KILN ALIGNMENT & ROLLER GRINDING

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KILN ALIGNMENT  & ROLLER GRINDING

1.       Hot kiln alignment using electronic devices

 

This technique is applied during rotation of the kiln without the need to stop it. It is considered one of the most modern techniques in this field.

 

1.1     Advantages of this Technique

  1. Reducing kiln stoppage time whereas older techniques require total stoppage of the kiln.
  2. Faster acquisition of results by using a programmed computer for this purpose.
  3. Acquisition of coordinates of the center of the kiln at each base, hence, it is possible to undergo essential adjustments.
  4. After accomplishing essential adjustment operations, it is possible to quickly repeat measurements.
  5. Accurate measurements are achieved as it depends on sophisticated electronic devices and not on manual operations.

 

1.2     Tools and Instruments Used

  1. Prisms are placed in various places as reference points.
  2. Total station equipped with a transmitter and receiver to measure angles and distances.
  3. PC with the basic information installed.
  4. Targets to be placed on rollers (fig. 1).

 

It is well known that accurate measurements of rotary kiln alignment is a main task in measurement and adjustment operations in order to assure trouble-free operation. Therefore, the proper positioning of tyres and rollers, the relations between them and the interference between the large and the small gears facilitate proper kiln operation without any problems.

 

The dislocation of the center of the kiln from the right position due to the dislocation of the rollers can lead to damaging mechanical parts in addition to great production losses. This occurs due to the following reasons:

  1. Depression of the concrete bases of the kiln.
  2. Uneven wear of tyres and rollers.
  3. Incorrect positioning of the rollers at installation.

 

The device we are concerned about here is extremely accurate because it is an electronic measuring device that can measure three dimensional coordinates for a certain point. This system is composed of an electronic device that is used by scanners to determine distances, a programmed computer, prisms, a Circumferential Measuring Device (CMD) and other assistances.

It is also possible to measure angles using the electronic scanning device depending on electronic scanning of digital circular glass lenses. The accuracy of the device is 1 mm for measuring a distance of 100 m.

 

There is a control program that guides the user in order to eliminate any error that occurs directly on the device and all of these tools and instruments are designed to work without electric sources so it can be charged before usage.

 

1.3     Measurement Procedures Using Total Station

(Steps 1-5 fig. 2)

 

1.3.1  Prepare and organize tools, instruments and devices necessary for measurement operation.

1.3.2  Establish a coordinate system to which all designated points are related to.

1.3.3  Fix 360° prisms in various places to connect different designation points as well as fixing targets on rollers.

1.3.4  Measure special coordinates for targets and prisms.

1.3.5  Exchange the position of the total station by reverse measurement operation for the pre-designated prisms and accordingly determine the coordinates of the total station relative to the established coordinate system.

1.3.6  Measuring diameters of rollers and tyres is extremely essential for all the points needed to measure the kiln. They are measured using a Circumferential Measuring Device (CMD) (fig. 3) and will be illustrated later.

1.3.7  Transfer this data to a computer to take it into consideration in addition to considering temperature because this data are useful in making the alignment approach the correct position with high degree of accuracy.

1.4     General Notes

  • Prisms have to be firmly fixed in order to depend on them to transfer coordinates.
  • It is preferable to designate all prisms from the reference point in order to minimize error to a minimum.
  • Some points are designated more than one time in order to overlap which minimizes error.

 

2.       Grinding of rollers & tyres

It is well known that any mistakes in the design, installation or maintenance will directly affect the condition of rollers and tyres where they will be districted or worm, and hence, repair and maintenance will be a must.

And if the kiln will not move up and downhill, more wear will occur at the area of contact between rollers and tyres taking the shape of cavity on the roller or tyre surface (fig 4).

The formation of cavities happens more frequently in the rollers rather than the tyres, this is because of the hardness of the roller surface is lower than that of tyre, however this cavities must be smoothen and polished.

Wear occurs in the rollers as well. And to compensate it, they are moved inward taking into consideration the thickness of metal removed during the grinding process.

 

There are several methods to restore the condition of rollers and tyres depending on the deviation in radius measurements along their width.

If the deviation is between 1 and 3 mm, then the grinding process is the best, but if the deviation is more, then special turning machines (lathes) with special cutting tools should be used, and both methods are performed during the operation of the kiln, and without any interruption to the production.

2.1     Grinding Method

 

The success of grinding process is based on the fine adjustment of the position of the grinding machine on the rollers or tyres.

