Transcript
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A REPORT
ON
AT
ULTRA TECH CEMENT LI M ITED.
UNI T: KOTPUTLI CEMENT WORKS
Submitted to- SUBMITTED BY
H.R. MANAGER TARUN MATHUR
Kotputli Cement Works M.B.M. Engineering College
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ABSTRACT
Cement, as used in construction, is a fine powder which when mixed with water
and allowed to set and harden can join different components or members together
to give a mechanically strong structure. Portland cement is the most common type
of cement in general usage in many parts of the world for construction purposes, as
it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It
is a fine powder produced by grinding Portland cement clinker. The Portland
cement clinker is manufactured by igniting a finely ground mixture of lime bearing
material like CaCO3, clay, laterite in some predetermined proportions, cooling the
product of sintering. Grinding clinker by adding some proportion of gypsum, the
final product is called cement. The detailed description of each and every step in
the manufacture of cement is explained in the report. Also the equipment used in
every section, is explained in the report.
Cement manufacture involves grinding of clinker, gypsum, fly ash etc together.
For the manufacture of clinker raw materials should be burnt at high temperatures
of above 1400 degree Celsius in the kiln. To generate such large amounts of heat
fuels like coal, pet-coke or furnace oil are used. As these fuels are required in large
amounts, fuel costs play a major role in the operating costs of the cement plant. By
performing heat balance we can get specific heat consumption of the kiln, thereby
we can calculate approximate amount of fuel required. It also helps for stable
operation of kiln and optimization of kiln parameters. We can also study if thereare in any faults in the system from the calculations. The detailed description of
various terms in the heat balance calculations, procedure for heat balance,
necessary conditions and assumptions are explained in the report.
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ACKNOWLEDGEMENT
I am highly thankful to Solex Limited and Ultratech Cement Ltd--Kotputli forproviding me an opportunity to work in this industry and have such a great deal ofexposure to the cement industry. I would like to express my sincere gratitude to thefollowing people for their guidance and support:
Mr. Anil Vyas Sir,( HOD Chemical Engineering, M.B.M. College). Mr. B.R. Sharma Sir, (HOD Process). Mr. Sandeep Jalori Sir.(My mentor) Mr. Sitaram Sir.(Our instructor of solex limited)
And finally, I would like to thank every person of the staff who has helped medirectly or indirectly in the completion of my training.
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INTRODUCTION
ABOUT THE ADITYA BIRLA GROUP
A US $28 billion premium conglomerate, the Aditya Birla Group is in the league
of Fortune 500. It is anchored by an extraordinary force of 100,000 employees,
belonging to 25 different nationalities. In India, the Group has been adjudged The
Best Employer in India and among the top 20 in Asia by the Hewitt-Economic
Times and Wall Street Journal Study 2007. Over 50 percent of its revenues flow
from overseas operations.
The Group operates in 25 countries- India, UK, Germany, Hungary, Brazil, Italy,
France, Luxembourg, Switzerland, Australia, USA, Canada, Egypt, China,
Thailand, Laos, Indonesia, Philippines, Dubai, Singapore, Myanmar, Bangladesh,
Vietnam, Malaysia and Korea.
GLOBALLY THE ADI TYA BIRLA GROUP IS:
A metals powerhouse, among the worlds most cost-efficient aluminum and
copper producers.
No.1 in Viscose Staple Fibre
The 4
th
largest producer of insulators The 4
thlargest producer of carbon black
Among the worlds top 15 BPO companies
Among the most energy efficient fertilizer plants
Among the worlds top 10 cement producers
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IN INDIA:
The largest cement producer
A premier branded garments player
The 2nd
largest player in Viscose filament yarn
The 2nd
largest in Chlor- Alkali sector
Among the top 5 mobile telephony companies
A leading player in Life Insurance and Asset Management
Among the top 3 super-market chains in the Retail business
Rock solid in fundamentals, the Aditya Birla Group nurtures a culture where
success does not come in the way of the need to keep learning afresh, to
keep experimenting.
ULTRA TECH INDUSTRIES:
Ultra tech Industries Limited, a flagship company of the Aditya Birla
Group, ranks amongst Indias largest private sector companies, with
consolidated gross revenues of Rs. 148.33 billion and a consolidated net
profit of Rs.28 billion
Ultra techventured into the Cement production in the mid 1980s by setting
up its first plant at Khor in Madhya Pradesh. The merger of the Cement
business of Indian Rayon in 1988 and the acquisition of L&Ts Cementbusiness in 2004 catapulted the Aditya Birla Group to the top of the league
in India.
The Business has all its manufacturing locations in India except a packaging
and distribution operation in Sri Lanka which is part of Ultra Tech Cement
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Limited through its subsidiary, Ultra Tech Ceylino (Pvt.) Limited.
All plants are strategically located in the vicinity of sizeable limestone mines
and are fully automated to ensure consistent quality. All units employ state
of the art technology. All the cement units are certified with ISO 9001 for
quality systems, ISO 14001 for environment Management systems and
OHSAS 18001 Occupational Health and Safety Management System. Six of
its manufacturing locations are certified to SA 8000 Social Accountability
Standard
COMPOSITE PLANTS:
Vikram Cement, Jawad (MP)
Ultra tech Cement, Rawan (Chhattisgarh)
Aditya Cement, Shambhupura (Rajasthan)
Rajashree Cement, Malkhed (Karnataka)
UltraTech Cement, Reddipalayam (Tamil Nadu)
UltraTech Cement, Kotputli (Rajasthan)
UltraTech Cement, Awarpur (Maharashtra)
UltraTech Cement, Hirmi (Chattisgarh)
UltraTech Cement, Kovaya (Gujarat)
UltraTech Cement, Jafarbad (Gujarat)
UltraTech Cement, Tadipatri (AP)
Birla White, Kharia Khanghar (Rajasthan)
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GRINDING UNITS
Ultra tech Cement, Hotgi (Mahasrashtra)
Ultra tech Cement, Bhatinda (Punjab)
UltraTech Cement, Jharsuguda (Orissa)
UltraTech Cement, Durgapur (West Bengal)
UltraTech Cement, Arakkonam (TN)
UltraTech Cement, Magdala (Gujarat)
UltraTech Cement, Ratnagiri (Gujarat)
UltraTech Cement, Dadri (UP)
UltraTech Cement Aligarh (UP)
PRODUCTS
Clinker
Concrete
Various grades of Ordinary Portland Cement
Puzzolana Portland Cement
Sulphate resistant Cement
Portland Blast Furnace Slag Cement
White Cement
Wall Care Putty
BRANDS
UltraTechCement and Ready mix concret
Birla WhiteWhite Cement and its value added products etc
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UltraTech Cement, Kotputli
The date of announcement of UltraTech Cement, Kotputli Project was Friday, 31st
March, 2006. UltraTech Cement, Kotputli is a Greenfield project started in June
2006, under UltraTech Industries Ltd., of Aditya Birla Group having a capacity of
4.4 MTPA cement production. The cement plant is also equipped with Captive
Power Plant of 23*2 MW capacity. The Ultratech Cement, Kotputli is spread over
an area of 403.08 acre, and the mines area comprising of 888 acres of land.
