FR2650627A1 - DEVICE FOR REMOVING CARBON PARTICLES CONTAINED IN EXHAUST GASES OF HEAT ENGINES - Google Patents

Abstract

Device for removing carbonaceous particles contained in the exhaust gases of heat engines, consisting of a filter element 3 or 4 consisting of a casing channeling the gases and containing a filter 34 or 44 and providing a cavity which receives micro- waves of a microwave generator 6, characterized in that the generator 6 is coupled to the filter element by a tubular coupling member 7, opening through a coupling iris 37 or 47 in the casing.

Description

CARBON PARTICLE REMOVAL DEVICE

  CONTAINED IN THE EXHAUST GASES OF HEAT ENGINES

  The present invention relates to a device for eliminating.

  carbonaceous particles contained in engine exhaust

  thermal, consisting of a filter element consisting of a.

  envelope, channeling the gases and containing a filter and sparing - a

  cavity that receives microwaves from a microwave generator.

  It has been proposed to remove the carbonaceous particles contained in the exhaust gases of a diesel engine by a filter element mounted on  5 an exhaust gas conduit, containing a particle filter and associated with a micro generator. -generating waves, through a

  wave conductor, waves in a cavity formed in said element.

  The combustion of carbonaceous particles deposited on a ceramic filter is made possible by the action of a microwave electromagnetic field

  under very precise conditions of implementation.

  Patent FR-A 2 588 610 proposes two solutions for obtaining the combustion of carbonaceous particles either by passing them or by making them stay in the areas of the resonator or the field.

electromagnetic is maximum.

  The object of the present invention is to provide a device for removing particles of the type described above and whose guidance system

  wave allows an optimization of the 'energy transfer.

  The device according to the invention is characterized in that the generator is coupled to the filter element by a coupling member

  tubular, opening through a coupling iris in the envelope.

  According to one characteristic, the device comprises two filtration elements in parallel and the coupling member whose shape is that 2 - of a T consists of a main guide and derived guides' connected to the envelopes of the elements. filtration, these guides being metallic and

of rectangular sections.

  According to one characteristic, microwaves penetrate into envelopes

  by coupling irises which have isolation elements.

  According to one characteristic, the coupling member has from I to 3 pistons

Okay.

  The invention will now be described in more detail with reference to an embodiment given by way of example and represented by the appended drawings in which - FIG. I is an embodiment of the device according to the invention, - Figures 2 and 3 show a component of the device in elevation

and in right view.

  Referring to Figure 1, we see a motor -I whose pipe. exhaust gas 21 dwvise in two branches 22 and 23 on which are mounted two filtration elements 3 and 4 operating in parallel. The gases leaving the elements 3 and 4 are channeled by pipes 52 and 53 which connect to a pipe 51. The direction of circulation of the gases is

represented by arrows.

  The filter element 3 is composed. an outer casing 31 channeling the gases. It is connected upstream to the pipe 22 and in

  downstream to the pipe 52 and it contains a monolith filter 34.

  The filter element 4 is similarly composed of an outer casing 41 channeling the gases. It is connected upstream to the pipe 23 and downstream to the pipe 53 and it contains a filter.

monolith 44.

  Filters 34 and 44 are filters known per se, made of ceramic, with

  honeycomb structure and possibly supporting catalysts.

  Each external envelope 31 and 41 is of cylindrical or elliptical section. The monolith filter 34 or 44 is thermally insulated at its periphery. Its diameter can be substantially equal to that of the envelope and its length adapted to form inside the envelope two cavities, one 35 or 45 upstream, the other 36 or 46

downstream.

  Microwaves are sent to the upstream cavities 35 and 45.

  The device comprises a microwave generator 6 associated with a coupling member 7 of general T shape supplying microwave

cavities 35 and 45.

  The coupling member 7 consists of a main guide 71 and guides

  derivatives 72 and 73 having a tubular shape and a rectangular section.

  It allows the propagation of the only mode - fundamental at 2.45 GHz noted TE1. The dimensions of the main guide section are marked a and b. As an indication, these dimensions are 86 x 43 mm. The axis of this main guide is parallel to the axes of gas flow in the filters. We could easily carry out an equivalent assembly with the main guide perpendicular to the axes of gas circulation. We would then be with an elbow called "Plan H" while the example chosen highlights

work a bend called "Plan E".

  The main guide 71 is associated with 1, 2 or 3 tuning pistons (2 in the example chosen) which can sink more or less into the guide 71 perpendicularly to the axis thereof. These pistons provide variable susceptances. As an indication, the distance between the pistons is advantageously chosen in the vicinity of Ag / 4 or 3> g / 8 ot X g is

the guided wavelength.

