Rotary air lock and installation comprising it

Abstract

Lock 1, comprising a cylindrical body whose inner walls form a stator 2 in which is mounted a honeycomb wheel 3 which can be driven in rotation, said honeycomb wheel 3 comprising a transverse shaft 30 from which rigid blades 4 extend radially and regularly, each having on its free edges 42, 43, on the front face 40, a sealing element 5 between the honeycomb wheel 3 and the stator 2, each of the blades 3 of the rotary air lock 1 comprising on its free edges 42, 43, on the rear face 41, a rear sealing element 6 between the honeycomb wheel 3 and the stator 2, the two front and rear sealing elements 5, 6, the edges 420, 430 of the free edges 42, 43 of each blade 4 delimiting an intermediate chamber 7. Installation implementing a transfer of material, comprising at least one such lock 1. Drawing: Fig 2

Description

Title of the invention: Rotary air lock and installation comprising it

[0001] The technical field concerns that of protection systems commonly called "rotary air lock", "rotary air lock with flexible blades", "honeycomb wheel airlock" or "rotary explosion isolation valve" and installations comprising such protection systems.

[0002] These protection systems are ATEX certified (abbreviation from the terms ATmosphère EXplosive which corresponds to an area in which the explosive risk is present, that is to say where there is a concentration of flammable materials which could ignite or explode) according to the harmonized standard NF EN 15089 within the framework of directive 2014 / 34 / EU.

[0003] A rotary air lock is used in an installation comprising different successive zones for transporting and storing flammable materials, generally dry or granular powdery materials, such as for example cereals, flours, sawdust.

[0004] A rotary air lock can be used in installations linked for example to the food, beverage, bioenergy, wood, chemical, fertilizer, cement, glass or mineral processing, plastics or rubber industries.

[0005] A rotary air lock can be used in industrial dust collection systems and industrial process filtration systems, centralized ventilation and vacuum systems, or pneumatic transfer systems.

[0006] A rotary air lock is interposed between two successive zones and serves as a decoupling unit. It allows the evacuation of material from one zone to a following zone while ensuring a seal between the two zones not allowing a spark or flame to pass from one zone to the other.

[0007] In the case of an explosion, sparks and flames are accompanied by overpressure.

[0008] The air lock is a piece of equipment which has three functions, namely firstly to ensure decoupling between two ATEX zones by ensuring that the barrier to flame, sparks and overpressure is guaranteed, secondly to ensure a seal against pressure or depression between two pieces of equipment subjected to different pressures, and this to guarantee their respective proper functioning, and thirdly to evacuate material without creating a source likely to trigger an explosion caused for example by heating, friction, static electricity.

[0009] The installation may include explosion vents, located for example on silos or filtration systems, which allow unwanted overpressure to be evacuated, in order to avoid the formation of the explosive phenomenon, and in the event of an explosion, allow directed evacuation of heat and flames. The explosion vents are usually calibrated to activate at a pressure difference of 0.1 bar, which corresponds substantially to a relative pressure or depression of 104 Pa.

[0010] A rotary air lock also allows a transfer of material from one zone at a defined atmospheric pressure to another zone at another defined atmospheric pressure, different from the first. This relative pressure difference between the two zones can be between 0 and 0.1 bars, which corresponds substantially to a relative pressure or depression of between 0 and 104 Pa, or even more.

[0011] This pressure barrier function is important so as not to disrupt the operation of the installation.

[0012] The rotary air lock therefore ensures in particular a flame and spark barrier function, and a pressure barrier function while allowing the transfer of material.

[0013] An air lock can be installed for example between two transport systems, pneumatic or mechanical, as well as at the outlet of filters and cyclones, i.e. a separator which uses centrifugal force to purify air loaded with chips or dust.

[0014] A rotary air lock comprises, in a known manner, a transversely extending cylindrical body forming a stator, with two substantially opposite transverse peripheral openings, said body comprising interior walls defining an interior volume traversed transversely by a shaft from which extend blades having a flexible end forming a seal which provides a seal by friction with the stator, the blades cutting the interior volume into cells.

[0015] The shaft and blades form a honeycomb wheel pivoting in the stator.

[0016] In a known manner, the peripheral openings are located respectively at the top and bottom of the stator, to assist the passage of the material through the gravity lock, and are connected to material conveying installations or networks.

[0017] The shaft is driven in rotation by an electric motor, with or without a rotation speed variation system.

