DESIGN OF FURNACE & REFRACTORY LINING
By
MK Maity
(Materials & Corrosion Section, STC-J)
v
THE PERFORMANCE OF REFRACTORY LINING DEPENDS ON

Lining Design

Selection of Material

Installation

Operation Of Furnace

Maintenance
2
OBJECTIVE OF A GOOD LINING DESIGN
 Operation & Production At Optimum Cost &
Expenses Of Refractories Used
 To Obtain Optimum Trouble Free Service Life
 To Have Reliable & Dependable Lining System
 Ease Of Material Procurement
 Ease Of Installation
 Future Ease Of Maintenance
 Ease Of Repair
3
DESIGN & DETAIL ENGINEERING
Detail Of Lining :
•
Materials Quality
•
Thickness
•
Heat Transfer Calculations
•
Shape & Size Of Bricks , C.F.Modules, Etc.
•
Dimensional Tolerances,
•
Laying Pattern
•
Lining Details Of Openings, Corners,
Junctions
•
Type Of Mortar & Mortar Joint
•
Type Of Expansion Joint, Location & Width
4
DESIGN & DETAIL ENGINEERING
Detail Of Lining :
Anchor & Hard-wares:
•
Anchor
& Support Quality
•
Anchor
Design , Dimension, Height
•
Anchor Spacing & Orientation
•
Vapor Barrier ( SS, Al foil)
•
Corrosion Resistant Coating
5
DESIGN & DETAIL ENGINEERING
Refractory Materials:
•
•
•
Material Specifications & Test Methods
Quantity of Materials & Overages
Suppliers
Installation:
•
•
•
•
•
•
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Installation Method
Sequence of Installation
Selection of Contractors
Lining Dry Out
Inspection Test Plan & Acceptance Criteria
Special Requirements
LINING SYSTEM
1. Brick Lining
• Different Shapes
• Insulating & Dense Type
• Type of Mortar
2. Monolithic / Concrete Lining
3. Ceramic Fibre Lining( Blanket &
Module)
4. Combination
7
FACTORS FOR LINING DESIGN & SELECTION OF MATERIALS
1.
Operating Temperature
2.
Mode Of Operation (Intermittent/ Cyclic, Continuous)
3.
Furnace Atmosphere (Oxidizing, Reducing, Neutral)
4.
Furnace Pressure ( +Ve, -Ve, Neutral)
5.
Geometry Of Furnace
6.
Type Of Furnace (Static, Rotating, Tilting)
7.
Interface Temperature Between The Layers , Temp Gradient
8.
Expected Casing Temperature And Heat Loss
8
MAJOR FACTORS CONSIDERED FOR LINING DESIGN
9.
10.
11.
Requirement Of Furnace Efficiency
Physical Abuses Such As Abrasion, Erosion Etc.
Thermo-chemical Attack : Corrosion
12.
Function Of Furnace: Heating Of Solid, Melting, Heating Of
Gases, Hydrocarbons, Etc.
13.
Gas Composition Within The Furnace (Sulfur, Sodium,
Potassium, Chlorine, Hydrogen Etc.)
14.
Expected Life Of Furnace
15.
Cost And Economics
16.
Ease Of Installation,
17.
Future Ease Of Maintenance & Repair
9
SELECTION OF REFRACTORIES
Chemical Composition
Apparent Porosity
Bulk Density
Co-efficient Of Thermal Expansion
Permanent Linear Change
Refractoriness Under Load
Pyrometric Cone Equivalent
10
SELECTION OF REFRACTORIES
Thermal Conductivity
Spalling Resistance
Performance Under Various Gaseous Atmosphere
Permeability
Mechanical Strength (Room Temperature & High
Temperature)
Abrasion / Erosion Resistance
Resistance To Chemical Attack
11
HEAT FLOW CALCULATION
INPUT:








Operating Temperature
Ambient Temperature
Operating Pressure
External Wind Velocity
Thermal Conductivity
Emissivity
Heat Flow Direction
Inside Gas Composition
(Hydrogen, Etc.)
12
OUTPUT:
 External Shell Temperature
 Interface Temperature
 Heat Loss From Surface
THERMAL / HEAT FLOW CALCULATION
HOT
Layer 1: IFB, Gr. 28
Layer 2: IFB, Gr. 23
Layer 3: Fibre Block
1100°C
Layer 4: Fibre Block
800°C
Layer 1: MW Concrete
Layer 2: CRF Board
1260°C
Layer 3: Fibre Block
1000°C
Layer 4: Fibre Block
800°C
Layer 1: CRF
Modules 1430°C,
192kg/m³
Layer 2: CRF
Blanket 1260°C
Layer 1: CRF
Blankets
1430°C, 160kg/³
Layer 2: CRF
Blanket 1260°C
Heat Flow Calculation for: tAMB=27°C, tINS=1200°C, wind=0m/s, ε=0.95
tOUTS=72°C
qloss=576 W/m²
tOUTS=78°C
qloss=676 W/m²
Water Content≈92kg/m²
13
tOUTS=73°C
qloss=601 W/m²
tOUTS=69°C
qloss=528 W/m²
LINING THICKNESS
Factors Determining Thickness :
 Operating Temperature
 Corrosion, Erosion Etc.
 Thermal Calculation
 Design Casing Temperature
 Strength
 Installation Method
 Service Life
14
LINING STRUCTURE
AND SELECTION OF MATERIALS
SINGLE LAYER:
 Low Operating Temperature
 Less Severe Conditions
MULTI LAYER:
 High Operating Temperature,
 Low Heat Loss Requirement
 Severe Conditions
COMBINED:
 Combination Of Brick, Block, castable,
Ceramic Fibre Material
15
LINING FOR MOLTEN STEEL / SLAG
Linings Consist Of A Safety Lining And A Working Lining
• Safety Lining Is Usually Provides Security
Insulation For The Vessel
&
• Working Lining Is In Direct Contact With Steel And
Slag.
• Zone Wise Different Refractory To Match The Conditions
It Is Exposed To Have Balanced Deterioration
16
REFRACTORY WEAR MECHANISMS IN STEEL PLANT
– Corrosion
• Chemical Reactions Between Slag Components (FeO, MnO
and SiO2) & Refractory
• Refractory Is Soluble In Steelmaking Slag
• Corrosion Can Be Minimized By Saturating Slag (With MgO
From Dololime & Controlling Over Oxidation )
– Oxidation
• Oxidation Occurs When Carbon In Refractory Reacts With
Oxygen From Slag (FeO) Or The Atmosphere And Burns
• As The Carbon Is Oxidized The Refractory Loses Its Strength
– Erosion
• When Liquid Steel Or Slag Flows Over A Refractory Surface &
Abrades Surface
17
HEIGHT OF LINING
Brick-wall
Mostly Self Supporting Type & Height
Is Determined On Basis Of :
Stability Of Wall
 Load At Bottom
 Vertical Expansion Etc.