Kotputli is located near Jaipur- Delhi Highway No.8.
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CEMENT
Cement can be defined as any substance which can join or unite two or more
pieces of some other substance together to form a unit mass.Cement, as used in
construction industries, is a fine powder which when mixed with water and
allowed to set and harden can join different components or members together to
give a mechanically strong structure.
The cements coming under the category of Portland cements are also known asHydraulic Cements, because they, when mixed with water, have the property of
setting and hardening under water.
PORTLAND CEMENTS
They are made by grinding a mixture of limestone and clay matter,
burning the mixture at a very high temperature, cooling the resultant product,
called Clinker, and grinding the same to an impalpable powder. Essential
constituents are lime, alumina, silica and iron oxide. Some gypsum is added in
the final grinding stages. Portland cement types are divided into seven classes,
but the method of manufacture is practically the same; they vary only in
chemical composition to impart desired properties.
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THE RANGE OF CHEMICAL COMPOSITION IS
SiO2 19-25%
Al2O3 2-8%
Fe2O3 0.3-6%
CaO 60-65%
MgO 1-6%
SO3 1-3%
Alkalies 0.5-1.5%
Table: Chemical Composition (Oxides) of clinker.
Portland cement types are essentially composed of Tricalcium Silicate
(C3S); Dicalcium Silicate (C2S), Tricalcium Aluminate (C3A) and Tertracalcium
Aluminoferrate (C4AF). Presence of more or less of the above constituents imparts
the different properties.
C3S 20-60%
C2S 20-60%
C3A 0-16%
C4AF 1-16%
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RAW MATERIALS
The main raw material used in the cement manufacturing process is limestone.Limestone is usually mined on site and most cement plants are located near thelimestone mines.
Other important raw materials are1. Clay
2. Red ochre
3. Laterite
Additives are also used for cement manufacture for improving properties ofcement.
1. Gypsum2. Fly ash
1. LIMESTONE :The chemical formula of limestone is CaCO3. It is mostly available in its purestform on the surface of the earth. When limestone is heated above 1100o C limeis formed,
CaCO3 CaO + CO2
This reaction is called Calcination reaction.
2. LATERITE :
It mainly comprises of non magnetic iron particles which acts as flux during theburning of raw material.
3. CLAY :
It contains silica particles required for clinker formation
4. RED OCHRE:
It is the main resource for alumina which again acts as flux material.
5. GYPSUM:
Its chemical formula is CaSO42H2O. It is used as additive during the grindingof clinker. The main advantage of gypsum is that it increases the setting time ofcement when it is mixed with water.
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6. FLY ASH: It is the additive used during the manufacture PPC. It acts asartificial Pozzolana. PPC gives high long term strengths
SIGNIF ICANCE OF INGREDIENTS OF CEMENT
C3S (Alite): contributes to early strength. Low heat of hydration compared to
alite.
C2S (Belite): contributes to late strength. Low heat of hydration compared to
alite
C3ASets quickly and increases heat of hydration
C4AFImparts a dark colour to the cement
TYPES OF CEMENT MANUFACTURED AT KOTPUTLI CEMENT
PLANT:
Ordinary Portland Cement43 grade
Ordinary Portland cement53 Grade
Portland Pozzolana cement
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CEMENT MANUFACTURING PROCESS
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MINING
Mining is mostly required for limestone and clay. Most of the cement plants aresetup close to a limestone mines because it is the major raw material in the cement
manufacture so that major transport costs are reduced. Mining of limestonerequires the use of drilling and blasting techniques.
The process of mining includes three things:1. Prospecting: It is the process of finding potential place where very useful &
bulk quantity of limestone can be extracted.
2. Drilling: After providing with a better place for mining, the process ofdrilling takes place, in which the place is drilled with the drilling machines,for inserting the dynamites.
3. Blasting: After drilling holes, this place is blasted by blasting materialsinserted inside the drilled part to break the huge rocks into pieces.
The blasting techniques use the latest technology to insure vibration, dust, and
noise emissions are kept at a minimum. Blasting produces materials in a wide
range of sizes from approximately 1.5 meters in diameter to small particles less
than a few millimeters in diameter. Material is loaded at the blasting face into
trucks for transportation to the crushing plant.
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CRUSHING
Raw material from mines in bulk transported and dumped into the hopper of thecrusher. In the crusher, the limestone is reduced to a size less than 50 mm.
Impact Crusher
The details of the crusher used in this plant are as follows:Make: Larsen and Toubro LtdModel: APCM-2022Capacity: 1600 TPD (with Wobbler feeder)Feed size: ~1.5m diaSize of Product: 90% (-) 40mm
Double Rotor Impactor giving precise control over product size.
Equipped with Vibrating Screen and Wobbler Feeder enhancing Crusheroutput.
Crushing circuit:
Limestone from mines is transported through Dumpers and dumped into hopper ofthe crusher. In hopper the material falls on to an apron conveyor. Apron conveyortransports the material on to a wobbler feeder. The wobbler feeder separates -50mm sized particles present in the feed so that only large sized particles are sent forcrushing. From wobbler feeder material goes into the impact section. Crushing of
material takes place in this section. Size reduction of material takes place byimpact betweeni.) Blow bar and material
ii.) Material and material
iii.) Material and impact arms.
The crushed material will have a size
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RAW MATERIAL HANDLING
Intermediate storage of raw materials between quarry and the raw mill.Used as pre homogenization or pre-blending.
Capacity of stacker1600Tph
Capacity of reclaimer1200 Tph
i . STACKING :
The percentage of limestone in raw material which is quarried from the minesvaries because every part of the mine cannot have same amount of limestone
percentage everywhere. So at the stackers the limestone is homogenized by
arranging the raw material in proper stock piles before sent to raw mill for grinding
TYPES OF STACKER:
1. Slewing and luffing stacker> For coal.
2. Non slewing and luffing stacker-
> For limestone and additives.
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ii. RECLAIMERS:
Reclaimers are used for the transportation of raw material to the respective mill
hoppers. All the raw materials are stored in various stock piles and reclaimed
whenever required.
Machine which removes material from stockpiles.
Used for transportation of raw material to the raw mill hopper.
ADVANTAGES :-
Homogenizing of non-homogeneous material.
Better utilization of inhomogeneous raw materials deposits.
Pre blending of different raw material component is possible.
Better uniformity of raw mill and thus of the clinker, so quality of cement is
constant.
