WO1985003976A1

WO1985003976A1 - Apparatus for afterburning smoke gases

Info

Publication number: WO1985003976A1
Application number: PCT/FI1984/000020
Authority: WO
Inventors: Veikko Rahikka
Original assignee: Veikko Rahikka
Priority date: 1984-03-01
Filing date: 1984-03-01
Publication date: 1985-09-12
Also published as: AU4116385A; WO1985003977A1; EP0205420A1; EP0207943B1; EP0207943A1

Abstract

Apparatus for afterburning of smoke gases, e.g. exhaust gases of the combustion engine. The apparatus consists of a turbulence chamber (1) to which the gas to be additionally burnt is tangentially brought. The chamber is cylinder-symmetrical and widening from the edges towards the centre. Its axis (A-A) has been connected with an air channel (2), in the middle of which wall (11) there is an opening (3), through which the mixture of gas and air removes from the turbulence chamber (1). The said opening (3) has been preferably formed to an intermediate chamber (31) that comprises a right cylindrical space. This has been connected to the exhaust chamber (4) that is a cylinder-symmetrical space being confined both to the conical outer wall (41) and the inner wall (42) and which exhaust chamber (4) has been connected with a ring-shaped channel (5) or opening to the actual combustion chamber (6). A gas turbulence that begins to burst through the centre opening (3) to the intermediate chamber (31), is formed in the turbulence chamber. The turbulence is concentrated close to the mantle of the intermediate chamber whereby a low-pressure field in direction of the axis (A-A) is formed in the middle of the chamber. Through the air channel (2) air is absorbed to the centre of the axially advancing turbulence and is effectively mixed with the turbulence. The temperature of the smoke gas turbulence is most often sufficiently high for generation of selfignition, whereby on bursting of the gas turbulence widening to the turbulence chamber (4) it at the same time ignites. The gas turbulence advancing in the exhaust chamber along the outer wall (41) further absorbs air from the second air channel (14), it is widened and steered through the exhaust chamber (4) and the outlet channel (5) to the combustion chamber (6) where the final burning takes place.

Description

APPARATUS FOR AFTERBURNING SMOKE GASES

The object of this invention is an. apparatus for afterburning of smoke gases, for instance for afterburning of exhaust gases of a combustion engine, which apparatus consists of a turbulence chamber, to which the gas to be additionally burnt is tangentially brought, which chamber is a cylinder-symmetrical widening at the edges towards the centre and to the axis of which there has been connected an air channel, at the centre of the wall of this chamber there is an opening, through which the mixture of gas and air removes from the turbulence chamber. The apparatus can be connected to the exhaust manifold or exhaust pipes of the engine.

There are known apparatus for burning of smoke or exhaust gases, among other things the British and American patents of the applicant GB 1,358,743 and US 4,191,132. The second patent is concerned with the combustion chamber of burning gaseous substance with an additional combustion chamber, where the gases to be burnt are brought to turbulence. The proper combustion chamber has been formed from a cylinder-shaped solid of revolution, to the outer ring of which the gases are tangentially led through one or more nozzles. Then a lowpressure is brought up to centre of the chamber, to which burning air is led from outside the chamber through the first centre opening. From this combustion chamber the gas and air mixture is led influenced by suction or pressure through the second centre opening to one or more additional combustion chambers. In each chamber, thanks to V-shaped steering surfaces, two different turbulences, a developing and a reducing turbulence are formed. The- burning takes place effectively as the turbulences are partly mixing with_. each other when the gases flow through the centre opening and/or the tangential connection chamber to the next chamber. The principle has been adapted especially for a central heating kettle, where the mixture of fuel and burning air led from the oil burner opening will be led to the combustion chamber and further to the additional chambers, from which the gases remove through the smoke channel .

The British patent GB 1,358,743 is concerned with the oxidizing or afterburning apparatus of exhaust gas, which apparatus is particularly determinded for combustion engines. A turbulence of mixing chamber widening towards the centre belongs to this, and the exhaust gases are led to this chamber tangentially through one or more nozzles and are brought in this way to revolving motion. The additional air is led through the air opening at the axis of the mixing chamber. The mixture of gas and air is led out from the mixing chamber through the opening on the opposite side of the air opening to the ball-shaped combustion chamber. The ignition devices have been preferably placed to this in order to effect the burning of the gas.

