FR2564746A1 - Avoiding corrosion of energy transfer system - Google Patents

Abstract

In removing polluting sulphur cpds. from hot combustion fumes by a reactive spray washer, their initial high temp. is reduced to about 50 deg.C. To take the cleaned fumes to the min. 72 deg.C temp. needed for adequate chimney discharge they are heated in the zone by an exchanger operating with fluid circulated from an exchanger in the hot inlet zone, through connecting pipes and a pump. Similar interchange of fluid takes place between exchangers in the zones more immediately proceding and following the washer. Heat exchangers in the hotter zones where temp. does not drop to the dew point for H2SO4 are made of thick-walled finned steel tube, the connecting pipes are also steel. The lower temp. exchangers and connecting pipes are made of or coated with corrosion-resistant and anti-adhesive plastic, esp. PTFE, PV fluoride or polypropylene.

Description

ENERGY TRANSFER DEVICE,
EQUIPPED WITH A DESULFURIZATION INSTALLATION
The present invention relates to an energy transfer device fitted to a desulfurization installation, in which a heat exchanger is incorporated in the flow of raw gases before the washer, this exchanger being connected by means of a heat transfer agent. having in the form of a fluid in forced circulation, for a fluid exchange, to another heat exchanger incorporated in the flow of purified gases behind said washer, the transfer conduits, as well as said heat exchangers possibly having tubes with heat exchange fins, consisting of a material resistant to pressure, such as for example steel.

 Increased efforts to protect the environment have led to the fact that, both when new thermal power plants are installed and in existing thermal power plants, preventive measures must be taken to desulphurize the flue gases . First of all, wet desulphurization systems are used. In these systems, during the purification process, the flue gases are cooled by a washing solution so that they leave the washer at a temperature of around 500 C.

 However, it is however necessary that the purified flue gases are again heated to at least 720 ° C. before they can enter the atmosphere. Different methods have been developed to cause this heating. Among the most favorable methods from the point of view of energy savings, are those in which the heat energy necessary for heating is taken from the hot raw gases not yet purified.

 To this end, a heat exchanger with heat exchange tubes fitted with fins has been incorporated into the flow of raw gases, upstream of the washer, and this heat exchanger has been connected via a heat transfer agent in the form of a fluid (commuted for example water protected against freezing), to another heat exchanger which contains finned heat exchange tubes, and has been disposed downstream of said washer in the flow of purified gases. Consequently, using this device, heat could be removed from the flow of raw gases and be transferred to the purified gases, via the heat transfer fluid. In this case, the heat exchangers, tubes and pipes for transferring the heat transfer fluid generally consist of steel, but this involves considerable difficulties in the presence of temperatures close to the dew point of sulfuric acid. This is why it has already been proposed to coat the individual parts of a heat exchanger. However, it then turned out that, as a result of the macromolecular structure of the coating materials, in the long term, under the coating, residues of diffuse molecules formed, resulting in both destruction of the base material and peeling of the coating. Enamelled heat exchangers have also already been used in conjunction with flue gas desulphurization plants. For the most diverse reasons, all the aforementioned measures have so far been unsatisfactory for specialists.

 The object of the invention is to improve the energy transfer device described above, equipping a desulphurization installation, so that flawless purification of the flue gases can be obtained with a long period of use, and without the use of expensive materials.

 According to the invention, this object is achieved by the fact that, in the flow of. raw gases between a heat exchanger and the washer, as well as in the purified gas flow between said washer and another heat exchanger, are incorporated respective heat exchangers which operate at a lower temperature level, are provided with flexible pipes or tubes made of a corrosion-resistant non-stick plastic material, and are connected to each other, allowing the circulation of the heat-transfer fluid, by means of transfer conduits consisting of a plastic material which, too, is at least resistant to corrosion, all the parts of the low temperature heat exchangers with which the gases are in contact being sheathed or coated with a non-stick plastic material resistant to corrosion.

 In this case therefore, two heat transfer systems operating at different temperature levels are arranged in succession. The raw gases which are still very hot, at a temperature of around 140 ° C., first pass through a heat exchanger fitted with thick-walled steel tubes, smooth or provided with fins. There is then a cooling down to approximately 1150 C. The heat transfer agent takes the heat from the raw gases and transmits it to the purified gases, by means of the heat exchanger incorporated in the flow of the purified gases. circulation of the heat transfer fluid, it is ensured that the prevailing temperatures are constant and situated in a range from 1050 ° C. to 1200 ° C., so that no place in the heat transfer system consisting of steel can accuse temperature migrations below the dew point of sulfuric acid.

