WO2003074158A1

WO2003074158A1 - Installation and filtering device for recovering volatile organic compounds and method for regenerating the filtering device

Info

Publication number: WO2003074158A1
Application number: PCT/FR2003/000654
Authority: WO
Inventors: Mario Dallot
Original assignee: Amsonic Branson Sas
Priority date: 2002-03-01
Filing date: 2003-02-28
Publication date: 2003-09-12
Also published as: AU2003222951A1; FR2836637A1

Abstract

The invention concerns a filtering device for recovering volatile organic compounds, in particular of the type comprising a filtering body (2) provided with means for connection (11) to a circuit of effluents to be treated and which contains regenerable adsorption agents (8). The invention is characterized in the filtering body (2) defines at least a heating chamber (3) sealingly traversed by at least a filtering tube (4) containing the regenerable adsorption agents.

Description

INSTALLATION AND FILTRATION DEVICE FOR RECOVERY

OF VOLATILE ORGANIC COMPOUNDS

AND METHOD FOR REGENERATING THE FILTRATION DEVICE

The present invention relates to the technical field of treatment and filtration of gaseous effluents before their release into the atmosphere.

The object of the invention relates, more particularly but not exclusively, to the recovery of volatile organic components, for example, solvents in the general sense, such as halogens or chlorines emitted, for example, at the outlet of a degreasing machine .

In the above field, it is known to use filtration devices containing a charge of agents for adsorbing volatile organic compounds (VOCs), such as, for example, activated carbon particles.

Such devices have the advantage of ensuring a particularly efficient capture of VOCs, while offering a possibility of regeneration when the activated carbon particles are saturated with VOCs.

This regeneration is most often carried out by injecting, into the bed of activated carbon particles, a hot gas, such as, for example, heated air and / or air charged with water vapor which takes VOCs with it.

Such a regeneration process effectively makes it possible to restore the adsorption capacities of the activated carbon particles but has, however, the drawback of requiring relatively large installations for the supply of hot gases or steam. In addition, it is necessary to pass, within the charge of activated carbon, a relatively large volume of hot gases, in order to obtain a sufficient rise in temperature. However, the volume of hot gases will then have to be treated in order to recover the VOCs extracted from the regenerated filtration device. Given the large volume of regeneration gas to be treated, the installation for recovering VOCs, used in the regeneration phase, should also be relatively large. Thus, the regeneration means to be used substantially increase the size and the price of the filtration installation.

It therefore appears the need to be able to have a filtration device which can be easily regenerated, without the implementation of a large and expensive regeneration installation, while retaining a good yield of recovery of VOCs. In order to achieve this objective, the invention relates to a filtration device for the recovery of volatile organic components, in particular of the type comprising a filtration body which is equipped with means for connection to an effluent circuit to be treated and which contains regenerable adsorption agents. According to the invention, the filtration device is characterized in that the filtration body defines at least one reheating chamber, crossed in leaktight manner by at least one filtration tube containing regenerable adsorption agents.

The implementation of an independent reheating chamber makes it possible, very advantageously, to dissociate, during the regeneration of the device, the heating functions of the adsorption agents and of transport of the volatile organic compounds released by these agents. adsorption. Thus, the heating of the regenerable adsorption agents can be carried out independently of the recovery of the volatile organic compounds released by the adsorption agents in the regeneration or desorption phase.

According to a preferred embodiment, in order to increase the rate of reheating of the adsorption agents, as well as to ensure good homogeneity of the temperature within the mass of adsorption agents, the filtration body comprises a bundle of filtration tubes which pass tightly through the reheating chamber and which open, at each of their ends, into a collecting chamber. Thus, the implementation of a bundle of tubes makes it possible to divide the mass of adsorption agents into small quantities of small thickness and therefore easier to reheat. According to the invention, the heating chamber can be brought to temperature in any suitable manner. Thus, the heating of the reheating chamber can be carried out by means external to the filtration device, such as, for example, by means of a heat-transfer fluid, and the reheating chamber then comprises means for connection to a circuit of supply of hot heat transfer fluid, such as, for example, superheated water or steam. According to the invention, the means for heating the reheating chamber can also be integrated into the filtration device.

Thus, the reheating means can, for example, be constituted by electrical resistors, arranged inside the reheating chamber while being wound, for example but not exclusively, around the filtration tubes. Thus, the transfer of heat between the electrical resistances and the particles of adsorption agents to be regenerated takes place directly by conduction. According to another embodiment, the heating chamber contains a heat transfer fluid and the filtration device is equipped with means for heating the heat transfer fluid, such as, for example but not exclusively, electrical resistances. This advantageous arrangement of the invention then ensures the establishment, within the heating chamber, of a uniform temperature by convection of the heat transfer fluid.

