Project Report ECL

7/30/2019 Project Report ECL

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ACKNOWLEDGEMENT

I feel immense pleasure and privilege to express my deep sense of gratitude and

thankfulness towards all the respected persons ofECL,Haldia Works,who have helped,

inspired and encouraged by spending a lot of precious time with me and they have

made me an even more experienced person.

Firstly,I would like to thank Mr.Piyush Karnti Khila,senior executive HR Manager of

ECL,Haldia Works for his constant effort during the training period.Next I would like to

thank Mr.Soubhik Dutta Gupta,Senior Manager P&A, Mr. Abhishek

Dasgupta,Deputy manager P&IR, Mr. Pradip Kr Singh,Manager,Mechanical,COP

and Mr. Barun Behera,Assit. manager ,SIP and Debabrata Mondal,Nishit Majee

,G.N Das of PowerPlant unit who were in charge for their selfless and constant effort

during the preparation of trainining report.Lastly,I would like to thank the workers and

staff members for their relentless co-operation in explaining the details of the various

processes of the industry.

In the preparation of training report I would like to express my sincere gratitude to Assit.

Prof. T.K.Jana,Head,Mechanical Engg. Department,HIT,who had issued the letter to

the organisation as desired by me.


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COMPANYS PROFILE

Growing from strength to strength over half a century, Electrosteel Castings Limited isinspired by a strong legacy and motivated by the vision to remain world-class through a

focus on quality products and quality services. Today the Company is Indias leadingpipeline solution provider. It has a strong brand presence around the globe and has oneprevailing aim - to remain the first choice in the market segment by becoming aninternational benchmark. Thus, for Electrosteel, Carrying life to people, safe drinkingwater for all is not just a statement of an operational target but also the commitmentof a greater responsibility.

Electrosteel has to its distinction, many pioneering "first".

It is the first to set up a Ductile Iron Pipe Plant in India. It was the first to manufacture Grinding Media in India. It was the first to introduce Hi-Chrome technology to India for

Cement Plant Ball Mill Internals. It has been a pioneer in the manufacture of Alloy Steel Castings

in India.

Driven by Technology:

Always alert and sensitive about the importance of quality, Electrosteel seeks to presentvalue-added propositions to all customers. It has geared itself by facilitating advancedR&D activities in every area of application to develop best engineered products.Electrosteel has been recognised by numerous national and international agenciesworking on the public health system for dedicated process orientation and best practicemeasures in every area of operation.

Manufacturing Facilities:

The Companys first manufacturing facility at Khardah is now into production of DuctileIron Pipes, DI Fittings and Pig Iron. CI spun pipes are now manufactured at theCompany facility in Elavur (Tamil Nadu) while Low Ash Metallurgical Coke (LAMC) and

Sponge Iron are produced at the Industrial Unit at Haldia (West Bengal).

Global Presence :

Apart from meeting the growing demand for DI Pipes in India successfully, Electrosteelhas established a strong foothold in the international markets. It caters to a largecustomer base in 35 countries spread across the Indian subcontinent, South East Asia


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2.

2.1 Introduction

2.2 Sponge Iron Properties

2.3 Raw Materials

2.4 Process Flow Sheet

2.5 Process Description

2.5.1 Stock House

2.5.2 Rotary Kiln

2.5.3 Rotary Cooler

2.5.4 Product House

2.5.5 Bag Filter

2.5.6 After Burning Chamber

2.5.7 Gas Conditioning Tower

2.5.8 Electrostatic Precipitator

2.5.9 Intermediate Bin

2.6 FeT Test

3.1 Introduction

3.2 Flow Chart

3.3 Process Description


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1.1 Formation of coal:

The generally accepted theory of coal formation is that coal is the result ofgeologic processes occurring over long periods of time to dead plant matter.Most coal formation began in the coal-bearing period when large tracts ofswampland formed across much of the world.

The different stages for formation of coal are as follows:

Plant(woods)

Peat

Lignite

BrownCoal

Sub Bituminous

SemiAnthraciteAnthraciteGraphite.

1.2 Coal properties:

Coal comes in four different forms which differ in the content of different physicalproperties such as ash content,moisture content,volatile matter content & fixed carbon.

