4.project report
TRANSCRIPT
CHAPTER 1
INTRODUCTION
1.1 ORGANIZATION Fertilizers And Chemicals Travancore Limited is the largest public sector
undertaking in Kerala. The Fertilizers And Chemicals Travancore
Limited ,popularly known as FACT which setup the first large scale Nitrogenous
factory in the country ,as early as 1944, on the back of Periyar at
Udyogamandal, near the Cochin Port . From a single product fertilizer plant of
the forties ,FACT has through the years grown into a large multi-product ,multi-
divisional corporation today a legend of our times and triumph of the public
sector .FACT’S two fertilizer manufacturing divisions at Udyogamandal and
Cochin together have so far produced and distributed millions of tones of
fertilizer nutrients .which has helped farmers to produce over 50 millions tones
of food grains .FACT’S Marketing division has a well organized sales network,
which ensures that even the farmer un the remotest village is fully benefited
through its agronomy and rural developments services .The rich fund of
expertise, experience and skills gained over the years in manufacturing units of
FACT were pooled together in the mind sixties to form two separate engineering
divisions ,FACT Engineering & Design Organization(FEDO) & FACT
Engineering Works (FEW). These two Divisions between them cover the entire
spectrum of Consultancy and Engineering Services and have contributed a great
deal to attain self- reliance in fertilizer and chemical technology in the
country .In 1990 ,FACT further diversified into the field of petrochemicals by
setting up a Carprolactum unit .Today ,FACT is on the threshold of further
diversification and backward integration .
FACT COCHIN DIVISION is the second manufacturing Division of
FACT The factory is situated at Ambalamedu adjacent to BPCL Kochi
Refinery .The division was formed as a part of the planned efforts by
Government to give the greatest scope to the use of indigenous technology in
setting up large sized fertilizer plants. FEDO and P&D of PDIL were entrusted
with responsibility of installing these large plants with artificial reservoir over
200 acres to meet the water requirements of plants and townships.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
The Phase 1 of the Division, with facilities to produce 1, 98,000 tonnes of
Ammonia and 33,000 tonnes of Urea per annum went into commercial
production in 1973.Licence for the Phase 2 conceived to manufacture complex
fertilizer was issued in1972 .The Phase 2 plants were commissioned in the year
1976 .But due to financial crisis, Phase 1 plant is not produce presently. Only
Phase 2 plants are to production now. Phase 2 consists of three plants
namely ,Sulphuric acid Plants ,Phosphoric acid Plants and NP Plants having
annul capacities of 3,33,000MT, 115200MT of P2O5 and 4,85,000 MT of
complex fertilizer respectively. The Factory site is connected by road, rail and
waterways which facilitate the movement of raw materials and products.
Consistent with commitment to environmental health ,all necessary safeguards
have been built in to take of water and atmospheric pollution caused by effluent
gases and liquids thrown out from the factory .FACT COCHIN DIVISION has a
track record of earnestness in combating pollution .The effluent are treated with
controlled lime addition, an amorphous recovery plant ,fumes scrubbers for
emissions from Complex fertilizer Plant, DCDA Process with Candle Filters at
the intermediate absorption tower of Sulphuric acid Plant and Alkaline scrubbing
of emissions form Phosphoric acid Plant.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
1.2 NEED FOR THE PROJECT
Operations and Plant Maintenance are crucial aspects and the overall
profitability of any Company depends to a great extend on them. Maintenance plays a
key role in keeping the plant available for effective operation through out the
year .The maintenance practices followed by any Company can be improved by
analyzing previous maintenance logs and equipment histories to find frequent troubles
and finding solution to overcome those troubles by analyzing its root cause and
adopting correct maintenance technique and by scheduling the maintenance program.
It is said that “An ounce of prevention and predictive maintenance is worth a pound of
cure”. Plant efficiency can be improved by analyzing method to decrease break down
through adopting different techniques which does not increase the operational cost.
