Untitled record

Modular filter tower

The invention relates to a modular filter tower for filtering an air stream.

During certain operating processes, an air flow can arise that is contaminated with various components, such as dust particles and harmful gases, such as, for example, ammonia gas.

Since such a polluted air stream cannot be emitted untreated into the environment, it is required that such an air stream is first filtered.

To this end, it is known to pass the air stream through, for example, a scrubber, in which, for example, dust particles and some gases are filtered from the air stream. A screen of water or other liquid is usually formed in a scrubber, for example by means of sprayers, and the polluted air is passed through this screen. Due to the large contact surface between the liquid screen and the air to be filtered, a large part of the contaminants is absorbed in the liquid, after which the liquid with the contaminants can be further processed and the filtered air can be emitted. Instead of a liquid, it is also possible to spray a dry substance with which an air stream can also be cleaned.

Another method for cleaning a contaminated air stream is by passing the air stream through a filter bed. A filter material is provided on the filter bed, which filters the pollutants. A known filter material is biomaterial, which consists of vegetable parts, such as, for example, heather. Bacteria are present on the biomaterial, which can remove the contaminating parts from the air stream. To this end, it is important that the contaminated air stream is in contact with the biomaterial for a sufficient length of time.

In practice, a large tank with a grid floor is installed for such a bio-filter system. In a typical application, the tub can quickly have the size of a competition pool. The biomaterial is applied to the grid and the polluted air is blown into the container under the grid floor. The air must then spread evenly under the grid, after which the air flows up through the biomaterial.

If the filter material is not evenly distributed on the slatted floor and has no homogeneous density, there will be places in the filter bed where the air flows through the filter bed faster than in other places. Thus, optimum use is not made of the filtering effect of the filter material.

Of course, the thickness of the layer of filter material can be adjusted, but then parts of the filter bed continue to be used less well than other parts of the filter bed.

It is now an object of the invention to reduce or even prevent the abovementioned disadvantages.

This object is achieved according to the invention with a modular filter tower, which comprises: - a number of treatment modules placed one on top of the other with a prism-shaped housing with a bottom, an upright wall arranged along the circumference of the bottom and an upper wall arranged on the upright wall, the housing has an air supply opening near the bottom and an air outlet opening near the top; - wherein at least one treatment module has a grid for supporting biomaterial arranged in the housing parallel to the bottom and above the air supply opening, - wherein at least one treatment module comprises a scrubber arranged in the housing.

A prism-shaped housing is understood to mean a housing in the form of a prism. It is preferably a straight prism in which the connecting ribs and side surfaces are perpendicular to the ground planes. This means that the connecting side surfaces are rectangular. Optionally it is also possible to opt for modules in the form of a crooked prism, wherein the connecting ribs and side surfaces are not perpendicular to the ground surface.

The use of a modular structure of the filter tower has the advantage that the filter tower can easily be adapted to the air flow to be filtered. The filter tower can also be easily adjusted if a business process changes as a result of which the contamination of the air flow changes or if the requirements for being allowed to emit an air flow change. This adjustment can for example be done by adding an additional treatment module or by exchanging one type of treatment module with the other type of treatment module.

Due to the modular construction, a considerable saving can be achieved in particular for a filter based on biomaterial. This is achieved by placing two or more biomaterial treatment modules one above the other in one embodiment. For example, the air to be filtered is passed through a biomaterial filter a number of times as opposed to a conventional biomaterial with a large tank, where the air is only passed through the filter once. Because according to the invention the contaminated air stream is passed through a biofilter a number of times, this air can mix again between the treatment modules, so that a homogeneous air stream always passes through each treatment module. For example, it is possible to save up to 60% on the use of biomaterial compared to a conventional filter bin.

With the treatment module, which is equipped with a scrubber, dust particles and any harmful gases can be removed from the air stream. By using a combination of both at least one treatment module with grid for biomaterial, and at least one treatment module provided with a scrubber, the filter tower can easily be optimized for filtering a specific air flow.

Furthermore, a large space saving is realized with the filter tower since the footprint of a filter tower according to the invention is considerably smaller in comparison with conventional filter systems with the same filter capacity.

In a preferred embodiment of the modular filter tower according to the invention, a first treatment module with grid is placed on a second treatment module with scrubber and connects the air outlet of the second treatment module to the air supply opening of the first treatment module.