1.2.1 Moisture:

Moisture is an important property of coal, as all coals are mined wet. Groundwater andother extraneous moisture is known as adventitious moisture and is readily evaporated.Moisture held within the coal itself is known as inherent moisture and is analysed

quantitatively. Moisture may occur in four possible forms within coal :

Surface moisture: water held on the surface of coal particles or macerals. Hydroscopic moisture: water held by capillary action within the

microfractures of the coal. Decomposition moisture: water held within the coal's decomposed

organic compounds. Mineral moisture: water which comprises part of the crystal structure of

hydrous silicates such as clays.


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1.2.2 Volatile Matter:

Volatile matter in coal refers to the components of coal, except for moisture, which areliberated at high temperature in the absence of air. This is usually a mixture of short and

long chain hydrocarbons, aromatic hydrocarbons and some sulfur. The volatile matter ofcoal is determined under rigidly controlled standards. In Australian and Britishlaboratories this involves heating the coal sample to 900 5 C (1650 10 F) for 10min.

1.2.3 Ash Content:

Ash content of coal is the non-combustible residue left after coal is burnt. It representsthe bulk mineral matter after carbon, oxygen, sulfur and water (including from clays) hasbeen driven off during combustion. Analysis is fairly straightforward, with the coal

thoroughly burnt and the ash material expressed as a percentage of the original weight.

1.2.4 Fixed Carbon:

The fixed carbon content of the coal is the carbon found in the material which is left aftervolatile materials are driven off. This differs from the ultimate carbon content of the coalbecause some carbon is lost in hydrocarbons with the volatiles. Fixed carbon is used asan estimate of the amount of coke that will be yielded from a sample of coal. Fixedcarbon is determined by removing the mass of volatiles determined by the volatility test,above, from the original mass of the coal sample.


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1.4 Process Description:

The cokemaking process involves carbonization of coal to high temperatures (1100C)in an oxygen deficient atmosphere in order to concentrate the carbon. The commercial

cokemaking process can be broken down into two categories: a) By-productCokemaking and b) Non-Recovery/Heat Recovery Cokemaking. A brief description ofeach coking process is presented here.

a) By-product Coke production :

The entire cokemaking operation is comprised of the following steps: Beforecarbonization, the selected coals from specific mines are blended, pulverized, and oiledfor proper bulk density control. The blended coal is charged into a number of slot typeovens wherein each oven shares a common heating flue with the adjacent oven. Coal is

carbonized in a reducing atmosphere and the off-gas is collected and sent to the by-product plant where various by-products are recovered. Hence, this process is calledby-product cokemaking.

Figure 1: "Coke Side" of a By-Product Coke Oven Battery. The oven has just been "pushed" andrailroad car is full of incandescent coke that will now be taken to the "quench station".


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b) Non-Recovery/Heat Recovery Coke Production:

In Non-Recovery coke plants, originally referred to as beehive ovens, the coal iscarbonized in large oven chambers.The carbonization process takes place from the top

by radiant heat transfer and from the bottom by conduction of heat through the solefloor. Primary air for combustion is introduced into the oven chamber through severalports located above the charge level in both pusher and coke side doors of the oven.Partially combusted gases exit the top chamber through "down comer" passages in theoven wall and enter the sole flue, thereby heating the sole of the oven. Combustedgases collect in a common tunnel and exit via a stack which creates a natural draft inthe oven. Since the by-products are not recovered, the process is called Non-Recoverycokemaking. In one case, the waste gas exits into a waste heat recovery boiler whichconverts the excess heat into steam for power generation; hence, the process is calledHeat Recovery cokemaking.

Considering the heat recovery coke oven observed in ECL,it consists of four batteries.Each battery consists of two blocks. Each block contains seventeen coke ovens.

1.4.1 Coal Blending:

Blending is largely a mechanical process.It essentialy involves the mixing of goodquality coal having low ash content with poor quality coal having low ash content withpoor quality coal having high ash content so that the aggregate mixture has an ashcontent of less than 34%.This blending can be done either at the pithead.

