WO2015090333A1

WO2015090333A1 - Apparatus for cooling kiln exhaust gas in a kiln by-pass

Info

Publication number: WO2015090333A1
Application number: PCT/DK2014/050437
Authority: WO
Inventors: Karl Emil Andreas STRÖMBERG
Original assignee: FLSmidth AS
Current assignee: FLSmidth AS
Priority date: 2013-12-20
Filing date: 2014-12-17
Publication date: 2015-06-25
Anticipated expiration: 2016-06-20

Abstract

An apparatus for cooling an exhaust gas in a kiln by-pass, said apparatus comprising a quenching housing (5) comprising an inner wall (11), such as an inner tubular wall, with an inner surface (12) and an outer surface (13) and an inlet end (14) and an opposite outlet end (15). The inlet end (14) is arranged for receiving a flow of the kiln exhaust gas through an exhaust gas inlet (16). The inlet end (14) of the inner wall (11) is further provided with a cooling gas inlet (17) communicating with a cooling gas supply flow path (18) for a cooling gas and opening into a cooling and mixing chamber (19) defined by the inner wall (11). The cooling gas inlet (17) of the inner wall (11) is positioned adjacent to the inner surface (12) of the inner wall (11) and oriented to supply cooling gas to the cooling and mixing chamber (19) cocurrent with the exhaust gas (EG) and form a cooling gas flow zone (28) along the inner surface (12) of the inner wall (11) defining the cooling and mixing chamber (19).

Description

APPARATUS FOR COOLING KILN EXHAUST GAS IN A KILN BY-PASS Technical Field The present invention relates to an apparatus for cooling an exhaust gas in a kiln by-pass of a plant for manufacturing cement and a method for cooling an exhaust gas in a kiln bypass of an apparatus comprising a quenching housing.

Background

During manufacturing of cement, different types and compositions of volatile components, such as chloride, alkali and sulphur, will often be introduced together with the cement raw materials and the fuel. These volatile components will circulate in the kiln system of the plant between the burning zone, in which they undergo evaporation, and the preheater zone, in which they undergo condensation, and may cause clogging and unsteady kiln operation. One of the most common chloride compounds circulating in the kiln system is KCI.

Cement manufacturing plants may therefore be provided with a by-pass located at the riser duct or after the button cyclone of a preheater of the plant when seen in the direction of flow of the exhaust gases from the kiln.

Known plants using a by-pass duct, which is located at the riser duct or after the bottom cyclone viewed in the direction of flow of the gases, divert a portion of the exhaust gases, typically up to 10 per cent of the exhaust gases, thereby ensuring continuous extraction of volatile components from the cement manufacturing plant. In the known plants, the exhaust gases are extracted via an opening in the wall of an outlet duct into the by-pass duct. Then, the extracted exhaust gases are typically cooled in an apparatus comprising a quenching housing with a chamber by the application of air and/or water to a temperature which is lower than the condensation temperature of the volatile components, thereby allowing the volatile components to be separated in solid form from the exhaust gases for subsequent disposal or application in the finished cement or for other purposes.

WO 2009/086981 A1 by FLSmidth discloses an apparatus arranged in a kiln by-pass and comprising a quenching housing with a cooling and mixing chamber in which exhaust gases are cooled by means of air supplied to the chamber.

EP 0 927 707 B1 by Taihaiyo Cement Corporation discloses an apparatus arranged in a kiln by-pass and comprising a cooling housing having a double-tubed structure including an inner and an outer tube. Exhaust gasses flow into the inner tube and cooling gas is supplied to a flow path defined between the inner tube and the outer tube. The cooling gas is guided so as to flow into an inner area in front of the forward end portion of the inner tube against the hot exhaust gasses entering the inner tube. Thereby, the cooling gas cools the outer surface of the tube coming from the riser duct and creates a zone where a phase change of the volatile components from gas to liquid can take place and sticky substances be deposited and cause clogging and unsteady operation.

