Ta.ble of Content

Objectives

1. Checks prior to start-up

Kiln Preheat Preparation

2.1. Burner Pipe Alignment

2.2. Kil¡ Refractory Preparation

2.3. Burner Pipe Lining

Kiln Preheat Schedule

3.1. Parameters Monitoring (per t¡pe of kiln)

3.2. Tire Creep

3.3. Turning Schedule

3.4. Kiln Start-up Process Data Sheet

3.5. Kiln Lining Preheat Schedule

4. Feeding Raw Materials

5. Start-up Post-Audit

2.

3.
MPT Best Pructíces:

KILN START-UP PROCEDURES

Objectíves:

Develop master procedures for heating up the pyro-line in a standard, safe and efficient

manner (minimum transition periods, no aborted start-ups) while assuring the integrity of

the equipment and the refractory and staying in environmental compliance. The procedures

will address the quick compliance with clinker quality objectives.

Then, each plant would customize these master procedures to the specific characteristics of

their equipment and develop more detailed checklists and SOP's.

7,0 ßecommended Checks Príor to Kíln Størt-Up (Feed On)

1.7. Kíln Feed systems

a The kiln feed system should be run in a recirculation operation and calibrated is the

system allows. If the system does not allow for a complete run, then a means of

determining the readiness of the system should be developed.

o If no recirculation system is in place, then the feed system should be run for few

minutes, checking for proper operation and system leaks.

0 Test run the dust evacuation system including elevators, screws, pumps etc. Continue to

run this system throughout the wann up.

1.2. Cooler ønd Clinker Høndling

o Test run all cooler drives and inspect for loose grates after running. Check the alignment

of the cooler while running. Continue to run the system for at least 12 hours to ensure its

mechanical integrity.

o The following equipment should also be run and checked: Clinker Cooler Breaker, Vent

Fan, Cooler Fans, and all downstream clinker handling equipment. (1.e.: drag

conveyors, belts, pan conveyors, gates etc.) All equipment must be checked for
alignment, motor direction and automated control. Ensure that fan dampers or variable

speed motors can operate at full range.

o Test the operation of all of the cooler Plattco valves and check for a good seal.

o Ensure the calibration of all pressure transmitters for the cooler fans.

7.3. I.D. Føn

a Test run the I.D. fan and test for proper rotation, controls from the freld and computer as

well as check for leaks

7.4. Coøl Conveying system

a Test run the coal mill circuit and fans. Ensure that all of the damper controls are

working properly.

a Test run the coal mill feed system as early as possible. If the system has been calibrated,

initiate a method of verification of the weights.

t The entire coal mill circuit should be run as early as possible so that checks can be made

for leaks. If leaks are present, they can be corected prior to start up so that it will not be

delayed.

7.5. Kíln Bøghouse or ESP.

a Follow the established start-up procedures (Process or Maintenance) for new bag

installations. This will include any precoating procedures, leak tests or air load testing.

1.6. Preheat System (These ítems to be done well beþre needed)

a Ensure all locks are removed from the system

o Verify all hoses and connections are in place for the fuel and air supply systems

t All valves in their proper positions for operation

I Ignition source ready and available at kiln hood

o Test run burner axial, swirl and transport air systems and check filters
7.7. Møteríøl Flow Checkfor Preheøter Plønt

a Verify all tower chutes are clear by dropping mill ball through cyclone and chutes

o Verify all tower tipping valves are working properly. Open and close manually

7.8. Burner Pípe Alígnment

o Each plant should have a burner pipe alignment procedure that must be followed. The

burner pipe should be aligned cold and then the position should be verified after all of

the peripherals are connected. Failure to do this could mean improper alignment and

thus inefficient fuel consurnption, poor clinker quality and decreased refractory life.

o Attached is an example of such a procedure.

7.9. Common Pre-checks

a Ensure the proper direction or rotation of all fans, scre\rys, conveyors, clinker breaker etc.

a Checks should be made on:

o Oil in reducers

0 Equipment properly closed up

a Locks removed and switches in

o Auxiliary kiln drive motor function

a Check airflows on all fans that have been altered during the turnaround.

