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COST EFFECTIVENESS OF MINERAL WOOL INSULATION Vs PERLITE INSULATION
PROJECT REPORT
Submitted by
DIPU.K.SHAJI GITHU BABU VARUN KUMAR. T.K VIMAL MENON
ABSTRACT
The main objective of this project is to make the cost effectiveness analysis of the system of the thermal insulation of the pipe lines in petrochemical plant which carries steam. In a chemical plant maintaining temperature of fluids in different pipe lines assume greatest importance as each process is performed at particular temperature.
The project work was carried out in Hindustan Organic chemicals located at Ambalamugal, Kochi, which is public limited company manufacturing Phenol, Acetone and Hydrogen peroxide.
Steam is produced in a high pressure boiler at the rate of 20 tones/hour. The hot steam is conveyed through thermal insulated pipes for services such as steam tracing, heating etc. Heat loss from the steam passing through pipes is prevented by wrapping the pipe with mineral wool. This existing arrangement was not found to be effective in preventing heat loss from pipes due to various reasons. We were therefore assigned the of designing an insulation system for particular steam line carrying with a suitable insulating material with economy and effectiveness both equally in view.
The first step of our project is to make a thorough study of the existing including the properties of the materials used and their shortcomings. Next step is to find out an alternative material which should have better properties and to revive the method of application of the same, aiming at heat conservation and ultimate economy in running. This calls for a detailed study of properties and behavior of a number of thermal insulating materials economically available at present and to the right and suitable one for our application. A detailed study of the providing insulation to pipes is to be carried out before final is made. Care has to be taken into account, so that the selected material is available without scarcity.
LIST OF TABLES
TABLE 1 INSULATION TYPES AND APPLICATIONS
TABLE 2 TYPES OF INSULATION MATEIAL USED
TABLE 3 THERMAL CONDUCTIVITY OF THE MATERIAL
TABLE 4 COST DETAILS FOR MINERAL WOOL
TABLE 5 THERMAL CONDUCTIVITY OF PERLITE
TABLE 6 COST DETAILS FOR PERLITE
TABLE 7 STEAM LINE DESCRIPTIONS
TABLE 8 OBSERVATIONS
TABLE 9 ECONOMICAL THICKNESS FOR 3 INCH PIPE
TABLE 10 ECONOMICAL THICKNESS FOR 2 INCH PIPE
TABLE 11 COMPARISON OF HEAT LOSS OF BOTH
SYSTEMS
TABLE 12 COST OF PERLITE INSULATION
LIST OF DIAGRAMS
FIG 1 PLANT LAYOUT
FIG 2 PIPING INSULATION WITH TRACING
FIG 3 PIPING WITH METAL PROOFING
FIG 4 PIPING VERTICAL EXPANSION JOINTS
FIG 5 STEAM LINE CIRCUIT
LIST OF GRAPHS
TEMPERATURE Vs HEAT LOSS
TEMPERATURE DIFFERENCE Vs HEAT TRANSFER
THICKNESS OF INSULATION Vs HEAT TRANSFER
AIR VELOCITY Vs PERCENTAGE INCREASE IN HEAT
LOSS
TEMPERATURE Vs THERMAL CONDUCTIVITY ECONOMICAL THICKNESS Vs TOTAL COST
NOMENCLATURE
Top = operating temperature in Deg c
Tamb = ambient temperature in Deg c
hin = heat transfer coefficient of pipe in watts/m2 k
hout = heat transfer coefficient of aluminium in watts/m2 k
Re = Reynolds number
Pr = Prandl number
Nu = nusselt number
L = length of pipe in m
r = outer radius in m
rl = inner radius in m
K = thermal conductivity in w/mk
Ql = heat transfer of first pipe with mineral wool insulation in kw
Q2 = heat transfer of second pipe with mineral wool insulation in kw
Q3 = heat transfer of third pipe with mineral wool insulation in kw
Q4 = heat transfer of fourth pipe with mineral wool insulation in kw
Q5 = heat transfer of first pipe with perlite insulation in kw
Q6 = heat transfer of second pipe with perlite insulation in kw
Q7 = heat transfer of third pipe with perlite insulation in kw
Q8 = heat transfer of fourth pipe with perlite insulation in kw
TABLE OF CONTENTS
CHAPTER TITLE PAGE
ABSTRACT LIST OF TABLE LIST OF FIGURE LIST OF GRAPH NOMENCLATURE
1 BRIEF PROFILE OF THE ORGANISATION 1
1.1 COCHIN UNIT 2
1.2 AWARDS 3
1.3 PLANT LAY OUT 4
2 INTRODUCTION 7
2.1 INSULATION AN OVERVIEW 8
2.2 SCOPE 9
2.3 DEFINITION 10
2.4 GENERAL REQUIRMENTS 11
3 LITERATURE REVIEW 13
3.1 TYPES OF THERMAL INSULATION 14
3.2 INSULATION TYPES AND APPLICATIOS 17
3.3 THERMAL INSULATION PROPERTIES 17
3.4 INSULATING MATERIALS 20
3.5 PIPING INSULATION DETAILS 23
3.6 PARAMETERS AFFECTING HEAT LOSSES 25
3.7 HEAT LOSS FROM THE BARE SURFACE 25
3.8 HEAT LOSS THROUGH INSULATION 27
3.9 HEAT LOSS FROM CYLINDRICAL SURFACES 30
4 COMPARITIVE STUDY 31
4.1 INTRODUCTION 32
4.2 MINERAL WOOL MATERIAL 33
4.3 PERLITE MATERIAL 36
5 SURVEY METHODOLOGY 40
5.1 INTRODUCTION 41
5.2 CIRCUIT DETAILS 42
5.3 OBSERVATIONS 46
6 CALCULATIONS 47
6.1 CALCULATION OF ENTHALPY 47
6.2 HEAT LOSS CALCULATIONS FO MINERAL WOOL 51
6.3 DETERMINATION OF ECONOMICAL THICKNESS 53
6.4 HEAT LOSS CALCULATION FOR PERLITE 56
6.5 COST OF HEAT SAVED USING PERLITE SYSTEM 59
6.6 COST OF PERLITE INSULATION SYSTEM 60
6.7 PAYBACK CALCULATIONS 61
7
CONCLUSIONS & SUGGESTIONS
62
CHAPTER -1
A BRIEF PROFILE OF THE ORGANIZATION
The organization was in-corporate with a view to Set Up manufacturing of chemical intermediates with the objectives of giving inputs to the development of downstream industrial units in sector like dyes and dye intermediates, drugs and pharmaceuticals, rubber chemicals, laminations, solvents etc. The first unit was set up at Rasayani in Maharashtra which commenced production in 1970. The second unit was started at Cochin in Kerala, which started production in 1987. In the year 1988 a subsidiary company viz Hindustan fluorocarbons Ltd. was commissioned at Hyderabad. The company is presently engaged in the manufacturing of a wide range of petrochemicals. The major products serve as import substitutes.
The organization is a public limited company, which is managed by a board of directors consisting of six members.
The management is assisted by a team of well qualified and experienced professionals in technical financial safety, marketing, legal and other key areas.
COCHIN UNIT
Commissioning of Cochin (phenol and acetone) in 1987 headed another path breaking step of HOC;s entry into the field of petrochemicals. The Cochin plant has an installed capacity of 24,000 TPA of acetone and 409000 TPA of phenol; both are highly versatile organic chemicals. The Cochin unit comprises of three states of plant, Viz.
1. Propylene recovery plant
2. Cumene plant
3. Phenol plant
Universal oil products inc (UOP', USA One of the] world leaders in the field of petrochemicals has supplied the technology for phenol-cumene plant. Detailed engineering for all the plants and also off-site work was done by FEDO and Engineers Indian Ltd. Provided engineering for the propylene plant and Effluent treatment plant.
The company has achieved the ISO 9002 certification for its quality measures in the production process and ISO 14,000 for environmental quality standards. The entire operation of plant is totally Automatic remote controlled. Continuous on-line monitoring of the process results in perfect quality control.
The organization has high tech safety features to minimize hazards. Most modem effluent treatment plant assures complete safety to the environment confirming to international specifications. Latest energy conservation and optimization concepts have been incorporated at the beginning stage. This is the first company to export Phenol and Acetone from India.
State pollution control board has awarded the company with the certificate of merit.for pollution control. Cochin plant was awarded with the best pollution control measures among chemical plants in the state of Kerala.
AWARDS
1) ISO 9002 from BVQI in the year 1994.
2) Best productivity awards in 1989-91,91-92,94-95 (by Kerala state productivity council).
3) Safety awards (by National safety council) 1989,90,91,93,94,95,96,97,98,99.
4) Pollution control measures 1988-89,95,96,97.
5) ISO 14000 in the year 1999 for Environmental continues production.
1. H2O2 plant
2. Main tankage
3. H2 plant 1
4. Compressor house
5. DM plant
6. Boiler
7. H2 Plant 2
8. North Tankage
9. Fractionation section
10. Hot oil plant
11. Tar cracking plant
12. Cumox plant
13. Cumene plant
14. South tankage
15. Cumene storage
16. Effluent treatment plant
17. Cumene storage
18. Main receiving station
19. Captive power plant
20. Main control room
21. Propylene plant
22. Propylene storage
23. LPG storage
24. Cooling tower
25. Administrative block
26. Pre-treatment plant
27. Water storage
28. Emergency escape road.
CHAPTER -II INTRODUCTION
INTRODUCTION
Heat is a form of energy, which is required to perform many activities. But like other forms of energy, heat energy also travels from one place to another. The transfer to heat differs from matter to matter. There are three ways in which heat can be transformed from one point to other.
1. Conduction
2. Convection
3. Radiation
Heat transfer from body to body contact
Heat transfer by actual movement of particles
Heat transfer without need of particles in the medium.
Electric power generation and steam production for diverse industrial application rely on the convention of potential energy in a fuel into useful work. It is estimated that only 40% of the total potential energy in the fuel is converted into useful work. Heat insulation materials make a major contribution towards this capture of this percentage of total potential energy.
INSULATION AN OVERVIEW
Thermal insulation is a material, which retards the flow of heat. It is used as a barrier between two bodies at different temperature either to reduce heat loss from hotter body or to prevent heat entry into a cooler body. As heat is energy, the study of thermal insulation is the study of "Conservation of energy". As energy has a monetary value insulation conserves money. Functions
1. Conserve energy
2. Control temperature
3. Control transfer of energy
4. Retard freezing
5. Control fire
Purpose
The purpose to use the heat insulation for plants is the prevention of at from useless radiation to save fuel, power and heat energy. To accomplish this purpose, 100% of adiabatic property of heat insulation should be displayed.
SCOPE
Insulation materials are usually composed of filaments generally circular in cross section or in the from of slabs. Generally the diameter of the insulation is greater than the outer diameter of the pipe and of length considerably greater than the diameter.
The insulation material may be of signal layered or of composite filaments. The materials used for manufacturing thermal insulation are usually fibrous, organic naturally occurring of manufactured.
The thermal insulations are generally installed in refinery equipment and piping vessels, equipments, heat exchangers, pipes and fittings, flues, ducts, tanks, valves, steam generator casing, fixture casing, steam turbines etc. operating between a particular temperature limit.
The flowing are the several purpose of thermal insulation
1. the maintenance of process temperatures.
2. The conservation of energy when a loss of heat is not desired.
3. The protection of personnel from heat.
4. Steam of electric heat tracing.
5. Noise attenuation.
DEFINITION
"Thermal insulation is used as shielding from excessive temperature and heat
losses".
"According to thermodynamics when two systems are brought into contact through some kind of wall, energy transfers, such as heat and work takes place between them" Here the heat transfer takes place by the ode of conduction.
Heat conduction is the mode of heat transfer accomplished via two Mechanisms.
1. By molecular interaction, where by the energy exchange takes place by kinetic motion or direct impact of molecules.
2. By drift of 'free' electrons as in the case of metallic solids.
Definitions of all the terms used are in accordance with then India Standard specifications.