  The main guide 71 is connected to two derivative guides 72 and 73 of tubular shape and of rectangular section. These two guides are coaxial and extend perpendicular to the axes of circulation of the gases in the elements 3 and 4. The small side b 'of the section of the lateral guides 72, 73 is -approximately equal to half of the small side b of the guide principal 71. The large sides with sections 71, 72, 73 are equal. The wall at the junction of the main guide and the derived guides has a divergent shape 76. This wall leaves a passage for

width b '= b / 2.

  The junction of the derived guides with the main guide can also be carried out from waveguides bends if care is taken to maintain the shapes and dimensions of the straight section during curvature, the value of the radius of curvature being, moreover, less critical for

obtaining good performance.

  The lateral guides 72 and 73 open into the envelopes 31 and 41 at the level of the cavities 35 and 45 (delimited by the ceramic filters) by coupling irises 37 and 47 respectively. These irises are orifices of smaller section than that of the derived guides. The shape and dimensions of these irises are chosen so as to. transfer the most

  of microwave energy in the resonator - charged by the filter.

  In the case of a carbon loaded filter, it has been observed that a very efficient energy transfer is obtained for a rectangular iris whose short side P of the rectangle is equal to b / 2 and whose long side is precisely adjusted to measurement bench to minimize the fraction of reflected power. A value close to 48 mm ('a / 2) gives good results

  for the monolith and the cavity cited as an example.

  - The coupling irises 37 and 47 have isolation elements 38 and 48 which allow propagation without attenuation of the microwaves, but

  prevent the passage of carbonaceous particles towards the derived guides.

  These elements 38 and 48 are, for example, ceramic plates or discs. A controlled switching valve 24 directs. the exhaust gases escape towards one or the other of the filters 34 or 44 subjected to the microwaves. In this way, one filter is charged with particles while the other filter

  is in the phase of microwave elimination of the particles.

  A valve system is advantageously provided in the coupling member 7. It makes it possible to send all of the microwave power to the filtering element in regeneration by obstructing the lateral guide

  concerning the other filter element.

  -This constructive provision is not limiting of. fact that the exhaust gases can be temporarily diverted through a bypass duct without a filter by cleaning a single main filter

as previously described.

  The device which has just been described has the following advantages: It is simple and therefore inexpensive to manufacture. It can be produced in t81e without any particular tolerance on the dimensions, - Optimizing the transfer of energy to the resonators can be done simply by adjusting the depression of the tuning pistons. With the dimensions recommended for the system, one can obtain an almost total energy transfer by specific positions of the pistons, which makes it possible to minimize the microwave power necessary for regeneration and therefore the weight of the generator supply (tube magnetron).

R E Y E N D I C A-T I O N S

  1 ') Device for eliminating carbonaceous particles contained in the exhaust gases of heat engines, consisting of a filtration element (3 or 4) constituted by an envelope channeling the gases and containing a filter (34 or 44) and providing a cavity which receives microwaves from a microwave generator (6), characterized in that the generator (6) is coupled to the filter element by a tubular coupling member (7), opening out by a coupling iris

(37 or 47) in the envelope.

  2 ') Device according to claim 1, characterized in that it comprises two filtration elements (3 and 4) in parallel and that the coupling member - (7) whose shape is that of a T consists a main guide (71) and derived guides (72, 73) connected to the casings of the filtration elements, these guides being metallic and

of rectangular sections.

  3) Device according to claim 2, characterized by. the fact that the wall of the coupling member has at the junction of the guide

  main and derived guides a divergent form (76).

  4-) Device according to claim 3, characterized in that the junction of the main guide with the side guides can be achieved

  using angled waveguides.

  e) Device according to any one of the preceding claims,

  characterized by the fact that the microwaves penetrate into the envelopes (31, 41) by coupling irises (37, 47.) which have

  isolation elements (38, 48).

  6-) Device according to any one of the preceding claims,

  characterized in that the coupling member (7) has from 1 to

3 tuning pistons (74, 75).

  7th) Device according to any of the preceding claims,

  characterized by the fact that the filter. is based on material

  refractory with low dielectric losses.

2650-627

-7-

  8) Device according to any one of the preceding claims,

  characterized by the fact that a switching valve (24) directs the gases to one or the other of the filters (34, 44) in order to always have a filter which is charged with particles and at least one another filter in the phase of elimination by microwave of particles.

  9-) Device according to any one of the preceding claims,

  characterized by the fact that a system of valves, arranged in the coupling member (7) makes it possible to send all of the power

  microwave to the regenerating filter element.