WO2002050485A1

WO2002050485A1 - Device for injecting fine-grained solid particles into a gaseous stream

Info

Publication number: WO2002050485A1
Application number: PCT/EP2001/013102
Authority: WO
Inventors: Yvon Kroemmer; Jean Lambert
Original assignee: Paul Wurth S.A.
Priority date: 2000-12-18
Filing date: 2001-11-13
Publication date: 2002-06-27
Also published as: AU2002221845A1; LU90703B1; KR20030067706A; JP2004516135A; EP1344011A1; TW507009B

Abstract

The invention relates to a device (14) for injecting fine-grained solid particles into a gaseous stream (12), whereby the fine-grained solid particles are fed to the device (14) in the form of a pneumatic supply stream. The device (14) comprises an annular gap (40), through which the pneumatic supply stream exits into the gaseous stream (12). Said annular gap (40) is positioned in the gaseous stream (12) in such a way that the speed vectors (46) of the solid particles exiting the annular gap (40) are essentially perpendicular to the speed vectors (48) in the gaseous stream (12). The superposition of said speed vectors (46, 48) results in an injection stream (50), which fans out in an umbrella shape in the direction of the gaseous stream (12).

Description

DEVICE FOR INJECTING FINE-GRAINED SOLID PARTICLES INTO A GAS FLOW.

The present invention relates to a device for blowing fine-grained solid particles into a gas stream.

State of the art

It is generally known to treat a gas stream by blowing in fine-grained solid particles. For example, fine-grained brown coal coke is blown into the exhaust gas stream extracted from the melting furnace in electrical steelworks. The porous lignite coke particles adsorb pollutants contained in the exhaust gas stream. They are then separated from the exhaust gas flow in a filter system and can be disposed of relatively easily. The lignite coke is blown into a gas extraction pipeline that can have a diameter of several meters. A laminar gas flow is present in this pipeline, with gas speeds of up to 100 km / h being achieved. The quantities of brown coal coke that are blown in should of course be relatively small (in the order of magnitude, for example, 0.1-1 kg of brown coal coke per 1000 Nm ^{3 of} exhaust gas), so that the filter system is not overloaded. However, this requires the fine-grained lignite coke particles to be distributed as uniformly as possible over the entire pipe cross section.

Injection lances are known so far which blow the brown coal coke suspended in a carrier gas into the pipeline at several points, this being possible both in direct current and in cross current. It should first be noted here that a relatively complex distributor device is required to split an abrasive pneumatic delivery flow over several lances. It should also be emphasized that streaking of the injected brown coal coke in the laminar gas flow in the pipeline cannot be prevented. This means, among other things, that part of the gas does not come into contact with the blown brown coal coke at all. Object of the invention

The object of the present invention is therefore to propose a simple device for blowing fine-grained solid particles into a gas stream, which ensures a better distribution of the solid particles in the gas stream.

Characterization of the invention

In a device according to the invention for blowing fine-grained

Solid particles in a gas stream, the fine-grained solid particles of the device, as in the known blowing lances, are fed in the form of a pneumatic conveying stream. However, the device according to the invention comprises an annular gap through which the pneumatic delivery flow is blown in transversely to the gas flow. This annular gap is arranged in the gas flow in such a way that the velocity vectors of the solid particles in the pneumatic flow at the outlet from the annular gap are essentially perpendicular to the velocity vectors in the gas stream and an overlaying of these velocity vectors results in an injection jet that widens in the direction of the gas stream. Due to this umbrella-shaped widening of the injection jet around the annular gap, this simple device enables a far better distribution of the solid particles in the gas stream than the known injection lances.

In most cases, it is advantageous if the annular gap has rotational symmetry, so that the distribution of the solid particles is also essentially rotationally symmetrical. However, it cannot be ruled out that in individual cases it can be advantageous to design the annular gap in such a way that the distribution of the solid particles is not rotationally symmetrical. For example, the annular gap in an angular sector can be interrupted or reduced in order to prevent or reduce the exit of the pneumatic flow in this angular sector, e.g. because internals in the gas flow must be protected in this angular sector.