1.4.2 Crushing of coal:

Crushing of coal is done in two processes:

a) Primary crushing:

After the blend has been formed, the coal mixture is sent to the primary crusher throughthe coal feed hopper.For ECL,the total no. of particles attains the basic size of 3mm.This is the avg. size of the particles required for coking in the coke oven.

b) Secondary crushing:

It involves further crushing of coal mixture after it has gone through primarycrushing.This results in 95% of the total aggregate attaining the net basic size of 3mmrequired for coking.


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1.4.3 Water adding point:

Water is added to the blended,crushed coal in order to allow the formation of coke forcarbonization.

1.4.4 Stamp Charging:

It basically involves formation of a stable cake with finely crushed coal(95%,-3mm) bymechanically stamping(hydrolic pressure 125 bar) outside the oven and pushing thecake thus formed inside the oven for carbonization. Coal moisture is maintained at 8-10% for the cake formation. Due to stamping,bulk density increases by 30-35%.

1.4.5 Quenching:

After coke pushing into quenching car the coke is transported for wet quenching, whereit is cooled to the temperature about 180-250C. Wet coke quenching assumes sprayingover burning coke of water in special facility - quenching tower. It is very important toguarantee constant humidity of cooled coke.

1.4.6 Coke cutter for sizing:

This process is implemented to cut and size the lump coke into the required size.Thecoke size required by ECL is 70-25mm(B.F coke).From the quenching station, lump

coke in the quenching car is pushed into the hopper by the stationary pusher.Then it isconveyed by the belt conveyor to the coke cutter for sizing.

1.4.7 Screening:

The sized coke is screened using 70mm screen and 25mm screen respectively. Thecoke of +70mm to +25mm is the B.F coke.Undersize of 25mm screen coke is screenedin the rotary screen. In rotary screen 6mm and 25mm is screened there.

From the screen house three types of coke are obtained:

B.F coke: 25mm to 70mm(stored in the coke bunker) Pearl coke: 6mm to 25mm Dust coke: 0 to 6mm


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1.5 Quality Assurance Parameters:

Quality parameters for the coking coal are analysed as follows:

Proximate Analysis

a) Moisture content.

b) Ash content.

c) Volatile Matter content.

d) Fixed carbon content.

The objective of the proximate analysis is to determine the moisture content, ashcontent, volatile matter content and fixed carbon content within the coal sample.This aremeasured in weight percent.

Air-dried basis neglects the presence of moistures other than inherent moisture whiledry basis leaves out all moisture including surface moisture and inherent moisture. Dry

Ash Free basis helps to determine the ash content in coal. Dry Mineral Matter Freebasis helps to determine the mineral matters present in the coal.

CSN(Crucible Swelling Number):

This term is used to determine whether the coal is coking or non-coking.

1 gm of crushed coal is taken in a crucible at a uniform level. It is then charged to amuffle furnace for 2.5 minutes at a temperature of 800

0C. The coal powder swells and

gains a shape from which the type of coal is determined.

CRI-CSR(Coke Reactivity Index and Coke Strength after

Reaction):

200 gm of coal balls is put in the basket inside the vessel. Then we put thethermocouple over the vessel and tightened the screws. We set the furnacetemperature to 11500C which is recorded by the safety controller. Then N2 gas ispassed through the furnace to inert atmosphere. The vessel is then put into the furnace. The temperature reduces to a certain extent due to heat exchange and then recovers,when main controller records 11000C, which is the temperature of the vessel as shownby the thermocouple. N2 gas is passed for a period of 15 minutes after that N2 flow isstopped. This time is called the Soaking Time. Then cylinder flow is opened and a


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Sponge Iron:

Direct-reduced iron (DRI), also called sponge iron, is produced from direct reduction ofiron ore(in the form of lumps, pellets or fines) by a reducing gas produced from natural

gas or coal. The reducing gas is a mixture majority of Hydrogen(H 2) and CarbonMonoxide(CO) which acts as reducing agent. This process of directly reducing the ironore in solid form by reducing gases is called direct reduction.