A true maintenance optimization process continually monitors and optimizes the
current maintenance, program to improve its overall efficiency and effectiveness. The
effort to initiate the maintenance optimization process can be eliminated over time if
additional effort is not taken to sustain the process.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
1.3 OBJECTIVE
Maintenance Optimization is a process that attempts to balance the maintenance
requirements (legislative, economic, technical, etc...) and the resources used to carry
out the maintenance program (people, spares, consumables, equipment, facilities,
etc…). The goal of the maintenance optimization process is to select the appropriate
maintenance technique for each piece of equipment within a system and identifying
the periodicity that the maintenance technique should be conducted to achieve
regulatory requirements , maintenance targets concerning safety, effectively
implemented it will :
improve system availability
reduce overall maintenance costs
improve equipment reliability
improve system safety
The maintenance optimization process will effectively blend predictive,
preventive, productive, and corrective maintenance strategies. This will allow the
system’s maintenance program to move from a reactive approach or a preventive
approach to a planned approach .The planned approach conducts maintenance at the
most optimum time, which is often before the equipment fails, whereas the reactive
approach performs maintenance strictly on a scheduled basis.
The objective of this project is the Optimization of Mechanical Maintenance of
Phosphoric Acid Plant.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 2
MAINTENANCE
Maintenance is a set of organized activities that are required to carry out in order
to keep an item in its best operational condition with minimum cost acquired.
2.1 PREDICTIVE MAINTENANCE:
It is a method of predicting the failure before it occurs, identifying the root
causes for those failure symptoms and eliminating those causes before they results in
extensive damage of equipment.
This can be classified into two methods:
Condition based predictive maintenance(CBM)
Statistical based predictive maintenance.
There is a lot more useful information in the data collected than just the lubricant
quality, trends, and tailing components. Aside from the reliability aspect that
predictive maintenance can provide, there are significant cost savings potentials
available through effective smart maintenance. Doing the right thing, at the right time,
for the right reason.
Condition Based Maintenance (CBM):
Most electric motors have small volume lubricant reservoirs and thus, oil analysis
is generally done for equipment condition rather than lubricant quality. Oiled motors
where originally set up with a one year frequency PM for oil changes. Even with good
lubricant handling practices there were still significant swings in the ISO code
cleanliness. The high spike was generally right after an oil change with the cleanest
being right before an oil change.
The dirt in circulation of a hydraulic system will cause damage. A motor may not
have the same flow as a hydraulic, but the slinger rings do a great job of circulating
wear debris within the bearing reservoir. This of course causes wear to the shaft
journal and the slingering showing up as iron, chromium or brass in the oil analysis.
Unfortunately most motors do not have circulation systems or filtration to remove
wear debris once they are there, they must slowly be settled out to be stirred up again
during an oil change.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
Root Cause Analysis (RCA):
Root cause analysis is an important part of a functional predictive maintenance
program.Another ease for RCA revealing an oil related problem occurred in some of
our motors with submerged coolers and hydraulic unit heat exchangers that were
made of Copper.
Another great example of a few minor changes to upgrade the equipment came
when the effluent processing facility was modified to produce synthetic gypsum from
our scrubber slurry. This change in operating process placed some of the equipment in
different operating parameters which of course caused problems. The plant
modifications were well worth it since it reduced our landfill use by up to 75%. One
gear reducer was failing every 3 to 5 weeks from the ingress of fly ash which looked
like lapping compound and was wearing the gears and bearings to failure. With some
basic improvements such as an increase in lubricant viscosity, bearing isolators,
kidney loop filtration, and breathers we have improved the time between failures to
better than 3.
There was a crack developed in ball mill in ring gears. It was first identified
through vibration data and monitored closely for almost a year until we were able to
schedule the gear replacement. This allowed normal expediting of parts and
workforce rather the added expense of doing it on an emergency basis. We are also
able to identify ball mill gear, reducer gear, and bearing problems early enough to
schedule and plan the replacement for a time of least economic impact. At times, the
failure might progress faster than expected but at least we have everything ready,
which removes the unknown factor from equation
2.2 PREVENTIVE MAINTENANCE:
It is a set of activities that are performed on plant equipment, machinery and
systems before the occurrence of a failure in order to protect them and to prevent or
eliminate any degradation in their operating conditions. This method relies on the
machine’s condition to accurately schedule the repairing interval e.g. cleaning,
inspection, oiling and re-tightening etc. Objective of this type of maintenance is to
retain the healthy condition of equipment and failure through the prevention of
deteriorization by periodic inspection or equipment condition diagnosis.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 3
OPTIMIZATION
The design and operation of systems or processes to make them as good as
possible in some defined sense. The approaches to optimizing systems are varied and
depend on the type of system involved, but the goal of all optimization procedures is
to obtain the best results possible (again, in some defined sense) subject to restrictions
or constraints that are imposed. While a system may be optimized by treating the
system itself, by adjusting various parameters of the process in an effort to obtain
better results, it generally is more economical to develop a model of the process and
to analyze performance changes that result from adjustments in the model. In many
applications, the process to be optimized can be formulated as a mathematical model;
with the advent of high-speed computers, very large and complex systems can be
modeled, and optimization can yield substantially improved benefits.
