Liquid separation equipment

The invention relates to liquid separation equipment generally for the separation of the components of a liquid mixture having two components of different density, especially for filtering oil-type contamination from water, e.g.: precipitation water, exceeding many times its own quantity, especially for trapping oil on the surface of trace-line engineering structures mixed with precipitation water and/or oil sticking to solid grains, and preventing by this water-courses receiving precipitation water from becoming contaminated with oil, which liquid separation equipment is built in the way of the precipitation moving towards the receiving water-course, generally in an open-surface channel or ditch and it is paired with a receiving structure installed in the channel or ditch, the receiving structure has a reception side suitable for letting in the contaminated mixture, an intermediate space suitable for separation, and an outlet side suitable for letting out clean water, and the intermediate space does not have a filter or in a different case it has an oleophilic and hydrophobic filter and/or it contains a replaceable filter-box having such filter favourably encased in a framework.

Wastewaters containing oil and grease are created on many fields of life. Some of them are created in installed industry, such as crude oil production, during the transportation and processing of oil, in metal industry, in energy production (in power plants), in chemical plants while another part of them are created mainly on the surface of trace-line engineering structures, such as roads and bridges.

In both cases environmental protection measures need to be taken in respect of wastewaters containing oil, because if they enter receiving water-courses, especially so-called live water, unclean, they may seriously impair their cleanness and endanger the flora and fauna. Experience shows that if such mixtures enter the ground water, due their "penetration ability" and long decomposition period they can contaminate the soil on enormous areas.

The dangers of wastewaters discharged by installed industries have been observed since the end of the 19 ^th century, and different so-called separators were developed. Such separators are described in patent descriptions no. US 745.519, US 925.834, US 995.521 and 1,032.458, which are exactly one hundred years old, and they were able to retain a significant part of the oil content of discharged wastewater.

Development has been uninterrupted ever since then, more and more perfect separators have been created utilising the different density of the two components of liquid mixtures. Such solutions are described in patent descriptions no. US 3,933,654, US 4,132,645, US 4,422.931, US 4,938.878, US 4,980.070 and US 5,348.648.

Interestingly the significance of oil removal from wastewaters contaminated with oil created in nature, more precisely from precipitation water was recognised at a later point. A simple and creative solution is described in patent specification no. HU 209.763 from the 1990's. In principle it can be used both in respect of industrial wastewaters and trace-line engineering structures. It is extremely favourable, because it does not need any machine equipment or human control, unlike the solutions above, as separation is solved with high efficiency and an unlimited lifetime simply with the appropriate geometrical positioning of the overfall crests. However, its disadvantage is that basins of a specific construction need to be built for its operation, in which basins separation takes place.

Facilities containing filter layers in the form of special insert materials suitable for trapping oil, such as ground materials, granules, cushions, etc. of mineral origin or produced artificially in another case, first of all with oleophilic and hydrophobic characteristics, operate on a different principle, and they are especially for the purpose of separating oil precipitation water and oil contamination on the surface of trace-line engineering structures.

Pearlite is a filter material used for a long time, with the help of which the environment damaging component can be removed from the precipitation water of drainage ditches contaminated with oil. Such a solution is described in patent specification no. HU 216.216.

Its cleaning effect is exerted in such a way that in the way of the precipitation water contaminated with oil transversal nests are constructed in the drainage ditches, one or more of which nests - as necessary - is equipped with an insertable pearlite box. In the boxes there is

hydrophobic pearlite with a grain size between 0.5 and 2.0 mm for trapping and filtering out oil.

In practice these pearlite box filters did not prove to be efficient for several reasons. One of the reasons is that on the surface of roads and bridges oil does not appear on its own, but rather stuck to solid grains (e.g.: dust, rubber crumbs, etc.). Therefore such oil is not liable to floating or settling, so in most cases it does not even get as far as the pearlite boxes.

The other unfavourable phenomenon is that when there is a large amount of precipitation water, its decisive majority avoids the pearlite box (e.g.: falls over it). The unsuitability of the solution is increased by the fact that the contamination sets on the surface of the filter and does not even get inside it.

The solution described in patent specification no. HU 2904 U is also for reducing the oil content of laterally flowing precipitation water contaminated with oil. In this case replaceable filters are placed in the drain holes beside the road surface. In the holes there are filters with oleophilic and hydrophobic characteristics, and the water passing through them moves on in the drainage ditch. As a large number of drain holes are needed, the cost-efficiency of cleaning is doubted.

