System and dosing unit for dosing calcium hypochlorite into a water system

Abstract

System for dosing calcium hypochlorite into a water system, in particular into swimming pool water, comprising a mixing system (M) in which an aqueous calcium hypochlorite solution or suspension is produced by adding a solid composition containing calcium hypochlorite to process water, and a dosing device (5) for the dosed introduction of the aqueous calcium hypochlorite solution or suspension into the water system, characterized in that the process water, before the addition of the composition, is passed through a container (4) or a flow-through fitting containing granules of a medium which causes catalytic precipitation of hardness-forming ions dissolved in the process water by forming seed crystals, in particular calcium carbonate and / or magnesium carbonate crystals.

Description

[0001] The invention relates to a system and a dosing system for dosing calcium hypochlorite into a water system, according to the preambles of independent claims 1 and 9.

[0002] DE 10 2020 108 167 B4 discloses a dosing and mixing system for producing a chlorine-containing solution or suspension from a chlorine-containing, free-flowing solid, which may in particular be calcium hypochlorite granules. The known dosing and mixing system comprises a mixing tank with a water inlet and a material inlet for the free-flowing solid, through which, in particular, calcium hypochlorite granules can be fed into the mixing tank and converted into an aqueous solution or suspension with water introduced via the water inlet. The chlorine-containing aqueous solution or suspension produced in this way can then be fed to a water system, for example, swimming pool water, for treatment and in particular for disinfection and sterilization of the water.Depending on the solubility of the solid added to the process water, an aqueous solution or suspension of the solid is formed in the mixing tank. If calcium hypochlorite is used as the solid, an aqueous solution or suspension of calcium hypochlorite is formed in the process water, depending on the solubility of the calcium hypochlorite composition used. The solubility of the added calcium hypochlorite granules depends on the composition of the calcium hypochlorite-containing solid.

[0003] Calcium hypochlorite compositions that can be used for water treatment, such as disinfecting and sterilizing swimming pool water, are known from the state of the art. Known calcium hypochlorite compositions contain up to 10 wt.% lime (calcium carbonate) in addition to calcium hypochlorite. This lime content can prolong the release time of chlorine from the calcium hypochlorite into the process water. However, the addition of lime to calcium hypochlorite compositions causes considerable problems when calcium hypochlorite compositions are used in dosing and mixing systems for converting calcium hypochlorite into an aqueous solution or suspension. In particular, the high levels of lime added and the resulting excess calcium in the aqueous solutions or suspensions can lead to precipitation of poorly soluble calcium compounds, such as calcium carbonate (lime), calcium sulfate (gypsum), or calcium hydroxide.Such undissolved or poorly soluble calcium compounds in the aqueous solution or suspension can lead to malfunctions in the dosing and mixing system, as the undissolved particles of these calcium compounds can clog the pipes or conveying equipment of the dosing and mixing system, such as pumps. These blockages in pipes or other components of the dosing and mixing system result in dosing interruptions. This leads to inadequate disinfection of the treated water and, on the other hand, requires considerable effort to eliminate the dosing interruptions and the blockages in the dosing and mixing system.

[0004] Blockages in the dosing and mixing system can occur, particularly if the calcium hypochlorite compositions used to produce the aqueous chlorine solution or suspension are of poor quality. Poor quality calcium hypochlorite compositions are indicated, for example, by a low active chlorine content in the produced solution or suspension (with the same amount of calcium hypochlorite composition used) and a high content of water-insoluble calcium hydroxide (Ca(OH)2) and lime (Ca(CO3)) in the composition. Foreign substances such as abraded material from the manufacturing process, additives, or sand may also be present in the solution or suspension.

[0005] The poor quality of calcium hypochlorite compositions increases material consumption on the one hand and, on the other hand, leads to the formation of chlorine sludge, which settles and accumulates, particularly at the bottom of the mixing tank in which the aqueous solution or suspension is produced, as well as in dosing lines and components such as check valves or injection points. The chlorine sludge is kept suspended during solution production, e.g., by an agitator arranged in the suspension tank. When the solution or suspension is mixed into a volume flow of the water system, e.g., via a bypass, a delayed precipitation of chlorine sludge can occur, particularly due to an abrupt change in the pH value in the solution / suspension when introduced into the water system.

[0006] To eliminate undissolved or poorly soluble calcium compounds in calcium hypochlorite solutions or suspensions, DE 10 2006 045 109 A1 proposes dissolving the undissolved or poorly soluble calcium compounds by adding acids, such as hydrochloric acid. However, this is harmful to the environment and poses a health risk to the personnel operating the dosing and mixing system. Furthermore, according to DIN 19643-1:2023-06, No. 11.1, mixing acidic pH correction agents with calcium hypochlorite or sodium hypochlorite solution should be strictly avoided due to the release of chlorine gas.

