Filter device

Abstract

Filter device for at least partial treatment of raw water, comprising a raw water inlet, two filter elements connected in series and a downstream water outlet, wherein the first filter element contains an ion exchanger and the second filter element contains a mixture of at least one magnesium salt and a water-insoluble solid, characterized in that at least one separation device is provided for dividing a water stream into two partial streams, of which only one partial stream is passed through the first and / or the second filter element.

Description

[0001] The invention relates to a filter device for the at least partial treatment of raw water, which comprises a raw water inlet, two filter elements connected in series and a downstream water outlet, wherein the first filter element contains an ion exchanger and the second filter element contains a mixture of at least one magnesium salt and a water-insoluble solid

[0002] Ensuring the quality of drinking water is essential for health reasons. Furthermore, especially when concentrations of calcium and magnesium ions are high, it is important to at least partially remove these so-called hardness-forming substances. This is partly because the presence of dissolved minerals causes limescale deposits in household appliances such as washing machines, dishwashers, coffee machines, and water heaters. This can reduce the efficiency of the appliances, increase their energy consumption, and ultimately shorten their lifespan. Furthermore, soap and detergents react with the calcium and magnesium ions in the water, forming poorly soluble residues. This causes detergents to foam less effectively, increasing consumption and impairing cleaning performance.

[0003] In addition, water with a comparatively high mineral content can negatively affect the taste of foods and beverages such as coffee or tea.

[0004] While traditional descaling solutions such as chemical water softening or ion exchange systems have proven effective, they often come with disadvantages such as high maintenance requirements, increased environmental pollution from chemical residues, and increased energy consumption. Innovation in filter treatment technology aims to address these challenges through improved physical and chemical water treatment technologies. These include environmentally friendly ion separation processes, the reduction of limescale deposits using magnetic or electric fields, and sustainable filter media that enable long-term use without frequent regeneration cycles.

[0005] Filter devices with at least one ion exchanger, which reduces the mineral content in the so-called "raw water," are therefore common. The term "raw water," for the purposes of the invention, essentially defines a water stream that has not yet passed through the filter device, but which can, in principle, be of drinking water quality. Both alkaline and acidic ion exchange materials are known, but they are based on the same functional principle: the ion exchanger contains a material capable of absorbing certain ions from a solution and releasing other ions in return. Specifically, the ion exchanger comprises a solid, insoluble material, usually a resin, coated with charged functional groups (positive or negative).

[0006] These functional groups bind specific ions from the solution through electrostatic interactions. When the solution comes into contact with the ion exchanger, the ions present in the water are replaced by ions originally bound to the resin. A cation exchanger, also called an acidic ion exchanger, exchanges positive ions (e.g., calcium or magnesium) for other cations such as sodium or hydrogen, while an anion exchanger exchanges negative ions for other anions such as hydroxide. The selectivity of the ion exchanger depends on the resin's affinity for certain ions. Larger or more highly charged ions are often preferentially bound.

[0007] The problem with the use of cation exchangers is that both calcium and magnesium ions are removed non-selectively. However, for taste reasons, setting a specific concentration range of magnesium ions is often desired, especially when using the treated water for tea and coffee preparation. Therefore, some conventional filter systems use weakly acidic ion exchangers, some of which are loaded with magnesium ions, to replace monovalent or divalent ions from the water being filtered with magnesium ions, as described, for example, in EP 2 094 611 B2.

[0008] It is also known from the prior art to provide a filter element that specifically releases magnesium ions. For example, US Pat. No. 4,732,674 A describes a filter system for water treatment in which the filter medium also includes a mixture of activated carbon and a water-soluble alkali salt such as magnesium carbonate. However, this does not demonstrate a targeted connection to an ion exchanger, in which the solubility product of magnesium carbonate is increased by the generation of free carbonic acid.

