WO2014180861A1 - Device and method for separating foreign particles out of a gas stream - Google Patents

Abstract

The invention relates to a device and method for separating foreign particles out of a gas stream. To this end the apparatus comprises the following features: a pipeline (1) having an inlet opening (2) for introduction of the gas stream to be treated; a Venturi constriction (3) in the pipeline (1); at least one injection nozzle (4) disposed before or in the Venturi constriction (3) for injection of liquid into the pipeline; a displacement body (5) which is disposed in the pipeline (1), which forms an annular gap together with the internal shell surface of the pipeline (1) and which extends in the axial direction at least over the outlet region of the Venturi constriction (3); guide vanes (6) are provided which are disposed on the displacement member (5) or in the region of the displacement member (5) on the lining of the pipeline (1); downstream of the displacement body (5) the pipeline (1) has an arrangement for discharging foreign particles out of the circumferential region of the cross-section and purified gas out of the central region of the cross-section.

Description

 Apparatus and method for separating foreign particles from a gas stream

The invention relates to the removal of dust-like, gaseous, mist-like or liquid substances from a gas stream to be purified in a device and a corresponding method.

From DE 26 56 151 A1 discloses a device for separating

Solid state contaminants from a gas stream known. DE 103 35 194 A1 shows a pre-separator for the removal of impurities from the air in an air intake system of an automotive engine. US 4 629 481 A shows a modular separation unit for separating a liquid from a gas-liquid mixture. EP 1 458 490 B1 shows a cyclone separator, with a tube and a

Inlet opening and an outflow opening, wherein in the tube, a stationary vertebral body is arranged, which sets the gas / liquid flow in a spiral movement, so that the liquid contained in the gas flow is thrown radially outward under the influence of the centrifugal force prevailing in the spiral flow and is separated there ,

Such apparatus may be needed in particular in the manufacture of wood or wood pellets. They serve to separate from

 Wood dusts and volatile organic compounds in pneumatic conveying and drying systems.

In such applications, it is known to use gas scrubbers or centrifugal separators of different types, which serve the purification of gases with and without the aid of a washing liquid. There are DC separators (as stated above) and countercurrent separator. The latter are disadvantageous because of the associated pressure losses in the pipe system. Also, the selectivity in the known prior art is not sufficient to achieve satisfactory results, especially when retrofitting in a confined space. Elaborate separator with the necessary selectivity, in turn, require a large amount of space and may be difficult in terms of plant technology planned or almost not retrofitted in existing facilities. Also, the quantity is unsatisfactory.

The invention has for its object to provide a device for separating foreign particles from a gas stream, which is simpler in construction and cheaper to manufacture, which has a higher selectivity and a generally improved efficiency. Furthermore, a procedure should be created.

The object of the device for separating foreign particles from a gas stream comprises the following features:

 - A pipeline with an inlet opening for introducing the gas stream to be treated;

 - a Venturi constriction in the pipeline;

 - At least one arranged in front of or in the venturi constriction

 Injection nozzle for injecting liquid into the pipeline;

 - A arranged in the pipeline displacement body which forms an annular gap with the inner circumferential surface of the pipe and which extends in the axial direction at least over the exit region of the Venturi constriction;

 - There are provided guide vanes, which are arranged on the displacement body or in the region of the displacement body to the soffit of the pipe;

- The pipeline has downstream of the displacement body means for removing foreign particles from the peripheral region of their

 Cross-section, as well as purified gas from the central region of its cross-section.

The solution for the method for separating foreign particles from a

Gas stream, comprising the following process steps: introduction of a

Foreign particles laden gas stream into a pipeline, which has a Venturi constriction to increase the velocity of the gas stream,

Injecting liquid into the gas stream by means of injection nozzles prior to or during the passage of the Venturi constriction, further increasing the velocity of the gas stream by means of a cross-section reducing coaxial displacer within the conduit, creating a rotational flow of gas flow around the conduit axial extension of the pipeline by means of vanes for attachment of the

Foreign particles and the liquid near the soffit of the pipeline and

Separation of the liquid with the foreign particles than at the soffit of the

Pipeline adjacent partial flow of located in the central region of the cross-section gas flow.