In short, a complete checksheet should be developed so that the plant can be assured that all of

the required checks are completed on all equipment. The check sheets should include enough

room for comments, assigned responsibility to one person and an area where the person

responsible can sign his/her name indicating that the check is complete.
2. Kíln Preheøt Preoøratíon:

2.7. Burner pípe ølígnment

Example

a.) Insert the burner pipe into the kiln with the kiln doors open.

b.) Ensure that the burner pipe is set at the desired distance into the kiln Record the distance of

the burner tip into the kiln. The kiln expansion must be measured to determine the exact

position of the burner pipe into the kiln.

c.) Once the burner pipe is set, hook up the axial, swirl and transport air lines

d.) When all air lines have been installed, the kiln hood doors can be closed

e.) When the hood doors are closed and secure, insert the laser level into the center of the

burner pipe.(feed end)

f.) Make sure that the laser is set in the center of the pipe. This is accomplished by wrapping

the end of the bumer pipe with plastic. This allows for sight of the laser beam.

g.) With at least two people outside of the kiln and two inside, take measurements of the

position of the laser beam at at least three places in the kiln. This should include the start of

the burning zone (30 feet), the upper transition zone (80-85 feet) and on the feed shelf. It is

important to know the thickness of the brick prior to measurement to determine the proper

position of the burner pipe.

h.) Through radio contact, make the necessary adjustments on the burner pipe carriage so that

the laser beam hits each point of measurement.

i.) Once the points have been met, it is important that there is no further movement of the

burner pipe prior to start up.

j.) Measurements on the burner pipe carriage screws as well as pipe height relative to the

concrete floor are to be taken and recorded as a reference prior to start up. These

measurements should be checked periodically throughout the campaign.

k.) When the hood doors are closed, the area can be sprayed with a light coating of refractory

to eliminate any inleakage of air.

The overall objective of this procedure is to know exactly where the burner pipe is in

relation to the kiln.

2,2, Kíln Refrøctory prepørøt¡on

Purpose: To properly manage the installation of refractory during a scheduled or

unscheduled shutdown, and to follow established procedures for preheating the

kiln systern for maximum brick life.
The refractory best practice should be consulted to determine proper method of

preparation.

longevity of the lining. During a major turnaround it would be well for plants to consider

hiring an experienced refractory installation specialist to supervise the ongoing lining

replacement or ensure that the installer is familiar with the various installation techniques

that are available.

Proper Refractory Preheating and Curing.

The following information has been collected from a large number of refractory suppliers. This

infonlation should be used only as a guideline for proper refi'actory management. In all cases

the plants should review the intended operating procedures with the refi'actory suppliers as the

amount of refractory types and materials vary extensively.

Each plant should consult and insist on having a representative from the refi'actory supplier on

hand during the installation and curing of the material chosen. This process could be included

in the purchasing agreement.

2.3. Burner pípe líníng

rammed refractory.

Note: The poured castable refractory must be allowed to cure for a rninimum of 24 hours

before removing fonns or attempting to properly bakeout the refi'actory.

= 

To properly bake out the poured castable or the plastic rammed refractory, the following

schedule should be used as a guideline. All plants should check with their respective

suppliers for specific curing schedules for various types ofrefractory.

The refi'actory lining should be increased from ambient to 200 degrees C at a rate of 50 degrees

C per hour. The temperature should be held at200 degrees C for one hour per inch of refractory

thickness. The ternperature should then be increased from 200 degrees C to 600 degrees C at a

rate of 50 degrees C per hour and again held at this temperature for I hour per inch of refi'actory

thickness. The lining should be allowed to cool back to arnbient without induced draft. The

bumer pipe can now be installed in the kiln or put into storage if it is a spare.
Burner Plpe Llnlng Preheat Schedule

example - 4 lnch refractory llnlng

l-ññæ;ü-ol

3. Kíln Preheu,t Schedule :

3.7. Pørømeters to be trucked duríng preheøt

It is essential that plants have a preheating schedule determined prior to the start up. The

start-up program, which mainly determines the kiln temperature increase per unit time and the

timing of the introduction of raw feed, must consider a number of factors such as the type of

refractory material, design of the kiln systemo mechanical systems etc. The following points

should be recorded during the preheat.