If the flow tube defined by the gas flow does not cut surface, it is usually possible to make do with a single annular gap, which is centered on the central flow line of the flow tube defined by the gas flow and generates an umbrella-shaped injection jet which covers the entire cross section of the flow tube at a certain distance from the annular gap. In most cases, it is advantageous if the annular gap has a rotational symmetry, the axis of symmetry of which is identical to the central flow line.

A preferred embodiment comprises a central injection chamber which opens radially into the annular gap surrounding it, introduction means for axially introducing the pneumatic delivery flow into the injection chamber and redirection means for redirecting the axial pneumatic delivery flow into the radial annular gap.

The diverting means for diverting the axial pneumatic flow into the radial annular gap can e.g. be designed as a baffle. However, such an impact surface is subject to severe abrasive wear. In order to reduce this abrasive wear, the introduction means for the axial introduction of the pneumatic delivery flow into the central blowing chamber can have two axially opposite inlet openings for the pneumatic delivery flow. The pneumatic flow is divided into two approximately equally strong partial flows, which flow axially from one another from the two opposite inlet openings, collide axially in the blowing chamber and thereby divert each other radially into the annular gap.

The distribution of the solid particles in the gas flow can be changed in a simple manner by means of a throttled secondary gas supply in the pneumatic feed flow or in the two pneumatic partial flows.

The scattering of the material particles can be pulsed by a device

Improve the throttling of the secondary gas supply.

In a preferred embodiment, the device comprises a first diversion body with a first outer edge and a second diversion body with a second outer edge; wherein the first and second diversion body axially opposite each other such that they form the blowing chamber and their outer edges form the annular gap. The two diversion bodies are advantageously fastened in such a way that they have an adjustable axial distance, so that the width of the annular gap can be adjusted. The two diversion bodies are preferably of shell-shaped design. However, they can also have the shape of hemispheres, for example.

In a preferred embodiment, the device comprises a distributor block for dividing the pneumatic flow into two partial flows. A first pipe is connected to the distributor block and forms a delivery line for the first partial flow of the pneumatic delivery flow. It extends transversely to the gas flow and is extended by a first pipe socket which extends parallel to the gas flow and carries the first diversion body. A second pipe is also connected to the distributor block and forms a delivery line for the second partial flow of the pneumatic delivery flow. It also extends transversely to the gas flow and is extended by a second pipe socket that extends parallel to the gas flow and carries the second diversion body. Both tubes are advantageously arranged parallel to one another and connected to one another by an adjustable spacer. The latter makes it possible to adjust the axial distance between the two diversion bodies and thus to change the width of the annular gap. An angle profile can be attached to the first and / or second pipe as protection against abrasion.

piece placement

A preferred embodiment of the invention will now be described with reference to the accompanying figure. It shows: FIG. 1: a longitudinal section through a pipeline for a gas stream, with a device according to the invention for blowing fine-grained solid particles into the gas stream. Description of a preferred embodiment of the invention with reference to the figures

The in FIG. 1 is a circular cylindrical pipe of larger diameter. It is e.g. around the gas extraction pipeline of an electric furnace from a steel mill, which can have a diameter of several meters. A predominantly laminar gas flow is present in this pipeline, with gas speeds of up to 100 km / h being achieved. The direction of flow of the gas stream is indicated by arrow 12. This reference numeral 12 is also used generally to designate the gas flow. Reference numeral 11 designates the central axis of the pipeline 10, which is also the central flow line of the gas flow 12. The gas stream 12 enclosed by the pipeline 10 is also referred to as a flow tube.

The reference numeral 14 designates a device according to the invention for blowing fine-grained solid particles into the gas stream 12. The device shown is, in particular, finely ground brown coal coke (grain size less than 1 mm). As also mentioned at the beginning, the injection quantities are relatively small (for example, 0.1-1 kg of lignite coke per 1000 Nm ^{3 of} exhaust gas), so that an excellent distribution of the powdery lignite coke must be achieved over the entire pipe cross section. The device 14 according to the invention is via a lateral tube extension

