kiln emergency ys

Fully Understand The Situation

The Decision Taken Must Be Applied Quickly and Properly

What Kiln Operator Should Do In Emergency Situation

Know What Must Be Done During This Emergency Condition

Understand the consequences of any action might be taken

Red Spot On Kiln Shell

Refractory material fell down and lost in any part of the kiln system

Emergency Condition In Any Rotary Cement Kiln Are:

Burning zone temperature dangerously very high

Unburned raw material in the kiln outlet and cooler

Dangerously high kiln inlet temperature

1

2

3

4

5

Main burner flame shape is distorted

Failure of precalciner burner or burners


Failure of by-pass system

Red-hot clinker coming out from the cooler

High kiln-hood positive pressure

6

7

8

9

10

Cooler drive or clinker transportation stopped

Snow man in the first stage of the cooler


Rush of clinker materials in the kiln

Preheater cyclones blocking with feed material

Power failure

11

12

13

14

16

Loss of kiln feed 15

Red Spot On The Kiln Shell 1

Red Spot indicates loss of bricks in kiln

different zones

Some of this Red Spots can be dealt with and disappear

While other Red Spots will be persistent and will lead to eventual kiln shut down


The danger of operation with red spots especially in very hot countries lead to:

Severe damage to the kiln shell

The shell can be punctured in the end


Red spots are diagnosed by:

Visual inspection

Temperature over 480ºC on shell scanner or hand pyrometer

Bricks found with clinker either in the burning zone or with clinker on the clinker conveyor.


Action To Be Taken In Case Of:

Continue normal operation of the kiln

Start cooling this spot with fans

The Red Spot is located in upper transition zone or in the burning zone

Shorten the flame to bring the black feed area under the burner nearer or over the red spot to try to form a new coating inside the area empty from bricks

A



Keep the burning zone temperature at its normal range

The Red Spot is located in upper transition zone or in the burning zone

A

Try in the period after the disappeared of this red spots to have easy to burn kiln feed.



Kiln should be immediately shutdown

Large Red Spot especially if located under the tyre or very near to welding seams in the section of the tyre.

B


How to make it never or rarely happen again:

Be sure that there is no excessive overheating of the kiln-burning zone

Be sure that flame doesn’t directly hit the brick or cause localized coating erosion.

Try to minimize kiln shut down or upset conditions

Install a high quality refractory bricks in the kiln & employ proper refractory installation techniques & methods with proper & professional supervision

Preheater Areas

Kiln nose ring

Refractory fall down or lost in a part of kiln system

2

Falling of bricks in the following areas are potential reasons for stopping the kiln:

Kiln Inlet

In Kiln before upper transition zone

Kiln fire hood

By Pass area before quenching air area


2

Falling of bricks in the following areas are potential reasons for stopping the kiln:

Cooler walls in the hot zone area of the cooler

Cooling end of kiln shell before the outlet nose ring

Kiln nose ring


2

Detection of the area or areas where the brick lining or castables are lost can

Loose bricks are found with clinker on clinker transportation system

Area parallel to kiln axis, and the shell is very hot or red in this area

Rapid rise in the area where the refractory is lost, until it becomes red hot and deformed.


2

Detection of the area or areas where the brick lining or castables are lost can

Thermal damage to the kiln shell or the steel structure of other areas and eventual loss of that parts with possibility of false air to the system and possibly hot material leakage to outside of the kiln system.

Loose bricks are seen with the clinker bed in the burning-zone

The area where the refractory lining is lost will increase on area


2

How to prevent Refractory fall down

Procedure of installing bricks should be revised

and the proper techniques and methods of applying refractory material in the kiln system.

Quality of the refractory used in this area should be

questioned and investigated

Suppliers should be contacted for help if needed


2

How to prevent Refractory fall down

Kiln ovality and kiln alignment should be monitored

and checked in the proper time to keep the kiln in

proper mechanical conditions.

Kiln techniques and procedures should be revised

and investigated to for any excessive rotating of

the kiln during shut down or start up or when it is

cold during the shutdown it self.

Burning Zone Temp. Dangerously Very High

Coating will be dripping off the kiln burning zone wall

3

In abnormal operation condition, the following can be detected

Clinker start to balling in the burning-zone and this phenomenon is called sausage

Sliding clinker bed will be found in the burning-zone


Burning zone temperature is too high

3

In abnormal operation condition, the following can be detected

First part of the cooler will have snowman

Burning-zone color will be white-faint yellow

Cooler under-grate pressure will be very high


Rapid failure of bricks in the burning zone will take place due to the loss of coating and excessive heat on the bricks

3

Result of such condition will be the following

Red spots on the kiln shell that could be a large area with faint red-hot color, big or small area with red-hot color

Thermal damage to cooler plates and kiln hood area components will be very costly


Reduce fuel rate to minimum until sausage is stopped

3

Action that should be taken in such conditions

Increase kiln speed by 0.5 rpm more to help breaking the sausage in the burning-zone.

