WO1998046329A1

WO1998046329A1 - Filtering device for filtering solid particles out of a gaseous medium

Info

Publication number: WO1998046329A1
Application number: PCT/EP1998/002111
Authority: WO
Inventors: Jürgen BETHKE; Klaus Rabenstein; Walter Herding
Original assignee: Herding Gmbh Filtertechnik
Priority date: 1997-04-11
Filing date: 1998-04-09
Publication date: 1998-10-22
Also published as: AU7642998A; DE19715195A1; DE19880449D2

Abstract

A filtering device for filtering solid particles out of a gaseous medium has: (a) a housing (4) which contains at least one filtering element (6) whose inflow side is adjacent to an unprocessed gas chamber (20) and whose outflow side is adjacent to a purified gas chamber (18), the housing (4) being associated to a collector (8) for the filtered particles; (b) an inflow path (10) for the non-filtered medium into the unprocessed gas chamber (20); (c) and an outflow path (12) for the filtered medium out of the purified gas chamber (18). The filtering device is characterised in that (d) a duct (30) is provided in the inflow path (10) for transporting precoating material from the collector (8) or from a reservoir (22) with at least substantially the same inner pressure as the collector (8).

Description

Filter device for filtering out solid particles from a gaseous medium

The invention relates to a filter device for filtering out solid particles from a gaseous medium, comprising: (a) a housing in which at least one filter element is arranged, which adjoins a raw gas space with the inflow side and adjoins a clean gas space with the outflow side, and which is assigned a collecting container for the filtered out particles;

(b) an inflow flow path for the unfiltered medium to the raw gas space;

(c) and an outflow flow path for the filtered medium away from the clean gas space.

Such filter devices are known. If such a filter device is to be used continuously or from time to time to filter a gaseous medium which contains solid particles which are problematic for the inflow side of the at least one filter element, in particular sticky particles, very moist particles, particles which have become liquid due to increased temperature, etc. due to the nature of the particles, they adhere to the inflow side of the at least one filter element and for the most part are not properly cleaned during the next cleaning process. A considerable part of the inflow side or even the entire inflow side of the at least one filter element can be closed, as a result of which the function of the filter device is considerably impaired. At least one has to struggle with a considerable increase in the pressure difference in the filter device, which cannot be reversed by cleaning, and with a reduction in the effective filter area in the filter device. In such an environment, it has already been considered to precoate the filter elements (a term that is also common in the German professional world and which can be translated as "precoating"). In particular, a layer is made from precoating

Precoat material applied to the inflow side of the filter element in question, which, as it were, intercepts the problematic particles to be filtered out before they reach the actual inflow side of the filter element in question. When cleaning, the precoat material, along with any intercepted, filtered out, is usually removed

Particles cleaned. Before the next occurrence of problematic particles to be filtered out, it is advisable to carry out a new precoating. Particularly suitable as precoat material are solid particles which are small enough to form an effective “trapping layer”, but are not so small that they entail an excessive, additional pressure loss on the inflow side of the filter element in question.

The invention is based on the object of making available a filter device of the type mentioned at the outset, which includes an integrated, particularly simple construction and particularly unproblematic in the functional sequence of the precoat device.

To achieve this object, the filter device according to the invention is characterized in that

(d) that a line for the transport of precoat material from the

Collection container or from a storage container which is at least substantially at the same internal pressure as that

Storage tank is provided in the inflow flow path.

In the filter device according to the invention, either the content of the collecting container or the content of a storage container which is at least substantially at the same internal pressure as the Storage tank is used for the precoat material. The precoat material can either be a special material that is specifically selected for the precoat application, for example finely ground limestone. Alternatively, the particles obtained when cleaning the at least one filter element can be used as the precoat material. It is also possible to work with an intermediate option in which a mixture of special precoat particles and particles obtained during cleaning is used as the precoat material. Finally, you can also work in a variable time, for example, initially with pure, special precoat particles, which in the course of the operating time increasingly contain special precoat particles which are deposited on the upstream side of the filter element in question ) be replaced. Periodic refilling with special precoat particles or periodic refilling of special precoat particles to refresh the precoat material are further options.

In the filter device according to the invention, the precoat material is discharged from a space (collecting container or storage container) which is under a static pressure on the inside which corresponds at least substantially to the static pressure in the raw gas space of the filter device. This static pressure is generally somewhat higher than the static pressure in the inflow flow path, because there is normally a higher flow speed there than in the raw gas space. These conditions mean that the precoat material can be transported through the line into the inflow flow path in a particularly unproblematic manner. Coping with large pressure differences and correspondingly complicated shut-off devices for this are not necessary.

The storage container is preferably positioned in the collecting container. In this way, it can be used without incisive

Changes to existing or after existing ones

Integrate construction documents produced filter devices. As Another inexpensive alternative is the accommodation in a kind of lateral extension of the storage container, but moved away from the actual storage container space which is not claimed.