Summary of the invention

It is an object of the present invention to provide an improved apparatus for cooling kiln exhaust gases in a kiln by-pass.

The present invention relates to an apparatus for cooling an exhaust gas in a kiln by-pass, said apparatus comprising a quenching housing comprising an inner wall, such as an inner tubular wall, with an inner surface and an outer surface and an inlet end and an opposite outlet end, the inlet end being arranged for receiving a flow of the kiln exhaust gas through an exhaust gas inlet, the inlet end of the inner wall being further provided with a cooling gas inlet communicating with a cooling gas supply flow path for a cooling gas and opening into a cooling and mixing chamber defined by the inner wall, the cooling gas inlet of the inner wall being positioned adjacent to the inner surface of the inner wall and oriented to supply cooling gas to the cooling and mixing chamber cocurrent with the exhaust gas and form a cooling gas flow zone along the inner surface of the inner wall defining the cooling and mixing chamber, wherein the inner wall tapers from the inlet end towards the outlet end.

Deposition of sticky substances on the inner surface of the inner wall is avoided as the cooling gas enters the cooling and mixing chamber cocurrent with the exhaust gases and encloses the latter by forming a cooling gas flow zone along the inner surface of the inner housing, said cooling gas flow zone enclosing the flow of exhaust gasses and thereby protecting the inner chamber walls from condensation of sticky substances by the creation of a boundary layer of colder gas along the inner walls, while still providing a fast mixing and cooling of the exhaust gases. Further, the cocurrent general flow direction of the cooling gases and the exhaust gases into the mixing and cooling chamber prevents cooling of the wall of the hot riser duct by a counter-current cooling gas flow against said wall and thereby the formation of sticky substances thereon.

The general flow direction of the exhaust gas is from the exhaust gas inlet towards the outlet of the inner wall independent of whether the flow is a whirling or rotating flow or a rectilinear flow.

The general flow direction of the cooling gas is from the cooling gas inlet towards the outlet of the inner wall independent of whether the flow is a whirling or rotating flow or a rectilinear flow.

By cocurrent is to be understood that the general flow direction of the cooling gas and the exhaust gas into the cooling and mixing chamber is in the same general flow direction, i.e. from the inlet end towards the outlet end of the inner wall independent of whether one or both flows are rotating or whirling flows or rectilinear flows or a mixture thereof.

In other words, by cocurrent is to be understood that the cooling gas does not enter the cooling and mixing chamber with a flow direction counter to or perpendicular to the flow direction of the exhaust gas into the cooling and mixing chamber.

In an embodiment of the invention, the cooling gas supply flow path is formed by a ring- shaped chamber arranged at the inlet end of the inner wall and having an inner ring chamber wall forming the exhaust gas inlet or a portion thereof, said ring-shaped chamber further forming the cooling gas inlet or at least a portion thereof.

The ring-shaped chamber may be provided with a tangentially arranged cooling gas supply inlet so as to induce a whirling or rotating motion to the gas.

Thereby, an optimal cooling effect of the cooling gas is obtained as the cooling gas will stay in the cooling and mixing chamber for a longer period of time than by a linear flow, whereby the length of the quenching housing may be decreased. Additionally, an improved mixing of the cooling gas and the exhaust gases is obtained. The inner wall of the quenching housing may be cooled, such as by means of cooling means arranged on the outer surface of the inner wall or in the inner wall. The cooling means can be a cooling coil for a cooling medium.

In an embodiment of the invention, the cooling gas supply flow path is formed between an inner surface of an outer wall of the quenching housing, such as a tubular wall, arranged around the inner wall and the outer surface of the inner wall.

A cooling of the inner wall by means of the cooling gas is hereby obtained. The outer wall may be cooled by means of cooling means corresponding to those mentioned above for cooling the inner wall.

The inner wall and the outer wall can be arranged essentially in parallel. In an, at present, preferred embodiment, the inner wall tapers from the inlet end towards the outlet end.