2.2 Sponge Iron properties: The iron ore mostly in the name ofHaematite and Magnetite are found on earth in oxide form. High

grade ore can contain more than 27% oxygen in oxide form. This oxygen is removed.

in solid reduction. When oxygen combines with gaseous reductants, leaves the iron

surface, creating number of micro holes of cavities in solid. The term sponge ironjustifies due to spongy appearance of porous solid. Iron ore is not attracted by magnets.Composition of iron ore are as follows:

Fe,

O2++

,

SiO2, Al2O3,

CaO, O2 Fe

MgO,

Pb,Cu,

Zn, V,

Gangue S,

P, Gangue:SiO2,Al2O3,CaO,MgO,Pb,Cu,Zn,V,S,P.LOI

++ Trace element:Pb,Cu,Zn,V.

During reduction reaction only O2 and LOI are removed from Ore body. The Iron oxide(Fe2O3) during reduction is converted to metallic Fe which is turned into solid state assponge and shows highly magnetic property.

Other properties of sponge iron are as follows:

Sponge Fe contains low O2 and Feo. It is attracted by magnet. It looks black with metallic lectures. Highly reactive with moisture.


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2.3 Raw materials: mainly used raw materials for the production ofsponge iron are as follows:

Non coking coal(Must have low ash content and non stickyin nature).

Iron ore. (different grades mostly Haematite). Dolomite(MgCO3,CaCO3).


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2.4 Process Flow Sheet:

Sized Coal,Iron

ore &

Dolomite

Rotary Cooler

I Bin

Product House

(for storing

mixture or sponge

iron and char)

Screen

Magnetic Separator

Sponge Iron

G

C

T

Waste Heat

Boiler

E

S

P

Power

Plant

Unit

Non Coking Coal

Iron Ore (Hematite)

Dolomite

Crusher

Crusher

Crusher

Screen

Screen

Screen

T7 (Fine coals

are injected)

Belt Conveyer

T2 T4

T1 T3 T5

A

B

C

Chamber

Rotary Kiln

T6

Fans

Water

Char

Coarse

Fines

Different Temp. Zones

Sponge Iron

Plant (SIP)

Bag

Filterand

chimney


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2.5Process Description:

Different types of non coking coals are first stored in bunkers and send through

the coal hopper to the crushing section and screened to obtain particles of

desired size range.

a) Feed Coal +8 to -20 mm

b) Coarse Coal +4 to -8 mm

c) Fine Coal +0 to -4 mm

Iron ore is sent to crushing unit (jaw crusher) for crushing operation and thenscreened through a 20 mm and 5 mm size screen to get iron ores of desired size.

Dolomite is sent through hopper by using conveyer belt system.

Coal, Iron and dolomite of desired size are mixed together and charged to rotarykiln which is slightly inclined. In rotary kiln haematite is reduced to sponge iron. Here sufficient air is supplied

to maintain the temperature of the reaction with the help of fans. Temperature ismaintained around 1100

0C. Fine coals are injected at the outlet of kiln to provide

sufficient carbon at the time of burning. Hot mix of sponge iron (FeO+Fe) and char is sent through a rotary cooler to

reduce temperature to1500C.

Dust particles from the mixture are removed by bag filter. Then the mixture is sent to the product house where mixture is sent through

magnetic separator which separates char from magnetic particles (sponge iron). Final product is screened to get lump and fine irons.

Waste hot gases containing the dust particles from the rotary kiln are burned in an

ABC(after burning chamber), where some dust particles tickles down and rest are

carried to gas conditioning tower (GCT) where the gas are cooled. Then dust particles are separated from gas in an ESP (Electro static precipitator)

by ionizing the dust particle and the gas is discharged through chimney. If GCT is not used, waste heat recovery boiler is used to recover heat from hot

gas stream and turbine generates the power. The condenser condenses the hotgas containing the dust particles and sent through ESP to remove dust and gasis discharged through the chimney.


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2.5.1 Stock House:

Raw materials are generally stored in stock house. Then they charged to crusher where

jaw crushers are mainly used for crushing operation. Crushed materials are screened

and oversize materials are crushed again to obtain particles of desired size range.ForCoal size range is (0-4 mm, 4-8 mm, 8-20 mm). For iron ore size range is (5-20 mm).

