JP2004516135A - Apparatus for injecting fine particles into a gas stream - Google Patents

Abstract

The invention relates to a device (14) for injecting fine particles into a gas stream (12), wherein the fine particles are supplied to the device (14) in the form of an air flow. The device (14) has an annular gap (40) through which the air stream exits into the gas stream (12). The annular gap (40) is arranged such that the velocity vector (46) of the fine particles exiting the annular gap (40) is substantially perpendicular to the velocity vector (48) of the gas stream (12). Placed in The superposition of the velocity vectors (46, 48) results in a jet flow (50), which spreads in an umbrella shape in the direction of the gas flow (12).

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for injecting fine particles into a gas stream.
[0002]
[Prior art]
It is generally known that a gas flow can be treated to eject fine particles. For example, in an electric steel plant, fine lignite (brown coal) coke is injected into an exhaust gas stream discharged from a melting furnace. Porous lignite coke particles absorb pollutants contained in the exhaust gas stream. These porous lignite coke particles are then separated in a filter plant and processed in a relatively trouble-free manner. In this case, the injection of lignite coke takes place in a gas discharge pipe, which may have a diameter of several meters. In this tube, there is a laminar gas flow up to a gas velocity of 100 km / h. Injection quantity of lignite coke, should be a natural that filter installation is relatively small so as not to overload (e.g. of the order of the exhaust gas 1000 Nm ³ per lignite coke 0.1~1kg). However, this filter installation requires that the fine lignite coke particles be distributed as uniformly as possible over the entire cross section of the tube.
Up to now, injection lances for injecting lignite coke suspended in a carrier gas from several places in a pipe are known. This injection takes place in both a co-directional flow and a lateral flow. In this context, it must first be mentioned that a relatively expensive distribution device is needed to distribute the wear air flow to the large number of lances. It should also be mentioned that it is not possible to prevent the return of injected lignite coke from forming in the laminar gas flow in the pipe. This means, among other things, that some of the gas does not contact the injected lignite coke at all.
[0003]
[Problems to be solved by the invention]
Accordingly, it is an object of the present invention to provide a simple device for injecting fine particles into a gas stream to better distribute the fine particles into the gas stream.
[0004]
[Means for Solving the Problems]
In a device according to the invention for injecting fine particles into a gas stream, the fine particles are distributed to the device in the form of an air stream as in the case of known injection lances. However, the device according to the invention comprises an annular gap through which the air stream is injected transversely to the gas stream. The annular gap is arranged such that the velocity vector of the fine particles in the air flow at the outlet from the annular gap is substantially perpendicular to the velocity vector in the gas flow, and the jets spread in an umbrella shape in the direction of the gas flow. Jets are generated by superposition of these velocity vectors. Due to the umbrella of the jet jet around the annular gap, this simple device can distribute fine particles into the gas stream considerably better than with the known jet lances.
In most cases, it is advantageous if the annular gap exhibits rotational symmetry, whereby the distribution of the fine particles is likewise substantially rotationally symmetric. However, it cannot be denied that the annular gap is designed such that the distribution of the fine particles is not rotationally symmetric, and that it may be advantageous in individual cases. For example, when the internal accessory of the gas stream needs to be protected by an angle member, the annular gap can be blocked or reduced by the angle member.
[0005]
If the flow tube defined by the gas flow is not excessively large, in most cases the central streamline of the flow tube defined by the gas flow will be centered and the total area of the flow tube at a distance from the annular gap will be reduced. It is possible to accommodate with a single annular gap that produces a covering umbrella jet. In most cases, it is advantageous if the annular gap is rotationally symmetric and its axis of symmetry is the same as the central streamline.
A preferred embodiment comprises a central injection chamber radially discharging into an annular gap surrounding the central injection chamber, a retraction means for axially drawing airflow into the injection chamber, and a radial annular gap defining the path of the axial airflow. Deflecting means.