Optimization is applied in virtually all areas of human endeavor, including
engineering system design, optical system design, economics, power systems, water
and land use, transportation systems, scheduling systems, resource allocation,
personnel planning, portfolio selection, mining operations, blending of raw materials,
structural design, and control systems. Optimizers or decision makers use
optimization in the design of systems and processes, in the production of products,
and in the operation of systems.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 4
PHOSPHORIC ACID PLANT
The phosphoric acid plant is designed to produce 360 TDP of P2O5 through the
dihydrate route. The plant designed by FEDO in collaboration with Messer’s, Society
of Prayon of Belgium employs the Prayon covetable process to give a product having
strength of 30% P2O3. A separate concentration section is provided to concentrate this
weak acid having strength of 45% P2O5.
4.1 PROCESS
Rock phosphate of around 74 BPL is ground to the required size (90% through
100 Mesh Taylor Sieve) in a rock grinding section.
This ground rock is fed at a regulated rate through a gravimetric (Libra) weigh feeder
into a multi compartment Attack Tank where a large quantity of slurry is maintained
in circulation. At another point in the attack tank 98% acid is fed along with weak
recycle phosphoric acid. The rock phosphate react with Sulphuric acid and the
following reactions results.
Ca3(PO4)2 + 3H2SO4 2H3PO4 + 3CaSO4
Ca3(PO4)2 + 4H3PO4 3Ca(H2PO4)2
Ca(H2PO4)2 + 3H2SO4 3CaSO4 + 6H3PO4
A portion of slurry from the attack tank is continuously circulated through an
evaporator cooler called the flash cooler to remove the excess water from the system
as well as to prevent the attack tank slurry temperature from going up and causing
semi hydrate formation.
A portion of slurry over turn from the attack tank into a series of three digestive
vessels (to give sufficient time for crystal formation) and is then pumped to a rotating
tilting pan filter.
In the filter known as prayon filter, the slurry which consists of phosphoric acid
and gypsum (calcium sulphate dehydrate crystal) is filtered aided by vacuum. The
filtrate is a product acid which goes to the 30% acid settler. The filter cake which is
gypsum is deposited through a dry disposal system which has replaced the original
system.
In the filter after the recovery of 30% acid as filtrate the cake is washed counter
currently first with water. The water yields 5% P2O5 acid and this is used again for
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
washing to yield12% acid and yet again to yield 18% acid which then goes to the
attack tank along with Sulphuric acid as weak recyclic acid.
The 30% P2O5 acid collected in the settler can be either stored as such in storage tank
or can be concentrated further in a concentration section laid out in two streams.
Forced circulation evaporators having Karate tube heat exchangers and operating
under and a vacuum can concentrate all weak acid to 45% P2O5 or even 54% if a
reduction in output is allowed.
The fluorine content of the rock is liberated partly in the attack section during
reaction with sulphuric acid. The major portion of fluorine going along with the
products get liberated in the evaporator and is recovered by fluorine scrubber system
as Fluosilic acid having 13% H2SiF6 the fluorine evolved in the attack tank is also
collected in a scrubber and joins the Fluosilic acid from the concentration section.
Fig:1 Phosphoric Acid Plant
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 5
CORROSION OF METALS
The main mechanical problem in PAP is the cohesiveness of metals. The 20%
of the total cost issued for materials, so it is very important to reduce corrosion by
using corrosion preventive materials.
In PAP we use HV9/904L and MSRL material. The cost of HV9 is
comparatively higher than MSRL. So we use HV9 for machines/ equipments and
MSRL for pipes. The failure rate of MSRL is found to be very high. The main reasons
for failure are given below.