2.5.2 Rotary Kiln:

The kiln is a cylindrical vessel, inclined slightly to the horizontal, which is rotated slowly

about its axis. The material to be processed is fed into the upper end of the cylinder. As

the kiln rotates, material gradually moves down towards the lower end, and may

undergo a certain amount of stirring and mixing. Hot gases pass along the kiln,

sometimes in the same direction as the process material (co-current), but usually in theopposite direction (counter-current). The hot gases may be generated in an external

furnace, or may be generated by a flame inside the kiln. Such a flame is projected from

a burner-pipe (or "firing pipe") which acts like a large bunsen burner. The fuel for this

may be gas, oil or pulverized coal.

It is divided in seven temperature zones .For complete combustion O2 is added through

a fan per each zone. Thermocouple is present in each zone to measure the

tempera

tures.

Tempprofile in

the

rotary

kiln is

maintain

ed as follows:

The first section , approximately half of kiln is called preheating zone where

iron ore , coal and dolomite are dried and heated to reaction temperature using heat

released from the combustion of volatile matter and carbon in the coal.

The second half of the kiln is called reduction zone where major amount of O2 contained

in the iron ore is removed leaving metallic iron (Fe).Desulphurisation in the rotary kiln is

effected by calcined limestone or dolomite.

Temperature

T1

T2 T3 T4 T5 T6 T7

Reaction 750 860 960 1020 1020 1030 030Gas 930 1030 1080 1080 1090 1100Bed 850 980 1020 1030 1040 1050


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The chemical reaction taking place at different zones in the rotary kiln is

given below:

C+O2 CO2

CaCO3 CaO+CO2,

MgCO3 MgO+CO2,

C+CO2 2CO,

3Fe2O3+3CO 2Fe3O4+3CO2,

Fe3O4+CO 3FeO+3CO2,

FeO+CO Fe+CO2,FeS+CaO FeO+CaS;

Control of process Parameter:

In the operation of rotary kiln for direct reduction the important process parameters

which require close maintaining and control are as follows:-

Air profile.

Temperature profile. Kiln revolution.

Gas pressure in the kiln.

Cooler discharge temperature.

Coal injection.

Mean particle size.

Reaction time.


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2.5.3 Rotary Cooler:

Sectional Coolers essentially exist of a turning rotor which is mostly driven via chain. At

the ends of the rotor are stiff cases

for product feed and outlet. Depending on the size of the cooler the rotor is pivoted

either at the ends of its own shaft (shaft cooler) or is supported on running treads, as it

is typical for rotary drums. The interior of the rotor exists of several section-shaped

chambers which are arranged like cake pieces around a central hollow shaft. This

arrangement is completely surround by a water shell. According to requirements

Sectional Cooler are built with diameters between 0.8 and 4 m and lengths from 3 to 30

m.

Sectional Coolers work with indirect water cooling. Water is sprayed in the outer surface

of rotary cooler or can be given inside of shell. The product which is to cool usually falls

directly into the product feed housing. By the rotary movement and the conveyor

elements the product is conveyed to other end of the cooler. The rotation causes a

permanent mixing of the product in the chambers and hence a good heat transfer.

The sponge iron after reduction in rotary kiln is at 10500C is discharged to cooler where

the hot mixture loses its temp. from 8500C to 130

0C within a span of two hours. The

product at this stage is highly contaminated with char, dolomite and sponge iron fines.


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Rotary Cooler

2.5.4 Product House:

Products from the rotary cooler are carried through the conveyor belt system to the

product house. Firstly, products are stored here and then the magnetic separator

separates the DRI of different size range are separated by screening as for requirementand stored at bin.

2.5.5 Bag Filter:

It is one type of Filtration technique Commonly known as bag houses, fabric collectorsuse filtration to separate dust particulates from dusty gases. They are one of the mostefficient and cost effective types of dust collectors available and can achieve acollection efficiency of more than 99% for very fine particulates.

Dust-laden gases enter the bag house and pass through fabric bags that act as filters.The bags can be of woven or felted cotton, synthetic, or glass-fiber material in either atube or envelope shape.

The high efficiency of these collectors is due to the dust cake formed on the surfaces ofthe bags. The fabric primarily provides a surface on which dust particulates collectthrough the following four mechanisms:

Inertial collection - Dust particles strike the fibers placed perpendicular to thegas-flow direction instead of changing direction with the gas stream.

Interception - Particles that do not cross the fluid streamlines come in contactwith fibers because of the fiber size.

