EP1093560B1 - Ring type furnace - Google Patents

Description

Field of the invention

The invention relates to revolving furnace chambers used for cooking blocks carbonaceous, and more particularly open type furnaces.

State of the art

Open type rotating chamber furnaces are well known in themselves and described in particular in patent applications FR 2 600 152 (corresponding to the patent US 4,859,175) and WO 91/19147. In these ovens, a gas flow consisting air and / or combustion gases circulate in the succession of active chambers in the long direction of the oven, in a succession of hollow heating partitions which communicate with each other from one room to another, each room being made up of the juxtaposition in the cross direction of the oven, alternately, of these heating partitions and cells in which the carbon blocks to be cooked are stacked. This gas flow is blown upstream of the active chambers and is sucked downstream of these chambers.

A hollow room partition typically takes the form of a rectangular parallelepiped 5 m long (long direction of the oven), 5 m high and 0.5 m wide (across the furnace) or 0.3 m of gas stream and twice 0.1 m wall), subdivided into 4 vertical "wells" thanks to 3 vertical baffles arranged in the cross direction, each well being bounded either by two baffles, or by a baffle and a of the walls of the room, so as to increase the average air path of cooling or combustion gases in said partition and, in addition, to ensure a constant spacing between the longitudinal walls of the partition.

In addition to the baffles, spacers are also arranged in the cross direction, in particular between said baffles, to ensure constant spacing between the walls longitudinal of the partition.

Problem

A constant concern of the manufacturer of baked carbon blocks is - quality constant - to decrease the production costs of these cooked carbon blocks and the costs investment and / or maintenance of the ovens used to manufacture them, particularly in increasing the service life of the refractory elements of the ovens.

Another concern is to improve the quality of these cooked carbon blocks, by particular to improve consistency of quality and consistency of performance within from the same carbon block and from one block to another.

To this end, the applicant has had the idea of modeling the circulation of gaseous fluids in existing oven partitions, knowing the dimensions and locations of the baffles and spacers.

On the one hand, she was surprised to find that, in hollow partitions according to the state of art, the distribution of the gas flow was far from homogeneous and uniform, so that, in steady state, most of the gas flow or flow flowed according to preferential paths, leaving a non-negligible part of the walls of the partition without contact with said gas flow. However, these walls separate the carbon blocks from the cells of said heating or cooling gas flow and ensure the heat exchange between gas flow and carbon blocks. It is therefore easier to understand that this heterogeneity thermal walls can either result in a variable quality of carbon blocks, or require - which is in practice the case - an increase in heating power or cooling so that even the blocks placed in an unfavorable position in terms of heat exchange, can meet the required quality requirements.

On the other hand, the modeling also highlighted the significant pressure drop in the flow gas due to the presence of baffles, which has the double consequence on the one hand increase the energy required to circulate the gas flow in the succession of partitions, and on the other hand to increase the corresponding overpressure or depression in said partitions, which leads to an increase in thermal leaks in a one way or the other (from said partition to the outside or from the outside to said partition), and therefore the energy consumed.

In addition, as the partitions are frequently subject to large deviations from temperature and deteriorate as a result although they are made in refractory bricks, they must be replaced periodically. The plaintiff has therefore also sought ways to have a more economical oven, not only in operating cost, but also in maintenance or investment cost.

Finally, she tried to devise means to solve these problems (distribution of heterogeneous gas flow within the partitions, ...), not only so as to design new ovens not having the disadvantages of known ovens, but still and especially so as to be able to adapt and modify existing old ovens, and obtain more economical ovens in both operating and maintenance costs. Given the validity of the modeling recognized by the plaintiff, and the difficulty and very high cost of any experiment with real ovens, the Applicant sought the solution to the problem posed using these same modeling instruments which have made it possible to discover the origin of the problems solve.