[0018] In a known manner, the blades of the honeycomb wheel are in the form of a rigid steel plate, they are made in one piece with the shaft, assembled by welding or by any other means of reversible or non-reversible fastening. The honeycomb wheel and more particularly each of the blades has a flexible end attached at least to the free edges of said blade, said flexible end being for example a flexible lip made of elastomer or rubber which rubs and is in contact against the internal walls of the stator.

[0019] The free edges of a blade are defined by the edges of the blade which are not assembled or secured to the shaft; this concerns the free edge of the blade distal to the shaft and the lateral free edges of said blade extending from the shaft to the free edge of the blade distal to the shaft.

[0020] The flexible end of each blade protrudes from the blade from the edge of the blade distal to the shaft and from the lateral free edges of the blade.

[0021] That is to say that the dimensions of the honeycomb wheel without the flexible ends allow its insertion into the interior volume of the body without contact with the interior walls of the stator, and the dimensions of the honeycomb wheel with the flexible ends are greater than the dimensions of the interior volume of the body, the flexible ends of the blades coming into contact with the interior walls of the stator and deforming when the honeycomb wheel is placed in the body of the lock.

[0022] The flexible ends are thus deformed when the shaft and the blades are placed in the body of the lock, and they come to curve and rub against the interior walls of the stator when the shaft rotates in the body.

[0023] It is known that the flexible ends interfere with the walls of the stator over a height of two (2) to ten (10) millimeters.

[0024] The flexible ends of the blades are made of an elastomer material, for example rubber, and gradually wear until they no longer rub against the walls of the stator, which causes one or more sealing defects. The worn flexible ends must then be replaced.

[0025] Significant interference increases the frictional forces and the torque required to rotate the shaft. Low interference reduces the seal and the barrier to flames and sparks.

[0026] The number of blades is chosen so that the two openings do not communicate directly with each other, at least one blade forming a watertight separating partition due to its flexible end.

[0027] In the case of a regular distribution of the blades on the shaft, it is known to have a rotary air lock comprising at least five (5) blades up to ten (10) blades, or even more.

[0028] A reduced number of blades allows for larger openings, and allows more air and material to be transported into a cell.

[0029] However, a reduced number of blades has the disadvantage that the sealing between the successive zones is only ensured by a watertight separating partition formed by a blade with its flexible end. In the event of a fault on a blade, a spark or flames can be transmitted from one zone to another.

[0030] This is all the more true since there may be impurities or pieces of compact and hard materials stuck between the inner wall of the stator and the flexible end of the single intermediate blade forming a sealed separating partition, degrading the seal by lifting, cracking or notching the flexible end, in particular if this flexible end is in the form of a flexible lip, as taught in the description of document DE102009015434A1. The impurities, depending on the particle sizes of the materials to be transferred, may have dimensions of between five (5) and ten (10) millimeters.

[0031] Furthermore, a flexible lip may deform under the action of the overpressure accompanying the sparks or the flame.

[0032] The first rotary air locks initially had a reduced number of blades, namely five (5).

[0033] Following explosions in installations, obtaining ATEX certifications currently requires achieving higher values of pressure barrier as well as flame and spark barrier.

[0034] A rotary air lock is usually expected to be a barrier between two zones having a pressure difference close to 0.35 bars, or approximately 35.103 Pa in the event of an explosion, tested according to a test protocol defined by standard NF EN 15089.

[0035] To meet these requirements, it was imagined to increase the number of blades up to ten (10), to ensure at least two separating partitions between the two openings, six (6) blades allowing to have two partitions.

[0036] Thus, if a partition is not completely watertight, the following cell allows part of the suppression to be absorbed and constitutes a volume to be crossed by the flame and the spark before reaching the following partition which the flame and the sparks will also have to cross before being able to reach the following zone. This increases the watertightness ensured by the lock.

[0037] A lock with six blades has just passable flame barrier and pressure barrier performance, which is why locks commonly have eight (8), nine (9) or even more blades.

[0038] This solution of increasing the number of blades, however, has several drawbacks.

[0039] The flow rate of the lock is essentially determined by the volume of the cells and the rotation speed of the cell wheel, as well as the dimensions of the openings of the lock.

[0040] Therefore, using a large number of blades makes the cells of the honeycomb wheel smaller.

[0041] A reduction in the material transport flow rate due to smaller cells is not sought, for obvious reasons of performance and profitability of the installation.

[0042] A greater number of blades also implies an increase in the weight of the honeycomb wheel, and therefore a more resistant shaft and greater energy consumption to rotate said honeycomb wheel in the stator.

[0043] To transport the same amount of material at a constant rotational speed, the size of the rotary air lock must then be increased, making it more cumbersome and more expensive. This also requires a larger diameter shaft, which further reduces the volume of the cells.

