itself very quickly, since the damage caused to



cane preparation equipment and mill roll can be severe leading to increased downtime and

reduce recovery.

Cane knives: it is driven by electric motor that is used to reduce the height or size of the

piece of cane to the size suitable for handling in the extraction process.

Mill conventional: refers to mill feed and discharge rolls at a common level and vertically

floating top cells. Although some variations was proved successful.

Head stocks: is to maintain the working element particularly the roll in their desired

orientation.

Mill roll: are usually constructed of a shaft of steel, on to which is shrunk a cast iron shell.

Fig 4: mill roll

Mill bearings: the majority of mill bearing are of hollow (ported) construction, either cast

entirely of bronze or comprising a steel housing with a bronze using.

Lubrication: the maximum permissible bearing pressure for bronze bearing is usually 9 to

11mpa, depending on the design and lubrication.Roller bearings: alternatively to bronze

bearing is spherical roller bearings;

low friction

no cooling water needed

no wear of roller journals

reduced roll length between centre (lower bending stress)

Tolerant of small misalignments.

Mill drives: power absorbed by a mill depend on many factory

The crushing rate (power and fibber throughout)

The mill speed (power and fibber x torque)

Mill configuration (no, size and arrangement of roll)



Power lost in bearing

Mill feed method

Mill setting and the hydraulic load on the top of roll

Rotary juice screen: wedge bar type rotary screen for screening unstrained containing 50%

suspended solid/fine cush cush particles. Rotary drum juice collect trough and other parts in

contact with juice shall be SS304. Rotary juice screen shall have auto cleaning system with

water and steam periodically.

Sprockets and supports: if the inter carrier is also to serve as a mill feed roller, the slats will

generally required additional support around the head pulley.

Fig 5: sprocket and the chain

Chevrons: are notches cut into top of mill to assist feeding the bagasse through the mill.

Donnelly chutes: Donnelly observed that the angle of the bagasse feed plate into a mill has a

marked effect on the pressure and hence on the friction grip of the bagasse on the feed roll.

Pusher feeders: are mechanical device designed to forced bagasse into a mill. They are drive

by an electric and have a reciprocating action.

Imbibitions: in order to extract as much as possible of the sugar which it retains, it is

therefore necessary to restore to an artifice, since this moisture contents cannot be made to

replace by water the juice comprising it.



Fig 6: juice returning, screening and imbibitions process

Bagasse conveying:

a) Bagasse belt conveyors: the most convenient and cost effective means to convey

bagasse is by conventional troughed belt conveyors. This belt is used to elevate

bagasse at inclinations of up to 23o from the horizontal, provided that the feed

arrangements are suitable.

b) Bagasse chain conveyors: for bagasse conveyance, chain and slat conveyors are more

costly initially and in maintenance than are belt conveyors of equivalent capacity.

Their use is usually confined to applications where belts are not suitable. Example

are:

Where elevations steeper than 23o are required.

Where multiple off takes are required.

Where bagasse is transported in both direction.

For feeding bagasse in to boiler chutes.

Bagasse feeding to boiling: for satisfactory boiler performance, bagasse must be fed reliable

at high rate into narrow enclosed chutes, keeping them full without chocking or generation

excessive dust.

Juice recycling: apart from the first mill, the juice from the first extraction stage of a mill

(e.g. from the pressure feeder of a pressure fed mill or the first roll of a four roll mill) is

generally of lower brix than the average for the mill. Recycling can be usually be taken to

saturation of the feed materials, which is a wetness level of 500% to 600% on fiber, beyond

which there is no benefit to be gained.



2.2.2 Clarification and evaporation plant

The aims of clarification are;

To form floes to trap all suspended matter which can be at satisfactory rate

To produce clarified juice of high quality with a minimum turbidity, colour, and a low

calcium contents.

The aim of evaporation also;

To remove water from juice up to desired brix and to thick juice or syrup without any

change in sugar and reducing sugar.

To maintain clarified juice PH around (7±1)

Some machines used in these plants are:

Juice mass flow measurement: it is commonly practice to employ batch scales to measure

the mass of raw juice produced. Because of most other metering device do not approach the

same accuracy.

Batch scales: a batch scale system consists of supply tank above a weight hopper, which

accept batch of juice and records the mass before discharging. The weight hopper is tarred

before accepting a new batch. This weight hopper is supported on three or four load cells to

record the mass.

Juice pumping: raw juice contains some sand and fibrous bagasse particles and is abrasive

and corrosion. To specify the pump duty, it is necessary to know the average and maximum

flow rate to be pumped including filtrate return, as well as the head on the pump under both

conditions.

Fig 7: juice pumping



Pump selection: the total pump head required is made up of the following.

The difference between liquid levels on suction and discharging sides.

Any difference between vacuum and/or pressire on the inlet and outlet side liquid free

surface

friction i.e. the head required to overcome resistance to follow through pipe and

fitting

pressure drop across the control valve

head loss through equipment such as heaters in the system

The velocity head at final discharge.

Plate heater: the plate heater is a pack of thin plates arranged in a frame so that the space

between each alternative plate is open to the same fluid.

Flashing: the purpose of flashing is to force outlet the air presents in the juice, to cause the

bagacious particles to burst and then sink with the flock and to insure constant flashed juice

temperature. A practical check on flashing is to observe the vapour coming out of the flashing

tank vent, if there is no vapour than flashing is not taking place.

Filtration: the clarification process separates the juice in to two layers;

The clear juice, which rise to the surface.

The mud which collects at the bottom.

The clear juice goes to manufacture that is direct to evaporation. But the mud has first to be

filtered, in order to separate from the juice the suspended matter which it contains, with the

absolute salts formed and the fine bagasse entrained with them.

Flocculated mud settles in the clarification process in the lower layer and the under flow is

removed at a steady rate. The mud has then to be filtered to recover the juice from the soil

and mud solids, mostly with the addition of fine bagasse particles, known as bagacillo, as a

filtration aid. Filtrate is returned to the juice heating system.