GENERAL REQUIREMENTS 1. Needs
Thermal insulation shall be provided for all vessels, equipments, heat exchangers, pipers and fittings. Etc. containing fluids or vapours for which it is necessary to
a. Conserve heat
b. Maintain temperature for process control.
c. Provide for personnel protection.
2. Protection of materials during storage.
Insulation materials shall be protected against the weather at all times from delivery to finish cladding. Decking and covering with tarpaulins alone are not considered efficient protection from the weather. Insulation materials shall at no time be stacked directly on the ground.
3. Hydrostatic Testing
If the insulation work proceeds in advance of hydrostatic testing and inspection, welded and mechanical joints shall be left insinuated for a length of at least 300mm on either side. Such joints shall be insulated after the testing and inspection is over. The insulation of flanges shall not be done until pipelines and vessels have reached the operating temperature and the flanged joints have been proved to be light. After that the insulation can be applied.
4. Anti Corrosive paint
The surface to be insulated after being thoroughly cleaned and wire brushed a hall be given one coat of anti-corrosive paint applied by brush before the commencement of insulation application.
5. Insulation for personnel protection
Piping and equipment that are not insulated but have a surface temperature exceeding 50C shall be insulated for personnel protection when
i. The bottom of the pipe in 2 meters and less from the ground or permanent
working floor or platform or walkway.
ii. .The piping and equipment, or parts there of are within 600mm from a
platform, floor or walkway.
Piping and vessels, to be insulated if the temperature in the outermost surface in 50 C or more. Vessels or equipments in horizontal position, which are to be insulated for personnel protections, shall be fully insulated when the outside diameter is less than 1250 mm and to a height of 2 Meters form the floor working platform.
CHAPTER - III LITERATURE REVIEW
TYPES OF THERMAL INSULATIONS
There are various types of thermal insulations available. The selection of thermal insulation depends upon the
a. Equipment to be insulated
b. Purpose for which insulation in needed.
Some of the types of thermal insulation commonly used are:
1. Blanket Insulation
A flexible insulating material composed of felted fibrous material without binder, but reinforced with confining media .
2. Block Insulation
Straight or segmental blocks of board insulation with or without facing and with or without attachment for application puipose.
3. Calcium Silicate insulation
Insulation composes of hydrated calcium silicate with small quantity of material
fibers.
4. Composite Insulation
Multi layer insulation in which different layers have different properties and characteristics.
5. Fibrous Insulation
Insulation material composed of filaments generally circular in croos-section and of length considerably greater than the diameter.
6. Pipe Insulation
It many be block form, moulded form, flexible form, strip form or in forms.
a. Block Form : Segmental blocks of rigid thermal insulation materials un faced or
the exterior faced with a protective material. For applications are received.
b. Moulded (performed) Form: Rigid or flexible cylinder of thermal insulation
material, either not split or suitable split longitudinally, either enfaced or faced on
the exterior with a protective materials, for application as received and generally
furnished with fixing bands.
c. Flexible Form : Mat or blanket insulation supplied in exact width to fit round any
standard diameter pipe.
d. Strip Form: Mat or blanket insulation in the form of a strip between 75 to 150 mm
width for bandage - wise applications.
e. Rope Form : A loosely braided sleeve of asbestos, Glass yam on wire packed with
asbestos fibers or mineral wool
7. Multi- layer insulation
Insulation comprising more than one layer of insulating material.
8. Hot Face insulation
Insulating materials which may be exposed directly to hot gases or high temperature areas.
Apart from this, some other types of thermal insulation used
1. Backing insulation
2. Batt insulation
3. Board insulation
4. Cellular insulation
5. Flexible insulation
6. Loose fill insulation
7. Mat insulation
8. Powder insulation
9. Rigid insulation
10. Sprayed insulation
INSULATION TYPES AND APPLICATIONS
SI. No Type Application
1 Urethane foam Hot and cold pipes
2 Cellular glass blocks Tanks and pipes
3 Fiber-glass blankets Tanks and equipment
4 Fiber-glass preformed shapes Piping
5 Elastomeric sheets Tanks
6 Fiber-glass mats Pipe and pipe fittings
7 Elastomeric performed shape Pipe and fitting
8 Fiber glass with vapour barrier blanket Refrigeration lines
9 Fiber-glass boards Boilers, tanks, heat exchangers
10 Cellular glass blocks and boards Hot piping
11 Mineral fiber blankets Hot piping
12 Mineral wool blocks hot piping
13 Calcium silicate block, boards Hot piping boilers
14 Mineral fiber blocks Boilers and tanks
15 Mineral fiber preformed shapes Hot piping
THERMAL INSULATION PROPERTIES
There are certain properties, which should be taken into account during selection of insulating material during installation
1. Low Conductivity
The coefficient of thermal conductivity should be less for a good thermal insulation, so a s to prevent the loss of heat through the insulation.
2. Low water absorption
i. Once water is absorbed into the insulation even if its conductivity is extremely
low, the heat conductivity of the materials is increased and the diabolic effect is
extremely reduced so as to make the heat conductivity of the materials close to
that water 30.5 kcal/m.h.c
ii. Absorptions of water inside the insulation, causes the outer portion of the pipes to
get rusted.
3. Non-corrosive
The insulation materials should be free form chloride and other corrosive substances. Ordinary stainless steel pipes and equipments is very susceptible to stress corrosion cracking temperatures above 60c, which may occur due to chloride content present in the insulation
4. Resistance to thermal Stress
In upset conditions there is constant expansion and contraction activities contraction is the property generated from dehydrating the water of crystallization the resultant effects is camber and cracks at the temperature ranges from 200°C to 300°C when expansion is allowed to cool down and the parts contract and are resorted to the original state, thus the resorting property.
5. Fire Resistance
The thermal insulation should be fire resistant and should be non combustible. It is should have very low thermal diffusivity.
6. Acid & Alkali Resistance
The thermal insulation should be resistance to concentrated acid attacks such as Sulphuric acid hydrochloric acid & nitric acid.
7. Pollution free
The thermal insulation material should not pose any health hazards.
8. Consistent performance
The thermal insulation should retain its shape and thermal conductivity throughout its life and should not be affected by weather conditions.
9. Easy Insulations
The thermal insulations must be easily installed and should be easily removed for maintenance work
10. Strength.
The installed thermal insulation should be able to withstand human foot traffic and in-service thermal and mechanical vibrations.
INSULATING MATERIALS
The insulating materials and protective covering shall be new and fresh, incombustible rot-proof non-hygroscopic and shall be guaranteed to withstand continuously and without deterioration the maximum temperature to which they will be subjected under the specified applications. The insulating material and any combustion, with water or moisture to form substances which are more actively corrosive to the applied surface than water or moisture of form substance, which are more actively corrosive to the applied surface than water or moisture alone. The materials shall not offer substance to fungus or vermin and must not pose health hazard.
The insulation materials to be used for insulation of pipes, vessels, heat exchangers, equipments etc. Shall be mineral wool in the form of preformed pipe sections or mattresses subject to limitations of carbon steel surface operating in the temperatures ranges of 25 c - 700 c and stainless steel surface operating in temperature range of 25 c and 600 c.
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Piping insulation with electric heat Tracing
Insulating Cement
The insulating cement will have the same composition as that of main insulating materials to which it is applied. It shall be capable of withstanding the same t c.
Finishing Cement
The finishing cement, when used shall be made of inorganic fibers and Portland cement so that it will set to hard finish. The application density for finishing cement shall be 1050 kg/cu.m to 1100 kg/cu.m.
Sheeting Materials
The sheeting material for all insulated piping and equipment shall be aluminum / galvanized steel.
Binding And Lacing Wire
Binding or lacing wire should be made up of galvanized steel wire where interface temperature is 400 c or more, binding wire will be stainless steel wire.
Straps And Bands
All straps and bands shall be of galvanized steel. For securing aluminum material, stainless steel or anodized aluminum band shall be used.
Screws
It may be of self-tapping type and shall be of galvanized materials.
PIPING INSULATION DETAILS
External surfaces of the pipe to be insulated shall be cleaned by wire brushing to remove dirt and lose scales. If painting is required it is to be done before laying the insulation.
All pipes and supports shall be permanently set before insulation is started. Disturbed pipes and supports shall be restored to their original location and alignment when the insulation is complete.
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Insulation is the form of preformed pipe sections shall be applied over the pipe without the use of spacer rings. When mineral wool mattresses are used they shall be wrapped around the pipes without any un4er layer. On top of each layer wire'-netting shall be applied and tightly butted against each other so that fibers interlock both along the longitudinal and circumferential joints.
At uninsulated flanges, pipes line insulation shall be stopped off at suitable distance from the flanges, so that flange bolts can be withdrawn without disturbing insulation
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Piping Vertical Expansion joints Metal Sheet Finish
All Pipes shall be covered by a specified sheating to the outside of insulation with 25 mm circumferential and longitudinal overlaps. The overlapping shall be grooved so as to prevent ingress of water into insulation. The sheating shall be secured to themselves by self tapping screws. Sheating joints need not nsecessarily occur at spacer rings.
PARAMETERS AFFECTING HEAT LOSSES
Heat is a form of energy, which flows from a body of higher temperature to a body of lower temperature. So whenever there comes a temperature difference heat flow takes place.
There are parameters which effects the rate of heat flow. They are:
1. HEAT LOSES FROM BARE SURFACES
The heat losses from bare surface at different temperature can be shown graphically.
Heat
loss
Graph 1: Temperature Vs heat Loss
The graph shows the relationship between heat loss taking place between bare surface and insulated surface.
The heat losses so obtained on graph are average for still air conditions. Variation of heat loss may take places between various pipe sizes and different absolute temperature of surroundings, but these variations are small compared with that caused at comparatively at low air velocities.
The graph also illustrate the necessity of providing insulation.
Effect of Air Velocity On Loss From Bare Surfaces
The rate of heat loss from a surface maintained at constant temperature is generally increased by air circulation. This is shown graphically
Heat transfer
Temp. Difference
Graph 2 : Temp Difference Vs Heat Transfer
Incase of well insulated surface increase in losses caused by air circulation ae small compared with increase in bare fittings
Heat losses bare fittings
Very often even when pipes are thoroughly insulated, flanges and fittings ae left bare because of belief that losses from the parts are not so large however it is estimated that pair of 10 inch standards flanges having an area of 343 fts would lose at 100-16 steam pressure 9ie.,) an amount equivalent to more than 1 ton coal / year.
2. HEAT LOSS THROUGH INSULATIONS
It was found that heat loss will take place even though if the surface are provided with an effective insulation. But the heat loss taking plae from such surface will be very negligible when compared to that of bare surfaces.
The rate at which heat loss takes place is more, less the heat loss and vice versa. This relationship can be demonstrated graphically.
Heat transfer
Temp of hot surface 1600 cl
Thickness of insulation
Graph 3: thickness Vs Heat Transfer
Additional savings by thicker insulation will not be large when temperature and value of heat demand the use of greater thickness. The curve shows the loss per degree per temperature difference. The total losses can be obtained by multiplying the value of curves by temperature difference.
Effect of air velocity on heat losses from insulated surfaces.
In the case, of well insulated surfaces, the heat losses due to air velocity are very small compared with the increase in bare pipes or surfaces. This is due to the fact that, the air flowing over the surface of insulation can increase only the rate of heat transfer from surface to air and cannot change the internal resistance to heat flow inherent in the insulation itself. The effect of an insulated surface will depend upon :
1. Internal resistance or resistance offered by the insulation materials
2. Surface resistance
3. Temperature of surroundings and hot surface.
The internal resistance of a material to heat flow depends upon the :
a) Thickness V
b) Thermal conductivity' k' For flat surfaces both these vary indirectly. Total heat transmitted H = UA(Th - Tc) Where,
U - Over all rate of heat transfer co-efficient
A - Area of surface
Th - Temperature of hot surface
T - Temperature of cold surface
When heat flows through solid material and than out into air, a resistance to heat flow is encountered at the surface separating the solid from air Less heat will flow if no resistance were offered at that point. This is called surface resistance. Surface resistance will be small when compared to internal resistance of materials in connection with efficient insulation.
