EP1183490A1

EP1183490A1 - Device for thermally treating a material

Info

Publication number: EP1183490A1
Application number: EP00920577A
Authority: EP
Inventors: Van Hiep Hoang; Herbert Pingel; Karl Johann Lampe
Original assignee: Krupp Polysius AG
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 1999-04-16
Filing date: 2000-03-24
Publication date: 2002-03-06
Also published as: MXPA01010526A; DE19917310A1; US6551100B1; AU4110300A; WO2000063629A1

Abstract

The invention relates to a device for thermally treating a material, in particular for thermally and/or chemically treating said material, comprising an ascending branch (1) of a pipe conduit, a deviation chamber (2) and at least one descending branch (3) of a pipe conduit. An impact wall (2a) is provided in the deviation chamber (2) which is configured substantially cross-wise to the direction of flow of the incoming material. Said material enters the deviation chamber via the ascending branch (1) of the pipe conduit.

Description

Device for the thermal treatment of material

The invention relates to a device for the treatment of material, in particular for the thermal and / or chemical treatment of meal-like raw material.

Devices of this type are used in particular for calcining flour-shaped cement raw material. The exhaust gas stream from a sintering stage (furnace) and the exhaust air stream from a cooling stage (tertiary air) are used together in the ascending pipeline branch of a calcining stage supplied with fuel for calcining the raw meal. Here, the gas-solid dispersion in the calcining stage is diverted from the ascending pipeline branch into a descending pipeline branch and introduced into the bottom cyclone of a cyclone preheater in order to separate the calcined raw meal from the gas stream.

In order to achieve the best possible degree of calcination in this calcination stage, the aim is to carry out an optimal mixing and swirling of the gas-raw meal-fuel dispersion in the calcination stage. Through intensive mixing and swirling of the dispersion, the burnout of the fuel and the NO _χ reduction of the calciner exhaust gases can be improved on the one hand (and at the same time the emission of unburned components reduced) and on the other hand the degree of calcination can be increased by an improved heat transfer from the fuel to the good.

Various solutions for swirling or mixing the dispersion in the calcining stage are already known in practice. For example, in the ascending obstructing or descending pipeline branch, or a swirl chamber was provided in the area of the upper deflection.

EP-B-0 497 937 discloses a calcining stage in which a swirl chamber is provided in the region of its flow deflection, in which at least some of the coarse-grained fractions are separated from the gas-solid dispersion and then flow into one of the swirl chambers upstream and / or downstream branch of the calcination stage is reintroduced.

A swirl chamber is also known from EP-A-0 526 770. In its upper area it has an opening for the tangential entry of the gas-solid dispersion and on its underside a central opening for the discharge of the swirled gas-solid dispersion. Here it is possible to branch off some of the solid in the area of the swirl chamber and to recirculate it into the ascending branch of the pipeline.

From DE-A-37 35 825 a device for calcining powdery material is also known, in which a swirl head is provided in the deflection area of an ascending or descending pipeline branch.

A double deflection is also known from practice, in which the ascending branch of the pipe opens into a separating funnel from above via a 180 ° elbow. From this funnel, the dispersion is discharged upwards via a second 180 ° elbow, which merges into the descending branch of the pipeline. A part of the coarser solid particles is in the funnel discarded below and recirculated to the ascending pipeline branch. This double redirection results in a very good degree of mixing, but also requires a higher pressure drop.

Finally, DE-A-27 51 876 shows a calcining stage which is shown very schematically in an apparently angular line. However, further structural details of the deflection zone cannot be gathered from this diagram.

The invention is therefore based on the object of optimizing a device of the type mentioned at the outset with regard to the degree of mixing and pressure loss.

This object is achieved in accordance with claim 1 in that the deflection zone is formed by a deflection chamber which has a first section which is widened compared to the cross section of the ascending branch of the branch and which extends upwards through a substantially transverse to the direction of flow of the via the ascending branch of the branch into the Deflection chamber entering material oriented baffle is limited and is followed by at least a second section that runs obliquely downwards and tapers conically to the cross section of the descending pipeline branch.

According to claim 2, the solution to this problem consists in that the deflection zone is formed by a deflection chamber which has a first section which widens conically with respect to the ascending branch of the pipeline and a second section which is essentially transverse to the direction of flow of the ascending section Pipe branch into the deflection chamber baffle oriented material is limited, the descending pipeline branch protruding into the deflection chamber in the manner of an immersion tube is guided obliquely downward out of the deflection chamber.