Indeed, in the presence of temperatures above 650 C, the drops of liquid, still contained by the purified gases behind the drop separator of the washer, are almost all evaporated.

Consequently, there can no longer be any crusting on the surfaces of the heat exchanger located in the purified gases.

Naturally, for safety reasons, an additional installation of soot blowers can be carried out.

 In the second stage, that is to say at a lower temperature level, there is now used a heat transfer system constituted by non-stick plastic materials and resistant to corrosion. The temperatures of the heat transfer fluid provided for this purpose have the consequence that the raw gases are cooled, for example, from 115 C to 950 C. The heat transfer fluid circulating in this plastic heat transfer system shows temperatures of the order of 75 "C. Thus, because of this temperature level, the dew point of sulfuric acid is crossed, on the raw gas side, in the vicinity of the heat exchanger incorporated there. The acid thus produced s "partially drips or drips down on flexible pipes or tubes, or, respectively, this acid to which ash is added adheres to said pipes or tubes. To ensure cleaning, it is possible to use water which can be collected and delivered to the washer.

 The heat, taken from flexible pipes or plastic tubes using the circulating heat transfer fluid (which may consist of water protected from freezing), is directed to the low temperature heat exchanger interposed between the washer and the steel heat exchanger, in the stream of purified gases, to then be transmitted to said purified gases, via this heat exchanger. In this case, the purified grz heat up by about 500 C up to temperatures exceeding 650 C. In this way we obtain an evaporation of all the drops of water which are still enclosed by the gas flow on the side intake of the heat exchanger. It can then happen that the gypsum enclosed by the said drops is deposited, thereby causing gypsum crusts to form on the surface of the plastic. However, due to the non-stick surface properties of the plastic used, these crusts can be easily removed by vibration. A temperature variation can also be used to ensure this cleaning.

The invention therefore makes it possible to use as a material, in the high temperature range beyond the dew point of sulfuric acid in the flow of raw gases and above 650 C in the dry region of the flow of purified gases, a conventional pressure-resistant material, for example steel. However, in the lower temperature range, both in the flow of raw gases and. in the purified gas flow, flexible plastic tubes or pipes are used respectively which are practically under no pressure
The implantation of the two heat transfer systems, arranged in staggered succession, can take place anywhere in the respective streams of raw gases and purified gases. Even distances exceeding 50 m between the heat exchangers arranged in the respective flow of raw gases or purified gases in the system considered, and and communicating with each other by means of a heat transfer fluid, do not constitute any obstacle. In addition, the invention makes it possible to easily retrofit old installations. Because the purified gases cannot be soiled by the raw gases, it is possible to install a blower both in the dry raw gas flow and in the flow of dry purified gases. The degrees of separation achieved in the scrubber remain the same, that is, they also constitute the separation rates of the flue gas desulphurization plant. Given the possibility of using known durable and corrosion-resistant materials, a long service life is obtained which, even with a long operating life, does not cause any wear on the heat exchangers.

 According to an advantageous embodiment, the low temperature heat exchangers and their transfer conduits can consist of polytetrafluoroethylene, polyvinylidene fluoride or polypropylene, or else be sheathed or coated with polytetrafluoroethylene, polyvinylidene fluoride or polypropylene respectively. . Heat exchangers made of such plastics can, of course, be designed only for relatively low internal pressures. In the presence of higher temperatures and higher pressures, the aforementioned materials tend to creep, so that both the temperature and the internal pressure must be guaranteed. However, it is then possible to take full account of the relatively low pressure resistance of plastics, by choosing the temperature of the heat transfer fluid below 1000 C, as well as by causing the water to fall in cascades in front of the individual heat exchangers. It is thus guaranteed that the pressures developing in the heat exchangers never exceed the admissible value. Likewise, sudden increases in temperature in the flue gases cannot increase the pressure exerted on the internal face.

 According to the invention, the transfer conduits between the low temperature heat exchangers can be connected to each other by a bypass. Thus, the temperatures of the heat transfer fluid are always maintained for sure at the desired level. This advantageous characteristic naturally also applies to the heat transfer system made of steel in the first stage.