If the storage container is completely or partially positioned in the collecting container, it can preferably be designed to be open at the top in such a way that when the at least one filter element is cleaned, partially filtered particles get into the storage container. As has already been explained, this results in a gradual replacement of the initial contents of the storage container (normally special precoat particles) by particles which have been filtered out and originate from the raw gas to be filtered. Attention is drawn to the possibility of further refilling the storage container from time to time with special precoat particles.

According to a preferred development of the invention, the extent to which the storage container is open and / or the positioning of the storage container can be varied in order to vary the amount of particles that enter the storage container during cleaning. So you can work in particular with a variably wide-open lid of the storage container or with exchangeable, upper end plates with differently sized openings of the storage container or with a variable positioning in the further from the mentioned lateral extension of the collecting container.

Overall, one will generally proceed according to the following considerations: If the particles to be filtered out of the raw gas are reasonably well suited for precoating, it will often be unnecessary to provide a storage container and special precoat particles. If, on the other hand, good precoat properties are not guaranteed with the particles filtered out of the raw gas, or if precoating is also important at the beginning of the filter (in order to clog the inflow side of the filter element in question at the very beginning prevent), you will reach for a storage container and special precoat particles. A gradual replacement of special precoat particles by particles from cleaning will be all the more annoying (and the more need to be eliminated by periodically refreshing with special precoat particles or by moving the storage container away from the actual collecting container), the less suitable those that arise during cleaning Particles for precoating are (if only because they contain particularly problematic filtered out particles, possibly still in considerable quantities).

In many cases, however, it is particularly favorable that the storage container is positioned outside the housing and the collecting container. This position offers the particular advantages that a filter device can be retrofitted with a device for applying precoat material with minimal effort and that

Storage container for filling, changing, for maintenance work and the like is particularly conveniently accessible.

Preferably, the externally positioned storage container is connected to the raw gas space or the collecting container by a pressure compensation line, so that in this way it is at least substantially at the same internal pressure as the collecting container or the raw gas space.

To increase the efficiency of the discharge of precoat material from the collecting container or the storage container is preferably on

An injector is provided at the beginning of the line.

A bypass line is preferably located between the upper region of the collecting container or the storage container which is not filled with precoat material and the region before the beginning of the line to

Transport of precoat material provided. The bypass line ensures that at the beginning of the line there is as perfect as possible essentially the same pressure as in the collecting container or raw gas space. A flow block is preferably provided at the beginning of the line for transporting precoat material, to which a driving nozzle of the injector and one end of the bypass line are connected on the inlet side and to the outlet side the line for transporting

Precoat material is connected, and which has at least one suction opening for precoat material. In this way, all fluid lines have been clearly and compactly connected.

In a preferred development of the invention, a fluidizing plate is provided in the collecting container or in the storage container in order to loosen up the precoat material to be discharged through the line. Provision can be made to supply compressed air to the space under the fluidizing plate.

For the cleaning of the filter elements in filter devices that is required from time to time, two types of control are mainly considered, namely differential pressure-controlled and time-controlled. In the former case, the differential pressure between the raw gas space and the clean gas space decides whether a

Cleaning process is activated, in the second case the expiry of a certain time. It goes without saying that provision can be made to make the differential pressure or the time period for activating a cleaning process selectable or adjustable.

There are also two main types of control for the length of the cleaning process, namely control over the period of the cleaning process (normally an entire cleaning process includes several cleaning cycles in succession) and control over the number of cleaning cycles or

Cleaning cycles of the relevant cleaning process.

According to a preferred development, the filter device has a control device for the precoat process, with which a control device can be used (preferably after each) cleaning process can activate a precoat phase, preferably for a certain period of time. By means of this control device, the precoating can be renewed again and again after cleaning.

Alternatively, and also preferred, a control device can be provided with which precoat processes can be activated virtually independently of the cleaning processes, either discontinuously in a time-controlled manner (e.g., a new precoat process every x min, which in turn lasts for y min) or also continuously. These controls of the precoat processes are particularly suitable if the at least one filter element is cleaned in a time-controlled manner, in particular with a relatively high frequency, that is to say normally quite frequently and clearly before a high differential pressure is reached.

It is pointed out that the integration of a precoat device according to the invention is particularly suitable for retrofitting existing filter devices or for installation without drastic design changes to the filter device. It is also possible that a user of the filter device only uses the precoat device or switches it on or makes it possible by inserting the storage container if he has to cope with a filtering task in which, as mentioned in the beginning - problematic results from filtered particles. The user can also choose between

Operation with pre-coating device and operation without pre-coating device to vary.

