FR2778735A1 - Furnace lining repairing method - Google Patents

Abstract

The method of repairing a furnace lining involves removing the existing lining without damage to the casing (3) and forming a new lining (2) in concrete by spraying. Prefabricated liners (5) are positioned in the casing and concrete poured into the gap between them and the sprayed surface.

Description

The present invention relates to the field of repair or

rehabilitation of

  masonry, and more particularly internal masonry of lime kilns.

  Indeed, in use, lime kilns deteriorate. Two solutions are then possible: - either the dismantling and the destruction of the oven then the reconstitution of a new one, - either the renovation or the repair. This second solution is obviously much less expensive than the first and is used

as often as possible.

  Frequently, the exterior masonry in the oven, most of the time made of refractory bricks, is still in very good condition, while the interior masonry, generally made of concrete,

  has deteriorated a lot with use.

  It is therefore frequent to carry out the rehabilitation of the internal masonry of a lime kiln

  approximately cylindrical, vertical.

  There are already methods of rehabilitating the internal masonry of a lime kiln traditionally, it is first necessary to remove all the internal wall damaged by use, accompanied by residues such as coke, lime, then then develop a new wall

internal concrete.

  Until now, the new internal wall was made by spraying concrete against the

  internal face of the external wall of the furnace according to the so-called "gunning" method.

  The disadvantages of this method are, on the one hand that the spraying of concrete does not make it possible to obtain a very good quality concrete having good mechanical strength and good thermal resistance, and, on the other hand, that this spraying is long and tedious and above all it

  requires a very long drying time, delaying the return to service of the lime kiln.

  In addition, until now, the operation of removing the internal wall was done using a percussion device of the jackhammer type. This had the effect of weakening, without

  this necessarily appears to the naked eye, the outer wall of refractory material.

  The present invention intends to remedy all of these drawbacks by proposing a method and a device implementing this method making it possible to save a great deal of time.

  compared to traditional methods, and achieve better quality rehabilitation.

  For this, the method according to the invention recommends sealing off the cracks and gaps appearing on the internal face of the external wall, in the traditional way, by projecting a

  concrete thickness, but on a sufficient thickness.

  The process then recommends using prefabricated concrete crowns, and

  position in the axis of the oven to reconstitute the inner face of the inner wall.

  The process then proposes to pour concrete between the crowns thus positioned and the

  inner face of the outer wall.

  Thus, not only does the internal wall have very good technical characteristics such as low coefficient of expansion, low thermal conductivity, high resistance to compression and to bending in hot as in cold, high resistance to abrasion, etc ... , but in addition, the furnace can be put back into service more quickly because the precast concrete has already been yes or parboiled and is already dry when it is put in place. On the other hand, the method according to the invention recommends not removing the internal wall with a percussion device, but with a tool with rotating tools, so as not to damage the wall.

  outside. The latter method is also faster than the previous one.

  Finally, still with a view to saving time in order to allow the oven to be put back into service as quickly as possible, the method according to the invention recommends using, to operate the repair of the internal wall, not a suspended basket as we usually do it, but a

  circular spider floor, on which we come to assemble a work floor.

  Indeed, the parallelepiped configuration of the nacelle and very inconvenient to operate in a cylindrical volume, it is therefore preferable to bring inside the oven, from the bottom or from the top, a spider floor made of a metallic structure folded up, hoist this spider floor at the top of the oven, deploy it there, fix a work floor on it, and hoist or lower it all using ropes or cables attached to a winch system according to needs as and when

measure of progress of works.

  Other advantages will emerge from the description given below of the invention, purely by way of

  explanatory, with reference to the appended figures: FIG. 1 illustrates a general view in longitudinal section of a lime kiln, FIG. 2 illustrates a view in longitudinal section of the wall of a rehabilitated lime kiln according to the invention , - Figure 3 illustrates a perspective view of the tool of the tool rotating tool, - Figures 4 and 5 illustrate the spider floor respectively seen from above and seen from the front, and

  - Figures 6 and 7 illustrate the work floor respectively seen from above and front view.

  The method according to the invention is a method of rehabilitating the internal masonry of a

  approximately cylindrical, vertical lime kiln as illustrated in figure 1.

  This rehabilitation of the internal masonry of the lime kiln (1) consists on the one hand of the elimination of the internal wall (2) of said furnace (1) made up of coke, lime and residues without damaging the external wall (3 ) of said furnace (1), generally made of refractory bricks, and, on the other hand, into the development of a new internal wall (2) of concrete by spraying a layer of concrete

  (4) against the internal face of the external wall (3).

  The method according to the invention is characterized in that, for the preparation of this new internal wall (2), inside the oven, in the axis of the oven, there are prefabricated concrete rings (5) having a internal diameter corresponding to the diameter necessary for the proper functioning of the furnace and close to that of a new lime kiln, then in that a thickness of concrete (6) is poured between said precast concrete crowns (5) and said layer of

  shotcrete (4) as illustrated in figure 2.

  The use of these crowns (5) therefore avoids the use of traditional formwork.

  On the other hand, the precast concrete thus placed has qualities identical to those that

  can be obtained in the workshop, while such qualities are difficult to obtain in situ.