Further advantages and refinements of the invention are explained in more detail on the basis of the description of some exemplary embodiments and the drawing.

Show in the drawing

1 shows a schematic illustration of a device for treating material according to a first exemplary embodiment,

2 to 8 show sectional views in the region of the deflection chamber according to some variants of the first exemplary embodiment,

9 shows a schematic illustration of a device for treating material according to a second exemplary embodiment,

10 to 15 are sectional views in the region of the deflection chamber according to some variants of the second exemplary embodiment,

16 shows a schematic illustration of a device for treating material in accordance with a third exemplary embodiment.

The device for treating material shown in FIG. 1 is designed as a device for calcining material, in particular cement raw material. It essentially consists of an ascending pipeline branch 1, a deflection chamber 2 and a descending pipeline branch 3.

The material, which is, for example, cement raw meal, is preheated in an upstream preheater, of which only one cyclone 4 is shown in FIG. 1, and then via a line 11 at one or more points in the ascending pipeline branch 1 given up.

On the one hand, an exhaust gas stream 5 from a sintering stage, in particular an oven 6, and, for example, tertiary air 7 coming from a cooler 12 are introduced into the ascending pipeline branch 1. Furthermore, one or more fuel supply points 8 are provided in the area of the ascending branch 1. In addition, one or more raw meal supply points 15 can be arranged in the region of the ascending branch 1.

The material is introduced in the form of a gas raw meal fuel dispersion from the ascending branch 1 via the deflection chamber 2 and the descending branch 3 into a cyclone 9 for the purpose of separating the calcined raw meal from the gas stream. The gas stream reaches the preheater via line 10 and the calcined material reaches line 6 via line 13.

Some variants of the deflection chamber 2 according to the first exemplary embodiment shown in FIG. 1 are explained in more detail below with reference to FIGS. 2 to 8: All variants have in common that the deflection chamber 2 has a baffle wall 2a which is oriented essentially transversely to the direction of flow of the material entering the deflection chamber 2 via the ascending pipeline branch 1.

The deflection chamber 2 expediently has a first section 2b which is widened compared to the cross section of the ascending pipeline branch and an adjoining second section 2c which tapers conically to the cross section of the descending pipeline branch 3. The second section 2c is oriented obliquely downwards in the exemplary embodiments shown.

In the variant shown in FIG. 2, the ascending pipeline branch 1 opens into the deflection chamber 2 as a dip pipe, the ascending pipeline branch 1 at a distance from a lateral boundary 2d of the first section 2b, i.e. centrally, protrudes into the deflection chamber. The cross section of the ascending branch of the pipeline is usually circular. However, the cross section can also be square, in particular square.

The gas-raw meal fuel dispersion entering the deflection chamber 2 is deflected by at least 135 ° without separation of particles and is discharged over the entire circumference of the deflection chamber into the descending pipeline branch 3. As the dispersion in the first section 2b hits the baffle 2a, there is intimate mixing and swirling. The second variant according to FIG. 3 differs in particular by the ascending pipeline branch 1 projecting into the deflection chamber 2. This ascending pipeline branch is again designed as a dip tube, but is arranged eccentrically to the deflection chamber 2. In this exemplary embodiment, the immersion tube borders directly on the lateral boundary 2d of the first section 2b of the deflection chamber 2. In addition, the conically tapering second section 2b of the deflection chamber 2 is oriented much steeper downward than the second section of the exemplary embodiment according to FIG.

In the variant according to FIG. 4, the ascending pipe branch 1, which is designed as an immersion tube, is conically tapered in the region of the deflection chamber. In this way, a higher rate of entry of the gas-solid fuel dispersion into the deflection chamber 2 can be achieved.

The deflection chamber 2 according to FIG. 5 is identical to the deflection chamber according to FIG. 2. Only the ascending pipeline branch 1 opening into the deflection chamber is not designed as a dip tube in this variant.

The deflection chamber shown in FIG. 6 corresponds to the deflection chamber according to FIG. 2, only the baffle wall 2a not being flat, but rather elliptically curved. In both cases, however, the baffle extends essentially transversely to the direction of flow 14 of the material entering the deflection chamber 2 via the ascending pipe branch 1. 7 and 8 show two further variants which have an ascending pipeline branch, the deflection chamber 2 and two descending pipeline branches 3a, 3b. Devices of this type are particularly useful when the gas subsequently flows through two preheater strands arranged parallel to one another.