This can only be done by determining exactly the diameter of the rollers or tyres in many points along their width, so that the suitable skewing (which is based on the values of diameters ) of the center line of the grinding machine translation carriage can be performed to obtain at the end of the grinding process a perfect cylindrical shape with a maximum tolerance in conical of 0.5 mm in radii along the roller or tyre width.

The removal of any ovality in the surface of the rollers or tyres can be guaranteed by using a straight edge on the surface of rollers or tyres, so that the filler blade of 0.2 mm will not pass between this straight edge and the rollers or tyres surfaces along their widths.

To guarantee an efficient operation of the kiln, the contact area between the tyre and rollers should not be less than 75% after the grinding process.

 

2.2     Grinding Machine

 

It is a mechanical device used to grind and clean the surfaces of rollers and tyres and it is shown in (fig 5).

Before using this device, we must ensure that the wear in the station to be ground is within the limits and that the productivity of the kilns is over 80% of the nominal capacity, this is to prevent any more deterioration in its condition.

The grinding machine consists of the following parts:

  • Electrical motor 110-500V – 50/60 Hz.
  • Switch gear.
  • Grinding wheel with transverse motion using geared motor.
  • Mechanical fixation levers and elements.
  • Electrical connections.

According to the specification of the grinding machine, and to the hardness of the surface to be ground, it can remove 0.5 mm in each stroke which takes 2 hours/stroke, depending on the rollers and tyres diameters, taking into consideration the hardness of the cutting tool, where the consumption is between 2 & 3 wheels/day ( based on 24 working hour/day ).

 

2.3     Circumference Measuring Device for Live Rings and Supporting Rollers

2.3.1   General

 

The circumference measuring device is used for measuring live ring and supporting roller diameters (circumference) while the kiln is in operation. These measurements are used to determine the kiln axis on a kiln in operation. In connection with machining of supporting rollers or live rings, the instrument is used for ascertaining any conicity before adjusting the lathe.

2.3.2   Measuring process using the C.M.D. during the kiln operation

2.3.2.1                        Device description

 

The device consists of a wheel ( 150 mm ± 0.0 ) with a spring coupling (1) and an encoder which uses the DC power directly or with backup batteries (2), an infra-red transmitter-receiver (3), infra-red source with optical wave (4), magnetic base to carry the infra-red source (5), magnetic base to be fixed on the side of the tyre or roller to cut the infra-red source (6), optical fiber cable to connect the infra-red source with the counter (7), optical fiber cable to connect the transmitter-receiver of the infra-red with the counter (8), on/off switch for the power supply (9), reset switch of the data on the counter (10), selector switch to select to select the number of revolutions (11), cut-off indicators with reset switch (12), battery charge indicator (13) and a fixation rod (14) as shown in( figure 7 ).

2.3.2.2                        The principles of the C.M.D.

 

The concept of this device is to determine the number of turns that the device wheel made during one revolution of the measured object ( tyre or roller ), therefore the magnet base (6) must be fixed on the side of the measured object ( tyre or roller ), this magnetic base cut the infra-red one time each revolution of the measured object and hence trigger the counter which start counting exactly at the cutting time, the counter is connected to the wheel whose diameter is already known from the beginning therefore the number of turns of the wheel is determined during one single revolution of the measured object ( tyre or roller ). This is done using an electronic pulse transmitter and according the cut off is known directly by the counter.

 

2.3.2.3                        Preparing to measure

  • Connect the cables to measuring unit specially the cables no. 7,8 according to the tags written on the cables ends and the measuring unit.
  • Fix the source of infra-red on the magnetic base by the fixation bolts and the rod over the magnet where it is easy to adjust the infra-red source at any desired direction.
  • Make sure the power supply is connected and the batteries are charged.

The measuring device can be connected directly to the power supply using a special cable or using the batteries which can be charged, the first method is used if the measuring process is carried out near a power supply source while the second is used if there is no power supply is available, and in this case the batteries must be charged one day before.

2.3.2.4                        Measuring steps

  • Before the fixation of the magnetic base (7) on the measured object (tyre or roller) we must make sure that this base is not adjacent to the rollers or the temperature shields since any improper fixation of this base will result in incorrect results and the destruction of the magnetic base where it will be broken if jammed between the tyre and roller as shown in figure (8).