[0009] Similarly, EP 1 370 338 A2 discloses a filter material embedded in a matrix based on magnesium silicates, oxides, hydroxides, or phosphates, which releases magnesium ions into the flowing water. However, embedding the material in a matrix results in significant manufacturing complexity.

[0010] EP 1 253 114 A2 also discloses a water treatment system with a replaceable filter cassette, in which an additional filter medium can optionally be supplemented with other components such as magnesium carbonate, thus also increasing the magnesium content in the water. In one embodiment of the water treatment system, it preferably has a bypass, which, however, only allows the supply water to partially bypass the entire filter cassette.

[0011] Finally, EP 3 034 145 A1 describes a multi-zone filter element in which two of the three zones contain an ion exchange element, while the third zone comprises a combination of granulated alkaline earth carbonate (e.g., magnesium carbonate) and activated carbon. This achieves water softening and magnesium enrichment in one device.

[0012] However, all these filter devices have in common that they cannot react to fluctuations in the composition and / or flow rate of the incoming raw water stream. However, the composition of the raw water with regard to the cations it contains has a significant influence on the composition of the water stream leaving the filter device, especially in the case of a downstream enrichment of magnesium ions. This is due to the dependence of the solubility of the magnesium salts on the pH value. For example, an increase in the hardness of the raw water can lead to more cations being exchanged for H in the ion exchanger. +-ions are exchanged. As a result, the pH value drops, which in turn increases the solubility of the magnesium salts. In downstream systems, significantly more magnesium is released into more acidic water. In addition to undesirable changes in taste, in the worst case, this can also lead to agglomeration and thus to the clogging of the affected filter element.

[0013] The invention is therefore based on the object of providing a filter device in which the hardness of the water can be reliably reduced and a constant magnesium content can be set.

[0014] This object is achieved by a filter device according to the invention according to claim 1.

[0015] Such a filter device has a raw water inlet, two filter elements connected in series, and a downstream water outlet, wherein the first filter element contains an ion exchanger and the second filter element contains a mixture of at least one magnesium salt and a water-insoluble solid. In addition, such a filter device has at least one separating device for dividing a water flow into two partial flows, of which only one partial flow is passed through the first and / or the second filter element. The ion exchanger as the first filter element reduces the water hardness. In the second filter element, the magnesium content can then be optimized using the magnesium salt, wherein the magnesium salt is advantageously mixed with an insoluble solid to prevent clumping of the magnesium salt.

[0016] By providing a bypass for both the first and second filter elements, fluctuations in the hardness of the raw water stream can be compensated. In particular, with a high hardness and thus a lower pH value of the water after passing through the ion exchanger, a smaller proportion can be passed through the second filter element, so that the amount of added magnesium ions remains constant despite increased solubility.

[0017] For a compact design, one embodiment of the filter device according to the invention provides for the first and second filter elements to be provided in a common cartridge.

[0018] Arranging the two filter elements in two cartridges, however, offers the advantage of greater maintenance flexibility, as each filter element can be replaced separately. This also reduces waste.

[0019] To simplify the connection of the two filters, a favorable design provides for only one separation device. This separation device is either installed upstream of the first filter element, so that the partial flow passed through the first filter element is passed entirely through the second filter element, or the separation device is installed downstream of the first filter element and upstream of the second filter element. In detail, the second variant is particularly suitable because, depending on the pH value of the water flow exiting the ion exchanger, a portion can be passed through the magnesium enrichment in the second filter element, so that the magnesium concentration of the exiting flow can be easily kept constant.

[0020] However, greater control or regulation flexibility can be achieved by providing two separating devices, the first of which is connected upstream of the first filter element and the second of which is connected downstream of the first filter element and upstream of the second filter element.

[0021] A supplementary or alternative advantageous embodiment of the filter device according to the invention also comprises at least one valve for adjusting the ratio of the two partial flows.

[0022] It is also advantageous if at least one measuring device for detecting the total quantity and the partial flows is provided in a filter device according to the invention, since in this way the expected composition of the at least partially treated water flow can be controlled or regulated.