1. Bulging of lining
2. Failure of lining due to poor workmanship.
3. Damage to the lining caused during cleaning of pipes to remove deposits.
In this project we have 50 no’s of used tubes in primary reformer of ammonia
plant(now ammonia plant is not working and it is scrap).The reformer tube is of
material HK40 and HP50(casting).The material of composition of HK40 and HP50
are compared with HV9 material and found to have only minor changes in their
chemical composition.
If we use HK40 and HK50 in place of MSRL we can reduce the cost of MS and
rubber lining and it is a good corrosion resistant material also.
TABLE 1 : COMPOSITIONS OF HK40, HP50 AND HV9
Alloy/elements C Cr Cu Mn Mo Ni P S Si V
HV9 0.02 19 1 2 4.5 24 0.04 0.035 1 0.5
HK40 0.35 25 0.4 20 0.03 0.03 0.5
HP50 0.5 26 0.73 32 0.04 0.04 1.21
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TABLE 2 CORROSION RATE (MM/YEAR)
PHOSPHORIC ACID
Conc %
weight
CONDITION HP50 HK40 HV9
50 Boiling 0.03 0.01 0.18
60 Boiling 0.08 0.14 0.28
70 Boiling 0.15 0.35 0.13
80 Boiling 0.40 0.61 0.31
PHYSICAL PROPERTIES 0F HK 40
Density (lbs/in3)= 0.280
Melting Point(oF) =2540 @ 1760oF
Thermal Conductivity =7.9 @ 212oF
Thermal Expansion= 9.8 @ 70-1400oF
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CHAPTER 6
BUCKET ELEVATOR
A bucket elevator, also called a grain leg, is a mechanism for hauling flowable
bulk materials (most often grain or fertilizer) vertically.
Fig: 2 Bucket Elevator
It consists of:
1. Buckets to contain the material;
2. A belt to carry the buckets and transmit the pull;
3. Means to drive the belt;
4. Accessories for loading the buckets or picking up the material, for receiving
the discharged material, for maintaining the belt tension and for enclosing and
protecting the elevator.
A bucket elevator can elevate a variety of bulk materials from light to heavy
and from fine to large lumps. A centrifugal discharge elevator may be vertical or
inclined. Vertical elevators depend entirely on the action of centrifugal force to get the
material into the discharge chute and must be run at speeds relatively high. Inclined
elevators with buckets spaced apart or set close together may have the discharge chute
set partly under the head pulley. Since they don't depend entirely on the centrifugal
force to put the material into the chute, the speed may be relatively lower.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
Nearly all centrifugal discharge elevators have spaced buckets with rounded
bottoms. They pick up their load from a boot, a pit, or a pile of material at the foot
pulley.
The buckets can be also triangular in cross section and set close to on the belt
with little or no clearance between them. This is a continuous bucket elevator. Its
main use is to carry difficult materials at slow speed.
6.1 PROBLEMS IN BUCKET ELEVATOR
The problem it was facing was the frequent breakage of the drive chains. The
reason was that, the non return valve of the elevator was broken, as soon as the
machines were shut down the semi-loaded elevator returns due to the huge weight
inside it and falls freely. This motion directly affects the chain linked to the gear box
and serious cases of damages to the chain and the sprocket were recorded.
6.2 SUGGESTION:
These set of damages can be overcome by two methods:
A new back-stopper can be employed , which will, for sure prevent any backward
motion of the bucket-elevator.
Another method is to run the elevator for one round without loading, just before
shutting the plant. By doing this the weight on either side of the elevator is balanced
and there will not be any backward motion.
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CHAPTER 7
ATTACK TANK AGITATOR
Report On Attack Tank Agitators Drive Gear Box In Phosphoric Acid Plant
The phosphoric acid plant was commissioned with Hansen transmission gear
boxes for 11th 12th 13th 14 15 compartment agitators. Out of these 11 12 are identical.
