FR2473348A2 - Contaminated air filters in removable containers - remotely clamped to air system ducts esp. of processing plant for nuclear installations - Google Patents

Abstract

The parent patent describes filter elements comprising changing equipment and contamination protection housed in waste storage vessels and intended for the sepn. of toxic, esp. radioactive dust from breathing air and process air. In this addition, one filter plant consists of two series-connected standard waste containers(2), of 200 or 400 litre capacity. One container comprises a single-stage or two-stage granular or sand bed filter while the other comprises a suspended solids filter. The two containers are connected by a closable air duct(25) joining together their two removable hoods(36,40). Each container has a separate central pipe with its own valve(34,42) for inlet and outlet respectively of air, connected to wedge- shaped or tapering feed and return ducts(37,43). The containers (2) together with their incorporated filters are each clamped to the top hoods or covers(36,40) at four points by lever- actuated clamping systems (not illustrated in detail); these clamping systems are remotely operated or can be tightened or released by hand. Used partic. for the various decontamination processes involved in the dismantling of nuclear power plants and the like when they are no longer required.

Description

The main patent describes a filter element with exchange and protection devices against contamination, mounted in waste containers and arranged to separate substances harmful to health from the air intended for the respiration or other processes in aeration facilities used, for example, for nuclear technology.

In accordance with this patent, filter layers made of filter paper or granular material, in the form of plates, blocks, parallelepipeds, are reported in standard containers of 200 or 400 liters and without any external modification thereof. , discs, rings, stars or zigzags.

 In addition, these containers each have a removable lid in the form of a cap, as well as air inlet and outlet tubes suitable for being connected to upper pipes for clean air and dusty air.

Transparent protective sleeves can be mounted on peripheral edges with multiple grooves provided on the cover and the container to ensure maintenance without risk of contamination and to allow the exchange of exhausted containers.

 In another embodiment according to the main patent, the cap-shaped lids of the waste containers or filter drums are provided with remote control elements, the role of which is either to release the container from the seals with the filter which is incorporated, after closing the valves, or to tighten in place a new container to connect it to the air supply pipe.

Other problems arise during the decommissioning and demolition of nuclear reactors which have ceased to be usable
The lack of profitability, the end of useful life or the irreversible consequences of an operating accident sometimes constitute the reasons for demolition which justify such an unusual decision.

The establishment of a satisfactory nuclear installation from the point of view of maintenance, repair and peace of mind has led in recent years to a number of conditions concerning new constructions.

During the demolition of radioactive remains until reaching what can be called a green meadow, there are bound to be difficult environmental problems
None of the final phases of shutdown of a reactor is simultaneously linked to the cessation of radioactivity. This is accumulated for years in the materials of the hot zone of the reactor.

This is so - to cite only a few examples - of the wall of the vessel which contains the core as well as of the various fittings, pipes, pumps and boilers on which radioactive deposits have accumulated. Even the concrete covering which constitutes the biological screen is partly concerned in this regard.

The complete demolition of a nuclear reactor implies that before their transport, all contaminated metal or concrete parts are shredded so that they can be packed away from any contamination.

The dismantling of so-called hot residues, however, does not go through any problem. Research carried out in the United States concerning the technique of demolition has made it possible to resolve the question, then still debated, of knowing how such an operation can be ensured.

The technique of cutting by plasma torch devices in cells with high air exchange, or by means of mobile devices, gives more advantages to dry demolition than to grinding in a humid environment. The secondary problem of getting rid of the contaminated liquid can only complicate the process.

When cutting the reactor parts, in particular those of stainless steel, with a plasma torch, finely dispersed fusion fumes of high density and concentration appear. The same applies to the flame cutting of reinforced concrete and steel parts. Large fumes of calcined concrete must be mixed with the fumes from the oxidation of metals, the dust concentration in the air being able to range from 1 to 2 g / m3 with a particle size of 0.03 to 30 microns. Other difficulties appear during burning due to sparks or incandescent remains which fly in the air, all linked to the question of the high temperatures used and which pose difficulties in the case of aluminum oxide particles. .

With medium contamination dust, we count on a radioactive charge of 1 curie per kilogram of it. In addition, a central accumulation of, for example, more than 400 g of dust in the area with high radioactivity is not possible since, for safety reasons, one should not exceed 10 millirems at a distance of 1 meter. .

 From the point of view of the filtration technique the problem which arises consists in eliminating from the exhaust air the dangerous substances by their emission, so as to minimize the risks for the environment. The importance of pollution necessarily decreases when the path necessary for this separation of dust is shortened from the cutting or dividing points to the waste container and from there to the final disposal site.

 The types of filters which have been proposed so far for the application in question require too much apparatus and are therefore of an exaggerated cost price. The numerous intermediate positions between the point of appearance of the dust and the receptacles intended to receive them, with the long transport path until their discharge into the standardized waste containers involve high risks and can only be suitable if takes into account the above-mentioned difficulties, such as arise when using electric filters or filter bags, or combinations of high-efficiency cyclones with fine filters located downstream.