 In the presence of heat exchangers conveniently arranged at different geodesic heights and traversed by water as a heat transfer fluid, to prevent the pressure from increasing disproportionately, low temperature heat exchangers are at different geodesic heights and it can be provided, respectively before or after said low temperature exchangers, a respective intermediate accumulator of the heat transfer agent. It is thus ensured that only a predetermined water pressure can be delivered to the heat exchanger 11 considered.

The water, which transmits heat from the raw gases to the purified gases, circulates through the heat exchangers - as a result of the slope. Return circulation is ensured by means of a pump.

 To allow monitoring of the evacuation of the heat transfer fluid through the heat exchanger occupying a lower geodesic position, a pressure-controlled control valve can be incorporated in the transfer duct extending from the low temperature heat exchanger occupying a higher position at the low temperature heat exchanger occupying a lower position.

 According to a particularly advantageous embodiment of the invention, when the device is traversed by a horizontal gas flow, the low temperature heat exchangers can be provided with flexible pipes or plastic tubes which are U-shaped and are suspended from up and down, both in the raw gas flow and in the purified gas flow. Such pipes or tubes can be combined into bundles, so that individual heat exchange bundles can also be deposited individually by sliding and be replaced during operation. Thanks to the U-shaped configuration of the flexible pipes or tubes, the distributor and manifold chambers can be relegated to the outside of the gas flow, which guarantees accessibility in a simple manner.

 When the gas flow is vertical, it can also be provided, instead of flexible pipes or plastic tubes in a U-shape, flexible pipes or plastic tubes hanging freely in the horizontal direction.

 The fixing of flexible pipes or plastic tubes in the bottoms of the heat exchangers is ensured by the fact that the free ends of these pipes or tubes can be stopped in said bottoms of the exchangers, by means of interlocking sockets which can be widened. To this end, the pipes or tubes are first inserted in the tubular bottoms. Then the push-in sockets are inserted into the end sections, then widened. In this context, it is advantageous that the plug-in sockets consist of copper or brass.

 When, in accordance with the invention, the external end sections of the plug-in sockets are flared in the form of a funnel, there is each time formed, at the end of the flexible pipe, a water inlet fitting suitable for flow and resulting in low losses.

 According to the invention, the length of the nestable sockets can be dimensioned greater than the thickness of the bottoms of the heat exchangers. This eliminates any possibility of bending the flexible pipes or tubes on the tubular bottom.

 According to the invention, the distributing chambers and the collecting chambers of the low temperature heat exchangers can be separated from the gas streams by gas-tight and corrosion-resistant surfaces. In this way, it is possible to control during penetration of the individual pipes or tubes in the distributing or collecting chambers, as well as to pinch said pipes or tubes in an emergency. This measure also authorizes the use of classic materials 3 great robustness for producing distribution and collector chambers and, independently of this, the use of materials protected against corrosion, but less resistant and intended to be engaged in the gas-tight surface.

 The self-hernetic subjection of flexible pipes or plastic tubes in gas-tight surfaces is obtained by the elasticity of said pipes or tubes, combined with the water pressure which is exerted during operation on the face internal flexible hoses, and is higher than expected gas pressures.

 The fact that, in accordance with the invention, cleaning water is delivered in jerks ensures easy purification, in combination with the non-stick surface property of plastics. In this case, soot, dust and sulfuric acid are removed by washing. In this regard, a distributor tube can be engaged in each bundle, a tube from which cleaning water exits laterally at predetermined intervals.

 According to the invention, the flexible pipes or tubes of plastic material can be guided between the gas-tight surfaces and the curved longitudinal sections, by means of at least one spacer plate laterally sloping downwards, like a roof, from the vertical longitudinal median plane. Such a plate or several plates of this kind not only ensure flawless guidance of flexible pipes or plastic tubes, but they also guarantee an adequate drainage of the cleaning water.

 The fact that at least the low temperature heat exchanger located in the stream of purified gases can be subjected to vibrations offers the possibility of eliminating by vibration the adhering dirt. These vibrations can also be combined with thermal expansions of the plastic, whereby adherent particles are expelled during temperature variations.

For this purpose, it suffices to ensure that the expansion of the flexible pipes and tubes is not hampered in the longitudinal direction.