Preferably, the heat transfer fluid consists of a vaporizable liquid, such as, for example, water, which will be vaporized during the regeneration or desorption phase of the adsorption agents.

Preferably, in order to promote convection phenomena, the heating means are placed in the lower part of the heating chamber.

According to the invention, the adsorption agents can be of any suitable nature, depending on the type of volatile organic compounds to be captured and insofar as, of course, the adsorption agents remain regenerable.

Thus, the adsorption agents can be made up or comprise particles or fibers of activated carbon. Similarly, the adsorption agents can be made up or comprise fibers or particles of adsorbent resins or other adsorbent material chosen as a function of the VOCs to be treated.

The invention also relates to a filtration installation for the recovery of volatile organic components comprising a main pipe for circulating effluents to be treated and means for recovering volatile organic components. According to the invention, the recovery means comprise at least one filtration device according to the invention which is connected to the effluent circulation pipe to be treated.

According to a characteristic of the invention, the installation comprises a desorption circuit connected to the so-called main filtration device and equipped with means for recovering the VOCs released by the main filtration device during a desorption phase. Such recovery means can, for example, consist of at least one filter, called a secondary filter, comprising VOC adsorption agents and / or at least one condenser ensuring the recovery of the condensable VOCs.

Furthermore, since, according to the invention, the filtration circuit of the filtration device is independent and separated in a sealed manner from the means for reheating the adsorption agents, it is possible, during the desorption phase, to '' establish a relative vacuum within the filtration circuit, in order to favor the release of volatile organic compounds by adsorption agents. Thus, according to another characteristic of the invention, the desorption circuit comprises a vacuum pump. The invention also relates to a process for regenerating a filtration device with regenerable VOC adsorption agents, characterized in that it consists in heating, by thermal conduction, the VOC adsorption agents and in establish a relative vacuum within the filtration device.

Various other characteristics of the invention will emerge from the description below, given with reference to the drawings which illustrate nonlimiting examples of the production of a filtration device according to the invention and of an installation for implementing it. of the last.

Fig. 1 is a schematic longitudinal section of a preferred embodiment of a filtration device according to the invention.

Fig. 2 is a block diagram of a preferred embodiment of an installation implementing a filtration device according to the invention.

Fig. 3 is a schematic longitudinal section of another embodiment of a filtration device according to the invention.

A filtration device according to the invention, as illustrated in FIG. 1 and designated as a whole by the reference 1, comprises a filtration body 2 which delimits at least one and, according to the example illustrated, exactly a reheating chamber 3 which is crossed, in leaktight manner, by a bundle of tubes of filtration 4. According to the example illustrated, the filtration body 2 has a substantially cylindrical shape and the heating chamber 3 is then delimited by two transverse partitions 5 between which extend the filtration tubes 4. The partitions 5 are perforated at the ends 6 of the filtration tubes 4 which thus open, at each of their ends, in a collecting chamber 7 delimited by the corresponding partition 5 and the filtration body 2. It should be noted that the collecting chambers 7 and the reheating chamber 3 are sealed from one another. Likewise, the filtration circuit, defined by the collecting chambers 7 and the filtration tubes 4, is sealed relative to the heating chamber 3.

In order to allow the incorporation of the filtration device 1 in a gaseous effluent treatment installation, as illustrated in FIG. 2, the filtration device 1 comprises connection means 10 made up, according to the example illustrated in fig.1, by two connection flanges 11 adapted at each of the collecting chambers 7.

In accordance with an essential characteristic of the invention, the filtration tubes 4 contain and, according to the example illustrated, are completely filled with VOC adsorption agents, such as, for example, activated carbon particles. In order to avoid excessive pressure drops while defining transverse thicknesses of particles of adsorbing agents which are easy to heat, the filtration tubes are preferably but not exclusively chosen so as to have an internal diameter between 50 and 100 mm. In the same direction, the activated carbon particles are chosen so as to have a form of rods having a diameter between 3 and 5 mm and a length between 8 and 15 mm.

