ITMI20112364A1 - APPARATUS FOR CLINKER PRODUCTION STARTING FROM A RAW MIXTURE INCLUDING A PREHEAT HEATER WITH CONTENT HEIGHT - Google Patents

Description

APPARATUS FOR THE PRODUCTION OF CLINKER STARTING FROM A RAW MIXTURE INCLUDING A PREHEATER AT LOW HEIGHT

FIELD OF INVENTION

The present invention falls within the scope of the construction of plants for the production of hydraulic binders. More precisely, the present invention relates to an apparatus for the production of clinker starting from raw flour comprising a suspension preheater having a limited vertical height or a reduced environmental impact.

STATE OF THE TECHNIQUE

As is known, cement is a hydraulic binder used to bond inert solid materials, such as sand and gravel, to form concrete and mortars, or the basic components for the construction of buildings.

On an industrial scale, cement is made by mixing and grinding clinker and gypsum with possibly corrective agents such as limestone, slag and pozzolan. The â € œclinkerâ € is nowadays normally obtained through a technology called â € œvia dryâ €, that is it represents the product of a high temperature cooking of a mixture of raw materials consisting mainly of limestone (calcium carbonate) and clay (silica, alumina , iron oxides, as well as water of crystallization). The raw materials are mixed in the solid state in the desired proportions and then finely ground until obtaining a homogeneous powder called â € œcrude flourâ € (or raw mixture). For the purposes of the present invention, the expression â € œcrude flourâ € or â € œcrude mixtureâ € is therefore intended as the homogeneous powder used as starting material for the production of clinker.

The raw flour, once pulverized and dried in a special mill, is dosed in a preheater / calcinator and subsequently transformed into clinker by cooking at a temperature of about 1450 ° C in a rotary kiln essentially consisting of an inclined rotating cylinder. During the heat treatment in the rotary kiln, the raw flour reacts forming the calcium silicates and aluminates (clinkerization reaction) which are the main constituents of the clinker. In clinker production plants known from the state of the art, the raw flour, before being fed to the rotary kiln, is subjected to a preheating and, possibly, pre-calcination treatment. One of the currently most used preheating techniques is based on the use of the so-called `` suspension preheater '' or `` multistage cyclone preheater '' (hereinafter simply `` preheater '') consisting of a tower of cyclones in which each pre-heating stage takes place in one or more cyclone separators. At each pre-heating stage, the flour is first dispersed in a vertical duct in the gaseous stream and is then separated by centrifugal effect in a large diameter cyclone separator (8-9 meters). This vertical duct essentially constitutes a heating stage of the preheater.

Figure 1 is a schematic view of a multi-stage pre-heater known from the state of the art. This pre-heater is in fact comparable to a counter-current heat exchanger in which the flour to be heated descends by gravity from the top to the bottom, while the hot fumes produced in the rotating oven rise up to the top of the pre-heater. The preheater shown schematically in Figure 1 comprises four heating stages. However, the number of such stages may vary according to the applications.

The preheater illustrated in Figure 1, for example, comprises a first heating stage usually defined by a pair of first cyclone separators 301 fed at the inlet by a first supply duct (indicated with reference 401). The latter is crossed by the fumes coming out of a second cyclone separator 302 of a second preheating stage. The flour is introduced into the first duct 401 so that it mixes precisely with the fumes coming from the second separator 302. This first duct 401 usually divides into two branches each directed to the inlet of one of the first cyclones of the first preheating stage. These first separators 301 then perform a first separation between the pre-heated flour and the fumes. In particular, each of the first separators 301 comprises a flour outlet section and a fumes outlet section. In particular, the fumes leaving the first separators 301 are then used in the raw flour grinding / drying plant before being emitted into the atmosphere after dust removal.

The flour leaving the first separators 301 is introduced into a second duct 402 which connects the outlet of a third separator 303 to the feed of the second separator 302 located at a higher height. The flour exiting the latter is subsequently introduced by gravity into a third duct 403 which connects a fourth separator 304 to the third separator 303 which is located at an intermediate height between the second separator 302 and the fourth separator 303. The flour exiting the third separator 303 is inserted in a fourth duct 404 which connects the fourth separator 304 to the outlet of the rotary kiln 500 to be subsequently returned to the fourth separator 304. Inside the latter, the flour is definitively separated from the fumes and carried inside the rotary kiln 500 to undergo transformation into clinker.

The number of pre-heating stages is determined by the humidity of the raw materials to be dried in the grinding / drying plant that uses these gases, and therefore by the amount of thermal energy associated with them, after they have left the preheater itself. In particular, in the presence of a high humidity of the raw materials, a greater quantity of heat is required for drying and therefore preheaters with only four stages will be obtained. In the presence of medium humidity, on the other hand, five-stage preheaters are provided, while in the presence of raw materials with low humidity, six-stage preheaters.

The choice of raw materials with a low degree of humidity as well as the careful design of the vertical ducts and cyclones that form the different heating stages mean that today it is now customary to create five and even six-stage preheaters, with ducts connection verticals long enough to increase the contact times and therefore the heat exchange between gas and matter and ultimately the overall thermal efficiency of the process.

