FR3033027A1 - ALAMBIC EQUIPPED WITH A FIRE TOWER WITH REINFORCED INSULATION - Google Patents

Abstract

The object of the invention is a still comprising a boiler (10) adapted to contain a liquid, a closed hearth (14) disposed under the boiler (10) with at least one burner (26) capable of generating hot flue gases as well as a fire tower (16) comprising at least one wall (112) which extends all around the lower part of the peripheral wall of the boiler, characterized in that the wall (112) of the fire tower ( 16) is made of stainless steel and has a heat insulator (114) at its inward facing side and a thermally insulating coating (116) at its outward facing side.

Description

FIELD OF THE INVENTION The present invention relates to a still equipped with a fire tower with reinforced insulation. A still comprises a boiler containing a liquid to be heated, a burner disposed under the boiler. To improve the heat transfer to the boiler, the burner is placed in a chamber called hearth so as to limit thermal losses to the outside. According to a known embodiment, a burner comprises at least one gas supply in the form of at least one ramp at which injectors are provided via which the fuel, especially the gas, leaves. In contact with the oxidant, especially the ambient air, combustion occurs at the outlet of each injector. Vents are provided to penetrate the interior of the fireplace, the air necessary for combustion. The exhaust gases produced during combustion escape via a chimney. To improve efficiency, the very hot exhaust gases are used to heat the boiler before being rejected. For this purpose, an enclosure called a fire tower extends all around the lower part of the peripheral wall of the boiler so that the exhaust gases are in contact with this part of the wall of the boiler before being rejected. . Thus, the boiler and its contents are heated through a first heat transfer type convection at the fireplace and a second heat transfer type conduction at the level of the fire tower. The present invention aims to simplify the design of the fire tower while limiting heat losses so as to increase the thermal efficiency. Thus, the invention relates to a still comprising a boiler capable of containing a liquid, a closed hearth disposed beneath the boiler with at least one burner capable of generating hot flue gas and a fire tower comprising at least one wall which extends all around the lower part of the peripheral wall of the boiler, characterized in that the wall of the fire tower is made of stainless steel and comprises at the level 3033027 2 of its face facing inwards a thermal insulator and at the side facing outwardly a thermally insulating coating. Other features and advantages will emerge from the following description of the invention, a description given by way of example only, with reference to the accompanying drawings in which: FIG. 1 is a cross-section of a still equipped with a burner according to a first variant of the invention, - Figure 2 is a section illustrating in detail the portion of the still of Figure 1 below the boiler, - Figure 3 is a side view of a burner according to FIG. 4 is a top view of the burner of FIG. 3; FIG. 5 is a section of the burner of FIG. 3; FIG. 6 is a cross section of a burner; FIG. According to another variant of the invention, - Figure 7 is a section of a still with a fire tower according to a variant of the invention, - Figure 8A is a top view of a first stage of the tower FIG. 8B is a top view of a second stage of FIG. FIG. 9 is a section of a still with a fire tower according to a variant of the invention. In Figure 1, there is shown a portion of a still comprising a boiler 10 25 supported by a frame 12 and adapted to contain a liquid to be distilled and a closed hearth 14 in the form of a closed chamber, arranged under the boiler 10. The still also comprises a fire tower 16 and a chimney 18 for evacuating the combustion gases generated in the furnace 14. All these elements are known to those skilled in the art and are not further described.

According to one embodiment, the fireplace 14 comprises at least one burner 26 and is delimited by the bottom 20 of the boiler, a peripheral side wall 22 and a substantially horizontal bottom wall 24. Of course, the invention is not limited to this form of focus.

According to one embodiment, the burner 26 comprises at least one porous wall 28, a first face 30 of which is in contact with the hearth and facing the bottom 20 of the boiler and whose opposite face 32 delimits a feed chamber. 34 in a gaseous mixture comprising an oxidizer (air) and a fuel (gas). The fact of using a porous wall 5 makes it possible to improve the heat transfer at the level of the hearth. Indeed, in addition to the flames present at the first face 30 which make it possible to obtain convective heat transfer, the porous wall 28 makes it possible to obtain a heat transfer by radiation. Preferably, the porous wall is a wire mesh.