The invention and embodiments of the invention are explained in more detail below on the basis of schematically illustrated exemplary embodiments. Show it:

Figure 1 is a sectional, first filter device in side view.

Fig. 2 shows the filter device of Fig. 1 in bottom view.

3 shows a second filter device in side view;

Fig. 4 shows the precoat material application device

3 on an enlarged scale and in section;

5 shows a in the precoat material application device of FIG.

4 provided flow block in plan view and on an even larger scale.

The main components of the filter device 2 shown in FIGS. 1, 2 are a housing 4, a plurality of filter elements 6 arranged therein, a collecting space 8 assigned to the housing 4 below, an inflow flow path 10, an outflow flow path 12 and one further below Integrated precoat device to be described in more detail. A conventional suction fan (not shown) is present in the outflow flow path 12 or in the clean gas chamber 18 mentioned below. The components of the usual system for cleaning the filter elements 6, each with a brief air blast against the other direction of flow of the gaseous medium through the filter device 2, are not shown, nor is the control for the cleaning processes and for the precoating processes. The housing 4, viewed without the collecting space 8, has a substantially cuboid shape. The collecting container 8 is connected via a funnel-like transition region 14 in the form of an inverted truncated pyramid (alternatively inverted truncated cone), which also has a cuboid shape (alternatively cylindrical shape), but is significantly smaller than the actual housing 4. The collecting space 8 is - with the exception of one later Cable duct to be described - closed at the bottom, but can be removed from the transition area 14 for emptying. Several filter elements 6, in the example shown eight filter elements

6, are arranged in a parallel arrangement inside the housing 4 (see FIG. 2). Roughly speaking, the filter elements each have the shape of a narrow box in which the upper of the six sides is open. The filter elements 6 are each attached to a horizontal partition 16 of the housing 4, the

"Box interior" of each filter element 6 is connected via a corresponding opening in the partition 16 to the clean gas space 18 of the filter device located above the partition 16. Below the partition 16 is the raw gas space 20 of the filter device 2. The filter elements 6 are each with their

“Box outer sides” boundaries of the raw gas space 20 and with their “box inner sides” boundaries of the clean gas space 18. During the filming, a layer of filtered particles (not shown) that gradually increases in thickness builds up on the box outer sides of the filter elements 6. When cleaning is mentioned, the filtered particles fall down into the collecting space 8.

In the illustrated embodiment, a storage container 22 is fastened centrally in the interior of the collecting container 8. Near its bottom bottom, but spaced from it, is in the reservoir

22 a horizontal fluidizing plate 24 is arranged.

A bit above the fluidizing plate 24 is a horizontally aligned injector 28, which is the beginning of one from the inside of the Storage container 22 forms through the wall of the collecting container 8 leading line 30, with associated driving nozzle 26. The line 30 opens at its other end somewhat in front of the housing 4 of the filter device 2 into the inflow flow path 10. The storage container 22 is open at the top, so that a part of the particles falling down when the filter elements 6 are cleaned reaches the storage container 22.

The driving nozzle 26 is connected to a compressed air line 29, from which a connecting line 27 to the space between the bottom of the

Storage container 22 and the fluidizing plate 24 leads.

When the precoat device is activated, e.g. by opening a valve in the compressed air line 29, the particles located in the storage container 22 in the area of the injector 28 are loosened by means of the compressed air flowing through the fluidizing plate 27 and discharged through the injector 28 and the line 30 in a certain amount per unit of time. The discharged particles enter the flow of the medium to be filtered in the inflow flow path 10 and consequently reach the inflow surfaces of the filter elements 6.

If the particles do not tend to cake, the fluidizing plate 24 is not necessary. In the case of particles which can be discharged without problems through the line 30, the injector 28 is unnecessary.

Since the storage container 22 has an overall open upper side, it is filled up vigorously by particles which are obtained during cleaning. If you do not want this, you can, for example, provide a partially closing lid or an upper closure with openings or even a completely covering lid with only small ventilation openings for pressure equalization. Another variant is shown in dashed lines in FIG. 2. In this variant, the storage container 22 is accommodated in a lateral extension 32 of the storage space 8, its upper side being spaced above it leading oblique surface of the transition region 14 is covered, but is still open to the extension 32 and thus to the interior of the collecting container 8 for the purpose of pressure equalization. In this variant, one can choose whether the storage container 22 as a whole or a larger piece or a smaller piece or not at all is pushed with its open upper side into the upwardly open shaft space of the collecting container 8. The extent to which it is moved in determines whether and how large a portion of the filtered-out particles falling off during cleaning get into the storage container 22.

As an alternative, one can work entirely without a storage container 22. The line 30, possibly with an injector 28, then opens into the interior of the collecting container 8.