Effort of thickness of insulation on rate of heat transfer
The heat loss also depends on insulation thickness. Both thickness and heat loss are inversely related (i.e.) the thickness of air insulation is therefore to cool the surface of insulation to a temperature than it would have under still air conditions, thereby increasing temperature drop through insulation.
Bare surface
Air velocity
Graph 4 : Air Velocity Vs Percentage increase in Heat loss.
In case of surface located out doors, the combined effect of wind and rain may bring the surface temperature practically down to air temperature. The effect of air circulation on losses through insulations are based on flow of air over the surface of insulation and applied to cases where insulation is tightly sealed.
3. HEAT LOSS FROM CYLINDRICAL SURFACES (PIPES)
In case of cylindrical surfaces increasing thickness supplies additional resistance through which heat must flow but at the same time increase the area of path through which heat may flow.
Heat transfer per unit area of inner surface will be greater for insulation on a curved surface than on flat surface and that the smaller the radius of curvature, the greater will be rate of heat transfer unit of inner surface area
The heat loss per hour per degree difference in temperature per square foot of outer surface of insulation on a pipe or other cylindrical surface is given by
U2
1
r21oge(r2/rl) + l//
Where
rl
External radius of pipe
Radius of outer surface of insulation
U
Rate of heat transfer per hour per temperature per sq ft of
outer surface of insulation
Ul
V21 rlxU2
The rate of heat transfer through two thick insulation on 1 inch pipe is more than twice as great as through the same thickness of 12 inch pipe
CHAPTER -4 COMPARATIVE STUDY
INTRODUCTION
In order to replace the existing thermal insulation material with a new material, a detailed study of comparison is very important. Thermal insulation is a material which retards the flow of heat
The existing thermal insulation material is bonded mineral wool materials It is made from rock slag or glass processed from a molten state into fibrous form and shall be bonded with a suitable binder This material is fibrous and is in the form of mattress.
The new material which is to be replaced is a perlite material. It consists of millions of vitrified cells and is available in the shape of blocks. There are several important features for the perlite material out of which low water absorption and resistance to corrosion is outstanding.
MINERAL WOOL MATERIAL Description
The bonded mineral wool material shall ha made from rock stag Or glass processed from a molten state into fibrous form and shall be bonded with a suitable binder. Bonded mineral wool can be used with a suitable facing material for a temperature range of -50°c to 700°c.
Composition
The fibrous form insulation material shall be ductile, tough and extremely fine with fibre diameter varying from 3 to 5 microns. There shall be no setting of the fibres over an extended period of use.
Density
The applied density of mineral wool shall be as given below Operating temperature from 25°c to 500°c.
1. Unbonded mineral wool
120k g/m3
2 Lightly resin boned
Mineral wool mattresses
and preformed pipe
sections.
150 kg/m
3
Operating temperatures from 501° c to 700"c.
Unbonded mineral wool
200/kg/m3
2
Lightly resin bonded mineral wool
Mattresses and performed pipe section
150k g/m3
The bulk density of the ending facing will be normally within the following ranges and may be suitable for use unto a particular hot face temperature as given below.
Group Bulk Density Maximum recommended hot face temperature
Group 1 12-50 Kg/m3 Upto 250°c
Group 2 50-80 Kg/m3 Upto 400°c
Group 3 80-120kg/m3 Upto 550°c
Group 4120-160 kg/m3 Upto 750°c
The thermal conductivity shall be furnished at mean test temperature ranging from 50'c to 400'c in steps at different applied densities.
The thermal conductivity or k-value of the material shall not exceed the values given below.
Mean temperature c Thermal conductivity w/M deg
Group 1 Group 2 Group 3 Group 4
50 0.49 0.43 0.43 0.43
100 0.69 0.52 0.52 0.52
150 0.95 0.64 0.62 0.62
200 - 0.78 0.73 0.68
250 - 0.93 0.84 0.80
300 - 1.10 0.95 0.90
The insulation material shall be chemically inert and shall be rot and vermin proof. The finished mineral wool mattresses or pipe section shall not contain more than 10 ppm of chlorides and shall be packed in polythene bags for shipment to worksite.
The mineral wool fibers, both lighted resin bonded and unbonded shall be made into mattresses by laying the fibers with machines so as to ensure uniform density and thickness of the mattresses. The mattresses shall then be machine stitched along with the backing of specified wire-netting. The mattresses shall retain their form under ordinary handling conditions.
Cost Details for Mineral Wool
S.No Description 3 inch pipe Rs/m 2 inch pipe
Rs/m
1 Insulating material 107.24 96.85
2 Aluminum sheet 106.06 76.45
3 Screws 2.65 2.65
4 Labour 114.05 114.05
PERLITE MATERIAL
Perlitemp is a high temperature insulation, precision molded into pipe and block shapes. Its principal ingredient - expanded perlite is one of best of all the known naturally occurring insulating materials. It's characteristics structure consists of millions of vitrified cells. Through a property process these particles are bonded together with special inorganic binders and reinforcing fibres, molded and baked. The final product has very:
a) Low thermal conductivity
b) Non-corrosive
c) Asbestos free
d) Moisture and fire resistant
e) Light in weight
f) Easy installation
Important Features
The following are the important features
a) Low conductivity
Of all insulating material available, perlitemp has one of lowest coefficient for the use in power generation and process industries.
b) Non-Corrosive
The high content of sodium ions acts as a corrosion inhibitor and offers an excellent protection against stress corrosion of stainless steel.
c) Low water absorption
Perlitemp repels moisture in a 24 hrs total immersion in water. It typically absorbs less than 5%.
d) Fire resistance
In direct contact with the flame, the outside surface of insulation vitrifies and acts as additional protection for the valuable piping equipment thus preventing any bum through.
e) Mechanical resistance
It maintains its mechanical integrity in most demanding conditions of use
f) Recoverable
In maintenance work, when insulation needs to be dismantled, this can be recovered which is not possible by mineral wool.,
Physical Properties
Density -215kg/cu-m
Flexural strength
- 330KN/m2 (min)
Compressive Strength
- 540KN/m2, 5% compression
Lineral shrinkage
- 0.85% after 24 hours at 650uc
Maximum Service temperature
- 650UC
Thermal Properties
Surface burning characteristic
1. Flame spread - 0
2. 2. Smoke developed - 0
Chemical Properties
¢ It contain no asbestos
¢ Resists acids and alkallies
Environmental Properties
¢ Does not cause any irritation in contact with skin
¢ Non- Carcinogenic material
Graph 5: Temp Vs Thermal Conductivity
CHAPTER - 5 SURVEY METHODOLOGY
INTRODUCTION
For computation of heat losses, economical thickness of insulating material and to decide on the quantity of the materials required, the following data's are required
1. Operating temperature
2. Surface temperature
3. Ambient a temperature
4. Existing thickness of insulation
5. Length of steam lines etc.
The following methodology are used in arriving the dimensions. Determination Of Temperature
The temperature that are to be determined are:
1. Operating temperature (temperature of'steam passing through pipe)
2. Surface or skin temperature (temperature with insulation)
3. Ambient temperature
These temperatures are determined by an instrument known as infra-red thermometer
This instrument uses infra-red rays for finding out the temperature the infra red rays are focused to the place where temperature is to be measured. When these rays and focused, the corresponding temperature will be displayed in LED display. By this,
temperature with and without insulation are taken for different steam lines. Out of values the average value is taken for the calculation purpose.
Determination Of Thickness
The thickness of insulation is measured by pushing the needle ofi the thickness measuring instrument into the material and then measuring the length of needle with a depth gauge.
The thickness measuring instrument consists of 3mm diameter, 200MM long mild steel rod pointed to a sharp conical end. The length of conical portion shall be 2cm. The rod is fitted with a metallic disc 75mrn diameter and 50g in weight which is provided with means of clamping it to the rod.
Push the thickness measuring instrument into the specimen + perpendicular to the plane of the material surface, until its point touches but does not penetrate the underlying surface. Lower the disc gently down the rod until it rests under its own weight at constant level on top of the material and is not pushed into the surface. Clamp the disc in this position and remove the measuringinstrument. Measure the exposed length of the rod to 0. 1 mm with a depth gauge.
CIRCUIT DETAILS
The steam produced from a high pressure boiler which then branches into several sections of different pressures according to the plant requirement The steam line so chosen is the main line coming from the boiler having a pressure of 18.5 kgcm" .
The main line again branches into several sections as shown in the figure The pressure so produced in boiler is 20kgcm2 . The steam coming from the boiler first passes through the flow meter where the pressure is reduced to 18..5 kgcm2. Steam after passing through flow meter is branched and is passed to evaporator. The other section then passes to wash water column ejector system (cumene plant). The remaining steam is then diverted into Hydrogenation ejector and Fractionation section. These sections are interconnected with pipes of different size, specifications etc.
The different working units are designated by codes. The following codes are specified are specified as follows
J3001 - Evaporator (Evaporation section vaccum system)
J2rJ01 - Wash water column ejector system (Cumene plant)
J5001 - Hydrogenation ejector
J4501 - Fractionation ejector
STEAM LINE CIRCUIT
5054-sh-25-lA2A,
4792-SH-50-A2A,
4
9004-SH-A2A,
45001 9003-SH-80-A2A!
44501
2118-SH-40-A2Ai
H3001
1. Boiler
2. Evaporator
3. Wash water column ejector system
4. Hydro generation ejectors
5. Fractionation ejector
J2001
OBSERVATIONS
The table shows that the observation made for the existing thermal insulation (LB mineral wool) in the steam line circuit.
Sl.No. Description OD L ETI MATL OPT AMB.T SURFACE Temp
1 18.5 kg steam main line 88.9 150 50 LB 214 32.3 53.1
2 18.5 kg
steam
J3001 60.3 20 50 LB 214 32.3 50.8
3 18.5 kg line to J4501/5001 60.3 70 50 LB . 214 32.3 47.1
4 18.5 kg line to J4501 60.3 25 50 LB 214 32.3 47.8
Legend:
OD = Outer dia in mm
L = Length in mm
ETI = Existing thickness of insulation in mm
OP.T = Operating temp in deg C
AMB.T = Ambient temp in deg. C
SURFACE TEMP = Surface temperature in deg C
INTRODUCTION
The main objective of the design is the replacement of existing thermal insulation with a new product. It was found that, the existing thermal insulation is less economical, due to the following reasons.
1. High heat loss
2. High water absorption
3. High maintenance cost
4. Less durable
5. High thermal conductivity
It was found that the new material is sufficient enough to overcome the existing thermal insulation. A detailed study of new product was conducted and found to be more effective than the existing one.
The design process involves
1. Heat loss analysis
2. Determination of economical thickness 3 Savings and Payback
HEAT LOSS ANALYSIS
Whenever there is a temperature difference between the surfaces and surroundings, heat loss takes place. Even though, thermal insulation is provided, small amount of heat transfer will take place. The rate of heat transfer will depend on
a) Internal resistance by insulation
b) Surface resistance
c) Temperature if hot surface and surrounds
Oc
Let us consider a layer of insulation which might be installed around a circular pipe as shown in figure. Inner temperature of insulation is fixed at 9h, outer surface is exposed to a convection environment at 9c.
The rate of heat loss taking place through single layered insulation is given as
below
Q ((Top - Tamb)/ (((l/27irL)hin) +(ln(rl/r)/2rtLk)+(l/(27irl2L)hout))
Where,
Q - Heat loss through insulation in w/m.