[0006]
The deflecting means for turning the course of the axial air flow into a radial annular gap can be designed, for example, as a baffle. Such baffles are, of course, subject to significant wear. In order to reduce this wear, the retraction means for the axial drawing of the air flow into the central injection chamber may have two axially opposite inlet openings for the air flow. This splits the air flow into two approximately equally strong branch flows, which flow axially toward each other from the two opposing inlet openings, collide axially with each other in the injection chamber and form an annular gap. Deviate from each other.
With the adjustable flow of secondary gas to the air stream or to the combined air stream, the distribution of fine particles in the gas stream can be easily changed. Dispersion of the particles can be improved with this pulsating device for secondary gas replenishment.
In a preferred embodiment, the device comprises a first deflector with a first outer end and a second deflector with a second outer end, wherein the first and second deflectors are The injection chambers are formed, and their outer ends are axially opposed to each other so as to form an annular gap. The two deflectors are provided so as to present an adjustable axial space, whereby the width of the annular gap is adjusted. The two deflectors are preferably designed in a shell shape. However, these deflectors can also take the form of, for example, a hemisphere.
[0007]
In a preferred embodiment, the device comprises a distributor block that splits the air stream into two branch streams. The first tube is connected to the distributor block and constitutes a first branch flow supply line for the air flow. The first tube runs transverse to the gas flow and extends parallel to the gas flow by a first tube connection holding the first deflector. The second tube is likewise connected to the distributor block and constitutes a second branch flow supply line for the air flow. The second tube also runs transversely to the gas flow and extends parallel to the gas flow by a second tube connection holding the second deflector. The two tubes are suitably arranged parallel to each other and are connected together by adjustable spacers. An adjustable spacer can adjust the axial gap between the two deflectors, thereby changing the width of the annular gap. Angled profiles may be attached to the first and / or second tubes as wear protection.
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The pipeline 10 shown in FIG. 1 is a large-diameter cylindrical tube. The pipeline 10 is, for example, the exhaust pipe of an electric furnace in a steel factory, having a diameter of several meters. A predominantly stratified gas stream is present in this pipeline with gas velocities up to 100 km / h. The flow direction of the gas flow is indicated by arrow 12. This reference number 12 is generally used to indicate gas flow. Reference numeral 11 indicates the center line of the pipeline 10 and at the same time is the center line of the gas stream 12. The gas stream 12 surrounded by the pipeline 10 is also called a “flow tube”.
Reference numeral 14 indicates an entire apparatus for ejecting fine particles according to the present invention into a gas stream 12. The illustrated apparatus is particularly concerned with pulverized lignite (lignite) coke (with a particle size of less than 1 mm). As already mentioned in the introduction, the injection volume is relatively small (for example on the order of 0.1 to 1 kg per 1000 Nm ^{3 of} exhaust gas), whereby an excellent distribution of the ground lignite coke is achieved over the entire cross section of the pipe. Is done.
[0009]
The device 14 according to the invention is fitted radially into the pipeline 10 via a side socket 16 of the pipeline 10. Fine particles (in this case, ground lignite coke) are supplied in the form of an air stream via main connection line 18. The main connection line 18 discharges to a wear-resistant solid distributor block 20 which divides the air flow into two branch flows. In this distributor block 20, a first branch stream is introduced into a first pipe 22 running radially to the center line 11 of the pipeline 10. The second branch stream is introduced in the distributor block 20 into a second pipe 24 running parallel to the first pipe 22 to the center line 11 of the pipeline 10. The first pipe 22 has a first pipe connection 26 extending coaxially with the centerline 11 in the direction of the flow 12. The second pipe 24 has a second pipe connection 28 extending coaxially with the centerline 11 in the direction of the flow 12. The first pipe connecting part 26 holds the first shell-shaped deflector 30, and the second pipe connecting part 28 holds the second shell-shaped deflector 32. The two deflectors 30, 32 are positioned axially opposite each other so as to form an injection chamber 34 therebetween, where their outer ends 36, 38 form an annular gap 40. The annular gap 40 is rotationally symmetric and its axis of symmetry is the center line 11 of the cylindrical tube 10. The two tube connections 26, 28 form two inlet openings 42, 44 in the injection chamber 34, which are axially opposed to each other on the center line 11 and essentially have the same opening width. It has.