Monolithic Lining
 No Restriction In Height,
 As Weight Of Refractory Is Uniformly
Distributed Amongst The Anchors
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THERMAL EXPANSION OF LINING
•
Expansion Joints In Brick Lining Are
Necessary In Order To Protect The Lining
And Shell Against Forces Due To Thermal
Expansion Of Brick.
•
Expansion Joints In Monolithic Lining Often
Not Necessary Since Anchor Fitted To The
Furnace Shell Allow Limited Movement Due
To Thermal Expansion.
•
Expansion Joints Are Necessary In
Monolithic Lining That Are Not Supported By
Anchor
•
Size Of Expansion Joint Depends On Drying
+ Heating Shrinkage, Expansion Of Material
, Shell / Casing Etc.
19
SHRINKAGE OF LINING :
 Monolithic Refractory Lining Usually Shrinks During Post
Installation Drying And When Cooled After Heating.
 To Protect The Lining From Damage Due To Shrinkage,
Joints Are Left At Appropriate Intervals So That These May
Take Up The Shrinkage.
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ANCHORS FOR REFRACTORY LINING
Function Of Anchor:
 To Hold Refractory in Position
 Provide Support For Wall &
Arches & Flat Roof
 Prevent Bulging & Bowing Of
Lining
 Allow Horizontal & Vertical
Movement Of Lining
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TYPES OF ANCHOR
• Metallic Anchors
• Ceramic Anchors
Metal Anchor







L Type
V Type
Y Type
Hexmesh
Chain Link Wire Mesh
Anchor For Ceramic Fibre Lining
Special Anchor
22
DESIGN OF ANCHOR SYSTEM
 Anchor Quality
 Diameter Of Anchor Rod
 Anchor Configuration
 Anchor Spacing
 Anchor Orientation
 Anchor Height / Cover
 Plastic Cap / Coating On Anchor
23
SELECTION CRITERIA OF ANCHOR SYSTEM
 Type Of Lining & Lining Thickness
 Type Of Refractory Materials
 Furnace Operating Conditions
 Position Of Lining ( Vertical, Horizontal,
Inclined, Floor, Circular Etc.)
 Mechanical Movement Etc.
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CERAMIC ANCHOR
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STEEL FIBRE REINFORCEMENT IN REFRACTORY CASTABLE
ADVANTAGES:
•
Higher Tensile, Flexural And
Compressive Strength
•
Improved Resistance To Damage From
Vibration, Impact And Thermal Shock
•
Better Resistance To Cracking
•
Better Performance Under Abrasive
Conditions
26
TYPE OF STEEL FIBRES & THEIR CHARACTERISTICS :
•
Type Of Fibre
: Steel Wires, Thin
Steel Wares, Melt Extraction,
Shaving Thick Steel Plates
•
Dia. Of Fibre (D)
: 0.3 Mm To 0.5 Mm
•
Length (L)
: 25 Mm To 30 Mm
•
Aspect Ratio (L/D)
: 50 To 100
•
Material Quality
: SS 304, SS 410, SS 310 Etc.
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SULFURIC ACID CONDENSATION
Flue gas constituents:
•
•
•
•
H2O (Steam), SO2 & SO3 (Gases)
CO, CO2 , N2 , NOx , Cl, (Gases)
H2SO4 , HCl, HNO3 (Gases)
Compounds of Na, V, Ash Etc.
(Depending of type of fuel, furnace charge, etc.)
S + O2
SO2 (Gas)
( Conversion ~ 1-5 %)
SO2 + O2
SO3 (Gas) + H2O (Steam)
SO3 (Gas)
H2 SO4 (Gas)
Temp< Dew Point
120-160 0C
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H2 SO4
(Liquid)
PHYSICAL BARRIER INSIDE LINING
•
Metallic Foil / Sheet ( SS, Al) Between Refractory Layers
•
Thickness 0.1 to 0.15mm
SS Sheet
Mainly For Cold Wall Design Furnaces:
•
•
Casing Temperature Is Maintained Approx. 60 to 100 0C.
Very High Thermal Efficiency Is Expected
 Heater,
 Primary Reformer, Cracker
TYPICAL SS SHEET BARRIER
SS Foil Over Insulating Board
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THANK YOU