In the variant according to FIG. 7, the baffle wall 2a is elliptically curved and in the variant according to FIG. 8 it is flat.

When designing the deflection chamber, particular attention must be paid to the lowest possible pressure loss between the inlet and outlet. At the same time, however, the greatest possible degree of mixing between the raw meal particles, the fuel particles, the exhaust gas air and the tertiary air should be achieved. A good intermingling and thus a good mixing leads to a more complete burnout and thus to a more complete calcination of the raw meal, which can ultimately also reduce the CG emission.

In the tests on which the invention is based, the pressure loss and the degree of mixing were determined for the variants shown in FIGS. 2 to 5 and for the already known double deflection described in the introduction to the description. Two gas streams (a main gas stream and a section) were used in the investigations and the degree of mixing and the pressure loss were determined. The main gas stream contained pure N ₂ as the gas component and the second stream (strand) contained pure 0 ₂ as the gas component. Complete mixing e = 1 is given if the concentrations of N ₂ and 0 ₂ are the same at any point on a cross-sectional area.

Degree of mixing e = average (1- (abs (0 ₂ -0 ₂ average)

/ (0 ₂ max - 0 ₂ medium)))

Thus the deviation from the mean value of the 0 ₂ ~ concentration is related to the maximum possible deviation and this size is averaged over the area.

The tests were based on the following initial parameters:

first gas component = 100% N ₂ v = 18 m / s T = 1023 K

second gas component = 100% 0 ₂ v = 18 m / s

T = 1173 K

The average degree of mixing when entering the deflection chamber resulted in a value e = 0.23.

The investigations then led to the following result:

Embodiment pressure loss degree of mixing

double deflection 2.1 mbar 0.932 according to status d. technology

Variant according to Fig. 2 0.98 mbar 0.86

Variant according to Fig. 3 0.51 mbar 0.78

Variant according to Figure 4 1.75 mbar 0.927 Variant according to Figure 5 0.74 mbar 0.805 It can be seen from the test results above that the design variants according to FIGS. 2 to 5 result in a significantly lower pressure loss than the double deflection according to the prior art. In particular, the exemplary embodiment according to FIG. 4 also shows very good mixing properties.

Which variant is to be preferred depends essentially on the requirements. A lower pressure loss leads to a corresponding energy saving, while a good degree of mixing in particular contributes to a reduction in pollutants.

Compared to the double deflection, the variants of the deflection chamber described above are characterized by smaller dimensions and a smaller space requirement and ultimately also by a simpler construction. The raw meal is diverted downward by the obliquely downward-directed second section 2b of the deflection chamber, which reduces the risk of caking.

9 shows a schematic illustration of a device for treating material, in particular for calcining raw cement material, according to a second exemplary embodiment. It differs from the device according to Fig.l only by the design of the deflection chamber 2 '.

The deflection chambers 2 'of the variants according to FIGS. 10 to 15 see a first section 2'b which widens conically with respect to the ascending pipeline branch and a second section which has the baffle wall 2'a. cut 2'c. In these exemplary embodiments, the descending pipeline branch 3 is preferably designed as an immersion tube. In these variants too, the baffle wall 2'a extends essentially transversely to the flow direction 14 of the material entering the deflection chamber 2 'via the ascending pipeline branch 1.

The expanding first section 2'b is also expediently oriented vertically upwards. The descending pipeline branch 3, which projects into the deflection chamber 2 'in the manner of a dip tube, is guided out of the deflection chamber 2' at an angle downwards.

In the variant according to FIG. 10, the descending pipeline branch 3 projects approximately centrally into the second section 2 'c of the deflection chamber 2'. In contrast, the descending pipeline branch 3 in the variant shown in FIG. 11 projects eccentrically into the second section 2c of the deflection chamber 2 '.

12 shows a conically enlarged opening area 3c of the descending pipeline branch 3, in order to ensure a more reliable discharge of the dispersion from the deflection chamber 2 'and to achieve a higher rate of entry of the gas-solid dispersion into the deflection chamber 2'. The deflection chamber according to FIG. 13 essentially corresponds to the deflection chamber according to FIG. 10. Only the baffle 2'a is elliptically curved in this embodiment.

