This document summarizes the experience of indigenizing (domesticating) the waste heat boiler system at Vizag Steel Plant in India. Originally using Russian-made boilers, problems with erosion, corrosion, and maintenance were addressed. Tube bundles were replaced with Indian-made alloy steel tubes, reducing erosion. Bi-metallic corrosion at tube brackets was eliminated by specifying compatible materials. New single-shaft boilers were installed with larger dimensions to reduce gas velocity by 70%, preventing erosion. Refractory walls requiring frequent repair were replaced in future boilers. Through material selection, design changes, and replacing components, the Russian system was successfully adapted for local manufacturing and conditions.

1. 1

2. 2
Indigenisation of Russian Make
Waste Heat Boilers System
Our Experience
1. Salim G Purushothaman, AGM, Vizag Steel
2. B. Ravishankar, Manager, Vizag Steel
3. Jeevan Kumar, Assistant Manager, Vizag Steel

3. 3
Waste Heat
Heat Evolved from Dry Quenching of
Metallurgical Coke Produced In House
Quenching Medium – Circulating Nitrogen
Before Recovery - 800 Deg C
After Recovery - 160 Deg C
9 x 80,000 N Cu M/Hr
TOTAL Net HEAT AVAILABILITY = 124 G Cal/Hr

4. 4
Metallurgical Coke
Required for Smelting Iron Ore in Blast Furnace
Each Ton of Hot Metal Produced needs Half Ton Coke
We make Aprox 8500 Tons a Day

5. 5
COKE MAKING
Destructive Distillation of Low Ash Coal
- Heating Coal in the absence of Air to 1100 Deg C
Thus expelling all volatiles
To obtain Porous Carbon Concentrate, COKE
Made in Coke Ovens

6. 6
Coke Ovens
Coal Charged
Part of A Battery – Coke Ovens
Coking Time /Oven - 16 Hours
1 Battery – 67 Ovens
Batteries - 4
Rated Production– 100Pushings/Day/Battery
1 Oven – 32 Ton Coal to 25 Tons Coke

7. 7
Our Coke Oven Battery
Total Such Batteries in VSP – 4 Numbers

8. 8
Coke Produced
Collected In Buckets, 1 Pushout = 25Tons Coke
Temperature = 1000 to 1100 Deg C
Nature - Incandescent

9. 9
Need to Quench Coke
Coke to be Shipped to Blast Furnace
Shipment through Conveyors
Temperatures above 180Degrees Burns Conveyor
For Safety of Conveyor and Handling
Coke to be Quenched to 160 Deg C
Implication:
350 M Cal Heat /Ton Coke to be Removed

10. 10
Types of Quenching
Cooling Water
Coke Car
1.WET Quenching
All Heat – Lost
Pollution - Severe

11. 11
Types of Quenching
2. DRY Quenching
All Heat –Recovered
Pollution- Eliminated

12. 12
DRY vs WET (Quenching)

13. 13
CDCP Blocks of VSP

14. 14
RUSSIAN BOILERS OF CDCP
• Commissioned in 1986-87
• Make: Belgorod Power , Russia (Erstwhile USSR)
• Model : KCTK 39/440
• Type : Drum, Forced Circulation
• Rating : 39 Bar, 440 Deg C , 25.5 TPH MCR
• Gas Flow Rate : 80 000 N CuM/Hr
• Hot Gas Inlet : 800 Deg C
• Cooled Gas Outlet : 160 Deg C
• Construction : Twin Shaft , Refractory walled , Counter Flow Eco, & Evap

15. 15
RUSSIAN BOILERS OF CDCP

16. 16
SIDE VIEW
To Drum
From
Circulation Pump
Output
SH
Steam,
39 Bar

17. 17
RUSSIAN BOILERS OF CDCP

18. 18
Problems Faced
• Heavy Erosion – at Riser Tubes
-- at Evaporator side Bends
• Bi Metallic Corrosion – Bracket Area of Evap Top
Bundle
• 2 Days Cooling Time for shutdown inspections
• No access to inspect Sides of Bundles
• Frequent damages to Refractory lining due to
cyclic stresses, causing forced outages

19. 19
Problems Faced
• Heavy Erosion – at Riser Tubes
-- at Evaporator side Bends
• Bi Metallic Corrosion – Bracket Area of Evap Top
Bundle
• 2 Days Cooling Time for shutdown inspections
• No access to inspect Sides of Bundles
• Frequent damages to Refractory lining due to
cyclic stresses, causing forced outages

20. 20
Gas Erosion
• Evaporator Cross Section = 3.8 x 3.66 = 13.9 sqM
• Projected Area of Tubes =
100 Nos x 28mm x 3.6 M long = 10.1 sq M
NET FLOW AREA = 3.8 sq M
Gas Flow Rate = 80,000 NCuM/Hr
Gas Velocity = 80000/3.8/3600 = 5.85 m/Sec
Dust Loading = 5-10 gm/N CuM of Gas

