4.project report

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.

1

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.

2


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.

3


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.

4


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.

5


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.

6


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.

7


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

8


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

9


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

10


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

11


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.

12


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.

13


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


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

14


14th compartmentName plate is not available


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

15


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


Date COMPLAINTS REPAIR DONE26/2/11 Agitator broken Agitator replaced10/10/11 Agitator broken Agitator replaced


Date COMPLAINT DEFECTS

REPAIR DONE

26/2/11 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.

16


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

17


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

18


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.

19


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

20


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

21


ANSYS REPORT AFTER ANALYZING THE CURRENT DESIGN OF THE CONVEYOR BELT DESIGN

22


FIGURE 7Model (A4) > Static Structural (A5) > Remote Force

23


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.

24


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

25


FIGURE 9Model (A4) > Static Structural (A5) > Solution (A6) > Total Deformation > Figure

26


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

27


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

28


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.

29


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

30


FIGURE 11Model (A4) > Static Structural (A5) > Solution (A6) > Equivalent Stress > Figure

FIGURE 12Model (A4) > Static Structural (A5) > Solution (A6) > Total Deformation > Figure

31


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

32


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.

33


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:

34


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.

35


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.

36


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.

37


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

38


http://www.prayon-profile.com/

http://www.prayon.com/en/professional/equipments/design-development.php

http://www.engineeringtoolbox.com/metal-corrosion-resistance-d_491.html

4.project report

Documents