In an, at present, preferred embodiment, the inner wall tapers seen from the inlet end to the outlet end of the quenching housing.

Thereby, the changing cross-sectional area of the cooling and mixing chamber provides compensation for the change in density of the combined cooling gas and exhaust gas from the inlet end to the outlet end, the volatile components of the exhaust gas being converted into solids. Additionally, a tapering inner wall stabilizes mixing of the cooling gas and the exhaust gas.

The inner wall may be conical. By having a conical inner wall, the mixing flow is advantageously stabilized. In a preferred embodiment, the quenching housing comprises a tangentially arranged cooling gas inlet to the cooling gas supply flow path formed between the outer and the inner wall so as to induce a whirling or rotating motion to the cooling gas around the inner wall.

The whirling or rotating movement of the cooling gas continues through the cooling gas and into the cooling and mixing chamber. Thereby, the cooling gas whirls or rotates along the inner surface of the inner wall, i.e. provides a whirling or rotating flow of cooling gas in the cooling gas flow zone along the inner surface of the inner wall.

The outer wall may taper when seen from the inlet end to the outlet end.

The cooling gas supply flow path may be provided with whirl-inducing means, such as one or more vanes, to induce a whirling motion to the cooling gas so that it rotates along the inner surface of the inner wall tube when entering the cooling and mixing chamber.

The whirl-inducing means may be used both for inducing a whirling or rotating motion and/or control and stabilize such motion. The cooling gas inlet can be formed as a ring-shaped slot surrounding the exhaust gas inlet.

According to an embodiment of the invention, the quenching housing is extended at the inlet end of the inner wall by means of an extension tube of refractory, said tube having a distal end being adapted to extend into an exhaust gas duct of a kiln plant and a proximal end optionally forming the exhaust gas inlet or at least a part of the exhaust gas inlet.

In general, the flowing speed of the cooling gas can be lower than the flowing speed of the exhaust gases, such as from half the speed of the exhaust gases to slightly below the speed thereof.

The cooling gas can be any gas. However, at present, atmospheric air or atmospheric air mixed with water is preferred. The present invention further relates to a method for cooling an exhaust gas in a kiln bypass in a quenching housing having an inner wall such as a tubular wall with an inner surface and defining a cooling and mixing chamber, wherein a flow of kiln exhaust gas is supplied to the cooling chamber through an exhaust gas inlet arranged at an inlet end of the inner wall so as to flow towards an outlet end of the inner wall, and a cooling gas is supplied to the cooling and mixing chamber through a cooling gas inlet arranged at the inlet end of the inner chamber, the cooling gas being supplied through the cooling gas inlet in a manner by which it enters the cooling and mixing chamber adjacent to the inner surface of the inner wall and cocurrent with the exhaust entering the cooling and mixing chamber so as to flow along the inner surface of the inner wall and provide a mixing and fast cooling of the exhaust gas.

Thereby, the cooling gas surrounds the exhaust gases and forms a cooling gas flow path along the inner surface of the inner wall and prevents deposition of sticky substances on the inner wall or any other portion of the apparatus.

A whirling or rotating motion may be induced to the cooling gas entering the cooling and mixing chamber so that it flows along the inner surface of the wall. By inducing a whirling motion in the cooling gas, the cooling gas may be controlled to a relatively well-defined cooling flow zone between the inner wall and the exhaust gas with a good mixing stability between the cooling gas and the exhaust gas.

The inner wall may be cooled, such as on the outer surface thereof. Additional cooling of an outer surface of the inner wall may advantageously enhance safety by minimizing risks of overheating during abnormal flow conditions.

Brief description of the drawings

The invention is explained in further details with reference to embodiments shown in the drawings wherein

Fig. 1 diagrammatically shows a by-pass arrangement of a cement manufacturing plant comprising an apparatus according to the invention,

Fig. 2 shows a diagrammatical sectional view of a first embodiment of the invention, and Fig. 3 shows a diagrammatical sectional view of a second embodiment of the invention.

