WO1998011268A1

WO1998011268A1 - Flue gas capturing system

Info

Publication number: WO1998011268A1
Application number: PCT/AT1997/000194
Authority: WO
Inventors: Willi Kopf; Heinz-Günter KORNRADE
Original assignee: Brunner Verzinkerei Brüder Bablik Gesellschaft Mbh
Priority date: 1996-09-09
Filing date: 1997-09-09
Publication date: 1998-03-19
Also published as: AU4104197A; AT404983B; ATA159096A

Abstract

The invention concerns a flue gas capturing system which has a surrounding housing (5, 14) with a specially discontinued flue gas emitting source (13), for instance a galvanising bath. The housing has preferably rather long groove (25) at the top (14) for a carrying device, for instance for the carrying rope (20) of a crane (18). The capturing system also comprises at least one opening in the wall for suctioning (7) and a collecting main (30, 22) which is connected to the suctioning device inside (6) the housing. Preferably, between the opening and/or openings in the wall for suctioning (7) and the suctioning device, a filtering device is connected to the collecting main (30, 32). Moreover, there is at least one suctioning canal (1) outside the housing. Its opening (26) is located at least partially in the area of the outer rims of the groove (25). The flue gas escaping from the housing (5, 14) through the groove (25) is suctioned by the suctioning canal (1).

Description

Smoke gas detection system

The invention relates to a flue gas detection system with a, in particular discontinuously emitting, flue gas source, e.g. a galvanizing bath, surrounding housing which, preferably in the ceiling of the housing, has a preferably elongated passage gap for a carrying device, e.g. for the suspension cable of a crane system, and with a suction device connected to the interior of the housing via at least one suction wall opening and a collecting line, a filter device preferably being connected between the at least one suction wall opening and the suction device in the collecting line.

The smoke vapors that occur in various work processes often contain harmful particle emissions that can be above the respectively permitted limit value. Problems of this kind have occurred particularly in the galvanizing processes in the metalworking industry. For example, the white smoke generated by galvanizing metal objects by evaporating the middle of the river must be detected and fed to a filter system. Modern systems are equipped with an enclosure that encloses the entire zinc bath area. This consists of a self-supporting steel structure, which is usually passed through in the middle. As soon as the galvanizing material has been introduced into a front door of the housing, the system fan is started up in order to set the suction quantity required for the process. Then the dipping process is carried out, which results in a very strong smoke gas development. This is caused when, when immersed in the molten zinc, the flux adhering to the surface of the galvanized material evaporates into fine-grained sublimation products and into gaseous components. The amount of solids that occurs in the resulting flue gas cloud can be a few 100 mg / m ^J. These emissions are detected by the suction device and passed over the filter device, where the solid components are separated.

Known systems of this type, which bring about a large containment of the otherwise detectable immissions, have a weak point, however, which impairs the good suction result. When immersed in the zinc bath, there is an extremely strong development of flue gas for a short time, in which the existing suction device is overwhelmed. In this relatively short period of time, the passage gap provided in the ceiling of the housing, through which the required crane rope extends, acts as an additional fume hood, through which very large quantities of smoke gases can escape. Through these short moments, the otherwise almost perfectly functioning system is out of balance. A large number of proposals have attempted to solve this existing problem. So were about Passage gap temporary closure cover provided, which could be pushed over the gap during the immersion process. But even this simple mechanical implementation could not exist in the very harsh operating climate of this system. The disadvantage of these solutions, which are obvious at first glance, is that the dust contained in the flue gas cloud has an aggressive effect on all parts involved. As a result, even after a short use of these mechanical covers, for example, the sliding parts required for this fail, so that continuous operation is not possible. An additional air-blowing device in the direction of the suction device inside the housing in the vicinity of the passage gap did not bring about any significant improvement in the harmful emission values.

In addition, care must be taken to ensure that, in many cases, avoiding these emissions to the environment depends on the goodwill of the operator and that the costs of these additional environmental protection measures should be as low as possible.

The object of the invention is therefore to provide a system of the type mentioned at the outset, with which emission of flue gases from the passage gap of the dwelling can be avoided.

Another object of the invention is to provide a system that enables an existing system to be upgraded with a low installation cost.