Similar to the embodiment according to FIGS. 1, 2, FIG. 3 shows a filter device 2 with the main components housing 4, collecting space 8 for filtered out particles, inflow flow path 10 and, in contrast to the first exemplary embodiment, a precoat device mounted on the outside 40.

The structure of the precoat device 40 can best be seen in FIG. 4. It has a storage container 22 which is cylindrical in the lower region and conical in the upper region with a taper downwards. There is a near the lower end of the storage container 22

Fluidizing plate 24. Somewhat above the fluidizing plate 24 is the beginning of the line 30, which leads through the wall of the storage container 22 to the outside and from there into the inflow flow path 10. The reservoir 22 is closed at the top by a lid 44. In addition, you can see a bypass line 42, the space below the

Lid 44 (where it is not filled with precoat material) connects to the area before the described beginning of line 30. Finally, you can see a driving nozzle 26 analogous to the first embodiment. FIG. 5 shows in more detail how the drive nozzle 26, the bypass line 42 and the line 30 are connected to one another, with the aid of a flow block 46; this detail was not shown in FIG. 4 for the sake of clarity, but was only indicated with the circle A. 5 that the driving nozzle 26 and the

Initial section of line 30 is flush and horizontal. The bypass line 42 comes from obliquely above and then opens into the flow block 43 from the side either horizontally or obliquely from top to bottom. On the side opposite the mouth of the bypass line 42, the flow block 43 has a suction opening

45 for precoat material.

It is particularly pointed out that the interior of the storage container 42 and the raw gas space of the filter device 2 are connected to one another by a pressure compensation line 46. The flexible

Pressure equalization line 46 penetrates the cover 44 and ends a little below the cover 44.

The lid 44 is connected to the storage container 22 by means of a quick-action lock, so that it can be used for refilling

Precoat material can be easily removed.

In addition, a level indicator 48 is provided on the storage container 22. If the level of the precoat material drops below the level defined by the location of the level indicator 48, z.

B. activated an optical or an acoustic warning signal. It can be provided that, for. B. after a defined period of z. B. 1 hour, the filter device 2 is then automatically switched off.

Claims

claims

1. A filter device for filtering out solid particles from a gaseous medium, comprising:

(a) a housing (4) in which at least one filter element (6) is arranged, which borders on a raw gas space (20) with the inflow side and borders on a clean gas space (18) on the outflow side, and in which a collecting container (8) assigned for the filtered out particles;

(b) an inflow flow path (10) for the unfiltered medium to the raw gas space (20);

(c) and an outflow flow path (12) for the filtered

Medium away from the clean gas space (18), characterized in

(d) that a line (30) for transporting precoat material from the collecting container (8) or from a storage container (22) which is at least substantially at the same internal pressure as the collecting container (8) into the inflow flow path (10 ) is provided.

2. Filter device according to claim 1, characterized in that the storage container (22) is positioned in the collecting container (8).

3. Filter device according to claim 1 or 2, characterized in that the storage container (22) is open at the top in such a way that when the at least one filter element (6) is cleaned, particles which have been filtered out partly get into the storage container (22).

4. Filter device according to claim 3, characterized in that the extent of the opening of the storage container (22) and / or the positioning of the storage container (22) can be varied to the

Vary the amount of particles entering the storage container (22) during cleaning.

5. Filter device according to at least one of claims 1 to 4, characterized in that the storage container (22) outside the housing (4) and the collection container (8) is positioned.

6. Filter device according to claim 5, characterized by a pressure compensation line (46) between the storage container (22) and the raw gas space (20) or the collecting container (8).

7. Filter device according to at least one of claims 1 to 6, characterized in that at the beginning of the line (30) for transporting precoat material in the collecting container (8) or in the storage container (22) an injector (28) is provided for discharging precoat material is.

8. Filter device according to at least one of claims 1 to 7, characterized by a bypass line (42) between the not filled with precoat, the upper region of the collecting container (8) or Storage container (22) and the area before the beginning of the line (30) for transporting precoat material.

9. Filter device according to claims 7 and 8, characterized in that a flow block (43) is provided at the beginning of the line (30) for transporting precoat material, on the inlet side a driving nozzle (26) of the injector and one end of the bypass line (42 ) are connected to which the line (30) for transporting precoat material is connected on the outlet side and which has at least one suction opening (45) for precoat material.

10. Filter device according to at least one of claims 1 to 9, characterized in that in the collecting container (8) or in the storage container (22) a fluidizing plate (24) is provided in order to loosen up the precoat material to be discharged through the line (30).

11. Filter device according to at least one of claims 1 to 10, characterized by a control device for the precoat process, with which a precoat phase, preferably for a certain period of time, can be activated after a cleaning process.

12. Filter device according to at least one of claims 1 to 11, characterized by a control device with which precoat processes, either discontinuously or continuously, can be activated in a time-controlled manner.