[0023] In addition, at least one additional filter element can be installed upstream of the raw water inlet or the water outlet. This can include additional elements such as membrane filters (e.g., micro-, ultra-, and nanofilters) or any other known water treatment methods, as well as the use of additional ion exchangers and / or adsorption filters.

[0024] For the filtering effect of the second filter element, it has also been found to be advantageous if the at least one magnesium salt and / or the water-insoluble solid are present as at least two separate granules or as one granule. This prevents agglomeration of the magnesium salt and thus clumping.

[0025] Due to the specific water solubility, it has also been found to be advantageous to use at least partially magnesium silicate, magnesium carbonate, magnesium oxide, magnesium hydroxide, a magnesium phosphate, or a mixture thereof as the magnesium salt, with the use of magnesium carbonate, magnesium hydroxide, magnesium oxide being particularly preferred as very inexpensively available substances.

[0026] Particularly preferred are all embodiments in which the water-insoluble solid contains at least partially activated carbon, as this additionally acts as an adsorption filter. Alternatively or additionally, the water-insoluble solid can also contain a water-insoluble mineral separation or filter medium, for example, a zeolite or silica gel, or a mixture thereof. The at least one magnesium salt and / or the water-insoluble solid can be present either as a loose bed or fixed.

[0027] An acidic ion exchanger is advantageously used as the ion exchanger. A filter device designed according to the invention achieves a depletion of alkaline earth and heavier metal cations, thus reducing water hardness. By lowering the pH value through the exchange of cations with protons, the solubility of the downstream magnesium salt is increased, ensuring that a sufficient amount of magnesium ions reliably enters the water stream.

[0028] All lines and the raw water inlet of a filter device according to the invention can be designed as flexible or rigid lines made of suitable materials or material mixtures. It is also possible for device units to be connected to one another by direct connection, with the respective filter media always being spatially separated in filter elements that may be directly adjacent to one another. The direct connection of device units offers the particular advantage of a more compact design of a filter device according to the invention.

[0029] Further advantages, embodiments, and possible applications of the invention will become apparent from the following description of the drawings and examples. All described and / or illustrated features, individually or in any combination, constitute the subject matter of the invention, regardless of their inclusion in the claims or their reference to them. Fig. 1 Schematically simplified, a first possible embodiment of the filter device according to the invention, Fig. 2 schematically simplified a second possible embodiment of the filter device according to the invention, in which a separating device is arranged downstream of the first filter element and upstream of the second filter element, Fig. 3 schematically shows a third possible embodiment of the filter device according to the invention, in which at least one further filter element is connected upstream of the water outlet and Fig. 4 schematically simplifies a fourth embodiment of the filter device according to the invention, which has two separating devices, wherein the first separating device is connected upstream of a first filter element and the second separating device is connected upstream of the second filter element.

[0030] The Fig. The filter device 100 according to the invention shown in Figure 1 represents a first possible embodiment, based on which the basic principle of the invention will be described in more detail. Here, raw water is first fed to a separating device 110 via a raw water inlet 111. In the separating device 110, the supplied raw water stream is divided into two partial streams, with a first partial stream being passed through a first line 112 and a second partial stream being passed through a second line 113. The first partial stream is passed into a first filter element 120, which contains an ion exchanger. The ion exchanger can preferably be an acidic ion exchange material.

[0031] In the first filter element 120, a pretreated partial water stream is thus obtained, which is fed via a line 121 to a second filter element 130, in which a mixture of at least one magnesium salt and a water-insoluble solid is provided as filter material.

[0032] The at least one magnesium salt can be magnesium silicate, magnesium carbonate, magnesium oxide, magnesium hydroxide, a magnesium phosphate, or a mixture thereof. In a preferred embodiment, the water-insoluble solid contains activated carbon.