Detailed description of the Invention Fig. 1 shows a part of a cement manufacturing plant comprising a rotary kiln 1 . Exhaust gases EG leave the kiln 1 through a riser duct 2. As shown, the plant also comprises a bypass installation or kiln by-pass 10. The kiln by-pass 10 comprises an outlet duct commonly referred to as an extension tube 3 extending at one end thereof into the riser duct 2 so as to by-pass a fraction of the exhaust gas from the kiln 1 . The opposite end of the outlet duct is connected to a quenching housing 5 of the apparatus 4 according to the invention. The outlet duct can be considered as an extension of the quenching housing and therefore be considered as an extension tube 3 of the apparatus 4, said apparatus thus comprising said quenching housing and said extension tube. As will be explained later, the quenching housing 5 comprises a cooling chamber in which the exhaust gases are cooled and mixed with a cooling gas supplied to the quenching housing 5 by means of a cooling fan 6. The cooled and mixed gas is transferred to a conditioning device 7 for additionally cooling of the cooled mixed gases. From the conditioning device 7, the cooled and mixed gases are transferred to a filter 8 for separating solid matter from the gases. An exhaust fan 9 draws the gases and the solid matter through the by-pass.

Fig. 2 shows a first embodiment of an apparatus according to the invention comprising a quenching housing 5 having an inner tubular wall 1 1 with an inner surface 12 and an outer surface 13 and an inlet end 14 and an opposite outlet end 15. The inlet end 14 is arranged for receiving a flow of kiln exhaust gas EG through an exhaust gas inlet 16. The inner wall 1 1 defines a cooling and mixing chamber 19. The inlet end 14 of the inner wall is further provided with a cooling gas inlet 17.

The cooling gas inlet to the cooling and mixing chamber 19 is arranged adjacent to the inner surface 12 of the inner wall 1 1 . In the present embodiment, the cooling gas inlet is formed as a ring-shaped slot being defined by the inner surface 12 of the inner wall 1 1 at the inlet end thereof and a coaxially arranged inner ring chamber wall 21 of a ring-shaped chamber or ring chamber 20 arranged at the inlet end of the inner wall. The ring chamber 20 defines a cooling gas supply flow path 18 communicating at one end with the cooling gas inlet and with a tangentially arranged cooling gas supply inlet 22 formed in an outer cylindrical wall of the ring shaped chamber 20. The inner wall is on the outer surface 13 thereof cooled by means of cooling means 31 shown as a cooling coil.

The exhaust gas inlet 16 is arranged centrally in relation to the tubular inner wall and surrounded by the slot-shaped cooling gas inlet 17. As shown in Fig. 2, the exhaust gas inlet is defined by the inner surface of the inner ring chamber wall 21 .

The quenching housing 5 is extending by an extension tube 3 extending as previously described into a riser duct. The extension tube is made of refractory.

As indicated in Fig 2, the exhaust gas EG flows through the exhaust gas inlet 16 and into an exhaust gas flow zone 29 in the cooling and mixing chamber 19, said zone comprising essentially only exhaust gas. The tangential cooling gas supply inlet 22 induces a whirling or rotating movement to the cooling gas so that it is rotating or whirling when it flows through the slot-shaped cooling gas inlet 17 and into the cooling and mixing chamber 19. In the chamber 19, the cooling gas CG maintains its whirling or rotating motion along the inner surface 12 of the inner tubular wall 1 1 in a cooling gas flow zone 28 essentially only containing cooling gas CG. Further, it should be noted that the cooling gas CG enters the cooling and mixing chamber cocurrent with the exhaust gas EG. Between the cooling gas flow zone 28 and the exhaust gas flow zone 29, a mixed gas flow zone 30 is formed, said mixed gas flow zone 30 containing mixed cooling gas and exhaust gas. Cooled mixed gases CMG leave the cooling and mixing chamber through the outlet end thereof.