 The present addition is in principle based on the same problem as the main patent, namely to establish waste containers applied by clamping mechanisms against suitable pipes and in which are arranged filter elements suitable for separating from the air the substances hazardous to health, all in such a way that once these filters are saturated, they can be brought directly to the final repository, without additional operation, more particularly in the case of heavy contamination of the dust.

The present addition constitutes a subsequent embodiment of the invention according to the main patent. It consists in establishing a filtration installation by means of two standardized type waste containers, with a capacity of 200 or 400 liters, arranged one after the other and containing a bed. filter incorporated in one or two stages, made of divided dobby or sand, as well as another provided for suspended substances, these two containers being connected to each other for the flow of air, by The intermediate of removable cap lids shaped for the flow of air and through closable connecting pipes, axial tubes, also closable, which protrude from these lids by being fixed permanently by lateral fittings to pipes for the supply of dusty air (or polluted air) and purified air, with oblique walls, arranged side by side above these lids, while each container with the filter incorporated therein is applied against the cover corresponding to four lateral points by s elastic clamping mechanisms with levers, controlled by hand or by remote control, all of which can be released from this cover.

According to another embodiment of the invention the pre-filter disposed in the first container has a horizontal upper perforated wall extending over the entire section thereof and another arranged at a certain distance from the bottom of the container. Between these two walls and a central tube or air supply tube disposed along the axis of the container and provided with a tilting closure valve, is disposed a porous divided layer traversed from bottom to top by the polluted air. to absorb the dangerous substances it contains, this layer being made, for example, of fractional homogeneous grinding sand. The space provided between the lower perforated wall and the bottom of the container can if necessary also be filled with a divided material coarse-grained through which the polluted air must pass before coming into contact with the pre-filter and from there reaching the second container via the cover and the connecting pipes to the shut-off valve. It then flows from the outside to the inside through the filter for suspended substances that the second container encloses and rises through the central tube of the cover to reach the outlet pipe.

 According to another advantageous embodiment, the waste container which provides the pre-filtration and with which is associated a cover in the form of a cap provided with closable tubing and a central tube equipped with a rotating valve, itself contains an intermediate container. disposed in its center, filled for example with a grain material crossed from top to bottom by the polluted air. This container defines with the wall of the container an annular space used for the evacuation of pre-filtered air.

It also comprises two horizontal perforated upper and lower walls, in the form of discs which extend over its entire section to determine at the top, relative to the opening lid of the container, and at the bottom, relative to the bottom of the container. , spaces that. like that surrounding the fine star-shaped filter of the downstream container, can in the case of a strong contamination of the collected dust, be filled from the top with a self-hardening liquid protective medium, such as concrete, as well as the annular space formed between the side walls of the container and the intermediate container.

The present addition further solves the problem posed above in that the pre-filtration waste container is provided with two vertical cylindrical perforated walls arranged one inside the other, full at the top and closed by a lid, l the intermediate space being filled with divided matter. These walls define a porous central tube inside and outside a void space surrounded by the wall of the container. The pre-purified air which comes from top to bottom of the supply pipe, has passed through the aforementioned tube and the material itself, depending on its thickness and length, can then flow upwards towards the cap, then pass from there through the closable connecting pipes to reach the cover of the second container containing the filter for suspended substances, with a view to undergoing its final purification. It flows in this filter from the outside to the inside and passes through a central closable tube to evacuate through the starting pipe.

 In another important embodiment, the pre-filtration container filled with grain material contains a central tube and three perforated walls in the form of discs extending over its entire section to divide its interior into two cylindrical halves filled for example with classified sand of different granulations than the air coming from the cover from the polluted air pipe, crosses from top to bottom one after the other until reaching the space formed between the lower perforated wall and the bottom of the container. It flows from there through the central tube which crosses the aforementioned supply pipe, thus arriving at the start pipe arranged above the latter.

According to another embodiment, the pre-filtration container is provided with an intermediate container through which the polluted air passes from top to bottom, this container forming an annular space with the wall of the container, while its own internal space is equipped with three circular perforated walls which divide it into two halves filled with fractions of sand whose fineness increases in the direction of air flow. The lower perforated wall, relative to the bottom of the container on the one hand, and that upper, relative to the opening lid of the container on the other hand, provide spaces through which the air coming from an upper supply pipe passes through a central tube with oblique sealing flange, then passes vertically through the two layers superimposed filters and then flows in the pre-purified state through the annular space located between the side walls of the container and the intermediate container. It thus arrives at the cover and is evacuated from there via the starting pipe.

 Finally in yet another embodiment the container loaded with divided material, for example porous grinding sand or an activated contact agent, comprises a vertical separating partition passing exactly by its axis and which separates a coarse layer of a thinner layer, while upper and lower perforated walls inclined in the shape of a roof delimit the spaces corresponding to these fillings. The polluted air then crosses the coarse-grained layer from top to bottom, then from the bottom to the fine-grained layer. For this purpose, the lid tightened on the container in a removable manner, comprises separate inlet and outlet pipes and both of them closable, which in turn open into inlet and outlet pipes arranged therein. one next to the other.

