modefied-cooler2

Clinker Coolers

    ‫ محمد عبد الحكيم‬/‫د‬

Learning Objectives Clinker Coolers

 Know the two main tasks of the clinker cooler.

 Know the definition of the cooler efficiency.  Know the cooler types and their main features.  Know symptoms and cause of the most typical

problems of grate cooler operation.  Know main design and sizing criteria of cooler types.  Know typical operating parameters of clinker coolers.

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    ‫ محمد عبد الحكيم‬/‫د‬

Clinker Coolers Content  Tasks of clinker cooler  Cooler types and definitions  Planetary and tube coolers  Conventional grate coolers

 Modern grate coolers  Trends  Typical problems 3

    ‫ محمد عبد الحكيم‬/‫د‬

Tasks of the Clinker Cooler  Clinker cooling  Heat recuperation

generating hot air  Tight for clinker and air  Provide maximum cooling velocity to avoid

unfavorable clinker phases and crystal size

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    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Energy Turnover in a Grate Cooler

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    ‫ محمد عبد الحكيم‬/‫د‬

Definitions ♦ As for other components of the kiln system, specific figures for clinker coolers refer to 1 kg of clinker. This eliminates the influence of plant size and allows direct comparison of clinker coolers of different types and sizes. ♦ Cooling air is the air which passes the clinker thus being heated up while cooling the clinker. It corresponds approximately to the combustion air requirement, only grate coolers allow additional air for better cooling. ♦ Primary air is the air which is required for proper functioning of the burner. Ambient air insufflated by a separate small fan plus the air from a pneumatic transport system, amounting from < 10% up to > 30% of the air required to combust that fuel. Some precalciner burners are equipped with primary air fans (for cooling) as well. 7     ‫ محمد عبد الحكيم‬/‫د‬

Secondary air is the hot air entering the rotary kiln via clinker cooler. Its flow is determined by the combustion of the burning zone fuel. While cooling the clinker, it reaches temperatures of 600 to over 1000°C, depending on type and condition of the cooler. ♦ Tertiary air is that part of the combustion air which is required for combusting the precalciner fuel. It is extracted from kiln hood or cooler roof, and then taken along a duct (=tertiary air duct) parallel to the kiln to the precalciner. It reaches temperatures near or equal to the level of the secondary air. Efficiency expresses the quality of heat transfer from clinker to the air which is used for combustion in the burning zone and precalciner firing.8     ‫ محمد عبد الحكيم‬/‫د‬ ♦

Middle air (grate cooler only) is extracted from the cooler roof if drying of process materials requires a temperature level which is higher than the waste air. If the quantity is small, up to 450°C can be expected at normal cooler operation. ♦ Waste air (grate cooler only) is also called cooler exit air or cooler excess air. The total cooling airflow from the fans is normally higher than the flow required for combustion (=tertiary + secondary air). The extra air, which has normally a temperature of 200 to 300°C, must be vented to ambient via a dedusting system. 9

    ‫ محمد عبد الحكيم‬/‫د‬

False air is cold air entering the system via kiln outlet seal, burner opening, casing or clinker discharge. It either dilutes secondary air thus reducing recuperated heat or adds load to the waste air system of grate coolers. ♦ Specific air Volumes are airflows per kg of clinker (m3/kg cli, Nm3/kg cli). Independent of the kiln size, airflows of cooler systems can be directly compared. ♦ Specific loads express the relation of clinker production to a characteristic dimension of (t/d m, t/d m2, t/d m3). Exact definitions vary with cooler type. ♦ Radiation losses from the cooler casing/shell are particularly important for planetary coolers, where they actively support the cooling of the 10 clinker.     ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Cooler Efficiency h cooler

h cooler =

S Q loss

Q combustion air =

Q clinker from kiln

1 -

S Q clinker from kiln

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    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Types of Clinker Coolers  Rotary:

Satellite (planetary) cooler Rotary (tube) cooler

 Grate:

Travelling grate cooler (Recupol) Reciprocating grate cooler

Fixed grate cooler (Crossbar, Polytrack) Moving grate cooler (h- cooler)  Vertical:

Gravity cooler (G-cooler) Shaft cooler (not used in cement industry)

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    ‫ محمد عبد الحكيم‬/‫د‬

Heat Exchange Types in Clinker Coolers

 Rotary:

Counter flow heat exchange in a suspension (solids in gas)

 Grate:

Cross flow heat exchange in a layer (bed)

 Vertical:

Counter flow heat exchange in a layer (bed)

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    ‫ محمد عبد الحكيم‬/‫د‬

Rotary Coolers: Planetary Cooler I

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    ‫ محمد عبد الحكيم‬/‫د‬

Planetary Cooler II

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    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Planetary Cooler (internals)

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    ‫ محمد عبد الحكيم‬/‫د‬

Planetary Cooler: Typical Problems 1) Too high clinker temp

4) Too high velocity 5) Breaker bar missing

2) Uneven clinker temp

6) Cracked kiln shell

3) Clinker dust leakage

7) Short life of high temperature lifters 25

    ‫ محمد عبد الحكيم‬/‫د‬

Satellite Cooler: Range of Control Parameters Heat Consumption Efficiency t sec air Spec. cooling air Surface load Cross section load Air velocity in tube Air velocity in elbow

3500 5000 55% 68% 730 600 0.9 1.3 1.8 - 2.0 70 - 80 < 4.5 < 25

kJ/kg % °C Nm3/kg t/m2 d t/m2 d m/s m/s

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    ‫ محمد عبد الحكيم‬/‫د‬

Tube Cooler

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    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Reciprocating Grate Coolers Terminology

Positive pressure!

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    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Significance of Fan Pressure in Grate Coolers p, T pexp = f(T) p1 > p 2 > p 3 >..... p n

pexp pexp pcli

p c li

x p1

p2

p3

p4

p5

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    ‫ محمد عبد الحكيم‬/‫د‬

Grate Cooler: Range of Control Parameters Modern Heat Consumption 3000 3500 Efficiency 71% 76% t sec & tert air * 1070 990 t sec air 1230 1170 t tert air 950 850 t waste air 300 300 grate speed 10 - 15 first grate pressure 80 - 100 Specific grate load 45 - 50 Spec. cooling air 1.8 * TA extraction from kiln hood

Conventional 3500 5000 68% 64% 890 610 940 850 240 200 10 - 20 45 - 55 35 - 45 2.3

kJ/kg % °C °C °C °C min-1 mbar t/d m2 Nm3/kg

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    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Problems of Conventional Grate Coolers  Uneven clinker distribution

 “Red River”  Air breaking through (“Geyser”)  Overheated / burnt plates  Thin clinker bed

 Poor UG-compartment sealing

-> Poor recuperation (low hth)

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    ‫ محمد عبد الحكيم‬/‫د‬

Influence of Clinker

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    ‫ محمد عبد الحكيم‬/‫د‬

Resistance and Clinker Granulometry

coarse

Air distribution:

Vc

Rf + Rg =

Vf

Rc + Rg

Vc = 1 si Rg >> Rf, Rc

Vf 37

    ‫ محمد عبد الحكيم‬/‫د‬

Conventional Grate Coolers: Gaps and Holes

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    ‫ محمد عبد الحكيم‬/‫د‬

The Key to Excellent Grate Coolers

 Correct allocation (= ratio) of air to clinker  Sustainably narrow gaps between plates rows plates and wall

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    ‫ محمد عبد الحكيم‬/‫د‬

Holcim HGRS Sizing Rules for Clinker Coolers  Grate size / specific loading

= 2.0 Nm3/kg cli

 First fan pressure:

>=100 mbar

 Resulting in estimated  



Grate speed Clinker temperature Efficiency at 3100 kJ/kg

10 to 15 strokes/min ~90 + t ambient ~70 %

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    ‫ محمد عبد الحكيم‬/‫د‬

Key Features of Modern Grate Coolers  Fixed inlet

inclined with ducted aeration  Modern grate plates

tight, high p, thermally flexible

 Fans with higher p and less V  Sections with adjustable

aeration (Trend: decreasing)  Modern side seals & plate

fixation  Roller crusher 41

    ‫ محمد عبد الحكيم‬/‫د‬

IKN Pendulum Cooler: Main Features  Fixed Inlet KIDS  Coanda Plates with built-in resistance (p)  Single grate design with sustainable gaps

 Pendulum grate suspension  Hydraulic drive with optimized characteristics  Cassette roller crusher with electric drive  Retractable heat shield  Pneumatic hopper drain 42

    ‫ محمد عبد الحكيم‬/‫د‬

IKN Pendulum Cooler

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    ‫ محمد عبد الحكيم‬/‫د‬

IKN Pendulum Grate Suspension

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    ‫ محمد عبد الحكيم‬/‫د‬

IKN Coanda Nozzle (Plate)

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    ‫ محمد عبد الحكيم‬/‫د‬

Langley-CPAG Cooler: Main Features  High Efficiency (HE) Module for ~5500 t/d  Wear protected slot plates, no fall-through

(still available: Mulden plates)  Inclined and horizontal grates  Aeration: direct (ducted), fishbone (hybrid), chamber  Compact Swing pendulum grate suspension  Hydraulic drive  Roller crusher with hydraulic drive

 Level Radar for direct clinker layer measurement 46

    ‫ محمد عبد الحكيم‬/‫د‬

Langley-CPAG: Current Technology (I)

Slot grate plate with wear protection

Fishbone aeration

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    ‫ محمد عبد الحكيم‬/‫د‬

Langley-CPAG: Current Technology (II)

“Compact Swing” pendulum grate suspension

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    ‫ محمد عبد الحكيم‬/‫د‬

Polysius Repol Cooler: Main Features  Static Pregrate with integrated air blaster  Wear protected (hardfaced) Jet Stream plates

Older installations: Jetring plates  Aeration: direct (ducted) and chamber  Center guide roller for grate  Hydraulic drive  Roller crusher with hydraulic drive  Intermediate or end crusher 49

    ‫ محمد عبد الحكيم‬/‫د‬

Polysius Static Pregrate

Cooling Air

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    ‫ محمد عبد الحكيم‬/‫د‬

Polysius Jetstream Plate

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    ‫ محمد عبد الحكيم‬/‫د‬

Benefits of Modern Cooler Technology  Smoother cooler operation  More stable kiln operation  Good recuperation (high hth)

 Control of “Red River”  Less or no clinker fall through  Smaller waste air system  Less space required  (Lower power consumption) 52

    ‫ محمد عبد الحكيم‬/‫د‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

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‫د‪ /‬محمد عبد الحكيم ‪   ‬‬

Problems with Modern Grate Coolers  Nose wear from “Sneak Air”

due to inadequate seal air (only with direct = ducted aeration systems)  Reduced life of nosering-

liners and burner refractory due to very hot secondary air

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    ‫ محمد عبد الحكيم‬/‫د‬

„Sneak Air“ (direct aeration, low seal air pressure)

pfan– p(ducts+plate)

pUG (seal air) 56

    ‫ محمد عبد الحكيم‬/‫د‬

Clinker Crusher: Hammer vs. Roller

BLOCKAGE!