The operation of the mud withdrawal from the clarified compartment is regulated by the

operator to keep the mud upper level in the clarifier close to a desired target. Various aids to

the operators have been used. These involve variable speed mud pumps, and draining off the

mud for timed periods, combined with maintaining a constant level in a mud-receiving tank.



The advantage of filtering is only mud derived from weak juices: hence also the advantage of

substituting water for the juice in the cake, by washing, and by carrying the washing as far as

possible.

The disadvantage of this type of filter is overload the clarification station. When the latter is

working near the limit of its capacity, it is undesirable to increase the volume of the jiuces,

and consequently their speedof circulation in the clarifier, by a fraction which represents

approxmately.

Fig 8: Oliver campbell

Evaporation:

The clarification process has given a clear juice. This consists of sugar dissolved in water,

together with certain impurities. Now that we have removed the impurities as far as possible

it remains to remove water.

Pre-evaporators: refers to an evaporator that is dedicated to vapour bleeding. Juice

from the pre-evaporation feed the first effects that use exhaust steam for evaporation.

Optimum operating condition: the best performance from an evaporator set is

obtained when it is run as steadily as possible. This is generally achieved through the

use of automatic controls.

Effect of superheat: if the superheat is excessive, it is possible for the heat transfer

rate to be affected adversely. In this case a significant proportion of the heat transfer

has to take place from the vapour phase to the tube surface, rather than by the far

more rapid form of heat transfer in condensation.



Flash pots: if vapour flashing is to be practiced, the condensate is usually collected in

a receiver or flash pot, which has to be sized to permit the flashing to occur without

re-entraining too much liquid.

Syrup pumping: because syrup is extracted from the last effect at its boiling point,

the NPSH (net positive suction head) available on the pumps may be low. In addition

is common to install a strainer on the pump station, which, if it blocks; introduces a

suction line pressure drop that makes the situation worse.

2.2.3 Steam and power generation plant

The aim of steam generation is;

To produce steam from boiler by burning of dry bagasse in furnace and heating

treated water in boiler.

The aim of power generation is;

To produce electric power by steam that is produced in steam generation plant in case

rotating turbine for the factory and for other customers like ELPA.

Steam generation plant

The amount of steam generated from bagasse depends on the efficiency of the boiler. The

pressure at which the is generated and the calorific value (determine by moisture and ash

contents) of the bagasse.

The amount of bagasse lost in the raw juice and the filters depends on whether milling or

diffusion is being practiced.

Some machines used in this plant are;

Bagasse distributors: because of its low density and high drag coefficient bagasse is best

distributed pneumatically rather than mechanically in to furnace.

Fans: a boiler to operate successfully it must have enough grates to allow the fuel to be

burned efficiently and enough fan capacity to provide the air required to complete

combustion and exhaust the products of combustion from the unit. Four types of fans:

o Primary air fan: supply hot air to the underside of the grate

o Over fire air (OFA) fan: supplies the additional air required to combustion.

o Induced draft (ID) fan: exhausts the products of combustion from the boiler to

atmosphere

o Distribution air fan: used to convey the bagasse in to the furnace



Furnace: has to be equipped with a fuel feeding system, an air distribution system and an ash

removal system.

The grate: in step grates, combustion takes place on the steps. The dead plate which

precedes them serves to remove the excess moisture from the bagasse before it comes to the

grate. The ash grate which follows the steps grate serves to complete the combustion and

utilise the heat transmitted by radiation from the incandescent bagasse the ashes are dropped

in to the ash pit.

Heating surface: the heating surface comprises that of the boilers tube and the tube of water

walls, when these are provided. The total heating system/surface has no great signification in

modern boilers, an account of the difference in rate of heat transfer existing between the

difference components of the boiler units.

Boiler bank: the steam drum and boiler drum are connected by a set of tube are called bank

tubes. The boiler bank is almost a convection heat transfer section.

Air pre-heater: air heater can be successfully employed to recover heat from flue gas at

lower temperature level than is possible with economizer. The heater rejected chimney can be

reduced to higher extent thus increase the efficient of the boiler.

Deaerator: the solubility of oxygen, air and carbon dioxide in water is a function of the

water temperature. Deaerators use steam for clear water for boiler.

Feed water treatment: dosing should take place as far upstream as possible to protect the

pre-heater system as well.

Steam usage: process steam usage of the cane mill depends on such factors as cane crush rate,

number of evaporator effects target sucrose extraction and hence imbibitions % fiber and use

downstream evaporator vapour for pan and juice heating.

Power generation plant

To optimize mill electricity generation, the following parameters must be considered:

process steam demand

bagasse availability for fuel

factory electrical demand

irrigation power requirements

electricity sale price

cost of supplementary fuel

emergency power sources



Steam turbines: steam turbines take in steam at relatively high pressure and temperatures

and exhaust the steam either to process, or in some cause to a condenser operating under sub-

atmosphere pressure. For a constant Steam flow through the turbine (i.e. no steam bleeding),

the difference in total heat per unit mass (specific enthalpy, KJ/Kg) at the steam inlet and the

outlet of the turbine. Represents the energy extracted from the steam in the form of

mechanical work, used either to drive a mechanical load, or to drive a rotating alternating

current generator.

Impulse or impulse-reaction turbines: steam turbines are either “impulse” or “impulse-

reaction”. There are no pure reaction turbines.

In an impulse turbine, the steam pressure is caused to drop across stationary nozzles,

generating high steam velocity with increased kinetic energy. This high steam

velocity steam impinges on moving blades which extract the energy by reducing the

velocity. There is no pressure drop across the blade moving. This turbine is simpler

and cheaper because there no pressure sealing across the moving blades. The

efficiency of this turbine is around 84%.

In an impulse-reaction turbine, which is always multi-stage, there is a steam pressure

drop across both the fixed and moving blades. This turbine is more efficient because

there are more stages of steam pressure drop, each of which has fewer losses. The

efficiency of this turbine is around 78%.

