Details Of Design Phase Iv

MUNDRA THERMAL POWER PROJECT Ph-IV(3 X 660 MW) ADANI POWER LIMITED, MUNDRA, GUJRAT

275 M HIGH R.C.C TRIPPLE FLUE CHIMNEY

DESISN BASIS REPORT FOR R.C.C TRIPPLE FLUE CHIMNEY DOC NO. : K8R04-SPC-S-03

CONTRACTOR SIMPLEX INFRASTRUCTURES LIMITED,KOLKATA

CONSULATANT DEVELOPMENT CONSULTANTS PRIVATE LIMITED 24 PARK STREET, KOLKATA-700016, INDIA

SEPT,2008

275 M HIGH TRIPPLE STEEL FLUE R.C.C STACK ADANI POWER LIMITED (3 X 660 MW POWER PLANT AT MUNDRA) DESIGN BASIS REPORT A.

SYSTEM DESCRIPTION

1.

General The 275 M (above finished ground level FGL) high chimney consists of a reinforced concrete shell as windshield above foundation raft with three 7.0 m internal diameter top hung steel flue inside, supported on insulating bearing blocks. The flues are supported laterally at a number of restraint floors. The flues are insulated by mineral wool insulation. Center line elevation of the steel ducts connecting the steel flues inside the Chimney is at EL.16.0 M. The finished grade level (FGL) of the Chimney will be at EL (+/-) 0.0 M which will be 9.2 M above MSL. The Chimney roof slab at EL.270.725 will be of reinforced concrete treated for water proofing and protected by a layer of acid resistant tiles laid in acid resistant mortar.

2.

Wind shield The outside diameter of the concrete shell at the top is 21.2 M and the outer diameter of the shell at top of raft will be 32.0m. Diameter and thickness of the shell varies along its height to suit the design requirements. The concrete for the shell will be of grade M 30. Openings in the shell have been provided for ventilation as required in the specification.

3.

Foundation The foundation for the chimney will consist of a reinforced concrete annular raft resting at 6.5 M below the existing ground level (7.3 M below the FGL) and supported on rock (Stratum-IV). The existing ground level at the chimney site is about 8.4 m above MSL. Under all loading conditions, the maximum permissible net allowable bearing capacity of the rock below the raft is taken as 75 t/sqm, which agrees with the “Report on Geotechnical Investigation Work” of this project. The concrete for the annular raft will be of M25 grade. The lean concrete base below the raft (mud mat) will be 75 mm thick concrete of grade M10.

4.

Flue All the three Steel flues will have 7.0 M internal diameter fabricated from 8 mm thick mild steel plates. Mineral wool insulation will be used for the entire length. 15371533.doc

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Insulation for the exposed portion (i.e. above roof level) will be clad with (0.5mm thk.) stainless steel sheet. Stainless steel cap of 8mm. thickness will be provided at the top of insulation. The steel flues will be top hung and supported from the floor at EL(+)261.625m. Arrangement will be provided for measuring concentration of particulate matters, NOx and SOx in the flue gas for monitoring and taking necessary measure for pollution control. The net suction available and the exit velocity of the flue gas for the conditions specified will be as under: BMCR(wet) BMCR(dry) Flue gas inlet temp (oC)

135

Inlet gas volume (Nm3/hr at 0oC and 746mm Hg of barometric pressure) Diameter of Flue at exit (M) Exit Velocity (M/Sec.)

135

2497381 2186305 7.0 7.0 27.750

Net draft (mm W)

42.853

24.29 32.386

When the gases are processed in a future FGD/GGH unit the gas temperature assumed is 92oC. The exit velocity at the lowered temperature will be about 21.75 M/Sec and the net draft available will be about 22.28 mm W. 5.