Advantageously, the power increase and the small installation space is achieved by the combination of the above features. Thereby the acceleration of a

Gas flow through a cross-sectional constriction with simultaneous spraying of the washing liquid increases the cleaning performance. The occurring high

 Shearing forces between the gas stream and the liquid lead to the formation of very fine drops of liquid to which disperse solid particles adhere or which coagulate with foreign liquid drops. In addition, water-soluble gaseous

Components are absorbed on the surface of the drops. The washing performance correlates with the specific surface of the droplets and is thus the

 Diameter of the drops inversely proportional. The laden after washing laundry liquid drops are due to their inertia by the integrated axial DC swirl deposition in the downstream

Droplet separator immediately separated from the gas stream.

The basic idea is essentially to be able to perform all the necessary functions for the efficient separation of foreign particles from a gas stream in a single apparatus. This device is characterized by low structural complexity and applicability in existing pipe systems.

The advantages of the device according to the invention can therefore be as follows

sum up:

Compact design for integration into an existing pipeline.

 It can thus be inventive devices in an existing

 Install pipeline.

- Depending on space, the device according to the invention can be arranged vertically or horizontally or inclined. Simultaneous acceleration and swirl generation in an annular gap improves the washing performance.

 The adjustable free flow area in the nozzle allows adjustment during operation.

 - In view of the DC principle of the cyclone part of the device, the pressure loss in the pipeline is low.

 There is no need for a droplet separator cyclone as a separate component.

The device is suitable for the separation of

- Noxious gases, for example VOC, HCl, SO ₂ , Cl ₂ , NH ₃ , HBR.

Acid mists, for example HCl, H ₂ S0 ₄ , H ₃ P0 ₄ or oil mists.

 Fine dust particles, for example metals, metal oxides, color pigments, fly ash, carbon black, wood, salts. Such a device thus combines the function of gas scrubbing by injection of liquid, in particular water, and their atomization and the subsequent swirl generation. The separation of the foreign particles proceeds according to the combined principle of a Venturi scrubber with a DC cyclone. It is preferably provided that the guide vanes are arranged between the inflow end and the outflow end of the displacement body.

In combination or as a single feature can

 - have the wall of the pipeline downstream of the displacement body one or more branch lines for foreign particles;

 - the pipeline at or downstream of the foreign particle openings has a constriction;

 - The bottleneck an outlet opening to the outlet of the purified gas

 be downstream;

 - For discharging the purified gas stream downstream of the

 Displacement body be provided a dip tube, the inlet opening of the pipeline is concentrically enclosed and receives the gas stream;

for discharging the foreign particles downstream of the inlet opening of the

Immersion tube may be provided one or more branch lines; - Be the displacer axially displaceable;

 - The displacement body in the set axial position be stationary;

 - The displacement body rotationally fixed but axially displaceable. In a variant which is necessary depending on the installation situation, the pipeline can run vertically in the area of the displacement body and the displacement body can float freely in the gas flow without mechanical holding devices.

Preferably, the upstream end of the displacer may be in the shape of a cone having a tip directed against the flow, and / or the outflow end of the displacer may be in the shape of a cone with a downstream tip.

The device is suitable for carrying out the method, but can also be operated independently.

The invention is explained in more detail with reference to the drawing. The following is shown in detail: FIG. 1 shows a first embodiment of a device according to the invention.

FIG. 2 shows a section of the object of FIG.

Constriction and the repressive body regarding.

FIG. 3 shows a schematic representation of an alternative solution of the invention

 End region of the device of Figure 1.