[0044] Another solution is an increase in the rotation speed to increase the flow rate of the rotary air lock, but this increases the amount of energy required to operate the lock and therefore the installation, which is economically expensive.

[0045] Increasing the speed also has the disadvantages of increasing friction and therefore wear of the parts in contact, and of increasing the forces of the motors which requires oversizing the lock and increases its energy consumption.

[0046] Increasing the speed has an additional disadvantage in that the airlock acts like a fan, whereby rotating the blades too quickly can fan flames and sparks and increase the chances that still-incandescent or flaming particles will be transmitted by the simple rotation of the airlock before they are extinguished. Furthermore, increasing the speed of rotation of the blades means that the time that sparks and flames are held in a cell is reduced, which increases the chances that still-incandescent or flaming particles will be transmitted by the simple rotation of the airlock before they are extinguished.

[0047] Nowadays, the aim is to create the most energy-efficient installation possible, which limits the possibilities of oversizing the lock.

[0048] Furthermore, these solutions do not solve the problem of degradation or lifting of the flexible lip of the blades allowing the passage of a spark or a flame, or causing air leaks.

[0049] In addition, multiplying the number of blades requires reducing the dimensions of the airlock openings, which reduces the flow rate. In addition, multiplying the number of blades disrupts the evacuation of the material passing through the air lock, in particular the most less dense, and cause material blockages, particularly upstream of the air lock, which causes production stoppages.

[0050] Document DE102019100198A1 and document DE102009015434A1 cited above teach a rotary air lock comprising blades having at their end a flexible end which rubs against the stator. On the front of the blade in the direction of rotation of the shaft of the lock is installed a deflector made of a hard material such as metal which can grind coarser particles in the material to be transported.

[0051] Thus, coarse components in the bulk material can be crushed or blocked by this baffle, so that wear on the flexible end is reduced.

[0052] This solution makes it possible to limit the problem of degradation of the flexible end by large impurities.

[0053] This solution, however, has the disadvantage of not preventing the flexible end from deforming or lifting due to an impurity, allowing the passage of a spark or a flame, or causing an air leak. It is therefore necessary to multiply the number of blades as indicated above to more than eight (8) blades, or even ten (10), which makes the lock expensive to manufacture.

[0054] In addition, this configuration requires additional and therefore costly maintenance of the deflectors in addition to the flexible ends.

[0055] Document DE102019100198A1 further teaches that the flexible end can be formed from two plates pressed against each other acting as juxtaposed lips.

[0056] The front plate in the direction of rotation of the lock shaft is made of an elastically deformable material, for example a soft or semi-hard plastic or rubber, and the second plate arranged behind it has a stabilizing effect and is made of a harder plastic or composite material, preferably with a textile reinforcement.

[0057] This additional feature provides greater pressure resistance, but increases friction and complicates maintenance due to the multiplicity of plates. Furthermore, the disadvantage remains of not preventing deformation or lifting of the flexible end due to an impurity, allowing the passage of a spark or flame, or causing an air leak.

[0058] In summary, the lessons of the state of the art do not offer a satisfactory solution in terms of security performance and cost.

[0059] It is therefore the object of the present invention to create an improved rotary air lock, having an improved flame barrier function and an improved pressure barrier function, while allowing a transfer of material from one zone to another with a satisfactory flow rate.

[0060] Another objective of the invention is to propose a rotary air lock capable of being sealed when subjected to a pressure difference between two zones of at least 0.35 bars, or substantially 35.103 Pa in the event of an explosion and in operation, tested according to a test protocol defined by standard NF EN 15089, or even at least 0.5 bars, or substantially 5.104 Pa.

[0061] Another objective of the invention is to provide a rotary air lock of simple design, robust, economical to manufacture, easy to manufacture and maintain.

[0062] Another objective of the invention is to provide a compact rotary air lock, having reasonable operating energy consumption.

[0063] Another objective of the invention is to provide a versatile rotary air lock, which can be used in different installations involving the transfer of materials which can cause explosions.

[0064] Another objective of the invention is to propose an installation implementing a transfer of material capable of causing explosions, comprising at least one such rotating air lock.

[0065] To this end, the invention relates to a rotary air lock, comprising a cylindrical body whose inner walls form a stator in which is mounted a honeycomb wheel capable of being driven in rotation, said honeycomb wheel comprising a transverse shaft from which rigid blades extend radially and regularly, each having on its free edges, on the front face, a sealing element between the honeycomb wheel and the stator.