Brownian movement - Submicrometre particles are diffused, increasing theprobability of contact between the particles and collecting surfaces.

Electrostatic forces - The presence of an electrostatic charge on the particlesand the filter can increase dust capture.


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A combination of these mechanisms results in formation of the dust cake on the filter,which eventually increases the resistance to gas flow. The filter must be cleaned

periodically.

Types of bag houses:As classified by cleaning method, three common types of baghouses are:

Mechanical shaker:

In mechanical-shaker baghouses, tubular filter bags are fastened onto a cell plate at the

bottom of the baghouse and suspended from horizontal beams at the top. Dirty gasenters the bottom of the baghouse and passes through the filter, and the dust collectson the inside surface of the bags.

Cleaning a mechanical-shaker baghouse is accomplished by shaking the top horizontalbar from which the bags are suspended. Vibration produced by a motor-driven shaft andcam creates waves in the bags to shake off the dust cake.

Shaker baghouses range in size from small, handshaker devices to large,compartmentalized units. They can operate intermittently or continuously. Intermittentunits can be used when processes operate on a batch basis-when a batch is

completed, the baghouse can be cleaned. Continuous processes usecompartmentalized baghouses; when one compartment is being cleaned, the airflowcan be diverted to other compartments.

In shaker baghouses, there must be no positive pressure inside the bags during theshake cycle. Pressures as low as 0.02 in. wg can interfere with cleaning.


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The air to cloth ratio for shaker baghouses is relatively low, hence the spacerequirements are quite high. However, because of the simplicity of design, they arepopular in the minerals processing industry.

Reverse air:

In reverse-air baghouses, the bags are fastened onto a cell plate at the bottom of thebaghouse and suspended from an adjustable hanger frame at the top. Dirty gas flownormally enters the baghouse and passes through the bag from the inside, and the dustcollects on the inside of the bags.

Reverse-air baghouses are compartmentalized to allow continuous operation. Before a

cleaning cycle begins, filtration is stopped in the compartment to be cleaned. Bags arecleaned by injecting clean air into the dust collector in a reverse direction, whichpressurizes the compartment. The pressure makes the bags collapse partially, causingthe dust cake to crack and fall into the hopper below. At the end of the cleaning cycle,reverse airflow is discontinued, and the compartment is returned to the main stream.

The flow of the dirty gas helps maintain the shape of the bag. However, to prevent totalcollapse and fabric chafing during the cleaning cycle, rigid rings are sewn into the bagsat intervals.

Space requirements for a reverse-air baghouse are comparable to those of a shaker

baghouse; however, maintenance needs are somewhat greater.


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Reverse jet:

In reverse-pulse-jet baghouses, individual bags are supported by a metal cage, which isfastened onto a cell plate at the top of the baghouse. Dirty gas enters from the bottom ofthe baghouse and flows from outside to inside the bags. The metal cage preventscollapse of the bag.

Bags are cleaned by a short burst of compressed air injected through a commonmanifold over a row of bags. The compressed air is accelerated by a venturi nozzlemounted at the reverse-jet baghouse top of the bag. Since the duration of thecompressed-air burst is short (0.1s), it acts as a rapidly moving air bubble, travelingthrough the entire length of the bag and causing the bag surfaces to flex. This flexing ofthe bags breaks the dust cake, and the dislodged dust falls into a storage hopper below.

Reverse-pulse-jet dust collectors can be operated continuously and cleaned withoutinterruption of flow because the burst of compressed air is very small compared with thetotal volume of dusty air through the collector. Because of this continuous-cleaningfeature, reverse-jet dust collectors are usually not compartmentalized.

The short cleaning cycle of reverse-jet collectors reduces recirculation and redeposit ofdust. These collectors provide more complete cleaning and reconditioning of bags thanshaker or reverse-air cleaning methods. Also, the continuous-cleaning feature allowsthem to operate at higher air-to-cloth ratios, so the space requirements are lower.

This cleaning system works with the help of digital sequential timer attached to thefabric filter. this timer indicates the solenoid valve to inject the air to the blow pipe.


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Baghouse Performance:

Baghouse performance is contingent upon inlet and outlet gas temperature, pressuredrop, opacity, and gas velocity. The chemical composition, moisture, acid dew point,

and particle loading and size distribution of the gas stream are essential factors as well.