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RAW MATERIAL GRINDING
RAW MI LL HOPPERS
From stacks the raw material is transported to raw mill hoppers with the help ofreclaimers. In this plant there are 5 raw material hoppers of different capacities of
which 2 are for lime stone, 1 for clay and 2 metallic hoppers for laterite and red-ochre each.From here raw material is sent to raw mill where it is ground to very fine particles.
Desired proportions of the raw materials are sent to the mill by using weigh-
feeders. Weigh-feeders calculate the amount of each material from the percentage
of material specified to it. The proportion of raw mix is determined by the Quality
Control department of the plant. From weigh-feeders the material is transported
into raw mill through conveyor belts.
From stacks the raw material is transported to raw mill hoppers with the help
of reclaimers.
In our plant 5 raw mill hoppers are there, 2 for limestone and one each for
clay, laterite and red-ochre each.
From here desired proportions of raw material are send to the raw mill
through weigh feeders via conveyor belts.
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RAW MILL
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Process of raw mill
In our plant the equipment used for grinding in raw mill is vertical roller
mill.
The material from raw mill hopper comes to raw mill through conveyor belts Feed is introduces from the top on the grinding table.
Retention ring on the periphery forms the grinding bed.
Hot air from the bottom lifts the material to the classifier which is located at
the top of the mill
Classifier separates coarse and fine particles.
Fine product moves out of the classifier with the air discharge.
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BLENDING SILO
Known as BLENDING SILO
Capacity31200 MT
Height78.5 mtr
Diameter26 mtr
Last stage of homogenization
Used for storage of raw meal
There are 14 air slides at the top which carry the raw meal to the silo and 12
at the bottom to convey the material further to the pyro processs.
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COAL MILL
Imported Coal and Pet-coke are the main fuels used for burning purposes. Both ofthem are ground to fine powder in the coal mill. Petcoke is the industrial byproductof petroleum industries. It has very high calorific value around 8300kcal/kgcompared to coal. But the grinding of petcoke is difficult when compared to coal.Lot of heat is generated during grinding of petcoke so it is somewhat difficult
process. In India mostly coal is used as fuel. For burning of raw mix the ashcontent in the coal should be as less as possible because more ash% in coal affectsthe color of the cement becomes darker and affects the cementatious properties.In this plant VRM is used for fuel grinding.
Main points:
Main fuel used is imported coal and pet coke for burning purpose.
In coal mill, coal/ pet coke is grounded into fine coal for firing in precalciner
and kiln.
Coal mill also dry up the moisture in raw fuel through the heat of hot kiln
flue gases.
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Has one type of accumulatorBladder Type ( 4 in number) for handling the
operating pressure.
COAL MILL FLOW DIAGRAM
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PYROPROCESS
In the latest cement industries the pyroprocess consists of 3 sections:1. Preheater
2. Burning in a rotary kiln
3. Cooling of clinker formed
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Preheater:
Preheater is the latest technology used in the field of cement industry to
decrease the time of burning in the rotary kiln for the formation of clinker,
so that the production of Clinker is increased. A preheater is long verticaltower consisting of cyclone separators connected in series from top to
bottom and also precalcination tower is arranged as latest Development. For
the formation of clinker the raw mix should be burnt to a temperature of
above 1200oC. Without preheater it takes a long time to achieve this
temperature in the kiln making the retention time of material is very high
hence production of clinker is very low. But with the use of preheater, this
temperature is achieved very fast thereby increasing the production of
clinker to a large extent. Heating of material in preheater is done by hot exitgases of kiln and hot gases generated from cooler.
Make: KHD-GermanyType: 6-stage Preheater with calciner (2 strings)
Capacity: 10000 TPD
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Preheater Material Flow:
In preheater material is introduced from top and hot gases are blown from bottom.A draft fan placed after preheater tower creates suction and regulates the flow ofgas. The raw meal is normally introduced at the riser duct of stage (2)-(1). The
material is dispersed into the rising gas stream, ensuring an instantaneous heattransfer. Due to suction the material and the hot gases are lifted up into cyclonestage (1). Velocity in the riser duct is maintained in such a way that material is not
dropped down. In the cyclone air and material are separated and material leaves thecyclone from bottom cone. It flows through the material flap gate and is 26directed to riser duct of stage (3)-(2) and the process repeats. Major heat transfer
between material and hot gases takes place in the riser ducts. In this manner the
material passes step-wise through the cyclones while heat exchanging with the hot
gas.
From the cyclone stage (5) the material is directed to the calciner. The material willbe suspended in the gas while the calcination process takes place. This ensures an
excellent mixing and transfer of heat. From the calciner top the material and gas
enters the bottom cyclone stage i.e., stage (6) where material and gas are separated.
The exit of stage (6) is connected to the kiln inlet. The inlet temperature of material
entering kiln would be around 1100oC. Upon leaving the last stage the material
should normally have a degree of calcination of between 90-95%.
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KILN
Make : KHD
Length : 85 m
Diameter : 5.8 m
Speed :4.5 rpm
Specific heat consumption : 686 kcal /kg
Number of supporters : 3
Inclination : 3.5%
Function :to produce clinker
There are 4 zones
Calcination zone
Transition zone
Burning zone
Cooling zone
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CALCINATION ZONE:
Endothermic reaction.
In this calcium carbonate decomposes to form quick lime and carbon
dioxide. Temperature required is around 900 degrees Celsius.
In this zone calcination completes.
TRANSITION ZONE
Endothermic reaction
Temperature around 1200 degree Celsius.
Formation of belite, Tri calcium aluminate and Tetra calcium alumino ferrite
in this zone. Without the formation of fluxing reagents i.e. C3A, C4AF the formation of
alite would be slow and difficult.
CHEMICAL REACTIONS :-
2Cao + Sio2 C2S (2CaO.SiO2)
3CaO + Al2O3 C3A
4CaO + Al2O3 + Fe2O3 C4AF
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BURNING ZONE
Also known as HEATING ZONE.
Temperature is around 1300- 1450 degree Celsius.
Tri calcium silicate is formed.
process completes when all the silica is in C3S and C2S crystals and the
amount of free lime (CaO) is reduced to minimum level ( less than 1%).
CHEMICAL REACTIONS :-
COOLING ZONE
Cooling of clinker takes place in this zone by coolers.
Temperature of clinker is reduced to nearly 100 degree Celsius.
Cooling process influences clinker structure, composition grind ability, thus
quality of cement.
Rapid cooling increases sulphate resistance, prevents undesired chemical
reactions in clinker which may affect quality and grind ability.
These reactions happen at different temperatures in preheater and kiln. A glance ofclinkering reactions is given below:
i.) Up to 700oC: At 100oC free moisture in raw meal is removed due to evaporation.
400 C -500 C combined moisture is removed
Clay minerals are decomposed into their oxides (SiO2)
ii.) From 700-900 oC: Calcination continues, CaCO3 dissociates to CaO, free lime increases.