The invention will now be described in more detail by way of non-limiting examples, with reference to the appended drawings in which
Figure 1 is a schematic representation of a flue gas desulphurization installation, provided with two heat transfer systems in staggered succession in the flue gas flow;
Figure 2 is a schematic plan view of a heat exchanger for the heat transfer systems of Figure 1;
Figure 3 shows an enlarged representation of a detail of one heat exchanger of Figure 2
Figure 4 is a fragmentary section, on a larger scale, of detail IV of Figure 3;
Figure 5 illustrates, in a perspective view with cutaway, other details of the heat exchanger of Figure 2; and
FIG. 6 schematically represents another embodiment of a heat transfer system.

 The installation 1 illustrated diagrammatically in FIG. 1 is for example part of a coal-fired thermal power plant, and is used for the desulfurization of the flue gases produced by this power plant.

 A ROS flow of raw gases, leaving an electrostatic precipitator 2 in the direction of the arrow, has a temperature of approximately 140 C and, at this temperature, it first passes through a heat exchanger 3 which consists of l steel and has a series of heat exchange tubes extending parallel to each other and provided with fins, these tubes however not being illustrated in detail in the drawing.

 At its exit from the heat exchanger 3, the ROS flow of raw gases still shows a temperature of approximately 1150 C. At this temperature, said ROS flow requests another heat exchanger 4 which will be the subject of a detailed commentary in support of Figures 2 to 6.

 The ROS flow of raw gases leaves this heat exchanger 4 at a temperature of approximately 950 C and it enters a washer 5, in which it is freed of its sulfur under the action of humidity.

When they come out of washer 5, the now purified flue gases have a temperature of around 480 C, with which a flow
RES of the purified gases passes through a heat exchanger 6 in communication, by heat exchange, with the exchanger 4 located in the flow
ROS of raw gases. In this exchanger 6, the flow RES of the purified gases is heated to around 680 C, after which it passes through another heat exchanger 7 communicating, by heat exchange, with the exchanger 3 incorporated in the flow ROS of raw gases.

 On leaving the heat exchanger 7, the flow RES of the purified gases has a temperature of around 900 ° C., with which it is transmitted to the atmosphere via a chimney 8.

 The heat exchangers 3 and 7, incorporated in the respective flows ROS of the raw gases and RES of the purified gases and provided with thick-walled and finned steel tubes, are in fluid communication by means of transfer conduits 9 and 10. The fluid consists of water protected from freezing. This water is heated to approximately 1200 C in the exchanger 3 and it then travels through the conduit 9 to reach the exchanger 7 located in the flow RES of the purified gases, exchanger in which it is cooled to approximately 1050 C.

The return of the heat transfer fluid is ensured by a pump 11 housed in the conduit 10. A regulation device provided with a bypass 12 makes it possible to maintain the temperatures of the heat transfer fluid between 1050 ° C. and 1200 ° C., so that no place in the system 13 of thermal transfer consisting of steel does not show temperature migrations below the dew point of sulfuric acid.

 The heat exchangers 4 and 6, forming part of the second stage 14 of the desulfurization installation 1 and incorporated on the one hand into the ROS flow of raw gases and on the other hand into the RES flow of purified gases, are also connected. to each other via transfer conduits 15 and 16. In this thermal transfer system 14, water also protected from freezing circulates in a temperature range between 700 C and 80 C. In the exchanger 4 located in the ROS flow of raw gases, this water is heated to around 800 C and, from this exchanger, it borrows the conduit 15 to reach the exchanger 6 located in the flow RES, in which it transfers heat to purified gases. From the outlet, this heat transfer fluid cools down to around 700 CA at this temperature, the heat transfer fluid returns to the heat exchanger 4 in the ROS flow, for example using a pump 17. The conduits 15 and 16 are interconnected by a branch 18.

 Since the temperatures of the heat transfer agent circulating in the second transfer system 14 are of the order of 750 ° C., the dew point of sulfuric acid is crossed on the side of the raw gases. In this case, to avoid deterioration of said system 14, all the parts of the two heat exchangers 4 and 6 with which the gases come into contact are sheathed or coated with a non-stick plastic material and resistant to corrosion.

This plastic material can be polytetrafluoroethylene, polyvinylidene fluoride or polypropylene. The transfer conduits 15 and 16 between the two exchangers 4 and 6 may also consist of a plastic material at least resistant to corrosion.