  • Fixation of the measuring wheel as following:
    1. The best way to fix the wheel is over the temperature shields or an a fixed frame over the supporting rollers shields or on the bearing adjusting screws covers or to fabricate special supporting frames for the purpose.
    2. Adjusting the required pressure on the measuring wheel; the measuring wheel must be pressurized against the measured object (tyre or roller ) using the tightening rod. And the leaf spring, when the measuring wheel touches the measured object it starts turning with it and the amount of pressure is determined by 2 teeth of the tightening lever.
    3. Adjusting the concentricity of the measuring wheel, the measuring wheel must be perpendicular on the circumference of the measured object to avoid any mistakes that may happen due to the improper rotation of the measuring wheel.
    4. Taking away the measuring wheel after performing the measurement. Before moving the measure unit away of the object to be measured ( tyre or roller ), this is done by releasing the pressure of the measuring wheel and pull it back using the fixation rod on the tightening lever
  • Operation of the electronic counter:
  1. The unit is operating by turning on the power switch.
  2. Resetting the counter to the operation mode the main reset switch or by individual switch for each counter to increase the life times of batteries the device is turned off automatically if not used.
  3. ( Measuring ) after connecting all the required cables, the counter stands the count after cutting the source of the infra-red by the magnetic base fixed on the side of the measured object ( tyre or roller ), the first counter stops counting after the first turn and the second counter starts immediately. The reading of the first counter is that of the diameter directly, and this reading of the second counter is taken exactly as done for the first counter, this process can be repeated according to the required number of revolutions for the measured object which is determined by the revolution number selection no (11) where we can select (2,4,8) the third counter gives us the average of the diameter during the number of revolutions. The accuracy of this device is 0.1 mm when measuring diameter of 6000mm.

2.3.2.5                        General remarks when using the C.M.D.

  1. The device temperature should not exceed 50°c and not less than -20°c.
  2. To obtain accurate results, the measuring wheel must measure clean an smooth surface of the measured object ( tyre and roller ).
  3. The position of fixing the measuring wheel is selected as shown in the figure when measuring the tyres diameter and at the same angle regardless the direction of rotation when measuring the rollers diameters

 

 

  • Recording the measurements results:
  1. Prepare the table shown below
  2. Write down the obtained results in the table.
  3. Take into consideration that these measurements are taken at high temperature in case of comparison.
  4. From the above measurements the wear in the tyres and rollers can be known and hence the settlement in kiln center line of rotation is determined.

 

4- Fees and Prices

Measurement report only : 3000 USD including air tickets.

to order please contact : info@cementequipment.org

Comprehensive Kiln Inspection survey including final report. For kiln with 3 supports.

The job will be carried out by 2 Infinity for cement equipment kiln specialists.

Fixed price includes:

– Preparation

– Hire of measuring equipment

– Up to 5 working days at site

– Travel days

– Living allowances

For Measuring and correcting service : 24,367 USD

to order please contact : info@cementequipment.org

work will include :

1Rotary Kiln Hot Alignment Measurements:

  • Measuring the supporting rollers and tires diameters in the hot condition
  • Determining the equipment axis of rotation deviation in both the horizontal and vertical plane in the hot condition.
  • Measuring the supporting rollers centre distances.
  • Measuring the supporting rollers slopes.
  • Measuring the girth gear and pinion meshing in the hot condition (This will require a short shut down (8 hours))
  • Measuring the Equipment tires migration and the top gap in the hot condition.
  • Determining the equipment supporting rollers movements required to correct the centre of rotation in the hot condition.

Supervision the correction of the rotary kiln axis of rotation, and axial thrust

  • The correction will be performed during the Equipment normal operation by moving the supporting rollers bearings to their correct positions.

Proper skewing will be also applied to the supporting rollers bearings to adjust the axial thrust.

This process will result in minimizing the mechanical stresses on the shell and the supporting rollers bearings, and the smooth up and downhill motion of the equipment

 Rotary kiln tires and supporting rollers grinding

  • Grinding the supporting rollers and tires surfaces to restore their cylindrical shapes. After grinding the deviation in taper will be less than 0.5mm and the straightness less than 0.2mm between the ground surface and straight edge.
  • Supervision of compensating the reduction in diameters due to grinding process by supporting rollers movements to keep the existing correct axis of rotation.

Grinding plan includes 6 supporting rollers, 3 tires

  • Rotary Kiln Shell & temp. profile Measurements:

The shell and temperature profile will be measured each two meters of the kiln length to detect any shell deformations or any out of limit deviation in the kiln axis of rotation.

NOTE

Maximum removable material by grinding for rollers and tires surface is 6 mm , in case exceeded this value extra fees will be added

Gurantee :

infinity corp. will guarantee  the quality of the Rotary dryer Equipment services  for 9 months provided that the equipments are running under the normal operating conditions. In case that any supporting rollers have been changed by the client, Infinity corp. will readjust the roller position to maintain the drum alignment free of charge

to order please contact : info@cementequipment.org

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