Calcination maintains feed temperature around 850oC.
Lower limited aluminate and ferrite form
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iii.) From 900-1150 oC :
Reactive Silica combines with CaO to begin formation of C2S.
iv.) From 1150-1200 oC :
Calcination is completed
Small belite crystals form from combination of silica and CaO.
v.) From 1250-1350 oC :
Above 1250C liquid phase is formed
Belite and CaO form Alite in the liquid
vi.) From 1350-1450 oC
C2S crystals decrease in number and increase in size C3S crystals increase in size and number
vii.) Cooling :
Upon cooling C3A & C4AF crystallize from liquid phase
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The raw meal enters the top of the kiln, which is slightly inclined
downwards. The material is transported through kiln by the combination ofkiln inclination and rotating movement. The kiln speed is normally
maintained around 4.5-5rpm. Kiln has 3 zones namely Calcination zone,
Burning zone and Cooling zone. In calcination zone total calcination
reaction is completed. The formed lime starts reacting with silica, alumina
and iron oxide to form clinker. In the burning zone the flame heats the raw
meal to 1400oC in order to complete the clinkerisation process, producing
clinker. The cooling zone is very small where the cooling and solidification
of formed clinker starts and material is directed into cooler for final cooling.
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COOLER
Cooling of clinker is essential before storage. A cooler is used for this purpose and
the temperature of clinker is reduced nearly to 100oC at cooler exit. In this plant a
pyrofloor cooler is used for cooling purpose. This is the most advanced clinker
cooler in the field of cement industry. In addition, rapid cooling prevents undesired
chemical reactions in the clinker which may negatively affect the quality and the
grind ability of the clinker.
Make : KHD Germany
Type : Pyro floor cooler
Dimensions : length- 47.8m,width4.09 m
Lanes7
Number of fans11
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In cooler there are lanes placed parallel to each other. Hot clinker from kiln
falls onto these lanes. The lanes move forward and backward in a systematic
way so that the clinker conveyed forward. Cool air is blown from the bottom
by the cooler fans. There are 10 cooler fans installed in this plant. As the
material moves forward cool air is blown from bottom and in this clinker is
cooled. The hot air generated after cooling the clinker is sucked into kiln and
TADs for further heating purposes in preheater, raw mill by the draft fans
placed after preheater exit. The exhaust gases are sucked by a cooler draft
fan and sent to electrostatic precipitator to separate dust from hot air before
sent into stack. The draft fan is placed after the exit of electro static
precipitator. The collected dust is again sent to clinker conveyor. Required
amount of air is sent into cement mills for heating purposes from the stack.
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CLINKER SILO
After cooling, the clinker turns into strong hard balls around 100-130oC. Thisclinker is sent to clinker silo for storage. Bag filters are arranged for the collectionof emitted dust during transportation into the silo.
Design : Peters Silo
Capacity: 1.5 Lac MT * 1 Silo
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CEMENT MI LL
MAKE: Loesche, Germany
SPECIFIC POWER CONSUMPTION : 40 kWh/T
MODEL : LM 53.3 +3 (VRM with 3 master and 3 slave rollers)
CAPACITY : 215 TPH
NUMBER OF MILLS : 2
FEED SIZE : 85%
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Clinker from silo is transported to cement mill hoppers. There are other hoppers
for gypsum, wet fly ash and dry fly ash which are used as additives during grinding
of clinker. Required proportions of materials is measured through weigh-feeders
and sent to the mill for grinding. Here also a vertical roller mill is used for grinding
of clinker. The grinding of clinker to cement is a dry grinding process. It is to be
noted that the temperature of clinker coming out of cooler may be near about
100oC and temperature doesnt go down much in storage and during grinding a
considerable amount of heat is generated. It is not desirable to allow the
temperature of cement above 120oC and preferably it should be below 100oC.
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CEMENT SI LO
After grinding the formed cement is transported to cement silos through air slides
for storage. There are 2 cement silos in the plant having 3 compartments each.
Design: 3 compartment siloCapacity: 15000 MT each silo
In KCP there are two cement silos.
Each silo have capacity of 15000 tones.
Total capacity of cement storage is 30000 tones.
Each silo has 3 compartments.
Silo 1 : 2 compartments of PPC
1 compartment of OPC 43
Silo 2 : 1 compartment of PPC
1 compartment of OPC
1 compartment of OPC 53
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PACKING AND DI SPATCH
The cement is transported into packing plant where the packing and dispatch ofcement takes place. The cement packed into plastic bags with help of packingmachines. There are a total of 8 packing machines in the packing section.
It consists of:1. Storage of element in silo.
2. Silo extraction system.
3. Packing of cement in bags.
4. Truck loaders.
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Cement Loading Capacity: 12000 MT/ Day
Packers :Make: EEL
Model: Roto Packer 6 RS-E(Electronic Packers)Capacity: 90TPH @ 3800 Blaine
No of Packers: 8Other machines in the packing section are:
Trailer Loading MachineMake: BeumerModel: B-18Capacity: 90 TPH
No of Machines: 14
Truck Loading MachineMake: EEL
Model: TLM 1020 J/BCapacity: 90TPH
No of Machines: 2
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FLOW DIAGRAM OF CEMENT SI LO AND PACKING
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PROCESS OF CEMENT PACKING
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Bulk Transport
Clinker is also bulk transported. From silo clinker is sent to the bulk loading
section via bucket elevators and conveyor belts. There are 2 silos in the bulkloading section. Clinker from silo is directly dumped into the trucks.The details of the section are:Make: DCL Bulk Technologies.
Clinker Hopper Capacity: 700 MTClinker loading capacity: 7200 TPD
Other important points are Two loading points
Stationary weighbridges at loading points enabling simultaneous loading andweighing of trucks.
Equipped with dustless loading spouts so that no dust emission duringloading.
No reverse movement of trucks.
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PROJECT ONHEAT BALANCE
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INTRODUCTION OF HEAT BALANCEIn Kotputli cement works dry process kiln system is used. The feed materials are
preheated by the hot gases from rotary kiln. A secondary burner is included toimprove energy efficiency. The mixture of the preheated and precalcined materials
enters the kiln, which is a counter flow reactor. Fuels together with air enter from
the opposite end. The solid feed is heated to an extremely high temperature in the
burning zone such that raw materials react and form clinker. Clinker exits the kiln
at about 1400 degree Celsius and is cooled down to less than 150 degree Celsius by
flowing air. Part of the heated air from the cooler enters the kiln, another portion
flows to the pre-calciner, the rest is gone to preheater by two tertiary air Ducts.
Diagram showing flow in preheater, kiln and cooler
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REASON OF HEAT BALANCE
The main purpose of heat balance is to find the Specific Heat consumption
of kiln system through fuel which is used for burning.