Furthermore, the nominal production capacity of cement kilns has increased significantly in recent years, going from 1000-2000 tpd (tons per day) of clinker, typical of the 70s, up to 5000-7000 tpd, typical of more recent projects. This trend has resulted in an increase in the physical dimensions of the preheaters with proportionately enlarged duct sections and cyclone heights. It follows from all that the suspended preheaters, having in the past heights of 60-80 m, normally exceed 120 m in height and reach 140-150m.

The considerable height of the preheaters determines an important problem of visual environmental impact, previously unheard of as the heights of the preheaters, much lower, did not differ much from the higher storage silos (40-60m). Currently, however, the preheater tower stands out on the profile of the cement factory, becoming a characterizing element of the landscape, visible from great distances. In this sense, the growing sensitivity to environmental problems therefore makes it increasingly difficult for local administrations to obtain the necessary building permits.

As indicated above, the height of a preheater is therefore determined primarily by the number of stages of the preheater itself, which in turn depends in the opposite direction on the humidity of the raw materials. The height of the pre-heater is also linked to the length of the connection ducts, which increases the thermal efficiency of the pre-heater. Finally, as the nominal production capacity increases (ie the daily tons of clinker produced) the size of the preheater and in particular its height increases. In this sense, it should be added that a high daily production of clinker can no longer be separated from the presence of a precalcinator placed between the rotating kiln and the preheater. In traditional solutions, the precalcinator is configured as a central tower next to which the various cyclones that make up the preheater are arranged. The precalcinator reaches considerable heights, in the order of 60-70 meters, thus constituting a drawback in terms of height, but at the same time also a necessary design constraint.

Faced with these evidences, up to now interventions have been adopted in order to contain the overall height of the preheaters intended on the one hand to reduce the height referred to the ground and on the other to reduce their vertical dimensions. In particular, the first type of intervention includes all the plant engineering solutions that envisage reducing the height from the ground of the structures downstream of the preheater itself and therefore of the rotary kiln and cooler. In particular, these structures are placed in the sub-soil in order to reduce the emersion with respect to the soil itself. However, this solution has various drawbacks. First of all, to allow easy maintenance and increase safety levels, it is preferable to have production plants above ground. In this sense, therefore, the solution of placing the structures downstream of the preheater below ground level is obviously not appropriate. Furthermore, the construction of structures below the ground level requires large additional excavations and, where it is desired to reduce the height above the ground of the plants downstream of the cooler beyond a certain limit, there is a limit in the need to be able to pass between the bases. of the rotary kiln to allow acceptable traffic inside the factory.

An alternative solution is that which involves an intervention on the geometry of the preheater tower in order to contain its own height. In particular, the most common intervention is to split the "cluster" of cyclones by actually creating two towers operating in parallel, or as they say in jargon, creating a "two-string" tower. In this case, having each â € œstringâ € a potential equal to half of the total, the dimensions of the cyclones and of the relative ducts decrease and therefore also the overall height becomes more contained. However, this solution has the disadvantage of having construction and maintenance costs that are almost double that of the simple string solution (Figure 1), as well as some difficulties of a management nature. More precisely, it is not easy to maintain the balance between the two strings in terms of gas flow and materials. An alternative solution to the `` two-string '' configuration could be to design a shorter `` square '' tower with cyclones and shorter connection ducts, with obvious sacrifices in terms of thermal efficiency, given that the reduced development of the connection ducts penalizes the gas-material contact times and therefore the heat exchange.

A partial solution to the problem linked to the height of the preheaters is contained in the patent application PCT / IB2009 / 00782. This question shows the technical solution schematized in Figure 2 in which the preheater comprises an electrofilter 450 substantially located â € œon the groundâ € that is substantially at the base of the preheater. The 450 electrofilter is connected to a first cyclone separator 460 through a mainly vertical pipe which defines a loading section for the flour. The fumes coming out of the first separator 460 mix with the flour introduced into the vertical pipe which reaches the inlet 453 of the electrofilter 450. The separation by electrostatic precipitation takes place inside the latter. The fumes coming out of the electrophore 450 are treated by a catalytic system 500 of fumes treatment for the reduction of NOx, while the flour is brought back upwards to be introduced into a 470 pipe which connects the a second cyclone separator 465 with the inlet of the first separator 460.

Compared to the solution in Figure 1, the use of an electrofilter 450 at the base of the preheater leads to a reduction in the height of the preheater since, for the same number of heating stages, the difference in level is effectively eliminated (indicated by 501 in Figure 1) required for positioning the first separators (indicated with the reference 301 in Figure 1). It has been seen, however, that this solution is not sufficient in itself to satisfactorily solve the problem of height as the reduction in height allowed (in the order of about ten meters) is not sufficient to reduce the environmental impact significantly.