This lattice is made of knitted metal threads. These metal wires are made of refractory steel and must have good resistance to corrosion at high temperatures. For example, the porous wall is made from a fabric sold under the reference "Bekinit" using metal son of a material marketed under the name "Fecralloy".

Advantageously, this supply chamber 34 is thermally insulated from the furnace so that combustion takes place at the first face 30 of the porous wall and not upstream in the direction of flow of the gas flow referenced 36 (see FIG. 5). For this purpose, thermal insulation means 38 are interposed between the furnace 14 and the supply of a gaseous mixture. This arrangement makes it possible to prevent the self-ignition point of the gaseous mixture from being reached upstream of the porous wall while the burner is placed in the hearth or in contact with the hearth and the temperature in the hearth is much higher than the point of self-ignition. The supply chamber 34 is connected to a supply system 40 of oxidising gas mixture (air) and fuel (gas) via a supply duct 42.

This supply system 40 comprises means for injecting gas and means for injecting air into the supply duct 42. It comprises means for adjusting the ratio between the volume of gas injected and the volume of the gas. injected air, by acting for example on the means for injecting the gas and / or the means for injecting air. Preferably, the ratio between the volume of gas and the volume of air injected is adjusted so as to obtain an excess of air of between 15% and 30% relative to the stoichiometric dosage. Advantageously, the supply system 40 comprises means for blowing the oxidizer, namely air and thus mixing towards the porous wall 28.

This arrangement makes it possible to impose a combustion regime which makes it possible to limit the influence of the draft of the chimney on the combustion, or even to make the latter independent of the draft. This gas flow can vary depending on the desired heating power.

According to one embodiment, the means for injecting the air and the means for blowing air are in the form of a single turbine which imposes a flow of air. The gas injection means are in the form of an injector and allow to adjust the fuel / oxidant ratio. For example, for a still of 25 hl, the flow rate of the turbine is between 0 and 200 10 m3 / h. According to a first embodiment illustrated in FIGS. 1 to 5, the feed chamber 34 is in the form of a substantially parallelepipedal box delimited by a bottom 44, lateral walls 46 and the porous wall 28 which is disposed in parallel at the bottom 44 and spaced from the latter.

The bottom 44 comprises an orifice 48 connected to a first end of the supply duct 42, the other end of which is connected to the supply system 40. As illustrated in FIG. 5, the box comprises inside at least one deflector 50 which deflects the gas flow leaving the supply duct 42 towards the side walls 46 of the box so that the fresh gas mixture entering the box licks the side walls 46 and cools them which tends to limit the temperature rise inside the box. Preferably, the box comprises means for distributing the mixture over the entire surface of the porous wall. Thus, the box comprises a distribution plate 52 parallel to the porous wall and spaced from the latter. This distribution plate 52 comprises a plurality of openings 54 whose shapes, density and distribution make it possible to adjust the distribution of the flow of the gaseous mixture on the surface of the porous wall. According to one embodiment, the distribution plate is a steel sheet with openings 3 mm in diameter and an opening ratio of 4 to 5% (ratio between the area of the solid parts of the plate and that of the openings ). According to one embodiment, the box is made from an assembly of folded sheets to form the bottom 44 and the side walls 46. The upper end of the side walls 3033027 is folded to form a peripheral rim 56 providing a bearing surface for the porous wall 28. The latter is held in place by plates 58 which are attached to the side walls 46, the porous wall 28 being clamped between the peripheral flange 56 and the plates 58.

Advantageously, the plates 58 are not continuous. Thus, the same side of the box may comprise several plates 58. According to one embodiment, the plates 58 are in the form of angles sectioned and spaced apart. This arrangement makes it possible to manage the differences in expansion between the different connected parts. In order to initiate combustion, ignition means 60 are integrated in the porous wall 28 or placed just above the first face 30 of the porous wall 28. According to one embodiment, the ignition means are the shape of an electrode capable of generating a spark between it and the wire mesh. When the gas burner is in the form of a box, the bottom wall 24 of the hearth comprises an opening 62 for at least partially clearing the porous wall. The opening 62 has shapes and dimensions that are substantially identical to the inner periphery 64 of the plates 58 of the box which corresponds to the outer periphery of the active surface of the porous wall. Preferably, the bottom wall 24 comprises a recess for housing the box and bringing the porous wall 28 of the bottom of the boiler.