The problem with the apparatus in accordance with the British patent is among other things the fact that the apparatus does not function in a satisfying way with the small numbers of revolution of an engine. The pressure waves of the exhaust gases cause occasional disappearing of the lowpressure from the centre axis of the chamber, when the supply of the additional air is disturbed. On the other hand the combustion process may move once in a while owing to pressure fluctuations to the air inlet and to the mixing chamber. It has been noted that the ability to function especially at combustion engine operation of smoke gases or correspon¬ ding afterburning devices based on turbulence combustion can be essentially improved by shaping the apparatus in a new way. So the post-treatment apparatus can operate in a satisfying way on the wide operation area of the engine, also on idling, which in the known post-treatment apparatus has often been problematic. Additionally the design and structure of the treatment apparatus in accordance with the invention effectively damp the pressure waves or pushes occurring in the gas flow. So it also operates for example as a part of exhaust pipes of the combustion engine for its part as an effective muffler.

In the following the invention is illustrated by means of the enclosed drawings, where

Fig. 1 illustrates one embodiment of the invention as section picture seen from the side; Fig. 2 illustrates a cross-section B-B of the embodiment of Fig. 1 ; Fig. 3 illustrates another embodiment of the invention as section picture seen from the side; Fig. 4 illustrates a cross-section C-C of the embodiment ^' of Fig. 3;

Fig. 5 illustrates the third embodiment of the invention also as cross-section from the side; Fig. 6 illustrates the fourth embodiment of the invention with several treatment apparatus in a series; Fig. 7 illustrates the fifth embodiment of the invention where the air channel reaches from the turbulence chamber to the exhaust chamber.

The afterburner of smoke gases according to the invention comprises the turbulence chamber 1, the air channel 2

- υREATT' O P1 connected to it and in the middle of the wall 11 of the turbulence chamber the opening 3, the centre opening, which is preferably connected to the intermediate chamber 31. The opening 3 and the intermediate chamber 31 are followed by the exhaust chamber 4 and the proper combustion chamber 6 placed on the same main axis A-A.

The turbulence chamber 1 is a cylinder-symmtrical space that widenes at the edges towards the^* centre and the axis A-A. The first wall 10 of the turbulence chamber 1 is preferably at right angle against the axis A-A, whereas the second wall 11 is at angle *= against the axis A-A. The angle -β is 60°^ ^■=■^■< ---* 90°, preferably 75°.

The smoke gases to be afterburnt are led to the turbulence chamber 1 in tangential direction through one or more openings or nozzles. This has been arranged in the embodiment of the invention according to Fig. 1 and 2 in a way that the inlet channel 7 of the gas has been tangentially connected to the periphery of the turbulence chamber 1. The smoke gases then have in the turbulence chamber a turbulence or twist motion advancing from the periphery towards the centre and accelerating with its angle speed.

The air channel 2 has been placed to the axis of the turbul.ence chamber 1 and the inlet opening of the air channel has been connected to open air or some other suitable air or oxygen source. The outlet opening 21 of the air channel has been placed close to the centre opening 3. The cross-area of the inlet channel 7 of the smoke gases is •generally as big or at least approximately as big as the cross-area of the centre opening 3 or a corresponding opening. This arrangement prevents the growth of the pressure of the smoke gases in the turbulence chamber to become unreasonably great. The smoke gases being exhausted in turbulence motion through the .centre opening 3 form to the axis A-A a lowpressure field that absorbs additional air through the air channel 2.

In the embodiment of Fig. 1 the centre opening 3 has been formed to intermediate chamber 31 that comprises a right cylindrical space. In this way the generation of a sufficiently strong axial lowpressure field by means of advancing gas turbulence immediately after the turbulence chamber is ascertained and an efficient supply of additional air is guaranteed.