Description of the invention

According to the invention, the rotary fire oven with open type chambers for cooking carbonaceous blocks comprises, in the long direction X of the furnace, a succession of chambers separated by transverse walls with openings, each of the bedrooms comprising, in the transverse direction Y of the furnace, an alternation of hollow partitions ensuring the circulation of a gaseous flow for heating combustion gases or a gaseous flow cooling air, and cells containing the carbonaceous blocks to be cooked, each said hollow partitions of a chamber being in communication with a partition of a upstream chamber and / or a partition of a downstream chamber, so as to form a duct ensuring the circulation of said gas flow, from upstream to downstream, in the long direction X on all of the simultaneously active chambers for said rotating light, each of said partitions of a chamber comprising, in the X-Z plane, two side walls vertical, and, in the cross direction Y, elements ensuring the deflection of said gas flow traversing said partition and maintaining a constant spacing of said side walls, and is characterized in that each partition comprises means for storing, on a length L equal to at least one third of the length L of said partition and, typically, by an appropriate choice of said elements ensuring said deflection, a gaseous flow of flow D evenly distributed over the entire cross section S of said partition in the Y-Z plane, with a level of homogeneity of said distribution of flow D defined by the expression "2y.D - 0.5y.D / y.S", where "2y.D - 0.5y.D" designates the extent of the range of the flow D corresponding to a fraction y of said cross section S, and where y is at most equal to 0.25.

Compared with the state of the art, the invention is distinguished by the elimination of vertical baffles, generally three in number per hollow partition.

According to the state of the art, if we denote by L the length of the hollow partition in the direction X, by H its height in the direction Z, and if, as a first approximation, we assimilate the height C of baffles in direction Z at height M of walls transverse to ends of said partition, the average path of the gas flow can be broken down into a component in the longitudinal direction X, over a length L, and in a component in the vertical direction Z, over a length 4xC, ie in total L + 4xC.

The values of C and M are typically between 0.6xH and 0.8xH. So with 3 baffles, the gas flow is a tubular flow which changes direction 8 times (X / Z-X / Z-X / Z-X / X), each baffle bringing a change of direction in the vertical direction Z and in the longitudinal direction X noted "Z-X", alternating the longitudinal directions (X) and the vertical directions (Z), the entire gas flow being concentrated, at each passage of baffle, on a straight section S corresponding to a height of 0.2xH-0.4xH, i.e. 20 to 40% of the total section S.

According to the invention, on the other hand, and in the case where the same type of hollow partition is conserved, the average gas flow follows an average trajectory which is, in first approximation and taking into account the absence of vertical baffle, the arithmetic mean of the shortest trajectory, that of length L, and of the longest trajectory, either that of length equal to L + 2xM, i.e. ½ (L + L + 2xM) or L + M, to compare to the trajectory of the state of the art L + 4xC, with C close to M.

Furthermore, typically, by an appropriate choice of said elements ensuring said deflection, the gas flow of flow rate D is distributed homogeneously over the entire section straight line S of said partition in the plane Y-Z, with a level of homogeneity of said distribution of the flow rate D equal to 0.50.D - 0.125.D /0.25.S, said level of homogeneity being noted "2y.D - 0.5y.D / y.S", "2y.D - 0.5y.D" being the range of the fraction of flow D corresponding to a fraction y, with y at most equal to 0.25, of said cross section S, which is equal to the product of the height "H" by the constant width "1" of the partitions hollow.

Taking into account that the deflection elements are oriented in the transverse direction Y and the resulting symmetry, the formula giving the level of homogeneity also applies in the X-Z plane, the section S then being replaced by the height "H", and then being there a fraction of this height H.

Said cross section S being always taken in the plane Y-Z, and the elements ensuring the deflection being in the transverse direction Y, it is therefore possible to represent, by numerical simulation, the distribution of the flow D in the X-Z plane of a hollow partition, as illustrated in Figures 3 and 4 showing sections or sections of ovens or hollow partitions in the X-Z plane.

Modeling of gas flows is carried out from a decomposition of the flow total gaseous in a number N of elementary gaseous threads - for example a fifty nets as illustrated in Figures 3 and 4, and it leads to a visualization of the trajectories of each of these nets in the X-Z plane, and therefore at the distribution of elementary gaseous nets, in the same way of spacing between contour lines on a map From there, it is easy to calculate the level of real homogeneity on any fraction "y" of the height H by counting the number "n" of elementary nets to obtain the n / N fraction corresponding to the height fraction "y" which was set to 0.25.