On the contrary, it has been seen that the solution shown in Figure 2 actually introduces a further problem linked to the movement of the flour out of the Itro 450 electrophile. œtraditionalâ € of the preheater determine a considerable difference in height (indicated with 502) between the flour outlet 451 from the electrofilter 450 and the loading section of the second pipe 470 between the first separator 460 and the second separator 465. To allow the flour to overcome this difference in height 502, it is necessary to provide suitable operational means for feeding the flour. The power required by these means of supply depends on the one hand on the extent of this difference in height 502 and on the other on the length of the pipes used for transporting flour. In fact, as their length increases, the required power increases.

It is therefore evident that with a traditional preheater scheme, as the heating stages increase (i.e. the number of cyclone separators), the difference in level 502 to be overcome increases directly as does the power required by the operating means of supply. of the flour. It is therefore evident that the use of the 450 electrofilter, while advantageous in terms of height reduction, does not combine well with the â € œ clusterâ € structure of the traditional preheaters shown in figures 1 and 2.

Therefore, on the basis of the above considerations, the need clearly emerges to have alternative technical solutions to those indicated above and so far developed to contain the height dimension of the preheaters without limiting, at the same time, their efficiency and production capacity. Therefore, the main task of what forms the subject of the present invention is to provide an apparatus for the production of clinker starting from raw flour which allows the above mentioned drawbacks to be overcome. In the context of this task, a first aim is to provide an apparatus for the production of clinker which, with the same productivity, has a lower height from the ground than that of traditional solutions. Another object of the present invention is to provide an apparatus for the production of clinker in which the structure of the preheater is optimally combined with the presence of an electrofilter. Not least object is to provide an apparatus which is easy to reliable and easy to manufacture at competitive costs.

SUMMARY

The present invention therefore relates to an apparatus for the production of clinker starting from raw flour. The apparatus includes a rotating kiln and a precalcinator communicating with the rotating kiln so as to be crossed by the combustion fumes generated in the kiln itself. The precalcinator comprises a fume inlet section which defines a substantially horizontal reference base plane. The apparatus according to the invention comprises a suspension preheater which develops above this reference base plane to heat the flour through a heat exchange with the combustion fumes leaving the precalcinator. In particular, this preheater includes:

- a first cyclone separator comprising a feed section for the flour mixed with the fumes, a fume outlet section and a flour outlet section;

- at least one separation electrofilter located in a position below the first separator; this electrofilter comprises a feed section for the flour mixed with the fumes, a fumes outlet section and at least one flour outlet section;

- a first feeding and heating pipe which connects the feeding section of the electrofilter with the fume outlet section of the first separator, said first pipe comprises a first flour discharge section;

- at least a second cyclone separator comprising a feed section for the flour mixed with the fumes, a smoke outlet section and a flour outlet section;

- a second feeding and heating pipe which connects the flue outlet section of the second separator to the feeding section of the first separator; said second pipe comprising a second loading section of said flour;

- operational means for feeding the flour to move the flour from the outlet section of the electrofilter to the second loading section of the second pipe.

The apparatus according to the invention is characterized by the fact that the first separator and the second separator of the preheater are arranged substantially at the same height with respect to the base reference plane so that the respective smoke outlet sections define a first substantially horizontal reference plane. Furthermore, according to the invention, the second pipe has a first section that develops in a position below the first floor and a second section that develops above the same first floor so as to define respectively a point of maximum height and a point of minimum height of the second pipe. Furthermore, the second loading section of the second pipe is defined by said first section of the second pipe.

The use of two separators placed at the same height reduces the overall height of the preheater compared to traditional solutions in which the separators are cascaded at different heights. It has been seen that the use of a pipeline that extends from opposite sides to the first reference plane allows advantageously to limit the amount of height difference between the flour outlet section of the electrofilter and the loading section defined on the same second pipe. This results in an advantageous reduction of the path necessary for the movement of the flour and therefore of the power required by the means for feeding the flour itself.

LIST OF FIGURES

Further characteristics and advantages will be evident from the following detailed description of preferred embodied forms of the apparatus for the production of clinker according to the present invention illustrated by way of non-limiting example in the accompanying drawings in which:

- Figure 1 is a schematic view relating to a first apparatus for the production of clinker starting from raw flour of a known type;

- Figure 2 is a schematic view relating to a second apparatus for the production of clinker starting from raw flour of a known type;

Figure 3 is a schematic view relating to a possible embodiment of an apparatus according to the present invention;

- Figure 4 is an enlargement of detail IV defined by the dashed line in Figure 3;

- Figure 5 is an enlargement of the detail V defined by the dashed line Figure 3.

The same reference numbers and letters in the figures identify the same elements or components.

DETAILED DESCRIPTION

With reference to the aforementioned figures, the present invention relates to an apparatus 1 for producing clinker starting from raw flour. The apparatus 1 according to the invention comprises a rotating kiln 10 and a precalcinator 12 communicating with the rotating kiln 10 so as to be crossed by the fumes generated in the kiln itself. More precisely, the rotary kiln 10 comprises an outlet section 10â € ™ fumes communicating with an inlet section 12â € ™ of the precalcinator 12. This inlet section 12â € ™ defines a base plane 100 of substantially horizontal reference from which it develops, in vertical direction, the precalcinator 12. The vertical dimensions of the latter can vary according to the productivity required of the apparatus 1 according to per se known criteria.