Transformers: transformers transform electrical power from one supply voltage to another,

with high efficiencies, typically 98 to 99%. Transformer must be operating within their

design limits as regards current, voltage and operating temperatures. Maintenance of

transformers also include elimination of oil leaks, maintenance of breather desiccant,

ensuring adequate cooling and most important, regulate oil quality checks followed by oil

drying and filtering.

Use for bagasse: excess bagasse may find very profitable use as,

Raw material for the manufacture of fire proofed insulating boards used for building

purpose

Raw material for the fabrication of paper pulp

Raw material for the manufacture of various solvents utilised in industry.



2.2.4 Pan and centrifugal plants

The objective of centrifugal is also to separate massecuite from the surround molasses or

matter liquids.

The objective of pan house is also to obtain maximum amount of sugar syrup through

crystallization by concentration under vacuum in vessels. The crystallization stage in a sugar

house involves crystallizing as much as possible from evaporator syrup.

Crystallization in a vacuum pan continues until the point is reached where further

crystallization would result in a massecuite that stops circulating or that cannot be discharged

from pan. Massecuite leaving a vacuum pan is supersaturated and hot, in the range 63 or

75oc.

Feed tanks: syrup A and B molasses are usually stored in tanks on the ground floor, with

small feed tanks provides on the pan floor, from which the feed passes to the pans.

Vacuum seed receivers: are often provided on the pan floor provide flexibility in pan floor

operation. These vessels are normally cylindrical in shape, insulated, and with a horizontal

stirrer rotating at about 1min that scrapes close to the internal surfaces.

Strike receivers: these U-shaped horizontal troughs fitted with horizontal rotating stirrers.

The receive massecuite from batch pans on strike, and provide a buffer between the bath pans

and continuous crystallizers or centrifugals.

Centrifugal separation: after crystallization, the sugar crystals are separated from the

massecuite by centrifuging. Because of the nature of the mother liquor, particularly the high

dissolved solids content and high consistency, centrifugal forces need to be high, requiring

high speed machines.



Fig 9: centrifugal separation

Centrifugal drives: is machines were driven by fixed speed motors or pole-changing motors

to accommodate the different speeds required for spinning, feeding and discharging.

Feed mixers: a horizontal feed mixer is usually installed close to the centrifugals, which are

fed from the mixer through one or more valves.

Washing: this is achieved by addition of water and steam. Because of the short time the

machine crystal dissolution is low. The extent to which the water and steam mix with the

mother liquor to reduce its viscosity and the extent to which the water and steam actually

wash the molasses film off the crystal is know.

Seed growing pan: the basic material used in the pan boiling is syrup of 50 to 65 % brix and

80-85% purity. The PH is also between 5-5.4. The brix of the sugar is assumed as 100%. As a

result the concentration of syrup to massecuite is from 60-100% brix. This is achieved by two

ways as below

o Concentration of 60 to 100% brix

o Formation of sugar crystal

Rotary cascade drier: is which has comprises a cylindrical drum, rotating at a slight slope to

the horizontal, running on steel rollers or cradles. The holdup of a rotary drier varies with the

feed rate, the number of flights, the shell diameter and the air rate.

Rotary louver driers: unlike the cascade variant, little design information has been

published on rotary louver driers, perhaps because they are designed by relatively few

suppliers, and the information is regarded as proprietary.

Screw conveyors: these devises comprise a central shaft running along the axis of a U-

shaped trough, with a screw or helical ribbon attached to the shaft. The greatest disadvantage



of this type conveyor is that the sugar crystals may be ground between the screw and the

shell.

Vibrator conveyors: this operates on the same principle bit using high frequency vibration.

These can be enclosed (dust-free) but consume more power and certainly classify the sugar.

Twin conveyors: overcome the vibration problem of a grasshopper by oscillating two

identical units 180o out of phase.

Slip-stick conveyors; are a recent innovation, operating by means of a slow forward stroke

followed by a rapid return stroke. They rely on the sugar slipping on the return stroke to

advance the sugar along the conveyor.

Belt conveyors: are continuous belts consisting of several plies of fabric impregnated,

bonded and coated with rubber. These run on idler, spaced at intervals of about 1 to 1.5m for

the top, load-carrying strand and much larger spacing’s for the lower, empty strand. Belt

conveyors may inclined, does not recommend more than 22.5o for dry sugar. Prefers a limit

of 20o and recommends 16o. Belt speeds of 1.2 to 1.6 m/s are common, except for ship-

loading conveyors which can run at around 2.9 m/s.

Fig 10: sugar conveying belt

Bagging and packaging: sugar packaged into sack, bags and packages ranging in size from a

few grams to 1000kg. Bags for commercial customers are usually 25kg, 50kg and 100kg.



2.3. The piece of work we have been executing

During the internship period, we were working in the preparatory section and loom shed. In

this group, we were working maintenance of different parts of the machines. The term

maintaining can be defined as something to repair or to bring functional which were non-

functional due to many problems. In this time, we were able to know different machine parts,

which we learned in the last seven semesters of our educations. In addition, we know how to

maintain machine parts and we can see the integration of mechanical and electrical machine

parts.

2.4 Procedures we have been using during performing our work tasks

The procedures we were following during our internship practice are-

First, we understand how the machines operate.

Then we ask the operators and maintenance workers how the work is to

be executed

And after that we try to do the jobs ourselves and if we get problems

which need further

explanation and something we don’t know we write down them and

discuss at our break

time and discussion time with our supervisor and try to know more

There were many textile activities, which are not concerned under

mechanical, and these terms were difficult to understand for us.

2.5 How we was good in performing our work tasks

As our supervisor told us and comparing, what we do with what we learn and with what the

other workers do, we were very nice. We were also punctual and well enter acted with the

workers. And the other thing that makes us to say we were very nice is we were not only

asking for our supervisor to know more but also we were referring different books and web

sites related to the department we have been working.