The two air branches flow radially from one another through the two openings 42, 44 into the injection chamber 34 and are mutually bent in the direction of the annular gap 40. The radial deflection of the two branches due to the axial impingement protects the two deflectors 30, 32, because they are not significantly exposed to wear.
[0010]
It should be noted that the velocity vector 46 of the fine particles at the outlet from the annular gap 40 is essentially perpendicular to the velocity vector 48 of the gas flow 12. Thanks to the superposition of these velocity vectors 46, 48, the jet 50 from the annular gap 40 disperses umbrellaly in the direction of the gas flow 12. In fact, after exiting the annular gap 40, the radial component of the velocity vector 49 of the fine particles gradually decreases in the transverse direction of the gas flow 12 due to friction and pressure resistance, while the fine particles are axially reduced by the gas flow 12. It is gradually accelerated in the direction. In FIG. 1, the various flow paths of the fine particles after exiting the annular gap 40 are indicated by broken lines 52. Upon exiting the annular gap 40, these channels 52 are substantially perpendicular to the direction of the flow 12, gradually bend in the direction of the flow 12, and finally become parallel to the direction of the flow 12. The difference in the flow path 52 is due, for example, to the fine particles exhibiting different exit velocities at the jet chamber 34 as a result of, for example, a different acceleration or velocity loss at the exit of the annular gap 40. In most cases, the fine particles have different shapes and sizes, and this is reflected in the shape of the channel 52 by friction and pressure resistance. Furthermore, it should be noted that when flowing around the deflectors 30 and 32, turbulence may occur, which is also reflected in the different flow paths 52. Finally, it should be noted that these different channels 52 are, of course, preferred because they act to better disperse the fine particles in the laminar gas stream 12.
[0011]
The distribution of fine particles in the laminar gas stream 12 may be affected by the width of the annular gap 40. This width can be adjusted in a very simple way by an adjustable spacer 60 between the first and second tubes. This adjustable spacer 60 can also adjust the annular gap 40 if the two outer ends 36, 38 become worn. When the two tubes 22, 24 must not be sufficiently flexible to allow the width of the annular gap 40 to be adjusted by the adjustable spacer 60, the tube connections 26, 28 may be telescopic, for example. It can be designed to be stretchable.
Further, the dispersion of the fine particles in the laminar gas stream 12 can be performed by diluting the air stream with the gas. To this end, for example, the distributor block includes two secondary gas replenishers 70 and 72 capable of adjusting the flow rate, and diluent gas is supplied to the first pipe 22 and the second pipe 24 via the secondary gas replenishers 70 and 72. Can be supplied to If the pipeline 10 is at a negative pressure, in most cases there is no need to supply compressed gas. In that case, the two flow rate adjustable secondary gas replenishers 70, 72 can be designed as flow rate adjustable atmospheric extraction lines. The charge via the flow-regulated secondary gas replenishers 70, 72 can be pulsed, so that pulsation of the outlet velocity can be achieved in the annular gap 40 in a very simple manner. It should be noted that it further improves the fine particle dispersion of the laminar stream 12. The device for pulsing the flow adjustment of the secondary gas replenishment unit consists of a throttle valve which operates electromagnetically or pneumatically with a relatively short switching time. The two adjustable secondary gas replenishers 70, 72 can be throttled synchronously or asynchronously. Asynchronous throttling will often further improve the dispersion of fine particles in the laminar gas stream 12.