The apparatus 1 according to the invention comprises a suspension pre-heater (hereinafter referred to simply as "preheater") to heat the raw flour destined for the rotary kiln 10 through a heat exchange with the combustion fumes generated in the rotary kiln 10 and outgoing from the precalcinator 12. In particular, the preheater is of the suspension type with cyclone separators. From the constructive point of view, the preheater develops next to the pre-calcinator, according to an arrangement criterion known per se. in this sense, therefore, the embodiments shown in Figures 3 and 4 are to be considered exclusively schematizations having the sole purpose of showing the reciprocal vertical arrangement of the different separators that make up the preheater.

Figures 3 and 4 relate to an apparatus according to the invention indicated with the reference 1. The preheater of the apparatus 1 comprises a first feeding and heating pipe 32 inside which the raw flour previously treated according to procedures of known per se (for example pulverization and drying in a special mill). In particular, the first pipe 32 comprises a first loading section 32â € ™ through which the flour is inserted. The first pipe 32 is crossed by the combustion fumes generated inside the rotary kiln 10 and inside it a â € œfirst stageâ € of heating the flour mixed with said fumes is created. The preheater of the apparatus 1 comprises at least a first cyclone separator 30 and a second cyclone separator 40 arranged at the same height with respect to the base plane 100 of reference indicated above. Said separators 30, 40 have a known structure. In particular, each of them comprises an upper portion having a substantially cylindrical shape from which a substantially funnel-shaped lower portion develops. For each of the two separators 30,40 the upper portion defines a feed section 3T, 4T of a flour-fumes mixture. This feeding section 3T, 4T is defined in such a way as to allow a tangential entry of this mixture inside the separator.

For each of the separators 30, 40 the upper portion also defines a fume outlet section 31â €, 41â € which allows a substantially vertical exit of the fumes from the separator itself. Finally, for each of the two separators 30, 40, the lower funnel-shaped portion defines, near the more tapered part, an outlet section 31 "', 41â €' of the flour (hereinafter referred to as the flour outlet section 31â € ', 41â € â € ™).

The preheater also comprises an electrofilter 450 for separating the flour from the fumes. This electrofilter 450 is placed in a position at least below the first separator 30. The electrofilter 450 includes a 1 T feeding section of the flour-fumes mixture, a fume outlet section 11â € and a 1 T flour outlet section. . The flue gas outlet section 11â € is connected to a flue gas discharge pipe 28 at the end of which there is an aspirator 29 to generate sufficient suction conditions to ensure a constant flue gas flow through the preheater and precalcifier 12.

The first pipe 32 indicated above connects the supply section 1 T of the electrophore 450 with the fumes outlet section 31â € of the first separator 30. A second supply and heating pipe 42 instead connects the fumes outlet section of the second separator 40 with the feeding section 3T of the first separator 30. This second pipe 42 defines a â € œsecond stageâ € of heating for the flour and includes a second loading section 42â € ™ through which the flour coming out of the electrofilter 450 is inserted in the same second pipe 42. In this regard, the preheater is equipped with operational means for feeding the flour (described later) to move the flour from the outlet section 11â € â € ™ of the electrophore 450 up to the second outlet section 42â € ™ of the second pipe.

According to the present invention, the first separator 30 and the second separator 40 are arranged at the same height with respect to the base plane 100 of reference indicated above. With this we want to indicate a condition such that the fumes outlet section 31â € of the first separator 30 and the fumes outlet section 41â € of the second separator 40 are located substantially at the same height H with respect to the base plane 100, defining themselves a first substantially horizontal reference plane 101. According to the present invention, the second pipe 42 has a first section 33â € ™ which extends below the first floor 101 and a second section 33â € which extends over the same first floor 101. The first section 33â € ™ e the second section 33â € essentially defines a point of minimum height 72 and a point of maximum height 71 of the second pipe 42 with respect to the reference base plane 100. Furthermore, according to the present invention, the first section 33â € ™ of the second pipe 42 defines the second loading section 42â € ™ indicated above intended to be fed by the flour coming out of the electrofilter 450.

The arrangement of the two separators 30, 40 and the conformation of the second pipe 42 allow a considerable reduction in the overall height of the preheater compared to known solutions in which the cyclone separators are arranged at different heights as shown in Figures 1 and 2. In in particular, it has been seen that these solutions have a synergistic effect in terms of limiting the overall height of the preheater. In fact, not only is the typical difference in height typically existing between two contiguous separators (see Figure 1) reduced, but the space between the same separators is advantageously exploited to define a flour heating stage. In substance, through this solution the preheater is advantageously compacted downwards, that is towards the base plane 100. Furthermore, through the particular shape of the second pipe 42 the height of the second loading section is also advantageously reduced and consequently the work is reduced. required to the means of supply for the lifting of such flour.