 To completely solve the problem, the pre-filtration container can be further divided by at least three vertical cylindrical partitions arranged concentrically one inside the other and partially full at the top. These partitions determine between them two annular spaces which follow one another in the direction of flow and which are filled with divided materials of different granulations. The polluted air arrives in the container from the upper supply pipe by a central tube which crosses the cap; it flows horizontally in contact with the successive filter layers and it is evacuated from the container by the external space formed between the perforated walls # and the side wall of the latter, then by the cap and finally by the outlet pipe located above the latter.

 According to another characteristic of the addition, to ensure the seal between the flange of the cover and that of the prefiltration container, a lever clamping mechanism is used which acts on hooks provided with elastic washers, by means of two shafts carried in rotation by the cover and on which are mounted two-arm levers to which the hooks are coupled. On the operator's side, these levers are articulated to connecting rods or right and left connecting rods, coupled at their ends opposite to an asymmetric scissor device with four diamond-shaped rods on which a pneumatic cylinder acts. hydraulic which, at the end of its travel, brings these connecting rods to neutral point of unstable equilibrium, so that the jack does not have to act constantly during the operation of the filter.

According to a variant, the clamping mechanism provided between the cover and the container comprises two rods or connecting rods actuated by a vertical threaded rod-mounted for rotation between two bearings, this rod being able to be driven by a ratchet wrench or by a motor with eccentric and the sink. The rotation of the rod moves up or down a threaded sleeve mounted on it and to which the connecting rods are coupled by one end, the other being articulated to a lever. It is thus possible to order four elastic clamping hooks, the arrangement being such that the connecting rods are brought to the horizontal position which corresponds to the dead center of unstable equilibrium; the assembly is then blocked without the control members having to act.

In another embodiment, the clamping mechanism intended to apply the container against the cover comprises a sleeve forming a winch with right and left threads and median latching teeth capable of being actuated by means of a lever or by a jack. proceeding by impulses. In this sleeve engage two threaded rods, respectively right and left, the opposite ends of which are articulated to the levers for actuating the hooks to enable the container to be clamped in position irreversibly or, on the contrary, to release it.

The entire container can also be lifted and applied against the cover by means of a scissor mechanism platform, provided at a fixed position on the ground or, on the contrary, carried by a mobile carriage mounted on wheels. The mechanism itself comprises a central screw of known type with the corresponding sleeves or nuts to which the levers are articulated. The screw can be maneuvered using a ratchet or an automatic device. In the case of a rolling chassis
or cart, the wheels of the latter are then centered in depressions provided in the ground.

 A mobile filtration installation can include two containers, a fan and a suction hose with connection. The pre-filter enclosed by the first container can be established in one or two stages by means of coarse grinding sand or fine basalt or lava sand, while the second container contains another contact or separation agent suitable for perfect filtration, for example a large surface filter for suspended substances, made of pleated paper in the form of discs, cartridges, stars or blocks.

The appended drawing, given by way of example, will allow a better understanding of the addition, the characteristics which it presents and the advantages which it is likely to provide.
Fig. 1 shows in section in its entirety a combined two-stage installation comprising a sand filter and a filter for suspended substances, with the waste containers produced in the form of filter drums. The air inlet and outlet via the pipes located above the bonnet lids can be closed by tilting valves, while the connection pipes between the barrels are closed by a rotary valve. Arrival through the pre-filtration layer is carried out from the center and from top to bottom. #On the contrary in the next container the air passes from the outside to the inside through the filter cartridge
Fig. 2 is a perspective view illustrating the basic arrangement of the whole of a two-stage filtration installation, with the oblique-walled pipes ensuring the air intake and departure, and including the corresponding connections for eight filter drums or containers.

 It is shown in fig. 3 a two-stage filtration installation in which the pre-filter consists of a waste container enclosing an intermediate container with divided material, which comprises perforated upper and lower bottoms so that the air can pass vertically through the layer of filter material to drain laterally. The filter drum placed downstream contains a filter for suspended substances. All the closing devices capable of stopping the flow of air are constituted by rotary valves with a central axis.

 Fig. 4 shows another two-stage filtration installation in which the filter drum enclosed by the corresponding container is loaded with a layer of granular material, the intermediate container being porous on the outside and on the inside so that the air arriving from the center crosses this layer roughly horizontally to then escape from the annular space between this container and the outer container. The downstream filter barrel is for example constituted by a filter for suspended substances in the shape of a star or disc, made of paper folded in a zig-zag.

 Fig. 5 illustrates a two-stage divided material filter with upper air inlet and outlet pipes. The flow through the grinding sand shown by way of example is carried out firstly through a layer of coarse-grained material covered by a disk forming a perforated screen, then it passes through. another perforated separating disc to arrive at a downstream layer with fine granulation disposed between the previous one and a lower space. The purified air which leaves the abovementioned layers is evacuated from the container by a central tube and thus arrives at a starting pipe.

Fig. 6 shows a two-stage filter comprising a bed of sand divided inside a filter drum placed in the central part of a waste container. Three perforated sheets define two cylindrical spaces or filtration chambers charged with fractions of filter material of different granulations. The air arrives from the top and it first crosses the coarse layer, then the thin layer to then flow in a purified state between the inner barrel and the outer container in the direction of the top towards the starting pipe.