By first passing the air stream to be treated past a treatment module with scrubber, dust particles and at least a part of harmful gases can be filtered. The next treatment module with grid can then filter the remaining part of harmful gases. Because fewer dust particles are present in the air, the biomaterial will therefore be sufficiently permeable to air for a long time to be able to filter and the biomaterial will need to be replaced less quickly.

In a further preferred embodiment of the modular filter tower according to the invention, spraying means are provided in at least one treatment module with grid for humidifying biomaterial applied to the grid.

For the biomaterial to function properly, it is often necessary to keep the biomaterial moist. Because a lot of air flows through the biomaterial, the necessary moisture will also evaporate. The moisture content in this embodiment can therefore easily be maintained by means of the spraying means.

In another embodiment of the modular filter tower according to the invention, the air supply opening is an opening in the bottom. The edge of this opening can thereby fully abut against the circumferential wall. This actually provides a module with a completely open bottom.

In yet a further embodiment of the modular filter tower according to the invention, the air discharge opening is an opening in the top wall. Also here, preferably, the edge of the opening in the upper wall lies substantially entirely against the peripheral wall.

When both the air supply opening is arranged in the bottom and the air discharge opening is arranged in the top wall, the treatment modules are connected to each other when stacked on top of each other, so that the air can easily flow through the filter tower from the bottom upwards.

A further preferred embodiment of the modular filter tower according to the invention further comprises a foot module for supporting the treatment modules placed one on top of the other, said foot module comprising a side inlet for introducing air and an air discharge opening arranged on the top for connection to an air supply opening of an air inlet opening on the foot module placed treatment module.

The foot module can for example be anchored on a concrete floor and ensure that the filter tower is stable. Via the side inlet, the air flow to be filtered can be led to the air outlet opening arranged at the top, after which the air can flow from below through each treatment module.

The invention further relates to a combination of a filter tower according to the invention and biomaterial, wherein the biomaterial is arranged on the gratings of the relevant treatment modules.

The biomaterial preferably comprises heather and fiber peat. These materials offer a good basis and the right bacteria to filter harmful gases such as ammonia from an air stream. The ratio between the amount of heather and fiber peat can be adjusted depending on the desired filtering.

These and other features of the invention are further elucidated with reference to the accompanying drawings.

Figure 1 shows a perspective view of an embodiment of a modular filter tower according to the invention.

Figure 2 shows a schematic cross-section of the filter tower according to Figure 1.

Figure 1 shows a perspective view of a filter tower 1 according to the invention. The filter tower 1 has a foot module 2, a scrubber module 3 and two biomaterial modules 4. Each module 2, 3, 4 has a prismatic housing, in particular block-shaped. An inspection hatch 6 is provided in the upright wall 5 of each module 2, 3, 4.

Furthermore, the modules 2, 3, 4 are placed between vertical uprights 7 to give the filter tower 1 extra stability.

Each module 2, 3, 4 is open on both the bottom and the top. A raised edge 8 is then provided on the top side, on which a next module can be placed and which moreover centers this module.

The foot module 2 has a side inlet 9 with which the air flow L to be treated can be introduced into the filter tower 1. This air L is dispersed in the foot module 2 and flows out at the top, via an air discharge opening and thus enters module 3 via the air supply opening in the underside of the scrubber. Furthermore, a receptacle 13 is provided in the foot module 2 with which water seeping through from the filter tower 1 can be collected and discharged via drain 14.

Three nozzles 10 are provided in the scrubber module 3, which form a water screen 11. The nozzles 10 are supplied with water via a water pipe 12.

The air L flows through the water screens 11, through which dust and some of the harmful gases are filtered. The water can be recirculated within the scrubber module 13 to the water pipe 12 or can be collected in the base by the collecting tray 13.

Subsequently, the air L at the top of the scrubber module 3 flows out via the air outlet opening and enters the biomaterial module 4 placed above the relevant air inlet opening.

In the biomaterial module 4 a grid 15 is arranged near the bottom, on which a layer of biomaterial 16 is arranged. Sprayers 17 are furthermore provided above the layer of biomaterial 16, with which the biomaterial 16 can be kept moist. The air L flows from the scrubber module 3 through the grid 15 through the biomaterial 16. The bacteria in the biomaterial 16 ensure a further filtering of the passing air L.

In order to obtain further filtering, the air L passes from the lower biomaterial module 4 through a second biomaterial module 4 placed on top of it, whereafter the air L is discharged at the top of the filter tower 1.