From the structural point of view, the first separator 30 and the second separator 40 as well as a similar conformation preferably also have the same vertical extension, measured starting from the respective smoke outlet section 31â €, 41â € up to the respective flour outlet section 31â € â € ™, 41â € â € ™. In particular, the two separators 30, 40 have a height such that the flour outlet section 31â € ™ â € of the first separator 30 and the flour outlet section 41â € â € ™ of the second separator 40 are substantially arranged on a second plane 102 of substantially horizontal reference and underlying said first floor 101. In this regard, according to a preferred embodiment, the first section 33â € ™ of the second pipe 42 develops in such a way that the point of minimum height 72 is in a position below said second level 102. Also the second loading section 42â € ™ is preferably defined in the position below this second floor 102. This solution allows a further reduction of the difference in height between the flour outlet section 11â € ™ â € electrofilter 450 and the second section of 42â € ™ load which translates into a further reduction of the work required to move the flour and therefore in a further containment in terms of encumbrance ro and power of the operating means for feeding the flour.

With reference in particular to Figure 4, the first section 33â € ™ of the second pipe 42 communicates with the supply section 31â € ™ of the first separator 30 and has a substantially U-shaped conformation developing completely below the first floor 101 and precisely defining the point of minimum height 72 of the second pipe 42. The second section 33â € of the second pipe 42 is instead conformed to an inverted U, meaning with this expression a section folded in order to define a curve of 180 that extends towards the first floor 101 precisely defining a point of maximum height 71 for the pipe itself.

As shown in Figure 4, the second pipe 42 also includes a connecting section 34, at least partially curved, which is connected to a first branch of the first section 33â € ™ U-shaped, also developing below the first floor 101. The connecting portion 34 essentially defines the end part of the second pipe 42 connected to the first separator 30. The second pipe 42 finally comprises a central straight portion 35 which connects a second branch of the first U-shaped portion 33 with a first branch of the second section 33â € in an inverted U shape. A second branch of the second section 33â € is instead connected to the smoke outlet section 41 "of the second separator 40.

In the solution illustrated in Figures 3 to 5, a first vertical portion (indicated by the reference 37 in Figure 3) of the first section 33â € ™ of the second pipe 42 defines the second section 42 'of the flour. This solution makes it possible to avoid, or in any case reduce, the possible deposits of flour in the point of minimum height 72 defined by the U-shaped conformation of the first section 33â € ™. In this regard, according to a preferred embodiment of the invention, not illustrated, the second pipe 42 comprises means for evacuating the flour located near this point of minimum height 72 to remove any flour residues that may accumulate in correspondence with this point.

In the form illustrated in Figures 3 to 5, the preheater of the apparatus 1 comprises a third cyclone separator 50 having a structure substantially equivalent to that of the first separator 30 and the second separator 40. More precisely, the third separator 50 comprises a section of supply 51 a smoke outlet section 51â € and a flour outlet section 51â € ™ (shown in Figure 4). The third separator 50 is arranged in a position below the first reference floor 101 and such that the fumes outlet section 51â € is located on a third reference floor 103 below the first floor 101 and the second reference floor 102.

The fumes outlet section 51â € of the third separator 50 is connected to the supply section 41 â € ™ of the second separator 40 by means of a third pipe 52 which has a per se known conformation that is comprising a substantially vertical straight section, outgoing from the flue outlet section 51â € of the third separator 50, and a bend that connects the straight section to the supply section 41â € ™ of the second separator 40. This third pipe 52 essentially defines a â € œthird stageâ € â € Heating of the flour which is introduced through a third loading section 52â € ™. This latter is connected to the flour outlet section 3Tâ € of the first separator 30 through a first flour adduction duct 39â € ™ configured in such a way that said flour reaches this third loading section 52â € ™ by gravity.

The preheater according to the invention also comprises a fourth cyclone separator 60 with a shape substantially corresponding to that of the third separator 50. With reference again to Figures 3 and 4, the fourth separator 60 comprises a supply section 6T connected to the outlet of the pre-calcinator 12 and a fume outlet section 61â € connected to the supply section 5T of the fourth separator 50 through a fourth feeding and heating pipe 62 which essentially defines a "fourth stageâ € of flour heating. sense, it is observed that the fourth pipe 62 includes a fourth section 62â € ™ for loading the flour connected to the flour outlet section 4Tâ € of the second separator 40 through a second duct 39â € ™ for feeding the flour. Also this second pipe 39â € ™ It is configured to allow the flour to slide by gravity towards the fourth section 62 '.

As shown in the figures, the fourth separator 60 is located in a lower position than the first reference plane 101. More precisely, the fumes outlet section 61â € of the fourth separator 60 lies on the third floor 103 identified by the fumes outlet section 51â € of the third separator 50. In other words, the third separator 50 and the fourth separator 60 are at the same height H2 with respect to to the reference base plane 100 above which the preheater develops. With reference in particular to Figure 4, the fourth pipe 62 preferably comprises a first section 64â € ™ bent substantially into an inverted U shape and a second connecting section 64 "which connects the first section 64â € ™ to the supply section 51â € ™ of the fourth separator 50. The expression â € œfolded into an inverted Uâ € means a section folded in such a way as to define a curve of about 180 degrees that extends towards the third floor 103 defining a point of maximum height 66 for the same fourth pipe 62.