In the long run of the equipments several failures occurred. As part of indigenization
of gear box, 3 gear boxes were produced from Greaves and in use now. The details of
the gear boxes presently installed running are given below:
11th compartment
Make : Hansen Patent
Model : 724 LITS
RPM : 870/78.5
HP : 150
Motor rpm : 1000 AM 15 mss
Pully dia. : 355/400
Agitator speed : 78.5
12th compartment
Make : Hansen Patent
Model : 724 LITS
RPM : 870/78.5
HP : 150
Motor rpm : 1000 Ah 315 mss
Pully dia: : 355/400
Agitator speed : 78.5
13th compartment:
Make : Greaves gears
Order no : 324569
Type : vb2 315sa
Ration : 12.6/1
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14th compartmentName plate is not available
Make : Hansen Patent
15th compartment:
Make : Greaves gears
Order no : 75213
Type : vb2 315sa
Ration : 12.6/1
16th compartment:
Make : Greaves
Type : vb2 250 sa
Ration : 17.1/1
Fig 3: Attack Tank Agitator
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7.1 DETAILS OF REAPIRS DONE IN ATTACK TANK AGITATORS (in the year 2011)
TABLE 3: 12th Compartment:
Date COMPLAINTS REPAIR DONE21/1/11 Agitator broken Agitator replaced
TABLE 4: 14th Compartment:
Date COMPLAINTS REPAIR DONE26/2/11 Agitator broken Agitator replaced10/10/11 Agitator broken Agitator replaced
TABLE 5: 15th Compartment:
Date COMPLAINT DEFECTS
REPAIR DONE
26/2/11 Agitator broken Agitator replaced
7/6/11 Agitator broken Agitator replaced
10/10/11 Agitator broken Agitator replaced
Agitators in compartments 11,13,16,21 had no repairs done in this time period.
CONCLUSION
There is all kind of spares of attack tank agitator gear boxes kept in the store.
The gear boxes of 11 and 12 compartments are identical. By replacing other gear
boxes with the gear boxes of compartment 11 and 12 it can be reduced the number of
spares kept in the maintenance store. So the cost can be thus reduced.
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CHAPTER 8
PRAYON FILTER
Fig: 4 Prayon Filter
One of the key equipment in phosphoric acid plant is Prayon filter. Any failure
in this will cause the extraction of acid into a halt. When analyzed it is found that the
bearing of filter tray is frequently failing. The device for supporting the rotating shaft
is called bearing. There are 20 x 1(outer roller), 18 x 1 (inner roller) and 14 x
1(supporting roller) which are used in this filter. The roller bearings are frequently
failing because of the corrosive action of phosphoric acid and also the corrosion
because of gypsum. From the inspections carried out it is found that the admission of
acid and gypsum can be prevented if the bearings are properly lubricated with grease
which acts as a seal. Any repair of the tray will consume at least 2 hours and require 6
labors .Hence by ensuring proper lubrication down time can be reduced as it is one of
the major equipment there by increasing the operational efficiency.
8.1 IMPROVEMENTS
A special compact vacuum box for separating gases and the various filtrates
A fast-drain filtration cell which can increase filter capacity and filtration yield
An automatic system to keep the pans horizontal
A new tilting-track design for higher rotation speed and filtration capacity
Support rollers designed for heavy loads
A robust car frame with a replaceable wear plates
TDI filter
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
Fig: 5 TDI filter
8.2 MAIN BENEFITS
Prayon filters are highly reliable due to their robust design. A number of filters
sold in the 1960s are still in operation;
On-stream factor of over 95%;
Excellent ratio between capacity and extraction yield, due to batch filtration
and a high level of authorized maximum vacuum;
Extremely energy-efficient equipment;
Negligible recycling of the solids recovered during cloth washing means that
the cake discharged from Prayon filters contains a minimal quantity of free
water;
High reliable experience with very large filters(e.g. 30-240 filter with a
surface area of 275 m²).
Main benefits of TDI filter
Compactness
Batch filtration
Fewer mechanical parts
Lower energy consumption
Lower investment costs
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CHAPTER 9
CONVEYOR DESIGN MODIFICATION
9.1 DESCRIPTION
Conveyors are rotating machines, which transmit raw materials, semi
finished, finished material. Normally conveyors are used for short distance
applications. Conveyors primarily perform the movement of uniform loads between
fixed points. They occupy space continuously except when they are of portable type.
They reduce handling. Different types of conveyors are belt, roller, screw, pipeline,
monorail, trolley etc. Conveyors are useful when
Loads are uniform
Materials move continuously
Routes do not vary
Movement rate is relatively fixed
Conveyors have three parts rotor, idler and belt. The rotor connects with the motor by
using coupling, chains. For longer belts a weight is added to the lower portion of belt
to maintain tension in belt.