 We find in fig. 7 another variant of a two-stage filter barrel comprising a dividing partition arranged in the middle. The air arrives from above to pass through the chamber on the left which contains the coarse-grained material and then flows through the finer-grained layer enclosed by the chamber on the right. The waste container with which the filter is associated has inlet and outlet pipes with separate corresponding pipes.

 Fig. 8 shows a two-stage filter containing three perforated baskets which define there two filter chambers filled with sand or, if preferred, any other contact agent.

The two stages can act effectively in succession by using different separating agents. The air loaded with polluting substances must flow into the container from the inside to the outside in a horizontal path so that it can then escape from the empty space provided between the outer basket and the wall of the container.

Fig. 9 shows a lever clamping mechanism to clearly illustrate how the filter barrel, or respectively the waste container, can be energetically applied against the bonnet cover and the pipe attached thereto. Here the jack opens the scissors or articulated links located below it and to which it is connected.

It thus lowers the connecting rods or connecting rods by spreading them with the levers which are coupled to them, until the locking, clamping or elastic hooking devices lock the container to the lid, the blocking being ensured by passing from the unstable equilibrium dead center.

 Fig. 10 is a plan view corresponding to FIG. 9. It shows the chassis in profiled bars associated with the cap with the two actuation shafts and the fixing of the jack for a clamping device acting at four points.

 We can see in fig. 11 another clamping mechanism for filter barrel, comprising a vertical screw rotatably mounted and a threaded sleeve forming a nut on it Here the two rods or connecting rods with the shafts and the levers with two corresponding arms are articulated to the sleeve above mentionned. The actuation is ensured either by a motor with eccentric, or by a jack or more simply by a reversible ratchet wrench.

 Fig. 12 shows a clamping mechanism for filter barrel consisting of a nut-shaped part comprising a ratchet device in the manner of a lifting winch. This nut controls two threaded rods with right and left pitch, which in turn irreversibly actuate the levers and elastic clamping hooks.

Illustrated in fig. 13 a clamping device for filter barrel constituted by a lifting plate mounted on the ground, permanently, or by a movable lifting carriage, but centered in depressions, this mechanism being able to be raised or lowered selectively by rotation of a threaded rod .

Fig. 14 is a perspective view of a complete mobile installation with two containers.

 Fig. 1 shows first of all the cross-section of the filtration principle in a two-stage filter installation 1.

 There are two waste containers 2 of standardized type which are optionally equipped with a layer 3 of divided material (debris) or a lining 4 forming a filter for suspended substances, these containers being connected by lids 5 in hat shape with two pipes 6 and 7 for air intake and departure.

 In these pipes are disposed tilting valves 8 which serve to close the air inlet and outlet of the containers 2 during their exchange after the filter has been saturated with dust.

The covers 5, integral with the pipes 6 and 7, are connected to each other by a tubing device 9 equipped with a rotary valve 10. The divided material filter shown plays in this case the role of a layer 3 pre-filtration and it is used more particularly among other things for the pre-separation of smoke particles, for example stainless steel, iron, alumina, or even those mixed with dust which come from molten concrete; this dust penetrates into the sand bed at a high temperature with the incandescent residues with which it is charged.

For this purpose the waste container 2, being in the form of a rectangular or cylindrical container of 200 or 400 liters, comprises at the top and at the bottom a perforated sheet 11 with corresponding profile, as well as a central tube d air inlet 12. The lower perforated sheet 11 determines with respect to the bottom 13 of the container an empty space 14.

 The layer or mass 3 provided between the sheets 11 is made, for example, of sand such as quartz, basalt or lava sand, suitably classified, or else sand of protective space with a large specific surface. This layer is traversed from bottom to top over its entire height by the air 15 loaded with dangerous substances (polluted air) and which arrives through the central tube 12. This air exits through the cover 5 of the first container and the tubing device or Connection 9 brings it into that of the second to make it pass from outside to inside the filter 4 for suspended substances. When necessary, it is possible to pour concrete into the air inlet and outlet spaces of the filter 4 of the second container 2. Similarly, the sand bed 3 of the first container or pre-filter 2 can receive by the top of the cement grout clean to form concrete.

Fig. 2 shows in perspective the whole of a two-stage filtration installation with eight filter drums. There have been arranged a succession of pairs of containers 2 associated with each other, the first forming a pre-filter and the second fine filter. The two containers of each pair are applied by clamping mechanisms 21 against lids secured to an oblique-walled channel 17 which a central partition 18 divides into a supply chamber and a departure chamber equipped with connection flanges 19 and 20, the air to be treated arriving laterally along 22 and the purified air leaving in the same direction, as indicated in 23.

 We can see in fig. 3 a two-stage filtration installation in which the waste container 2 is loaded with a mass 27 of divided material and contains an intermediate container with a full side wall and with upper and lower walls or bottom 26 made of perforated sheet.

The space 24 defined by the bottoms 26 is filled for example with a mass 27 with fine granulation forming a filtering layer which the air stream 28 crosses from top to bottom. Between the bottom bottom 26 of the intermediate container and that 29 of the container there is an empty space 30.