[0007] DE 10 2013 111 150 A1 discloses an aqueous suspension of calcium hypochlorite with an additive comprising a complexing agent selected from the group of polyphosphates, phosphonates, and / or polycarboxylates, water, and optionally a base. The additive achieves essentially complete dispersion of the solid calcium hypochlorite particles and the water-insoluble accompanying substances in the suspension.

[0008] The disadvantage of using such additives for addition to a calcium hypochlorite composition or an aqueous solution thereof is the associated additional effort for dosing the additives, the associated challenge of ensuring the correct dosing quantity, as well as the additional operating resources (additives and dosing devices) that must be used for this purpose, with the necessary approval for bathing water treatment.

[0009] When using calcium hypochlorite compositions of inadequate quality, it has been observed that insoluble or poorly soluble calcium compounds form deposits in the form of plates on the walls of the mixing tank or other containers, as well as on the walls of dosing / pipes of a dosing and mixing system. These plates can flake off from the walls during operation of the dosing and mixing system, and the flaked plates can cause damage or blockages in the pumps or other components of the system. In addition to the formation of plates, clogging of pipes and injection points has been observed.

[0010] Particularly serious problems with blockages in pipes and components of a dosing and mixing system for producing and dosing a calcium hypochlorite solution or suspension into a water system can arise if the calcium hypochlorite granules used to convert the aqueous solution or suspension contain a high dust content and, in particular, a large number of calcium hypochlorite particles with a particle diameter of < 150 µm. In such cases, the solubility of the calcium hypochlorite granules proves to be insufficient, resulting in frequent blockages.To prevent such blockages, which are caused by a high dust content in the grain size distribution of the calcium hypochlorite granules used, filters are often integrated into the dosing and mixing systems. However, these filters reach their limits at very high dust contents because the filters used are unable to filter out the small dust particles in the calcium hypochlorite granules with diameters of < 150 µm. Such problems with a high dust content in the calcium hypochlorite granules arise particularly when the grain size distribution of the calcium hypochlorite granules contains more than 0.5% and especially more than 1% of particles with a diameter of < 150 µm. Such high dust contents in the calcium hypochlorite granules can be removed from the calcium hypochlorite granules using other separation mechanisms, such as cyclone separators, in addition to or instead of filters.However, the integration of such separation devices into dosing and mixing systems increases both the production costs and the operating costs of the dosing and mixing system.

[0011] Against this background, the invention is based on the object of providing a system and a dosing system for dosing calcium hypochlorite into a water system, which ensure improved solubility of the calcium hypochlorite solid in an aqueous solution or suspension in a cost-effective, environmentally friendly, and long-lasting manner, thereby preventing blockages in a dosing and mixing system in which the aqueous calcium hypochlorite solution or suspension is prepared and with which the chlorine-containing solution or suspension is added to a water system. Improved solubility is to be achieved, particularly when using lower-quality calcium hypochlorite compositions with a high impurity and dust content. Furthermore, occupational safety is to be improved, and as few operating and dosing media as possible are to be used.

[0012] This object is achieved with the system of claim 1 and with a dosing system having the features of claim 9. Preferred embodiments of the system and the dosing system are defined in the dependent claims.

[0013] In the system according to the invention, which comprises a mixing system and a dosing device for the metered introduction of an aqueous calcium hypochlorite solution or suspension into the water system, an aqueous solution or suspension is generated in the mixing system by adding a solid composition containing calcium hypochlorite to process water, and the aqueous solution or suspension is then metered into the water system by means of the dosing device. According to the invention, before the composition is added, the process water is passed through a container containing granules of a medium that catalytically precipitate hardness-forming ions dissolved in the process water by forming seed crystals, in particular calcium carbonate and / or magnesium carbonate crystals.

[0014] Instead of a container at least partially filled with the granules of the medium, a flow-through fitting at least partially filled with the granules of the medium can also be provided. This flow-through fitting is arranged, in particular, in a water inlet that serves to feed the process water into a mixing tank in which the calcium hypochlorite-containing composition is converted into a calcium hypochlorite solution or suspension in the process water. When reference is made below to the container at least partially filled with the granules of the medium, this also includes the flow-through fitting.

[0015] The formation of seed crystals causes the hardness-forming substances contained in the process water, particularly calcium carbonate and / or magnesium carbonate, to precipitate as it passes through the tank. If the process water passing through the tank is water from the water system that is to be treated and disinfected with the system by adding calcium hypochlorite, this process water contains a significant excess of calcium ions due to previous disinfection with a calcium hypochlorite solution or suspension. Therefore, calcium carbonate is the primary precipitant in the process water.