T01, - Operating temperature of the steam line in °C Tamb - Ambient temperature in °C r - Outer diameter of pipe in cm
rl Outer diameter of layer of insulation in contact with pipe in cm
K Thermal conductivity of insulation (w/mK)
CALCULATIONS
CALCULATION OF HEAT TRANSFER COEFFICIENT
Reynolds number = Re
M =18.5kg/hr
D = 0.08 m
(1) Re=4m(nrcd)
Re = 4xl8.5/(1.5xl0"5x7tx0.08x3600) =5455
The flow is turbulent
(2) Re = 5455
Pr = 1.43
Nu = 0.023xRe° 75xPr°33 = 0.023x5455° 75xl.43°33 = 22.31
(3) d = 0.08 m K =36xl0"3
hin = Nuxk/(d) = 22.31x36xl03/0.08 = 11.36 w/m2k
At d =0.06 m
hin = 15.3w/m2k
HEAT LOSS CALCULATION FOR EXISTING INSULATION (BONDED MINERAL WOOL)
1.18.5kg/ m3 steam main line
The heat loss of steam main line coming from boiler is calculated as follows. The data's are
Working temp (Top) = 214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.098m
Inner radius ® = 0.04m
Length (L) =150m
Thermal conductivity (K ) = 0.078 kw/mk
hin = 15.36 w/m2k
hout - 5 w/m2k
Ql = (Top-Tamb ()/ (((l/2;trL)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout))
=((214-32)/(((l/27rx0.04xl50)xl5.36)+(ln(0.095/0.040)/27txl50x(0.078/1000)+(l/(27ix0.0952xl50)5)) =(182)/(2.33+l 1.6+3.526) = 10.46kw
2.18.5kg/m3 steam main line J3001
Operating temp (Top) =214°c
Ambient temp (Tamb) = 32°
Outer radius (rl) = 0.08m
Inner radius ® = 0.03m
Length (L) = 20m
Thermal conductivity (K) = 0.078 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q 2 - ((Top-Tamb)/ (((l/27irL)hin) +(ln(rl/r)/27tLk)+(l/(27irl2L)hout))
=((214-32)/(((l/27ix0.04x20)xl5.36)+(ln(0.08/0.003)/27ix20x(.078/1000)+(l/(27tx.082x20)5))
= ((182)/(17.26+99.98+4.97)
= 1.48kw
3.18.5kg/m3 steam main line J4501/J5001
Operating temp (T0p) =214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.095m
Inner radius ® = 0.03m
Length (L) = 70m
Thermal conductivity (K) = 0.078 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q 3 = ((Top-Tamb)/ (((l/2;irL)hin) +(hi(rl/r)/27iLk)+(l/(27irl2L)hout))
=((214-32)/(((l/2Ttx0.03x70)xl5.36)+(ln(0.08/0.003)/2Tix70x(0.078/1000)+(l/(27tx0.082x20)5))
= ((182)/((4.93+28.56+4.97))
= 4.73kw
4.18.5kg/m3 steam main line to J4501
Operating temp (Top) =214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.095m
Inner radius ® = 0.03m
Length (L) = 25m
Thermal conductivity (K) = 0.078 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q4 = ((T0p-Tamb)/ (((l/2ra:L)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout)) =((214-32)/(((l/27ix0.03x25)xl5.36)+(ln(0.08/0.03)/27ix25x(.078/1000)+(l/(27tx0.082x20)5)) = ((182)/(13.6+81.6+4.97)) = 1.8 lkw
DETERMINATION OF ECONOMICAL THICKNESS
The required thickness of insulation for any specific application will depend upon the characteristics of insulating material and the purpose of the equipment.
When the sole object is to achieve the minimum total cost, the appropriate thickness is known as economic thickness.
The cost to be considered all the cost of heat losses from insulated surfaces during the chosen evaluation period cost of insulation system during the same period. Any increase in the amount of insulation applied will raise the cost of insulation which will decrease the cost of heat lost.
The sum of these two costs can be shown to lie on g curve with a rather flat region on either side of minimum value representing the economical thickness.
An economic study to determine justified thickness should consider following factors:
1) Hours of operation per year.
2) Fuel cost including labour and maintenance. Efficiency of combustion.
4) Pipe diameter.
5) Operating temperature and ambient temperature.
6) Estimated cost of installed insulation at actual plant site.
7) Amortization period.
8) Heat losses.
In order to determine economical thickness of a particular steam line, 'the following data's are required such as:
1) Heat losses.
2) Cause of heat loss.
3) Total cost compressing of cost of beat lost and insulation cost.
Whenever there will be an increase or decrease in thickness, there will be change in beat losses, cost of heat etc. So in order to judge economical thickness, the total including all coast are to be determined for a range of insulation thickness say from 1cm to 8 cm. from this, the corresponding thickness, with minimum total cost is considered as economical thickness. Therefore heat losses, cost of heat lost insulation cost, total cost for. Each cm of insulation thickness must be found out compared and economical thickness is determined.
ECONOMICAL THICKNESS FOR 3 INCH PIPE
SLNO INSULATION THICKNESS (m) HEAT LOSS (w) COST OF HEAT LOSS (Rs) INSULATION COST (Rs) TOTAL COST (Rs)
1 0.01 11200 3384 450 3834
2 0.02 11300 3415 510 3925
3 0.03 11600 3505 570 4075
4 0.04 11900 3596 630 4226
5 0.05 9957 3009 700 3709
From the above table we find that the economical thickness of insulation for 3 inch pipe is 0.05 or 5 cm.
ECONOMICAL THICKNESS FOR 2 INCH PIPE
SLNO INSULATION THICKNESS (m) HEAT LOSS (w) COST OF HEAT LOSS (Rs) INSULATION COST (Rs) TOTAL COST (Rs)
1 0.01 4920 3173 350 3523
2 0.02 4810 3115 410 3525
3 0.03 4500 2919 520 3439
4 0.04 4100 2650 600 3250
5 0.05 ¦ 3950 2361 690 3251
In the same manner for 2 inch pipe the economical thickness of insulation is 0.04m or 4 cm.
HEAT LOSS CALCULATION FOR NEW MATERIAL (PERLITE)
The heat loss of steam main line coming from boiler is calculated as follows. The data's are
Operating temp (Top) = 214°c
Ambient T(amb) = 32°c
Outer radius (rl) = 0.095m
Inner radius ® = 0.04m
Length (L) = 150m
Thermal conductivity (K) = 0.063 w/mk
hin = 15.36w/m2k
hout = 5 w/m2k
Q5 = (Top-Tamb ()/ (((l/27irL)hin) +(ln(rl/r)/27tLk)+(l/(27trl2L)hout))
=((214-32)/(((l/27tx0.04xl50)xl5.36)+(ln(0.095/0.040)/2Tcxl50x(0.063/1000)+(l/(27tx0.0952xl50)5}i
= (182)/(2.33+14.48+3.526)
= 8.94kw
2. 18.5kg/m3 steam main line J3001
Operating temp (Top) = 214°c
Ambient temp (Tamb) = 32°
Outer radius (rl) = 0.07m
Inner radius ® = 0.03m
Length (L) = 20m
Thermal conductivity (K) = 0.063 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q 6 = ((Top -Tamb)/ (((l/2raL)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout))
= ((214-32)/(((l/27ix0.03x20)xl5.36)+(ln(0.07/0.03)/27ix20x(.063/1000)+(l/(27tx0.072x20)5))
= ((182)/(17.26+123.78+4.97)
= 1.24kw
3.18.5kg/m3 steam main line J4501/J5001
Operating temp Top Ambient (Tamb) Outer radius (rl) Inner radius ® Length (L)
Thermal conductivity (K)
hin
hout
214°c
32°c
0.07m
0.03m
70m
0.078 w/mk 15.36 w/m2k 5w/m2k
Q7 = ((T0p -Tamb)/ (((l/27trL)hin) +(ln(rl/r)/27iLk)+(l/(27trl2L)hout))
= ((214-32)/(((l/27ix0.03x70)xl5.36)+(ln(0.07/0.03)/27tx70x(0.063/1000)+(l/(27tx0.072x20)5)) = ((182)/(4.95+35.36+4.97)) = 4.1kw
4.18.5kg/m3 steam main line to j'4501
Operating temp (Top) = 214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.07m
Inner radius ® = 0.03m
Length (L) = 25m
Thermal conductivity (K) = 0.063 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q8 = ((Top -Tamp)/ (((l/27irL)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout))
=((214-32)/(((l/2;tx0.03x25)xl5.36)+(ln(0.07/0.03)/27ix25x(.063/1000)+(l/(27ix0.072x20)5))
= ((182)/(13.6+99.02+4.97))
= 1.57kw
COST OF HEAT SAVED USING PERLITE INSULATION SYSTEM
1.18.5kg steam main line
Cost of fuel Calorific value Boiler efficiency Mineral wool insulation
= RS23
= 20000kj/kgk
= 80%
18.5kg steam main line (Ql) 18.5kg steam main line j3001 (Q2) 18.5kg steam line to j45001/j5001(Q3) 18.5kg steam pipe line j4501(Q4) Perlite insulation
=10.6kw =1.48kw =4.73kw =1.81kw
18.5kg steam main line (Q5 )
8.94kw
18.5kg steam main line j3001(Q6) =1.24kw 18.5kg steam line to j45001/j5001(Q7) =4.01kw 18.5kg steam pipe line j4501(Q8) =1.57kw
Cost 1 =((Ql-Q5)/calorific value x boiler efficiency)x3600x24xcost of fuel =((10.6-8.94)/20000x0.8)x3600x24x23 =RS 206/day =RS 75190/year
Cost 2 =((Q2-Q6)/calorific value x boiler efficiency)x3600x24xcost of fuel =(( 1.48-1.24)/ 20000x0.8)x3600x24x23 =RS 34.75 =RS 12683.75/year
Cost 3 =((Q3-Q7)/calorific value x boiler efficiency)x3600x24xcost of fuel =((4.73-4.01)/ 20000x0.8)x3600x24x23 =RS 81.9/day =RS 29893.5/year
Cost 4 =((Q4-Q8)/calorific value x boiler efficiency)x3600x24xcost of fuel =((1.81-1.57)/ 20000x0.8)x3600x24x23 =RS 34.9/day =RS 12738.5/year
Total savings per day =206+34.75+81.9+34.9 =RS 357.55
Total savings per year =75190+12683.75+29893.5+12738.5. = RS 130505.75
COST OF PERLITE INSULATION
SL NO DESCRIPTION 3 INCH PIPE IN RS/M 2 INCH PIPE IN RS/M
1 Insulating material 450 375
2 Aluminum sheets 100 80
3 Screws 30 25
4 Labour and repairs 120 120
Total cost of insulation of perlite per m for 3 inch pipe = RS700 Total cost of insulation of perlite per m for 2 inch pipe = RS600
Cost of insulation for 18.5kg steam main line =700x150
=RS 105000
Cost of insulation for 18.5kg steam line J3001 =600x20
=RS 12000
Cost of insulation for 18.5 kg steam line J4501/J5001 =600x70
=RS 42000
Cost of insulation for 18.5 kg steam line to j 4501 = 25x600
=RS 15000
Total cost of insulation = 105000+12000+42000+15000
=RS 174000
PAYBACK CALCULATION
PAY BACK TIME =Total investment/savings per day = 174000/354 =491 days
= 16 months and 3 days
CONCLUSIONS
AND SUGGESTIONS
The cost effectiveness of the insulation system was done satisfactorily. As stated above due to replacement in the insulation system, heat losses and cost losses and cost of heat loss were reduced considerably. The estimated annual savings for the new insulation amounts to approximately Rsl30505/-. The pay back period was estimated to be 16 months and 3 days. The average life time of the protection system being 15 years after the pay back period the savings obtained for the rest of its life will be a great asset to the company.