The device according to the invention shown in FIG. 1 comprises a pipeline 1 with an inlet opening 2 for introducing the gas stream to be treated. The

Flow direction of the gas stream is denoted by 1 1. The pipeline 1 has a venturi constriction 3. In the flow direction 1 1 seen in front of the venturi constriction 3 is an injection device comprising a plurality of injection nozzles 4 for injecting liquid into the pipeline 1. In the present case, it is preferably water. The pipeline 1 encloses a displacement body 5. This is arranged concentrically in the pipeline 1. The upstream end 12 of the displacement body 5 has the shape of a cone with directed against the flow tip. The outflow end 13 of the displacement body 5 also has the shape of a cone with in

Outflow pointing tip.

The displacement body 5 forms with the lateral surface of the pipe 1 a

Annular gap. He is also equipped with vanes 6. These are distributed over the entire circumference of the displacement body 5 in a uniform arrangement. See also Figure 2.

In an axial section downstream of the displacement body 5 is a constriction 7. The pipe 1 is abruptly reduced at this constriction to a smaller diameter. Accordingly, the pipeline 1 is less

Diameter continues. In this case, the inlet 14 of the pipe 1 with the smaller diameter by a certain distance upstream in the previous section with a larger diameter of the pipe 1 protrude (immersion principle). At the constriction 7, a partial flow 15 is branched off, while the branch line 8 is tangentially connected to the larger diameter portion of pipe 1, see. Figure 1, sectional view right.

Alternatively to the design of Figure 1 of the end portion of a device according to the invention, the end portion can also be designed as shown in Figure 3. As you can see, the pipe 1 runs vertically. It protrudes a dip tube 9 into the pipe 1 in this case. The inlet opening 10 of the dip tube 9 is surrounded concentrically by pipeline 1. Incidentally, the branched partial flow 15 preferably consists of contaminated liquid.

The device described works as follows:

A laden with foreign particles air flow enters through the inlet opening 2 of the pipe 1. The air flow then passes to the collar of injectors 4. These may be located just before or within the venturi throat 3. The occurring high shear forces between air and liquid lead to a Formation of extremely fine drops of liquid. The foreign substances are deposited on these. Through the annular gap between the displacement body 5 and the inner circumferential surface of the pipe 1, a strong acceleration is generated. The displacement body 5 with its guide vanes 6 acts as a swirl generator, which additionally increases the flow velocity and thus also the shear forces between air and particle-laden liquid droplets. The liquid droplets are interposed in the shear field

Displacement body 5 and wall of the pipe 1 further torn. This increases the specific surface area and increases the absorption capacity. In the annular gap of the free cross-section between the liquid on the one hand and disperse or gaseous contamination on the other hand is reduced. This will be the

 Contact frequency between foreign particles and air to be cleaned increased. In addition, due to the inertia of the disperse phase one for mixing

Gas mixture and foreign particles or drops forced in the region of the displacement body. All effects described have a positive effect on the washing performance.

The vanes 6 are arranged in the illustrated embodiment, the displacement body 5. Instead, they can also be fixed to the soffit of the pipe 1. The subsequent deposition of the loaded washing liquid drops from the rotating air flow takes place on the principle of a DC cyclone. In this case, flow and outflow run without internal reversal of direction. See the figure 3. The displacement body 5 may, preferably with an adjusting device 16, be axially displaceable. Once set in a specific axial position, it is initially stationary. Thus, the flow cross section at the injection point of the water can be adjusted according to the requirements of the operation. However, the following embodiment is also conceivable: The pipeline 1 extends vertically in the region of the displacement body 5. The displacement body does not necessarily have to be fixed, for example by mechanical connections to the fixed environment. Rather, it can move freely in the flow, preferably only in the axial direction, thus up and down. Incidentally, he is exactly the same as he was before It performs its functions just as well as the stationary displacement body: it thus forms an annular gap together with the inner surface of the wall of the pipe 1; He also creates a spin. Its weight can be sized as it meets the requirements of the practice. In this case, however, a guide device is provided, so that the displacement body is indeed axially movable in the pipeline 1 and at the same time can provide for the rotational movement of the gas stream. This can by a corresponding geometric arrangement (not shown), for example by a groove in the displacement body, in which a guide plate or a spring, connected to the reveal of the pipe 1, engages. In such an arrangement, the displacement body may also function as a kind of check valve or