It is preferable to arrange a ring-shaped edge 32 to the connecting point of the second wall 11 of the turbulence chamber 1 and of the centre opening 3 and at the same time of the intermediate chamber 31. This can be formed, for example, of the extension part of the intermediate chamber 31. The edge 32 disconnects the direct contact between the walls of the chambers 1 and 31. So the escape of the smoke gases from the turbulence chamber 1 is prevented before the chamber has been filled with gas and a strong turbulence current has been formed there.

The exhaust chamber 4 is a cylinder-symmetrical space that is bounded to conical walls, outer wall 41 and inner wall 42. It has been connected with a ring-shaped channel 5 or opening to the actual combustion chamber 6. The opening angle β of the conical outer wall 41 of the turbulence chamber is between 75°...30°, preferably 45°. The opening angled of the inner wall, which is half of the point angle of the cone, is either as big as the opening angle 15 of the outer wall or a little bigger, e.g. 5°...15°. Then the effective cross-area of the turbulence chamber 4 reduces towards the reaction chamber 6. The cross-area of the

IjϋREAl_/

_O PI

I WIPO centre opening 3 and the intermediate chamber 31 is as big or bigger than the cross-area of the outlet opening 5 of the turbulence chamber.

When the opening angle β of the outer wall 41 of the exhaust chamber is of the size as shown afore, the gas turbulence widenes and advances in a controlled way from the intermediate chamber 4 to the combustion chamber 6. By means of the inner wall 42 the exhaust chamber 4 is restricted in a way that the burning gas turbulence is fed from a relatively narrow ring-shaped area to the combustion chamber 6. So the pressure hits backwards to the lowpressure space of the intermediate chamber, which hits on appearing would choke the whole afterburning process. E.g. the pressure hits moving back and forth caused by the motor are evenly divided by means of the exhaust chamber.

The actual combustion chamber 6 is a cylindrical space the axis of which is combined to the main axis A-A of the afterburner. The exhaust chamber 4 is connected to the combustion chamber with a ring-shaped outlet opening or channel 5. The combustion chamber has been connected further to the exhaust or to the corresponding outlet channel. The length of the combustion chamber is preferably the same as the turbulence-, intermediate and exhaust chambers altogether.

The inlet channel 7 of smoke gases can be didived into two parts 71, 72. Through the first one 71 part of the gas is led to the turbulence chamber 1 and through the second one, favourably 10-20%, direct to the combustion chamber 6. The second part 72 is in this case formed of a spiral-shaped channel that rotates round the opening 3 and/or the intermediate chamber 31 and the exhaust chamber 4 to the outer mantle of the combustion chamber and is connected to

\S\ X EA I MPΓ the combustion chamber 6 tangentially at the same time activating the turbulence motion of burning smoke gases. This arrangement is favourable when there are plenty of smoke gases and it is not desirable or possible to connect two additional afterburning apparatuses parallelly. It is also possible to supply the second inlet channel 72 with a valve which is controlled with a suitable operating device

The second air channel 14 can be connected to the point part of the conical inner wall 42 of the exhaust chamber

4. This air channel is equipped with a conical shelter 15. A ring-shaped air channel in the vicinity of the inner wal 42 leads to the exhaust chamber 4. The inner wall 42 can also be replaced by a right conical surface as can be seen in Fig. 3.

An afterburner for smoke gases according to the invention works in the principle as follows. The smoke gases are led along the inlet channel tangentially to the turbulence chamber 1. Influenced by the inlet pressure they begin to rotate a spiral-shaped circle D with accelerating speed towards the centre of the turbulence chamber. The edge 32 prevents the gas turbulence from escaping influenced by potential axial motion component along the wall 11 from th turbulence chamber 1 before the chamber has been filled with gas and its pressure is higher than the pressure from the open air. When a sufficiently strong gas turbulence ha formed to the turbulence chamber, it begins to burst through the centre opening 3 to the intermediate chamber 31. The turbulence is concentrated in the vicinity of the mantle of the intermediate chamber, when a lowpressure field in direction of the axis A-A is formed in the middle of the turbulence.