As a result of continues damages caused by sagging, bulging, contraction, mechanical damages, powdering, the insulation system is replaced almost once in 15 years
COST EFFECTIVENESS OF MINERAL WOOL INSULATION Vs PERLITE INSULATION
PROJECT REPORT
Submitted by
DIPU.K.SHAJI GITHU BABU VARUN KUMAR. T.K VIMAL MENON
ABSTRACT
The main objective of this project is to make the cost effectiveness analysis of the system of the thermal insulation of the pipe lines in petrochemical plant which carries steam. In a chemical plant maintaining temperature of fluids in different pipe lines assume greatest importance as each process is performed at particular temperature.
The project work was carried out in Hindustan Organic chemicals located at Ambalamugal, Kochi, which is public limited company manufacturing Phenol, Acetone and Hydrogen peroxide.
Steam is produced in a high pressure boiler at the rate of 20 tones/hour. The hot steam is conveyed through thermal insulated pipes for services such as steam tracing, heating etc. Heat loss from the steam passing through pipes is prevented by wrapping the pipe with mineral wool. This existing arrangement was not found to be effective in preventing heat loss from pipes due to various reasons. We were therefore assigned the of designing an insulation system for particular steam line carrying with a suitable insulating material with economy and effectiveness both equally in view.
The first step of our project is to make a thorough study of the existing including the properties of the materials used and their shortcomings. Next step is to find out an alternative material which should have better properties and to revive the method of application of the same, aiming at heat conservation and ultimate economy in running. This calls for a detailed study of properties and behavior of a number of thermal insulating materials economically available at present and to the right and suitable one for our application. A detailed study of the providing insulation to pipes is to be carried out before final is made. Care has to be taken into account, so that the selected material is available without scarcity.
LIST OF TABLES
TABLE 1 INSULATION TYPES AND APPLICATIONS
TABLE 2 TYPES OF INSULATION MATEIAL USED
TABLE 3 THERMAL CONDUCTIVITY OF THE MATERIAL
TABLE 4 COST DETAILS FOR MINERAL WOOL
TABLE 5 THERMAL CONDUCTIVITY OF PERLITE
TABLE 6 COST DETAILS FOR PERLITE
TABLE 7 STEAM LINE DESCRIPTIONS
TABLE 8 OBSERVATIONS
TABLE 9 ECONOMICAL THICKNESS FOR 3 INCH PIPE
TABLE 10 ECONOMICAL THICKNESS FOR 2 INCH PIPE
TABLE 11 COMPARISON OF HEAT LOSS OF BOTH
SYSTEMS
TABLE 12 COST OF PERLITE INSULATION
LIST OF DIAGRAMS
FIG 1 PLANT LAYOUT
FIG 2 PIPING INSULATION WITH TRACING
FIG 3 PIPING WITH METAL PROOFING
FIG 4 PIPING VERTICAL EXPANSION JOINTS
FIG 5 STEAM LINE CIRCUIT
LIST OF GRAPHS
TEMPERATURE Vs HEAT LOSS
TEMPERATURE DIFFERENCE Vs HEAT TRANSFER
THICKNESS OF INSULATION Vs HEAT TRANSFER
AIR VELOCITY Vs PERCENTAGE INCREASE IN HEAT
LOSS
TEMPERATURE Vs THERMAL CONDUCTIVITY ECONOMICAL THICKNESS Vs TOTAL COST
NOMENCLATURE
Top = operating temperature in Deg c
Tamb = ambient temperature in Deg c
hin = heat transfer coefficient of pipe in watts/m2 k
hout = heat transfer coefficient of aluminium in watts/m2 k
Re = Reynolds number
Pr = Prandl number
Nu = nusselt number
L = length of pipe in m
r = outer radius in m
rl = inner radius in m
K = thermal conductivity in w/mk
Ql = heat transfer of first pipe with mineral wool insulation in kw
Q2 = heat transfer of second pipe with mineral wool insulation in kw
Q3 = heat transfer of third pipe with mineral wool insulation in kw
Q4 = heat transfer of fourth pipe with mineral wool insulation in kw
Q5 = heat transfer of first pipe with perlite insulation in kw
Q6 = heat transfer of second pipe with perlite insulation in kw
Q7 = heat transfer of third pipe with perlite insulation in kw
Q8 = heat transfer of fourth pipe with perlite insulation in kw
TABLE OF CONTENTS
CHAPTER TITLE PAGE
ABSTRACT LIST OF TABLE LIST OF FIGURE LIST OF GRAPH NOMENCLATURE
1 BRIEF PROFILE OF THE ORGANISATION 1
1.1 COCHIN UNIT 2
1.2 AWARDS 3
1.3 PLANT LAY OUT 4
2 INTRODUCTION 7
2.1 INSULATION AN OVERVIEW 8
2.2 SCOPE 9
2.3 DEFINITION 10
2.4 GENERAL REQUIRMENTS 11
3 LITERATURE REVIEW 13
3.1 TYPES OF THERMAL INSULATION 14
3.2 INSULATION TYPES AND APPLICATIOS 17
3.3 THERMAL INSULATION PROPERTIES 17
3.4 INSULATING MATERIALS 20
3.5 PIPING INSULATION DETAILS 23
3.6 PARAMETERS AFFECTING HEAT LOSSES 25
3.7 HEAT LOSS FROM THE BARE SURFACE 25
3.8 HEAT LOSS THROUGH INSULATION 27
3.9 HEAT LOSS FROM CYLINDRICAL SURFACES 30
4 COMPARITIVE STUDY 31
4.1 INTRODUCTION 32
4.2 MINERAL WOOL MATERIAL 33
4.3 PERLITE MATERIAL 36
5 SURVEY METHODOLOGY 40
5.1 INTRODUCTION 41
5.2 CIRCUIT DETAILS 42
5.3 OBSERVATIONS 46
6 CALCULATIONS 47
6.1 CALCULATION OF ENTHALPY 47
6.2 HEAT LOSS CALCULATIONS FO MINERAL WOOL 51
6.3 DETERMINATION OF ECONOMICAL THICKNESS 53
6.4 HEAT LOSS CALCULATION FOR PERLITE 56
6.5 COST OF HEAT SAVED USING PERLITE SYSTEM 59
6.6 COST OF PERLITE INSULATION SYSTEM 60
6.7 PAYBACK CALCULATIONS 61
7
CONCLUSIONS & SUGGESTIONS
62
CHAPTER -1
A BRIEF PROFILE OF THE ORGANIZATION
The organization was in-corporate with a view to Set Up manufacturing of chemical intermediates with the objectives of giving inputs to the development of downstream industrial units in sector like dyes and dye intermediates, drugs and pharmaceuticals, rubber chemicals, laminations, solvents etc. The first unit was set up at Rasayani in Maharashtra which commenced production in 1970. The second unit was started at Cochin in Kerala, which started production in 1987. In the year 1988 a subsidiary company viz Hindustan fluorocarbons Ltd. was commissioned at Hyderabad. The company is presently engaged in the manufacturing of a wide range of petrochemicals. The major products serve as import substitutes.
The organization is a public limited company, which is managed by a board of directors consisting of six members.
The management is assisted by a team of well qualified and experienced professionals in technical financial safety, marketing, legal and other key areas.
COCHIN UNIT
Commissioning of Cochin (phenol and acetone) in 1987 headed another path breaking step of HOC;s entry into the field of petrochemicals. The Cochin plant has an installed capacity of 24,000 TPA of acetone and 409000 TPA of phenol; both are highly versatile organic chemicals. The Cochin unit comprises of three states of plant, Viz.
1. Propylene recovery plant
2. Cumene plant
3. Phenol plant
Universal oil products inc (UOP', USA One of the] world leaders in the field of petrochemicals has supplied the technology for phenol-cumene plant. Detailed engineering for all the plants and also off-site work was done by FEDO and Engineers Indian Ltd. Provided engineering for the propylene plant and Effluent treatment plant.
The company has achieved the ISO 9002 certification for its quality measures in the production process and ISO 14,000 for environmental quality standards. The entire operation of plant is totally Automatic remote controlled. Continuous on-line monitoring of the process results in perfect quality control.
The organization has high tech safety features to minimize hazards. Most modem effluent treatment plant assures complete safety to the environment confirming to international specifications. Latest energy conservation and optimization concepts have been incorporated at the beginning stage. This is the first company to export Phenol and Acetone from India.
State pollution control board has awarded the company with the certificate of merit.for pollution control. Cochin plant was awarded with the best pollution control measures among chemical plants in the state of Kerala.
AWARDS
1) ISO 9002 from BVQI in the year 1994.
2) Best productivity awards in 1989-91,91-92,94-95 (by Kerala state productivity council).
3) Safety awards (by National safety council) 1989,90,91,93,94,95,96,97,98,99.
4) Pollution control measures 1988-89,95,96,97.
5) ISO 14000 in the year 1999 for Environmental continues production.
1. H2O2 plant
2. Main tankage
3. H2 plant 1
4. Compressor house
5. DM plant
6. Boiler
7. H2 Plant 2
8. North Tankage
9. Fractionation section
10. Hot oil plant
11. Tar cracking plant
12. Cumox plant
13. Cumene plant
14. South tankage
15. Cumene storage
16. Effluent treatment plant
17. Cumene storage
18. Main receiving station
19. Captive power plant
20. Main control room
21. Propylene plant
22. Propylene storage
23. LPG storage
24. Cooling tower
25. Administrative block
26. Pre-treatment plant
27. Water storage
28. Emergency escape road.
CHAPTER -II INTRODUCTION
INTRODUCTION
Heat is a form of energy, which is required to perform many activities. But like other forms of energy, heat energy also travels from one place to another. The transfer to heat differs from matter to matter. There are three ways in which heat can be transformed from one point to other.
1. Conduction
2. Convection
3. Radiation
Heat transfer from body to body contact
Heat transfer by actual movement of particles
Heat transfer without need of particles in the medium.
Electric power generation and steam production for diverse industrial application rely on the convention of potential energy in a fuel into useful work. It is estimated that only 40% of the total potential energy in the fuel is converted into useful work. Heat insulation materials make a major contribution towards this capture of this percentage of total potential energy.
INSULATION AN OVERVIEW
Thermal insulation is a material, which retards the flow of heat. It is used as a barrier between two bodies at different temperature either to reduce heat loss from hotter body or to prevent heat entry into a cooler body. As heat is energy, the study of thermal insulation is the study of "Conservation of energy". As energy has a monetary value insulation conserves money. Functions
1. Conserve energy
2. Control temperature
3. Control transfer of energy
4. Retard freezing
5. Control fire
Purpose
The purpose to use the heat insulation for plants is the prevention of at from useless radiation to save fuel, power and heat energy. To accomplish this purpose, 100% of adiabatic property of heat insulation should be displayed.
SCOPE
Insulation materials are usually composed of filaments generally circular in cross section or in the from of slabs. Generally the diameter of the insulation is greater than the outer diameter of the pipe and of length considerably greater than the diameter.
The insulation material may be of signal layered or of composite filaments. The materials used for manufacturing thermal insulation are usually fibrous, organic naturally occurring of manufactured.
The thermal insulations are generally installed in refinery equipment and piping vessels, equipments, heat exchangers, pipes and fittings, flues, ducts, tanks, valves, steam generator casing, fixture casing, steam turbines etc. operating between a particular temperature limit.
The flowing are the several purpose of thermal insulation
1. the maintenance of process temperatures.
2. The conservation of energy when a loss of heat is not desired.
3. The protection of personnel from heat.
4. Steam of electric heat tracing.
5. Noise attenuation.
DEFINITION
"Thermal insulation is used as shielding from excessive temperature and heat
losses".
"According to thermodynamics when two systems are brought into contact through some kind of wall, energy transfers, such as heat and work takes place between them" Here the heat transfer takes place by the ode of conduction.
Heat conduction is the mode of heat transfer accomplished via two Mechanisms.
1. By molecular interaction, where by the energy exchange takes place by kinetic motion or direct impact of molecules.
2. By drift of 'free' electrons as in the case of metallic solids.
Definitions of all the terms used are in accordance with then India Standard specifications.