[0016] It has surprisingly been shown that the formation of seed crystals by catalytic precipitation of hardness-forming ions from the process water, in particular calcium carbonate and / or magnesium carbonate crystals on the surface of granulate particles of the medium, which, after reaching a certain size, detach from the granulate particles of the medium and are carried out with the process water flowing through the container, improves the solubility of the calcium hypochlorite composition subsequently added to the thus pretreated process water.

[0017] Furthermore, the properties of the resulting chlorine sludge are improved, significantly reducing the tendency to clog. This allows precipitates to be controlled and flushed out hydromechanically, and significantly extends the service life of the systems.

[0018] This prevents or at least reduces blockages in a dosing system, where the calcium hypochlorite solution or suspension is produced in a mixing tank and then fed into the water system, thus avoiding interruptions in a continuous dosing process. Improving the solubility of the solid calcium hypochlorite composition in the process water also improves the efficiency of water disinfection because a higher proportion of the chlorine from the calcium hypochlorite composition in the solution or suspension is available as active chlorine for disinfection. Furthermore, greater (storage) stability of the prepared solution or suspension is achieved, resulting in increased efficiency and reduced chlorate formation.

[0019] Furthermore, the formation of chlorine sludge, which settles particularly in the mixing tank of a dosing system at the bottom of the tank or in other components of the dosing system, can be influenced in such a way that a conversion to calcite and / or portlandite occurs. This conversion reduces blockages, particularly in the system's pipes, caused by the formed chlorine sludge. This can extend the intervals between cleaning processes required to clean the dosing system and, in particular, to remove chlorine sludge. In particular, the formation of plate-like deposits on the walls of the mixing tank of a dosing system, which can then flake off during operation and cause damage and blockages in the pumps, pipes, and components of the dosing system, can be largely prevented by pretreating the process water in the tank filled with granules of the medium.This can extend the service life of the dosing system and the pumps used to pump the process water and the produced calcium hypochlorite solution or suspension.

[0020] Due to the precipitation of the hardness-forming agents contained in the process water, particularly calcium and carbonate ions, into calcium carbonate crystals, the calcium in the pretreated process water is present in a bound form and therefore apparently and surprisingly does not lead to the formation of conventional chlorine sludge. The chlorine sludge precipitates in the process water pretreatment according to the invention are in a calcite form, which is less prone to clogging and adhesion to the walls and pipes of the plant.

[0021] Media such as those used in the system according to the invention for the catalytic precipitation of the hardness-forming agents contained in the process water, which are introduced in granular form into the container through which the process water is passed before the addition of the calcium hypochlorite composition, as well as systems for their production, are known from the prior art, for example from EP 0 957 066 B1 and EP 3 581 273 A1. These media are used to prevent limescale deposits in water-carrying systems, pipelines, and hot water heaters. The active principle underlying the mechanism of seed crystal formation is also referred to and explained in the literature using the terms “template assisted crystallization” (TAC) or “nucleation assisted crystallization” (NAC), such as in WO 2023 / 205558 A1, EP 3 888 775 B1, EP 3 500 532 B1 and WO 2021 / 155110 A1.

[0022] These media, also known as "TAC media," which are particularly available in granular form with small particles, especially spheres with diameters in the range of 100 µm to 2 mm, produce seed crystals on the particularly porous surface of the granule particles due to a catalytic effect of the medium upon contact with water in which hardness-forming ions such as calcium and / or magnesium ions as well as carbonate and / or bicarbonate ions are dissolved. This results in the formation of seed crystals on the particularly porous surface of the granule particles due to a catalytically triggered recombination of the hardness-forming ions, for example to form calcium carbonate and / or magnesium carbonate crystals. The seed crystals formed on the surface of the granule particles continue to grow up to a certain size and then detach from the surface of the granule particles, taking on the crystalline form of, for example, calcite or portlandite, with the property of not accumulating on surfaces as limestone.The seed crystals formed can therefore be washed out with the water stream that is passed through the granules of the medium.

[0023] In the system according to the invention, during the pretreatment of the process water in the container at least partially filled with the granules of the medium, the calcium contained in the process water is bound in the calcium carbonate seed crystals due to the formation of the seed crystals, and further calcium ions, particularly those present in excess in the process water, can be bound in the form of calcium carbonate to the seed crystals in the process water, which serve as nucleation sites for further crystal growth. In particular, further calcium carbonate and / or magnesium carbonate crystals can attach to or grow on the seed crystals detached from the surface of the granule particles of the medium. This binding of the calcium ions, particularly those present in excess in the process water, apparently and surprisingly influences the formation of chlorine sludge and improves the solubility of calcium hypochlorite in the pretreated process water.The chlorine sludge formed is no longer in the usual form but in a calcite form or another crystal form or crystal modification that is less prone to adhesion to surfaces, thus preventing blockages in the pipes of the dosing and mixing system and the formation of plate-like deposits.