Take over the closing unit in the absence of the gas flow for the pipeline 1. 1455

List of Reference Numerals: P1455

1 pipeline

 2 inlet opening

 3 Venturi constriction

4 injector

 5 displacement body

6 vane

 7 bottleneck

 8 branch line

 9 dip tube

 10 inlet opening

 1 1 flow direction

12 approaches

 13 outflow ends

 14 inlet

 15 partial flow

 16 adjustment device

Claims

claims Device for separating foreign particles from a gas stream, comprising the following features:  a pipeline (1) having an inlet opening (2) for introducing the gas stream to be treated;  a Venturi constriction (3) in the pipeline (1);  at least one injection nozzle (4) disposed in front of or in the venturi throat (3) for injecting liquid into the pipeline;  a displacement body (5) arranged in the pipeline (1), which forms an annular gap with the inner lateral surface of the pipeline (1) and which extends in the axial direction at least over the exit area of the venturi throat (3);  there are provided vanes (6) which are arranged on the displacement body (5) or in the region of the displacement body (5) on the soffit of the pipe (1);  the pipeline (1) has downstream of the displacement body (5) a device for removing foreign particles from the peripheral region of its cross-section, as well as purified gas from the central region of its cross-section. Apparatus according to claim 3, characterized in that the guide vanes (6) are located between the upstream end (12) and the downstream end (13) of the displacer (5). Device according to one of claims 1 or 2, characterized d u r c h the following features:  the wall of the pipeline (1) faces downstream of the  Displacement body one or more outlet openings for  Foreign particles on;  the pipeline at or downstream of the openings points for  Foreign particles have a bottleneck (7); the constriction (7) is followed by an outlet opening to the outlet of the purified gas. Device according to one of claims 1 or 2, characterized by the following features:  for discharging the purified gas stream is downstream of the  Displacement body (5) a dip tube (9) provided, whose  Inlet opening (10) of the pipe (1) is concentrically enclosed and receives the gas stream;  for discharging the foreign particles, one or more branch lines (8) are provided downstream of the inlet opening (10) of the dip tube (9). Device according to one of claims 1 to 4, d a d u r c h gekennzeich net, that the displacement body (5) is axially displaceable and / or stationary in the set axial position. Displacement body according to one of claims 1 to 4, characterized in that the pipeline (1) in the region of Displacement body (5) extends vertically, and that the displacement body (5) floats in the gas stream without mechanical holding devices, preferably with a rotation lock. Device according to one of claims 1 to 6, characterized in that the upstream end (12) of the displacement body (5) has the shape of a cone with directed against the flow tip. Device according to one of claims 1 to 7, d a d u r c h gekennzeich net that the outflow end (13) of the displacement body (5) has the shape of a cone with downstream tip. Method for separating foreign particles from a gas stream, comprising the following method steps:  Introducing a gas stream laden with foreign particles into a pipeline (1) which has a Venturi constriction 3 for increasing the velocity of the gas stream, Injecting liquid into the gas stream by means of injection nozzles before or during the flow through the Venturi constriction 3, further increasing the velocity of the gas stream by means of a cross-section reducing coaxial displacement body (5) within the pipeline (1), Generating a rotational flow of the gas stream around the axial extent of the pipeline by means of guide vanes (6) for attaching the foreign particles and the liquid in the vicinity of the soffit of the pipeline (1) and Separation of the liquid with the foreign particles as adjacent to the soffit of the pipe 1 partial stream (15) from the gas stream located in the central region of the cross section.