The aim of the invention is to develop environmental protection equipment suitable for the simple and economical separation of the oil content of precipitation water falling on the surface of mainly trace-line engineering structures, such as roads and bridges, and getting contaminated with oil or oil derivatives, in a more efficient way than before. The task of the invention also involves that the equipment, on the basis of its structural construction, should be suitable for being paired with prefabricated reception structures and already existing structures, such as the pearlite oil trapping structures that have proved to be inefficient.

The idea behind the invention is based on the recognition that if filter-boxes having a different construction than the known ones are placed in the precipitation water drainage channel or ditch from the direction of the trace-line engineering structure, and a material suitable for making oil drops coagulate - and float - and also for trapping settling and floating contamination is used as a filter, then the task can be solved.

It also forms a part of the recognition that the filter-boxes and the structures accommodating them should be favourably constructed in a way suitable for reducing the flow-rate of the contaminated water and increasing by this the time spent passing through them. As a result of this the conditions of floating contaminating oil are improved.

In accordance with the set aim the liquid separation equipment according to the invention generally for the separation of the components of a liquid mixture having two components of different density, especially for filtering oil-type contamination from water, e.g.: precipitation water, exceeding many times its own quantity, especially for trapping oil on the surface of trace-line engineering structures mixed with precipitation water and/or oil sticking to solid grains, and preventing by this water-courses receiving precipitation water from becoming contaminated with oil, - which liquid separation equipment is built in the way of the precipitation moving towards the receiving water-course, generally in an open-surface channel or ditch and it is paired with a receiving structure installed in the channel or ditch, the receiving structure has a reception side suitable for letting in the contaminated mixture, an intermediate space suitable for separation, and an outlet side suitable for letting out clean water, and the intermediate space does not have a filter or in a different case it has an oleophilic and hydrophobic filter and/or it contains a replaceable filter-box having such filter favourably encased in a framework, - is constructed in such a way that in front of the filter- box, on its part facing the reception side of the equipment, a replaceable frontal delimiting board is inserted, or in a given case the filter-box is encased between the frontal delimiting board and a replaceable additional filter unit situated on the part facing the outlet side of the equipment, the joint unit of the frontal delimiting board, the filter-box and, in a given case, the additional filter unit applied is set in the intermediate space of the reception structure, and in a given case the filter-box is supplemented with a secondary overfall wall on the outlet side of the equipment.

A further feature of the liquid separation equipment according to the invention may be that the reception structure is a prefabricated reinforced concrete structure, which has connection points facilitating its installation, such as transport hooks, an intermediate space suitable for accommodating the filter-box, and an overfall wall favourably situated on the reception side suitable for allowing the cleaned water to move on.

In the case of a different construction the reception structure is an already existing monolithic reinforced concrete structure, which has an intermediate space suitable for accommodating the filter-box. In this case a secondary overfall wall forming a supplementary part of the filter- box is constructed on the outlet side of the reception structure suitable for allowing the cleaned water to move on.

The filter-box has a self-supporting frame, at least one but favourably two submerging walls transversal with respect to the flowing direction of the contaminated mixture, a casing parallel to the flowing direction of the contaminated mixture, handling ears suitable for placing the filter-box inside the reception structure and removing it from there, and supporting rods defining the position of the filter placed at least in one layer and keeping the filter on its place at the same time.

In the case of a favourable construction of the equipment the filter-box lies at the bottom of the intermediate space of the reception structure, and its casing leans against the longitudinal wall of the reception structure. The frontal delimiting board has a supporting frame, a cover plate encasing the two sides of the supporting frame constructed from strips shifted with respect to each other, and a lifting handle facilitating its placement and removal.

The additional filter unit has a cassette body with a filter placed inside it, supporting rods defining the position of the filter and keeping it in position on one side, a fastening grid fixing the filter on the other side, and lifting handles facilitating the placement and removal of the additional filter unit.

The liquid separating equipment according to the invention has a series of favourable characteristics as compared to the structures known before and used for a similar purpose. Some of the advantages are technical, some are economic, and they can be clearly proved both in the case of the construction paired with a prefabricated reception structure and in the case of the reconstruction of already existing monolithic structures, e.g.: pearlite oil traps, into more efficient structures.

Experiments prove that the advantages are all due to the structural construction. The most important advantage is that the so-called secondary overfall wall - forming a part of prefabricated reception structures, but belonging to the filter-box in the case of already

existing monolithic structures - result in backwater on the reception side of the equipment.

This backwater has several consequences, all of which are favourable.

