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DEPARTMENT OF MECHANICAL ENGINEERING

MEHRAN UET JAMSHORO 

TRAINING PERIOD: 22-06-2015 TO 30-06-2015

DATE OF SUBMISSION: 30-06-2015

PRESENTED BY:Muhammad Anique (12ME117)

Internship Report

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ACKNOWLEDGEMENT

We feel immense pleasure to become a Trainee Internee of a huge and gigantic complex which produces one of the best quality Cement in Pakistan. Mr. Uzair from HR Department who welcomed us and gave presentation regarding the Complex i.e. M/s Lucky cement. His presentation covered all aspects of the Factory sections, his presentation was comprehensive, hence we did not find any difficulty while visiting the different areas of Complex. Mr. Azhar from Mechanical Department given us proper schedule for the internship. He was so supportive during our visit, he guided us for all the proper sections of mechanical at the complex.

I further want to thanks the people which have been mentioned below for their precious time and knowledge about their particular area .They have been the key individuals during our visit.

Mr. Wajid (Crusher Area)

• Mr.Asif (Kiln Area and Pyro Area)

Mr. Ashfaque Ahmed Khatri and Mr.Haris (vertical raw mill) Mr. Ahmed Ali Shah and Mr. Munawer (Cement and Packing Plant)

Overall, We Are Thankful To All the Officers and Workers of Lucky Cement Ltd.

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Abstract:

This report is being submitted at the end of 10 days internship program with M/s LUCKY CEMENT LTD. The report contains the knowledge of the different areas of interest and the process being involved in the manufacturing of cement products. This report has an overview of mechanism used during the working of tools and equipments. As I belong to the mechanical department therefore I have attached herewith pictures of machinery used in this gigantic complex.

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CONTENTS

1. CEMENT MANUFACTURING PROCESS

2. RAW MATERIAL USED

3. CRUSHER AREA

4. MECHANICAL CONVEYORS SYSTEM

5. VERTICAL RAW MILL

6. KILN

7. WASTAGE HEAT USED

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1. Cement Manufacturing Process:

The raw materials needed to produce cement (calcium carbonate, silica, alumina, and iron ore) are generally extracted from limestone rock, chalk, shale, or clay. These raw materials are won from the quarry by either extraction or blasting. The process for cement manufacturing in Lucky Cement used is Dry Process. These naturally occurring minerals are then crushed through a milling process. At this stage, additional minerals are added to ensure the correct chemical composition for making cement. These minerals can be obtained from the waste or by-products of other industries, such as paper ash. Milling produces a fine powder, known as raw meal, which is preheated and then sent to the kiln for further processing. The kiln is at the heart of the manufacturing process. Once inside the kiln, the raw meal is heated to around 1,500 degrees C. At this temperature, chemical reactions take place to form cement clinker, which contains hydraulic calcium silicates. In order to heat the materials to this very high temperature, a 2,000-degree C flame is required, which can be produced through the use of fossil and waste-derived fuels. The kiln itself is angled by 3 degrees to the horizontal to allow the material to pass through it, over a period of 20 to 30 minutes. A small amount of gypsum (3 percent to 5 percent) is added to the clinker to regulate how the cement will set. The mixture is then very finely ground to obtain "pure cement." During this phase, different mineral materials,

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called "additions," may be added alongside the gypsum. Used in varying proportions, these additions, which are of natural or industrial origin, give the cement specific properties, such as reduced permeability, greater resistance to sulfates and aggressive environments, improved workability, or higher-quality finishes.  Finally, the cement is stored in silos before being shipped in bulk or in bags to the sites where it will be used.

2. RAW MATERIAL USED :

i. Lime stone

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Lime stone is a sedimentary rock which has the formula CaCO3. Lime stone is an important stone for masonry and architecture work. It is the main component of cement.

ii. Bauxite Bauxite is the important aluminum ore. Its consist largely of minerals gibbsite AL(OH) 3 , hematite the clay mineral kaolinite etc.

iii. Clay Clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content. and which can be hardened when dried and/or fired. Clay deposits are mostly composed of clay minerals , minerals which impart plasticity and harden when fired and/or dried, and variable amounts of water trapped in the mineral structure by polar attraction

iv. Latrite Latrite is redish brown color and it contains iron content ,.It is less harder than gypsum but harder than limestone.

v. Gypsum Gypsum (Ca SO4)It is obtained from the N.W.F.P and 5% is added with clinker obtained from kiln in cement mill and then grinded to get cement. It is used for refreshness of cement.