 With a view to heat exchange (see Figures 2 and 3), when the gas flow is horizontal, flexible plastic pipes configured in U shape are suspended from top to bottom, being grouped in bundles, both in the ROS flow of raw gases than in the RES flow of purified gases. These flexible pipes consist of a plastic material of the polytetrafluoroethylene, polyvinylidene fluoride or polypropylene type.

 FIG. 2 shows for example that the heat exchanger 4 incorporated in the ROS flow of raw gases, as well as the heat exchanger 6 located in the RES flow of purified gases, are both subdivided into three zones A, B and C, the maintenance of which can be carried out each time individually, even during operation.

The grouping of flexible plastic pipes 19 in a U, in each zone A, B or C (FIG. 3), offers the advantage that only a distribution chamber 20 and a collection chamber 21 can be arranged at a relegated level outside the respective gas flow ROS or RES. The separation takes place through a gas-tight surface 22, consisting of suitable materials. The heat transfer agent enters the distribution chambers 20 (and consequently the pipes 19) according to arrow 23, and leaves each zone A, B or C according to arrow 24.

 As shown in FIG. 4, the fixing of the individual pipes 19 in the bottoms 25 of the distributing chambers 20 and of the collecting chambers 21 is ensured by the fact that these pipes 19 are introduced into corresponding bores 26 platicated in the bottoms 25, to then be locked by nestable sockets 27 made of copper or brass, pressed in and enlarged. The shape of the sockets 27 is chosen in such a way that an infundibuliform connection 28 of water inlet or outlet, respectively, is created, which causes low losses due to the flow. lement. In addition, the length L of the plug-in sockets 27 is chosen to be greater than the thickness D of the tubular bottoms 25. This prevents the possibility of bending of the pipes 19 on the bottoms 25.

 The flexible pipes 19 are secured in the gas-tight surface 22 (FIGS. 3 and 4) by the pressure of the water which is exerted in service on the internal face of said pipes 19 and which, as a result of gas pressures more modest, which should be expected, guarantees an airtight crossing.

The reference 29 designates a spacing element which keeps the distributing chambers 20 and collecting chambers 21 at the necessary distance from the gas-tight surface 22.

As shown in Figures 2 and 5, each area A,
B, C of the heat exchangers 4 and 6 is crossed by a vertical tube 30. The tubes 30 are hermetically mounted in the surfaces 22 and have lateral outlet orifices 31 at different heights. Consequently, a supply of cleaning water according to the arrows 32 makes it possible, if necessary, to jerky clean the flexible pipes 19 grouped in bundles in each zone A,
B, C (Figure 3). The cleaning water can then come from the evacuation fittings 34, via tanks 33. All the parts of the respective heat exchanger 4 or 6 which come into contact with the flue gases consist of a plastic material. resistant at least to corrosion. These parts are guides 35 of the bundles, jackets 36, the tanks 33 and the evacuation fittings 34.

 In addition, a joint observation of Figures 5 and 3 reveals that the individual flexible pipes 19 undergo forced guidance at different heights. Spacing plates 37, laterally sloping downwards in the manner of a roof, from the vertical longitudinal median plane, are provided for this purpose. The inclination in the form of a roof allows the cleaning water to flow impeccably towards the outside, in the tanks 33. If necessary, the whole of the heat exchanger 4, 6 or individual parts of this exchanger may be subjected to vibrations. The vibratory system necessary for this purpose is not illustrated in detail in the drawing.

 FIG. 6 represents an embodiment in which the low temperature heat exchangers 4 and 6 of the second heat transfer system 14 are arranged at different geodesic heights. To prevent the pressure from increasing disproportionately in these exchangers 4 and 6, respective intermediate accumulators 38 and 39, respectively provided in front of and behind said exchangers 4 and 6, ensure that a predetermined water pressure can be delivered to each exchanger considered 4 , 6. The water, transmitting heat from the ROS flow of raw gases to the RES flow of purified gases, flows through exchangers 4 and 6 as a result of the slope. The evacuation through the heat exchanger 6 occupying a lower geodesic position is monitored by a regulating valve 40 housed in the duct 15 and controlled by the pressure. Via the pipe 16, a pump 17 delivers the heat transfer fluid from the water accumulator 39 to the water accumulator 38.

 It goes without saying that many modifications can be made to the device described and shown, without departing from the scope of the invention.

