CAPITULO III. ANALISIS
ANEXO 2. Recorrido para primera operacionalización de las variables
12.1 OBJECTIVE AND SCOPE
This procedure, intends to cover whatever is needed when a kiln tube section or kiln shell must be replaced.
12.2 METHOD BASIS OR FOUNDATION
When the kiln tube section or kiln shell must be replaced, this is due first of all to the need of having a good surface for the refractory brick correct placement.
The fault shown by the kiln section or kiln shell requiring its replacement, is normally due to a permanent or thermal deformation in the kiln tube, causing additionally damages in the bricks as mentioned, showing irregular overloads in the support rollers.
12.3 METHOD DEVELOPMENT
12.3.1 Equipment and tools to be used 12.3. 1.1 Equipment and tools
- Portable oxyacetylene cutter, with all its implements, such as rails or guides, blowtorch or gun, etc.
- Welding equipment, with its fittings.
- Alignment sevens or irons or jacks or pins (see Figure 12.1)
- Mounting angles or angular consoles with their adjustment screws (see Figure 12.1) - Micrometer, with its magnet carrier.
- Punch.
Aproximate number of adjustment
irons Pins
Number Diameter Kiln
(m)
1) Tensioning pins 2) Mounting irons 3) Adjustment irons
12.3.1.2. Support equipment - Ultrasound equipment.
- Support beams, to support the kiln shell, they could be railroad mudsills, etc.
- Crane to perform maneuvering, capable to support the kiln shells.
12.3.1.3 Work materials - Welding application 12.3.1.4.Supporting materials
- Kiln position plan or drawing
- Plan or drawing of disposition, holes for internal installations, etc.
12.3.2 Periodicity
The eventuality in the kiln shells or kiln sections replacement, is made whenever so required, due to problems caused by it when being distorted or deformed.
12.3.3 Procedure, calculation methods and results
First the kiln shell or kiln section size or kiln tube section size are determined, manufactured, the damaged kiln shell is removed, and the new one is placed. Now, next are described in more detail the measuring and kiln shell replacement activities.
12.3.3.1 Determination of damaged kiln tube section measure
1.- The kiln shell diameter and length are determined, with special care that this measuring is made when the kiln is in cold environment conditions, and with these dimensions, and supported by the kiln drawing, a kiln shell can be manufactured in accordance to reality. Caution must be observed in the consideration of rivets, pumped welding applications, splice plates, etc.
2.- With the kiln shell or kiln section dimensions, the new kiln shell can be ordered to Manufacturing.
12.3.3.2 New kiln shell manufacturing and handling
The kiln shell is ordered for manufacturing according to the material and thickness specifications indicated in the manufacturer drawing. '
It must be inspected when being received, by measuring the diameter at the ends through a rule assuring it is perfectly circular, and provided with a reinforcement cross, in order to prevent its damage during the transportation and handling. If the kiln shell is thick (higher than 2.85 m.), it must have an extra cross placed in the middle point.
It is recommended to leave the reinforcement cross on its place in the kiln shell, until the moment when it is joined by angles and pins (or alignment pins) with the adjacent kiln shell. As soon as the pins (or jacks) for kiln shells union, and once the joint is centered through the adjustment irons, the reinforcement crosses can be cut, or can be left until after the first bottom cord¡.
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shoring crosses joists are cut before proceeding to the kiln shells union. Jacks or tensioning pins must be utilized to make the kiln shell return to its circular form. If this work is made during the mounting operation, exclusively tensioning pins are utilized.
The shoring crosses situated in the middle point of a thick kiln shell, must not be removed until finishing its total mounting and welding operations.
When the kiln shell is to be utilized, the chamfers provided for the welding joints must be perfectly clean.
All the paint, when burned produces gases and reduces the welding application quality must be removed.
12.3.3.2 Preparation steps
Previous to proceed with the kiln shell removal, and the new kiln shell placement, it is necessary to examine:
a) The possibilities to transport the pieces, before and during the kiln shell removal, and the new kiln shell mounting.
b) The elevation devices available, such as cranes, hydraulic jacks, etc.
c) The possibilities to spin the kiln during the alignment and welding operations. It is recommended to perform spins with the slow spinning device, and in case of utilizing tackles or hoisting machines, observe that the traction is upwards in order to reduce the supports friction.
12.3.3.3 Damaged kiln shell removal, and surfaces preparation
1.- In a convenient extension around the repair place the material, the refractory and the internal installations are removed.
2.- Spinning the kiln, supporting against just one of the guide roller (or candlestick), lines are traced on the kiln shell corresponding exactly to the new kiln length. 100 mm away from each side of these lines, two reference lines are traced, see Figure 12.2. The reference lines are provided with punch marks. Identify at the same time, if a kiln shell warping correction is needed.
3.- The kiln tube is supported as illustrated in the beginning in Figure 12.2, and the kiln shell is cut with the automatic oxyacetylene cutting equipment, and the kiln shell is dismounted.
4.- The kiln tube cut edges are chamfered such as indicated in Figure 12.3.
5.- In case the kiln shell being changed, contains a kiln tire (or tire), this is the time to perform its change, from the old or damaged kiln shell to the new one.
12.3.3.3 New kiln shell mounting
1.- The new kiln shell is placed in its site, and besides the cut in the kiln tube nearest to the entrance, mounting angles are welded, as many as depending on the kiln shell diameter and length.
Normally the adjustment irons are welded in the kiln shells internal wall, with limitation to the number of irons absolutely necessary, see Figure 12.1.
3.- Internally and externally in the bottom (or lower part) and above (or upper part) of the kiln shell, respectively, a welding cord of 800 - 1 000 length is welded. Internally the complete joint is welded and externally a cord with the same dimensions must be applied, so that, both cords have the same section, in attention to a uniform contraction.
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Internal side
Figure 12.2
Figure 12.3
Control Measurement
Control Measurement
Figure 12.4
cord with appropriate length can be applied.
5.- Once the joint half is externally and internally finished, the kiln shell alignment must be controlled.
In case the alignment is incorrect, it must be corrected by cutting, beveling and welding part of the circular joint welded. If in the previous work the reference line measuring has been confirmed and if the welding application has been executed with equal sections of the internal and external cords, the kiln shell must be centered.
6.- The bottom cord is chiseled, and the joints are finished.
7.- The upper part (towards the entrance) of kiln is mounted and welded in form analogous to the explained in the above:
12.3.4 Interpretation of results
The results under this procedure must be positive, and a kiln tube perfectly aligned and in running conditions will be available. Each moment the whole kiln tube circumference perfection must be checked with a rectilinear rule.
12.3.5 Safety aspects
It is always dangerous to work close to a rotary kiln. To measure and control the parallelism and flotation of the kiln rollers is required to work very close to it; appropriate clothing, safety goggles, safety shoes, gloves and safety shell must be utilized.
12.3.6 Condemning or permissible limits
The maximum kiln tube alignment deviation allowed is +/- 1.5 mm.
12.4 COMMENTS AND OBSERVATIONS
The development of distorted kiln section or kiln shell replacement activity, is a job requiring persons with long experience, thereby they must be consulted as necessary when performing this procedure.
12.5 ATTACHMENTS AND FORMS UTILIZED
No attachments are included, and the forms to be used are free.
12.6 REFERENCES
- Heavy kiln shell substitution, Manual, Instructive F. L. Smidth 11.124 (2) - Mounting of kiln tube and kiln tires, Manual F. L. S. 18094-07