According to the invention, this is achieved in that at least one suction duct is provided outside the housing, the suction opening of which is at least partially arranged in the region of the outer edge of the passage gap, via which suction duct the smoke gases escaping from the housing through the gap can be extracted.

With this measure, if a particularly strong development of flue gas suddenly occurs, emissions can be prevented from passing through the passage gap in the ceiling of the housing and into the environment. The aggressive dust contained in the flue gas cloud is also extracted, which means that it does not hit any moving mechanical parts and cannot damage them. The positioning of the suction opening, which is particularly effective in terms of flow technology, results in an almost complete reduction of harmful emissions.

In a further embodiment of the invention it can be provided that the suction opening of the at least one suction channel is arranged in the region of one of the two longitudinal edges of the passage gap.

In this way, all of the flue gases emerging from the flue gas source through the passage gap can be effectively sucked in, and yet a relatively simple form of a suction channel can be created, which enables crane ropes to be passed through without hindrance. Another feature of the invention can be that the suction opening cross-section is substantially at right angles to the gap cross-section.

As a result, the smoke gas detection system according to the invention can also be retrofitted into an existing system with little construction effort, and a high degree of efficiency can be achieved with the additional extraction.

An advantageous embodiment of the invention can consist in that the suction opening cross section is approximately the same size as the gap cross section.

A design in this form results in flow velocities for the flue gases to be sucked in, which enable a very efficient implementation of the used suction power.

Another feature of the invention can be that the suction opening cross section is rectangular.

This results in a design of the suction cross section that is simple to carry out, so that it can be assembled from simple sheet metal parts.

Another feature of the invention can be that the suction channel is box-shaped and with a side wall parallel to the housing ceiling, and that the suction opening cross section is formed by at least one longitudinal opening and an outlet cross section by at least one opening on the opposite long side of the box-shaped suction channel, which outlet cross section is connected to another suction device.

Such a box can easily be retrofitted onto an existing housing in order to completely remove the smoke gases that are produced.

Another variant of the invention can consist in that the outlet cross-section is composed of a plurality of longitudinal openings in the intake duct, each opening being led via a funnel-shaped extension into a branch line, which branch lines open into a further collecting line.

By dividing the outlet cross-section into several openings, the suction cross-section, which may be very large, can be suctioned off evenly.

In a further embodiment of the invention it can be provided that the further manifold for the branch lines of the suction channel together with the manifold coming from the housing are guided via a controllable throttle valve into a main line which opens into the suction device.

This measure makes it possible to dispense with a separate suction device of its own and the suction streams are brought together via the wall openings of the housing and the suction channel. A further embodiment of the invention can consist in that a further suction channel is arranged in the area of the other edge of the passage gap opposite one another.

This measure can further increase the efficiency of the additional suction at the passage gap.

In a further embodiment of the invention it can be provided that an air ejection channel is provided outside the housing, and that the ejection opening is arranged opposite the suction opening cross section, the passage gap being located between the ejection opening and the suction opening.

As a result, air can be blown in the direction of the extraction cross section via the discharge opening, whereby the efficiency of the extraction of the flue gases emerging through the passage gap can be increased. This creates an air flow running over the passage gap, through which the flue gases can practically not pass.

In a further embodiment of the invention it can be provided that wooden strips extending in the longitudinal direction, preferably on both sides, are arranged above the suction channel or the air ejection channel and partially covering the passage gap.

These wooden slats arranged in this way reduce the passage gap and, due to their material properties, can also easily be worn away by the suspension cable over time, since the falling parts e.g. do not cause any deterioration in the galvanizing bath. The reduction in the passage gap cross section has the advantage that fewer flue gases can escape from the housing.

The invention is explained in detail below on the basis of the exemplary embodiments illustrated in the drawings. It shows

Fig.l is a side view of an embodiment of a smoke gas detection system according to the invention;

2 shows an oblique view through a further embodiment of a system according to the invention according to FIG. and

3 shows a detail of a further embodiment of the system according to the invention.