With respect to the tubes 22, 24, it is noted that the tubes are advantageously protected against wear in the direction of flow by the angled irons 80, 82. The transition from tube 22 or 24 to tube connection 26 or 28 is protected by tube bladders 84,86. The tubes 84, 86 are filled with solid material and friction of the solid material against the solid material occurs in this transition region.
[Brief description of the drawings]
1 is a longitudinal section through a gas flow tube of a device according to the invention for injecting fine particles into a gas flow.

Claims (16)

An apparatus for injecting fine particles into a gas stream (12), wherein the fine particles are supplied to the apparatus in the form of an air stream,
An annular gap (40) into which an air stream flows into the gas stream (12), wherein the annular gap (40) has a velocity vector (46) of the fine particles at the outlet from the annular gap (40) which is a gas flow; An injection jet (50) is created which is arranged substantially perpendicular to the velocity vector (48) of (12) and the gas flow as a result of the superposition of these velocity vectors (46, 48). An apparatus characterized by an annular gap (40) that expands in an umbrella shape in the direction of. The device according to claim 1, wherein the annular gap (40) exhibits rotational symmetry. The gas stream (12) has a central streamline (11), and the annular gap (40) is centered on the central streamline (11) of the gas stream (12). An apparatus according to claim 2. Device according to claim 3, characterized in that the annular gap (40) is rotationally symmetric with the axis of symmetry being the same as the central streamline (11) of the gas flow (12). A central injection chamber (34) which discharges radially into said peripheral annular gap (40);
Supply means (26, 42, 28, 44) for supplying an air flow axially into said central injection chamber (34);
Apparatus according to any one of the preceding claims, characterized by deflecting means for diverting the axial airflow into the annular gap (40). Apparatus according to any one of the preceding claims, characterized by a secondary gas replenisher (70, 72) with adjustable flow to the air flow. The apparatus according to claim 6, characterized in that the secondary gas supply is pulsed. Supply means for axially supplying said air flow to said central injection chamber (34) has two axially opposed inlet openings (42, 44) for said air flow;
The air streams diverge towards the two opposing inlet openings (42, 44) and impinge axially on each other in the injection chamber (34), thereby radially displacing each other into the annular gap (40). 6. Device according to claim 5, characterized in that it is split into two divergent streams which are deflected. 9. The device according to claim 8, characterized in that a secondary gas replenisher (70, 72) with adjustable flow to each of the branch flows. 9. Apparatus according to claim 8, characterized in that the two secondary gas replenishers (70, 72) have pulsed throttling devices. A first deflector (30) with a first outer end (36);
A second deflector (32) having a second outer end (38),
The first and second deflectors (30, 32) constitute the ejection chamber (34), and the two outer ends (36, 38) are axially separated from each other so as to form an annular gap (40). The device according to claim 1, wherein the device is facing. 12. The arrangement according to claim 11, wherein the two deflectors are provided with axially adjustable spaces, whereby the width of the annular gap is adjustable. apparatus. A distributor block (20) for splitting the air stream into two branch streams;
A first pipe (22) extending transversely to said gas flow (12), wherein a first pipe connection (26) runs parallel to said gas flow (12) and said first deflector (30); And said first tube (22) is connected to said distributor block (20) and constitutes a first branch flow supply line of airflow;
A second pipe (24) extending transversely to said gas flow (12), wherein a second pipe connection (28) runs parallel to said gas flow (12) and said second deflector (32); The second pipe (24) is connected to the distributor block (20) and constitutes a supply line for a second branch flow of the air flow. Equipment. 14. The device according to claim 13, wherein the first and second tubes (22, 24) are arranged parallel to each other, and the device further comprises an adjustable spacer connecting the two parallel tubes (22, 24). An apparatus according to claim 1. Apparatus according to claim 13 or claim 14, characterized in that angled profiles are applied to the first and second pipes (22, 24) as wear protection. 16. The device according to claim 1, wherein the two deflectors are shell-shaped.