2.6 Challenge we faced while performing our work

During the training in the company, we faced many challenges that influence our work. This

includes:

Number of student increase at one place

Sound of some machine can be disturbed

Load capacity on the supervisor

No internet coverage in the company

Environmental is also very hot

Some other student limitation of language

2.7 measures we take in order to solve the challenge

In order to solve those challenges we take some measure

Following day to day

Active participating

Gather information by interview and observation about machine in whole plant

Asking experienced technical documentary room

Referring manual document from different room



CHAPTER 3

3. OVERALL BENEFIT OF THE INTERNSSHIP

After completing the training we gained many benefit from this internship program like the

following:

Improving practical skills

Upgrading theoretical knowledge

Improving its interpersonal communication skills

Improving team playing skills

Improving leadership skills

Understanding about work ethics related issue

Entrepreneurship skill

3.1. Improving practical skills

Wonji/shoa sugar factory is a huge company in our country that produce sugar for the

costumers. So it goes in different process and plants. Due to this complex process there is

some linkage, broken of machine, corrosion, bending and disassembling are occurred.

Therefore, to solving this problem there are many ways taking like welding, assembling,

engaging and disengaging of the gear, valve, pump, pipe and tanks. Also how hydraulic and

pneumatic system is worked.

So, we really understanding by seeing, sharing aid with the operators of that place and also

working with them practically. This encourages as increasing our confidence to operate the

machine by itself.

3.2. Upgrading theoretical knowledge

Theoretical knowledge is prerequisite for practical provision of recommendation for

maintenance activities. For examples,

Pump selection: the total pump head required is made up of the following;

o The difference between liquid levels on suction and discharge sides

o Any difference between vacuum and/or pressure on the inlet and outlet side liquid

free surfaces



o Friction, i.e. the head required to overcome resistance to flow through pipes and

fittings

o Pressure drop across the control valve

o Head loss through equipment such as heaters in the system

o The velocity head at final discharge

Bearing selection: the following consideration takes place for selection of bearing

o Low friction

o Minimum lubrication use and no contamination of juice

o No cooling water needed and no wear of roller journals

o Tolerant of small misalignments

o Reduced roll length between centres (lower bending stress)

Valve selection: to select the exact valve for replace or change must to know

o Valve weight

o Valve stroke

o Valve opening orifice area (A0)

o Valve cross section area (Av)

o Friction loss at delivery and waste valve

If pump is stop working it should be replacing by other pump. During replacing some

consideration should also take place like, pressure of suction side and discharging side, types

of pump we selects, speed of rotation and number of impellers and size of the pumps.

Therefore upgrading theoretical knowledge we applied our skill at real world practices

without any confusion.

3.3. Improving interpersonal communication skills

Wonji/shoa sugar factory has different plants from cane transporting to sugar story house.

This is done by its group of workers in different plants. During their team works they are

communicating to each others, putting idea if some problem was occurred and supporting

their idea for solving the problem.



Communicating to each other’s is facilitating their jobs and increasing the productive of the

sugar supplying for their customers. Therefore we can also gained many wisdom from

company worker by asking and changing idea to each other.

3.4. Improving team playing skills

Working with group is the one which facilitate the productivity of the factory. So we improve

the team working skills by discussion with our supervisor and his colleagues in different

action and solving problems. This team playing skill is that necessary in all anyway, because

one support others to increase their productivity in all case. So we can improve the team

playing skills by decision making in group where some problem are exists.

3.5. Improving leadership skills

In WSSF there are many work flow in different plant from company manager to the last

labour that decrease the load on someone and this increase the company profited. From this

we ensure the following improvement:

Ability to solve problem quickly

Understand behaviour of the worker and manage them properly

Facilitate the new idea from this colleagues and making decision

3.6. Understanding about work related issues

To fulfil of the goal one product, ethics has its own advantage. Because, in any company if

there is environmental health, work division, enough material and no corruption the

productivity and supply of the company is increase. We also gain this work ethics during us

staying in WSSF. Therefore we also some work ethics like

Punctuality

Keeping rule and regulation of the factory

Safety first

Honesty

Accountability and transparency

Responsibility

Polite communication with manager and colleagues



3.7. Entrepreneurship skill acquired

Entrepreneurship is the process of creating something new with value by devoting the

necessary time and effort, assuming the accompanying financial, psychics and social risks

and receiving the result reward of Monetary and personal satisfaction of independency. This

is gained by the following characteristics.

Low fear of failure

Self-confidence

Use of feed back

Use of resource

Clear goal setting

Internal locus of control

Long term plan

Therefore from the above characteristics we acquired the concept of the entrepreneurship for

putting idea of new creation or modifying the existing material for increasing the capital of

the individual and members.



CHAPTER 4

4. PROJECT DESIGN

4.1 PROBLEM IDENTIFICATION AND THEIR PROPOSED

SOLUTION

In WSSF, the corporation between the worker is solve more problem occurred in the

company. But some problem occurs at different place/plants. We are also identified at least

four problems that is available in this factory:

Steam pipe: This problem is occurred in steam generation plant. The pipe use in this

plant is not well give function. Because of pressure drop across the pipe, steam was

leaved pipe. The longer distance has flow, the lower velocity we shall choose for the

steam, so as to avoid excessive pressure drop.

Bulk pile storage of bagasse: In wonji/shoa sugar factory, this problem is occurred at

final bagasse storage area which discharged from mill plant, Because of the large area

involved this usually means storage in open air. Pile management of the company

becomes important in maintaining sloping piles and ensuring that no dams from

which can catch and hold water.

Conveying problem: In the company material/product are conveyed by the belt at

many areas. This belt is repeatedly failed and material is stored for long time without

giving function. So we have an idea to change this conveying by chain that has long

life without any fail.