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vi. Coal and tyre as afuel In lucky cement industry coal is the major source of fuel, for this purpose coal is imported from South Africa and indonesia. Lucky cement is also using scrap tyre as a fuel as calorific value of polymer is very good.

3. Crusher AreaIn lucky cement industry hammer crusher are used for crushing the limestone and coal. Coal crusher is also used sometimes for crushing clay. In lime stone crushing area first the big blocks limestone are dumped in a big hooper with the help of truck. And from there the blocks are feed into the feed roller with the help of an apron conveyor, is a type of conveyor made from individual apron plates that are linked together with hinges on its underside, thus creating a looped carrying surface where materials can be placed. It plays a vital part in cement industries by being used to move different heavy materials from one location to another. This type of conveyor is used to deliver a large number of materials across several phases of production and is particularly useful for transport of huge and heavy materials.The work of apron feeder is to slows velocity of the material and to protect the hammer and crusher from wear and tear. It has the vertical arrangement of belts and pulleys because it absorbs shock and horizontal arrangement may cause slip in belt. It has the toothed

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gear having sensors which is quiet helpful in stopping the feeder for the protection of crusher.

i. CRUSHER MECHANISM:

The crusher for limestone consists of multiple discs welded or joint together by any other means. Each disc has a five holes which contains shafts and each shaft contain 9 hammers it means that hammer crusher has 45 hammers. A hammer crusher has the different clearance are set between hammer and casing of crusher according to the requirement of size of finish. Usually we have 50, 100, 150 mm clearance. This Crushing machine reduces the size of large stones to approximate 25 mm to 35mm . From this the material is transferred to way feeder and storage house. The material from crusher transfer to storage house with the help of long belt of 400 m.

ii. STACKER AND RECLAIMER MECHANISM

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The Stacker can pile the material by moving 360 degree. There is a track for the motion of stacker on which the stacker can move which is motor driven. The boom of the stacker has the special mechanisms of slewing with the help of which it can move 360 degree. Reclaimer has the harrows which has needles in order to feed he material to bucket conveyor. Harrow of reclaimer are of two types one is hydraulic driven while the one has motor and chain driven which is used for coal and clay.Bucket conveyor has special type of conveyor which can move material in the conveyor to weigh tower with the help of bucket like mild steel. It is motor driven.

iii. WEIGH FEEDER

In weigh feeder there are four materials from different conveyors are storing in hooper. From there they are forwarded to chute which guide it to conveyor. The mixing of limestone, clay bauxite and latrite is fixed so the rpm of motors are fixed according to there fixed proportion. As lime stone is the basic and most used in percent in cement hence its rpm are greater than the

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other three. Here motor are gear and couple motors and wave conveyor are to protect loss of materials.

4.MECHANICAL CONVEYOR SYSTEMconveyor are basically a mechanical system used for the transporting of different types of Raw material , manufactured material etc.

Basically two types of mechanical conveyors are used:

1. Belt conveyor

2. Apron conveyor

The system comprises of mechanical transportation of different materials used in cement manufacturing . The process starts from the crushing area , where the crushed material is being transported through belt conveyor .This conveyor drops the material into hopers . After proper proportioning of material through weigh feeder, the material again transported to Raw mill through belt conveyor.

Apron conveyor are used where maximum load is carried out. Mostly apron conveyors are used in the crushers . when highly weighted load is dropped in the

hopers which was assigned with apron conveyor.

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5. RAW MILL AREAMaterial from weigh feeder is than brought through conveyor to the raw mill. Before raw mill the remaining course particles are also added in the conveyor before raw mill.Vertical raw mill is the most important part of cement manufacturing. It has a table which is motor driven having bevel gear box as the power is transmitted at 90 degree. In this the setting of mill is in vertical position. In raw mill we only rotate the table on which different numbers of rollers are placed which are not driven by any motor. When the table rotates than due to centrifugal force all the material goes away from the center and it grinds between the rollers and table. There is a layer of limestone intentionally present between rollers and tables. The rollers are attached with hydraulic arms in order to absorb the shock. They are attached to accumulator which supply the oil at right timing. Above the raw mill there is a fan called classifier is used in order to suck the fine particles and to ensure no heavy particle can goes upward and if there is course particles collide with the fan blade than it turn it back to raw mill. It has special heat treated blades as the shock load of course particles may damage the blades. There is a rotary valve at the inlet of raw mill which maintains the flow of feed. The hot air from preheater are also inlet into the raw mill to initially heat the raw material to remove moisture content in order to avoid wear and tear. It has a upthrust bearing at the bottom of table which is taper roller bearing.