[0066] Advantageously, each of the blades of the rotary air lock comprises on its free edges, on the rear face, a rear sealing element between the honeycomb wheel and the stator, the two front and rear sealing elements, the edges of the free edges of each blade delimiting an intermediate chamber.

[0067] Each intermediate chamber allows two sealing elements on either side of a blade to deform independently of each other.

[0068] Each front sealing element and rear sealing element of a blade comprises a section distal to the shaft and two lateral sections respectively facing the lateral free edges of said blade, protruding from said blade and rubbing against the walls of the stator when the honeycomb wheel is installed and rotates in the stator.

[0069] Each intermediate chamber has a part distal to the shaft, and two lateral parts facing the lateral edges of the corresponding blade.

[0070] Each intermediate chamber formed on the one hand by the two sealing elements of the same blade, and on the other hand by the edges of said same blades constitutes a volume to be crossed by the flames and sparks, just like the cells.

[0071] If an impurity lifts a sealing element of a blade, the other sealing element of said blade is sufficiently spaced by the intermediate chamber so as not to be lifted, which limits air leaks and the passage of sparks or flames.

[0072] The intermediate chambers with a thickness of one blade are narrow and do not significantly reduce the volume of the cells, the chambers being the thickness of the edges of the blade.

[0073] The term narrow denotes a gap configured to allow deformation of a first sealing element under the action of overpressure or an explosion, allowing passage of air, spark or flame between a cell and the intermediate chamber, without contact of said first sealing element with the second sealing element of the same blade.

[0074] By the term narrow, we can designate according to a second embodiment of the invention a spacing configured to allow: - firstly, a deformation of a first sealing element under the action of overpressure or an explosion, allowing the passage of air, spark or flame between a cell and the intermediate chamber, without contact between said first sealing element and the second sealing element of the same blade, - secondly, a balancing of the pressure between the cell and the intermediate chamber, - in a third stage, deformation of the second sealing element by deformation and pressing of the first sealing element against the second sealing element, allowing passage of air, spark or flame between the intermediate chamber and the following cell.

[0075] In this second embodiment of the invention, it can be noted that the bearing surface for deforming the first sealing element in the first step is identical to the bearing surface for deforming the first and second sealing elements at the same time during the third step. The force to be exerted to deform the first and second sealing elements at the same time during the third step is therefore greater than the force to be exerted to deform the first sealing element alone. The barrier function is improved.

[0076] This configuration makes it possible to simply multiply the number of partitions while limiting the number of blades, the partitions being formed from sets of front sealing elements and the associated blade, and from sets of rear sealing elements and the associated blade, spaced either by an intermediate chamber or a cell.

[0077] It is therefore not necessary to increase the number of blades to increase the pressure barrier function to the detriment of the volume of the cells.

[0078] The design of a rotary air lock according to the invention is close to that of a rotary air lock according to the prior art, with a reduced number of blades, while providing a barrier to pressure, flames and sparks similar to a lock which would have twice as many blades.

[0079] The modifications made are inexpensive to carry out, without major additional maintenance constraints, and the lock according to the invention remains compact and inexpensive to manufacture.

[0080] The rotary air lock according to the invention thus has an improved flame barrier function and an improved pressure barrier function, while allowing a transfer of material from one zone to another with a satisfactory flow rate.

[0081] According to a preferred characteristic of the invention, the front sealing elements and the rear sealing elements are identical.

[0082] This allows for standardization of the parts used in manufacturing the rotary air lock, further reducing manufacturing costs and simplifying maintenance.

[0083] According to a preferred characteristic of the invention, the front and rear sealing elements of the same blade are interposed securely between said blade and respectively front and rear rigid strips.

[0084] The sealing elements are thus held securely to the blade in a simple and reversible manner, which simplifies maintenance. The rigid strips may be in the form of a perforated plate or not, possibly in the form of a rigid U-shaped strip to limit the weight, the ends of the U-shaped strip being proximal to the shaft. The rigid strips may be screwed or bolted to the blade, screws passing through the sealing elements.

[0085] According to a preferred characteristic of the invention, the front and rear sealing elements are flexible sheets of elastomer and / or thermoplastic material, in particular canvas.

[0086] This makes it possible to simplify the manufacture of the sealing elements. It is thus possible to cut said sealing elements from a roll of elastomeric and / or thermoplastic material, whether canvas-covered or not.

[0087] According to a preferred characteristic of the invention, the flexible sheets are made of abrasion-resistant natural canvas rubber.