The opening 62 is delimited by a substantially plane peripheral edge 66. The thermal insulation means 38 in the form of a seal 68 are interposed between the peripheral edge 66 of the opening 62 and the periphery of the box (more precisely the plates 58 of the box), the latter being held pressed towards the edge device 66 by connecting means 70.

According to one embodiment, the seal 68 is composed of glass threads interwoven around a core made of a high-temperature carded glass ribbon. For example, a seal sold under the name "Ferlajoint VHTC" can be used. The connecting means 70 can be made in different ways, such as for example in the form of four grasshoppers.

According to a second embodiment illustrated in FIG. 6, the supply chamber 34 is tubular.

Thus, the supply chamber 34 is delimited by a first tube 72 comprising at least one opening 74 closed by a porous wall 28 likely to be of the same nature as that of the embodiment of FIGS. 1 to 5. The wall Porous 28 is secured to the tube 72 by any suitable means such as welding, riveting or otherwise. Advantageously, the opening or openings are arranged along the upper generatrix of the tube 72 so as to be oriented towards the bottom of the boiler. A second tube 78 is disposed inside the first tube 72, the two tubes 78 and 72 having axes substantially parallel and preferably coincident.

This second tube 78 is connected to the supply duct 42 or corresponds to a portion of this supply duct. It comprises at least one opening 80 allowing the gaseous mixture to pass from the inside of the second tube 78 to the zone situated between the two tubes 72 and 78. According to one embodiment, the opening or openings 80 are arranged along the upper generatrix of the tube 78 so as to be oriented towards the opening or openings 74 of the first tube 72. The shape, the dimensions, the arrangement of the openings 80 are determined according to the distribution of the desired gas flow at the level of the surface of the porous wall (s) 28. Two partitions 82 are interposed between the two tubes 72 and 78 so as to split this zone between the two tubes 72 and 78 into two sectors isolated from one another in a sealed manner. The first sector 84 makes it possible to communicate the openings 74 and 80 and corresponds to a supply chamber. The first sector extends over an angular sector adjusted to the surface of the first tube 72 covered by the porous wall (s) 28.

The other sector 86 comprises the thermal insulation means 38. Thus, this sector 86 is filled with a thermally insulating material in the form of powder or granules such as chamotte and allows the chamber to be isolated. supply and the tube 78 conveying the gas mixture. According to this embodiment, the peripheral lateral wall 22 delimiting the hearth comprises an opening allowing the passage of the tube 72. In FIGS. 7, 8A and 8B, a fire tower is shown enabling the thermal exchanges between the burnt gases from furnace 14 and boiler 10.

The fire tower 16 is delimited by at least one wall spaced from the wall of the boiler, a bottom 88 and an upper wall 90 and communicates in the lower part with the hearth 14 via at least one inlet 92 and in the upper part with a chimney duct 18 via at least one outlet 94.