9.2 CONVEYORS USED IN PAP
In PAP the materials are transmitted by using conveyors for solid/powder materials,
fluid materials are passed by pipelines. Different conveyors used in PAP are described
below.
Belt conveyors for transmitting rock phosphate from barge to grinding mill.
Bucket conveyors to transmit fine phosphate from grinding mill.
Screw conveyor
Gypsum belt conveyors transfer the byproduct gypsum into a temporary
storage place.
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TABLE 6 : REPAIRS DONE IN CONVEYOR G3 (in 2011):
Date COMPLAINTS REPAIR DONE ANALYSIS
19/2/11 Sprocket
damaged
gear box with
socket replaced
Oil seal leak
2/6/11 Belt worn Belt replaced Long run
9/7/11 Chain damaged 1” Triplex chain
replaced
Lack of lubrication,
6/12/11 Chain damaged 1” Triplex chain
replaced
gypsum deposits
inside chain guard
6.3 PROBLEMS FOUND IN CONVEYORS
The main aim is to optimize the mechanical maintenance and improve the operational
efficiency of conveyors especially belt conveyors .Some repeated problems of belt
conveyors (rock phosphate conveyor-R conveyor, gypsum conveyor –G conveyor).By
comparing the problems occurred in the R-conveyors as well as G conveyors ,it is
found that the following failures occurs continuously in the G- conveyors.
Belt problem
Bearing damaged
Connecting chain broken
6.4 ANALYSIS
By analyzing the above 2 cases it is found that the continuous failure of G –conveyor
is due to two reasons
1. The traces of phosphoric acid contain in the byproduct gypsum.
2. Exposure of G-conveyor into atmosphere.
These two reasons will lead to corrosion of materials. We can reduce this corrosion by
reducing the exposure of G-conveyor to atmosphere and also by proper filtration of
phosphoric acid.
6.5 SUGGESTION
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We have to design proper roof covering for the G- conveyor to prevent the
atmospheric exposure as in case of R-conveyor. The length of G-conveyor is around
120 meters and the material for covering is aluminum.
There is another solution of reducing the load on the belt either by increasing the
support by increasing the number of roller in effective contact. Secondly, the slope on
the G3 conveyor can be decreased by increasing the height at the G2 side, but this
suggestion is not practical anyhow.
Fig:6 Conveyor Belt
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ANSYS REPORT AFTER ANALYZING THE CURRENT DESIGN OF THE CONVEYOR BELT DESIGN
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FIGURE 7Model (A4) > Static Structural (A5) > Remote Force
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
FIGURE 8Model (A4) > Static Structural (A5) > Remote Force > Figure
Solution (A6)
TABLE 7Model (A4) > Static Structural (A5) > Solution
Object Name Solution (A6)
State Solved
Adaptive Mesh Refinement
Max Refinement Loops 1.
Refinement Depth 2.
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TABLE 8Model (A4) > Static Structural (A5) > Solution (A6) > Solution Information
Object Name Solution Information
State Solved
Solution Information
Solution Output Solver Output
Newton-Raphson Residuals 0
Update Interval 2.5 s
Display Points All
TABLE 9Model (A4) > Static Structural (A5) > Solution (A6) > Results
Object Name Total Deformation Equivalent Stress
State Solved
Scope
Scoping Method Geometry Selection
Geometry All Bodies
Shell Top/Bottom
Definition
Type Total Deformation Equivalent (von-Mises) Stress
By Time
Display Time Last
Calculate Time History
Yes
Identifier
Use Average Yes
Results
Minimum 0. mm 0. MPa
Maximum 1.4995e-008 mm 9.1031e-007 MPa
Minimum Occurs On convers1
Maximum Occurs On belt11 rollersupportbeam1
Information
Time 1. s
Load Step 1
Substep 1
Iteration Number 1
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FIGURE 9Model (A4) > Static Structural (A5) > Solution (A6) > Total Deformation > Figure
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
FIGURE 10Model (A4) > Static Structural (A5) > Solution (A6) > Equivalent Stress > Figure
Material Data
Structural Steel
TABLE 10Structural Steel > Constants