GENERAL REQUIREMENTS 1. Needs
Thermal insulation shall be provided for all vessels, equipments, heat exchangers, pipers and fittings. Etc. containing fluids or vapours for which it is necessary to
a. Conserve heat
b. Maintain temperature for process control.
c. Provide for personnel protection.
2. Protection of materials during storage.
Insulation materials shall be protected against the weather at all times from delivery to finish cladding. Decking and covering with tarpaulins alone are not considered efficient protection from the weather. Insulation materials shall at no time be stacked directly on the ground.
3. Hydrostatic Testing
If the insulation work proceeds in advance of hydrostatic testing and inspection, welded and mechanical joints shall be left insinuated for a length of at least 300mm on either side. Such joints shall be insulated after the testing and inspection is over. The insulation of flanges shall not be done until pipelines and vessels have reached the operating temperature and the flanged joints have been proved to be light. After that the insulation can be applied.
4. Anti Corrosive paint
The surface to be insulated after being thoroughly cleaned and wire brushed a hall be given one coat of anti-corrosive paint applied by brush before the commencement of insulation application.
5. Insulation for personnel protection
Piping and equipment that are not insulated but have a surface temperature exceeding 50C shall be insulated for personnel protection when
i. The bottom of the pipe in 2 meters and less from the ground or permanent
working floor or platform or walkway.
ii. .The piping and equipment, or parts there of are within 600mm from a
platform, floor or walkway.
Piping and vessels, to be insulated if the temperature in the outermost surface in 50 C or more. Vessels or equipments in horizontal position, which are to be insulated for personnel protections, shall be fully insulated when the outside diameter is less than 1250 mm and to a height of 2 Meters form the floor working platform.
CHAPTER - III LITERATURE REVIEW
TYPES OF THERMAL INSULATIONS
There are various types of thermal insulations available. The selection of thermal insulation depends upon the
a. Equipment to be insulated
b. Purpose for which insulation in needed.
Some of the types of thermal insulation commonly used are:
1. Blanket Insulation
A flexible insulating material composed of felted fibrous material without binder, but reinforced with confining media .
2. Block Insulation
Straight or segmental blocks of board insulation with or without facing and with or without attachment for application puipose.
3. Calcium Silicate insulation
Insulation composes of hydrated calcium silicate with small quantity of material
fibers.
4. Composite Insulation
Multi layer insulation in which different layers have different properties and characteristics.
5. Fibrous Insulation
Insulation material composed of filaments generally circular in croos-section and of length considerably greater than the diameter.
6. Pipe Insulation
It many be block form, moulded form, flexible form, strip form or in forms.
a. Block Form : Segmental blocks of rigid thermal insulation materials un faced or
the exterior faced with a protective material. For applications are received.
b. Moulded (performed) Form: Rigid or flexible cylinder of thermal insulation
material, either not split or suitable split longitudinally, either enfaced or faced on
the exterior with a protective materials, for application as received and generally
furnished with fixing bands.
c. Flexible Form : Mat or blanket insulation supplied in exact width to fit round any
standard diameter pipe.
d. Strip Form: Mat or blanket insulation in the form of a strip between 75 to 150 mm
width for bandage - wise applications.
e. Rope Form : A loosely braided sleeve of asbestos, Glass yam on wire packed with
asbestos fibers or mineral wool
7. Multi- layer insulation
Insulation comprising more than one layer of insulating material.
8. Hot Face insulation
Insulating materials which may be exposed directly to hot gases or high temperature areas.
Apart from this, some other types of thermal insulation used
1. Backing insulation
2. Batt insulation
3. Board insulation
4. Cellular insulation
5. Flexible insulation
6. Loose fill insulation
7. Mat insulation
8. Powder insulation
9. Rigid insulation
10. Sprayed insulation
INSULATION TYPES AND APPLICATIONS
SI. No Type Application
1 Urethane foam Hot and cold pipes
2 Cellular glass blocks Tanks and pipes
3 Fiber-glass blankets Tanks and equipment
4 Fiber-glass preformed shapes Piping
5 Elastomeric sheets Tanks
6 Fiber-glass mats Pipe and pipe fittings
7 Elastomeric performed shape Pipe and fitting
8 Fiber glass with vapour barrier blanket Refrigeration lines
9 Fiber-glass boards Boilers, tanks, heat exchangers
10 Cellular glass blocks and boards Hot piping
11 Mineral fiber blankets Hot piping
12 Mineral wool blocks hot piping
13 Calcium silicate block, boards Hot piping boilers
14 Mineral fiber blocks Boilers and tanks
15 Mineral fiber preformed shapes Hot piping
THERMAL INSULATION PROPERTIES
There are certain properties, which should be taken into account during selection of insulating material during installation
1. Low Conductivity
The coefficient of thermal conductivity should be less for a good thermal insulation, so a s to prevent the loss of heat through the insulation.
2. Low water absorption
i. Once water is absorbed into the insulation even if its conductivity is extremely
low, the heat conductivity of the materials is increased and the diabolic effect is
extremely reduced so as to make the heat conductivity of the materials close to
that water 30.5 kcal/m.h.c
ii. Absorptions of water inside the insulation, causes the outer portion of the pipes to
get rusted.
3. Non-corrosive
The insulation materials should be free form chloride and other corrosive substances. Ordinary stainless steel pipes and equipments is very susceptible to stress corrosion cracking temperatures above 60c, which may occur due to chloride content present in the insulation
4. Resistance to thermal Stress
In upset conditions there is constant expansion and contraction activities contraction is the property generated from dehydrating the water of crystallization the resultant effects is camber and cracks at the temperature ranges from 200°C to 300°C when expansion is allowed to cool down and the parts contract and are resorted to the original state, thus the resorting property.
5. Fire Resistance
The thermal insulation should be fire resistant and should be non combustible. It is should have very low thermal diffusivity.
6. Acid & Alkali Resistance
The thermal insulation should be resistance to concentrated acid attacks such as Sulphuric acid hydrochloric acid & nitric acid.
7. Pollution free
The thermal insulation material should not pose any health hazards.
8. Consistent performance
The thermal insulation should retain its shape and thermal conductivity throughout its life and should not be affected by weather conditions.
9. Easy Insulations
The thermal insulations must be easily installed and should be easily removed for maintenance work
10. Strength.
The installed thermal insulation should be able to withstand human foot traffic and in-service thermal and mechanical vibrations.
INSULATING MATERIALS
The insulating materials and protective covering shall be new and fresh, incombustible rot-proof non-hygroscopic and shall be guaranteed to withstand continuously and without deterioration the maximum temperature to which they will be subjected under the specified applications. The insulating material and any combustion, with water or moisture to form substances which are more actively corrosive to the applied surface than water or moisture of form substance, which are more actively corrosive to the applied surface than water or moisture alone. The materials shall not offer substance to fungus or vermin and must not pose health hazard.
The insulation materials to be used for insulation of pipes, vessels, heat exchangers, equipments etc. Shall be mineral wool in the form of preformed pipe sections or mattresses subject to limitations of carbon steel surface operating in the temperatures ranges of 25 c - 700 c and stainless steel surface operating in temperature range of 25 c and 600 c.
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Piping insulation with electric heat Tracing
Insulating Cement
The insulating cement will have the same composition as that of main insulating materials to which it is applied. It shall be capable of withstanding the same t c.
Finishing Cement
The finishing cement, when used shall be made of inorganic fibers and Portland cement so that it will set to hard finish. The application density for finishing cement shall be 1050 kg/cu.m to 1100 kg/cu.m.
Sheeting Materials
The sheeting material for all insulated piping and equipment shall be aluminum / galvanized steel.
Binding And Lacing Wire
Binding or lacing wire should be made up of galvanized steel wire where interface temperature is 400 c or more, binding wire will be stainless steel wire.
Straps And Bands
All straps and bands shall be of galvanized steel. For securing aluminum material, stainless steel or anodized aluminum band shall be used.
Screws
It may be of self-tapping type and shall be of galvanized materials.
PIPING INSULATION DETAILS
External surfaces of the pipe to be insulated shall be cleaned by wire brushing to remove dirt and lose scales. If painting is required it is to be done before laying the insulation.
All pipes and supports shall be permanently set before insulation is started. Disturbed pipes and supports shall be restored to their original location and alignment when the insulation is complete.
Figure-"
Insulation is the form of preformed pipe sections shall be applied over the pipe without the use of spacer rings. When mineral wool mattresses are used they shall be wrapped around the pipes without any un4er layer. On top of each layer wire'-netting shall be applied and tightly butted against each other so that fibers interlock both along the longitudinal and circumferential joints.
At uninsulated flanges, pipes line insulation shall be stopped off at suitable distance from the flanges, so that flange bolts can be withdrawn without disturbing insulation
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Piping Vertical Expansion joints Metal Sheet Finish
All Pipes shall be covered by a specified sheating to the outside of insulation with 25 mm circumferential and longitudinal overlaps. The overlapping shall be grooved so as to prevent ingress of water into insulation. The sheating shall be secured to themselves by self tapping screws. Sheating joints need not nsecessarily occur at spacer rings.
PARAMETERS AFFECTING HEAT LOSSES
Heat is a form of energy, which flows from a body of higher temperature to a body of lower temperature. So whenever there comes a temperature difference heat flow takes place.
There are parameters which effects the rate of heat flow. They are:
1. HEAT LOSES FROM BARE SURFACES
The heat losses from bare surface at different temperature can be shown graphically.
Heat
loss
Graph 1: Temperature Vs heat Loss
The graph shows the relationship between heat loss taking place between bare surface and insulated surface.
The heat losses so obtained on graph are average for still air conditions. Variation of heat loss may take places between various pipe sizes and different absolute temperature of surroundings, but these variations are small compared with that caused at comparatively at low air velocities.
The graph also illustrate the necessity of providing insulation.
Effect of Air Velocity On Loss From Bare Surfaces
The rate of heat loss from a surface maintained at constant temperature is generally increased by air circulation. This is shown graphically
Heat transfer
Temp. Difference
Graph 2 : Temp Difference Vs Heat Transfer
Incase of well insulated surface increase in losses caused by air circulation ae small compared with increase in bare fittings
Heat losses bare fittings
Very often even when pipes are thoroughly insulated, flanges and fittings ae left bare because of belief that losses from the parts are not so large however it is estimated that pair of 10 inch standards flanges having an area of 343 fts would lose at 100-16 steam pressure 9ie.,) an amount equivalent to more than 1 ton coal / year.
2. HEAT LOSS THROUGH INSULATIONS
It was found that heat loss will take place even though if the surface are provided with an effective insulation. But the heat loss taking plae from such surface will be very negligible when compared to that of bare surfaces.
The rate at which heat loss takes place is more, less the heat loss and vice versa. This relationship can be demonstrated graphically.
Heat transfer
Temp of hot surface 1600 cl
Thickness of insulation
Graph 3: thickness Vs Heat Transfer
Additional savings by thicker insulation will not be large when temperature and value of heat demand the use of greater thickness. The curve shows the loss per degree per temperature difference. The total losses can be obtained by multiplying the value of curves by temperature difference.
Effect of air velocity on heat losses from insulated surfaces.
In the case, of well insulated surfaces, the heat losses due to air velocity are very small compared with the increase in bare pipes or surfaces. This is due to the fact that, the air flowing over the surface of insulation can increase only the rate of heat transfer from surface to air and cannot change the internal resistance to heat flow inherent in the insulation itself. The effect of an insulated surface will depend upon :
1. Internal resistance or resistance offered by the insulation materials
2. Surface resistance
3. Temperature of surroundings and hot surface.
The internal resistance of a material to heat flow depends upon the :
a) Thickness V
b) Thermal conductivity' k' For flat surfaces both these vary indirectly. Total heat transmitted H = UA(Th - Tc) Where,
U - Over all rate of heat transfer co-efficient
A - Area of surface
Th - Temperature of hot surface
T - Temperature of cold surface
When heat flows through solid material and than out into air, a resistance to heat flow is encountered at the surface separating the solid from air Less heat will flow if no resistance were offered at that point. This is called surface resistance. Surface resistance will be small when compared to internal resistance of materials in connection with efficient insulation.