The embodiment variants shown in FIGS. 14 and 15 in turn have two descending pipeline branches 3a, 3b, which come together in the interior of the deflection chamber 2 '. are guided and have a common opening area 3c. The variant according to FIG. 14 shows a flat baffle wall 2'a, while in FIG. 15 an elliptically curved baffle wall 2'a is shown.

16 shows the diagram of a plant (similar to FIG. 1) with an additional combustion chamber 17 for precalculating the preheated raw material.

The combustion chamber 17 is equipped with one or more fuel supply points 8 and is connected to the cooler 12 via a tertiary air line 7.

The raw meal preheated in the preheater and separated in the cyclone 4 reaches part of the tertiary air line 7 leading to the combustion chamber 17 and part of the ascending pipeline branch 1 of the calcining stage. The material already largely calcined in the combustion chamber 17 enters the ascending pipeline branch 1 via a line 18. A further raw meal supply point 15 is provided in the lower region of the ascending pipeline branch 1.

Otherwise, the structure and function of the system correspond to the exemplary embodiment according to Fig.l.

In all exemplary embodiments and variants, the entire material entering via the ascending branch 1 is derived via the one or the two descending branches. There is no intermediate separation of a partial flow of material. However, the invention is in no way limited to the illustrated embodiment variants. In particular, the position of the dip tube and its shape and length can be modified.

Claims

Patent claims:

Device for the heat treatment of floury raw material, which is preheated in a preheating stage, calcined in a calcining stage, finished in a firing stage and cooled in a cooling stage, the calcining stage being a pipeline through which the exhaust gases from the firing stage flow with an ascending branch, at least one descending branch and a deflection zone arranged between them, characterized in that the deflection zone is formed by a deflection chamber (2) which has a first section (2b) which is widened compared to the cross section of the ascending pipeline branch (1) and which extends upwards through a direction essentially transverse to the direction of flow of the ascending pipeline branch (1) into the deflection chamber

(2) incoming material aligned baffle wall (2a) is limited and which is followed by at least a second section (2c), which runs obliquely downwards and tapers conically to the cross section of the descending pipeline branch (3 or 3a, 3b).

Device for the heat treatment of floury raw material, which is preheated in a preheating stage, calcined in a calcining stage, finished in a firing stage and cooled in a cooling stage, the calcining stage being a pipeline through which the exhaust gases from the firing stage flow with an ascending branch, at least one descending branch and a deflection zone arranged between them, characterized in that the deflection zone is formed by a deflection chamber (2 '), which has a first section (2'b) which widens conically relative to the ascending pipeline branch (1) and a second section (2'c) which extends into the through a direction essentially transverse to the flow direction of the ascending pipeline branch (1). The material entering the deflection chamber (2') is limited by an aligned baffle wall (2'a), the descending pipe branch (3 or 3a, 3b) which projects into the deflection chamber (2') like an immersion tube and is led out of the deflection chamber obliquely downwards.

3. Device according to claim 1 or 2, characterized in that one of the two pipeline branches (1, 3, 3a, 3b) projects as a dip tube into the deflection chamber (2, 2 ').

4. Device according to claim 1 or 2, characterized in that the baffle wall (2a, 2'a) is flat.

5. Device according to claim 1 or 2, characterized in that the baffle wall is curved.

6. Device according to claim 1, characterized in that the ascending pipeline branch (1) opens centrally into the first section (2b) of the deflection chamber (2).

7. Device according to claim 1, characterized in that the ascending pipeline branch (1) opens eccentrically into the first section (2b) of the deflection chamber (2).

8. Device according to claim 1, characterized in that the ascending pipeline branch (1) is conically tapered in the area of the deflection chamber (2).

9. Device according to claim 2, characterized in that the descending pipeline branch (3) projects centrally into the second section (2'c) of the deflection chamber (2').

10. Device according to claim 2, characterized in that the descending pipeline branch projects eccentrically into the second section (2'b) of the deflection chamber.

11. The device according to claim 2, characterized in that the conically widening first section is aligned vertically upwards.

12. The device according to claim 1 or 2, characterized in that two descending pipeline branches (3a, 3b; 3'a; 3'b) are provided and the deflection chamber

(2, 2') is designed in such a way that all of the material entering via the ascending pipeline branch (1) is diverted via the two descending pipeline branches.