Increase the air in the cooler hot zone to maximum with creating positive pressure in the kiln hood.

Burning Zone Temp. Dangerously Very High 3


Reduce primary airflow to control the temperature of the flame

When the sausage disappears and the agglomeration disappears, start to restore the condition of the burning-zone to normal again by: reducing kiln speed and increasing the I.D. fan speed while increasing the fuel rate


Reduce fuel rate to minimum until sausage is stopped

3


Increase kiln speed by 0.5 rpm more to help breaking the sausage in the burning-zone.

Increase the air in the cooler hot zone to maximum with creating positive pressure in the kiln hood.



Reduce primary airflow to control the temperature of the flame

When the sausage disappears and the agglomeration disappears, start to restore the condition of the burning-zone to normal again by: reducing kiln speed and increasing the I.D. fan speed while increasing the fuel rate


How to prevent this phenomenon

The laboratory has to evaluate the possibility to provide mix that have less liquid phase

The operator must be more alert to the condition in the burning-zone

Evaluate the condition of kiln pyrometer installed in the kiln hood and evaluate the flame position and shape to determine if thinner, longer flame is required since the existing flame may be too wide.

Dangerously High Kiln Inlet Temperature 4

Reason for high kiln inlet temp.:

The concentration of sulfur and chlorine in lower most cyclones are very high.

I.D. fan speed sharply increased

Kiln speed decreased and became too low

Lack of materials at kiln inlet due to problems in the kiln feed system or the lower most cyclones are blocked by feed materials and don’t discharge any to the kiln inlet, or the materials are erratically behaving in flushing waves from these cyclones.


Reason for high kiln inlet temp.:

The concentration of sulfur and chlorine may be high in the lower cyclones to the degree that leads to erratic flow of material form these cyclones. This is may be due to either unsuitable by-pass fan speed or due to blocking of by-pass system and/or higher concentration of alkali, chloride and sulfate in the kiln feed

Carbon monoxide exists in kiln exit gas


Consequences of such condition are:

This will make kiln operation increasingly hard with flushes of material coming from these cyclones

The lower most cyclones temperatures increase will lead to blocking of these cyclones by over heated feed material (cake formation)

The inefficient by-pass system or blocked by-pass system, since there may be a drastic increase in the percent of both of chiorine and sulfate in the lower most cyclones.


Consequences of such condition are:

Damage to the kiln inlet area, dust collector and preheater equipment

The fuel can start ignition in the kiln inlet

The kiln will start to be in an upset condition


Reduce fuel rate and I.D. fan speed to obtain less than 1-% oxygen in the kiln inlet but the fuel rate should not be completely cut, since this may trigger an explosion in the kiln electrostatic precipitator.

Increases kiln speed and feed rate

Don’t open any door in the kiln inlet area, so no fresh air will be introduced into the kiln system.




When the temperature of the kiln inlet starts to be normal, Then

Return the kiln operation to normal operation conditions

First start to increase fuel in very slow steps

Start in the same time increasing the I.D. fan speed in the same slow steps

Check the kiln inlet area, especially the gas analyzer equipment


How to prevent such condition from occurring

The kiln must not be operated without feed for more than 10 minutes

Kiln operator must look routinely to the trends or curves of the different instruments monitoring the condition of the kiln inlet area.

The performance of measuring devices in the kiln inlet should be periodically examined.


How to prevent such condition from occurring

During upset conditions, start up and shutdown time, kiln operator should give more attention to the conditions of combustion of the fuel, main burner performance, feed rate flow condition, feed system performance, kiln inlet temperature, I.D. fan speed and how much it is suitable for prevailing kiln conditions

Keep the by-pass system in good operation condition with suitable fan speed

5

When the kiln-burning zone suffers from onrush of partially burned raw feed, the following will take place:

Unburned Raw Materials in the Kiln Outlet or in the Coolers

Black feed area under the main burner flame is

greatly advanced in the direction of the kiln nose

ring area.

The burning zone is blacked-out

When the kiln hood area become black and dusty

Red grate in cooler and the temperature of the

grates will become increasingly high

5

When the kiln-burning zone suffers from onrush of partially burned raw feed, the following will take place:


Rapid increase in the temperature of the material

discharged from the cooler

Decrease of secondary air and tertiary air temperature

Cooler drag-chain for transporting of under grate

dust and spillage will be either over loaded or amp

very high.

5

Reasons behind this phenomenon are :


One or more of lower most cyclones filled up with

materials and suddenly released, while the kiln was

on a maximum speed.

The breaking of ring formation and the trapped

material before it are suddenly released.

When there are bad kiln operation practices or bad

operator behavior, the feed flow to the kiln may be

so erratic to the degree that can cause such condition

5

Consequences of such conditions :


Damage to the cooler components and internal parts may take place with very bad

results such as damage to the driving units or bearing damage for the movable parts.

Flame will disappear or completely extinguished in the burning-zone.

Temperature in the clinker conveying system will be in some instance dangerously

high with eventual damage to this system on the long run.