21. 21
RISER TUBES

22. 22
SIDE BENDS
SIDE WALL

23. 23
Erosion – of Evaporator side Bends

24. 24
Improvement Plan
• Immediate:
1. Baffled the Bends to protect them
2. Shielded the Riser tubes by providing Armour plate upstream
• Long Term:
1. Monitor Tube Thinning & Schedule for Phased Replacement
2. Indigenisation of tubes with Erosion Resistant Indian Makes
• Futuristic:
Future Boilers for Plant Expansion to have lesser gas
Velocity.

25. 25
SIDE BENDS
SIDE WALL
Side Baffles

26. 26
Trigger For Tube Replacement
• Annual Tube Thickness Survey with D Meter
• Monitoring of Thinning Trend with recorded D Meter Readings
• Forecasting Thinning Rate and Procurement of Spare Tubes
• Determined value of Residual thickness to replace Tubes as
- 1.9 to 2.0 mm for Straight Part
- 1.8 mm at Bends ( Based on IBR Regn 338)
Tubes = OD 28 mm , Seamless
Original Thickness = 3mm Nominal with +0 , -10% Tolerance (GOST)
Calculated Thickness for Working Pr of 47 Bar as per GOST = 0.64 mm
Calculated Thickness for Working Pr of 47 Bar as per IBR = 1.31mm,
But Required Minimum Thickness for Coil Tubes, For Forced Circulation
and Tube OD < 29 mm = 1.62 mm (IBR Reg 338, b)

27. 27
Towards Indigenisation
• Evaporator Top Coils – 15 XM (GOST)
• Evaporator Other Coils – Steel 20 (GOST)
•Evaporator Service Conditions:
Water Temp – 270 Deg Max,
Pressure 47 Bar Max (Excess Condition)
MCR: Inlet 46 Bar, Outlet 43 Bar
Outside Temp – 800 Deg Max
Material Testing Done in our own Laboratory – QATD Dept of VSP
•Hardness
Brinnell Hardness value Varied
from 130 to 135 sample to
sample
ie Rockwell B (HRB) 72 to 75

28. 28
Material Selection
• Involved Plant Design Dept , & QATD Dept of VSP
• Consulted Dy Chief Inspector of Boilers , Visakhapatnam
• Furnished Sample tubes to BHEL
• Advice of Design Engineers from BHEL
Objectives
# Medium Carbon Steel for Evaporator service ; C = 0.2 to 0.25 % range
# Hardness to be around 80 HRB to be more resistant to Erosion
# At the same time % Elongation to be minimum 27% - Bends to be safe
in repeated Thermal Cycling (Bend R = 2D)
# Economy

29. 29
Material Selection
• SA 192
SA 210 Gr A1
SA 210 Gr C
SA 213 T11
Selected SA 210 Gr A1- CDS
• Hardness > 75 HRB; CDS will have more due
to work hardening.
• % Elongation = 30% Better Flexibility for Bends
• Thickness : Always > 3mm (as Tol = +20%, - 0%)
• Easy Availability, Weldability
Considered
Plant Design Dept of VSP Developed Tender Drawings accordingly
for Procurement of Spares from Indian Market

30. 30
Bundle Replacement
• Thickness Reduction found reaching Threshold in
Two Boilers during Annual Thickness Survey
(Residual thickness, 2.2 mm against Normal 3 mm)
• Procurement Action Initiated . Planned to Replace
next Year
Year : 2000

31. 31
Bundle Replacement
• Residual Thickness varied from 1.9 to 2.1- Time to Replace!
• Dy Chief Inspector of Boilers advised Evaporator Bundle
Replacement
• Replacement Program was approved by DOB , Hyderabad
• First Indegeneous Coil Bundle Erected in one of the Boilers in
2001
Erosion Rate Drastically Reduced in that Boiler Ever since
Thereafter All Russian Boilers underwent Indigenisation of Coils
Including Economiser Coils
Over a 10 Year Period
Year : 2001

32. 32
New CDCP Boiler Installation
• 2002-03 Planning for Capacity Expansion involving new Coke Oven
Battery
• Plan Entailed 4 More CDCP Boilers with similar Capacity
• Desired to have Design Gas Velocity as minimum as possible
• Thermax Pune Introduced the idea of Single Shaft CDCP Boilers
– As Working in Vental Steel Plant,Russia - Designed by a Finnish
Corporation Rautaruukki
– Thermax offering such CDCP Boilers to Neelanchal Ispat, Orissa