[0033] In this way, water flowing through filter element 130 absorbs magnesium ions. In addition to line 121, line 113 also flows into the second filter element 130, so that water from the separator 110 can also be fed directly.

[0034] Finally, an at least partially treated water stream is received and discharged via a water outlet 131.

[0035] Fig. Figure 2 shows a second embodiment of the filter device 200 according to the invention, in which a separating device 210 is arranged downstream of a first filter element 220 and upstream of a second filter element 230. Thus, only a first partial flow is conducted via line 211 into the second filter element, and a second partial flow is conducted via a second line 212 past the second filter element directly into a water outlet 231.

[0036] The Fig. The filter device 300 shown in Figure 3 extends the filter device according to the invention by at least one further filter element 332, which can be arranged upstream or downstream of the other device units as desired.

[0037] The Fig.The filter device 400 according to the invention shown in Figure 4 differs from the previously described embodiments in that it has two separating devices 410, 410', wherein the first separating device 410' is arranged upstream of a first filter element 420, while the second filter device 410" is arranged downstream of the first filter element 420 and upstream of the second filter element 430. List of reference symbols 100 filter device 111 Raw water inlet 112, 113 Line 110 Separator 120 first filter element 121 Line 130 second filter element 131 Water drain 200 filter device 211 Raw water inlet 220 first filter element 221 line 210 Separator 211, 212 line 230 second filter element 231 Water drain 300 filter device 311 Raw water inlet 310 separating device 312, 313 line 320 first filter element 321 line 330 second filter element 331 line 332 additional filter element 333 Water drain 400 filter device 411 Raw water inlet 410' first separator 412', 413' line 420 first filter element 411" line 410" second separator 412", 413" line 430 second filter element 431 line QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited Patent Literature

[0000] EP 2 094 611 B2

[0007] US 4,732,674 A

[0008] EP 1 370 338 A2

[0009] EP 1 253 114 A2

[0010] EP 3 034 145 A1

[0011]

Claims

[1] Filter device for at least partial treatment of raw water, comprising a raw water inlet, two filter elements connected in series and a downstream water outlet, wherein the first filter element contains an ion exchanger and the second filter element contains a mixture of at least one magnesium salt and a water-insoluble solid, characterized by that at least one separating device is provided for dividing a water flow into two partial flows, of which only one partial flow is passed over the first and / or the second filter element. [2] Filter device according to claim 1, characterized by that the first and the second filter element are provided in a common cartridge which can be inserted into the filter device, or that the first and the second filter element are provided in two cartridges which can be inserted separately into the filter device. [3] Filter device according to claim 1 or 2, characterized by that the separating device is arranged upstream of the first filter element and the partial flow passed through the first filter element is passed completely through the second filter element or that the separating device is arranged downstream of the first filter element and upstream of the second filter element. [4] Filter device according to claim 1 or 2, characterized by that two separating devices are provided, the first of which is connected upstream of the first filter element and the second of which is connected downstream of the first filter element and upstream of the second filter element. [5] Filter device according to one of the preceding claims, characterized by that the ratio of the partial flows can be adjusted via at least one valve. [6] Filter device according to one of the preceding claims, characterized bythat at least one measuring device is provided for recording the total quantity and the partial flows. [7] Filter device according to one of the preceding claims, characterized by that at least one further filter element is provided upstream of the water drain. [8] Filter device according to one of the preceding claims, characterized by that the at least one magnesium salt and / or the water-insoluble solid are present as at least two separate granules or as one granule. [9] Filter device according to one of the preceding claims, characterized by that the at least one magnesium salt is magnesium silicate, magnesium carbonate, magnesium oxide, magnesium hydroxide, a magnesium phosphate, or a mixture of the foregoing, preferably magnesium carbonate, magnesium hydroxide, magnesium oxide and / or the water-insoluble solid contains at least partially activated carbon. [10] Filter device according to one of the preceding claims characterized by that the ion exchanger contains an acidic ion exchange material.

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