3.1.1. Preheater/Precalciner

a stage #l exit oxygen

lt Stage #4 or Precalciner temperature

o Feed shelf Temperaturelkiln exit temperature

a Feed shelf or kiln exit oxygen

t Burning zone temperature(shell scanner)

ô Tyre Creep
a Tyre temperature and the bearing temperatures

0 Kiln hood pressure

a Fuel consumption

o Kiln turning schedule

o Thermal expansion of the kiln

a Monitor ESP/Baghouse (including gas & opacity analyzers) - turn on as soon as possible

3.1.2. Long \iletll,ong Dry Kilns

o Feed shelfoxygen

a Feed shelf temperature

a Chain temperature

o Burning zone temperature(shell scanner)

a Kiln turning schedule

ô Tyre Creep

I Tyre temperature and bearing temperatures

,t Kiln hood pressure

o Fuel Consumption

o Kiln turning schedule ,) Thermal expansion of the kiln

I Monitor ESP/Baghouse (including gas & opacity analyzers) - turn on as soon as possible

3.2, Tyre Creep

3.2.1. Purpose of tyre creep control:

From a tyre creep point of view, the minimum heating-up period is determined by the time

required to stabilize the temperature difference (and hence the clearance) between the kiln

shell and the tyre, since the shell will heat up faster than the tyre.

Tyre # 2 is particularly critical. Too rapid heating can result in a constriction of the kiln

shell, which will cause permanent deformation if the yield strength of the kiln shell material

is exceeded. This in turn will cause excessive play in the tyre (tyre slip) after the normal

working temperature is regained, as well as increased ovality of the kiln shell, a factor which

may contribute to excessive refractory lining wear.

As a general rule, the tyre creep (the relative motion between the tyre and the kiln shell)

should be monitored at regular intervals or continuously with a kiln shell scanner if

available, manually if not. If the tyre creep is too low or non-existent, the heating-up

process should be slowed down or intemrpted until a measurable arnount of relative

movement is established. For this reason, the tyre creep may become the limiting factor in

determining the heating-up schedule.
Every tyre has its specific designed cold clearance that allows a maximum temperature

difference between the kiln shell and tyre during heating. If the temperature difference

exceeds the maximum value during the heating-up schedule, the shell below can be

plastically deformed due to restricted expansion. To avoid such a deformation, solne plants

have established artificial heating or exterior heating elements on the tyre themselves, or

defìne a start-up sequence for the shell cooling fans. This allows for controlled heating of

the tyre in line with the heating-up schedule for the kiln. The thermal expansion for each

unit can be controlled so that defonnation of the kiln or the tyre can be avoided.

Proper clearances for tyres during heat up will range from a minimum of 5 rnm to a high

of 25 mm.

3.2.2. Procedure for tyre creep monitoring

Purpose and Scope:

To monitor and react to Kiln Tyre Slippage levels in order to prevent damage to the Kiln Shell,

Tyre, and Refractory. It is irnportant to note that all support tyres must be monitored during a

preheat, however, the tyres in the area of the burning zone are the most critical and susceptible

to temperature changes. Due to the potential for darnage, this monitoring operation should be

considered critical in a kiln start up with dedicated manpower provided.

Specific Points:

a.) Slippage and temperature measurements during a kiln startup should be taken in the field

only. Do not rely on thermal irnaging scanners for temperature or slippage indication during

a preheat. Use thermostatic pencils when necessal'y. Slippage and temperature

measurements must be taken at each tye every t/zhow during a preheat.

b.) The temperature difference between the tyre and the shell must be less than 125 oC at

all tirnes during the preheat. The shell temperature must be taken on both sides of the tyre.

The tyre temperature must be measured on the side of the tyre and not the rolling face.