This choice of 0.25 and the corresponding expression of the level of homogeneity reflects the level of homogeneity found necessary according to the invention to obtain the advantages of the invention. It is obvious, given the law of the mean, that if the value of "y" increases, the level of homogeneity, easier to obtain, is lower. So the level expressed by "0.8D - 0.2D / 0.4.S" corresponds to a lower level of homogeneity than that expressed by "0.5.D - 0.125.D / 0.25.S" to the extent that, plus the fraction "y" is high, the greater the probability that a flux close to y.D is there, the whole of the flow D being by definition present for y = 1. Conversely, the level of homogeneity would increase strongly for a level of homogeneity such as "0.20.D - 0,05.D / 0,10.S "where" y "has a low value, this level of homogeneity not being necessarily accessible over a large portion of length L ', nor necessarily necessary to obtain a significant increase in the advantages according to the invention.

The overall level of homogeneity is therefore expressed in fact by the portion of the surface of hollow wall, in the X-Z plane - or of corresponding volume - where the level homogeneity reaches at least a given threshold set at 0.5.D - 0.125.D / 0.25.S.

According to the invention, on at least one third of this surface, or, which amounts to the same thing, on one third of the length L of said hollow wall, at least said level of homogeneity is achieved.

The means according to the invention make it possible to solve the problem posed. Indeed, from the invention ensures a better distribution of the gas flow, and therefore a greater temperature uniformity, while reducing the pressure drop, which leads in definitive both to a more homogeneous production, to a reduction in operation of the ovens and an increase in the life of the ovens.

Description of the figures

Figures 1, la, 2, 3 and 3a correspond to the ovens according to the state of the art. The Figures 4. 4a, 5. 6 6a, 7a to 7d and 8 correspond to the ovens according to the invention.

Figure 1 is a schematic view, in section along the plane X-Z, X being the direction longitudinal and Z the vertical direction, of the portion of the rotary fire oven (1), active simultaneously on 10 rooms (2), each room being separated from the next by a transverse wall (32) provided with an opening (320) ensuring the circulation of the gas flow flow rate D upstream (on the right in the figure), where air is injected thanks to a ramp blowing (231) provided with as many pipes (230) as there are hollow partitions (3) longitudinal provided with baffles (31) (three baffles per hollow partition and per chamber), downstream (on the left in the figure) where the gas flow is sucked in by means of a ramp (211) with as many suction pipes (210) as there are hollow partitions longitudinal.

Burners (220), positioned substantially in the middle of the series of 10 chambers. bring the upstream gas flow to the desired temperature level, typically of the order 1100 ° C. The chambers located upstream of the burners are cooling of the carbon blocks, while the chambers downstream of the burners are carbon block cooking chambers.

Given the pressure in the oven, as shown in Figure la, a gas flow (233) can exit the oven upstream of the burners, and a gaseous flow of air (213) can enter the oven downstream of the burners. Thus, the gas flow of flow D flowing in said hollow partitions is not a constant flow flow, taking into account both these gas flow (213, 233), and taking into account the formation of combustible volatile products during the cooking of the carbon blocks in the chambers in the downstream part of the oven. The gas flow is an air flow (34) upstream of the burners (220), and is a gas flow of combustion (35) mixed with an incident air flow (213) in the downstream part of the furnace. these flow having a flow, generically designated by "D".

FIG. 1a represents the pressure curve of said gas flow of flow rate D, inside said hollow partitions (3). The pressure decreases regularly from upstream to downstream it is higher than atmospheric pressure and maximum at the blowing of air through pipes (230), it is close to atmospheric pressure just upstream of burners (220), where a pressure sensor (234) is installed, it is lower than the atmospheric and minimum pressure at the intake of combustion gases by the suction pipes (210).

Figure 2 shows a perspective view. partially exploded, from the upstream part of the series of active chambers, making it possible to observe, in the transverse direction Y, for the same chamber (2), the alternation of hollow heating partitions (3) and cells (4) containing the stack of carbon blocks (40). Each hollow partition (3) is limited in the X-Z plane by two vertical walls (38), and contains three baffles (31), is provided with openings (30) into which the blowing pipes (230) can be inserted as shown in the figure, or suction (210), the burner injectors (220), or various means of measurement. To the right of the openings (30) are the wells (38). that is to say the interior space of said partition without obstacle so as to be able introduce the aforementioned devices (blow pipes for example). The bedrooms (2) successive, two of which are shown in the figure, are separated by a wall (32). provided, at the level of said hollow partitions (3), with openings (320) allowing the gas flow from upstream to downstream. in the X'-X direction.