As indicated above, the feeding section 61â € ™ of the fourth separator 60 is connected to the outlet section 12â € of the precalcinator 12 through a fifth feeding and heating pipe 72 which defines a â € œfifth stageâ € of flour heating. This fifth pipe 72 is crossed by the combustion fumes generated by the rotary kiln 10 into which the flour is introduced through a loading section 12â € ™ of the precalcinator 12 (indicated in Figure 3). The latter is connected to the 5Tâ € flour outlet section of the third separator 50 through a third supply duct 39â € which allows the flour itself to slide by gravity. The fourth separator 60 comprises a flour outlet section 6 Disconnected to the inlet section 10â € ™ of the rotary kiln 10â € ™ through a fourth duct 39â € ™ for feeding the flour.

The fifth pipe 72 develops partially in the upper position and partially in the lower position to a fourth substantially horizontal reference plane 104 defined by the flue outlet section 12â € of the precalcinator 12. In particular, the fifth pipe 72 comprises a first section 82â € ™ of extremity having an inverted U shape. A first portion of this first section 82â € ™ is connected to the outlet section 12â € of the pre-calcinator 12, while a second portion is folded with respect to the first so as to define a curve of about 180 degrees which extends towards the fourth floor 104 thus defining a point of maximum height 82 for the fifth pipe 62.

The latter also includes a second straight section 82â € which extends from the second portion of the first section 82â € ™ up to a height close to the third floor 103. The fifth pipe 72 finally includes a connecting section 82â € ™ â € which connects the second section 82â € straight with the supply section 61 'of the fourth separator 60. The third section of connection 82â €' is substantially curved so as to constitute a â € œtract of minimum extensionâ € or so as to connect the second section 82â € with the feeding section 61â € ™ of the fourth separator 60 with minimum spatial development.

With reference again to Figure 5, the first pipe 32 comprises a first section 23â € ™ having an inverted U-shape such that a first portion is connected to the smoke outlet section 31â € ™ of the first separator 30 and a second portion of the same first section 23â € ™ is folded with respect to the first portion so as to define a curve of about 180 degrees which extends towards the first floor 101 so as to define a point of maximum height 92 of the first pipe 32. This last includes in addition, a second straight section 23â € which extends from the second portion of the first section 23 to a height close to that of the power supply section 11 of the electrofilter 450.

The second straight section 23â € ™ defines the first loading section 32â € ™ through which raw flour is inserted in order to mix it with the fumes coming from the second separator 30. In particular, this first loading section 32â € ™ It is defined at a height close to that of the first floor 101 in order to increase the extension of the path of the smoke-flour mixture inside the first pipe 32 or in order to increase the efficiency of the flour heating to loss of fumes.

With reference to Figures 3 to 5, as indicated above, the preheater of the apparatus 1 according to the invention comprising operating means for feeding the flour to move the flour exiting the electrophore 450 up to the second loading section 42 of the second pipe 42 which connects the supply section 31â € ™ of the first separator 30 with the smoke outlet section 41 "of the second separator 40.

These operating means comprise at least one supply duct 70 which operatively connects the flour outlet sections 11â € â € ™ of the electrofilter 450 with the second loading section 42â € ™ of the second pipe 42. The supply means also comprise a propulsion device 77 designed to give the flour a sufficient thrust to overcome the difference in height the flour outlet sections 21â € ™ â € ™ of the I â € ™ electrophi Itro and the loading section 42â € ™ of the second pipe 42. This propulsion device 77 can be, for example, of the pneumatic type, ie such as to move the flour upwards through the use of air / gas. Alternative but functionally equivalent embodiments of the propulsion device 77 and in general of the operating means for feeding the flour must in any case be considered as falling within the scope of the present invention.

In order to further contain the amount of work required of these operating means, the second flour pipe 42 can be configured in such a way as to further reduce the point of minimum height 72 or in order to consequently lower the position of the second section. loading 42â € ™ of the flour. In this regard, in Figure 5 the dotted line indicates an alternative form for which the point of minimum height 72 of the second pipe 32 is located below the third floor 103 defined by the position of the third separator 50 and the fourth separator 60.

Preferably also the loading section 42 'occupies a position below this third reference plane 103. As evident from figure 5, this solution allows a strong reduction of the height difference H3 between a fifth reference plane 105 and a sixth reference plane 106, respectively characteristic of the position of the flour outlet sections 1Tâ € of the electro-liter 450 and of the position of the second section 42â € ™ of flour loading. As already indicated above, the lowering of the position of the second loading section 42â € ™, due to the particular conformation of the second pipe 42, results in an advantageous decrease in the power required to the propulsion device 77 or a reduction in overall dimensions and the costs of the operating means for feeding the flour.

With reference again to Figure 3, it is observed that the point of maximum height 92 of the first pipe 32, the point of maximum height 72 of the second pipe 42 and the point of maximum height 82 of the fifth pipe 62 are substantially at the same height H1 with respect to to the base plane 100 of reference. In other words, according to this solution, a plane of maximum height 107 is identified for the pre-heater.