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i. CYCLONES

Cyclone is a conical vessel into which a dust-bearing gas-stream is passed tangentially. The fine particles and hot air enter into the cyclones in which there is effect of cyclones due to which air and few dust particles enter into the system fan. There is also the rotary feeder in cyclones which controls the feed. Air is continuously pumped from down in the cyclones. The particles at the bottom are further transferred to air sliders. In lucky cement plant 4 cyclones are used in the VRM area which purify the hot gas which is coming from VRM .

ii. AIR SLIDES

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Air Slides is a mean of transportation in the cement plant it take the material from one place to another with the help of air. Bags and blowers are used in air slides. Air slides are normally used at the bottom of cyclones

iii. ID FAN

ID fan or induced drafts fans are used to supply hot air from preheater to raw mill. It also produces negative pressure in kiln.

iv. SYSTEM FAN

System fan is also an I.D fan but it is used for the suction of air from the Vertical Raw Mill through the cyclones. It sucks the hot air from the Vertical Raw Mill and send it to Bag house. It also works for maintaining the negative pressure into the Vertical Raw Mill.

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v. BAG HOUSE

Bag house is a collective name of many bag filters. Bag house has 20chambers and each chamber contains 114 bags. It is also known as dust collector or fabric filters. In lucky cement the most common type of bag filters are used which operates with a velocity of about 0.01 m/s across the bag surface. Bag house fan is a suction fan which helps the bag house in filtering the hot air from cyclones. If it does not work properly then there is a need to shutdown the plant because it also helps in producing the negative pressure and prevention of atmosphere from pollution.

vi. STORAGE OF GRINDED RAW MATERIAL

Homogenization of grinded raw materials the raw mix is stored in the silo that’s why its need to homogenize it for this purpose heavy compressor are used which throws air

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from the downward due to which a continuous motion occurs in the material and homogenization of grinded raw material takes place

6. KILN AREABefore the materials enters the kiln, it goes through a number of stages, like after being crushed the material consisting of limestone, litharge, clay enters the silo with the help of pneumatic system, as the material is in the form of powderImportant Stages before the KilnSilo before Pre heating tower:

The main function of silo is to store the raw material that is to be fed in the kiln through pre heating tower.The material is stored in it if the crusher, VRM or any other component fails we should have feeding for the kiln so that the production is not affected

There are two types of silo commonly used to store the material.

i) Blending Siloii) CF Silo

Lucky cement used CF silo to store the material, this type of silo mixes and blends the raw material with the help of air blowers that is installed beneath the silo. There are 8 air slides in the silo. The material passes from the bin to

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the shank through motorized valve. Motorized valve is used to check the feeding while the shank is used to control the feed to the pre heating towerBucket Elevator:

The bucket elevator is an important conveying system for the movement of the material from the silo to the pre heating tower. The bucket elevator consists of belts and buckets ranging from 380 to 450. The different portions of the belts are connected together through fastener joint. The fastener joint consist of steel plates on both the sides of the belts and connected together by nut and bolt.On the top of the Pre heating tower we have a motor connected to a gear box that is used to drive the belt and control its speed.Pre Heating Tower:

It is used to initially heat the powered material and to prepare it for feeding it in the kiln.The pre heating tower uses the hot gases produced in the kiln and hood to heat the powder. The hot gases are passed from hood to the pre heating through a tertiary duct passing above the kiln. Because of this we utilize the energy of the gases produced in the kiln instead of wasting them. These hot gases are further used after passing through the pre heater to the CT fan, coal fan etc. The kiln consists of four stages, each having feeders to control the material to be fed in the kiln through valves. The pre heating towers has alternating cyclones and

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risers. The risers are used to suck the air so that it can pass through the powder.