In Fig.l a flue gas detection system is shown with a schematic representation of the flue gas flow caused by the suction, the paths traversed by the extracted gas are symbolized by arrows. A discontinuously emitting flue gas source 13, which is fed by the reaction of a galvanizing bath 21 (FIG. 2) when an object is immersed, is surrounded by a double-shelled housing 5, 14, so that an interior space 6 formed by the housing 5, 14 by suction from the Flue gas emissions from the flue gas source 13 can be exempted. To carry out the galvanizing process, an elongated passage gap 25 is provided in the ceiling 14 of the housing 5, 14, through which a supporting cable 20 A crane system 18 (FIG. 2) runs through which the part to be galvanized is moved into the housing and this is immersed in the bath.

When immersed, there is a violent reaction and evaporation or detachment of small particles with the resulting steam in the galvanizing bath. Especially in the case of longer pipes, this sudden flue gas generation is even further intensified by the chimney effect which occurs, since the pipe is immersed at one end and the flue gas which is formed on the zinc bath surface is accelerated upwards as a result of the suction.

For the application of the invention, other methods with a strong smoke gas development are also possible, in which the housing cannot be completely closed due to technical reasons.

To cope with the flue gas occurring during the actual galvanizing process after the immersion phase has been completed, a suction device (not shown) is provided, which is connected to the interior 6 of the housing 5, 14 via a suction wall opening 7, a branch line 4 and a main line 22. Between the suction wall opening 7 and the suction device there is also connected a filter device, not shown, which separates the dust and the smoke particles. In the interior 6 of the housing 5, 14, a negative pressure thus arises which prevents the flue gas from flowing out laterally during operation.

The invention now consists in that a suction channel 1 is provided outside the housing 5, 14, the suction opening 16 of which is at least partially arranged in the region of the outer edge of the passage gap 25. As a result, the smoke gases escaping through the gap 25 from the housing 5, 14 can be extracted via the suction channel 16. The special arrangement of the suction opening 26 makes it possible to suck in the flue gas that otherwise escapes through the passage gap in the case of strong flue gas development and to prevent deposition in the environment outside the housing 5, 14.

In the particular embodiment according to FIG. 1, the suction opening 26 of the suction channel 1 is arranged in the region of one of the two longitudinal edges of the passage gap 25, the suction opening cross section being essentially at right angles to the gap cross section.

However, several suction channels can also be placed above the ceiling of the housing, so that their suction openings are directed towards the passage gap. For example, a further suction channel can be arranged in the region of the other edge of the passage gap opposite one another.

A further possibility of the still improved extraction of smoke gases passing through the passage gap 25 can be seen in FIG. 1. An air ejection channel 2 is provided outside the housing 5, 14, the ejection opening 27 of which is arranged exactly opposite the suction opening cross section 26, the passage gap 25 being located between the ejection opening 27 and the suction opening 26. As a result of this additional measure, air is blown in the direction of the suction cross section 26, as a result of which even more smoke gas particles can be entrained into the suction channel 1.

Furthermore, in FIG. 1 the suction opening cross section 26 is approximately the same size as the gap cross section 25 and the suction opening cross section 26 is rectangular. In this way, there is a uniform suction of the flue gas along the elongated gap 25.

The suction channel 1 is box-shaped and formed with a side wall parallel to the housing ceiling 14, the suction opening cross section 26 being realized by a longitudinal opening and an outlet cross section 29 by an opening on the opposite long side of the box-shaped suction channel 1. Furthermore, the outlet cross section 29 is connected via a short line 8, which widens to a funnel 10, to a further suction device, which is not shown in FIG. 1. As in the exemplary embodiment according to FIG. 2, this further suction device can also be created by allowing another collecting line 31 to open into the main line 22 of the suction device for the interior of the housing 5, 14.

In the exemplary embodiment according to FIG. 2, the main part of the suction is distributed over several wall openings 7 in order to enable the most favorable detection of all smoke gas components of the interior 6 along the gap 25.

Analogously, for a very uniform extraction of the excess flue gases, it is also advantageous to assemble the outlet cross section through a plurality of longitudinal openings 70, each individual opening 70 being guided via a funnel-shaped extension 10 into a branch line 19, which branch lines 19 into the further manifold 31 flow out.

This further manifold 31 is brought together with the manifold 30 coming from the housing 5, 14 by means of a controllable throttle valve in the main line 22, which conducts the collected flue gases to the filter and suction device, not shown. The inner throttle valve can now be adjusted as required so that a distribution of the suction flows which is favorable for the galvanizing process is achieved.

