FR2784305A1 - Separation and recovery apparatus for liquid particles from gaseous effluent comprises opening defining reduced section of gas flow passage, with impact wall above opening - Google Patents

Abstract

At least one opening defines a first reduced section of the gas flow passage (5), with at least one impact wall (6) above the opening, slightly inclined to the horizontal. The impact wall defines a second section (14) offset to the first. There are also means of recovering (8) and evacuating (12) the liquid on the impact wall and at least one outlet (15) for the liquid-free gas. The diaphragm containing the opening includes a first wall (3) installed perpendicular to the longitudinal axis of the shaft, inclined at less than 50 deg and parallel to the impact wall. The device includes means of regulating the size of the opening, by means of a regulating plate (4) mounted to slide parallel to the first wall. The outlet for the gas is offset vertically relative to the second section. The means of recovering and evacuating the liquid include at least one trap (8) at the lower end of the impact wall, with a pipe (12) connected to the trap. The first wall includes a gutter where the pipe is interrupted.

Description

 Device for separating and recovering liquid particles contained in a gaseous effluent.

 The field of the invention is that of devices and installations for the treatment of gaseous effluents.

 The invention relates more precisely to a device specially designed for removing a gaseous effluent from the liquid particles which it contains.

 The invention finds its application for the treatment of air coming from industrial premises in which water is used such as in particular paint booths.

 The objective of such a device is to obtain an air flow free of liquid particles making it possible to evacuate the recovered water and to avoid its re-entrainment by the air.

 Such devices for separating and recovering liquid particles in a gaseous effluent are installed on the evacuation ducts of these effluents.

A distinction is made between devices treating lateral flows and devices treating ascending flows. The present invention relates to a device intended to treat a gaseous effluent transiting according to an ascending current in a sheath.

 There are mainly two types of technology in the state of the art for removing a gaseous effluent from the liquid particles it contains, based on the principle of impaction.

 The first of these techniques consists in passing the flow of air loaded with liquid particles through a network of curved parallel plates arranged in a sheath, the flow of air moving horizontally therein.

 The plates used have an "S" shape suitable for stopping the liquid particles contained in the gas stream. In order to recover the liquid stopped by these plates, the latter are equipped with small gutters in which the retained water flows by gravity.

 Such a technique has many drawbacks, among which the following may be mentioned. Firstly, such a solution only treats horizontal air flows and not upward air flows. Indeed, it will be understood that if one used such a technique with an ascending air flow, gutters open downwards would be completely ineffective in recovering the liquid retained by the plates.

 Secondly, to be effective, the plates used must be relatively close to one another. In practice, the plates constituting such devices are located 2 to 3 cm from each other. However, the liquid particles contained in the gaseous effluents to be treated can also contain sticky particles - this is particularly the case in the treatment of effluents from paint booths - which are deposited on the plates at the same time as the liquid which contains. Consequently, it is periodically necessary to clean these plates. However, the architecture of "S" plates, mentioned above, close to each other, makes the maintenance of the device difficult and long.

 Finally, it should be noted that the average speed of passage of the gaseous effluent to be treated through this plate must be low, in practice less than 4 meters per second. It is therefore necessary to use a large number of plates distributed over a large front surface.

 Another state-of-the-art technique makes it possible to treat the ascending gas streams through at least two levels of plates installed perpendicular to the direction of flow of the air flow and arranged in staggered rows.

These plates form as many impact plates making it possible to stop the particles of liquid.

 However, such a device also shows a certain number of drawbacks.

 Firstly, the staggered positioning of the trays cannot prevent the establishment of preferential paths for the flow of the air flow along which the latter does not meet the trays. The part of the flow following these preferred paths therefore remains charged with liquid particles and the effluent leaving the device is therefore poorly rid of the particles which it contained at its inlet.

 In addition, the drops of water stopped by the plates are badly evacuated because they are horizontal. These liquid particles are then liable to be re-entrained by the gas stream.