KILN

Simply kiln is type of a large oven used for baking or drying cement.Cement kilns are used for the pyro processing stage of cement manufacture. The materials from raw mill after passing from preheaters enter in kiln and are heated up to 1450 °C. The largest kilns today can produce around 10,000 tons per day.Kiln at Lucky Cement

65meter long Internal Diameter 4.3m 3.84° slope Rotation 4-5 rpm Capacity 3000tonns/day

 In kiln calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates. The capacity of kiln defines the capacity of plant in Lucky

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Cement CO. Raw mix is fed in at the upper end, and the rotation of the kiln causes it gradually to move downhill to the other end of the kiln. At the other end fuel, like oil, gas or coal is burned to produce a flame. As material moves under the flame, it reaches its peak temperature, before dropping out of the kiln tube into the cooler.Fans are also used at different positions to control the temperature of the shell especially near the burning zone.Sensors are used throughout the kiln to monitor the temperature around the kiln. Because of this we can observe bricks removal or fan failure. The brick failure can also be observed through naked eyes as the region becomes red hot.Thrust bearing are used to move the supporting rollers between a limit of 50mm so as to avoid the steps that can be produced under high stresses between roller and the cast iron tire.Cooling of clinker

In lucky cement grate type cooler is used having two main advantages i.e. rapid cooling of clinker that is necessary for quality and these coolers don’t rotate as early ones did so the air can be ducted out easily and can be used for better combustion. This cooler consists of a perforated grate through which cold air is blown enclosed in a rectangular chamber a bed of clinker up to 0.5m deep moves along the grate the grates are moved with the help of hydraulic system.At the end of cooler a crusher system is fixed that crushes chunks of clinker into a prefixed size. Then clinker is discharged from “discharge shoot” on to a pan

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conveyer. This clinker transport system transports clinker to clinker storage house.Hot gases from kiln are not wasted but are used to generate power. These hot gases are used in waste heat recovery boilers to generate steam and then steam is used to drive steam turbines to produce electric power.The Kiln ShellThe shell of the kiln is pasted inside with fire bricks tightly attached to another throughout the circumference because the inner temperature of the kiln ranges from 400 C to 1400 C. The material of the shell cannot sustain such high temperatures so we have to use ceramic bricks as refractory material.

Tyres and RollersThe purpose of tyres (often called riding rings) and rollers is to support the kiln and allow it to rotate with minimal friction. At lucky cement kiln rests on three rollers each station consists of two rollers. These rollers are supported by a shaft and half journal bearing, the temperature of these bearings is very important to be kept constant. A push tyre or thrust roller is also present at these stations which are used to translate the tyre on kiln linearly as to generate uniform stresses on rollers otherwise because of

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heavy load of kiln steps are formed on rollers at such stations.

The Kiln DriveA motor drives a reducer gear box assembly that is connected to a pinion gear through flexible coupling (shrimp coupling) to avoid radial and axial torques. The grith gear is connected with tangent plate because they act like spring and avoid the direct contact of kiln with gear.

Rotary kilns run 24 hours a day, and are typically stopped only for a few days once or twice a year for essential maintenance. One of the main maintenance works on rotary kilns is tyre and roller surface machining and grinding works which can be done while the kiln works in

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full operation at speeds up to 3.5 rpm. This is an important discipline, because heating up and cooling down are long, wasteful and damaging processes. Uninterrupted runs as long as 18 months have been achieved.

7. WASTE HEAT RECOVERY In lucky cement heat waste from the kiln is utilized in heating the boiler. From boiler the turbine is running making lucky cement’s own power resource. First the waste heat from kiln is send to boiler which has three section economizer, evaporator and superheated region. Boiler is eleven stages boiler. The heat is first added to economizer then to boiler heater and then to evaporator and again then to heater and again to super heater. From super heater the steam is transferred to turbine for production of electricity. The boiler is connected with a deaerator is a device that is widely used for the removal of oxygen and other dissolved gases from the feed water to steam-generating boilers. In particular, dissolved oxygen in boiler feed waters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides. Dissolved carbon dioxide combines with water to form carbonic acid that causes further corrosion.In turbine room there is turbine called impulse condensing turbine in which the steam is input radially

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and ejected axially. The turbine is supported by bearing and axial thrust bearing. Theses bearing are white metal bearing which need proper lubrication. There is system of oil filter and oil cooler in order to save wear and tear in bearings. It has hydraulic lever which could stop the supply of steam. Then the steam after striking with turbine blades condenses and is brought to absorption chamber where it is mixed with new cooled water and transferred to the cooling towers in order to condense the water. The water is provided to boiler from RO plant. The absorption chamber has tubes which condenses the steam.