FR2693382A1 - Permanent tube and shell filter for diesel engine exhausts - to extract dust and residues from fuel additives without coking up the filter - Google Patents

Abstract

Filter for cleaning engine exhaust, comprises a bundle of filter tubes fixed in a shell and an end plate closing one end of at least some of the tubes which can be separated from the tube bundle. Either the end plate or the tube bundle is mounted to rotate relative to the other. The end plate contains openings which match with the end of some of the filter tubes. The rotating tube bundle turns about a central axis. USE/ADVANTAGE - Cleaning of exhaust gases from motors such as diesel engines. In particular extracting dust such as submicron carbon particles and residues from fuel additives. The device is a permanent filter for engine exhaust, which does not block up with residues from the catalytic reaction of the exhaust.

Description

FILTER FOR PURIFICATION OF ENGINE FUMES,
ESPECIALLY DIESEL ENGINES
The invention relates to a filter for the purification of fumes from engines, more particularly from diesel engines.

 We know that diesel engines tend to emit very dusty fumes. These dusts are generally carbonaceous submicron particles.

 These dusts are messy but in addition it has been shown that they can be toxic. The purification of diesel engine fumes is therefore a major problem.

 Filters have been proposed for this purpose which are generally honeycomb structures with filtering walls, made of ceramic material.

 These filters, although effective, nevertheless have a drawback in terms of their regeneration in service.

 Indeed, to burn the collected particles, it is necessary to bring the filter to high temperatures which are detrimental to the good performance of the materials constituting the filter.

 Certainly, fuel additives are known, the role of which is to decrease the quantity of particles produced by the engine and also to lower the temperature necessary for the burning of these particles, thanks to a catalytic action of the residues of these additives. These residues are metal oxides and the additives are described in particular in US Pat. Nos. 2,622,671, US 4,568,357, US 4,655,037.

 When using fuels comprising these additives, there is a progressive accumulation of residues in the filter, which means that it must be replaced after a relatively short time.

 The object of the invention is to solve this problem by providing a filter allowing efficient and easy removal of these residues.

 For this purpose, the filter, according to the invention, for 1 purification of engine smoke, is characterized in that it comprises a bundle of filter tubes and a flange closing the ends on the same side of at least part tubes.

Other characteristics, details and advantages of the invention will be better understood on reading the description which will follow made with reference to the accompanying drawings in which
- Figure 1 is a sectional view of a filter according to the invention;
- Figure 2 is a front view of a flange for fixing the tubes of a filter according to the invention;
- Figure 3 is a front view of a flange for fixing the tubes of a filter according to another embodiment of the invention;
- Figure 4 is a front view of a flange closing the tube ends of a filter according to the invention.

 If we refer to Figure 1, the filter of the invention consists of a bundle of filter tubes (1).

 These tubes are kept fixed in flanges (2), the whole being able to be placed in a cartridge or a case (3).

 The ends of the same side of the tubes are closed by a flange (4). This flange (4) is mounted in such a way that it can be separated from the bundle of tubes when cleaning them.

 It should be noted that, according to the various embodiments of the invention, the flange (4) closing the tubes can be integral with the bundle of tubes (1) In such a case, the flange (4) can be kept integral with the bundle of tubes via a fixing flange 2 for example, and by any known means.

 The flange 4 can also be rotatably mounted relative to the tube bundle, the latter being kept fixed, or vice versa.

 We can also imagine an assembly in which the two are rotatable with respect to each other.

 In a case like that of Figure 1, the flange (4) is mounted around a central axis (5) solid or hollow which in the latter case can be closed by a plug (11).

 Still as in the case of FIG. 1, it is possible to design a system in which the bundle of tubes is fixed and the closing flange (4) is mounted on the axis (5).

 In order to ensure tight sealing of the tubes by the flange (4), a spring system can be provided. A spring can thus be mounted around the axis (5) and rest at one of its ends, on a support washer fixed to this axis by gluing or using a pin. The other end of the spring acts via a spacer on the flange (4), which allows the spring to be placed in a cold zone.

 The tubes forming the bundle can be in any number.

 Likewise, they can also be arranged in any way. FIG. 2 illustrates an embodiment in which the tubes are arranged in radiating arrangement, with respect to a central axis, in which case the flange (2), for example circular, is provided with notches or orifices (6) in which house the tubes (1).

 FIG. 3 illustrates another embodiment allowing mounting at maximum density in a cylindrical space.

 The orifices (6) are no longer distributed along the radii of the flange (2) but along the cords of the circumference of the latter.

 The closing flange (4) can be full or, as it appears in FIG. 4, it can have orifices (7) intended to come opposite the end of a part of the filter tubes.