Similarly, between the upper bottom 26 of the container and the lid 31 with central opening of the latter, there is another space or chamber 32.

As for the annular space 33 which appears between the side wall of the intermediate container and that of the container 2, it is used for the flow of the filtered air. The air to be purified arrives from the upper supply pipe 37 and it reaches the mass 27 via the central tube 35 of the cap 36 by passing through the rotary valve 34 which this tube encloses.

At its exit from the pre-filter the air flows through the closable connector 25 to flow from top to bottom to the downstream filter with star filtering wall 38. It exits through central tubular space 39> then through the tube 41 equipped with the rotary valve 42 and disposed in the axis of the cover 40 in order to finally be discharged in the purified state by the starting pipe 43.

 In the case of high contamination, we find in this embodiment the possibility of isolating inside the containers the spaces or chambers 30, 32, 33 of the pre-filter, as well as those of the downstream filter at star paper 38, possibly filling it with concrete or other self-hardening liquid insulation material.

 Fig. 4 shows a two-stage filter drum with divided material pre-filter placed inside a waste container 2. There are two cylindrical perforated sheets 44 and 45 arranged standing concentrically one inside the other, l the intermediate space being filled with a mass 27 of divided material. Here the inlet air 28 arrives from top to bottom from the supply pipe 37 by the central tube 35 provided inside the cover 36, it passes horizontally through the filtering layer 27 and after remaining sufficiently in contact with this, it exits through the annular space 33 to arrive in the cover 36. The closable connection tubing device 25 then brings it into the final filter 46 provided inside the second container 2.The air refined which leaves this second filter 46 flows through the central tube 41 of the cover 40 to reach the starting pipe 43. The cylindrical sheets 44 and 45 have an opening cover 31 and their lateral faces 47 are somewhat covered at the top to avoid any untimely passage of air by the vacuum resulting from the contraction of the contact medium.

 Fig. 5 represents a pre-filtration drum with two filling layers 49 and 50 of different granulations arranged in two cylindrical chambers of the waste container 2 and delimited by three circular perforated sheets 48. Between the bottom 13 of the container and the lower perforated sheet 48 an empty space or chamber 30 is provided. The air 28 arrives from the pipe 52 passes from top to bottom the cover or cap 40 to arrive at the filter layers 49 and 50. After contact with the coarse grains 50, then those finer 49 , the purified air passes through the lower space 30 and flows from there through the central tube 51 in the upper starting pipe 53. The axial tube 54 of the cover 40 is tightly connected by oblique edges 55 to the edge or flange of the aforementioned tube 51 of the filter barrel of the waste container 2.

 In fig. 6 the container 2 again constitutes a two-stage filter barrel, an annular space 56 being established between the internal face of the wall of this container and that external of an intermediate container 57.

This container 57 is divided by three circular perforated sheets 48 into two cylindrical chambers filled with masses 49 and 50 of different granulations. The air to be treated 28 first flows from the upper pipe 53 through a central tube 54 which oblique edges 55 sealingly connect with the cover 58 of the intermediate container, to arrive at the filter itself. Between this cover 58 and the upper perforated sheet 48 is an empty space or chamber 59 in which the air is distributed. Then this air passes through the coarse layer 50 and the finer layer 49, to thus reach the lower space 30, it flows from there through the annular space 56 between the side walls of the container 2 and of the intermediate container 57, thus arrives at the cover 40 and escapes via the starting pipe 52.

 Fig. 7 illustrates another two-stage filter barrel comprising two filter layers 49 and 50 arranged one beside the other, being separated by a vertical partition 61 disposed in the middle of the container 2.

At the top and the bottom thereof are arranged perforated walls or bottoms 62 inclined with respect to the horizontal and forming a separating partition. The air to be treated 28 arrives from the left pipe 37, it first crosses the closable tube 60 and the coarse layer 50 situated below the latter, then it flows into the lower chamber 63 to penetrate into the layer finer filtering 49. From there the purified air flows through the closable tube 64 to escape through the outlet pipe 43.

Fig. 8 corresponds to another version of a two-stage filter drum. Here the waste container 2 contains three cylindrical perforated walls 65, 66, 67 mounted on a field concentrically one inside the other and which define there two chambers or filtration spaces respectively filled with a material 50 with coarse granulation and d 'Another 49 with finer granulation. The internal perforated wall 67 here constitutes the inlet tube for the air 28 to be purified coming from the upper pipe 53. After having passed through the coarse layer 50 first, then the thinner layer 49, this air leaves the container by the annular space 68 provided between the side wall of the container 2 and the outermost perforated wall 65; it finally crosses the cover or cap 40 to escape through the starting pipe 52.

Fig. 9 shows a clamping mechanism for the filter barrel corresponding to the waste container 2. The latter is actuated for example by a pneumatic or hydraulic cylinder 69, which acts on a system 70 of rods forming a diamond or scissors, which it repels downwards against a fixed point 75. The rods or connecting rods 71 on the right and on the left are thus displaced towards the outside and they in turn actuate the double levers or brackets 72 to which they are coupled.