For the sake of completeness, the operating principle of the preheater of the apparatus 1 shown in figures 3, 4 and 5 is described below. In particular, in the figures, the solid line indicates the movement of the combustion fumes inside the preheating the movement of the raw flour is indicated with the discontinuous / dashed line. The raw flour is inserted, through the first section 32â € ™, inside the first pipe 32 in the traditional way and mixes with the fumes coming out of the first separator 30. Going through the first pipe 32, the flour undergoes a first heating as a result of a first heat exchange with the fumes. At the end of the first pipe 32 the fume-flour mixture reaches the electrofilter 450 inside which the flour is separated by precipitation from the fumes. The latter are conveyed in the exhaust pipe 28 towards the aspirator 29.

The flour coming out of the electroof liter 450 is moved, through the operating means of adduction 70, 77 to the second loading section 42â € ™ of the second pipe 32. Inside this last, the flour mixes with the fumes coming from the second separator 40 undergoing a second heating as a result of a second heat exchange with the same fumes. Once through the second pipe 42, the flour-fumes mixture reaches the second separator 40 in which the flour is separated from the fumes for the second time. The latter retrace the first pipe 32, while the flour reaches the third section 52â € ™ of the third pipe 52 which connects the smoke outlet section 51â € of the third separator 50 with the supply section 41â € ™ of the second separator 40. Mixing with the fumes leaving the third separator 50, the raw flour undergoes a third heating and is then separated again from the fumes themselves inside the second separator 40.

Through the second supply pipe 39â € ™, the flour reaches the fourth pipe 62 which connects the smoke outlet section 61â € of the fourth separator 60 with the supply section 51 'of the third separator 50. The raw flour is thus mixed again with the fumes in a position close to the fumes outlet section 61â € of the fourth separator 60 to cross the fourth pipe 62 for almost all of its extension, thus undergoing a â € œfourth heatingâ € which substantially ends when the third separator 50 is reached. Inside the latter, the flour separates from the fumes to be subsequently transported, through the third supply duct 39â €, inside the pre-calcinator 12 in order to generate another mixture with the fumes at high temperature coming directly from the rotary kiln 10.

The raw flour mixed with these fumes rises vertically to the pre-calcinator 12 for its entire height and then passes through the fifth pipe 72 up to the fourth separator 60 where it undergoes the last stage of separation. During the passage in the pre-calciner 12 and in the fifth pipe 72, the flour undergoes a sixth heating. The flour coming out of the fifth separator 60 finally reaches the feeding section of the rotary kiln 10 inside which the flour calcination process is completed.

The apparatus for the production of clinker thus conceived is susceptible of numerous modifications and variations, all falling within the scope of the inventive concept; furthermore, all the details may be replaced by other technically equivalent ones. In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

Claims (2)