Heat Balance calculation is basically a calculation where heat inputs andoutputs are measured, calculated and compared.
We can yield information about where heat losses occur in the system.
Helps to study the system and diagnose any problems in it.
With this information the plant personnel can decide if any action is required and
identify the points where attention might be needed.
NECESSARY HEAT BALANCE CONSIDERATIONS:
For achieving a good heat balance following considerations should be followed:
The best way to secure a reliable result in heat balance is by ensuring that
the kiln operation is reasonably constant during the period of measurement,
at least 2-3 days. The measurements should reflect average values over a
time span of 8 hours.
To make proper balance it is necessary that all the figures are measured /
calculated individually.
For a heat balance to be reliable it is necessary that the inputs and outputs
established balance within a reasonable degree of accuracy; normally within
2-4% relative. A better result cannot be expected due to limitations on
accuracy of all the individual measurements.
It is important to establish the clinker production with high degree of
accuracy, as it forms basis for many of the calculations. Often plant uses an
approximate value for the kiln feed to clinker factor for estimating clinker
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production. This is often not accurate enough for a heat balance calculation,
so, the clinker must be either weighed or chemical analysis can be done.
The most reliable method is by weighing the clinker production
during the heat balance performance. This can be done on a weighing
bridge. The period required for obtaining a reliable result will often be
approximately 24 hours. If a smaller time span is used, the small
disturbances taking place, such as kiln going cold or hot, or the clinker layer
increasing or decreasing in the grate cooler, will greatly affect the weighed
production and introduce large errors.
All measurements carried out in the course of heat balance should ideally be
performed simultaneously. As this is seldom practically possible, it is
advantageous to identify those heat losses that can be considered almost
constant during the time in which measurements are taken and average
values can be used for the heat balance.
Highly variable and closely connected values must be measured as
simultaneously as possible to get consistent results. Typically connected
values in this sense include surface heat loss from cooler, clinkertemperature, preheater exit gas temperature and exit gas composition.
The magnitude of the various heat losses that enters into the heat balance is very
different. For instance the surface heat loss from a cooler will be approximately 5-
6 kcal/kg clinker while heat losses with excess air from a cooler will be as high as
120 kcal/kg clinker. The higher the value, the more important it becomes to ensure
that the value is correct and that measurement is reliable. The error that can be
caused by estimating surface loss is relatively small compared to the unavoidablemeasuring errors when determining the excess air
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METHOD OF CALCULATION
The main method of calculation is to consider the kiln as a system and then
calculating the Heat entering and heat leaving from the system. Pyro Section
consists of preheater, cooler and rotary Kiln so there are various heat inputs,
losses and outputs are going on. For this, Kiln is considered as a system and
heat balance is done.
Second step is to choose the reference temperature for the calculation of
sensible heats.
Third step is to define input and output material flows. Input include raw
meal , the fuel and the air. Outputs are smoke gas. The dust with the gas,etc.
Some other sources include heat of reaction of raw meal, latent heat,
sensible heat, and convection and radiation losses from surfaces.
Now the final result is calculated in kcal/kg clinker.
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EQUIPMENT USED
Various equipments are used to do the heat balance in kiln .Because for finding
out heat Inputs and outputs the temperature, pressure, flow, specific heat, are some
of the things that Have to be known. Some equipments names are given below:
Pitot tube -It is used to find static and dynamic pressure of the flow. We can
find out the difference between the pressure of two points and the pressure at a
single Point. It is very important for measuring the mass flow rate of gases and
feed Mass flow rate is then used to find heat coming or liberated. For calculatinggas velocities S-type Pitot tube is used. Pressures are measured using a digital
pressure meter.
In the case of Pitot tube the value of c taken to be .83.
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ThermocoupleIt is used to measure the temperature that is very important
for measuring heat inputs and outputs. By the use of temperature and pressure we
can also find out the density which helps in finding flow rate.
Anemometer- It is used to find the velocity of air fans which are used in the
calculation of heat conveying into kiln through air. By this we can directly measure
velocity of fans. For measuring Cooler fan velocities a thermal anemometer isused.
TERMS USED:
Specific heat: It is the amount of heat per unit mass required to raise the
temperature by one degree Celsius. The relationship between heat andTemperature change is usually expressed in the form shown below where cis the specific heat.
Q = Where q is the heat added or removed
Unit = KJ/kg
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Latent heat -latent heat is the heat released or absorbed by a body or a
thermodynamic system during a process that occurs without a change in
temperature. For example phase transition such as melting of ice or the
boiling of water.
Q = mL
Where L is the latent heat for a particular substance
Unit = KJ
Sensible heatIt is heat exchanged by a body thermodynamic system that
has its sole effect a change of temperature. the sensible heat of a
thermodynamic process may be calculated as the product of the bodys mass
(m) with its specific heat capacity(c) and the change in temperature same as
specific heat.
Heat of reactionit is the amount of heat that must be added or removed
during a chemical reaction in order to keep all the substances present at the
same temperature. If the pressure in the vessel containing the reacting
system is kept at a constant value, the measured heat of reaction also
represents the change in the thermodynamic quantity called enthalpy.
Calorific Value (CV):The calorific value or heating value of a
substance, usually a fuel or food, is the amount of heat released during the
combustion of a specified amount of it. The calorific value is a
characteristic for each substance. It is measured in units of energy per unit
of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m.
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1.SURFACE LOSS:
There are two types of heat loss from surfaces, namely convection andradiation.
Total surface loss = convection loss+ radiation loss
CONVECTION LOSS:It is the measure for heat escaping due to
cooling effects of surrounding air temperature. It will increase with
increase in movement of wind (wind speed). Air acts as medium of
heat transfer. Heat transfer takes place from higher temperature areas
to lower temperature areas.
RADIATION LOSS:It is the heat escaping the surface through radiation. It
depends on the surface temperature and emissivity of the material
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TABLE SHOWING HEAT INPUTS AND OUTPUTS
Heat inputs Heat outpu ts
Heat with kiln feed Heat of reaction of raw materials
Heat by air from cooler Heat from exhaust from kiln
Heat of Combustion Heat loss by dust
Heat by primary air Radiation and convection losses
Heat from moisture in feed Cooler water spray evaporation
Cooler air Heat from clinker out
Cooler water spray Preheater and cooler exhaust air
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SOME BASIC FORMULAS
1. Specific Heat calculation:
2. Fan Formulae:
a.Flow at operating conditions:
Fop = Cross-section area (or) Suction area * Velocity of air (or) gas m3/hr
b.Normal density of gas = (%gas/100)*Mol.wt/22.4 kg/Nm3
Mol.wtMolecular weight
c. Operating density =Normal density*((9884+PS)/(273+Top))*(273/10333)
kg/m3
9884 mmwg is the barometric pressure at sea level
PSStatic Pressure, mmwg
TopOperating Temperature,oC
d. Velocity of gas = m/sCPitot-tube constant, [here C = 0.83]
PDynamic pressure, mmwg
gacceleration due to gravity, m/s2
Operating Density, kg/m3
e. Mass flow:
Mf= kg/hrFopFlow at operating conditions, m
3/hr
Operating Density, kg/m3
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3. Sensible Heat:
Q = kcal/kg clinkerm: Specific mass, kg/kg of clinker
Cp: Specific heat capacity, kcal/kg-oC
Tbody: Temperature of the body,oC
Treference: Reference Temperature,oC
HEAT INPUTS:
There are various heat inputs in the kiln. They are calculated per kg clinker. These
are explained below:
heat by raw material
Q = mcHere m is the mass of the feed per kg clinker
C is the specific heat
And delta T is the difference in temperature
heat by primary air
Primary air consists of three types of air
Jet airto provide length to the flame
Swirl airto provide width to the flame
Cooling airto cool the burner
Heat by air from cooler: This air is also known as secondary air. It is
transported from Cooler to preheater through kiln and considered as a heat input.