These drive the application or tightening hooks 73 which are articulated to them by means of elastic washers 74. During this movement the container 2 is lifted and applied against the bonnet cover 40. The connecting rods 71 and the connecting rods or scissors 70 exceed the horizontal neutral position so that there is locking and that any return movement is impossible. The jack 69 is thus freed from any retaining force.

 Fig. 10 is the plan view corresponding to FIG. 9. It suffices to point out that the rotational movement of the two angled levers 72 situated on the front of the assembly are transmitted by two rotating shafts 77 to two other levers 72 provided on the rear, so that the elastic hooks clamping or application 73 are driven in synchronism. The shafts 77 are rotatably supported by irons 76 U-shaped and # fixed themselves to the cover 40 of the filter. The cylinder 75 is also mounted on this cover.

Fig. 11 illustrates another clamping mechanism for a filter barrel or container 2, in which the force transmitting element is constituted by a vertical screw or threaded rod carried in rotation by two bearings 80. This screw can be driven by a lever ratchet 81 or by a motor 82, with eccentric and lever. When it turns it raises or lowers a sleeve 83 playing the role of nut. It is to this sleeve that the connecting rods or connecting rods 79 are articulated which control the square levers 72 to bring them to the self-locking position to which the container 2 is applied in leaktight manner against the cover or cap 40 by the four points corresponding to the hooks 73. By passing the dead center of the connecting rods 79 it is obtained that the control mechanism is relieved of any retaining force. Thanks to the presence of the elastic washers, the clamping force always remains sufficient.

Fig. 12 indicates another possible embodiment of a clamping mechanism comprising two threaded rods 87 with opposite pitches, engaged in a corresponding sleeve 84 capable of being driven by a ratchet device 85 in the manner of a winch. The rods 87 separate the square levers 72, which results in the spring hooks 73 clamping the container 2 against the cover 40. Instead of using a ratchet lever, it is also possible to provide a jack 69 which provides the impulses needed.

In fig. 13 the waste container 2 of the filter barrel can be applied against the cover 40 of the assembly 1 by means of a clamping or lifting plate 88 permanently mounted in place and comprising a screw 89 with ratchet lever 90 which allows the container in question to be raised or lowered by means of levers 91 Instead of the plate 88, it is also possible to use a carriage 95 the wheels 93 of which replace the anchoring feet 92 of such a plate in a way. This trolley then serves at the same time as a transport vehicle and a container clamping mechanism. For this purpose, the exact positioning and maintenance of the lifting carriage 95 is ensured by providing in the ground, below the container 2, for example four semi-circular depressions 94 forming centering points. To actuate the mechanism of the plate 88 or of the carriage 95 it is advantageous to use, in addition to any other suitable command, the ratchet lever 90 mentioned above.

 Fig. 14 finally shows a movable two-stage filtration installation, of compact construction, equipped with a fan 96 and a suction sleeve 97. This installation comprises two waste containers 2, with pre-filter and fine filter, the first 3, 27, 49, 50 can be filled with coarse grinding sand, fine basalt or lava sand, arranged in two stages, or any other contact medium, while the second or downstream filter 4, 38 , 46 consists of discs, cartridges or blocks of suitably pleated filter paper.

The filtration systems proposed by this addition in addition to those described in the main patent ensure, despite their simplicity of apparatus, significant advantages from the point of view of safety.

 The possibility of separating hazardous compounds from air without an intermediate operating station, by the shortest route and where they can be packed in their final state for a long time, in complete safety from radiation, has not never carried out previously in this form in known constructions.

These waste containers, of international standardization transformed into filter drums without any external modification, also meet all the conditions allowing their application in the toxic or nuclear fields.

As a result of the favorable height in this respect of the containers, it is possible to establish filtering layers which, for capacities of 200 and 400 liters, are capable of reaching a dimension of 800 to 1000 mm of a granular or amorphous mass, which provides optimal efficiency. At the same time, thanks to the large volumes that these containers represent, it is possible to mount large-area filter papers, connected directly downstream of the pre-filters and which constitute with these and the air ducts a installation for complete filtration by itself.

As a divided material layer, natural fine sands or porous grinding sands can be used in the form of fine fractions of lava or basalt grains and the surface of these media can also be loaded with active substances. Consequently, the use of such filter barrels is particularly advantageous when it is necessary to separate very hot radioactive smoke particles, mixed with incandescent residues sucked directly from their source.

 The arrangement of the sand beds inside the containers can be carried out without problem along one or two stages, if necessary, by using different granulations with the incorporation of devices preventing their final mixing.

It is possible to carry out in the same way a lining in activated carbon or other contact medium.
The fact that each hat lid connects a waste container with the filter which it contains to an air duct and that, in addition, each lid has a connection tube with another adjacent container which also contains a filter and a connection with an air duct, it is possible to imagine any combination of multi-stage filtration installations.

 The various lever mechanisms with neutral passage, intended to ensure the connection between the covers and the filter drums and to provide a seal against air leaks, can be used with manual actuation as well as with remote control using the various cylinders proposed above. The units thus established are particularly suitable as mobile installations with filter drums, fan and suction handle.