Of course, it could be envisaged to use another type of adsorption agents, such as, for example, adsorbent resins. In the same sense, it could be envisaged to use, as adsorbent agents, a mixture of particles or fibers of activated carbon and particles or fibers of adsorbent resin. According to the invention, the adsorbent agents used have the particularity of being regenerable or desorbable by heating. Thus, according to the preferred embodiment as illustrated, the filtration device 1 comprises means 15 for heating the reheating chamber 3. The means 15 are preferably but not strictly necessary, constituted by a resistance or a set of electrical resistors 16 placed in relation to the heating chamber 3. According to the example illustrated, the resistors 16 are placed in the lower part of the chamber 3 outside the filtration body 2. In order to be able to ensure a uniform temperature within the reheating chamber 3, the heating means 15 further comprise an amount of a vaporizable liquid 17, such as, for example but not exclusively, water. Thus, as will appear later, the use of resistors 16 makes it possible to obtain a vaporization of the quantity of liquid 17 which establishes, by convection, a substantially uniform temperature within the reheating chamber 3, the heat thus produced then being transmitted by conduction to the adsorption agents 8 confined in the filtration tubes 4.

The device thus formed is implemented in the following manner in an installation according to the invention, as shown diagrammatically in FIG. 2.

As can be seen more precisely in FIG. 2, the recovery installation comprises a main recuperator 1, constituted in the form of a filtration device according to the invention, connected, at the inlet, by a pipe 20 to a source VOC emission 21. The volume of the filtration device is then chosen as a function of the quantity of volatile organic components to be recovered.

In a conventional manner, the recovery device 1 is connected to an air outlet 22 equipped with a system 23 for controlling emissions. During the normal operation of the installation, the gaseous effluents loaded with VOCs from the source 21 pass through the recovery device 1 at the level from which the VOCs are adsorbed by the agents 8, to then be released into the atmosphere at the outlet pipe 22.

This operating mode is maintained, as long as the level measured by the system 23 of VOCs released into the atmosphere remains below a tolerance threshold. When the level of VOCs released exceeds this threshold, it appears that the filtration device 1 no longer fulfills its function, due to the saturation of the adsorption agents which must be regenerated.

To this end, the recovery installation comprises a desorption or regeneration circuit, designated as a whole by the reference 25.

According to the example illustrated, the desorption or regeneration circuit 25 comprises a pipe 26 which connects the outlet 22 of the filtration device 1, said main, via a condenser 27, to a vacuum pump 28. The pipe 26 is, moreover, equipped with two shut-off valves 29 and 30 located on either side of the condenser 27. Of course, the condenser is connected, by a pipe 31, to a tank 32 for recovering condensates. According to the example illustrated, the condenser 27 is connected upstream of the vacuum pump 28. However, in order to ensure condensation at atmospheric pressure, the condenser 27 could be connected downstream of the vacuum pump 28 at the outlet of the latter.

In order to reduce as much as possible the VOC emissions during the desorption phase of the main filtering device 1, the desorption circuit preferably, but not strictly necessary, includes as a means of recovering VOCs in addition to the condenser 27, a second filtration device, called secondary 35, with VOC adsorption agents. Preferably, the secondary filtration device 35 is a filtration device according to the invention and has a lower adsorption capacity than that of the main filtration device 1. In addition, the adsorption agents, used by the secondary device 35 are chosen to recover the non-condensable VOCs. It should be noted that the secondary recovery device 35 could have a capacity equal to that of the main recovery device 1. The secondary filtration device 35 is then connected, on the one hand, to the inlet by a pipe.

36 at the outlet of the vacuum pump 28 and, on the other hand, at the outlet to an outlet pipe in the open air 37, as well as, via a pipe 38 to the pipe 26 of inlet of the condenser 27, between the valve 29 and the condenser 27. The pipes 37 and 38 are, in addition, each equipped with a shut-off valve, respectively 39 and 40. Thus, when the main filtration device 1 is saturated, the installation of suction is placed in a desorption phase. The main filtration device 1 is then isolated, on the one hand, from the source effluent to be treated 21 by closing a valve 45 placed on the inlet pipe 20 and, on the other hand, the external environment by closing a valve 46 placed on the outlet pipe 22, downstream of the connection of the pipe 26 with respect to the main filtration device 1. Furthermore, the valves 29, 30 and 39 are open, while the valve 40 is closed. During the desorption phase, the adsorption agents are brought to desorption temperature via the reheating chamber 3 and the fluid 17 which is heated by the resistors 16. Taking into account the phenomena of convection and the diameter of the tubes filtration 4, a homogeneous temperature is then established in the charge 8 of adsorption agents. In conjunction with this heating, the vacuum pump 28 established within the main filtration device 1 a relative vacuum which promotes desorption. The VOCs thus released by the main filtration device 1 then pass through the condenser 27 where the condensable VOCs are recovered by the tank 32 while the noncondensable VOCs are conveyed by the vacuum pump 28 to the secondary filtration device 35 at which they will be adsorbed. Thus, it is possible to obtain, at line 37, a VOC release close to zero.