The inner tubular wall 1 1 is conically tapering when seen from the inlet end 14 towards the outlet end 15. It should be noted that the conical shape of the cooling and mixing chamber provides for a compensation of the density change of the substances in said chamber from the inlet end where only gases exist to the outlet end where the volatile substances have been converted into solids. The second embodiment of an apparatus according to the invention shown in Fig. 3 comprises a quenching housing 5 having an inner tubular wall 1 1 with an inner surface 12 and an outer surface 13 and an inlet end 14 and an opposite outlet end 15. The inlet end 14 is arranged for receiving a flow of kiln exhaust gas EG through an exhaust gas inlet 16. The inner wall 1 1 defines a cooling and mixing chamber 19. The inlet end 14 of the inner wall is further provided with a cooling gas inlet 17.

The quenching housing additionally comprises an outer tubular wall 23 having an inner surface 24. An elongated cooling gas supply flow path 26 is defined between the outer surface 13 of the inner wall 1 1 and the inner surface 24 of the outer wall. The cooling gas supply flow path 18 is at the outlet end 15 provided with a cooling gas supply inlet 32. At the opposite end, the cooling gas supply flow path 18 makes a 180 degrees U-shaped turn, as the outer wall 23 is bent 180 degrees inwardly, and the elongated cooling gas supply flow path 26 thereby defines a cooling gas inlet 17 between the inner surface 24 of the bent portion of the outer wall 23 and the inner surface 12 of the inner wall 1 1 . In order to provide a smooth flow through the 180 degrees turn the adjacent end of the inner wall 1 1 is thickened and rounded.

Whirl inducing means 27 in the form of vanes extend outwardly from the outer surface 13 of the inner wall 1 1 . The vanes induce a whirling or rotating motion to the cooling gas flowing in the cooling gas supply flow path 32.

The cooling gas inlet 17 to the cooling and mixing chamber 19 is arranged adjacent to the inner surface 12 of the inner wall 1 1 . In the present embodiment, the cooling gas inlet is formed as a ring-shaped slot being defined between the inner surface 12 of the inner wall 1 1 at the inlet end thereof and the inner surface of the U-bent end portion of the outer wall. The mentioned whirling or rotating motion of the cooling gas in the cooling gas supply flow path 32 is maintained through the cooling gas inlet and in the cooling and mixing chamber 19 along the inner surface of the inner wall as explained with reference to Fig. 2.

The exhaust gas inlet 16 is arranged centrally in relation to the tubular inner wall and is defined by the outer surface of the outer tubular wall in the U-bent portion thereof.

The quenching housing is extending by an extension tube 3 extending as previously described into a riser duct. The extension tube is made of refractory.

As described with reference to Fig. 2, the exhaust gas EG flows through the exhaust gas inlet 16 and into an exhaust gas flow path flow zone in the cooling and mixing chamber 19, said zone comprising essentially only exhaust gas. The vanes in the cooling gas supply flow path 32 induce a whirling or rotating movement to the cooling gas so that it is rotating or whirling when it flows through the slot-shaped cooling gas inlet 17 and into the cooling and mixing chamber 19. In the chamber 19, the cooling gas CG maintains its whirling or rotating motion along the inner surface 12 of the inner tubular wall 1 1 in a cooling gas flow zone essentially only containing cooling gas CG. Further, it should be noted that the cooling gas CG enters the cooling and mixing chamber cocurrent with the exhaust gas EG. Between the cooling gas flow zone and the exhaust gas flow zone, a mixed gas flow zone is formed, said zone containing mixed cooling gas and exhaust gas. Cooled mixed gases CMG leave the cooling and mixing chamber through the outlet end thereof.