Effort of thickness of insulation on rate of heat transfer
The heat loss also depends on insulation thickness. Both thickness and heat loss are inversely related (i.e.) the thickness of air insulation is therefore to cool the surface of insulation to a temperature than it would have under still air conditions, thereby increasing temperature drop through insulation.
Bare surface
Air velocity
Graph 4 : Air Velocity Vs Percentage increase in Heat loss.
In case of surface located out doors, the combined effect of wind and rain may bring the surface temperature practically down to air temperature. The effect of air circulation on losses through insulations are based on flow of air over the surface of insulation and applied to cases where insulation is tightly sealed.
3. HEAT LOSS FROM CYLINDRICAL SURFACES (PIPES)
In case of cylindrical surfaces increasing thickness supplies additional resistance through which heat must flow but at the same time increase the area of path through which heat may flow.
Heat transfer per unit area of inner surface will be greater for insulation on a curved surface than on flat surface and that the smaller the radius of curvature, the greater will be rate of heat transfer unit of inner surface area
The heat loss per hour per degree difference in temperature per square foot of outer surface of insulation on a pipe or other cylindrical surface is given by
U2
1
r21oge(r2/rl) + l//
Where
rl
External radius of pipe
Radius of outer surface of insulation
U
Rate of heat transfer per hour per temperature per sq ft of
outer surface of insulation
Ul
V21 rlxU2
The rate of heat transfer through two thick insulation on 1 inch pipe is more than twice as great as through the same thickness of 12 inch pipe
CHAPTER -4 COMPARATIVE STUDY
INTRODUCTION
In order to replace the existing thermal insulation material with a new material, a detailed study of comparison is very important. Thermal insulation is a material which retards the flow of heat
The existing thermal insulation material is bonded mineral wool materials It is made from rock slag or glass processed from a molten state into fibrous form and shall be bonded with a suitable binder This material is fibrous and is in the form of mattress.
The new material which is to be replaced is a perlite material. It consists of millions of vitrified cells and is available in the shape of blocks. There are several important features for the perlite material out of which low water absorption and resistance to corrosion is outstanding.
MINERAL WOOL MATERIAL Description
The bonded mineral wool material shall ha made from rock stag Or glass processed from a molten state into fibrous form and shall be bonded with a suitable binder. Bonded mineral wool can be used with a suitable facing material for a temperature range of -50°c to 700°c.
Composition
The fibrous form insulation material shall be ductile, tough and extremely fine with fibre diameter varying from 3 to 5 microns. There shall be no setting of the fibres over an extended period of use.
Density
The applied density of mineral wool shall be as given below Operating temperature from 25°c to 500°c.
1. Unbonded mineral wool
120k g/m3
2 Lightly resin boned
Mineral wool mattresses
and preformed pipe
sections.
150 kg/m
3
Operating temperatures from 501° c to 700"c.
Unbonded mineral wool
200/kg/m3
2
Lightly resin bonded mineral wool
Mattresses and performed pipe section
150k g/m3
The bulk density of the ending facing will be normally within the following ranges and may be suitable for use unto a particular hot face temperature as given below.
Group Bulk Density Maximum recommended hot face temperature
Group 1 12-50 Kg/m3 Upto 250°c
Group 2 50-80 Kg/m3 Upto 400°c
Group 3 80-120kg/m3 Upto 550°c
Group 4120-160 kg/m3 Upto 750°c
The thermal conductivity shall be furnished at mean test temperature ranging from 50'c to 400'c in steps at different applied densities.
The thermal conductivity or k-value of the material shall not exceed the values given below.
Mean temperature c Thermal conductivity w/M deg
Group 1 Group 2 Group 3 Group 4
50 0.49 0.43 0.43 0.43
100 0.69 0.52 0.52 0.52
150 0.95 0.64 0.62 0.62
200 - 0.78 0.73 0.68
250 - 0.93 0.84 0.80
300 - 1.10 0.95 0.90
The insulation material shall be chemically inert and shall be rot and vermin proof. The finished mineral wool mattresses or pipe section shall not contain more than 10 ppm of chlorides and shall be packed in polythene bags for shipment to worksite.
The mineral wool fibers, both lighted resin bonded and unbonded shall be made into mattresses by laying the fibers with machines so as to ensure uniform density and thickness of the mattresses. The mattresses shall then be machine stitched along with the backing of specified wire-netting. The mattresses shall retain their form under ordinary handling conditions.
Cost Details for Mineral Wool
S.No Description 3 inch pipe Rs/m 2 inch pipe
Rs/m
1 Insulating material 107.24 96.85
2 Aluminum sheet 106.06 76.45
3 Screws 2.65 2.65
4 Labour 114.05 114.05
PERLITE MATERIAL
Perlitemp is a high temperature insulation, precision molded into pipe and block shapes. Its principal ingredient - expanded perlite is one of best of all the known naturally occurring insulating materials. It's characteristics structure consists of millions of vitrified cells. Through a property process these particles are bonded together with special inorganic binders and reinforcing fibres, molded and baked. The final product has very:
a) Low thermal conductivity
b) Non-corrosive
c) Asbestos free
d) Moisture and fire resistant
e) Light in weight
f) Easy installation
Important Features
The following are the important features
a) Low conductivity
Of all insulating material available, perlitemp has one of lowest coefficient for the use in power generation and process industries.
b) Non-Corrosive
The high content of sodium ions acts as a corrosion inhibitor and offers an excellent protection against stress corrosion of stainless steel.
c) Low water absorption
Perlitemp repels moisture in a 24 hrs total immersion in water. It typically absorbs less than 5%.
d) Fire resistance
In direct contact with the flame, the outside surface of insulation vitrifies and acts as additional protection for the valuable piping equipment thus preventing any bum through.
e) Mechanical resistance
It maintains its mechanical integrity in most demanding conditions of use
f) Recoverable
In maintenance work, when insulation needs to be dismantled, this can be recovered which is not possible by mineral wool.,
Physical Properties
Density -215kg/cu-m
Flexural strength
- 330KN/m2 (min)
Compressive Strength
- 540KN/m2, 5% compression
Lineral shrinkage
- 0.85% after 24 hours at 650uc
Maximum Service temperature
- 650UC
Thermal Properties
Surface burning characteristic
1. Flame spread - 0
2. 2. Smoke developed - 0
Chemical Properties
¢ It contain no asbestos
¢ Resists acids and alkallies
Environmental Properties
¢ Does not cause any irritation in contact with skin
¢ Non- Carcinogenic material
Graph 5: Temp Vs Thermal Conductivity
CHAPTER - 5 SURVEY METHODOLOGY
INTRODUCTION
For computation of heat losses, economical thickness of insulating material and to decide on the quantity of the materials required, the following data's are required
1. Operating temperature
2. Surface temperature
3. Ambient a temperature
4. Existing thickness of insulation
5. Length of steam lines etc.
The following methodology are used in arriving the dimensions. Determination Of Temperature
The temperature that are to be determined are:
1. Operating temperature (temperature of'steam passing through pipe)
2. Surface or skin temperature (temperature with insulation)
3. Ambient temperature
These temperatures are determined by an instrument known as infra-red thermometer
This instrument uses infra-red rays for finding out the temperature the infra red rays are focused to the place where temperature is to be measured. When these rays and focused, the corresponding temperature will be displayed in LED display. By this,
temperature with and without insulation are taken for different steam lines. Out of values the average value is taken for the calculation purpose.
Determination Of Thickness
The thickness of insulation is measured by pushing the needle ofi the thickness measuring instrument into the material and then measuring the length of needle with a depth gauge.
The thickness measuring instrument consists of 3mm diameter, 200MM long mild steel rod pointed to a sharp conical end. The length of conical portion shall be 2cm. The rod is fitted with a metallic disc 75mrn diameter and 50g in weight which is provided with means of clamping it to the rod.
Push the thickness measuring instrument into the specimen + perpendicular to the plane of the material surface, until its point touches but does not penetrate the underlying surface. Lower the disc gently down the rod until it rests under its own weight at constant level on top of the material and is not pushed into the surface. Clamp the disc in this position and remove the measuringinstrument. Measure the exposed length of the rod to 0. 1 mm with a depth gauge.
CIRCUIT DETAILS
The steam produced from a high pressure boiler which then branches into several sections of different pressures according to the plant requirement The steam line so chosen is the main line coming from the boiler having a pressure of 18.5 kgcm" .
The main line again branches into several sections as shown in the figure The pressure so produced in boiler is 20kgcm2 . The steam coming from the boiler first passes through the flow meter where the pressure is reduced to 18..5 kgcm2. Steam after passing through flow meter is branched and is passed to evaporator. The other section then passes to wash water column ejector system (cumene plant). The remaining steam is then diverted into Hydrogenation ejector and Fractionation section. These sections are interconnected with pipes of different size, specifications etc.
The different working units are designated by codes. The following codes are specified are specified as follows
J3001 - Evaporator (Evaporation section vaccum system)
J2rJ01 - Wash water column ejector system (Cumene plant)
J5001 - Hydrogenation ejector
J4501 - Fractionation ejector
STEAM LINE CIRCUIT
5054-sh-25-lA2A,
4792-SH-50-A2A,
4
9004-SH-A2A,
45001 9003-SH-80-A2A!
44501
2118-SH-40-A2Ai
H3001
1. Boiler
2. Evaporator
3. Wash water column ejector system
4. Hydro generation ejectors
5. Fractionation ejector
J2001
OBSERVATIONS
The table shows that the observation made for the existing thermal insulation (LB mineral wool) in the steam line circuit.
Sl.No. Description OD L ETI MATL OPT AMB.T SURFACE Temp
1 18.5 kg steam main line 88.9 150 50 LB 214 32.3 53.1
2 18.5 kg
steam
J3001 60.3 20 50 LB 214 32.3 50.8
3 18.5 kg line to J4501/5001 60.3 70 50 LB . 214 32.3 47.1
4 18.5 kg line to J4501 60.3 25 50 LB 214 32.3 47.8
Legend:
OD = Outer dia in mm
L = Length in mm
ETI = Existing thickness of insulation in mm
OP.T = Operating temp in deg C
AMB.T = Ambient temp in deg. C
SURFACE TEMP = Surface temperature in deg C
INTRODUCTION
The main objective of the design is the replacement of existing thermal insulation with a new product. It was found that, the existing thermal insulation is less economical, due to the following reasons.
1. High heat loss
2. High water absorption
3. High maintenance cost
4. Less durable
5. High thermal conductivity
It was found that the new material is sufficient enough to overcome the existing thermal insulation. A detailed study of new product was conducted and found to be more effective than the existing one.
The design process involves
1. Heat loss analysis
2. Determination of economical thickness 3 Savings and Payback
HEAT LOSS ANALYSIS
Whenever there is a temperature difference between the surfaces and surroundings, heat loss takes place. Even though, thermal insulation is provided, small amount of heat transfer will take place. The rate of heat transfer will depend on
a) Internal resistance by insulation
b) Surface resistance
c) Temperature if hot surface and surrounds
Oc
Let us consider a layer of insulation which might be installed around a circular pipe as shown in figure. Inner temperature of insulation is fixed at 9h, outer surface is exposed to a convection environment at 9c.
The rate of heat loss taking place through single layered insulation is given as
below
Q ((Top - Tamb)/ (((l/27irL)hin) +(ln(rl/r)/2rtLk)+(l/(27irl2L)hout))
Where,
Q - Heat loss through insulation in w/m.
