DE2163983C3 - Post-combustion system for the exhaust gases from internal combustion engines - Google Patents

Description

The invention relates to an afterburning plant for the exhaust gases from internal combustion engines, in which the exhaust gases before their afterburning a fuel-air mixture is supplied in a controlled manner in an afterburning chamber.

There are known afterburning systems of this type, in which with the help of the fuel-air mixture the afterburning is effected with an open flame. As the well-known afterburners are housed in the exhaust pipe through which the exhaust gases flow at high speed, it is quite difficult to keep the combustion of the exhaust gases stable. Furthermore, with open Flame often erratic burns such as misfire or purging, so that the exhaust afterburning disturbed and thereby the proportion of unburned parts is increased. Such is an afterburning plant known (German Patent 158), in which the fuel goes directly into the afterburning chamber is introduced and thereby entrained by a stream of compressed air. This compressed air is mixed with the fuel in the afterburning chamber, taking into account the high speed of the exhaust gases passing through this considerably hinders or even hampers a mixing process is made impossible. In another well-known case (German Ausiegeschrift 1 23S273) mündel the exhaust pipe as a collecting nozzle into the afterburning chamber, whereby shortly before the end of the nozzle the Fuel-air mixture is supplied tangentially. Here it can easily happen that the Mixture migrates as a shell around the exhaust gas flow, so that there is insufficient mixing with the exhaust gas flow is guaranteed. Finally it became known (USA.-Patent 3,131,533), the mixture feed axially in the direction of the exhaust gas flow on the outside thereof. Again, it cannot be sufficient Mixing can be guaranteed.

The object of the invention is to provide an afterburning system to create the type described above, the good mixing of exhaust gases and Air-fuel mixture guaranteed and stable combustion guaranteed.

This object is achieved by dussing the crane material-air mixture can be supplied to the afterburning chamber via a container arranged in the inlet chamber whose porous wall is provided with a plurality of projections. The feed of the mixture through a porous wall ensures optimal distribution, with the profiled training aiii the side facing the exhaust gases one strong turbulence and silky mixture is guaranteed, whereby stable moms can be achieved are.

The invention is explained in more detail below with reference to a schematic drawing; is there

Fig. I is a schematic flow diagram an afterburning system according to the invention.

F i g. 2 an explanatory view of the entire post-combustion system,

Fig. 3 is an enlarged longitudinal sectional view of a Embodiment of the Nacliverburnstabilisatois and the afterburning chamber according to FIG. 2,

F i e. 4 one of the F i g. 3 corresponding representation, which clarifies a further embodiment.

According to FIG. 1, the post-combustion system is 10 according to the invention with a delivery line 11 for the Supply of additional air into the through the Einiritlsleitung 12 incoming polluted exhaust gases provided. These exhaust gases in the correct mixing ratio are then introduced by means of a line 13 into an afterburning chamber 14 in order to burn up Burn parts completely. After the polluted exhaust gases have been post-burned, there is the post-combustion chamber 14 clean exhaust gases into the outlet line 15.

According to the main feature of the invention, the afterburning takes place in the afterburning chamber 14 stabilized by an afterburning stabilizer 16, which is described with reference to FIG. 2 to 4 in detail is discussed. The afterburning stabilizer 16 creates a premixed flame which is used as a Heat source for the afterburning of the exhaust gases acts. From a mixture metering device 17 is an additional air-fuel mixture is supplied to create and maintain the premixed flame. According to FIG. 1 is the additional air flowing in through line 18 and through the Line 19 inflowing additional fuel metered so that a correct mixture ratio is obtained and the Mixture delivery device 17 is supplied.

For the complete combustion of the exhaust gases, the temperature in the afterburning chamber 14 is increased kept at an appropriate level. This temperature control is carried out by a mixture flow

causes control device 21, which controls the intensity and thus the thermal energy generated by the premixed flame. The mixture flow control device 21 regulates the flow of the additional fuel-air mixture, which has received a correct mixture ratio, as a function of the temperature in the afterburning chamber 14. The temperature is determined by a temperature sensor TX in the afterburning chamber 14. An igniter 23 in the afterburning system 10 is used to ignite the premixed flame.

It now follows with reference to FIG. 2 a detailed description of the entire post-combustion plant 10; The post-combustion stabilizer 16 is shown as a spherical container 16a in FIG the inlet chamber 14 a of the afterburning chamber 14 housed, which is limited by a housing 14 ft will.

The exhaust gases from an internal combustion engine are fed to the inlet chamber 14 a through an inlet line 12. With the aid of an air injection device (not shown), an amount of additional air measured in a line 11 is supplied to the exhaust gases so that a lean mixture is produced. In addition, additional air is sucked in through a duct 18 ft with the aid of a fan 18 α from the surrounding atmosphere and ejected into the container 16 α of the post-combustion stabilizer. At the same time, an optimal amount of additional fuel in the atomized state is fed to the channel 18 ft with the aid of a carburetor 19 a, which is connected via a line 19 to a fuel pump (not shown).