CLAIMS 1) Apparatus (1) for the production of clinker starting from raw flour, said apparatus (1) comprising a rotating kiln (10) and a precalcinator (12) communicating with said rotating kiln (10) so as to be crossed by the fumes of combustion generated in said rotary kiln (10), said precalcinator (12) comprising a fume inlet section (12 ') which defines a substantially horizontal reference base plane (100), said apparatus (1) comprising a preheater in suspension act to heat said flour through a heat exchange with said combustion fumes leaving said precalcinator (12), said preheater comprising: a first cyclone separator (30) comprising a feeding section (31 '), a fume outlet section (31â €) and a flour outlet section (31â €'); at least one electrofilter (450) for separating said flour from said fumes placed in a position below said first separator (30), said electrofilter (10) comprising a supply section (11â € ™), a smoke outlet section (11â €) and at least one flour outlet section (11â € ™ â €); a first supply and heating pipe (32) which connects said supply section (11â € ™) of said electrofilter (450) with said fume outlet section (31â €) of said first separator (30), said first pipe (32 ) including a first section (32â € ™) for loading flour; at least a second cyclone separator (40) comprising a feeding section (41â € ̃), a fume outlet section (41â €) and a flour outlet section (41â € â € ™); a second feeding and heating pipe (42) which connects said flue outlet section (41â €) of said second separator (40) to said supply section (31â € ™) of said first separator (30) said second pipe (42 ) comprising a second loading section (42â € ™) of said flour; operational means for feeding the flour to move said flour from said at least one outlet section (11â € â € ™) of said electrofilter (450) to said second loading section (42â € ™) of said second pipe (42), characterized in that said first separator (30) and said second separator (40) are arranged substantially at the same height with respect to said reference base plane (100) in such a way that the respective smoke outlet sections (31 -, 41 â €) define a first plane (101) of reference (101) which is substantially horizontal and by the fact that said second pipe (42) has a first section (33â € ™) which develops in a position below said first floor (101 ) and a second section (33â €) which extends above said first floor (101) so as to define respectively a point of maximum height (71) and a point of minimum height (72) of said second pipe (42) , said first section (33â € ™) of said second pipe (42) defining said second loading section (42â € ™). 2) Apparatus (1) according to claim 1, wherein said first separator (30) has a height substantially equivalent to that of said second separator (40) such that the flour outlet section (31 ...) of said first separator (30) and the flour outlet section (41â € â € ™) of said second separator (40) are substantially arranged on a second reference plane (102) substantially horizontal and below said first plane (101) , said first section (33â € ™) of said second pipe (42) developing in such a way that said point of minimum height (72) is in a position below said second floor (102), 3) Apparatus (1) according to claim 2, wherein said first section. (33â € ™) of said second pipe (42) defines said second loading section (42â € ™) in a position below said second floor (102). 4) Apparatus (1) according to any one of claims 1 to 3, in which said first section (33â € ™) is substantially U-shaped and communicates with said supply section (31â € ™) of said first separator (30) and in which said second section (33â €) is substantially shaped like an inverted U and is communicating on a first side with said first section (33 ') and on a second side with said smoke outlet section (41â €) of said second separator (40). 5) Apparatus (1) according to claim 4, wherein said second pipe (42) comprises a connecting portion (34), at least partially curved, connected on one side to said supply section (31â € ™) of said first separator (30) and from the other to said first section (33â € ™) substantially U-shaped, said second pipe (42) comprising a central straight section (35) that connects said first section (33â € ™) to said second stretch (33â €). 6) Apparatus (1) according to any one of claims 1 to 5, wherein said preheater comprises: a third cyclone separator (50) comprising a feeding section (51â € ™), a fume outlet section (51â €) and a flour outlet section (51â € â € ™), said third separator (50) being arranged in a position such that said outlet section (51â €) of said third separator (50) defines a third reference plane (103) substantially horizontal and underlying said first reference plane (101), a third feeding and heating pipe (52) which connects said fume outlet section (51â €) of said third separator (50) with said supply section (41â € ™) of said second separator (40), said third pipe ( 52) comprising a third loading section (52â € ™) connected to said flour outlet section (31â € â € ™) of said first separator (30) through a first supply duct (39). 7) Apparatus (1) according to claim 6, wherein said preheater comprises: a fourth cyclone separator (60) comprising a feeding section (61â € ™), a fume outlet section (61â €) and a flour outlet section (61â € â € ™), said fourth separator (60) being arranged in a position such that said outlet section (61â €) of said fourth separator (60) is located substantially on said third reference plane (103); a fourth feeding and heating pipe (62) which connects said a fume outlet section (61â €) of said fourth separator (60) to said supply section (51â € ™) of said third separator (50), said fourth pipe (62) comprising a fourth loading section (62â € ™) connected to said flour outlet section (41â € â € ™) of said second separator (40) through a second supply duct (39â € ™); a fifth feeding and heating pipe (72) which connects said feeding section (61â € ™) of said fourth separator (60) to said outlet section (12â €) of said precalcinator (12). 8) Apparatus (1) according to claim 6 or 7, wherein said fourth pipe (62) comprises a first section (64â € ™) folded into an inverted U that extends above said third floor (103) and a second connecting section (64â €) that connects said first section (64â € ™) to said supply section (51â € ™) of said third separator (50). 9) Apparatus (1) according to claim 7 or 8, wherein said outlet section (12â €) of said precalcinator (12) identifies a fourth reference plane (104) substantially horizontal and overlying said third plane (103), said fifth pipe (72) comprising: a first end section (82â € ™) connected to said outlet section (12â €) of said precalcinator (12), said first section (82â € ™) developing above said fourth floor (104) according to a substantially upside down U; a central straight section (82â €) which develops vertically from said first section (62) up to a height close to that of said third floor (103); a second end section (82â € â € ™) which connects said central section (82â €) to said feeding section (61â € ™) of said fourth separator (60). 10) Apparatus (1) according to any one of claims 1 to 9, wherein said supply means comprise: at least one supply duct (70) which operatively connects said flour outlet section (11â €) of said electrofilter (450) to said second loading section (42â € ™) of said second pipe (42), a propulsion device (77) to give said flour a sufficient thrust to overcome the difference in height between said outlet section (11â € â € ™) of said electrofilter (450) and said second loading section (42â € ™) of said second pipe (42). 11) Apparatus (1) according to any one of claims 1 to 10, wherein said first section (33â € ™) of said second pipe (42) extends below said first floor (101) in such a way that said point of minimum height (72) is located in a position below said third reference plane (103). 12) Apparatus (1â € ™) according to any one of claims 10 to 12, wherein said first pipe (32) comprises: a first section (23â € ™) having an inverted U-shape that extends above said first reference floor (101); a second straight section (23â €), connected to said first section (23â € ™), which extends up to a position close to said supply section (11â € ™) of said electrofilter (450); a connecting section (23â € ™ â €) which connects said straight section (23â €) to said supply section (11â € ™) of said electrofilter (450); 13) Apparatus (1 ') according to claim 12, in which said first loading section (32') of said first pipe (32) is defined on said second straight section (23 ') in a position proximal to said first floor (101).