  Finally, the prefabricated tenon and mortise elements being raised to at least 100 C, the drying time on the site is greatly reduced, and the oven can be put back into service more quickly. The method also makes it possible to save material compared to the methods by

  projection of concrete called "gunitage" and causes less soiling.

  To ensure better technical characteristics of the materials, it is preferable to pour a thickness of concrete (6) between said precast concrete crowns (3) and the thickness of concrete (4) projected against the internal face of the external wall. (3) between each positioning

  a new prefabricated crown (5) complete in the axis of the oven.

  This thickness of poured concrete (6) can be considered as a second layer

  wear, with an average thickness of about 20 cm, constituting a real layer of security.

  The method according to the invention recommends, for the elimination of the internal wall, to use a tool

  rotary (7) as illustrated in figure 3.

  This rotary tool (7) can be arranged for example at the end of a handling arm

pivotally mounted on a vehicle.

  The vehicle can be brought in from the top or the bottom of the oven. The rotary tool (7) is of the type

milling, trimming or planing machine.

  The rotary tool (7) is of the milling or trimming type.

  The device according to the invention is also characterized in that, for the elimination of the internal wall (2), there is inside the oven (1) a circular metallic structure (8) called "spider floor" illustrated in figures 4 and 5 of diameter smaller than the smallest diameter of the oven, on which is

  assembled a work floor (9) illustrated in Figures 6 and 7.

  To set up the circular structure (8) inside the oven (1), it is best to start by lowering several movement cables from the top of the oven, then, once the spider floor is placed at the bottom of the oven, join the support cables (10) from the spider floor

  with the movement cables previously installed.

  When the support cables (10) are tight, you can start to assemble the floor

  working (9) on the spider floor.

  Safety standards require that the proper installation is checked by a

accredited organization.

  Said circular structure (8) on which the work floor (9) is assembled is movable along the axis of the lime kiln (1) thanks to the movement cables connected to a winch system known per se which makes it possible to vary the height of the complete device composed of the circular structure (8), (the

  spider floor) and work floor (9).

  The device composed of the metal structure (8) on which the floor of the

  work (9) is therefore also mobile along the axis of the lime kiln (1).

  The work floor (9) preferably comprises a railing (11) and a large hatch (13) in its center which allows access to the underside of the structure, to bring the rotary tool and its vehicle

  on the work floor. The work floor is also maintained by support cables.

  This structure also makes it possible to very quickly make a very precise geometric reading of the interior of the furnace before and after the operation of lining the furnace with refractory.

  The gunite layer (4), that is to say sprayed, has an average thickness of approximately 2 cm.

  The prefabricated crowns (5) are composed of elements having dimensions such that the volume and the weight of the blocks allow their handling and their introduction inside the furnace. According to a version of the invention, the upper part (12) of the oven (1) does not contain

D prefabricated crowns (5).

  The method according to the invention is also applicable to the rehabilitation of internal masonry

  of cylindrical or other section silos.

  On the other hand, the different concretes used do not necessarily have the same

technical characteristics.

Claims (8)

  1. Method for rehabilitating the internal masonry of a lime kiln (1), consisting in eliminating the internal wall (2) of the furnace without damaging the external wall (3) of said furnace, and in developing '' a new internal wall (2) of concrete by spraying a thickness of concrete (4) against the internal face of the external wall (3), characterized in that, for the production of this new internal wall (2) , there are prefabricated concrete crowns (5) inside said furnace (1), then in that a thickness of concrete (6) is poured between said precast concrete crowns (5) and the thickness of concrete (4) sprayed against the internal face of the external wall (3). 2. Method for rehabilitating the internal masonry of a lime kiln (1) according to claim 1, characterized in that a thickness of concrete (6) is poured between said precast concrete crowns (5) and the thickness of concrete (4) projected against the internal face of the external wall (3) between each positioning of a new complete concrete crown   prefabricated (5) in the axis of the oven (1). 3. Method for rehabilitating the internal masonry of a lime kiln (1) according to any one of claims 1 or 2, characterized in that the elimination of the internal wall (2) is   made using a rotary tool (7).   4. Method for rehabilitating the internal masonry of a lime kiln (1) according to any one of claims 1 to 3, characterized in that there is inside the furnace (1) a   circular structure (8) on which a work floor (9) is assembled. 5. Method for rehabilitating the internal masonry of a lime kiln (1) according to the   claim 4, characterized in that said circular structure (8) on which the work floor (9) is assembled is movable along the axis of the lime kiln (1).   6. Method for rehabilitating the internal masonry of a lime kiln (1) according to any one of claims 1 to 5, characterized in that the upper part (12) of the oven (1) does not   has no precast concrete crowns (5) .25 7. Device for rehabilitating the internal masonry of a lime kiln (1) implementing the method according to any one of claims 1 to 6, characterized in that it   comprises a circular metallic structure (8) on which a work floor (9) is assembled and in that said work floor (9) is movable along the axis of the lime kiln (1). 8. Lime kiln (1) whose internal masonry is rehabilitated by the process according to one   any of claims 1 to 6.