On the one part it is favourable that a natural settling area is created, where the sludge containing a significant part of the contamination is settled in advance. The retained sludge can be taken away in a simple and easy way, both the capacity and efficiency of the equipment are high, and beside floated contamination it is also suitable for trapping bed load. Another favourable characteristic feature is that the equipment can be very easily and quickly installed or re-installed at a different location. Another advantage is that it operates reliably without any supervision, it is not sensitive to the effects of the weather, and in the case of using a so-called coalescent filter it is enough to clean it every six months.

A remarkable economic advantage of the equipment is that its investment costs are significantly lower than in the case of other known solutions, it does not require a complicated construction technology or special transportation conditions. It is also favourable that a minimal amount of earth needs to be moved and an elevator with a relatively low capacity is enough for its installation, and it is suitable for the cheap and continuous realisation of oil removal even in the case of very different amounts of water discharge without making any structural changes.

Below the invention is described in detail in connection with construction examples, on the basis of drawings. In the attached drawings

figure 1 : the equipment according to the invention placed in a prefabricated reception structure, in axonometric view from the direction of its reception side, figure 2: the same structure in axonometric view from the direction of its outlet side, figure 3: the axonometric view of the frontal delimiting board, figure 4: the front view of the frontal delimiting board, figure 5: the top view of the delimiting board, figure 6: the axonometric view of the additional filter unit, figure 7: the front view of the additional filter unit, figure 8: the section taken along plane VIII-VIII as shown in figure 7, figure 9: the section taken along plane IX-IX as shown in figure 7, figure 10: the fastening grid of the filter,

figure 11 : the filter-box from the direction of the front delimiting board, figure 12: the filter-box from the direction of the additional filter unit, figure 13: the front view of the filter box, figure 14: the section taken along plane XIV-XIV as shown in figure 13, figure 15: the section taken along plane XV-XV as shown in figure 13, with a single-layer filter, figure 16: the same with a double-layer filter, figure 17: the lateral view of the filter-box, figure 18: the equipment according to the invention placed in a monolithic reception structure in axonometric view from the direction of its reception side, figure 19: the same structure in axonometric view from the direction of its outlet side figure 20: the filter-box from the direction of the frontal delimiting board, figure 21: the filter-box from the direction of the additional filter unit, figure 22: the front view of the filter-box, figure 23: the section taken along plane XXIII-XXIII as shown in figure 22, figure 24: the section taken along plane XXIV-XXIV as shown in figure 22, with a single- layer filter, figure 25: the same with a double-layer filter, figure 26: the lateral view of the filter-box.

Figure 1 shows the filter-box 105 from the direction of the reception side of the reception structure 104 made of prefabricated reinforced concrete, in a position placed inside its intermediate space 104a. The filter-box 105 is encased by the frontal delimiting boards 101 that can be grasped using lifting handles 101a and the additional filter units 102 that can be grasped using lifting handles 102a. The reception structure 104 can be prefabricated either in a concrete factory, or on the site near the trace-line engineering structure. The filter-box 105 can be placed in a channel or ditch running along the trace-line structure in an optional position suspended on the transport hooks 104e anchored into the longitudinal walls 104b. The filter-box 105 lies at the bottom 104c of the intermediate space 104a.

Figure 2 shows the same reception structure 104 in top view from the direction of its outlet side. From this direction the additional filter unit 102 between the supporting blocks 104f and the filter-box 105 can be seen as well as the overfall wall 104d, through which the passing

water leaves the structure 104. The overfall wall 104d is suitable for cleaning the wastewater from which the oil has been removed by the filter-box 105 in an additional step.

Figure 3 shows the frontal delimiting board 101, the main parts of which are the supporting frame 101b and the cover plates 101c. On the upper part of the supporting frame 101b there is a lifting handle 101a suitable for moving the whole of the frontal delimiting board 101. The same can be seen in figure 4 on a larger scale in front view, and in top view in figure 5. In both figures it can be seen that the cover plate 101c is formed by parallel strips encasing the supporting frame 101b in such a way that they are shifted with respect to each other on the frontal and rear side of the supporting frame 101b.

Figure 6 shows the additional filter unit 102 again in axonometric view with the cassette body 102d, with the supporting rods 102c fixed between its longitudinal edges and with the lifting handle 102a. The additional filter unit 102 is shows on a larger scale in front view in figure 7, in horizontal section in figure 8 and in vertical section in figure 9.

In the figures showing the rear delimiting board 102 described above the encased filter fixed in the cassette body 102d is not shown. On the one side it is held in position by the supporting rods 102c fitted in the cassette body 102 in a fixed position - favourably welded -, while on the other side it is held in position by the removable fastening grid 102b. The simplest way of constructing the fastening grid 102b is by welding together steel rods crossing each other. It is shown in figure 10.