OMPI ^" - Influenced through the pressure, difference between the outer air pressure or a pressure of a corresponding air or oxygen container and the mentioned lowpressure field air absorbs through the air tube 2 to the centre of the turbulence axially advancing in the vicinity of the mantle of the intermediate chamber and is effectively mixed with the turbulence. The temperature of the smoke gas turbulence is most often sufficiently high in order to bring forth a selfignation, when on bursting of the gas turbulence widening to the exhaust chamber 4, it at the same time ignites. The gas turbulence advancing along the outer wall 41 in the exhaust chamber further absorbs air from the second air channel 14, it widenes and is led through the exhaust chamber 4 and the outlet channel 5 to the combustion chamber 6, where the final burning takes place. The deposits remove through the exhaust tube or- the corresponding outlet channel out.

The afterburning apparatus according to the invention especially suits to remove the carbon monoxide from the smoke gases. The following reactions are known:

1. Normal oxidizing of carbon monoxide; 2C0 + 0₂ →-2C0₂

2. Water gas reaction

CO + H₂0 — C0₂ + H₂

3. The reacting of the carbon monoxide molecyles with each other, when among other things the metallic iron functions as catalyst; 2C0 —3 C0₂ + C.

The circumstances especially the temperature in the apparatus for afterburning from the centre opening 3

_OMPI_ onwards are such that one or more aforementioned reactions take place. It has to be noted that the smoke gases advance through the chamber 1, 3, 31 and 4 at the vicinity of their walls as quickly rotating gas turbulence, to which air absorbs from the air channels. The axial speed of the gas turbulence is not great. So the smoke gases remain in then afterburning apparatus relatively long and the carbon monoxide has time to disappear according to the afore¬ mentioned reactions in optimal circumstances almost perfectly. The exhaust chambers are preferably manufactured of steel, when they can also operate catal ytical1 y ( reaction 3 ) .

Fig. 3 shows a second embodiment of the apparatus for afterburning smoke gases according to the invention. The apparatus is mainly as presented above and the same reference numbers have been used for the corresponding members. To the inlet channel 8 of the smoke gases it has been arranged a ring-shaped channel 9 to which a steering cone 13 and steering baffles or plates 12 at angle to the advancing direction of the gas or to the axis A-A have been placed, the construction of which baffles is cleared in Fig. 4. The baffles 12 change the axial motion of the smoke gas advancing in the inlet pipe mainly to a tangential rotating motion when the gas is bursting to the turbulence chamber 1. In connection to the centre opening 3 that has not been formed to an intermediate chamber, there has been arranged an electrical spark ignitor 16 for ascertainment of gas ignition. Plate-shaped organs 18 that form pressure pockets and in this way damp pressure waves, have been placed to the exhaust pipe 17 and the air channel 2.

Fig. 5 shows the third embodiment of the invention. The reference numbers are mostly the same as above. In this apparatus for afterburning the inlet channel 8 of the smoke

_PMPI gases has been divided into two parts 81, 82 in direction of the main axis A-A. Through the first channel 81 steered by the baffles 12 part of the gas is led in rotation movement to the turbulence chamber 1 and through the second channel 82 direct to the combustion chamber 6. The second channel additionally consists of at least two ring-shaped longish parts 82a, 82b and 82c lying inside the other. The intermediate chamber 31 , the exhaust chamber 4 and the combustion chamber 5 is so preheated .with the incoming smoke gas and also heatinsulated from the environment.

The second wall 11 of the turbulence chamber 1 is divided into stairs 11a, 11b and 11c. By means of these also the turbulence chamber is divided into three areas that have been marked with broken lines in Fig. 5. The gas turbulences are formed in the turbulence chamber one stair area at a time and the turbulence chamber is evenly filled from the periphery to the centre.

In order to proceed with' the removing of the injurious gases of the smoke gases, particularly carbon monoxide and light carbon hydrogens, known catalysts can be used as coating or as changeable charge in the combustion chamber. It is especially preferable to use the catalytical coatings in the intermediate 31 and exhaust chamber 4 where the hot gas turbulence particularly wipes the outer surfaces of the said chambers like the outer wall 41 of the exhaust chamber.