Insulation The exterior surfaces of all steel flues and ductwork from the underside of the roof to the interface flange will be insulated with insulation material of approved glass/mineral wool fibre of density 0.36kN/m3. The thickness of the insulation will be 100 mm thick (2 x 50 mm thick) for the entire flue. The insulation shall conform to IS: 8183. The insulation thickness shall be determined based on the maximum ambient temperature, surface air velocity worked out based on the draught of ventilation air in the annular space between the flue liner and chimney shell, insulation surface emissivity of 0.3. The exterior surfaces of all steel flues above the level of the roof shall also be

insulated with insulation material of approved rigid board of glass fibre with a maximum density of 0.48kN/m3, installed in double layers to provide a total minimum thickness of 100mm, and clad with galvanized steel material 0.5mm thick. Stainless steel cap of 8mm. thickness will be provided at the top of insulation of flue duct. The Temperature of the annulus has been computed using the air entry and exit openings as provided for 2 or 3 flues working simultaneously and for ambient 15371533.doc

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temperatures of 40 oC and 50 oC. The annulus Temperatures are given in the table below: Ambient Temp Temperature of Annular Space oC

2-Flues Working 40oC 50oC

3-Flues Working 40oC 50oC

45.59

47.45

55.37

57.07

It will not be possible to restrict the annulus temperature within 50oC when the external ambient temperature is also 50oC. 6.

Load Bearing Insulation Block (LBIB) 6 nos. of Load Bearing Insulation Block each of capacity 100 MT shall be provided for each flue as per Specialist Vendor’s design.

7.

Restraint Block 12 nos.(3 at each level) of lateral restraint blocks at 4 levels shall be provided for each flue as per Specialist Vendor’s design.

8.

Platforms There will be no external platforms. Aviation warning lighting fixtures will be mounted on sliding supports and shall project through openings in the windshield, so that they are accessible from interior platforms for maintenance purpose. All interior platforms i.e access platform and restraint floor shall be galvanized steel grating as specified in Indian Standards supported on steel framing. Platforms shall be capable of supporting a uniformly distributed live load of 5000 N/m2. The structural members of the platforms shall be supported on the concrete shell. There are 10 internal platforms other than the roof and are approximately at every 30m interval, arranged such that the stair arrangement is uniform. The platforms are at EL25.0, 40.95, 54.60, 84.175, 113.75, 143.325, 172.90, 202.475, 232.05 and 270.725. These platforms will not be monolithic with the RCC windshield and will be supported on steel beams, which would span between simple supports on the shell. The platform supporting structures shall be painted appropriately for protection. There will be steel tubular handrails in accordance with Indian standards, with kick plates at platform edges where required for safety. Openings for elevator shall be surrounded by handrail.

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9. Expansion Compensator One expansion compensator for each of the flues will be provided having the following specification:a) b) c)

Design temperature = 250o C Design Pressure = +/- 2000mm WC Fabric Layer Combination i) One layer of Stainless Steel Wire Mesh Size (16 x 16) ii) One layer of PTFE coated and both sides Laminated Glass Fabric of 0.95 mm thick and weight of 1225gms/m2. iii) One layer of 0.2 PTFE foil of 0.2mm thick and weight 460gms/m2 iv) One layer of Needled Glass felt of 9 mm thick and weight of 1500gms/m2 v) One layer of Woven Texturised glass fabric of 1.6mm thick and weight of 1310gms/m2.

10. Roll-up Door A 3000 wide x 4000 high chain operated rolling shutter at the ground level shall be provided for truck entry within the 7500 wide x 10000 high opening provided for the erection of flue cans. 11. Personnel Access Door(Man door) A steel door of size 1000 mm x 2100 mm high has been considered to provide personnel access to the chimney at the grade level. 12. Access Stair A full height staircase with intermediate landing platforms has been provided inside the shell. 13. Elevator A rack & pinion elevator will be provided inside the windshield to access all internal platforms. The brief specification of the rack and pinion elevator is: 13.1

Carrying capacity

:

400kg

13.2

Operational speed at 50Hz

:

(approx.) 40 m/min.

13.3

Cab floor size (inside)

:

1000 mm x 1100 mm

13.4

Landing Levels (including ground)

:

Same as the number of interior platforms

13.5

Electrical power supply system

:

415V, 3 Phase, 50 Hz.

13.6

Type of loading

:

Passenger

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13.7

Motors

:

One

13.8

Automatic stop equipment shall be provided in the elevator cab.

13.9

All necessary safety, equipment and devices should be installed as per international standards.

13.10

Phase failure relay shall be provided for the protection of the electrical equipment in the elevator system.