The inner tubular wall 1 1 and the outer tubular wall 23 are conically tapering when seen from the inlet end 14 towards the outlet end 15 and in that the second embodiment shown in Fig. 3 is provided with a tangential cooling gas supply inlet to the cooling gas supply flow path 32. The tangential inlet 22 induces a whirling or rotating motion to the cooling gas that is maintained through the cooling gas inlet 17 to the cooling and mixing chamber and in said chamber. However, it should be noted that the conical shape of the cooling and mixing chamber provides for a compensation of the density change of the substances in said chamber from the inlet end where only gases exist to the outlet end where the volatile substances have been converted into solids.

Finally, in respect of Fig. 3, it should be noted that the exhaust gas EG flows through the exhaust gas inlet 16 and into an exhaust gas flow zone 29 in the cooling and mixing chamber 19, said zone comprising essentially only exhaust gas. The tangential cooling gas supply inlet 22 induces a whirling or rotating movement to the cooling gas so that it is rotating or whirling when it flows through the slot-shaped cooling gas inlet 17 and into the cooling and mixing chamber 19. In the chamber 19, the cooling gas CG maintains its whirling or rotating motion along the inner surface 12 of the inner tubular wall 1 1 in a cooling gas flow zone 28 essentially only containing cooling gas CG. Further, it should be noted that the cooling gas CG enters the cooling and mixing chamber cocurrent with the exhaust gas EG. Between the cooling gas flow zone 28 and the exhaust gas flow zone 29, a mixed gas flow zone 30 is formed, said mixed gas flow zone 30 containing mixed cooling gas and exhaust gas. Cooled mixed gases CMG leave the cooling and mixing chamber through the outlet end thereof. List of reference numerals

1 Kiln CG Cooling Gas

2 Riser Duct CMG

3 Outlet Duct/Extension Tube EG Exhaust Gas

4 Apparatus

5 Quenching Housing

6 Cooling Fan

7 Conditioning Device

8 Filter

9 Exhaust Fan

10 Kiln By-Pass/ By-Pass Installation

1 1 Inner Wall

12 Inner Surface

13 Outer Surface

14 Inlet End

15 Outlet End

16 Exhaust Gas Inlet

17 Cooling Gas Inlet

18 Cooling Gas Supply Flow Path

19 Cooling And Mixing Chamber

20 Ring Shaped Chamber

21 Inner Ring Chamber Wall

22 Tangential Cooling Gas Supply Inlet

23 Outer Wall

24 Inner Surface Of Outer Wall

25 Outer Surface Of Outer Wall

26 Elongated cooling Gas Supply Flow Path

27 Whirl-Inducing Means

28 Cooling Gas Flow Zone

29 Exhaust Gas Flow Zone

30 Mixed Gas Flow Zone

31 Cooling Means

32 Cooling Gas Supply Inlet

Claims

1 . An apparatus (4) for cooling an exhaust gas in a kiln by-pass (10), said apparatus (10) comprising a quenching housing (5) comprising an inner wall (1 1 ), such as an inner tubular wall, with an inner surface (12) and an outer surface (13) and an inlet end (14) and an opposite outlet end (15), the inlet end (14) being arranged for receiving a flow of the kiln exhaust gas (EG) through an exhaust gas inlet (16) , the inlet end (14) of the inner wall (1 1 ) further being provided with a cooling gas inlet (17) communicating with a cooling gas supply flow path (18) for a cooling gas and opening into a cooling and mixing chamber (19) defined by the inner wall (1 1 ), the cooling gas inlet (17) of the inner wall (1 1 ) being positioned adjacent to the inner surface (12) of the inner wall (1 1 ) and oriented to supply cooling gas (CG) to the cooling and mixing chamber (19) cocurrent with the exhaust gas (EG) and form a cooling gas flow zone (28) along the inner surface (12) of the inner wall (1 1 ) defining the cooling and mixing chamber (19), wherein the inner wall (1 1 ) tapers from the inlet end (14) towards the outlet end (15).