Measure both the uphill and downhill side of the tyre.

c.) If the temperature difference rises above 125 oC, hold the kiln heat input until the

temperature falls below the 125 oC. When the temperature is below 125 "C, resume the

preheating schedule.

d.) The minimum tyre slippage per kiln revolution is 8mm.

e.) If the kiln tyre slippage falls below 8mm/rev, hold the kiln heat input until the tyre

slippage reaches 8mm / rev. At 8mm / rev, resume the preheat schedule.
f.) If the kiln tyre slippage falls below Smm / rev decrease kiln heat input until the tyre

slippage reaches 5mm / rev. Ensure that the shell and the tyre temperature are rising at the

same rate. At 5mm +, hold the kiln heat input until the slippage reaches 8mm *, at this point,

resum€ preheating schedule.

g.) If there is no measureable slippage, follow the instructions for slippage below Smm/rev

with aggressive moves on heat input. If slippage has not returned inYzhonr, shut down.

h.) If tyre slþage is in excess of 25mm plant personnel should investigate the shimming of the

tyre. Excess slippage of the tyre can cause problems with kiln ovality which may result in

shell, refractory and nose ring damage.

Notes:

encounter a slþage problem.
An example of tyre creep monitoring is shown below:

Date

Temperature and Slippage Measurements

Kiln

Tyre # I Tyre#2 Tyre # 3

fime Down Hill Tyre Up Hill Sliooase Down Hill Tyre Up Hill Slippase Down Hill Tyre Uo Hill Slippase
Note: Tyre temperature is determined by taking the measurement on each side of the

tyre. The recorded temperature should be the average of the two.

information. Temperature OR Slippage alone is meaningless. Both parameters must be

recorded for proper assessment. Modify record sheets accordingly to record this data every

Yzhour.

Example of an effective measuring system for tyre slippage

(Install 3 per tyre at 12r 4,I o'clock)

Side View

Slippage Indicator (Pointer)

Measuring Device \*

^/ 

Kiln Tye

Tyre Shims

Kiln Shell

Top View

Kiln Tyre

I 2 3 4 5 6 cm
3,3. Turníng Schedules:

The purpose of a turning schedule is to ensure slow, uniform heating of the kiln and it's

refi'actories. Turning schedules are based on an increase in temperature over time. A good

turning schedule will allow for the expansion of the refractory and kiln shell so that the brick

remain in place and the shell expands uniformly along its longitudinal axis.

Turning Schedule: Too Slow

Overheating of the refractory and the kiln shell

Duck-nesting or sporadic gouging of the refractory

Shell and refractory damage.

Too Fast

Poor heat distribution

Longer preheat time due to poor transfer of heat

Potential for spiraling of brick

An example of the turning schedules for a kiln is shown below:

TEMPERATURE OF EXIT GAS

AT KILN INLET

KILN TURNING PROCEDURE WITH

AUXILIARY DRIVE

UP TO 120"C KEEP THE KILN STOPPED

120'c ro 2100c TURN 90'TO 12OO EVERY 45 MINUTES

210"c To 450"c TURN 9OO TO I2O'EVERY 30 MINUTES

450.C TO 600.C TURN 9OO TO I2O" EVERY 15 MINUTES

6000c To 750.c TURN 90'TO I2O'EVERY IO MINUTES

75OOC UP TO FEEDING CONTINUOUS TURNING

As a compromise, the kiln should be periodically turned i.e.: rotated a fi'action of a turn,

During the initial phase until the sintering zone temperature reaches approximately 900 'C

(1650 oF). After this phase, the kiln can be rotated continuously in a nonnal manner through the

auxiliary drive.
Date:

3.4. Kíln Størt Up Process Døtø

Time of Flame On: Preheat Schedule:

Hours

Hour of

the

Preheat

Tyre

Creep #l

Tyre

Tyre

Creep #2

tyre

Hour of

the

Day

Chain

Gas

Temp

Fuel

Rate

Feed End

Oxygen

Swirl Air

Setting

Axial Air

Setting

Feed

End

Temp

I.D. Fan

Speed
3.5. Kíln Preheøt Schedule

The following is a guideling for preheating Kiln refractory brick linings after a major shutdown and

a short turnaround.

HEATING.UP GRAPH FOR ROTARY CEMENT KILNS

1 300*

{START OF MATERTAL FEED ACCORD¡NG

TO

{K|LN TYPE AND OPERAT|NG PROCES

1200

300*

0369't215182124273033363942

Heating-up Time, hours

* Lining Temperature under the Flame

HEATING.UP CONDITION

CURVE 1: HEATING-UP AFTER LIMITED REPAIRS THERMAL GRADIENT - 30 TO 35oc/h.