The additional air-fuel mixture generated in this way becomes porous as it passes through the Wall 16 ft of the container 16 a mixed uniformly. This additional air-fuel mixture is ignited by a spark plug 23 a of the igniter 23. The exhaust gases hit this flame, which usually contain unburned fuel and also make-up air, so that they can be used without difficulty burn when the afterburner chamber 14 is kept at a high temperature. This burn is explained below with reference to FIG.

A temperature sensor 22 in the afterburning chamber 14 supplies a temperature-related signal which is introduced into a control device 21 which is connected to a servomotor 21 ft for actuating a throttle valve 21 c arranged in the channel 18 ft. In this way, the temperature in the afterburning chamber 14 is maintained at a level suitable for complete combustion.

Control device 21 α and drive motor of the fan 18 a are via an ignition switch 25 with a Energy source connected. The spark plug 23 a with its high voltage source 23 ft is controlled by the control device 21 α monitored.

According to FIG. 3, the post-combustion stabilizer 16 has a number of projections 16 c which are formed on the porous wall 16 ft. These projections 16c are preferably made of refractory material and act as a heat source for the combustion when the premixed flame is formed around it. These projections are heated to red heat by the pre-mixed flame. The flame forms very close to the tips of the projections 16 c.

The exhaust gases are sent into the afterburner chamber 14 at a relatively high speed. The porous wall 16 b is an obstacle that

ίο a suction and a return zone downstream Representation forms. The porous wall 16 ft also acts as a flame holder. The projections 16 c produce Small turbulence in the exhaust gas flow. With a premixed flame formed in this way anchor the combined effects of minor turbulence, suction and wake as well the return zone stable the combustion, which is shown as the hatched reaction zone.

As an unexpected desirable result, the material used in the porous wall is 16 feet does not have exceptional thermal resistance properties because of the additional air-fuel mixture is cold enough to cool the wall 16 ft. in transit. It is therefore for the porous wall 16ft for example materials such as Sintered porcelain or multilayer stainless steel mesh is suitable. Also can the projections 16 c are made of solid porcelain.

Fig. 4 shows another example of the post-combustion stabilizer 16 '. In this embodiment, an entry chamber 14'a is the afterburning chamber 14 within a porous wall 16'ft of the post-combustion stabilizer designed as a container 16 '" 16 'housed. There are a number on the inner surface of the porous wall 16'ft 16V projections provided. The container 16 ′ ″ is enclosed by a housing 14 ′ ″.

The additional air-fuel mixture is in front of the mixture delivery device 17 in the housing 147) introduced and then migrates inward through the porous wall 16'ft. This is where the mixture comes through the spark plug 32 a ignited and forms near the tips of the projections 16Y a premixed Flame. At the same time the exhaust gases are ignited by means of the line 13 by this flame, so that in the combustion chamber 14 'a reaction zone is obtained, as shown hatched. The burned ones Exhaust gases are discharged through line 15.

In the present case, small turbulences, suction and return zones do not occur to the same extent, however becomes uniform temperature distribution along with stagnant combustible gases in the Afterburning chamber 14 'received, since this is enclosed by the flames and the polluted exhaust gases be introduced into a chamber that has a relatively large volume. This leads to a reduction the amount of additional air-fuel mixture to be added. The afterburning chamber 14 'is enclosed by the porous wall 16'ft, which is cooled, so that there is no cooling problem.

For this 1 sheet of drawings

Claims (4)

Patent claims: 1. Post-combustion system for the exhaust gases from internal combustion engines, in which the exhaust gases are supplied in a controlled manner in an afterburning chamber with a fuel-air mixture, characterized in that the fuel-air mixture is supplied via an in the inlet chamber (14 a, 14 ' «) The afterburning chamber (14, 14 ') arranged container (16 a, 16'e) can be fed, the porous wall (16 b, Wb) of which is provided with a plurality of projections (16 c, 16Y). 2. Nadv, combustion system according to claim 1, characterized in that there is a throttle element (21c) in the container (16 a) with the mixture feeding line (18 h) , which via a depending on the temperature in the Nachbreniikammer ( 14) controlled Sien "motor (21 b) can be actuated. 3. Post-combustion system according to claim I or 2, characterized in that the porous wall (16 / ») is spherical in shape and the projections (16 c) are on their outside, the fuel-air mixture can be supplied from the interior ( Fig. 2 and 3). 4. After combustion system according to claim 1 or 2, characterized in that the container (16'a) forms the inlet chamber (14'a) and has the afterburning chamber in its interior, the projections (16V) on the inside of the porous wall (Iu ' b) are arranged and the fuel-air mixture can be fed to the container from its outside (P i g. 1).