This condition in the kiln may indirectly lead to excessive heating of the kiln-

burning zone. Since impaired visibility of the burning-zone may make the operator

try to clear it, by heating it up in the way that leads to overheating of this area in the

kiln.

5 Different actions that should be taken during this condition are :

Stop kiln feed.

Immediately stop the kiln and turn it on the auxiliary drive or

minimum speed according to the gravity of the situation.

Start to reduce kiln main burner, and I.D. fan speed according

to the normal practices and slowdown procedure to keep the

kiln inlet temperature under-control.

Reduce the speed of cooler different drives to cope with the new

situation, and switch to manual control, to control the

temperature of the materials in the cooler to cool down.

Adjust cooler airflow to obtain maximum cooling from the

cooler without creating positive pressure in the kiln hood.

Inspect the cooler under grate if possible before start up the kiln

again.

Start to heat up the kiln in the normal procedure until you have

the proper condition in the kiln different parts.

5 How to prevent Such Condition:

Inspect the situation and look for indication that

you are over-feeding the kiln

The burner is not giving the proper amount of fuel

to the maximum feed the operator will give to the

kiln.

In the same time put into consideration the speed

at maximum feed.

5 How to prevent Such Condition:

This study should also look for the situation of the

grate cooler especially for the temperature of the

tertiary air and the secondary air temperatures.

This will, in the end, give clear idea about how to

achieve kiln operation stability in relation to these

conditions previously mentioned.

The operator behavior should be continuously

followed and he should be advised to make frequent

visual inspection of the burning-zone in order to be

able to learn how to detect any sign of an impending

problem related to such formerly explained case

Main Burner Flame Is Distorted 6

Reason for such condition

When the kiln burner is not well adjusted or the

mechanical parts are not in proper conditions.

When the electrical instruments of the kiln main

burner may cause faulty control of the burner.

When the burner tip part is blocked by oil fuel and

dust or it is damaged

When the burner pipe bottom is worn out due to

falling of protective castable and primary air is

escaping from this opining in the bottom of burner

pipe


That can be indicated by the following phenomena

Irregular flame shape and unusual flame shape

Flame is fragmented in a way that will permit for

part of the flame to impinge on lining. This takes

place, especially in the area of burning zone nearer

to cooling zone in the kiln outlet.


Possible Consequences:

Thermal damage to kiln burning-zone, kiln shell and

kiln hood refractory and kiln mantel door especially

if backfire happens in the kiln burning-zone during

this period.

Possible red spots on kiln shell, if this phenomenon is

disregarded and neglected.

Thermal damage to nose ring segments


Action To Be Taken:

Inspect burner pipe for damage especially in the bottom

area where the secondary air loaded with dust from

cooler will hit the pipe in great speed.

If the burner flame is so distorted that is greatly impinge

on the lining of the burning zone i.e. bricks, the kiln

should be shutdown immediately.

If the burner condition can permit for adjusting it during

operation without danger of aggravating the burner

condition, then the burner must be adjusted in way to

provide for smooth operation until a scheduled

shutdown is decided to repair the burner pipe.


How To Avoid Such Case:

During any regular kiln shutdown, burner pipe must be

inspected and repaired in the best possible way. The

price of neglecting the burner pipe or to economize in

the spare parts will be lost production or lost kiln linings

and the final result will be again lost production.

Try to provide the best protection for the burner pipe.

Burner pipe is one of the most troublesome parts of the

kiln section that can give hard job for the kiln manager

if he neglects the process of casting it. Buy the best

castables and anchor available for the burner pipe.


How To Avoid Such Case:

Investigate the process of casting the burner pipe and

the techniques used in this process.

The primary air fan must be programmed in a way that

provide for its operation at least two hours after the

burner is stopped.

Never pull out the burner pipe after kiln shut down, but

continue with the primary air fan for cooling and don’t

take out the burner pipe from kiln hood before four hour

after kiln shut down to protect the castable on the pipe

from taking unnecessary thermal shock.

Failure of Precalciner Burners 7

Reason for Such Case

Interlock with the uppermost (top) cyclones temperature. In order to protect the I.D. fan impeller and shaft from overheating, this interlock is activated in the kiln system.

The gas temperature of the precalciner vessel rises to > 1000ºC. The gas temperature of lower most cyclones that receive gas and materials from the precalciner rises to >1000ºC.

The gas temperature of the precalciner vessel rises to >1000C

The gas temperature of lower most cyclones that receive gas and materials from the precalciner rises to >1000ºC.


Reason for Such Case


The temperature of the fuel decreases less than 65C.

If the kiln feed system is stopped for any reasons mechanical electrical or extraction problem.


During Kiln Shutdown, the following area should be taken care of:


Kiln Feed System

Kiln fuel station and heating system

Burners valve trains

kiln emergency ys

Documents

kiln outlet

eventual kiln

kiln operator

rotary cement kiln

loss of kiln feed

kiln shell refractory

kiln preheater cyclones

upper transition zone