16 of the pipe 10 radially installed in the pipe 10. The fine-grained solid particles (in this case the ground lignite coke) are fed to it via a main connection line 18 in the form of a pneumatic conveying stream. This main connection line 18 opens into a massive, abrasion-resistant distributor block 20, which divides the pneumatic delivery flow into two partial flows. The first partial flow is introduced in the distribution block 20 into a first pipe 22, which extends radially to the central axis 11 of the pipe 10. The second partial flow is introduced in the distributor block 20 into a second tube 24, which is parallel to the first Pipe 22 extends to the central axis 11 of the pipeline 10. The first pipe 22 has a first pipe socket 26 which extends in the flow direction 12 coaxially to the central axis 11. The second pipe 24 has a second pipe socket 28 which extends in the flow direction 12 coaxially to the central axis 11. The first pipe socket 26 carries a first shell-shaped diverter body 30, and the second pipe socket 28 carries a second shell-shaped diverter body 32. Both diverter bodies 30, 32 lie axially opposite one another in such a way that they form an injection chamber 34, their outer edges 36, 38 being one Form annular gap 40. The latter has a rotational symmetry, the axis of symmetry of which is the central axis 11 of the circular cylindrical tube 10. The two pipe sockets 26, 28 form two inlet openings 42, 44 in the blowing chamber 34, which are axially opposite one another on the central axis 11 and have essentially the same opening width.

The two pneumatic partial flows flow radially towards one another from the two inlet openings 42, 44 of the blowing chamber 34 and in the process divert each other radially in the direction of the annular gap 40. The radial diversion due to an axial collision of the two partial flows naturally protects the two diversion bodies 30, 32, since they are exposed to much less abrasion wear. It should be noted that the velocity vectors 46 of the solid particles at the exit from the annular gap 40 are essentially perpendicular to the velocity vectors 48 in the gas stream 12. The superimposition of these speed vectors 46, 48 then results in an injection jet 50 which widens in the form of a screen in the direction of the gas stream 12 and surrounds the annular gap 40. Indeed, after exiting the annular gap 40, the radial component of the velocity vector 49 of a solid particle progressively decreases due to the friction and pressure resistance in the transverse direction of the gas stream 12; while solid particles are progressively accelerated in the axial direction by the gas stream 12. In FIG. 1, the dashed lines 52 show different flow paths of solid particles after they have left the annular gap 40. These current paths 52 are essentially perpendicular to the flow direction 12 at the exit of the annular gap 40 progressively in the direction of the flow direction 12 to finally become parallel to the flow direction 12. The differences in the flow paths 52 are caused, for example, by the fact that the solid particles at the outlet of the annular gap 40 have different outlet speeds, for example due to different accelerations or speed losses in the blowing chamber 34. The solid particles usually also have different shapes and sizes, which is also noticeable in the shape of the flow path 52 due to the friction and pressure resistance. It should also be noted that when flow flows around the diversion bodies 30, 32, turbulences also occur which are also reflected in different current paths 52. In conclusion, it should be noted that these different flow paths 52 are of course desirable because they contribute to better scattering of the solid particles in the laminar gas flow 12.

The distribution of solid particles in the laminar gas stream 12 can also be influenced by the width of the annular gap 40. This width can be set in a very simple manner by means of an adjustable spacer 60 between the first tube 22 and the second tube 24. This adjustable spacer 60 also makes it possible to adjust the annular gap 40 when the two outer edges 36, 38 wear. If the two tubes 22, 24 are not flexible enough to be able to adjust the width of the annular gap 40 via the adjustable spacer 60, e.g. the pipe socket 26, 28 can be made telescopically extendable.

The distribution of solid particles in the laminar gas stream 12 can also be carried out by diluting the pneumatic delivery stream with a gas. For this purpose, the distributor block, for example, has two throttled secondary gas feeds 70, 72, via which a diluent gas can be specifically fed into the first tube 22 or the second tube 24. If there is a negative pressure in the pipeline 10, there is usually no need to provide a pressurized gas supply. The two throttled secondary gas supplies 70, 72 can then be designed as throttled, atmospheric suction lines. It should be noted that the throughput can also be pulsed through the restrictable secondary gas supplies 70, 72, which can be done in a simple manner A pulsating exit velocity can be achieved in the annular gap 40, which further improves the scattering of the solid particles in the laminar gas stream 12. A device for pulsed throttling of the secondary gas supply can comprise, for example, an electromagnetically or pneumatically operated throttle valve with relatively short switching times. The two throttled secondary gas supplies 70, 72 can be throttled synchronously or asynchronously. Asynchronous throttling can result in a further improvement in the scattering of the solid particles in the laminar gas stream 12 in various cases. Regarding the tubes 22, 24, it should be noted that these are advantageously by means of

Angle irons 80, 82 are protected against abrasion in the direction of flow. The transition from the pipe 22 or 24 into the pipe socket 26 or 28 is protected by a pipe bag 84, 86. This pipe sack 84, 86 fills up with solids, so that friction occurs from solids to solids in this transition region.