The question of the greatest difference in pressure between two filter drums connected to each other, compared to # the expense of. higher power than that entails, does not arise in the technique of this system. In fact, in the areas of use envisaged, installations of this kind are not intended to last, but only to be used temporarily. For this reason, the safety of the filter should be put before the energy consumption of an installation which should only operate for a limited time.

 It should moreover be understood that the above description has been given only by way of example and that it in no way limits the field of addition from which one would not leave by replacing the execution details described by all other equivalents.

Claims (13)

 1. Filter elements with exchange devices and with protection against contamination, mounted in waste containers and suitable for separating dangerous substances from the air intended for respiration or other processes in the installations of aeration, in particular in applications to the nuclear technique, according to any one of the claims of the main patent, characterized in that a filtration installation (1) is constituted by two standardized waste containers of 200 or 400 liters arranged one after the other and which contain a sand or divided matter filter (3) and a filter (4) for suspended substances, these two containers being connected to each other by # removable cap covers (5) provided for guiding the air and by means of a connection tube device (9) with closure member (10), while for ensuring the arrival and air outlet, axial tubes (12) which protrude therefrom and which are separately closable by valves- (8), are fixed permanently to pipes with oblique walls (6 and 7) arranged above them and provided with lateral pipes (19, 20) polluted air inlet and filtered air outlet, the containers (2) with the filters (3 and 4) which they contain, which can be tightened against the covers (5) at four points, or be released from # these, by elastic mechanisms (21) with levers controlled remotely from a central station or actuated by hand.  2. Filter element according to claim 1, characterized in that the pre-filtration layer (27) mounted in a container (2) is disposed between an upper perforated sheet (26) extending horizontally over the entire section of the container, sheet. lower perforated (26) located at a certain distance from the bottom (29) thereof, and a central tube (35) or air supply tube, located in the container and equipped with a rotary valve (34 ), the air loaded with dangerous substances, passing from bottom to top this layer (27) made for example of homogeneous grinding sand fractionated, while the lower space (30) defined t between the perforated sheet (26) lower and the bottom (13) of the container can if necessary be filled with a coarse divided material which the polluted air (28) crosses before arriving in contact with the pre-filtration layer (27) to then pass through the cover and the connecting pipe (25), and arrive at the container (2) in which is placed the filter (38) for suspended substances which it crosses from the outside to the inside before discharging upwards through the closable central tube (41, 42) which passes through the cap (40) to arrive at the starting pipe (43).  3. Filter element according to any one of claims 1 and 2, characterized in that the container (2) for pre-filtration, covered with a bonnet cover (36) with a device for closable connecting tube (25) and a central tube (35) with a rotary shutter valve (34), contains an intermediate container (24) filled, for example, with a grain material (27), arranged in its middle to be traversed from top to bottom by the polluted air (28), which defines with the inner wall of said container (2) an annular space (33) for the filtered air, and which contains at the top and at the bottom a circular perforated sheet (26) disposed horizontally on its entire section, which sheets provide at the top and relative to the lid (31) with central opening of said intermediate container, as well as at the bottom relative to the bottom (29) of the container, empty spaces (30, 32) which , in combination with the annular space provided between the container and the intermediate container, ensure the passage of air, these spaces, as well as those of the fine filter (38) in the shape of a star arranged in the container (2) adjacent, which can in the case of a strong contamination of the accumulated dust, be filled by pouring from the top, a radiation protection medium in the liquid state but capable of self-hardening such as concrete.  4. Element according to any one of claims 1 to 3, characterized in that the container (2) for pre-filtration is equipped with two concentric annular perforated walls (44, 45) arranged on the field one inside the other , covered in their upper part (47) and closed by a cover (31) by determining an intermediate space filled with divided material (27), these walls further defining a porous central tube (45), and with the internal wall of the container (2), an annular space (33), so that the pre-filtered air which, flowing from top to bottom from the supply pipe (37) in the aforementioned porous tube (45), has passed through laterally the layer (27) according to its thickness and its length, goes up towards the cover (36) and passes from there through the closable connection tubing device (25) and the cover (36) of the adjacent container (2) to arrive to the filter for suspended substances (46) incorporated therein for its final purification, passes through this filter re from outside to inside, reaches the central closable tube (39) and from there to the starting pipe (43). 5. Filter element according to any one of the preceding claims, characterized in that the waste container (2) for pre-filtration, filled with material divided into grains (49 and 50), contains a central tube (51) and three perforated walls (48) in the form of a disc which extend over its entire section and which divide its interior space into two cylindrical halves filled with sands of different granulations (50, 49) than the polluted air (28) coming from the supply pipe (52) through the cap (40), crosses in succession from top to bottom, while after passage in space located between the perforated wall (48) lower and the bottom (13) of the container (2) , the pre-purified air stevacuates the latter through the central tube (51) to arrive at the starting pipe (53), arranged above that of the supply pipe (52).  