It should be noted that during the phase of use in filtration mode of the main filtration device 1, the secondary filtration device 35 can also be desorbed. To this end, the installation then comprises a pipe 47 connecting the outlet pipe of the vacuum pump 28 to the inlet pipe 20. The pipe 47 is equipped with a valve 48. Similarly, the part of the pipe 36, located between the connection of the pipe 47, is controlled by a valve 49.

Thus, during the adsorption phase at the main filtration device 1 and the desorption of the secondary device 35, the valves 45, 48, 46, 40 and 30 are open, while the valves 29, 39 and 49 are closed. The secondary filtration device 35 is further heated and the vacuum pump 28 establishes a relative vacuum within the filtration device 35 and the desorption of the adsorbers of the secondary filter 35 occurs, as has been described for main filter 1.

According to the invention, the heating means are not necessarily incorporated into the filtration device 1. Thus, FIG. 3 illustrates an exemplary embodiment according to which the reheating chamber 3 is equipped with means 50 for connection to pipes, not shown, for circulation of a heat transfer fluid. According to the example illustrated, the connection means 50 are constituted by flanges.

Similarly, according to the invention, the tubes 4 do not necessarily have a cylindrical shape of revolution, they could also have a rectangular or other section. Similarly, the tubes 4 are not necessarily straight and may, for example, have a "U" shape, the two collecting chambers then being on the same side of the filtration body. In addition, according to the examples illustrated, the tubes 4 stop at the level of the walls 5 sealingly delimiting the reheating chamber 3. However, in accordance with the invention, the tubes 4 could pass through the walls 5 and be simply closed, at each of their ends, by means of retention of the adsorption agents permeable to the gaseous effluents to be treated.

Various other modifications can be made to the invention without departing from its scope.

Claims

1 - Filtration device, for the recovery of volatile organic components in particular, comprising a filtration body (2) which delimits at least one reheating chamber (3) crossed in leaktight manner by at least one filtration tube (4) containing regenerable adsorption agents (8) and which is equipped with connection means (11) to an effluent circuit to be treated, characterized in that it comprises integrated means (15) for heating the reheating chamber (3 ).

2 - filtration device according to claim 1, characterized in that the integrated heating means (15) comprise at least one electrical resistance (16) and in that the reheating chamber contains a fluid (17).

3 - filtration device according to claim 1 or 2, characterized in that the filtration body (2) comprises a bundle of filtration tubes (4) which sealingly pass through the heating chamber (3) and which open at the level from each of their ends in a collecting chamber (7). 4 - filtration device according to one of claims 1 to 3, characterized in that the filtration tubes (4) have a substantially circular cross section with an internal diameter between 50 and 100 mm.

5 - A filtration device according to one of claims 1 to 4, characterized in that the adsorption agents (8) comprise particles of activated carbon. 6 - filtration device according to one of claims 1 to 5, characterized in that the adsorption agents (8) comprise resins of the absorbent type.

7 - Filtration installation for the recovery of volatile organic components comprising a main pipe (20) for circulation of effluents to be treated and means (1) for recovery of volatile organic components, characterized in that the recovery means comprise at least a filtration device (1) according to one of claims 1 to 6, which is connected to the pipe (20) for circulation of effluents to be treated.

8 - Filtration installation according to claim 7, characterized in that it comprises a desorption circuit (25) connected to the filtration device (1) said main and equipped with means (27, 35) for recovering the VOCs released by the main filtration device (1) during a desorption phase. 9 - Installation according to claim 8, characterized in that the desorption circuit (25) comprises means (25) for establishing a relative vacuum within the main filtration device (1). 10 - Installation according to claim 8 or 9, characterized in that the VOC recovery means comprise at least one condenser (27).

11 - Installation according to one of claims 8 to 10, characterized in that the VOC recovery means comprise at least one secondary filtration device (35) containing VOC absorption agents.

12 - Method for regenerating a device (1) of filtration with regenerable adsorption agents (8) of VOCs, characterized in that it consists, to ensure desorption of the adsorption agents (8), to be heated by thermal conduction adsorption agents (8) of VOCs and to establish a relative vacuum within the filtration device (1).