Density 7.85e-009 tonne mm^-3
Coefficient of Thermal Expansion 1.2e-005 C^-1
Specific Heat 4.34e+008 mJ tonne^-1 C^-1
Thermal Conductivity 6.05e-002 W mm^-1 C^-1
Resistivity 1.7e-004 ohm mm
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TABLE 11Structural Steel > Compressive Ultimate Strength
Compressive Ultimate Strength MPa
0
TABLE 12Structural Steel > Compressive Yield Strength
Compressive Yield Strength MPa
250
TABLE 13Structural Steel > Tensile Yield Strength
Tensile Yield Strength MPa
250
TABLE 14Structural Steel > Tensile Ultimate Strength
Tensile Ultimate Strength MPa
460
TABLE 15Structural Steel > Alternating Stress
Alternating Stress MPa Cycles Mean Stress MPa
3999 10 0
2827 20 0
1896 50 0
1413 100 0
1069 200 0
441 2000 0
262 10000 0
214 20000 0
138 1.e+005 0
114 2.e+005 0
86.2 1.e+006 0
TABLE 16Structural Steel > Strain-Life Parameters
Strength Coefficient
MPa
Strength Exponent
Ductility Coefficient
Ductility Exponent
Cyclic Strength Coefficient MPa
Cyclic Strain Hardening Exponent
920 -0.106 0.213 -0.47 1000 0.2
TABLE 17Structural Steel > Relative Permeability
Relative Permeability
10000
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TABLE 18Structural Steel > Isotropic Elasticity
Young's Modulus MPa
Poisson's Ratio Temperature C
2.e+005 0.3
ANSYS REPORT AFTER ANALYZING THE MODIFIED CONVEYOR BELT DESIGN
Solution (A6)
TABLE 19Model (A4) > Static Structural (A5) > Solution
Object Name Solution (A6)
State Solved
Adaptive Mesh Refinement
Max Refinement Loops 1.
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Refinement Depth 2.
TABLE 20Model (A4) > Static Structural (A5) > Solution (A6) > Solution Information
Object Name Solution Information
State Solved
Solution Information
Solution Output Solver Output
Newton-Raphson Residuals 0
Update Interval 2.5 s
Display Points All
TABLE 21Model (A4) > Static Structural (A5) > Solution (A6) > ResultsObject Name Equivalent Stress Total Deformation
State Solved
Scope
Scoping Method Geometry Selection
Geometry All Bodies
Definition
Type Equivalent (von-Mises) Stress Total Deformation
By Time
Display Time Last
Calculate Time History Yes
Use Average Yes
Identifier
Results
Minimum 0. MPa 0. mm
Maximum 1.6718e-005 MPa 6.2095e-008 mm
Minimum Occurs On convers1
Maximum Occurs On Part17^totalconverafterfailedl Part24^totalconverafterfailedl
Information
Time 1. s
Load Step 1
Substep 1
Iteration Number 1
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
FIGURE 11Model (A4) > Static Structural (A5) > Solution (A6) > Equivalent Stress > Figure
FIGURE 12Model (A4) > Static Structural (A5) > Solution (A6) > Total Deformation > Figure
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
Material Data
Structural Steel
TABLE 22Structural Steel > Constants
Density 7.85e-009 tonne mm^-3
Coefficient of Thermal Expansion 1.2e-005 C^-1
Specific Heat 4.34e+008 mJ tonne^-1 C^-1
Thermal Conductivity 6.05e-002 W mm^-1 C^-1
Resistivity 1.7e-004 ohm mm
TABLE 23Structural Steel > Compressive Ultimate Strength
Compressive Ultimate Strength MPa
0
TABLE 24Structural Steel > Compressive Yield Strength
Compressive Yield Strength MPa
250
TABLE 25Structural Steel > Tensile Yield Strength
Tensile Yield Strength MPa
250
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
TABLE 26Structural Steel > Tensile Ultimate Strength
Tensile Ultimate Strength MPa
460
TABLE 27Structural Steel > Alternating Stress
Alternating Stress MPa Cycles Mean Stress MPa
3999 10 0
2827 20 0
1896 50 0
1413 100 0
1069 200 0
441 2000 0
262 10000 0
214 20000 0
138 1.e+005 0
114 2.e+005 0
86.2 1.e+006 0
TABLE 28Structural Steel > Strain-Life Parameters
Strength Coefficient
MPa
Strength Exponent
Ductility Coefficient
Ductility Exponent
Cyclic Strength Coefficient MPa
Cyclic Strain Hardening Exponent
920 -0.106 0.213 -0.47 1000 0.2
TABLE 29Structural Steel > Relative Permeability
Relative Permeability
10000
TABLE 30Structural Steel > Isotropic Elasticity
Temperature C Young's Modulus MPa Poisson's Ratio
2.e+005 0.3
CONCLUSION
The stress analysis has been performed in ANSYS v12.