14. Electrical Works The chimney electrical works will include aviation warning lighting system, internal illumination system, lightning protection system and grounding system. 15. Painting Apart from aviation warning light the entire external surface of the wind shield will be painted in 11 alternate bands of red and white colour starting and finishing with red and in line with Table 6-1 of “International Standards and Recommended Practices for Aerodromes: Annex 14 ;Volume 1” published by International Civil Aviation Organization. The top 25 m of the paint will have acid and heat resisting properties and the rest will be of cementitious paints. Two coats of acid and heat resistant black bitumen paint shall be applied on inside surface of windshield for full height. 16. Concrete M-25 concrete will be used for foundation and M-30 concrete will be used for R.C.C shell and roof slab. 17.

Reinforcement All reinforcement will be of Grade Fe-500 steel conforming to IS:1786.

18.

Structural Steel Structural Steel will conform to Grade-A of IS-2062 for rolled steel members or plates up to 20 mm thickness. For plates above 20 mm thickness and welded construction steel conforming to Grade-B of IS-2062 shall be used. Shop connections will be all welded and field connections will generally be bolted unless specified otherwise.

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B. 1.

STANDARDS FOR STRUCTURAL DESIGN AND DESIGN PARAMETERS Codes of Practice : The following codes have been used in the structural design

a) IS : 456 – 2000

:

- Codes of Practice for Plain and Reinforced Concrete

b) IS : 4998 (Part I)-1975 - Design Criteria for Reinforced Concrete Chimneys c) IS : 4998 (Part 1)-1992 - Criteria for Design of Reinforced Concrete Chimneys Assessment of Loads (2nd Revision) d) IS : 4998

- Criteria for Design of Reinforced Concrete Chimneys

(Part-2, Section-1)-1998 Part-2 : Design Criteria, Section-1 : Working Stress Material (Draft) e) IS : 875 (Part 3)- 1987 - Code of Practice for Wind Loads f) IS : 1893 – 2002

- Criteria for Earthquake Resistant Design of Structures (Part – 1)

g) IS : 800 – 1984 2.

- Use of Structural Steel in General Building Construction

Design Parameters

a) Wind Load : Ref : IS : 875 (Part 3) – 1987 and IS : 4998 (Part 1) – 1992 Basic wind speed, Vb = 50 m/sec Terrain category

= 1

Class of Structures = C k1 = 1.08 k2 = As per Tables 33 of IS:875 (part 3) – 1987 (k2=0.78 at 10m ht to k2=1.085 at 275m ht.) k3 = 1.0 b) Seismic condition: Response Spectrum Method as per IS : 1893 – 2002 Seismic Zone 15371533.doc

= Page 6 of 10

V

Importance Factor Damping coefficient

= =

Response Reduction factor = Soil type = Peak Ground Acceleration (Zone Factor=0.36) =

1.5 5% 3.0 Type-I Hard 0.36g

c) Temperature : Temperature difference across the shell will be computed as per IS: 4998 (Part I– 1975 assuming all the three flues in operation. d) Live load

:

On roof = 3.0 kN/sqm. On internal platforms = 5.0 kN/sqm. On stairs = 4.0 kN/sqm. e) Reinforced Concrete Design : i) Foundation: As per IS : 456 – 2000, by Limit State Method. The thickness of raft will be as per Structural design requirements. ii) Shell :

The permissible concrete and steel stresses in the shell has been as per IS : 4998 (Part 1) – 1975.

Static modulus of elasticity of concrete has been as per IS : 456-2000. The maximum deflection at the top of chimney is not more than H/500, where H is the height of windshield above the top of raft. iii) Platform :

All internal platforms shall be made of structural steel .

f) Structural Steel Design : The design is as per IS : 800-1984. g) Bearing Capacity : The net allowable bearing capacity below raft at 6.5 m below FGL have been assumed as 75 t/m2 in design. C. TECHNICAL DATA SHEET All technical data are furnished below :

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Sl. No. 1

Items

Bidder' Data

Design Parameters a. Finished Floor Level inside stack b. Finished Grade Level (FGL) c. Founding Level of Raft d. Top Elevation of Stack flue e. Max. Temp. of Flue Gas at Stack Inlet

f. Inlet Flue Gas Volume (wet) through

EL(+) 0.150 m EL() 0.00 m (9.2m above MSL) 7.3 m below FGL (6.5 M below Existing Ground Level) EL(+) 275.0 m 135oC maximum 2497381

Stack-Nm3/hr g. Inlet Flue Gas Volume (dry) through Stack-Nm3/hr

2186305

h. i. j. k. l. m.