Ash conveying belt: This problem is occurred in steam generation plant that after

bagasse is burned in furnace and the waste of bagasse ash and smoke gas are to be

discharged. Smoke gas is taking to chimney to release the gas to outside or

environment. But ash is taking to discharge by means of belt. This belt is usually out

of function because of the burned bagasse has maximum temperature. So the

concerned company manager take to solve this problem by take the minimum

reduction with belt to fall and increase the belt quality to resist heat of ash.

So from the above problem those occurred in the WSSF, we select “design of roller

conveying chain” to solve the problem of material conveying from one place to other place.



4.2 PROBLEM SELECTED (ROLLER CONVEYING CHAIN)

4.2.1 Introduction

Roller conveying chain is mostly preferred in sugar factory to transport goods like sugar by

sack. This roller conveying chain is to solve the problem occurred in the factory that the

sugar sack is conveying to the sugar storage area..

Belt conveying has the following problem:

It has more linkage

Has maximum slip due to smooth surface

Fails under high temperature

Low carrying capacity i.e. convey only 50kg per meter length

Therefore roller conveying chain we design has the following advantage over belt conveying:

Carry heavy load i.e. 100kg per meter length

Discharging rate is maximum

Required low human power and low cost

Operate at high temperature

Reduce the labour and time of convey/transport

Low maintain

Long life

Has no linkage, slip and failure like a belt

4.4.2 Design analysis

Drive end: Apply driving power to the discharge end of a conveyor so that only the

carrying run is under maximum tension. Apply power to the head sprocket through

another chain and sprocket.

Pre-tension and take-ups: Provide take-ups in all conveyor installations to ensure

slack for installation and maintenance and to compensate for elongation due to wear.

Install the catenary take-ups at the head end of the conveyor; install all other take-ups

at the foot or loading end of the conveyor.



Points to consideration

1. Ensure that chains always engaged with at least three sprocket teeth

2. For long conveyors use take-up devices to eliminate chain slack. Take-up

stroke = (c*0.02) =S

Where: c = center distance between sprockes

S = catenary sag allowance

But this equation is for conveyors longer than 50ft.

Long shaft centre distances: For unusually long shaft centers, either use two

conveyors with a transfer point or use bearing roller chain.

Return chain supports: On chain conveyors more than fifteen feet long, support

the return strand on a track or guide to minimize pulsation and whip and to prevent

the sagging chain striking obstacles

Operating temperatures: Standard conveyor chain can be operated normally in

ambient temperature between 150F and 1400F. Select the appropriate chain for

condition out of this range, including operation in freezing chambers or heat-treatment

ovens.

4.2.3 Material selection

The material selection for our design has the following consideration:

Availability of material

Low cost

Suitability of the material

Easy replaced/maintain

We take material selection from appendixes table 1.

The frame:

The frame is the basic component on which all the other component is tight on it. It used for

supporting the overall weight of the machine. This frame is 10m in length and 1m in width.

This frame is carry the weigth of the sugar conveyed up to 10 quintal of sack and the weigth

of the chain, sprocket, slat and motor up to It is made up of rectangular steel bar that

structure is shown as below.



Fig 11: supporting bar

Slats:

The slats are where the product is carried on it. This slat is made up of light metal which is

resist the friction, rust and corrosion. This is shown below

Fig 12: slat

Nut and bolt:

Bolt and nut are used to tight the component of the machine together for have same rotation

and reduce sliding. Bolt and nut are shown as fig below

Fig 13: bolt and nut

User

Sticky Note

2.1. How we get in to WSSF Fig 2: company profile vew During the end of 3rd year, we collect the internship paper from



4.3 DESIGN AND CALCULATION

4.3.1 Design of chains

In the design of chain, some consideration takes place

No slip takes place during chain drive

It gives high transmission efficiency (up to 98%)

It transmits more power

It transmit horizontal convey

To simplify the design process, the following assumptions are made depending on the desired

geometry and shape of the machine.

Module, m =4mm

Diameter of sprocket 1 = sprocket 2 = sprocket 3 = sprocket 4 =650mm

Velocity ratio of the chain drive and sprocket is 1

Appropriate center distance for pitch diameter of 250mm, x = 10000mm

Rotational speed of the motor, N = 900 rpm

Rotational speed of the shaft sprocket N =60rpm

Power transmitted by the driven pulley is 12KW

Roller type chain

From these values, we calculate

Number of teeth for each sprockets, T1 =T2 =T3 = T4

T = ∏*D/p

T = ∏*650/250 = 8.16

T =8

To calculate the length of chain and number of chain

The length of one side chain, L = B*P, where B = number of chain of one side

To calculate the total length of the chain

L = 2*length of travelled + 2 (½ ∏*diameter of the sprocket)



Diameter of the sprocket is Ds = P*cosec(180/T)

Where T = number of the teeth

P= pitch

Ds = diameter of the sprocket

Ds = 250mm*cosec (180/8)

Ds = 650mm

Therefore L = 2* 10000mm + ∏*(650)

L = 22041mm

We also calculate the number of chain

B = L/P

B = 22041mm/250mm

B = 88

From the appendix table 2; For roller type chain with the speed of the sprocket 60rpm, the

factory of safety for chain can be taken as, n = 7

Pitch line velocity of sprocket; V=∏*Ds*Ns/60=∏*0.65m*60rpm/60=2.04m/s

Load on chain W = rated power/pitch line velocity = P/V

W = 12KW/2.04m/s

W = 5.88kN

The total load of the chain, W =��

� ,

n = safety factory = 7

Therefore the breaking load on the chain is calculated as

Wb = W*n = 5.88KN*7

Wb= 41.16KN



4.3.2 Design of sprockets

In the conveyor two chains and four sprockets are employed it is nprmal practice to keyway

the driving sprocket to the shaft as a pair. The teeth should be in line to ensure equal load

sharing. When a pair of sprockets is mounted on a shaft the long bosses of the sprockets

should be assembled so as to face each other, i.e. towards the shaft midpoint. This allows the

sprockets to lie close to the shaft bearing, giving maximum support to the load, while at the

same time required only the minimum width of conveyor structure.