[0088] This material in fact has characteristics of abrasion resistance and responsiveness which are particularly suitable for manufacturing sealing elements.

[0089] According to a preferred characteristic of the invention, the intermediate chamber of each blade comprises at least one flap valve opening into at least one cell preceding and / or following said blade when said valve is open.

[0090] This makes it possible to avoid damaging the sealing elements by providing a deformable element preferentially at a defined overpressure value, to avoid damaging the lock in the event of overpressure caused by an explosion.

[0091] The presence of a flap valve towards the front cell and towards the rear cell makes it possible to manage respectively an explosion and an associated overpressure in the zone preceding the lock, or in the zone following the lock.

[0092] According to a preferred characteristic of the invention, each intermediate chamber comprises at least one extinguishing channel.

[0093] This creates a path for the sparks and / or flames to travel, thereby increasing the chances of them going out, thereby limiting their transmission to the next cell.

[0094] By positioning a flap valve and an extinguishing channel, it is thus possible in the event of an explosion to be able to manage on the one hand the overpressure and on the other hand the sparks and flames while limiting the damage to the lock, avoiding its replacement and limiting the costs of corrective maintenance to be implemented following an explosion.

[0095] According to a preferred characteristic of the invention, the valve(s) of the at least one valve is / are formed by one or more portions of the front and / or rear sealing elements facing the lateral free edges of the blades and proximal to the shaft.

[0096] According to a preferred characteristic of the invention, the extinguishing channels are formed by lateral parts of the intermediate chambers facing the lateral free edges of the blades.

[0097] In fact, it has been found by this configuration that during explosion tests of a lock having these characteristics, at the level of a blade forming a partition, the air and the flames deform and pass at the level of a section of a sealing element distal to the shaft of said blade, but that the flames and the air follow a lateral part of the intermediate chamber forming an extinguishing channel to a portion of the other sealing element of said blade, which lifts in the manner of a valve flap and allows air to pass. The flames and sparks surprisingly do not come out through this valve.

[0098] The tests carried out have shown that a lock according to this configuration is a barrier between two zones presenting a pressure difference in the event of an explosion and in operation of at least 0.35 bars, or approximately 35.103 Pa, tested according to a test protocol defined by standard NF EN 15089. Such a lock therefore presents an improved flame barrier function and an improved pressure barrier function, while allowing a transfer of material from one zone to another with a satisfactory flow rate, with a pressure difference on either side of the lock of 0.35 bars, or approximately 35.103 Pa, or even more in the event of an explosion and in operation.

[0099] According to a preferred characteristic of the invention, the rotary air lock comprises on each blade a metal plate in front of the front sealing element, forming a deflector and / or grinding knife.

[0100] This makes it possible to grind and / or prevent excessively large impurities from damaging the sealing elements.

[0101] According to a preferred characteristic of the invention, the rotary air lock comprises six blades.

[0102] Tests have shown that a lock according to the invention with six blades is a barrier between two zones having a pressure difference of at least 0.5 bars, or substantially 5.104 Pa, preferably at least 0.6 bars, or substantially 6.104 Pa or even more, in the event of an explosion, tested according to a test protocol defined by standard NF EN 15089.

[0103] A six-blade lock according to the invention remains simple and economical to manufacture, compact, easy to maintain, and ensures a high-performance barrier.

[0104] The invention also relates to an installation implementing a transfer of material which can cause explosions, including in particular industrial dust removal and filtration of industrial processes, ventilation and centralized suction, or pneumatic transfer comprising at least one rotary air lock described above.

[0105] Other aims and advantages of the present invention will appear during the description which follows with reference to the attached drawings illustrating an exemplary embodiment of the invention and in which:

[0106] [Fig. 1] is a partial schematic front perspective view of a rotary air lock according to one embodiment of the invention, excluding the left side wall of the lock body.

[0107] [Fig.2] is a schematic view seen from the left side of the interior of the air lock rotary of [Fig.l] without the side walls of the stator, with a schematic representation above the lock of a zone for transporting and storing flammable materials preceding the lock, and below the lock of a zone for transporting and storing flammable materials following the lock.

[0108] [Fig.3] is a schematic front perspective view of the honeycomb wheel of the [Fig.l] alone.

[0109] [Fig.4] is a schematic perspective detail view of the honeycomb wheel and stator of the lock of [Fig.l], the blades having another angle of rotation, showing a blade without a rear sealing element.

[0110] [Fig.5] is a schematic side and detail view of the lock of [Fig.2], having a blade with a rear sealing element deformed at a section distal to the shaft of the alveolar wheel, under the action of overpressure.