Claims (16)

 1. Energy transfer device, fitted to a desulphurization installation and in which a heat exchanger is incorporated in the flow of raw gases before the washer, this exchanger being connected by means of a heat transfer agent in the form of a fluid in forced circulation, for a fluid exchange, to another heat exchanger incorporated in the flow of purified gases behind said washer, the transfer conduits, as well as said heat exchangers possibly having exchange tubes thermal provided with fins, consisting of a material resistant to pressure, such as steel, device characterized in that, in the flow (ROS) of raw gases between the heat exchanger (3) and the washer (5), as well as in the flow (RES) of the purified gases between said. washer (5) and heat exchanger (7), are incorporated respective heat exchangers (4, 6) which operate at a lower temperature level, are provided with flexible pipes or tubes (19) made of an anti plastic -adherent corrosion resistant, and are connected to each other, with circulation of the heat transfer agent, by means of transfer conduits (15, 16) consisting of a plastic material which, too, is at least corrosion resistant , all the parts (33 - 37) of the low temperature heat exchangers (4, 6) with which the gases are in contact being sheathed or coated with a non-stick plastic material resistant to corrosion.  2. Device according to claim 1, characterized in that the low temperature heat exchangers (4, 6) and their transfer conduits (15, 16) consist of polytetrafluoroethylene, polyvinylidene fluoride or polypropylene, or many are respectively sheathed or coated with polytetrafluoroethylene, polyvinylidene fluoride or polypropylene.  3. Device according to one of claims 1 and 2, characterized in that the transfer conduits (15, 16) between the low temperature heat exchangers (4, 6) are connected to each other by a bypass (18).  4. Device according to any one of claims 1 to 3, characterized in that the low temperature heat exchangers (4, 6) are arranged at different geodesic heights and a respective intermediate accumulator (38, 39) of the heat transfer fluid is respectively provided in front of or behind said low temperature heat exchangers (4, 6).  5. Device according to claim 4, characterized in that a pressure control regulating valve (40) is incorporated in the transfer duct (15) going from the low temperature heat exchanger (4) occupying a position high to 1 low temperature heat exchanger (6) occupying a lower position.  6. Device according to any one of claims 1 to 5, with a horizontal gas flow, device characterized in that the low temperature heat exchangers (4, 6) are provided with flexible pipes or tubes (19) made of plastic, which are U-shaped and suspended from top to bottom both in the flow (ROS) of raw gases and in the flow (RES) of purified gases.  7. Device according to any one of claims 1 to 5, with vertical gas flow, device characterized in that flexible pipes or tubes (19) made of plastic, freely hanging in the horizontal direction, are provided in the heat exchangers low temperature (4, 6).  8. Device according to any one of claims 1 to 7, characterized in that the free ends of the flexible pipes or tubes (19) of plastic material can be stopped, in the bottoms (25) of the heat exchangers, by sockets nestable (27) can be widened.  9. Device according to claim 8, characterized in that the nestable sockets (27) consist of copper or brass.  10. Device according to one of claims 8 and 9, characterized in that the external end sections (28) of em bootable sockets (27) are flared in the form of a funnel.  11. Device according to any one of claims 8 to 10, characterized in that the length (L) of the plug-in sockets (27) is dimensioned greater than the thickness (D) of the bottoms (25) of the heat exchangers.  12. Device according to any one of claims 1 to 11, characterized in that the distributing chambers (20) and the collecting chambers (21) of the low temperature heat exchangers (4, 6) are separated from the gas flows (ROS , RES) by gas-tight and corrosion-resistant surfaces (22).  13. Device according to claim 12, characterized in that the flexible pipes or tubes (19) of plastic are subject with self-sealing effect in the surfaces (22) gas tight.  14. Device according to any one of claims 1 to 13, characterized in that the cleaning water is delivered by jerks to the flexible pipes or tubes (19) made of plastic.  15. Device according to one of claims 13 and 14, characterized in that the flexible pipes or tubes (19) of plastic material are guided, between the surfaces (22) gas tight and the curved longitudinal sections, by the intermediate at least one spacer plate (37) laterally sloping downwards, like a roof, from the vertical longitudinal median plane.  16. Device according to any one of claims 1 to 15, characterized in that at least the low temperature heat exchanger (6) located in the flow (RES) of the purified gases can be subjected to vibrations.