Claims

claims

1. Device for blowing fine-grained solid particles into a gas stream (12), the fine-grained solid particles being fed to the device in the form of a pneumatic conveying stream, characterized by an annular gap (40) through which the pneumatic conveying stream exits into the gas stream (12), wherein the annular gap (40) is arranged in the gas stream (12) in such a way that the velocity vectors (46) of the solid particles at the outlet from the annular gap (40) are essentially perpendicular to the velocity vectors (48) in the gas stream (12) and are superimposed on one another this velocity vectors (46, 48) results in an injection jet (50) which widens in the form of an umbrella in the direction of the gas flow (12).

2. Device according to claim 1, characterized in that the annular gap (40) has a rotational symmetry.

3. Device according to claim 1 or 2, characterized in that the gas flow (12) has a medium flow line (11); and the annular gap (40) is centered on the medium flow line (11) of the gas flow (12).

4. The device according to claim 3, characterized in that the annular gap (40) has a rotational symmetry, the axis of symmetry with the center flow line (11) of the gas flow (12) is identical.

5. Device according to one of claims 1 to 4, characterized by a central injection chamber (34) which opens radially into the annular gap surrounding it (40);

Introduction means (26, 42, 28, 44) for axially introducing the pneumatic flow into the central injection chamber (34); and

Diverting means for diverting the axial pneumatic flow into the annular gap (40).

6. Device according to one of claims 1 to 5, characterized by a throttled secondary gas supply (70, 72) in the pneumatic flow.

7. The device according to claim 6, characterized by a device for pulsed throttling of the secondary gas supply.

8. The device according to claim 5, characterized in that the introduction means for axially introducing the pneumatic flow into the central blowing chamber (34) have two axially opposite inlet openings (42, 44) for the pneumatic flow; the pneumatic conveying flow being divided into two partial flows, which flow towards one another from the two opposite inlet openings (42, 44), axially collide in the blowing chamber (34) and thereby divert each other radially into the annular gap (40).

9. The device according to claim 8, characterized by a throttled secondary gas supply (70, 72) in each of the two partial flows.

10. The device according to claim 9, characterized by a device for pulsed throttling of the two secondary gas supplies (70, 72).

11.Device according to one of claims 1 to 10, characterized by a first diversion body (30) with a first outer edge (36); a second diverter body (32) with a second outer edge (38); the first and second diverter bodies (30, 32) being axially opposite one another in such a way that they form the blowing chamber (34) and the two outer edges (36, 38) form the annular gap (40).

12. The device according to claim 11, characterized in that the two diversion bodies (30, 32) are fastened in such a way that they have an adjustable axial distance, so that the width of the annular gap (40) is adjustable.

13. The apparatus of claim 11 or 12, characterized by: a distributor block (20) for dividing the pneumatic flow in two sub-streams; a first pipe (22) which extends transversely to the gas flow (12), with a first pipe socket (26) which extends parallel to the gas flow (12) and carries the first diversion body (30), this first pipe (22) is connected to the distributor block (20) and a delivery line for the first

Forms partial flow of the pneumatic flow; a second pipe (24) which extends transversely to the gas flow (12), with a second pipe socket (28) which extends parallel to the gas flow (12) and carries the second diversion body (32), this second pipe (24) is connected to the distributor block (20) and forms a delivery line for the second partial flow of the pneumatic delivery flow.

14. The apparatus according to claim 13, characterized in that the first and the second tube (22, 24) are arranged parallel to each other; the device further comprises an adjustable spacer (60) which connects the two parallel tubes (22, 24).

15. The device according to one of claims 13 or 14, characterized by an angle profile (80, 82) as abrasion protection on the first and / or second tube (22, 24).

16. Device according to one of claims 1 to 15, characterized in that the two diversion bodies (30, 32) are cup-shaped.