[0111] [Fig.6] is a schematic side and detail view of the lock of [Fig.2], having a blade with a rear sealing element deformed at a section distal to the shaft of the alveolar wheel, under the action of overpressure and having a deformation of a portion of the front sealing elements opposite the lateral free edges of the blades and proximal to the shaft, said portion forming a valve flap.

[0112] The invention relates to a rotary air lock 1, hereinafter referred to as "lock" 1.

[0113] This lock 1 comprises a transversely extending cylindrical body whose lateral and peripheral internal walls form a stator 2.

[0114] This lock comprises two openings which can extend laterally over the entire width of the stator, i.e. an inlet opening 10 which can be connected to a material supply zone which can cause explosions Z1, preferably above the lock, and an outlet opening 11 which can be connected to a material reception zone which can cause explosions Z2, preferably below the lock, as illustrated in [Fig.2].

[0115] A honeycomb wheel 3 is mounted transversely in the stator, able to pivot around a virtual axis AA' transverse to the lock 1 under the action of the drive of a motor 12 visible to the right of the lock 1 in [Fig.l].

[0116] With reference to the drawings, the lock is considered in its position of use.

[0117] Thus, the top of lock 1 is at the top of Figures 1 and 2, the bottom of the figures is at the bottom of Figures 1 and 2, the left of the lock is on the left of [Fig.l], and the right of the lock is on the right of [Fig.l].

[0118] The alveolar wheel comprises a shaft 30 transverse to the lock 1 which can pivot around the virtual axis AA', and rigid blades 4 extending radially and regularly from the shaft 30.

[0119] The blades 4 may be formed from a metal plate, in particular steel, the blades 4 may be made in one piece with the shaft 30, or assembled by welding to the shaft or by any other reversible or non-reversible means of attachment.

[0120] The honeycomb wheel 3 rotates in the stator 2 in a clockwise direction here illustrated by a dotted curved arrow in Figures 2 to 6, defining with respect to the direction of rotation a front face 40 of the blades 4 and a rear face 41 of the blades 4.

[0121] The length of the inlet 10 and outlet 11 openings of the lock 1 may correspond to the spacing between two blades 4, taken at their distal end to the shaft 30, as illustrated in [Fig.l], which makes it possible to limit blockages.

[0122] Each blade 4 has, in addition to a front face 40 and a rear face 41, free edges 42, 43, that is to say a free edge 42 distal to the shaft 30, and two lateral free edges 43 left and right.

[0123] The plate 4 has on each free edge 42, 43 respectively a distal edge 420 to the shaft 30, and a left and right lateral edge 430 of the same thickness.

[0124] When the honeycomb wheel 3 is mounted in the stator 2, the edges 420, 430 of the blades 4 are opposite the walls of the stator 2, at a defined interval, of the order of a few centimeters, in particular between 3 centimeters and 5 centimeters.

[0125] The lock 1 and in particular each blade 4 comprises a front sealing element 5 located on the front face 40 of said blade 4, and rubbing against the walls of the stator 2.

[0126] The lock 1 and in particular each blade 4 further comprises a rear sealing element 6 located on the rear face 41 of said blade 4, and coming to rub against the walls of the stator 2 and ensuring a seal between the alveolar wheel 3 and the walls of the stator 2.

[0127] In fact, the front sealing element 5 and the rear sealing element 6 protrude from each blade 4 distally to the shaft 30 and laterally by a distance additional to the interval defined between the edges 420, 430 of the blades 4 and the walls of the stator 2, said additional distance being between five (5) and twenty (20) millimeters. Tests have shown that an additional distance between six (6) and nine (9) millimeters corresponds to a satisfactory compromise in terms of sealing and friction.

[0128] The front sealing element 5 has a distal section 50 at the shaft 30, and two lateral sections 51 left and right respectively at the level of the distal free edge 42 and the lateral free edges 43 left and right of the blade 4.

[0129] The rear sealing element 6 has a distal section 60 at the shaft 30, and two lateral sections 61 left and right respectively at the level of the distal free edge 42 and the lateral free edges 43 left and right of the blade 4.

[0130] The slices 420, 430 of the free edges 42, 43 of each blade 4, the front sealing element 5 and the corresponding rear sealing element 6 define intermediate chambers 7. Each intermediate chamber 7 is open on its part distal to the shaft 30, opposite the walls of the stator 2 and the inlet 10 and outlet 11 openings according to the angular position of the honeycomb wheel 3.