FIG. 3 represents a map of the gas flow, obtained by simulation digital, broken down into fifty elementary threads (6), in a hollow partition according to the state of the art represented in FIG. 3a, provided with 3 baffles (31) and a certain number of spacers (33) maintaining a constant spacing between the walls (38) of said partition. Figure 3a have been shown the length L and the height H of a partition hollow for a given room, the height C of a baffle, and the height M of the wall (32) at each end of the partition.

• une première portion, notée A, de longueur inférieure à L/2, et de préférence inférieure à L/3 comprenant des moyens (entretoises notamment) pour transformer un flux initial de section So en un flux de section S s'étendant sur toute la section creuse et ayant ledit niveau d'homogénéité, grâce à la formation d'une dizaine de fractions de flux (7);
• une seconde portion, notée B, de longueur au moins égale à L/3 et de préférence au moins égale à L/2, où ledit niveau d'homogénéité est partout atteint :

• une troisième portion, notée C, de longueur aussi réduite que possible, où le flux gazeux se reconcentre, ledit niveau d'homogénéité n'est pas atteint car il peut y avoir localement des concentrations de flux qui peuvent se situer hors de la plage 0,50 D et 0.125.D pour une fraction de la section de 0,25.S.

Figures 4 and 4a are similar to Figures 3 and 3a but relate to the invention. It is easy to verify, in FIG. 4, that the level of homogeneity defined by 0.50.D - 0.125.D / 0.25.S is reached over the length L ', between the abscissae X ₁ and X ₂ . We can see, in Figure 4 where the gas flow moves from left to right:

• a first portion, denoted A, of length less than L / 2, and preferably less than L / 3 comprising means (spacers in particular) for transforming an initial flow of section So into a flow of section S extending over the entire hollow section and having said level of homogeneity, thanks to the formation of ten flow fractions (7);
• a second portion, denoted B, of length at least equal to L / 3 and preferably at least equal to L / 2, where said level of homogeneity is everywhere reached:

• a third portion, denoted C, of as short a length as possible, where the gas flow is reconcentrated, said level of homogeneity is not reached because there may be locally concentrations of flow which may be outside the range 0 , 50 D and 0.125.D for a fraction of the section of 0.25.S.

Figure 5, corresponding to a second embodiment of the invention, is a view partial schematic, in section in the X-Z plane, of the gas flow on a meme succession of hollow partitions of simultaneously active chambers for the same fire revolving, in case the rooms are not separated by a transverse wall Le gas flow retains a substantially constant section S over all of its route, a distribution means (232) being used upstream of said rotating light, so as to inject, through transverse slots or openings (2320), a gas flow, in the form of ten flow fractions (7), having said level of homogeneity, a other distribution means (212) being used downstream of said rotating light, so as to sucking said gas flow through transverse slots or openings (2120) without altering said level of homogeneity. Only the gas flows in the hollow partitions at both ends have been shown. The gas flow consists of a set of fractions flow (7), forming a tubular flow (50) substantially oriented along the longitudinal axis X'-X.

Figure 6 corresponds to Figure 1, after modification according to Figure 5, in particular removal of the transverse walls (32), and introduction of the distribution means (212, 232). Were not shown in this figure means for ensuring, at the level of burners (220), uniform heating of said gas flow. Figure 6a, similar to the FIG. 1a represents the static pressure curve of said gas flow, in an oven according to with the state of the art (curve I), and in an oven according to the invention (curve II & III), curve II corresponding to the case where the rooms are separated by walls transverse (32) having an orifice (320) for the passage of the gas flow, while the curve III corresponds to the case of FIGS. 5 and 6 where the gas flow conserves, from upstream to downstream, substantially the same section S.

Figures 7a to 7d illustrate, in section in the X-Z plane, spacers or elements ensuring the deflection of said gas stream, or of gas streams (6) which flow around said spacers (33a, 33b, 33c, 33d), some (33c and 33d) being of oblong shape with a major axis (330), to facilitate the flow of the gas flow and reduce its loss of charge.