2. An apparatus according to claim 1 , wherein the cooling gas supply flow path (18) is formed by a ring-shaped chamber (20) arranged at the inlet end (14) of the inner wall (1 1 ) and having an inner ring chamber wall (21 ) forming the exhaust gas inlet (16) or a portion thereof, said ring-shaped chamber (20) further forming the cooling gas inlet (17) or at least a portion thereof.

3. An apparatus according to claim 1 , wherein the ring-shaped chamber (20) is provided with a tangentially arranged cooling gas supply inlet (22) so as to induce a whirling or rotating motion to the gas.

4. An apparatus according to any of the preceding claims, wherein the cooling gas supply flow path (18) is formed between an inner surface of an outer wall (23) of the quenching housing (5), such as a tubular wall, arranged around the inner wall (1 1 ) and the outer surface (13) of the inner wall (1 1 ).

5. An apparatus according to claim 4, wherein the cooling gas supply flow path (18) between the inner wall (1 1 ) and the outer wall (23) constitutes an elongated cooling gas supply flow path (26).

6. An apparatus according to claims 4 or 5, wherein the inner wall (1 1 ) and the outer wall (23) are arranged essentially in parallel.

7. An apparatus according to claims 5 or 6, wherein the inner wall (1 1 ) is conical.

8. An apparatus according to any of the claims 4-7, wherein the quenching housing (5) comprises a tangentially arranged cooling gas inlet (22) to the cooling gas supply flow path (26) formed between the outer (23) and the inner (1 1 ) wall so as to induce a whirling or rotating motion to the cooling gas (CG) around the inner wall (1 1 ).

9. An apparatus according to any of the preceding claims, wherein the outer wall (23) tapers when seen from the inlet end (14) towards the outlet end (15).

10. An apparatus according to any of the preceding claims, wherein the cooling gas supply flow path (26) is provided with whirl-inducing means (27), such as one or more vanes, to induce a whirling motion to the cooling gas (CG) so that it rotates along the inner surface (12) of the inner wall (1 1 ) when entering the cooling and mixing chamber (19).

1 1 . An apparatus according to any of the preceding claims, wherein the cooling gas inlet (17) is formed as a ring-shaped slot surrounding the exhaust gas inlet (16).

12. An apparatus according to any of the preceding claims, wherein the quenching chamber (5) is extended at the inlet end (14) of the inner wall (1 1 ) by means of an extension tube (3) of refractory, said wall having a distal end being adapted to extend into an exhaust gas duct of a kiln plant and a proximal end optionally forming the exhaust gas inlet (16) or a part of the exhaust gas inlet (16).

13. A method for cooling an exhaust gas (EG) in a kiln by-pass (10) in a quenching chamber (5) having an inner wall (1 1 ) with an inner surface (12) and defining a cooling and mixing chamber (19), wherein a flow of kiln exhaust gas (EG) is supplied to the cooling chamber through an exhaust gas inlet (16) arranged at an inlet end (14) of the inner wall (1 1 ) so as to flow towards an outlet end (15) of the inner wall (1 1 ), and a cooling gas (CG) is supplied to the cooling and mixing chamber (19) through a cooling gas inlet (17) arranged at the inlet end (14) of the inner wall (1 1 ), the cooling gas (CG) being supplied through the cooling gas inlet (17) in a manner by which it enters the cooling and mixing chamber (19) adjacent to the inner surface (12) of the inner wall (1 1 ) and cocurrent with the exhaust entering the cooling and mixing chamber (19) so as to flow along the inner surface (12) and provide a mixing and fast cooling of the exhaust gas (EG).

14. A method according to claim 13, wherein a whirling or rotating motion is induced to the cooling entering the cooling and mixing chamber (19) so that it flows along the inner surface (12) of the inner wall (1 1 ).

15. A method according to any of the claims 13-14, wherein the outer surface (13) of the inner wall (1 1 ) is cooled.