NO PROBLEM 57

    ‫ محمد عبد الحكيم‬/‫د‬

New Developments (Reciprocating Grate Coolers)  Two layer cooler REPOL ZS

(Polysius) -> 2003: no longer available  Mini pendulum grate suspension

“Compact Swing” (CPAG) -> 2003: Standard  Pneumatic Hopper Drain PHD

(IKN)

-> 2003: Standard

 Internal Linear Pendulum

(IKN)

-> 2003: First unit in operation

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    ‫ محمد عبد الحكيم‬/‫د‬

Fixed Grate Coolers SF Crossbar Cooler (FLS Fuller) Main Features  First radically different grate cooler!  Fixed line; no moving rows  Mechanical flow regulators; 1 per plate

 Crossbars for clinker conveying  Standard modules; pre-installed  Different speeds across width possible

 Size < 45 t/d m2  Air installed: ~2.0 Nm3/kg

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    ‫ محمد عبد الحكيم‬/‫د‬

SF Crossbar Cooler: Crossbar Design

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    ‫ محمد عبد الحكيم‬/‫د‬

SF Crossbar Cooler: Crossbar Design

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    ‫ محمد عبد الحكيم‬/‫د‬

SF Crossbar Cooler:Mechanical Flow Regulator (MFR)

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    ‫ محمد عبد الحكيم‬/‫د‬

Fixed Grate Coolers Polytrack Cooler (Polysius)  Concept similar to FLS-Fuller Crossbar!  Fixed line; no moving rows  Flow regulators; 1 per plate  Walking floor system for clinker conveying  Standard modules  Different speeds across width possible 63

    ‫ محمد عبد الحكيم‬/‫د‬

Polytrack Cooler

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    ‫ محمد عبد الحكيم‬/‫د‬

Polytrack Cooler: Principle of Conveying

Conveying direction

(Slide by courtesy of Polysius) 65

    ‫ محمد عبد الحكيم‬/‫د‬

Moving Grate Cooler h-Cooler (CPAG):  Fixed inlet (HE Modul)  Horizontal main grate (negative inclination)  Clinker conveying by „Walking Floor“ principle  Different speeds across width possible

 No fall through -> no riddling conveyor, flat bottom  All welded steel parts (no cast!)  Modular system  Simplified compared to reciprocating cooler 66

    ‫ محمد عبد الحكيم‬/‫د‬

Features ETA Kühler •No grate riddlings •Complete autogenous wear protection •No conveying elements in the clinker layer

•Long strokes = Low grate speed •Variable stroke length over the cooler width •High transport efficiency (Slide by courtesy of CPAG)     ‫ محمد عبد الحكيم‬/‫د‬

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(Slide by courtesy of CPAG)

Principle of movement 5 lanes 1 2 3 4 5

Start position

1 2 3 4 5

Forward stroke lane 1-5

1 2 3 4 5

Backward stroke lane 1 and 4

1 2 3 4 5

Backward stroke lane 2 and 5

1 2 3 4 5

Backward stroke lane 3

    ‫ محمد عبد الحكيم‬/‫د‬

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Cooler Upgrading by Static (Fixed) Inlet I  Scope  

Replacement of first 5 to 7 rows by static inlet Replacement of 1 to 3 subsequent fans

 Benefit: 

 

Eliminates wear, fallthrough, burnt plates Improves clinker distribution Allows higher clinker bed

 Assessment  

 

Proven solution Implementation during scheduled kiln stop Relatively low cost: appr. 250„000 to 400„000 USD Short payback 69

    ‫ محمد عبد الحكيم‬/‫د‬

Cooler Upgrading by Static (Fixed) Inlet II

Polysius IKN

Satarem

CemProTec     ‫ محمد عبد الحكيم‬/‫د‬

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Grate Cooler: Typical Problems 1) Waste air temp too high

5) Strong dust cycle

2) Short life of grate plates & side plates

6) Snowman, red river

3) Excesive fall through

7) Thin clinker bed

8) Clinker dust spillage from double flap gates

4) Too hot clinker

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    ‫ محمد عبد الحكيم‬/‫د‬

Impact of Cooler on Plant Performance Recuperation

Heat Consumption

Fluctuations

Kiln Operation

Dust Cycle

Wear

Plate Life

Kiln Availability Maintenance Building Volume

PERFORMANCE

Clinker Cooler Power Consumption Clinker Temp.

Handling Cement Quality Grinding System

Clinker Quality

Grindability

Waste Air Flow

Filter Size 72

    ‫ محمد عبد الحكيم‬/‫د‬