Gas Temperature - Fabrics are designed to operate within a certain range oftemperature. Fluctuation outside of these limits even for a small period of time,can weaken, damage, or ruin the bags.

Pressure Drops - Baghouses operate most effectively within a certain pressuredrop range. This spectrum is based on a specific gas volumetric flow rate.

Opacity - Opacity measures the quantity of light scattering that occurs as a resultof the particles in a gas stream. Opacity is not an exact measurement of theconcentration of particles; however, it is a good indicator of the amount of dustleaving the baghouse.

Gas Volumetric Flow Rate - Baghouses are created to accommodate a rangeof gas flows. An increase in gas flow rates causes an increase in operatingpressure drop and air-to-cloth ratio. These increases require the baghouse towork more strenuously, resulting in more frequent cleanings and high particlevelocity, two factors that shorten bag life.


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2.5.6 After Burning Chamber:

In After Burning Chamber(ABC) combustible constituents of exhaust gases from rotarykiln comprising after burning the exhaust gases from the rotary kiln are burned at atemperature above their ignition temperature in an ABC and supplying O2 containinggases to said ABC, the improvement comprising burning part of combustibleconstituents in each of plurality of series connected stages in the gases which is aboutto enter each succeeding stage by injecting water to a temperature above the ignitiontemperature of the entrained fine particle.


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2.5.8 Electrostatic Precipitator:

Electrostatic precipitators use electrostatic forces to separate dust particles fromexhaust gases. A number of high-voltage, direct-current discharge electrodes are

placed between grounded collecting electrodes. The contaminated gases flow throughthe passage formed by the discharge and collecting electrodes. Electrostaticprecipitators operate on the same principle as home "Ionic" air purifiers.

The airborne particles receive a negative charge as they pass through the ionized fieldbetween the electrodes. These charged particles are then attracted to a grounded orpositively charged electrode and adhere to it.

The collected material on the electrodes is removed by rapping or vibrating thecollecting electrodes either continuously or at a predetermined interval. Cleaning aprecipitator can usually be done without interrupting the airflow.

The four main components of all electrostatic precipitators are-

Power supply unit, to provide high-voltage DC power. Ionizing section, to impart a charge to particulates in the gas stream. A means of removing the collected particulates. A housing to enclose the precipitator zone.

The following factors affect the efficiency of electrostaticprecipitators:

Larger collection-surface areas and lower gas-flow rates increase efficiencybecause of the increased time available for electrical activity to treat the dustparticles.

An increase in the dust-particle migration velocity to the collecting electrodesincreases efficiency. The migration velocity

can be increased by- Decreasing the gas viscosity. Increasing the gas temperature. Increasing the voltage field.

Types of precipitators:

There are two main types of precipitators:

High-voltage,single-stage - Single-stage precipitators combine an ionizationand a collection step. They are commonly referred to as Cottrell precipitators.


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Calculation:

% Fe= Burette reading * f / sample weight.

where,f= strength of K2Cr2O7 .

4.1 Introduction:ECL Haldia, generates a power of 12MW. The governing principle of power generationis the fluid energy(DM Water)is converted to thermal energy(boiler steam is generated)which is further converted to mechanical energy(boiler steam rotates the blades of theturbine) and then finally to electrical energy(generator coupled with turbine). 2MWpower is consumed by the plant itself and 10MW power is sold to the W.B.S.E.D.C.L.

4.3 Process Description:

Water from the DM plant enters the deaerator. The deaerator is used to removedesolved O2 from the water. Then the deaerated water is sent to the boiler through theboiler feed pump. Steam is generated in the boiler which enters the turbine at480

0C,66kg/cm

2. The hot steam rotates the blade of the turbine at 3000 r.p.m and then

the pressure is reduce to zero.

As the hot steam rotates the blade of turbine at 3000 r.p.m,mechanical energy isconverted to electrical energy. Exciter converts the DC to AC . Voltage is generated bythe rotor which enables the generator to generate 12MW power.


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4.2 Flow Chart:


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6. BIBLIOGRAPHY

www.google.com

www.wikipedia.org

www.metalpass.com

www.jankicorp.com

www.freepatentsonline.com


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