T01, - Operating temperature of the steam line in °C Tamb - Ambient temperature in °C r - Outer diameter of pipe in cm
rl Outer diameter of layer of insulation in contact with pipe in cm
K Thermal conductivity of insulation (w/mK)
CALCULATIONS
CALCULATION OF HEAT TRANSFER COEFFICIENT
Reynolds number = Re
M =18.5kg/hr
D = 0.08 m
(1) Re=4m(nrcd)
Re = 4xl8.5/(1.5xl0"5x7tx0.08x3600) =5455
The flow is turbulent
(2) Re = 5455
Pr = 1.43
Nu = 0.023xRe° 75xPr°33 = 0.023x5455° 75xl.43°33 = 22.31
(3) d = 0.08 m K =36xl0"3
hin = Nuxk/(d) = 22.31x36xl03/0.08 = 11.36 w/m2k
At d =0.06 m
hin = 15.3w/m2k
HEAT LOSS CALCULATION FOR EXISTING INSULATION (BONDED MINERAL WOOL)
1.18.5kg/ m3 steam main line
The heat loss of steam main line coming from boiler is calculated as follows. The data's are
Working temp (Top) = 214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.098m
Inner radius ® = 0.04m
Length (L) =150m
Thermal conductivity (K ) = 0.078 kw/mk
hin = 15.36 w/m2k
hout - 5 w/m2k
Ql = (Top-Tamb ()/ (((l/2;trL)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout))
=((214-32)/(((l/27rx0.04xl50)xl5.36)+(ln(0.095/0.040)/27txl50x(0.078/1000)+(l/(27ix0.0952xl50)5)) =(182)/(2.33+l 1.6+3.526) = 10.46kw
2.18.5kg/m3 steam main line J3001
Operating temp (Top) =214°c
Ambient temp (Tamb) = 32°
Outer radius (rl) = 0.08m
Inner radius ® = 0.03m
Length (L) = 20m
Thermal conductivity (K) = 0.078 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q 2 - ((Top-Tamb)/ (((l/27irL)hin) +(ln(rl/r)/27tLk)+(l/(27irl2L)hout))
=((214-32)/(((l/27ix0.04x20)xl5.36)+(ln(0.08/0.003)/27ix20x(.078/1000)+(l/(27tx.082x20)5))
= ((182)/(17.26+99.98+4.97)
= 1.48kw
3.18.5kg/m3 steam main line J4501/J5001
Operating temp (T0p) =214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.095m
Inner radius ® = 0.03m
Length (L) = 70m
Thermal conductivity (K) = 0.078 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q 3 = ((Top-Tamb)/ (((l/2;irL)hin) +(hi(rl/r)/27iLk)+(l/(27irl2L)hout))
=((214-32)/(((l/2Ttx0.03x70)xl5.36)+(ln(0.08/0.003)/2Tix70x(0.078/1000)+(l/(27tx0.082x20)5))
= ((182)/((4.93+28.56+4.97))
= 4.73kw
4.18.5kg/m3 steam main line to J4501
Operating temp (Top) =214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.095m
Inner radius ® = 0.03m
Length (L) = 25m
Thermal conductivity (K) = 0.078 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q4 = ((T0p-Tamb)/ (((l/2ra:L)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout)) =((214-32)/(((l/27ix0.03x25)xl5.36)+(ln(0.08/0.03)/27ix25x(.078/1000)+(l/(27tx0.082x20)5)) = ((182)/(13.6+81.6+4.97)) = 1.8 lkw
DETERMINATION OF ECONOMICAL THICKNESS
The required thickness of insulation for any specific application will depend upon the characteristics of insulating material and the purpose of the equipment.
When the sole object is to achieve the minimum total cost, the appropriate thickness is known as economic thickness.
The cost to be considered all the cost of heat losses from insulated surfaces during the chosen evaluation period cost of insulation system during the same period. Any increase in the amount of insulation applied will raise the cost of insulation which will decrease the cost of heat lost.
The sum of these two costs can be shown to lie on g curve with a rather flat region on either side of minimum value representing the economical thickness.
An economic study to determine justified thickness should consider following factors:
1) Hours of operation per year.
2) Fuel cost including labour and maintenance. Efficiency of combustion.
4) Pipe diameter.
5) Operating temperature and ambient temperature.
6) Estimated cost of installed insulation at actual plant site.
7) Amortization period.
8) Heat losses.
In order to determine economical thickness of a particular steam line, 'the following data's are required such as:
1) Heat losses.
2) Cause of heat loss.
3) Total cost compressing of cost of beat lost and insulation cost.
Whenever there will be an increase or decrease in thickness, there will be change in beat losses, cost of heat etc. So in order to judge economical thickness, the total including all coast are to be determined for a range of insulation thickness say from 1cm to 8 cm. from this, the corresponding thickness, with minimum total cost is considered as economical thickness. Therefore heat losses, cost of heat lost insulation cost, total cost for. Each cm of insulation thickness must be found out compared and economical thickness is determined.
ECONOMICAL THICKNESS FOR 3 INCH PIPE
SLNO INSULATION THICKNESS (m) HEAT LOSS (w) COST OF HEAT LOSS (Rs) INSULATION COST (Rs) TOTAL COST (Rs)
1 0.01 11200 3384 450 3834
2 0.02 11300 3415 510 3925
3 0.03 11600 3505 570 4075
4 0.04 11900 3596 630 4226
5 0.05 9957 3009 700 3709
From the above table we find that the economical thickness of insulation for 3 inch pipe is 0.05 or 5 cm.
ECONOMICAL THICKNESS FOR 2 INCH PIPE
SLNO INSULATION THICKNESS (m) HEAT LOSS (w) COST OF HEAT LOSS (Rs) INSULATION COST (Rs) TOTAL COST (Rs)
1 0.01 4920 3173 350 3523
2 0.02 4810 3115 410 3525
3 0.03 4500 2919 520 3439
4 0.04 4100 2650 600 3250
5 0.05 ¦ 3950 2361 690 3251
In the same manner for 2 inch pipe the economical thickness of insulation is 0.04m or 4 cm.
HEAT LOSS CALCULATION FOR NEW MATERIAL (PERLITE)
The heat loss of steam main line coming from boiler is calculated as follows. The data's are
Operating temp (Top) = 214°c
Ambient T(amb) = 32°c
Outer radius (rl) = 0.095m
Inner radius ® = 0.04m
Length (L) = 150m
Thermal conductivity (K) = 0.063 w/mk
hin = 15.36w/m2k
hout = 5 w/m2k
Q5 = (Top-Tamb ()/ (((l/27irL)hin) +(ln(rl/r)/27tLk)+(l/(27trl2L)hout))
=((214-32)/(((l/27tx0.04xl50)xl5.36)+(ln(0.095/0.040)/2Tcxl50x(0.063/1000)+(l/(27tx0.0952xl50)5}i
= (182)/(2.33+14.48+3.526)
= 8.94kw
2. 18.5kg/m3 steam main line J3001
Operating temp (Top) = 214°c
Ambient temp (Tamb) = 32°
Outer radius (rl) = 0.07m
Inner radius ® = 0.03m
Length (L) = 20m
Thermal conductivity (K) = 0.063 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q 6 = ((Top -Tamb)/ (((l/2raL)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout))
= ((214-32)/(((l/27ix0.03x20)xl5.36)+(ln(0.07/0.03)/27ix20x(.063/1000)+(l/(27tx0.072x20)5))
= ((182)/(17.26+123.78+4.97)
= 1.24kw
3.18.5kg/m3 steam main line J4501/J5001
Operating temp Top Ambient (Tamb) Outer radius (rl) Inner radius ® Length (L)
Thermal conductivity (K)
hin
hout
214°c
32°c
0.07m
0.03m
70m
0.078 w/mk 15.36 w/m2k 5w/m2k
Q7 = ((T0p -Tamb)/ (((l/27trL)hin) +(ln(rl/r)/27iLk)+(l/(27trl2L)hout))
= ((214-32)/(((l/27ix0.03x70)xl5.36)+(ln(0.07/0.03)/27tx70x(0.063/1000)+(l/(27tx0.072x20)5)) = ((182)/(4.95+35.36+4.97)) = 4.1kw
4.18.5kg/m3 steam main line to j'4501
Operating temp (Top) = 214°c
Ambient temp (Tamb) = 32°c
Outer radius (rl) = 0.07m
Inner radius ® = 0.03m
Length (L) = 25m
Thermal conductivity (K) = 0.063 w/mk
hin = 15.36 w/m2k
hout = 5 w/m2k
Q8 = ((Top -Tamp)/ (((l/27irL)hin) +(ln(rl/r)/27iLk)+(l/(27irl2L)hout))
=((214-32)/(((l/2;tx0.03x25)xl5.36)+(ln(0.07/0.03)/27ix25x(.063/1000)+(l/(27ix0.072x20)5))
= ((182)/(13.6+99.02+4.97))
= 1.57kw
COST OF HEAT SAVED USING PERLITE INSULATION SYSTEM
1.18.5kg steam main line
Cost of fuel Calorific value Boiler efficiency Mineral wool insulation
= RS23
= 20000kj/kgk
= 80%
18.5kg steam main line (Ql) 18.5kg steam main line j3001 (Q2) 18.5kg steam line to j45001/j5001(Q3) 18.5kg steam pipe line j4501(Q4) Perlite insulation
=10.6kw =1.48kw =4.73kw =1.81kw
18.5kg steam main line (Q5 )
8.94kw
18.5kg steam main line j3001(Q6) =1.24kw 18.5kg steam line to j45001/j5001(Q7) =4.01kw 18.5kg steam pipe line j4501(Q8) =1.57kw
Cost 1 =((Ql-Q5)/calorific value x boiler efficiency)x3600x24xcost of fuel =((10.6-8.94)/20000x0.8)x3600x24x23 =RS 206/day =RS 75190/year
Cost 2 =((Q2-Q6)/calorific value x boiler efficiency)x3600x24xcost of fuel =(( 1.48-1.24)/ 20000x0.8)x3600x24x23 =RS 34.75 =RS 12683.75/year
Cost 3 =((Q3-Q7)/calorific value x boiler efficiency)x3600x24xcost of fuel =((4.73-4.01)/ 20000x0.8)x3600x24x23 =RS 81.9/day =RS 29893.5/year
Cost 4 =((Q4-Q8)/calorific value x boiler efficiency)x3600x24xcost of fuel =((1.81-1.57)/ 20000x0.8)x3600x24x23 =RS 34.9/day =RS 12738.5/year
Total savings per day =206+34.75+81.9+34.9 =RS 357.55
Total savings per year =75190+12683.75+29893.5+12738.5. = RS 130505.75
COST OF PERLITE INSULATION
SL NO DESCRIPTION 3 INCH PIPE IN RS/M 2 INCH PIPE IN RS/M
1 Insulating material 450 375
2 Aluminum sheets 100 80
3 Screws 30 25
4 Labour and repairs 120 120
Total cost of insulation of perlite per m for 3 inch pipe = RS700 Total cost of insulation of perlite per m for 2 inch pipe = RS600
Cost of insulation for 18.5kg steam main line =700x150
=RS 105000
Cost of insulation for 18.5kg steam line J3001 =600x20
=RS 12000
Cost of insulation for 18.5 kg steam line J4501/J5001 =600x70
=RS 42000
Cost of insulation for 18.5 kg steam line to j 4501 = 25x600
=RS 15000
Total cost of insulation = 105000+12000+42000+15000
=RS 174000
PAYBACK CALCULATION
PAY BACK TIME =Total investment/savings per day = 174000/354 =491 days
= 16 months and 3 days
CONCLUSIONS
AND SUGGESTIONS
The cost effectiveness of the insulation system was done satisfactorily. As stated above due to replacement in the insulation system, heat losses and cost losses and cost of heat loss were reduced considerably. The estimated annual savings for the new insulation amounts to approximately Rsl30505/-. The pay back period was estimated to be 16 months and 3 days. The average life time of the protection system being 15 years after the pay back period the savings obtained for the rest of its life will be a great asset to the company.
As a result of continues damages caused by sagging, bulging, contraction, mechanical damages, powdering, the insulation system is replaced almost once in 15 years