The flue gas flows sucked in via the wall openings 7 form the main part of the suction flows, while a smaller part of the flue gases passes through the outlet openings 29 or openings 70. This corresponds to the effect that the suction channel 1 is to have. It is therefore primarily not used to extract the entire amount of flue gas, but is intended to remove the excess amount of flue gas in the event of sudden strong clouds of flue gas. Accordingly, there is an advantageous dimensioning of the collecting line cross sections 30, 31 when about a third of the suction power is attributed to the suction channel 1 and two thirds of the suction power to the wall openings 7. In this ratio, roughly the cross-sections of the suction lines are to be dimensioned. Depending on the application example, it can also be completely other dimensions of the lines are made to optimize the efficiency of the suction.

In the exemplary embodiment according to FIG. 3, wooden strips 40, 41 are arranged above the suction duct 1 or the air ejection duct 2 and the passage gap 25, partially overlapping on both sides in the longitudinal direction thereof, which further reduce the passage gap 25 and make it more difficult for smoke gases to escape. In contrast to the exemplary embodiment according to FIG. 1, in which protruding rubber lips 43, 44 are provided in the passage gap 25, the wooden strips 40, 41 have the advantage that their wear, which occurs over time due to the back and forth of the suspension cable , only wooden parts or wood chips can fall into the galvanizing bath 21, which do no further damage to it, while rubber components can get into the bath 21 when they are detached from the housing ceiling and can impair its effectiveness.

Claims:

Claims

PATENT CLAIMS

1. Flue gas detection system with a one, in particular discontinuously emitting, flue gas source, e.g. a galvanizing bath, surrounding housing which, preferably in the ceiling of the housing, has a preferably elongated passage gap for a carrying device, e.g. for the supporting cable of a crane system, and with a suction device connected to the interior of the housing via at least one suction wall opening and a collecting line, a filter device preferably being connected into the collecting line between the at least one suction wall opening and the suction device, characterized in that outside At least one suction channel (1) is provided in the housing, the suction opening (26) of which is at least partially arranged in the area of the outer edge of the passage gap (25), via which suction channel (1) the through the gap (25) from the housing (5, 14) escaping smoke gases can be extracted.

2. Smoke gas detection system according to claim 1, characterized in that the suction opening (26) of the at least one suction channel (1) is arranged in the region of one of the two longitudinal edges of the passage gap (25).

3. Smoke gas detection system according to claim 1 or 2, characterized in that the suction opening cross section is substantially at a right angle to the gap cross section.

4. Smoke gas detection system according to claim 1, 2 or 3, characterized in that the suction opening cross section is approximately the same size as the gap cross section.

5. Smoke gas detection system according to claim 1 to 4, characterized in that the suction opening cross section is rectangular.

6. Smoke gas detection system according to claim 1 to 5, characterized in that the suction channel (1) is box-shaped and formed with a side wall parallel to the housing ceiling (14), and that the suction opening cross section through at least one longitudinal opening (26) and an outlet cross section through at least one Opening (29) on the opposite longitudinal side of the box-shaped suction channel (1) is formed, which outlet cross section is connected to a further suction device.

7. Smoke gas detection system according to claim 6, characterized in that the

Outlet cross section is composed of a plurality of openings (29) on the longitudinal side of the intake duct (1), each opening being led via a funnel-shaped extension (10) into a branch line (19), which branch lines (19) open into a further collecting line (31) .

8. Smoke gas detection system according to claim 7, characterized in that the further manifold (31) for the branch lines (19) of the suction channel (1) together with the manifold coming from the housing (5, 14) are guided via a controllable throttle valve into a main line , which opens into the suction device.

9. Smoke gas detection system according to one of the preceding claims, characterized in that a further suction channel is arranged in the region of the opposite one edge of the passage gap (25).

10. Smoke gas detection system according to one of the preceding claims, characterized in that outside the housing (5, 14) an air discharge channel (2) is provided, and that the discharge opening (27) is arranged opposite the suction opening cross-section, wherein between the discharge opening (27) and the suction opening (26) of the passage gap (25).

1 1. Smoke gas detection system according to one of the preceding claims, characterized in that above the suction channel (1) or the air discharge channel (2) and the passage gap (25) partially overlapping, in its longitudinal direction, preferably on both sides, extending wooden strips (40, 41) are arranged.