FIG. 8 illustrates the case where, in order to further reduce the pressure drop, oblong elements (33c, 33d) are used and oriented, so that the orientation of the major axis (330) of said spacers coincides with the direction of flow gaseous, in particular in the case where said chambers are separated by walls (32) provided with orifices or openings (320) ensuring the passage of said gas flow from a room to another.

Detailed description of the invention

According to a first embodiment of the invention, illustrated in particular in Figures 4 and 4a, said oven (1) comprises chambers separated by a transverse wall (32) having openings of section So (320) ensuring the passage of said gas flow (34, 35) from a partition to the next partition, and in which each partition comprises, at its upstream part, a means for obtaining, from an initial flow of flow D of section So, a flow of section S> So having said level of homogeneity at least equal to 0.50.D - 0.125.D / 0.25.S. According to this modality, said conduit (5) is not of constant section, its section worth So, at each transverse wall (32), and S >> So in each partition hollow itself.

Said means transforms. over a distance less than L / 2, L being the length of said partition, a gas flow with flow D and initial section So at the upstream inlet of said partition, in a flow of section S at least equal to 3.So, and having said level uniformity. Preferably, said distance is less than L / 3. In Figure 4, said medium is on the part marked "A".

Each partition may include, in its upper part, one or more openers (30), which can be closed by a cover (36) and which give access to wells (37).

According to the invention, said means for obtaining said gas flow of flow rate D and of section S having said level of homogeneity consists of dividing elements, or spacers, (33) dividing, in a number of steps varying from 2 to 4, said initial flow of section So, as shown in Figures 4 and 4a, in a dozen flow fractions (7). On the Figure 4a, we can, as an indication, consider 3 steps to divide the initial flow So: the first comprising 2 spacers or elements (330), the second comprising 6 spacers or elements (331), the third comprising 10 spacers or elements (332), these 10 spacers or elements constituting a front downstream of which - to the right of which on the Figure 4a - said level of homogeneity is obtained. The initial flow So is thus divided into 11 flow fractions (7) over the entire section S.

According to another embodiment of the invention, as shown in Figures 5 and 6, said conduit (5) is of constant section, said walls (32) having openings (320) having substantially said section S, in the plane Y-Z, so as to form conduits (5) of substantially constant section S, from upstream to downstream, on all the partitions hollow (3) simultaneously active for said fire, wherein said level of homogeneity is obtained by a removable distribution means (232) introduced, upstream of said light rotating, at the upstream end of said conduit (5), so as to inject into each conduit (5) said gas flow with said level of homogeneity, in the form of ten flow fractions (7) - 8 fractions illustrated in Figure 5.

In addition, it may be advantageous, to maintain said level of homogeneity over the most long possible length of conduit (5) to use a removable distribution means (212) also downstream of said rotating light, at the downstream end of said duct (5) formed by the succession of hollow partitions (3) active for said fire, so as to draw said flow gaseous without disturbing upstream said level of homogeneity of said gas flow.

According to the invention, said distribution means (212. 232) can be an enclosure or a parallelepipedic distribution panel (232), of horizontal flat section, in the X-Y plane, chosen so that said enclosure can be introduced vertically into said well (37) of said partition (3) or between two chambers, and of vertical plane section in the plane Y-Z slightly lower than said section S of said partition in the plane Y-Z, having a face parallel to the Y-Z plane provided with openings (2320) with calculated geometry, either to inject said gas flow, in the form of flow fractions (7), with said level homogeneity upstream of said conduit (5), or to aspirate said gas flow downstream of said conduit (5).

Whatever the method of the invention, said means for preserving a gas flow of flow D having said level of homogeneity on said section S comprises a plurality elements or spacers (33) fixed to said side walls (38) and distributed, in function of the results of the numerical simulation, in a substantially homogeneous the surface of said side walls (38) in the X-Z plane of said partition or said conduit, in sufficient number to ensure said constant spacing of said walls side (38), so as to divide said gas flow into a number of flow fractions (7) varying from 3 to 20 regularly distributed over the whole of said section S, and to be ensured for said fractions a flow with predetermined orientation, possibly according to said long direction X of the furnace, so as to have a substantially tubular flow (50) on all or part of the conduit (5) according to the method of the invention.