The filter-box 105 is shown in figure 11 without the reception structure 104, but together with the frontal delimiting board 101 and the additional filter unit 102 from the direction of the reception side, and in figure 12 it is shown from the direction of the outlet side in axonometric view. Similarly to figures 1 and 2, in the present construction example too the equipment is composed from two half parts, in which two filter-boxes 105 are encased each by a frontal delimiting board 101 and an additional filter unit 102.

The view of the filter-box 105 from the direction of the reception side of the reception structure 104 is shown in figure 13, its horizontal section is shown in figure 14, and its vertical section is shown in figure 15. The supporting structure of the filter-box 105 is formed

by the self-supporting frame 105a, between the two extreme members of which there is the submerging wall 105b, and below the submerging wall 105b there is the passage gate 105h.

The precipitation water from which oil needs to be removed arrives in the filter-box 105 from the direction of and through the frontal delimiting board 101. The frontal delimiting board 101 itself does not have a filtering role, but its presence is important from several aspects. It plays a power-breaking, frost-protecting and shading role. The latter means the protection of the filter material against UV radiation.

After the water-flow has been slowed down on the frontal delimiting board 101, the water passes through the filter 103, which, due to its oleophilic and hydrophobic characteristics, is able to "stop" floating "micro" oil drops. These drops gradually coagulate into increasingly larger drops, and they enter the floating space 105g following the filter 103.

The water to be cleaned continues to travel through the passage gate 105h situated below the submerging wall 105b extending into the floating area 105g from the top, and then through the overfall hole 105i above the overfall wall 105c it enters the overfall space 105j. Then the water flows towards the additional filter unit 102.

The additional filter unit 102 may be "empty" as shown in figure 15, or it may be equipped with a filter 103a as shown in figure 16. The latter construction example is suitable for improving the efficiency of cleaning even further. The filter 103 a is encased by supporting rods 102c on its frontal side considering the direction of flow, and by the elements of the fastening grid 102b on its rear side.

In figure 16, on a larger scale, it can be seen that the position of the filter 103 of the filter-box 105 is defined by the supporting rods 105f, and that the water leaving the additional filter unit 102 used in the given case leaves the filter-box 105 through the discharge gate 105k below the overfall wall 105b.

Figure 17 shows the filter-box 105 from the direction of the casing 105d forming the end walls parallel to the direction of flow. Along the casing 105d the filter-box 105 touches the longitudinal walls 104b bordering the intermediate space 104a of the reception structure 104.

The handling ears 105e facilitating the placement and removal of the filter-box 105 in and from the reception structure 104 can be seen in figure 17.

In the case of another possible construction of the liquid separation equipment according to the invention there is no need for manufacturing prefabricated reception structures 104, as instead of them already existing monolithic reinforced concrete structures can be used; for example structures that used to form parts of the so-called "pearlite oil traps". Examples of this are shown in figures 18 and 19.

The already existing monolithic reinforced concrete reception structure 104 and the filter-box 105 placed inside it is shown in figure 18 from the direction of reception as the water flows, while it is shown in figure 19 from the direction of the outlet side in axonometric view. As originally the structure 104 did not have an overfall wall marked 104d in the former construction example standing in the way of the leaving water, here the filter-box 105 needs to be supplemented with a further (secondary) overfall wall 105c.

It can be seen in both figures that in this case again the filter-box 105 is encased by a frontal delimiting board 101 and an additional filter unit 102. It is confirmed in figures 20 and 21, where the filter boxes 105 are shown without the reception structure 104.

The filter-box 105 forming the main unit of the equipment is made of two half-boxes in this case again, its view from the direction of the outlet side is shown in figure 22, its horizontal section is shown in figure 23, its vertical section is shown in figure 24, its more detailed drawing is shown in figure 25, and the lateral view of the filter-box 105 is shown in figure 26.

The structural arrangement, the method of installation in the structure 104, and the operation of the equipment itself is the same as in the case of the first type of construction. There is no difference in the material of the filter used, or in respect of the fact that a single or double layer can be placed in the way of the water to be cleaned. Experience shows that no significant difference can be observed in the frequency of filter regeneration either.

The liquid separation equipment according to the invention is to be installed first of all beside trace-line engineering structures, such as roads, railway lines and bridges, for the purpose of removing hydrocarbon contamination from such surfaces, but it is also suitable for use in the

drainage system of pools, settling basins or reservoirs, and for retaining all types of contamination capable of floating.

Its significance lies first of all in its structural construction, in the fact that it is easy, quick and simple to install or re-install at a different location, and in its cost-efficiency both from the aspect of investment and maintenance costs.