According to one embodiment, the upper wall 90 is disposed in a horizontal plane disposed below the filling level of the boiler 10. Advantageously, the fire tower 16 comprises at least one partition 96 for channeling the flue gases into the boiler. turn the fire so that they perform at least twice the turn of the boiler between the entrance 92 and exit 94 of the fire. This configuration 10 makes it possible to lengthen the path length of the flue gases in contact with the boiler and to improve the efficiency of the exchange between the flue gases and the boiler. Preferably, the partition is substantially horizontal and divides the fire tower into two compartments (or stages) superimposed on one another, a first lower compartment 98B and a second upper compartment 98H, the lower compartment 98B communicating with the input 92 and the high compartment 98H with the output 94. According to one embodiment, the two compartments 98B and 98H are annular and extend over the entire periphery of the boiler 10. To ensure the passage of flue gases from the bottom compartment 98B to the upper compartment 98H, the partition 96 includes an opening 99 visible in Figure 8A. The inlet 92 and the opening 99 are brought together and separated by a first transverse partition 100 which closes the entire section of the lower compartment 98B so that the flue gases run the longest path in the lower compartment, as shown in FIG. 8A. . The opening 99 and the outlet 94 are brought together and separated by a second transverse partition 102 which closes the entire section of the top compartment 98H so that the flue gases run the longest path in the top compartment, as shown in FIG. 8B. According to another characteristic, the section of the fire tower 16 is reduced from the inlet 92 to the outlet 94 to take into account the cooling of the flue gases and maintain a substantially constant speed of the flue gases in the fire tower 16. Advantageously, the upper compartment 98H has a lower section than the lower compartment 98B as illustrated in FIG. 7.

As an indication, the temperature of the flue gases is of the order of 500 to 650 ° C at the inlet 92 of the lower compartment 98B whereas the temperature at the outlet 94 of the high compartment 98H is In order to take account of this temperature variation, the section of the lower compartment 98B is 1.3 to 1.8 times higher than that of the upper compartment 98H. The invention also proposes a solution illustrated in FIGS. 9 and 10, making it possible to reduce the costs of manufacturing and installing a fire tower and limiting heat losses. In this sense, the fire tower is made from stainless steel walls which are shaped. The bottom 88 of the fire tower is remote from the bottom 20 of the boiler so as to cover the inner face of the bottom 88 with a first thermal insulator 104. For the remainder of the description, the term thermal insulator means a thermal insulator or several thermal insulators for example several layers of thermal insulation contiguous to each other. Carrier structures 106 pass through the first heat insulator 104 and are interposed between the frame 12 and the boiler 10 so as to ensure the recovery of forces, including the weight of the boiler. These bearing structures 106 may be made of a refractory material. According to one embodiment, the first thermal insulator 104 comprises a central cutout whose edge 108 delimits the focus 14. Advantageously, the first thermal insulator 104 comprises at its upper face, a cutout 110 which embodies the inlet 92 of the fire tower and which allows to communicate the fireplace 14 with the fire tower. The thickness of the first thermal insulator 104 is of the order of 150 mm. Advantageously, the first thermal insulator 104 has a thermal resistance of between 1.5 and 2.5 K / W. Despite the high temperature in the firebox and the firebox inlet (greater than 500 ° C), it is possible to use a stainless steel wall to form the bottom 88 and not a refractory material because the insulation 104 makes it possible to reduce the temperature at the wall forming the bottom 88. Advantageously, the first thermal insulator 104 comprises several layers, namely from the inside towards the outside at least one layer of alkaline earth silicate wool 104.1 , a vapor barrier 104.2 and at least one silica airgel mattress 104.3.

According to one embodiment, the first insulator 104 comprises two layers of alkaline earth silicate wool 104.1, a vapor barrier 10.2 in the form of a thin metal sheet, at least one layer of rock wool 104.4 and at least one silica airgel mattress 104.3. The two layers of alkaline earth silicate wool 104.1 have an overall thickness of about 60 to 70 mm. The layer or layers of rockwool 104.4 have an overall thickness of about 80 mm. The silica airgel or mattress 104.3 have an overall thickness of the order of 10 mm. In addition to the bottom 88, the fire tower 16 comprises at least a first cylindrical wall 112 spaced from the boiler.