10oC 50oC 7.0 m 6.00 m x 12.0 m 16.0 m above FGL

Min. Ambient temp. Max. Ambient temp. Clear Internal Diameter of Steel Flues Inside Clear Size of Inlet Ducts Centre Line Elevation of Flue Inlet Duct Clear internal diameter of RCC shell at top n. Thickness of shell at top p. Thickness of shell at top of raft q. Grade of Concrete for i. Raft ii. RCC Shell 2

20.4 m 400 mm 750 mm M 25 M 30

Steel Flu The steel flues will be top hung[supported at the floor at EL(+)261.625m] and the internal diameter of the flue will be 7.0m and the entire length of the steel flue will be insulated with 100 mm thick mineral wool.

3

Vertical Loads a. Density of i. Concrete ii.

25

0.36 KN/m3 below roof, 0.48 KN/m3 above roof 18 KN/m3 78.50 KN/m3 78.50 KN/m3

Insulation

iii. Soil iv. Structural Steel v. Steel Flue

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KN/m3

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b.

4

5.0 3.0 4.0

Natural Frequency & Mode Shapes a. Computer Programme Used b. Natural Frequencies of Stack

c. d.

5

Live Load i. On internal Platforms ii. On roof iii. On Stairs

Number of Modes Considered Model For Analysis

Seismic Analysis a. Method of Analysis b. c. d. e. f.

Damping

h.

Value of

DCPL inhouse (0.33, 1.44, 4.32, 4.33, 9.75, 17.13, 20.25, 25.39, 32.29, 42.79)Hz, with and without flue will be performed and worst case will be used. 10 Lumped Mass Stick model using variable thickness conical elements (tapered diameter).

Response Spectrum Method as per IS 1893(Part 4) : 2005

Seismic Zone Zone Factor (Z) Response Reduction Factor ( R ) Soil Type Importance Factor (I)

g.

KN/m2 KN/m2 KN/m2

V 0.36 (very severe) 3 ( Table 9 ) Type-I Hard 1.5 5%

Sa

As per IS 1893 (Part I):2002

g 6

Wind Load Analysis a. Povision of Strakes at Top 1/3 rd Height b. Factors i. Basic wind speed , Vb

Provided 50 m/sec

ii. Risk Co-efficient k1

1.08 (for 50 years return period)

iii. Class of Structure for k2

C

iv. Terrain Category for k2 v. Hourly Mean Speed Factor , k2 (Table-33)

1 0.78 at 10m ht to 1.085 at 275m ht.

vi. Topography Factor k3

1.0

vii. Drag Co-efficient (CD) for external surface without Strakes

0.8 [for Reynolds No.(Re) = 2.14x107 to 4.75x107]

viii. Drag Co-efficient (CD) for external surface with Strakes

1.2 when strakes considered

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c. Along Wind Load Analysis i. Random Response Method

Dynamic Along Wind effects are evaluated using all horizontal modes from the first 10 modes. Davenport's Power Spectral density function is used to evaluate along wind responses of the modes and combined using individual peak factors.

d. Across Wind Load Analysis i.

7

Random Response Method

Dynamic Across Wind effects are determined using Rumman's method as adopted in CCIND code.

Design of RCC Shell & Accessories In the section design of RCC shell, loads and load combinations are taken as per specification. Allowable stresses in shell for various load combinations are considered as per IS: 4998 .For stress calculation modular ratio is 9.33 and coefficient of linear thermal expansion of concrete is considered as 1.2x10-5/oC

8

Opening Angle The opening sizes shall be restricted to have central angle less than 30o.

9

Deflection Along wind deflection allowable = < 546 mm

10

Foundation The foundation for the chimney will consist of a reinforced concrete circular / annular raft resting at 6.5 m below the existing ground level and supported on rock. Under all loading conditions, the net bearing capacity is assumed as 75 T/m2. No increase in bearing capacity have been considered. The concrete for the raft will be of M25 grade. The mud mat below the raft will be 75 mm thick, M 10 concrete.

11

Aerodynamic Study By Wind Tunnel To be informed Later

12

Factor of Safety Minimum Factor of Safety against Overturning for all conditions is considered as 2.0

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Other comments – 1. Hopper for collection /removal of ash at the bottom of flues to be considered. 2. Loading and location of duct supports inside and outside of the shell is required for design and provision for support pedestals over chimney raft., 3. Foundation design should be checked for no soil tension condition. 4. CI rain water pipe to be used.

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