Fig 14: sprocket

For the pitch diameter of 250mm and number of teeth is 8

The diameter of the sprocket is D = PT/∏

D = 250mm*8/∏

D = 636.9mm

Therefore from standard table we take diameter of each four sprocket is D =650mm

The torque applied on the tooth of sprocket is

Torque = chain pull x radius of the sprocket

Torque = W*r = 5.88kN*0.325m

Torque = 1.911kNm



4.3.3 Design of shaft

Shaft is a rotating member, usually of circular cross-section, used to transmit power or

motion from one point to the other. It provides the axis of rotation or oscillation of elements

such as gear, pulley, flywheel, cranks, sprockets and the like. An axle is a non-rotating

member which carries no torque and is used to support rotating wheels, pulley, and the likes.

Types of shaft

Shafts are classified as follows according to their industrial application.

Line spindle: It is a shaft which transmits power to several machine elements.

Spindle: A spindle is a short revolving shaft. Example: head stock spindle, drill press spindle

etc

Stub shaft: a shaft that is integral with an engine, motor or prime mover.

Counter shaft: A short shaft that connects a prime mover to a line shaft of a machine

According to the application, shafts may be divided in to two types

Transmission shafts: these shafts transmit between the source and the machines adsorbing

power. Counter shaft and line shafts, over head shafts and all factory shaft are transmission

shafts. Since these shafts carry machine parts such as pulleys, gears etc. Therefore they are

subjected to bending in addition to twisting.

Machine shaft: these shafts form an integral part of the machine itself. Example: crank shaft,

stub shaft.

Shaft material: When greater strength is required, as in high-speed machinery, such as

nickel, or chrome vanadium steels are used. When resistance to corrosion is desired, some

copper alloys are used. The material used for shafts should be have the following properties

It should have high strength

It should have good machinability

It should have low notch sensitivity factory

It should have good heat treatment properties

It should have high wear resistant properties



For calculation of design of shaft we select the plain carbon steel C-30 for all shafts from

appendixes table 1.

Having selected the size of conveyor chain required for a system, another important is the

diameter of the sprocket shafts. The head shaft takes the greatest stress and attention for

design.

We select two shaft one for drive and other for driver

i. Design for drive/head shaft

This shaft is subjected to two supporting bearing, force applied on the sprocket and also force

applied by transmission drive motor pulley.

Fig 15: Schematic diagram of drive shaft

For roller conveying chain the weight applied by sprocket is the summation of:

Weight of the total conveying sugar sack for 10m are 10 quintals per unit length i.e.

Wp = 10x100kgx10m/s2 = 10000N. But this weight is equal disturbed on four

sprockets equally, for each spocket weight = 10000N/4 = 2500N

The pulley shaft drive force by is 500N

Calculation of maximum bending moment

The maximum bending moment induced in the conveyor head shaft. From the diagram the

arrangement of two conveyor sprockets are located equidistant from the respective nearby

shaft bearing (40mm), whilst the transmission chain sprockets on the overhanging shaft, that

distant from the one end of the bearing (50mm).



FP=500N 140mm FSC = 2500N FSD =2500N

A B C D E

FRB 100mm 900mm 100mm FRE

To calculate the maximum bending moment on the shaft, first calculate the reaction force.

Therefore to calculate the reaction force at point E we take the summation of moment at point

B is zero.

∑MB= 0

-500Nx140mm + (2500Nx100mm) + (2500Nx1000mm) - FRE*1100mm = 0

FRE = 2436N

To calculate the reaction force at point B, the summation of force along y-axis is zero

∑FY = 0

-500 + FRB -2500 – 2500 + 2436 = 0

FRB = 3064N

Therefore to calculate the maximum bending moment, for each section

Section AB

140mm ∑MB = 0

A B FV MB = 500Nx140mm

MB = 70000Nmm

The shearing force at point b is

∑FY = 0,

-500N + FV = 0,

FV = 500N



Section AC

500N 140mm FV

A B C

3064N 100mm

∑MC =0

-500Nx240mm + 3064Nx100mm - MC =0

MC = 186400Nmm

The shearing force at point C is also

∑FY = 0

-500N + 3064N – FV =0

FV = 2564N

Section DE

∑MD = 0

MD -2436Nx100mm = 0

MD = 243600Nmm

FV D E The shearing stress along y-axis is zero

100mm ∑FY =0, -FV + 2436N = 0

2436N FV = 2436N

At point A and E the bending moment of the shaft is equal to zero and the maximum bending

moment is at point D that is 243600Nmm. So from the above data we draw bending moment

diagram



500N 2500N 2500 N

A B C D E

3064N 2436N

243.6Nm

186.4kNm

Mb

70Nm

0

Shaft length in mm

Bending moment for driven shaft

Therefore the above diagram the maximum bending is Mmax = 243.6KN

Calculation of twisting moment (TORQUE)

Torque on the shaft is calculated as

T = 60P/2∏N = 60*12kW/2∏*60

T = 1910Nm

From equivalent bending moment

Meq = √(kbMb)2+(ktT)2 where kb and kt is 1 for stationary load applied

Meq = √(243.6KNm)2 +(1.91KNm)2

Meq = 243.6KNm



From appendix table 7; Ultimate tensile strength for material we selected plain carbon steels

of C-30 is 550N/mm2 and yield strength is 300N/mm2

For the safety factory of 7

We know that the allowable tensile stress

�� = ��/� = 550mpa/7

�� = 78.57mpa

Therefore �� = 32Meq/∏d3

d3 = (32Meq/ ∏��

d3 = (32x243.6Nm/∏*78.57*106N/mm2)

d = 0.0318m

d = 31.8mm

From the standard of the shaft diameter it take, d = 38mm

From equivalent twisting moment

The maximum torsion stress occurred is

�� =��

��x Te where � = shearing stress, Te = equivalent torque

d = diameter of the shaft

The torque transmitted by the shaft

T = Px60/2∏N = 12X60X103/2∏*60, T =1910Nm

The allowable shearing stress is equal to

�� = ��/2

�� = 300��/2

�� = 150Mpa



From this the diameter of the shaft is calculated as

d3 = 16Te/∏ ��

d3 = 16*1910Nm/∏*150*106N/m2

d = 0.0401m

d = 40.1mm

From the standard shaft diameter we select, d =44mm

Therefore from the two equivalent moments the maximum shaft diameter is allowed. So the

shaft diameter for drive is d =44mm

ii. Design for driven shaft

This shaft is subjected to bearing supporting at both side and two sprocket that is equal

distance from bearing.