Initially the existing design was evaluated and then the modified design that included the additional support roller was subjected to analysis. The results were obtained as expected i.e. the modified design showed decreased stress in the conveyor belt.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
Therefore, the modified design can be implemented and is sure to give reduced stress in the belt and thereby increasing the life of the belt
CHAPTER 10
SULPHURIC ACID STORAGE IN PAP
Sulphuric acid manufactured at SAP is stored in tank numbers 1201-A to D (4
tanks) near the plant. It is then pumped to storage tank near the PAP and is then
pumped to NPK and PAP according to their requirement.
Currently acid is pumped through A 6” diameter pipe from 1201-A tank in
SAP to H2SO4 day tank near PAP. The approximate length of that pipe is 250m. From
the tank near PAP, acid is then pumped to PAP attack tank through 4” pipe of length
120m to NPK, two lines of 4” and 135m length is used to pump the acid in which one
is kept as spare. Provisions are therefore direct supply of acid from main line to both
PAP and NPK line without going to the tank. It is noticed that the shell thickness of
the tank is below the safety limit. Replacement of tank will take long time causing
decline in production capacity.
Proposal:
The deteriorated H2SO4 tank can be eliminated by implementing the following
suggestions:
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
Provide direct connection from main tank to attack tank are shown in figure there by
eliminating the pump and the line from current storage tank to attack tank(120m, 4”
diameter).
To fulfill the acid requirement of NPK plant, a line can be laid from tank 1201-D in
SAP to NPK as shown in figure using the 4” pipe used to carry acid to PAP attack
tank and also using the spare line currently provided. Pumps currently used at storage
tank, PAP can be used for the proposed line.
Benefits:
By implementing the above suggestions we can ensure the efficient supply of acid to
both PAP and NPK plant. It eliminates the maintenance of the existing tank for the
construction of new line is available we can considerably decrease the laying cost.
This is comparatively economical both financial wise and efficiency wise than
constructing or fabricating new tank.
CHAPTER 11
CONCLUSION
The study of various machinery present at the FACT-CD was performed. The
report was prepared. The conveyor belt problem was analyzed in Ansys v12 and the
modified design was accepted. The study was conducted in various other parts also.
Remedies were proposed for them as well.
Operational efficiency could be achieved if the availability and reliability of
machinery is ensured.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 12
SCOPE FOR FURTHER STUDY
The optimization of mechanical maintenance helps in increasing the
operational efficiency of plant by decreasing the down time and ensuring availability
of machinery throughout the production cycle. Hence it is very important to optimize
the maintenance practices. We have made a detailed schedule for the optimization in
phosphoric acid plant of FACT Cochin Division. Based on these data further study
can be made as the objective of any organization efficiency at lower expenses.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 13
LIMITATION OF THE STUDY
FERTILIZERS AND CHEMICALS TRAVENCORE LIMITED is a very old
company. Its plant designs have been modified many times to cope with the increase
in production requirements and hence the equipment available there has been replaced
many times. So the proper record of machinery used at various positions is not
available at the plant. To make permanent list of equipment details is a difficult task
unless the entire system is computerized. The lack of proper data regarding many
types of equipment was a limitation during this study.
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE
CHAPTER 14
REFERENCES
• MAINTENANCE HISTORY RECORD OF EQUIPMENTS AT FACT-CD
• INVENTORY OF EQUIPMENTS AT FACT-CD
• KUBOTA METAL CORPORATION, ONTARIO ALLOY DATA SHEET
04/91
• http://www.engineeringtoolbox.com/metal-corrosion-resistance-d_491.html
• http://www.prayon.com/en/professional/equipments/design-development.php
• www.prayon-profile.com
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Optimization Of Mechanical Maintenance In Phosphoric Acid Plant SNGCE