 In the latter case, the orifices (7) must be arranged in such a way that by displacement of the closing flange (4), and more particularly by rotation, the end of each tube can at least once during the entire duration of the displacement come next to at least one opening. For example, if the tubes are arranged in radial mounting, a set of orifices (7) arranged in the same way may be provided on a radius of the closing flange (4).

 For rotary mounting of the beam or the flanges, these are provided with a central opening (12) for the passage of the axis.

 With regard to the nature of the materials used, the filter tubes may be made of any material capable of satisfying the following conditions. They must be able to retain at least 85%, preferably at least 90%, of the particles of diesel fumes and additive residues. They must also cause a minimum pressure drop. They must also be able to withstand temperature spikes that can exceed 14000C.

 Finally, the material of the tubes, or possibly the additives, must be chosen in order to avoid any reaction between the material and the additive residues.

 Ceramic tubes are well suited for this application. Mention may more particularly be made of mullite or mullite-cordierite tubes.

 It is also possible to use ceramic tubes with a thin internal coating, this coating having low porosity and being supported on a tube body of greater porosity.

 Tubes of this type offer a large filtration capacity without causing a significant pressure drop.

 According to an advantageous variant, the tubes can have or receive a porous external coating containing a catalytic phase for the oxidation of gaseous polluting elements such as, for example, CO or unburnt hydrocarbons constituted by residues of fuel, engine oil and the burning of particles.

 The catalytic phases are those used in the manufacture of catalytic deposits for gasoline engine exhaust gases (precious metals, metal oxides and perovskites ...).

 The flanges may be of any suitable material, in particular ceramic, to allow the tubes to be maintained at any temperature and to ensure the tightness of the system. The flange (4) must be made of a waterproof material.

 In operation, the exhaust gases arrive via a pipe (8) in the direction of the arrow (9) and they enter each of the filter tubes (1).

 They are filtered as they pass from the inside to the outside of the tubes. The filtered gases are discharged through an outlet (lu).

 Additive residues combined with particles cause them to burn continuously, or at programmed intervals depending on the regeneration systems chosen: electric heating, oil burners, exhaust gas valve.

 The additive residues then gradually accumulate in the tubes, which requires cleaning at regular intervals to maintain the filtration capacity and the pressure drop at a suitable level.

 This cleaning can be done in different ways.

 In the case, for example where the flange (4) is full, cleaning is done by separating the flange (4) from the tube bundle.

 The tubes are then opened and can be cleaned by blowing with compressed air. This can be done during regular maintenance, for example every 10,000 or 50,000 km.

 The device of the invention can also allow continuous cleaning. This is the case when the flange (4) is provided with orifices and the latter or the bundle of tubes are mounted to rotate relative to one another. It is then possible to provide a compressed air injection system, to which the flange is controlled, which makes it possible to inject air via the flange (4) into each tube coming opposite an orifice of the flange during the respective rotation thereof, with respect to the tube bundle.

 In this case, the residues are collected in an enclosure provided for this purpose to avoid their rejection into the atmosphere.

 It can therefore be seen that the device of the invention, by its design, thanks to the presence of a closing flange of the type of that described, can be cleaned in a complete and simple manner.

Claims (9)

1 - Filter for purifying engine smoke comprising a bundle of filter tubes kept fixed in a box, characterized in that it further comprises a flange closing the ends on the same side of at least part of the tubes and separable of said bundle of tubes. 2 - Filter for purifying engine smoke, comprising a bundle of filter tubes, characterized in that it further comprises a flange closing the ends on the same side of at least part of the tubes and separable from said bundle of tubes , one of the flange or of the bundle being rotatably mounted relative to the other. 3 - Filter according to claim 1, characterized in that one of the flange or the beam is rotatably mounted relative to the other. 4 - Filter according to one of the preceding claims, characterized in that the flange has openings which can come opposite the end of a part of the filter tubes. 5 - Filter according to one of claims 2 to 4, characterized in that the filter tube bundle is rotatably mounted relative to a central axis.  6 - Filter according to one of the preceding claims, characterized in that the filter tubes are made of ceramic material, in particular mullite or mullite - cordierite. 7 - Filter according to one of the preceding claims, characterized in that the filter tubes have an internal coating of low porosity based on a tube body of greater porosity. 8 - Filter according to one of the preceding claims, characterized in that the filter tubes are coated on their wall with a catalytic phase of oxidation of gaseous polluting elements. 9 - Filter according to claim 4 and the urea of claims 1 to 8, characterized in that it comprises an air injection system in the filter tubes via the aforementioned flange.