According to the first embodiment of the invention, illustrated in FIG. 4, we observe, on all section S, about ten flow fractions (7) in the part marked "B" of length L ' on which said level of homogeneity is reached, each fraction of flow (7) possibly group together several elementary nets (6) shown in solid line in FIG. 4.

As regards the second modality, it has been illustrated diagrammatically in FIG. 5 also with about ten flow fractions (7), although the spacers did not have been indicated in the figure.

It may be advantageous for said elements or braces (33) to be profiled so to reduce the pressure drop of said gas flow, while ensuring the other functions required to maintain a constant spacing between said side walls (38), and to obtain or maintain for said gas flow said predetermined level of homogeneity on said section S.

Figures 7a to 7d illustrate, in section in the XZ plane, different profiles of spacers or elements (33a, 33b, 33c, 33d), some (33c and 33d) being oblong in shape with a major axis (330), for facilitate the penetration of the gas flow and reduce its pressure drop. The pressure drop P will a priori be in the following order: P _33a > P _33b > P _33c and P _33d .

It can also be advantageous, so as to further reduce the pressure drop, to use oblong elements (33c, 33d) and to orient them, as illustrated in Figure 8, so that the orientation of the major axis (330) of said spacers coincides with the direction of the gas flow, in particular in the case where said chambers are separated by walls (32) provided with orifices or openings (320) ensuring the passage said gas flow from one room to another.

Example of realization

We modeled and then built a furnace (1), of the type represented in FIG. 1, and comprising hollow partitions according to FIGS. 4 and 4a of the invention, constructed with bricks and spacers made of refractory material. FIG. 4a constitutes the plan of construction of the hollow partition (3), like a brick wall, the elements hatched extending transversely (direction Y-Y ') over the entire width (0.5 m) of said partition - width which comprises 0.3m of gas stream and 2 x 0.1m thickness of the hollow partition. The scale of Figures 4 and 4a is given by L = 4.178 m, and by the thickness of each brick of refractory material = 91.5 mm.

Prior to the construction of the furnace, the modeling of gas flow flows in the hollow partitions was carried out by dividing the total flow into fifty elementary streams or gaseous nets (6), the representation of a configuration according to the invention obtained by said modeling led to FIG. 4 where the trajectory of each gas stream (6) is shown. Said modeling was carried out using computer means known in themselves.

• la zone A correspond à la formation d'un flux gazeux de section S présentant ledit niveau d'homogénéité, à partir d'un flux gazeux de section So << S,
• la zone B correspond à un écoulement sensiblement tubulaire dudit flux gazeux, qui présente ledit niveau d'homogénéité (avec y = 0,25) sur une longueur L' de la cloison,
• la zone C correspond à la partie où le flux gazeux se reconcentre, passant d'une section S à une section So, au passage du mur entre deux chambres successives.

In FIG. 4, there are 3 zones, marked A, B and C, the gas flow flowing from left to right:

• zone A corresponds to the formation of a gas flow of section S having said level of homogeneity, from a gas flow of section So << S,
• zone B corresponds to a substantially tubular flow of said gas flow, which has said level of homogeneity (with y = 0.25) over a length L ′ of the partition,
• zone C corresponds to the part where the gas flow reconcentrates, passing from a section S to a section So, on passing the wall between two successive chambers.

Advantages of the invention

The oven according to the invention effectively solves the problem posed: whether the consistency of the quality of the carbon blocks, the energy consumption of the oven, or still the life of the furnace, on all these planes, the present invention provides a improvement to existing ovens according to the state of the art.

The energy consumption of the oven is significantly reduced at the same time thanks to a better temperature uniformity, which avoids unnecessary local overheating, and cause of a lower pressure drop (see Figure 6a).

The overall gain, both in terms of the energy consumption of the oven and the consumption of refractories, is at least 10%, which is considerable in this type industry.