33. 33
Rautaruukki Design
• Retains the Elevation of Gas Entry Axis; Overall
Height increased
• Water Wall with Natural Circulation and Evaporators
with Forced Circulation.
• Overall Foot Print within Russian CDCP Boiler’s
• Bigger Tubes
• Bigger Pitches –Longitudinal & Transverse
• Cross Section Area gets doubled almost but Projected
area of Coils is reduced by reduction in tubings ( HSA
requirement curtailed by Water Wall).
• Marginal increase only in Overall HSA
CIRCULATING GAS VELOCITY REDUCTION OF 30 %

34. 34
New CDCP Boiler Installation
• Thermax designed Single Shaft CDCP Boiler for NINL
• We inspected Thermax Boilers at NINL : During their
Erection & Commissioning (Consultant MECON)
• Their Operation was found satisfactory
• Decided to Opt for Single Shaft Boilers; Made Specs
accordingly , under Consultancy of MECON, &
Tendered out.
• Thermal Systems, Hyderabad Bagged the Order (L-1) for
Design ,Supply & Erection of Single Shaft CDCP Boilers.

35. 35
Thermal Systems Boiler

36. 36
Thermal Systems Boiler
Cross Section Area = 5.2 M x 4.8 M = 24.96 sq M
Total Projected area for Coils and Hanger Tubes
(46 Tubes x 44.5mm x 5.2 M) + 15% =12.25 sq M
Net Flow Area = 24.96 – 12.25 = 12.71 sq M
Max Gas Velocity at MCR = 80000/12.71/3600
=1.75 m/Sec
Reduction in Velocity = (5.85-1.75)/5.85
=70.1% Reduction
4 Such Boilers in service since 2008
No Erosion Mark Reported yet

37. 37

38. 38
Problems Faced
• Heavy Erosion – at Riser Tubes
-- at Evaporator side Bends
• Bi Metallic Corrosion – Bracket Area of Evap Top
Bundle
• 2 Days Cooling Time for shutdown inspections
• No access to inspect Sides of Bundles
• Frequent damages to Refractory lining due to
cyclic stresses, causing forced outages

39. 39
Bi Metallic Corrosion
BRACKETS

40. 40
Bi Metallic Corrosion
Tube Material - Alloy Steel ( 15 XM) 1.5 Cr, 0.44 Mo
Clamp Material - Micro Alloy Steel
High apart in Electro chemical Series
During Service Period Coke Dust gets filled between pipe and clamp
During off Service period Coke Dust absorbs Moisture and turns
conductive
Electrolytic Corrosion starts, Anodising the Tube. Pittings formed

41. 41
Improvement Plan
• Immediate:
1. Stopped Water Washing
2. Placement of Silica Gel Bags inside Shaft during down period
• Long Term:
Specified Safe material for Clamp while ordering for
indigeneous tubes
• Futuristic:
Future Boilers for Plant Expansion to have this angle
considered during design phase .(Included in Specification)

42. 42
Problems Faced
• Heavy Erosion – at Riser Tubes
-- at Evaporator side Bends
• Bi Metallic Corrosion – Bracket Area of Evap Top
Bundle
• 2 Days Cooling Time for shutdown inspections
• No access to inspect Sides of Bundles
• Frequent damages to Refractory lining due to
cyclic stresses, causing forced outages
Reason: Thick Refractory Walls

43. 43
Refractory Walls
HEAT
Wall thickness = 410 mm

44. 44
Improvement Plan
• Frequent Damages:
1. Refractory Engg Dept of VSP selected better materials
to resist Cyclical Changes
2. Improved Re inforcement with steel wire nets
• Long Term:
Planned Replacement of Refractory Lining in all Boilers
undergoing
• Futuristic:
Future Boilers for Plant Expansion not to have Refractory Walls
, but to have water walls instead

45. 45
Results of Indigenisation
• Russian Boilers:
1. Mitigating the Erosion Problem with Indigeneous Coils
2. Eliminated Bi Metallic Corrosion Altogether
3. Eliminated Refractory Damage related Outages
4. Sustained the OEM Norms of Output and Efficiency
• Expansion Boilers:
1. Indigenised Sourcing.
2. Proven Freedom from all problems faced in Russian Boilers
3. Improved Energy Efficiency : 5 TPH extra steam production
per Boiler with same Heat Input Rate
4. Improved Service Life ; Reliablitiy, Availability

46. 46
Our Enablers
Directors of Boilers, AP
Dy Chief Inspectors of Boilers, Visakhapatnam
# Technical Guidance
# Timely Advises
# Boundless Co-Operation
We are indeed indebted to them………………………

47. 47
1. Salim G Purushothaman
AGM, Thermal Power Plant
2. B Ravishankar
Manager, Thermal Power Plant
3. Jeevan Kumar
Asst. Manager, Thermal Power Plant