This can be considered as a way to minimize waste air and calculated with formula
mc
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Heat of combustion:Heat of combustion of coal should also be taken into
account for Heat input. Because in Kotputli cement plant we are using two types of
fuels
Imported coal : Ii is mainly imported from south Africa. The composition
of this coal is taken to be 38% in the coal feed in Kotputli cement plant.Its
Calorific value is 6100 kcal/kg
Pet coke : It consists of fly ash also. The composition of pet coke in kcw
is taken to be 62%. Its calorific value is 7900 kcal/kg
Note : Pet coke percentage is higher than imported coal because: Pet cokes calorific value is very higher than imported coal
It is very cheaper than imported coal because it also consists fly
ash and generated here.
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HEAT OUTPUTS
Heat that is coming out of the kiln can be divided into following parts:
Heat of reaction: Heat of reaction can be calculated by the formula
4.11(Al2O3) + 6.48(MgO) + 7.646(CaO)5.1165 (SiO2) - .59(Fe2O3)
Where when we put the percentages of these compounds present in clinker we getthe heat of reaction.
Radiation Loss:The temperature of inside of kiln is very high. To prevent
radiation losses Refractory bricks are put inside the shell but then also kiln shell
temperature is very high. Due to the difference in temperature between kiln shell
and surrounding due to radiation heat Loss takes place. In preheater, tertiary air
ducts and cooler also loss is to taken into account. All cyclones have differenttemperatures so that also have to take into account
Radiation Loss = /(1000 * m)Here is the Boltzmanns constant (5.67 * 10^-8)
Is the emissivityA is the area
M is the mass of clinker in kg/hr
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Heat taken away by clinker: clinker that goes to the cooler from the kiln takes
is also at a high temperature of around 1250 degree Celsius. For calculating heat
due to it mass is taken to be 1kg/kg clinker and specific heat is calculated.
Heat taken by dust:The dust particle that moves from kiln to the preheater
also takes away some heat with them that is also taken into account. For
calculation purpose it can be considered as a constant.
Heat of moisture in input: Feed that is coming to the kiln also brings some
moisture with it this moisture has to be evaporated in order to complete dry
process. This can be calculated by the formula
Q = mL + mc
Heat of moisture in coal:The coal that is used for burning zone also bringssome moisture with it and to evaporate it is necessary. We have to consider both
pet coke and imported coal in it as their percentage in coal feed is different same
formula as stated above is used for calculating.
Heat of convection: convection losses are also there present in the kiln which
can be Calculated in kcal/kg clinker by the below represented formula
80.33 *
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Where 80.33 is constant
A is the surface area of the kiln
T inside is the temperature inside of pyro section
T surrounding is the temperature of the atmosphere
Clinker production in kg/hr
SOME MEASUREMENTS
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Specific heat data
String-1 PH fan % Density A B C Temp(oC) Sp. heat
CO2 30.0 0.59 0.196 118 -43 258 0.07
H2O 4.00 0.03 0.443 39 28 258 0.018
N2 59 0.74 0.244 22 0 258 0.148
O2 6.8 0.10 0.218 30 0 258 0.015CO 0.00 0.00
Total 100.0 1.46 0.248
String-2 PH fan % Density A B C Temp(oC) Sp. heat
CO2 30.0 0.59 0.196 118 -43 266 0.07
H2O 4.00 0.03 0.443 39 28 266 0.018
N2 60 0.75 0.244 22 0 266 0.150
O2 5.9 0.08 0.218 30 0 266 0.013
CO 0.00 0.01
Total 100.0 1.46 0.249
Air (cooler) ESP
exhaust 1.29 0.237 23 0 272 0.243Kiln feed 0.206 101 -37 78.4 0.214
Clinker 0.186 54 0 108 0.192
Fine Coal 0.262 390 0 67 0.288Kiln feed return dust 0.206 101 -37 262 0.230
Air (Cooler fan) 0.237 23 0 19 0.237
Air (PA blower) 0.237 23 0 65 0.238Air (PA fan) 0.237 23 0 20 0.237
Air (coal feed) 0.237 23 0 55 0.238
Air secondary 0.237 23 0 1120 0.263Air tertiary-1 0.237 23 0 865 0.257Air tertiary-2 0.237 23 0 896 0.258
Hot clinker 0.186 54 0 1400 0.262
Cooler water spray 0.443 39 28 19 0.444Kiln feed moisture 0.443 39 28 262 0.455
Density of flue gas 1.46
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1. TEMPERATURES AT VARIOUS POINTS:
PointoC
Air (cooler) ESP O/L 272Raw meal Kiln Feed 78.4
Clinker cooler discharge 200
Fine Coal 67
Raw meal return dust 250
Air (Cooler fan) 19
Air (Primary Air blower) 65
Air (PA fan) 20
Air (coal feed) 55
Air secondary 1120
Air tertiary 900
Hot clinker 1400
2. CLINKER COMPOSITION:
Composition of clinker should be taken on the same day of doing heat
balance. Clinker composition can be acquired from the Quality Control
department of the plant.