Fig 15: Schematic diagram of the driven shaft

This shaft is applied force by two sprocket (each of weight of 10kg * acceleration due

to gravity 10m/s2), F1 = F2 = 2500N

Also it is supported by two bearing that located by pins located from sprockets by

140mm distance apart.



Calculation for maximum bending moment

FSB=2500n 900mm FSC=2500N

A B C D

140mm 140 mm

FRA FRD

The force applied at point B is 2500N by sprocket, so to calculate the reaction at D we taking

a moment at point A is equal to zero.

∑MA = 0

(2500N*140mm) + (2500N*1040mm) - (FRD*1180mm) = 0

FRD*1180mm = 53000Nmm

FRD = 2500Nmm

To get the bearing reaction at point A, we calculate the summation of all force along y-axis is

zero

∑FY = 0

FRA – 2500N -2500N + FRD = 0

FRA – 2500N -2500N + 2500N = 0

FRA = 2500N

To calculate the maximum bending moment for each point, it is calculate for each section.

For section AB

140mm FV ∑MB =0

A B MB -2500N*140mm = 0

FRA = 2500N MB = 35,0000Nmm

To calculate the shearing force, summation of force along y-axis is zero,



FV –FRA =0

FV = 2500N

For section CD

FV ∑MC = 0, MC – 2500N*140mm = 0

1 40mm MC = 350,000Nmm

C D FD = 2500N

To calculate the shearing force along y-axis the summation of force is zero.

FV – 2500N = 0

FV = 2500N

Therefore the maximum bending moment is obtained at point B and C is 350000Nmm and

the minimum bending is at point A and D will be zero. From the above data we draw the

maximum bending moment diagram.

A B C D

Mb 350000Nmm

0

Length of the shaft in mm

Therefore the maximum bending moment is obtain at point B and C are Mmax =350Nm

User

Sticky Note



The torque due to sprocket on the shaft is,

T = F sprocket * radius of the sprocket

T = 5000* 325mm

T = 1625000Nmm

From the maximum bending moment and torque produced, we calculate the equivalent

moment,

M eq = �(�t�)� + (��)�

From the appendixes table 5; we select kt for torsion and kb for moment that is applied load at

stationary. Therefore, kt = kb = 1

Meq = �(�t�)� + (��)�

Meq = √(1625000)2 +(350000)2

Meq = 1662265Nmm

Calculation for twisting moment (TORQUE)

For the driven shaft rotate at similar to drive shaft by 60rpm and the power of 12KW, the

torque applied on the shaft is calculated as

T = 60P/2∏N

T = 60*12X103/2∏*60

T =1.91KNm

From equivalent bending moment

Meq = �(�t�)� + (��)�

Meq = √(1625000)2 +(1910)2

Meq = 1662265Nmm

For the shaft material of plain carbon steel C-30, the ultimate tensile strength is 550N/mm2

and yield strength is 300N/mm2, The safety factor of 7



The allowable tensile stress is calculate as

�� = ��/� = 550mpa/7

�� = 78.57mpa

Therefore to calculate the diameter of shaft

�� = 32Mmax/∏d3

d3 = 32��/∏��

d3 = 32x1662.265Nm/∏*78.57x106N/m2

d = 0.05995m

d = 59.9mm

From the standard shaft table we take d= 65mm

4.3.4 Design of the key

Key is piece of mild steel inserted between the shaft and sprocket to connect these together in

order to prevent relative motion between them. Key is used as temporary fastening are

subjected to considerable crushing and shearing stresses.

Types of key

Sunk keys

Saddle key

Tangent keys

Round key

Spline key

From the above key, key that we select is rectangular sunk key. The usual proportions of this

key are



For driver shaft,

For the d =44mm

T = 1910Nm

�� = 150Mpa

Width of the key, w = d/4 = 45mm/4 = 11.25mm

Thickness of the key, t = 2w/3 = d/6 =45mm/6 = 7.5mm

Length of the key,

T = F*d/2 =�*w*l*d/2

L = 2T/ �*w*d = 2*1910Nm/150*106N/m2*0.01125m*0.044m

L =0.0514m

L = 51.4mm

For driven shaft

For the d =65mm

T = 1910Nm

�� = 150Mpa

Width of the key, w =d/4 = 65mm/4 = 16.25mm

Thickness of the key, t = 2w/3 = d/6 = 65mm/6 = 5.4mm

Length of the key,

T = F*d/2 =�*w*l*d/2

L = 2T/ �*w*d = 2*1910Nm/150*106*0.01626m*0.065m

L = 0.0237m

L = 23.7mm



4.3.5 Bearing selection

A bearing is machine elements which support another moving machine element. It permits a

relative motion between the contact surfaces of the members, while carrying load. A little

consideration will show that due to relative motion between the contact surfaces, a certain

amount of the wasted in overcoming frictional resistance and if the rubbing surfaces are in

direct contact, there will be rapid wear. In order to reduce frictional resistance, wear and in

some cases to carry away the heat generation.