Claims (8)

1. Ring furnace (1) with open type sections (2) for baking carbonaceous blocks (40) comprising, along the longitudinal X direction of the furnace, a series of sections (2) separated by headwalls (32) provided with openings (320), each section comprising an alternation of hollow walls (3) along the transverse Y direction of the furnace, through which a heating gas flow (35) consisting of combustion gas or a cooling air flow (34) circulates, alternating with pits (4) containing carbonaceous blocks (40) to be baked, each of the said hollow walls (3) in a section (2) being in communication with a wall in an upstream section and/or a wall in a downstream section, so as to form a conduit (5) through which the said gas flow (34, 35) circulates from the upstream side to the downstream side, in the X longitudinal direction on all sections simultaneously active in the revolving fire of said ring furnace, each of the said walls of a section comprising two vertical lateral partitions (38) in the X-Z plane, and elements in the transverse Y direction for deflecting the said gas flow passing through the said wall and maintaining a constant separation between the said lateral partitions (38), characterized in that each hollow wall (3) comprises a means of maintaining, over at least a third of the length L of said wall, a gas flow D uniformly distributed over the entire straight cross-section S of the said hollow wall (3) in the Y-Z plane, with a degree of uniformity such that the flow in the fraction y with cross-section y.S is between 2y.D and 0.5y.D, regardless of the fraction y of the cross-section considered, and in which y is not more than 0.25, the said means comprising a plurality of elements or tie beams (33) fixed to the said lateral partitions (38) and uniformly distributed in the X-Z plane of the said wall or the said conduit at the surface of the said lateral partitions (38), in a sufficient number to enable the said constant separation of the said lateral partitions (38) so as to divide the said gas flow into a number of flow fractions varying from 3 to 20 uniformly distributed over the entire said cross-section S, and to control a flow with a predetermined orientation for each of the said fractions, possibly along the said X longitudinal direction of the furnace.
2. Furnace according to claim 1, comprising sections separated by a headwall (32) with openings with cross-section So (320) through which the said gas flow (34, 35) passes from one wall to the next wall, and in which the said wall comprises a means in its upstream part for obtaining a flow with cross-section S > So, starting from an initial flow D with cross-section So, with a uniformity such that regardless of the fraction y of the wall considered, the flow in this fraction with cross-section y.S is between 2y.D and 0.5y.D, the value of y being equal to not more than 0.25.
3. Furnace according to claim 2, in which the said means transforms, over a distance equal to half the length L of the said wall, a gas flow D with an initial cross-section So at the upstream entry to the said wall, into a flow with a cross-section S equal to at least 3.So and with the said degree of homogeneity.
4. Furnace according to claim 2, in which the said means of obtaining the said gas flow D with cross-section S and the said degree of homogeneity is composed of dividing elements or tie beams, dividing the said initial flow with cross-section So through a number of steps varying from 2 to 4.
5. Furnace according to claim 1 in which the said conduit has a constant cross-section, the said walls (32) having openings (320) with approximately the said cross-section S in the Y-Z plane, in order to form conduits (5) with an substantially constant cross-section S by a series of hollow walls (3) simultaneously active in the said fire, in which the said degree of homogeneity is achieved by a removable distribution means inserted upstream of the said revolving fire at the upstream end of the said conduit (5) in order to inject the said gas flow with the said degree of homogeneity into each conduit (5).
6. Furnace according to claim 5, in which the said degree of homogeneity is further achieved using the said removable distribution means inserted downstream of the said revolving fire, at the downstream end of the said conduit (5) formed by the series of hollow walls (3) active for the said fire, in order to suck up the said gas flow without disturbing the said degree of homogeneity of the said gas flow on the upstream side.
7. Furnace according to any one of claims 5 and 6, in which the said distribution means is a containment or a parallelepiped shaped distribution panel (232) with a plane horizontal cross-section in the X-Y plane, chosen such that the said containment can be inserted vertically in the said shaft (37) of the said wall (3) or between two sections, and with a plane vertical cross-section in the Y-Z plane slightly smaller than the said cross-section S of the said wall in the Y-Z plane, having a surface parallel to the Y-Z plane provided with openings (2320) with a geometry calculated either to inject the said gas flow with the said degree of homogeneity on the upstream side of the said conduit (5), or to suck up the said gas flow on the downstream side of the said conduit (5).
8. Furnace according to either of claims 1 and 4, in which the said elements or tie beams (33) are profiled so as to reduce the pressure loss in the said gas flow, while providing other required functions in order to maintain a constant separation between the said lateral partitions (38) and to achieve or maintain the said predetermined degree of homogeneity for the gas flow over the said cross-section S.

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