Oxide Symbol %
SiO2 (S) 20.95
Al2O3 (A) 5.22
Fe2O3 (F) 4.35
CaO (C) 62.21
MgO (M) 4.85
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3.BLOWERS AND FANS:
Blower/Fan Temperature(oC)
Static Pressure(mmwg)
Burner cooling fan 20 622
Jet air blower 65 7003
Swirl air blower 20 179
Pyroclon1 blower 44 2131
Pyroclone2 blower 45 2516
LowNOx blower-1 54 3910
Kiln Coal conveying
blower44 2271
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C.S.
length Area
T1
(0C)
T1
(0K)
0-1 18 300 573
1-2 18 285 558
2-3 18 280 553
3-4 18 275 548
4-5 18 270 543
5-6 18 240 513
6-7 18 120 393
7-8 18 150 423
8-9 18 220 493
9-10 18 200 473
10-11 18 220 493
11-12 18 220 493
12-13 18 200 473
13-14 18 210 483
14-15 18 260 533
15-16 18 300 573
16-17 18 300 573
17-18 18 300 573
18-19 18 300 573
19-20 18 300 573
20-21 18 150 423
21-22 18 150 423
22-23 18 150 423
23-24 18 145 418
24-25 18 150 423
25-26 18 300 573
26-27 18 325 598
27-28 18 340 613
28-29 18 330 603
29-30 18 310 583
30-31 18 310 583
31-32 18 300 573
32-33 18 250 523
33-34 18 200 473
34-35 18 300 573
35-36 18 280 553
36-37 18 300 573
37-38 18 295 568
38-39 18 300 573
39-40 18 310 583
40-41 18 315 588
41-42 18 310 583
C.S.
length Area
T1
(0C)
T1
(0K)
42-43 18 310 583
43-44 18 300 573
44-45 18 260 533
45-46 18 250 523
46-47 18 255 528
47-48 18 260 533
48-49 18 255 528
49-50 18 255 528
50-51 18 260 533
51-52 18 260 533
52-53 18 265 538
53-54 18 260 533
54-55 18 270 543
55-56 18 260 533
56-57 18 260 53357-58 18 265 538
58-59 18 260 533
59-60 18 255 528
60-61 18 200 473
61-62 18 130 403
62-63 18 240 513
63-64 18 230 503
64-65 18 225 498
65-66 18 200 473
66-67 18 150 423
67-68 18 135 408
68-69 18 200 473
69-70 18 205 478
70-71 18 210 483
71-72 18 225 498
72-73 18 235 508
73-74 18 235 508
74-75 18 230 503
75-76 18 230 503
76-77 18 230 503
77-78 18 225 498
78-79 18 225 498
79-80 18 220 493
80-81 18 210 483
81-82 18 200 473
82-83 18 145 418
83-84 18 110 383
84-85 18 100 373
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Above table indicates the temperatures of kiln shell at surrounding temperature
313 degree kelvin.
CALCULATIONS
HEAT OUTPUTS
Heat of reaction
Material percentage
Al2O3 5.22
Fe2O3 4.35
CaO 62.21
MgO 4.85
SiO2 20.95
Q = 4.11 x A + 6.48 xM + 7.646xC - 5.1165xS - 0.59x F
= 418.783 kcal/kg
Heat in clinker out
Q = mc ()(1 kg/kg clinker) * 0.192 kcal/kg* (2000)
= 38.4 kcal / kg clinker
Heat of moisture in input
Moisture % in feed = 0.16
Total input feed = 648 Tph
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Total moisture in input = (0.16 / 100) *648 *1000 =1040 kg/hr
So, in 1 kg clinker moisture is = (1040 /405000) = 0.0025 kg/hr
Heat of moisture = mL + mc= 0.0025 * 597 + 0.0025 * 0.5 *(2500)
= 1.805 kcal/kg of clinker
Moisture with coal
Pet coke percentage = 62 %
Imported coke percentage = 38 %
Let total coal consumption = X
Pet coke moisture = .7 %
Moisture in imported coal = 1.98 %
Total moisture in coal is = (.62 * .007 * X) + (.38 * .0198 * X)= .01184X kg/kg clinker
So, heat of evaporation in coal moisture= (.01184X)*597 + (.01184X)*(.5)*(67-0)
= 7.29 X
Heat loss by dust
Percentage of dust in feed = 4 %
So, dust present in feed = 4 % of 648 Tph = 26 Tph
So, per kg of clinker = (26 / 405) = 0.064 kg/kg clinker
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Q = mc= 0.064 * 0.23 * (262-0) = 3.85 kcal/kg
Heat loss by radiation
1. by kiln shell:
Q = / (1000 * m)= {4.87 * 10 ^ (-8) * 3.14 *85 *5.8*(513^4313 ^4)} / (1000*405)
= 11.11 kcal/kg clinker
Heat loss by convection
= 80.33 *
= [80.33 *(3.14*85*5.8) *{(513+313)/2} ^ (-.724) * (513-313) ^
1.33]/(1000*405)
= 4.576kcal/clink
Note: Radiation and convection losses from preheater, tad and cooler is
taken to be 35 kcal/kg clinker
Heat in preheater exit gasesTotal Kiln feed 648 TPHClinker output 405 TPHClinker output 405000 kg/hr
a) String-1 Preheater
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Fan
Total Gas flow 641645.0 m3/hr
Total Gas flow 420756.5 kg/hrSpecific mass (m) 1.039 kg/ kg clinkerCp 0.248 Kcal / Kg
oC
Gas temp. 258.0
o
C
Qa= 66.6
Kcal/Kg of
clinker
a) String-2 PreheaterFanTotal Gas flowDensity
664563.91.54
m3/hr
kg/ m3
Total Gas flow 428823.3 kg/hr
Specific mass (m) 1.059 kg/ kg clinker
Cp 0.249 Kcal / KgoCGas temp. 266.0
oC
Qb= 70.1
Kcal/Kg of
clinker
(Qa+ Qb = Q= 136.7
Kcal/Kg of
clinker
Heat in cooler exhaust air
Kiln feed 648 TPHClinker output 405.00 TPH
405000 kg/hrGas flowDensity
827386.61.62
m3/hr1.62kg/ m3
Mass flow rate 509652.5 kg/hrSpecific mass (m) 1.3 kg/kg of clinkerCp 0.243 Kcal / Kg
oC
Q= 83.3
Kcal/Kg of
clinker
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Heat of cooler water spray evaporation
Kiln feed 648 TPHClinker output 405.0 TPH
405000.0 kg/hrWater spray in cooler 5.6 KL
5600 Kg
sp. Masstempspecific heat
0.013190.444
kg/kg of clinker
Kcal/kg
Heat loss for coolerwater spray 10.2
Kcal/Kg of
clinker
Heat inputs Heat with kiln feed = mc()
= (648/405) * 0.260 *(90-0)
=37.55 kcal/kg clinker
Heat of combustion
Q = calorific value * mass of fuel
= CV * X
Mass of pet coke = .62X
Mass of imported coal = .38X
Calorific value of pet coke = 7900 kcal/kg
Calorific value of imported coal = 6100 kcal/kg
Q = 7900*.62X + 6100 * .38X
= 7216X
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Heat by primary air
i) Jet airTemp. 65
oC
Air density 1.7027 kg/m3
Air flow 5724.2 m3/hr.9747.11 kg/hr.
air specific mass(m) 0.024 kg/kg clinkerCp 0.24 Kcal / Kg
oC
Q1= 0.37Kcal/Kg of
clinker
ii) Swirl air
swirl air dia 250 MmArea 0.05 m
2
Air velocity 6.04 m/secTemp. 20
oC
Air density 1.17 kg/m3
air flow 0.30 m3/sec
1066.9 m3/hr
1248.9 kg/hrair specific mass(m) 0.003 kg/kg clinkerCp 0.237 Kcal / Kg
oC
Q2= 0.01Kcal/Kg of
clinker
iii) Burner coolingairTemp. 20
oC
Air density 1.22 kg/m3
air flow 1861.8 m3/hr.