Roller conveying chain has used bearing at shaft supporting end. This bearing we selected

has the following consider

Low starting and running friction

Ability to withstand momentary shock

Accuracy of shaft alignment

Low cost of maintenance

Small overall dimensions

Reliability of service

Easy to mount and erect

Cleanliness

Lubrication of bearing

Bearing are lubricated for the following purposes:

To reduce friction and wear between the sliding parts of the bearing,

To prevent rusting or corrosion of the bearing surfaces

To protect the bearing from water, dirt, etc., and

To dissipate the heat.

For driver shaft of the diameter of 45mm we select the bearing number 209 are selected and

also for the driven shaft of the diameter of 65mm bearing number 313 is selected from

appendix table 3.



4.4 Cost analysis

The overall cost that we design for conveying purpose is as follow

Component Dimension material Quantity Price (in

birr)

Chain 22.04m Mild steel 2 2200

Sprocket Dia 650mm Mild steel 4 500

Shaft Dia 45x 1240mm

Dia 65x 1100mm

Mild steel 5 650

Bearing 209-

313-

Carbon

chromium

steel

10 1750

Key 11.25mmx7.5mmx51.4mm

16.25mmx5.4mmx23.7mm

Mild steel 6 300

Slats 250mmx1100mm Light metal 88 8800

Frame body 0.02x0.02x32m Cast iron

steel

1 1300

Nut and bolt M24 Mild steel 372 1116

Total cost 16616

Table 6: cost analysis of the project



Fig 16: roller conveying chain



Conclusions

After we joined in to wonji//shoa sugar factory for four months, we have gained many benefit

that concerning to our field what we have been learn in the class theoretically by seeing,

asking and operating some machine and part of increase our skill in many ways. So this

university-industrial linkage was prepared or conducting by department for engineering

student after taking some course will be bring student self relief and confidence to know what

they learn by theory and also opportunity to know what industry look like. When student join

in to factory and finding some problem occurred in the factory and give their proposed

solution for that problem was increase high quality productivity and give student to bring the

new idea and appreciate to discover the new machine. Therefore this course or internship is

important for student in term of student increase to link their theoretically knowledge with

practically.



Recommendation

Wonji/shoa sugar factory was the first sugar factory in Ethiopia that produce raw sugar, sugar

product and sugar by product for internal market and for export. This factory produces sugar

in high quality and also produces electric power from steam by itself. But we recommend

that, the WSSF factory is to

Produce steam by two pair of boiler rather than single boiler to increase power

generation

Decrease by air pollution by reducing the amount smoke released from the boiler

Increase the productivity per day as much as possible

Increase the efficiency of the turbine that produce electricity to 32MW

Give pocket money for student during internship

Additional plant like ethanol, work shop, i.e. and

Decrease the wastage of the steam by increase the efficiency of pipe flow.

Decrease the extravagance of lime during uptake from the land during for mixing.

Avoid improper ash drop in steam generation plant by increasing size of ash

conveying belt and making its coverage through which the ash is dropped.

Minimize bursting of steam pipe by using a pipe which can stand with high pressure

and temperature.



References

1) Hand book of cane sugar engineering. 3rd completely revised, edition

2) Cane sugar engineering, Peter Rein

3) Machine design –R_S_khurmi,kGupta text book

4) Strength of materials 4th. By Ferdinand l. Singer_Andrew Pytel

5) Shingley_s mechanical engineering design 8th edition

6) Fundamental of material science and engineering

7) Www. Roller conveying chain

8) Wonji/shoa sugar factory manual



Appendixes

Table 1 material selection

Component Material

Chain Mild steel

Sprockets Mild steel

Shaft Mild steel ( C-30)

Bearing Tin-based alloy

Supporting bar Mild steel

Nut and bolt Mild steel

Slat Light metal

Table 2: factor of safety (n) for roller and silent chains

Type

of

chain

Pitch

of

chain

in

mm

Speed of sprocket

50 200 400 600 800 1000 1200 1600 2000

Bush

roller

chain

2012-

15-25

7 7.8 8.55 9.35 10.2 11 11.7 13.2 14.5

30-35 7 8.2 9.35 10.3 11.7 12.9 14 16.3 -

30-35 7 8.5 10.2 13.2 14.8 16.5 19.5 - -

Silent

chain

12,7-

15.87

20 22.2 24.4 29 29 31.0 33.4 37.8 42.0

19.5-

25.4

20 23.4 26.7 30 33.4 36.8 40.0 46.5 53.5



Table 3: bearing selection

Bearing No. Bore (mm) Outside diameter (mm) Width

(mm)

206

306

406

30

62

72

90

16

19

23

207

307

407

35 72

80

110

17

21

25

208

308

408

40 80

90

110

18

23

27

209

309

409

45 85

100

120

19

25

29

210

310

410

50 90

110

130

20

27

31

211

311

411

55 100

120

140

21

29

33

212

312

412

60 110

130

150

21

29

33

213

313

413

65 120

140

160

22

31

35



Table 4: ultimate tensile strength and yield strength

Material Ultimate tensile

Strength, N/mm2

Yield strength,

N/mm2

Plain carbon steels

C 07

C 10

C15

C20

C25

C30

C40

C45

C50

40 Ni 3

30 Ni4 Crl

40 Cr 3 Mol V20

40 Crl

320 - 400

340 - 420

370 - 490

440 - 520

460 - 550

500 - 600

580 - 680

600 - 750

660 - 780

750 - 1050

1000 - 1150

1350

700 – 850

200

210

240

260

280

300

330

380

380

600

600

1120

540

Table 5: The recommended value of the kb and kt

Nature of loading Kb Kt

Stationary shaft

Stationary applied load

Suddenly applied load

Revolving shaft

Suddenly applied load

Minor shock load

Heavy shock load

1

1.5-2.0

1.5

1.5-2.0

2.0-3.0

1

1.5-2.0

1

1-1.5

1.5-3.0

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CHAPTER 1 · 2018-07-12 · JIMMA UNIVERSITY (JIT) SCHOOL Of MECHANICAL ENGINEERING 2015GC FINAL...

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