This cylindrical wall 112 is coated at its inner face (facing the boiler) with a second thermal insulator 114. This insulator 114 makes it possible to reduce the temperature at the inner face of the cylindrical wall 112. Preferably, the second heat insulator 114 has a thickness of the order of 10 to 15 mm. According to one embodiment, the second heat insulator 114 corresponds to one of the layers of alkaline earth silicate wool 104.1 which rises at the level of the cylindrical wall 112. According to another characteristic, the cylindrical wall 112 comprises at the level of its outer face a thermally insulating coating 116. Advantageously, the thermally insulating coating 116 has a thermal resistance of between 2 and 3 K / W. This coating 116 makes it possible to limit the occurrence of a phenomenon of condensation at the inner face of the cylindrical wall 112 in contact with the hot burnt gases. Advantageously, the thermally insulating coating 116 comprises a plurality of layers, i.e. from the inside out at least one rockwool layer 116.1 and at least one silica airgel batt 116.2. The rock wool layer or layers 116.1 have an overall thickness of the order of 120 mm. The airgel or silica air mattress 116.2 have an overall thickness of the order of 20 mm. Preferably, the fire tower comprises several compartments 98H and 98B. In this case, the fire tower comprises a plurality of cylindrical walls 112 and 112 ', the first delimiting the lower compartment 98B and the second the upper compartment 98H, the cylindrical wall 112' having a diameter greater than that of the cylindrical wall 112.

In this case, the second heat insulator 114 covers only the inner face of the cylindrical wall 112. The presence of the second thermal insulator 114 at the cylindrical wall 112 'is not necessary because the temperature of the gases burned in the high compartment 98H is lower than that of the flue gases at the bottom compartment 98B.

In contrast, the thermally insulating coating 116 extends at the outer faces of the two cylindrical walls 112 and 112 '. However, the thickness of the coating 116 is significantly smaller at the cylindrical wall 112 'than the cylindrical wall 112, the thermal resistance at the wall 112' to be between 1 and 2 K / W.

At the cylindrical wall 112 ', the rock wool layer or layers 116.1 have an overall thickness of the order of 40 mm. In addition to the cylindrical walls 112, 112 'and bottom 88, the fire tower comprises a partition 96 which separates the two compartments 98B and 98H and an upper wall 90, both of stainless steel. The partition 96 also provides the junction between the two cylindrical walls 112 and 112 '.

Claims (8)

REVENDICATIONS1. Alembic comprising a boiler (10) adapted to contain a liquid, a closed hearth (14) disposed under the boiler (10) with at least one burner (26) capable of generating hot flue gas and a fire tower (16). ) comprising at least one cylindrical wall (112) which extends all around the lower part of the peripheral wall of the boiler, characterized in that the cylindrical wall (112) of the fire tower (16) is made of stainless steel and comprises at its inward facing face a heat insulator (114) and at its outward facing side a thermally insulating coating (116). 2. Alembic according to claim 1, characterized in that the thermally insulating coating (116) has a thermal resistance of between 1 and 3 K / W. 3. Alembic according to claim 1 or 2, characterized in that the fire tower comprises a bottom (88) remote from the bottom (20) of the boiler and comprises at its inner wall a thermal insulator (104). 4. Alembic according to claim 3, characterized in that the thermal insulation (104) provided at the bottom (88) of the fire tower comprises from the inside to the outside at least one layer of alkaline silicate wool earth (104.1), a vapor barrier (104.2) and at least one silica airgel mattress (104.3). 5. Alembic according to claim 4, characterized in that the thermal insulation (104) provided at the bottom (88) of the fire tower comprises two layers of alkaline earth silicate wool (104.1), a rising to the level of the cylindrical wall (112). 6. Still according to claim 4, characterized in that the thermal insulation (104) provided at the bottom (88) of the fire tower comprises at least one layer of rockwool (104.4) interposed between the firewall (104.2). ) and a silica airgel mattress (104.3). 7. Alembic according to one of the preceding claims, characterized in that the thermally insulating coating (116) comprises at least one layer of rockwool (116.1) and at least one airgel silica mattress (116.2). 8. Still according to one of the preceding claims, characterized in that the fire tower comprises a plurality of compartments delimited by cylindrical walls (112, 112 '), a first cylindrical wall (112) delimiting a bottom compartment (98B) having at least at its outer surface a thermally insulating coating (116) with a thermal resistance of between 2 and 3 K / W and a second cylindrical wall (112 ') delimiting a top compartment (98H) having at its outer surface a thermally insulating coating (116) with a thermal resistance of between 1 and 2 K / W.