Fig. 6 also shows an embodiment of the invention where similar apparatus for afterburning as shown above are in series. Each apparatus comprises the exhaust chamber 4 placed after the turbulence chamber 1 and the centre opening 3. The ring chamber 9 leading to the turbulence chamber 1 can have either the steering baffles 12 or

OMPI vvΪP - stationary and/or rotating turbine baffles in order to generate the turbulence motion of the gas. Air can be led either through a hollow axis 19 or through the channels in the centre of the combustion space or through the nozzle 2 to the exhaust chambers. The chamber spaces 1, 4 have been placed to a distance from each other and the diameter of the first one is smaller than that of the next one etc. Th angles of ascent of the steering baffles 12 are preferably arranged in a way that the angle of ascent connected with the latter chamber is bigger than the angle of ascent connected with the former chamber.

Fig. 7 shows an embodiment of the invention where the chambers 1 , 31 , 4 and the air channel 2 have been arranged in succesion in a way that they form a symmetrical system. The inner back and forth pressure wave of the exhaust pipes generates a lowpressure and a suction in the chamber space independent of the direction of the pressure wave in the exhaust pipes.

The invention has been described above mainly for use with a combustion engine. It is, however, clear that an apparatus according to the invention can be used for burning of waste and smoke gases of any process.

Claims

1. An apparatus for afterburning of smoke gases, e.g. for exhaust gases of a combustion engine, which apparatus consists of a turbulence chamber (1), to which the gas to be additionally burnt is tangentially brought, which chamber is cylinder-symmetrical and widening from the edges towards the centre and to the axis (A-A) of which there has been connected an air channel (2) at the centre of whose wall (11) there is an opening (3) through which the mixture of gas and air removes from the turbulence chamber (1), c h a r a c t e r i z e d in that the said opening (3) has been connected to the exhaust chamber (4) that is a cylinder-symmetrical space that is confined both to the conical outer wall (41) and to the -inner wall (42) and which exhaust chamber (4) is connected with a ring-shaped channel (5) or -opening to the actual combustion chamber (6).

2. The apparatus of claim 1, c h a r a c t e r i z e d in that the said opening (3) has been formed to an inter¬ mediate chamber (31) that comprises a right cylindrical space.

3. The apparatus of claim 1 or 2 c h a r a c t e r ¬ i z e d in that to the centre opening (3) of the turbulence chamber (1) or to its immediate vicinity there has been arranged a ring-shaped edge (32) that reaches a certain distance from the outer mantle (11) of the turbulence chamber towards the inner space.

4. The apparatus of claim 3 or 4, c h a r a c t e r ¬ i z e d in that the opening angle (|3) of the conical outer wall (41) of the. exhaust chamber (4) is between 75 30 preferably 45°.

"BUREAU _OMPI

5. The apparatus of claim 3 or 4, c h a r a c t e r ¬ i z e d in that to the point part of the conical inner wall (42) another air channel (14) has been connected, thi channel being preferably equipped with a conical shelter (15).

6. The apparatus of claim 3 or 4, c h a r a c t e r ¬ i z e d in that the inlet channel (7) of the smoke gases has been divided into two parts (71, 72) and a part of the gas is led to the turbulence chamber (1) through the first one (71) and a part of the gas through the second one (72), preferably 10-20SS, direct to the combustion chamber (6).

7. The apparatus of claim 3 or 4, c h a r a c t e r - i z e d in that to the inlet channel (8) of smoke gases there has been arranged a ring-shaped channel (9) and this channel is equipped with steering baffles or -plates (^'12, 13) at an angle in regard to the axis (A-A), which baffles change the axial motion of the smoke gas advancing in the inlet pipe mainly to a tangential rotating motion when entering the turbulence chamber (1).

8. The apparatus of claim 3 or 4, c h a r a c t e r ¬ i z e d in that the cross-area of the inlet channel (7, 9) for the smoke gas is as big as the cross-area of the centre opening (3) or equivalent (31).

9. The apparatus of claim 3, 4 or 8, c h a r a c t e r ¬ i z e d in that the cross-area of the centre opening (3) or equivalent (31) is as big or bigger than the cross-area of the second ring channel (5).

10. The apparatus of any of the previous claims, c h a r a c t e r i z e d in that they have been connected at least two in series and/or parallelly.