[0131] It should be noted that the blades 4 with the corresponding sealing elements 5, 6 partition the volume of the rotor 2 which can receive air or material into small volume intermediate chambers 7, and into cells 31.

[0132] Each intermediate chamber 7 comprises a distal part 70 to the shaft 30 and two lateral parts 71 left and right.

[0133] The thickness of each intermediate chamber 7 corresponds to the thickness of the slices 420, 430 of the blade 4.

[0134] This thickness can be configured to allow deformation of a first sealing element 5, 6 of a blade 4 under the action of overpressure or an explosion, allowing passage of air, spark or flame between a cell 31 preceding said blade 4 and the intermediate chamber 7 of said blade 4, without contact of said first sealing element 5, 6 with the second sealing element 6, 5 of the same blade 4, as illustrated in [Fig.5].

[0135] According to a second embodiment of the invention, this thickness can be configured to allow: - initially a deformation of a first sealing element under the action of overpressure or an explosion, allowing a passage of air, spark or flame between a cell and the intermediate chamber, without contact of said first sealing element with the second sealing element of the same blade as illustrated in [Fig.5], - in a second step, a balancing of the pressure between the alveolus and the intercalary chamber, - in a third stage, a deformation of the second sealing element 6, 5 by deformation and pressing of the first sealing element 5, 6 against the second sealing element 6, 5, allowing a passage of air, spark or flame between the intermediate chamber 7 and the following cell 31.

[0136] In this second embodiment of the invention, it can be noted that the bearing surface for deforming the first sealing element 5, 6 in the first step is identical to the bearing surface for deforming the first 5, 6 and the second 6, 5 sealing element at the same time during the third step.

[0137] The first sealing element 5 and the second sealing element 6 may be identical, and each consist of a flexible sheet of elastomer and / or thermoplastic material, in particular canvas.

[0138] The material of the sealing elements may be antistatic, configured to prevent an accumulation of an electric charge which could cause a spark. Said material may meet the requirements of standard NF EN ISO 80079-36.

[0139] This flexible sheet may be made of a sealing material such as ethylene propylene diene rubber, polyvinyl chloride, polytetrafluoroethylene, polyester urethane rubber, silicone, fluorosilicone, with different levels of shore hardness, with a fabric insert and / or a coating.

[0140] This flexible sheet may in particular comprise a smooth face and a face reinforced with a fold of fabric, be made of vulcanized or unvulcanized natural rubber, or a mixture of vulcanized or unvulcanized natural rubber and synthetic elastomer.

[0141] The tests showed that a flexible sheet made of a material with a Shore A hardness of between 55 and 85 made it possible to obtain satisfactory results.

[0142] The tests showed that a flexible sheet made of a material with an abrasion value of between 70 and 100 mm3 under ION according to standard DIN 53516 made it possible to obtain satisfactory results.

[0143] The front sealing elements 5 and the rear sealing elements 6 of each blade 4 are interposed in a fixed but reversible manner between said blade 4 and respectively front and rear rigid strips 8, at the level of the free edges 42, 43 of the blade 4 and here along the shaft 30.

[0144] The rigid strips 8 are for example made of metal, and can be plates.

[0145] The rigid strips 8 can be screwed or bolted to the blade.

[0146] As illustrated in the figures, screws may pass through the front sealing elements 5, the rear sealing elements 6, the rigid strips 8 and the blades 4 to cooperate with nuts.

[0147] The rigid strips 8 can be positioned in line with the distal edges 420 of the shaft 3 of the blades 4, or be set back relative to the lateral edges 430 on all or part of the lateral free edges 43 of the blades 4 as illustrated in [Fig.4] for a functionality described below.

[0148] Each intermediate chamber 7 may comprise a flap valve capable of opening to open into a cell 31 in front or behind the blade 4 corresponding to said intermediate chamber 7 and blocking the opening in the other direction.

[0149] In fact, a valve of such a valve can be formed simply by a front or rear portion 510, 610 of a front or rear sealing element 5, 6 opposite a lateral free edge 43 of a blade 4 and proximal to the shaft 3. This portion 510, 610 forming a valve has a degree of ease of opening adjustable according to the withdrawal relative to the lateral edge 430 of all or part of the lateral free edge of the blade 4 of the rigid strip 8.

[0150] Said portion 510, 610 thus cooperates with the face 40, 41 of the corresponding blade 4 and the corresponding rigid strip 8 to form such a flap valve at low cost.

[0151] As illustrated in [Fig.6], the opening of the portion 510, 610 forming a valve can preferably be done near the shaft 3.

[0152] Each intermediate chamber 7 may comprise an extinction channel 710.