6. Filter element according to any one of the preceding claims, characterized in that the waste container (i) for pre-filtration is equipped with an intermediate container (57) traversed from top to bottom by the polluted air. (28), this container household # ant relative to the side wall of the container an annular void space (56), while its interior space contains three perforated walls (48) in the form of a disc so as to determine two spaces or cylindrical halves filled, for example, with fractions of sand (50, 49) of increasing fineness in the direction of the air flow, leaving between the lower perforated wall (48) and the bottom (13) of the container (2) , as well as between the upper perforated wall (48) and the opening lid <58) of the intermediate container (57), spaces (30, 59), so that the air1 (28) coming from the brought (53) through a central tube (54) with oblique sealing flanges (55), passes vertically through the filt layers rantes (50, 49) arranged one above the other and can be evacuated in the pre-purified state by the annular space (59) provided between the side walls of the container (2) and the intermediate container (57), pass into the interior space of the lid (40) of the container and evacuate through the starting pipe (52). 7. Filter element according to any one of the preceding claims, characterized in that the waste container (2), filled with divided material, for example porous sand, or an activated contact agent (50 and 49) , contains a vertical separating partition (61) passing exactly through its axis and which separates a coarse layer (50) from a thinner layer (49), these layers being retained between inclined upper and lower separating perforated walls (62) in the form of a roof, while the polluted air first crosses from top to bottom the layer (50) with coarse granulation, then from bottom to top that (49) finer granulation, the hat cover (40) locked from removably to the container (2) containing for this purpose inlet (60) and outlet (64) pipes with shut-off valves (8) which open respectively into the inlet (37) and outlet (43) pipes ) arranged next to each other.  8. Filter element according to any one of the preceding claims, characterized in that the waste container (2) for pre-filtration is divided by at least three cylindrical perforated walls (65, 66, 67) somewhat closed in the high and arranged concentrically one inside the other, so as to determine two annular spaces located one after the other in the direction of the flow and which are filled with divided matters (50, 49) of granules different, polluted air (28), which comes from the upper supply pipe (53) via a central tube (54) disposed through the cap (36) of the container (2), arriving in the latter, then flowing horizontally in contact with the filter layers (50 and 49) to escape through the annular space (68) formed between the outer perforated wall (65) and the side wall of the container, reaching the cover (36) and from there to the purified air outlet pipe (52) located above c this one.  9. Filter element according to any one of the preceding claims, characterized in that to seal between the flange (5) of the cover and that of the waste container (2) pre-filtration, it comprises a mechanism to levers (70, 71, 72) associated with clamping hooks (73) driven by elastic washers (74), this mechanism comprising two shafts (77) carried in rotation by two crosspieces (76) integral with the cover, these shafts carrying levers with two arms (72) to each of which a hook (73) is articulated, while at the other arm of each lever is coupled to the front of the mechanism a rod or rod for transmitting force (71), respectively right and left, the other end of which is articulated to a device (70) of scissors with four rods, on which acts for example a pneumatic or hydraulic cylinder (69) which brings the rods to their neutral position unstable balance so that this cylinder can remain at rest per during the operation of the filter. 10. Filter element according to any one of the preceding claims, characterized in that between the cover (5) and the flange of the waste container (2) is arranged an elastic clamping mechanism by levers comprising two rods or connecting rods ( 79) actuated by a vertical threaded rod (78) carried. rotating by two bearings (80), this rod being driven by a ratchet lever system (81) or a motor (82) through an eccentric and a lever, so as to move a sleeve up or down threaded (83) mounted on it and to which the connecting rods (79) are articulated, which in turn are coupled to the four levers (72), to the shafts (77) and to the elastic hooks (74), so that when the connecting rods (79) arrive horizontally, the entire mechanism is in neutral position of unstable equilibrium which ensures self-locking and makes it possible to relieve the control member from any effort (82). 11. Filter element according to any one of the preceding claims, characterized in that it comprises a sleeve (84) With internal right and left threads, driven in the manner of a winch by means of a central snap ( 86) using a lever or a cylinder (69) operating in pulses, this sleeve acting on two rods. threaded (87) which it pushes towards the double levers (72) to which they are articulated, so as to actuate the elastic clamping hooks. (73) to apply the container (2) against the cover or if necessary remove it.  12. Filter element according to any one of the preceding claims, characterized in that the entire container (2) is lifted and applied against the cover by a plate actuated by a scissor device, this plate being either fixed in permanent place (plate 88), or carried by a wheeled cart (plate 95) so as to be mobile, which plate is actuated by a central rotating screw (89) of known type and by levers (91) articulated on threaded sleeves (96) mounted on it, the threaded rod being itself optionally driven by a ratchet (90) or by an appropriate automatic member, while in the case of the plate (95) mounted on wheels, these (93 ) are centered by depressions (94) provided in the ground. 13. Filter element according to any one of the preceding claims, characterized in that a mobile installation comprises two waste containers (2), a fan (99) and a suction sleeve (97), the pre-filter (3) provided in the first container (2) containing coarse grinding sand disposed in one or two successive layers, or fine basalt or lava sand, while the filter, contained in the second container (2) is constituted by another suitable contact or separation medium for post-filtration or, respectively, that this second container (2) is provided with a large-area filter for suspended substances, made for example of pleated paper (4, 28 , 46) presented in the form of discs, cartridges, stars, or blocks.