 It will also be noted that such a technical solution requires most of the time the use downstream of the system described above.

 Finally, it will be noted that the space between the plates is greater than that used in the technique described above, but that the number of levels of plates used is generally greater than 2, which implies that the maintenance of such a device is not easy.

 The objective of the present invention is to provide a device for the separation and recovery of the liquid particles contained in a gaseous effluent which does not have the drawbacks of the two prior art devices described above.

 In particular, one of the objectives of the invention is to propose such a device which can be used to treat an updraft of gaseous effluent.

 Yet another objective of the present invention is to disclose such a device which ensures very good evacuation of the liquid and limits the re-entrainment of the liquid particles in the gas flow.

 Yet another objective of the present invention is to provide such a device with easy access which makes its maintenance easy.

 These various objectives are achieved thanks to the invention which relates to a device for separating and recovering liquid particles contained in a gaseous effluent transiting in an upward current in a sheath, characterized in that it comprises means having at least one opening. forming a diaphragm defining a first reduced section for the passage of said gaseous effluent, at least one impaction wall installed above said opening, mounted slightly inclined relative to the horizontal and on which said particles of liquid will impact, said impaction wall defining a second passage section of said gaseous effluent offset with respect to said first passage section, means for recovering and discharging the liquid coming from said impaction wall and at least one outlet for the gaseous effluent basically got rid of its liquid particles.

 Unlike the devices of the prior art, the present invention proposes to use only one opening forming a diaphragm followed by a single impaction plate. Such a design greatly facilitates the production of this type of device.

 Preferably, said diaphragm means include a first wall installed essentially perpendicular to the longitudinal axis of said sheath. Note however that one can also consider providing walls of the sheath forming a narrowing, and therefore not requiring the use of such a first wall.

 It will be understood that for the proper functioning of such a device, the impaction wall must be inclined to allow the flow of the liquid which it retains towards the recovery and evacuation means. However, according to a preferred variant, the first wall is also slightly inclined. It will be noted that in the present description the terms "slightly inclined" are understood to mean an inclination less than 50.

 Also according to a preferred variant, the wall having the opening forming a diaphragm and the impaction wall are essentially mounted parallel to each other.

 In order to adjust the speed of passage of the gaseous effluent through the passage section defined by the opening forming a diaphragm, the device according to the invention advantageously includes means making it possible to adjust the size of the opening forming a diaphragm defining this first passage section. We can consider making these means in different forms. However, for the sake of simplicity, these means include an adjustment plate mounted to slide parallel to said first wall.

 Also according to a preferred variant of the invention, the outlet of the gaseous effluent is offset vertically with respect to the second passage section.

 Advantageously, said means for discharging and recovering the liquid include at least one chute mounted at the lower end of said impaction wall.

 Also advantageously, said means for evacuating and recovering the liquid include at least one pipe connected to said chute.

 The invention, as well as the various advantages which it presents, will be more easily understood thanks to the description which follows of a nonlimiting embodiment of the latter given with reference to the single figure which represents a perspective view. of such an embodiment.

 With reference to this single figure, a gaseous effluent charged with particles of liquid, symbolized by the gray arrow 1 flows in a sheath 2 which, in the case of the present embodiment, is of rectangular section but which may have another section shape in other embodiments.

 The device according to the invention comprises a first wall 3 disposed essentially transversely to the longitudinal axis of the sheath 2 and having an opening forming a diaphragm defining a reduced section 5 for the passage of the gaseous effluent. This wall 3 is lined with a sliding plate 4 making it possible to reduce the size of the opening forming a diaphragm. By actuating the plate 4, it is thus possible to play on the speed of passage of the gaseous effluent through the passage section 5. It will be noted that the plate 3 is mounted slightly inclined relative to the horizontal.