2275.2 kg/hr.
air specific mass(m) 0.006 kg/kg clinkerCp 0.237 Kcal / Kg
oC
Q3= 0.03Kcal/Kg of
clinker
iv) Kiln Coal
conveying air
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Temp. 44.00oC
Air density 1.31 kg/m3
Air flow 6084.2 m3/hr
7948.7 kg/hrair specific mass(m) 0.0196 kg/kg clinkerCp 0.2385 Kcal / KgoC
Q4= 0.21Kcal/Kg of
clinker
v) PC Coal conveying air -1Temp. 44
oC
Air density 1.29 kg/m3
Air flow 6105.7 m3/hr
7887.2 kg/hr
air specific mass(m) 0.0195 kg/kg clinkerCp 0.238 Kcal / Kg
oC
Q5= 0.20Kcal/Kg of
clinker
vi) PC Coalconveying air -2Temp. 45.00
oC
Air density 1.33 kg/m3
Air flow 6059.3 m3/hr8052.7 kg/hr
air specific mass(m) 0.020 kg/kg clinker
Cp 0.238 Kcal / KgoC
Q6= 0.21Kcal/Kg of
clinker
vii) LOW NOX CoalConveying air-1
Temp. 54o
CAir density 1.44 kg/m
3
Air flow 6705.9 m3/hr
9641.1 kg/hrair specific mass(m) 0.024 kg/kg clinkerCp
Kcal KgoC
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Q7= 0.31Kcal/Kg of
clinker
Total Q =Q1 + Q2+Q3+Q4+Q5+Q6+Q7
Q = 1.34Kcal/Kg of
clinker
Heat in clinker cooling air
Temp = 19 degree Celsius
Specific mass = 2.39 kg/kg of clinker
Cp = .237 kcal/kg
Q = 10.8 kcal/kg of clinker
Cooler water spray
Kiln feed 648 TPHClinker output 405.0 TPH
405000.0 kg/hrWater spray in cooler 5.6 KL
5600 Kgsp. Mass 0.013 kg/kg of clinkerSpray water
temperature 19oC
Heat by cooler waterspray 0.109
Kcal/Kg of
clinker
Sensible heat of fuel
specific mass (m) X kg/ kg clinkerT 67
oC
Cp 0.2881 Kcal / KgoC
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Q = 19.3 X Kcal/Kgclinker
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Total heat Input
7216 X37.5510.8
1.340.10919.3 X
7235.3 X + 49.799
Total heat output
418.7833.85136.7
38.483.31.8057.29 X10.250.686
743.724 + 7.29 X
Total heat Input =
Total heat
output
7235.3X + 49.799 =743.724 + 7.29X
7228.01 X = 693.925
X = 0.096kg coal /kgclinker
Coal consumption 0.096
kg coal /kg
clinker
Heat consumption 692.7 kcal/kg clinker
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SUMMARY OF HEAT BALANCE
Kiln Feed = 648 Tph
Clinker out = 405 Tph
Kcal/kg
clk. %
Kcal/kg
clk. %
Clinker 38.4 5.2 Cooler air 10.8 1.4
Heat of reaction 418.8 56.3 Kiln feed sensible heat 37.6 5.1
Kiln feed return dust 3.9 0.5 Fine coal sensible heat 1.9 0.2
Moisture evaporation 2.5 0.3 Coal conveying air 0.9 0.1
Cooler exhaust air 83.3 11.2 Primary air sensible heat 0.4 0.1
Preheater flue exhaust gas 136.7 18.4 Cooler water spray 0.1 0.0Cooler water spray
evaporation 10.2 1.4 Coal specific heat 692.7 93.1
Kiln 15.7 2.1
preheater ,tad and cooler 35.0 4.7
Total 744.4 100 Total 744.4 100
* All heat measured in kcal/kg clinker
Net specific heat
consumption(coal)692.7
Kcal/Kg
clinker
Radiation & Convection losses
Heat output Heat input
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OPTIM ISATION IN CEMENT KILN
ROTARY KILN FIRING SYSTEMS
The minimizing excess air in rotary kiln without any formed CO leads toimprovement in the performance of the kiln and consequently leads to reduce the
fuel energy consumption shorten and intensify the flame leads to reduce the fuel
energy consumption. Further in Plant optimized kiln burner primary is also
considered for decreasing fuel energy consumption
Lime saturation factor, sillica moduli and alumina moduli of kiln feed
The fuel consumption can be decreased by reducing lime saturation factor (LSF),
sillica Moduli (SM) and alumina moduli (AM) of kiln feed. These ratios are very
important for producing the optimum quality of cement required.
Fuel quality and fuel combustion efficiency
In Kotputli cement plant largest proportion of energy consumed in manufacturing
of cement consists of fuel that is used to heat the kiln. Therefore, the greatest gain
in reducing input may come from improved fuel efficiency. The fuel energy
consumption can be decreased by selecting the type of fuel which having higher
calorific value and easy to combustion. In Addition to that, by adjusting the flame
shape, the fuel energy consumption in the plant can be improved.
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UTIL I ZATION OF WASTE HEAT
The overall efficiency of the kiln system can be improved by recovering some of
the heat Loss. The recovered heat energy can then be used for several purposes
such as for electricity Generation. Some major heat losses that can be considered
for heat recovery are heat losses by kiln exhaust gas, hot air from cooler stack and
radiation from the kiln surface. The amount of the heat in the waste gases can be
utilized mainly depends upon the flows, Temperature of the waste gas and thermal
capacity of the waste gas. Some methods can be done as below:
Exhaust gas from preheater
In the preheater mainly moisture removal takes place and heat is utilized in thatway but the Temperature of the gases is very high. If the raw materials moisture
content is low, we can only use a part of this gas for drying. In this case a waste
heat boiler can be installed which Utilizes the upper temperature of the exit gas at
around 300 degree Celsius.
Exhaust air from the cooler
In a cooler considerable amount of exhaust air is obtained as waste air. Thetemperature of this waste air lies in the range 200-300 degree Celsius. The exhaust
air can be extracted from the cooler at two different points. In this case, waste air
can be divided into zones inside the cooler, colder and hotter portions. The hottest
portion can be used for heating of the thermal and drying of slag. It can also be
used for steam. A colder portion of air could be used for heating of water to
produce steam to generate power by using turbine.
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