CUR\/IÌ 2: HEATING-UP AFTER COMPLETE RE-LINING THERMAL GRADIENT - 20 TO 25"Clh.

Most suppliers of refractory materials recommend for the start up of kilns after major

turnarounds with monolithic linings, a maximum heating -up rate of approximately 25 "C /h in

the sinteringzone up to a temperature of 900 oC. After reaching 900 oC, heating up can

continue at arate of 50 oC up to the working temperature.

o

1 000

900

o

o

Ë 8oo

g

tr

; 700

G

o

Ë 600

E

o

CL

$ soo

ao(l,

sr4oo Ë

x

o

E soo

v

200

100

0
After a minor shutdown (less than 24 hours) where no major lining is replaced, refractory

suppliers recommend a heating-up rate of 50 'C /h.

V/hat is not shown in the graph above is a stepped approach to the heat up schedule (see followup graph on the last page. What this means is that there should be a holding pattern on the

temperatures in the kiln system in at least two separate tempemture ranges. The first holding

pattem should be made in the initial stages of the heat up procedure. This means that when the

sintering zone temperature reaches approximately 300 oC, the temperature should be held

constant for approximately 3 hours. This procedure should be repeated again once the sintering

zone temperature reaches approximately 500 to 550 oC. This procedure allows the refractory

material to "catch up" with the gas temperature. The heat penetrates the refractory material as

well as the metal casings and reduces the possibility of non-uniform expansion and tyre creep

ptoblems. This procedure can of course be rnodified based on the amount of refractory work

that has been completed during the shutdown.

4. Feedíns of Ruw Møteríøls

4.1. P r e h e ut e r s/P r e c al c in er s :

Raw material feed can be started when the temperature curve in the kiln system

approaches operational conditions or as soon as the prccalciner and preheat temperatures profile

is ready for feed.

The period between the start of the kiln feed and its anival at the sintering zone is the

most critical with respect to tyre creep because the fuel supply must be increased rapidly to

compensate for the heat absorbed by the processing of the raw material. Close attention must be

made at this phase so that slip is continuously present. If slip of the tyre ceases,

countermeasures must be taken to correct the situation.

Feed rnay be introduced into the kiln system prior to amiving at optirnal temperature as a

measure to coat the refractory linings. Only small amounts can be introduced so that there is not

a deterioration of the heat gradient.
4.2. Long ll¡et ønd Dry Kílns:

Kiln chains or other heat exchange systems should not be exposed to excessive heat

prior to the introduction of feed. Excessive heat can damage and potentially cause fires in the

metallic systems. For this reason, material feed is usually started after the sintering zone

temperature reaches 950 degrees C and the kiln is rotated continuously by using a feed rate of

l0o/o to the nominal throughput.

The feed rate is then continuously increased depending on the kiln exit gas temperature,

the specific heat consumption and the burning conditions. The kiln speed is increased

proportionally to the feed rate.

Graph the specific heat consumption versus the feed rate, oxygen, kiln amps and kiln speed.

s.t. Objectíves of ø post øudít

A post audit of the start-up to analyze deviations from the planned schedule should be

systematically done between the production coordinator and the kiln operators.

Reasons for deviations should be identified and recommendations to improve the next kiln startup should be drafted and when necessary, incorporated into the SOP. CRO involvement is

essential to the success ofproper kiln start ups.

s.z. Revíew ltems:

-Preheat temperatures and oxygen control-actual vs. plan

-Timing of preheat-actual versus plan

-Specifi c heat consumption/lrlOx values

-Tyre Creep report

-Axial and swirl settings

-Review of check sheets - explanation of variances

-Review of problems incurred during preheat

-# of incidents within two weeks after start-up

-Amount of tirne to full production

Develop the above into a table that shows the variances and explanations for the variances
fi. Example offollow-ap grøph:

The graph below can be used to compare the actual versus planned start-up control parameters.

24 HOUR PREHEAT SCHEDULE

8 9 10 11 121314151617 18192021 222324252627 28

HOURS

1000

900

800

700

u¡ 600

ú, Ð

tÉ soo

EI

o.

=H ¿oo

300

200

100

0

-I-STG 4 TEMP

+STG 1 TEMP