 The device shown also comprises an impaction plate 6 installed above the plate 3 so as to come opposite the opening forming a diaphragm. This impact plate, which inevitably meets the gaseous effluent loaded with liquid particles having passed through the passage section 5, is mounted slightly inclined and defines a second passage section 14.

 At the lowest end of this impaction plate 6 is provided a chute 8 constituted by an essentially horizontal plate 10 and an essentially vertical plate 11 connected to a discharge pipe 12.

 Finally, it will be noted that the device also includes an upper outlet 15 for the gaseous effluent which is provided offset relative to the second section 14 for passage of the effluent.

 The operation of the device is as follows.

 The gaseous effluent charged with particles arrives in the lower part of the sheath 2 in an upward flow. It then passes through the passage section 5 which has a reduced size compared to the section of the sheath itself. This reduction in section results in an increase in the speed of the gaseous effluent which strikes the impaction plate 6. This impaction plate forces the flow of gaseous effluent to change direction abruptly. Under the effect of inertia, the liquid particles it contains impact on the impaction plate 6 to form a liquid film symbolized by the arrow 7 in the figure.

 The impaction plate 6 being inclined, the film of liquid formed thereon is directed under the effect of gravity towards the chute 8. This flow is favored by the gas flow which accelerates it since it moves also in the direction of the gutter 8. The water collected in the gutter 8 is discharged through the pipe 12 to a liquid outlet 13 of the installation.

 The chute 8 present is positioned in such a way that it makes it possible to divert the current lines from the gas flow while allowing the liquid not to be re-entrained by it.

 The gaseous effluent then passes through the second passage section at a determined speed, then leaves the device 2 according to the invention via the outlet 15.

In order to block the last particles of liquid contained in the gas flow, this outlet is advantageously offset with respect to the passage section 14.

For this purpose, it will be noted that the plate 3 forms an elbow 9 at the level of which the pipe 12 is interrupted, which makes it possible to recover the last drops blocked by the upper wall 16 of the device.

 The embodiment of the invention thus described does not aim to reduce the scope of the latter, consequently numerous modifications can be made to it without departing from its scope.

Claims (10)

 CLAIMS 1. Device for separating and recovering liquid particles contained in a gaseous effluent transiting according to an ascending current in a sheath, characterized in that it comprises means having at least one opening forming a diaphragm defining a first reduced passage section ( 5) of said gaseous effluent, at least one impaction wall (6) installed above said opening, mounted slightly inclined relative to the horizontal and on which said particles of liquid will impact, said impaction wall (6) defining a second passage section (14) of said gaseous effluent offset with respect to said first passage section (5), means for recovering and evacuating (8,12) the liquid coming from said impaction wall and at least one outlet (15) for the gaseous effluent essentially freed from its liquid particles. 2. Device according to claim 1 characterized in that said diaphragm means include a first wall (3) installed essentially perpendicular to the longitudinal axis of said sheath. 3. Device according to one of claim 1 or 2 characterized in that said first wall (3) is inclined according to a degree of inclination less than 50. 4. Device according to any one of claims 2 or 3 characterized in that said first wall (3) and said impaction wall (6) are essentially parallel. 5. Device according to any one of claims 1 to 4 characterized in that it includes means for adjusting the size of said opening forming a diaphragm defining said first passage section (5). 6. Device according to one of claims 2 to 4 and according to claim 5 characterized in that said means for adjusting the size of said opening forming a diaphragm include an adjustment plate (4) slidably mounted parallel to said first wall (3 ). 7. Device according to any one of claims 1 to 6 characterized in that said outlet (15) of the gaseous effluent is offset vertically by said second passage section (14). 8. Device according to any one of claims 1 to 7 characterized in that said means for evacuating and recovering the liquid include at least one chute (8) mounted at the lower end of said impaction wall (6) . 9. Device according to claim 8 characterized in that said means for discharging and recovering the liquid include at least one pipe (12) connected to said chute (8). 10. Device according to claim 9 characterized in that said first wall (3) has a channel at which said pipe (12) is interrupted.