[0153] In fact, with regard to the production of a flap valve as described above, the lateral part 71 of the intermediate chamber 7 corresponding to the portions 510, 610 forming a flap forms an extinguishing channel.

[0154] Of course, each blade 4 may comprise a front / and / or rear flap valve according to another embodiment communicating the intermediate chamber 7 of said blade 4 towards the cell 31 following or preceding said blade 4 and blocking the passage in the other direction. Also, the flap valve can be connected to the intermediate chamber 7 by an extinguishing channel dug into the blade 4 or added.

[0155] The lock 1 may comprise on each blade 4 a metal plate in front of the front sealing element 5, forming a deflector and / or grinding knife.

[0156] According to another embodiment not illustrated here, the lock according to the invention may comprise only at least four blades (4), which is sufficient to ensure at least two separating partitions between the two zones Z1 and Z2.

[0157] It has been observed, however, that a lock according to the invention comprising six blades 4 presents a particularly advantageous compromise in terms of performance and cost.

[0158] A rotary air lock according to the invention comprising a shaft of fifty (50) millimeters in diameter, six (6) blades 4 of eight (8) millimeters in thickness, sealing elements 5,6 of eight and a half millimeters (8.5 millimeters) in thickness and extending from tent (30) to forty (40) millimeters beyond the blades 4, was tested according to a test protocol defined by standard NF EN 15089.

[0159] This lock has received an EU ATEX type examination certificate, allowing its installation in zone 20, for an STI material with a rotation of the alveolar wheel at nineteen (19) revolutions per minute and a pressure difference between the supply and reception zones of 0.6 bars, which corresponds to a relative pressure or depression of 6.104Pa.

[0160] The invention finally relates to an installation implementing a transfer of material which can cause explosions, including in particular industrial dust removal and filtration of industrial processes, ventilation and centralized suction, or pneumatic transfer. This installation comprises at least one rotary air lock having all or part of the characteristics of the lock 1 described above.

Claims

Claims

1. Rotary air lock (1), comprising a cylindrical body whose inner walls form a stator (2) in which is mounted a honeycomb wheel (3) which can be driven in rotation, said honeycomb wheel (3) comprising a transverse shaft (30) from which rigid blades (4) extend radially and regularly, each having on its free edges (42, 43), on the front face (40), a sealing element (5) between the honeycomb wheel (3) and the stator (2), and, on the rear face (41), a rear sealing element (6) between the honeycomb wheel (3) and the stator (2), the two front and rear sealing elements (5, 6) and the edges (420, 430) of the free edges (42, 43) of each blade (4) delimiting an intermediate chamber (7), characterized in that the front sealing elements (5) and the rear sealing elements are identical (6),and in that the intermediate chamber (7) of each blade (4) comprises at least one flap valve opening into at least one cell (31) preceding and / or following said blade (4) when said valve is open.,

2. Rotary air lock (1) according to claim 1, characterized in that the front and rear sealing elements (5, 6) of the same blade (4) are interposed securely between said blade (4) and respectively front and rear rigid strips (8).

3. Rotary air lock (1) according to one of claims 1 or 2, characterized in that the front and rear sealing elements (5, 6) are flexible sheets of elastomeric and / or thermoplastic material, in particular canvas.

4. Rotary air lock (1) according to claim 3, characterized in that the flexible sheets are made of abrasion-resistant canvas natural rubber.

5. Rotary air lock (1) according to claim 4, characterized in that each intermediate chamber (7) comprises at least one extinguishing channel (710).

6. Rotary air lock (1) according to claim 5, characterized in that the flap(s) of the at least one valve is / are formed by one or more portions (510, 610) of the front and / or rear sealing elements facing the lateral free edges (43) of the blades (4) and proximal / proximal to the shaft (30).

7. Rotary air lock (1) according to claim 6, characterized in that the extinguishing channels (710) are formed by lateral parts (71) of the intermediate chambers (7) facing the lateral free edges (43) of the blades (4).

8. Rotary air lock (1) according to one of claims 1 to 7, characterized in that it comprises on each blade (4) a metal plate in front of the front sealing element, forming a deflector and / or grinding knife.

9. Rotary air lock (1) according to one of claims 1 to 8, characterized in that it comprises six blades (4).

10. Installation implementing a transfer of material which can cause explosions, including in particular industrial dust removal and filtration of industrial processes, ventilation and centralized suction, or pneumatic transfer, characterized in that said installation comprises at least one rotary air lock having the characteristics of a rotary lock (1) according to one of claims 1 to 9.

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