[0024] The seed crystals that form in the tank are flushed out with the process water and can exert a depot effect in the process water because they serve as a nucleation site for the further deposition of hardness-forming crystals, particularly calcium carbonate and magnesium carbonate crystals. They can bind the hardness-forming agents in the process water in multiple seed crystals, exerting a depot effect that then, in turn, binds the many times higher amount of calcium ions introduced by the calcium hypochlorite composition, thus binding the entire amount of hardness-forming agents (especially calcium ions) contained in the process water in the form of crystals.The ions bound in crystals are then apparently no longer available for the formation of chlorine sludge in the conventional, difficult-to-remove form, but a different form of chlorine sludge is formed (namely in a calcite form or another crystal modification), which does not, or at least to a lesser extent, lead to adhesion to surfaces and therefore avoids blockages.

[0025] In the system according to the invention, the process water is preferably passed through the container in a water stream at a predetermined flow rate. The water stream can be passed through the container continuously or discontinuously (i.e., batchwise). This enables the seed crystals formed in the container by catalytic precipitation to initially detach more easily from the granulate particles of the medium and then to be flushed out with the water stream of the process water flowing through the container. The seed crystals flushed out with the process water can thus optimally develop their depot effect because they are available as a nucleation site for the further deposition of crystals, in particular calcium carbonate and magnesium carbonate crystals, in the process water that has been passed through the container.In this way, the entire amount of hardness-forming agents, especially calcium ions, contained in the process water can be bound in the form of crystals. This is particularly advantageous when the process water is water from the water system, which has a high excess of calcium ions compared to other hardness-forming cations. This is because the very high excess of calcium ions introduced by the calcium hypochlorite composition is bound by the seed crystals previously formed in the process water, preventing or at least delaying the precipitation as limestone, which cannot be removed or washed out.

[0026] The enriched calcium content of the process water is actually beneficial, as it increases the number of seed crystals formed and thus the depot effect in the process water. To utilize this effect even when the process water used is soft water (e.g., soft water from the public drinking water supply), the process water used is first hardened before being fed to the pretreatment in the tank containing the medium.

[0027] Dosing systems typically feature automatic or manually controlled flushing devices for dosing lines, components, and injection points. Flushing with process water not only provides a hydromechanical flushing effect, but also a chemical effect by introducing additional seed crystals. These crystals bind other hardness-forming agents in the lines or chemically dissolve and remove existing deposits.

[0028] When the calcium hypochlorite solution or suspension is mixed into the water system using a Venturi process, the motive water used in this process also comes into contact with the seed crystals. When the solution or suspension is mixed into a bypass of the water system, for example, using a jet pump and subsequent piping with a Venturi nozzle, a further depot effect is available if the solubility product changes and limescale precipitation occurs again.

[0029] To ensure the most even distribution possible of the seed crystals formed in the container and their efficient discharge with the process water flow, it is advantageous if the granules of the medium in the container are fluidized by introducing the process water. This can be achieved, for example, by only partially filling the specified filling volume of the container with the granules of the medium, e.g., in a range of 10% to 70%, preferably 15% to 50%, and in particular between 18% and 30% of the container volume.

[0030] In a preferred process, the process water is taken from the water system. This has advantages in terms of the pH value already established by the water system, which is preferably in the range of 7.2 to 7.8, as well as the increase in the solubility product. The resulting disadvantages, such as supersaturation of the process water taken from the water system with calcium ions (and possibly also with magnesium ions) and the associated water hardness of the process water, are not only compensated for by the inventive pretreatment of the process water in the tank to precipitate the hardness-forming calcium and magnesium ions, but are even beneficial due to the increased formation of seed crystals and the resulting depot effect, preventing blockages and the formation of chlorine sludge deposits.

[0031] As an alternative to this preferred process, drinking water, e.g., from a drinking water supply, or industrial water, e.g., from a industrial water reservoir, can also be used as process water. The water used as process water, especially in soft water areas, is appropriately hardened before passing through the tank containing the medium to generate a high quantity of seed crystals and thereby achieve a sufficient depot effect of the seed crystals in the process water.

[0032] The aqueous solution or suspension is preferably produced in a mixing tank of a dosing and mixing system, with the process water being fed to the mixing tank via a water inlet and the solid calcium hypochlorite composition being fed through a composition inlet. A stream of process water at a predetermined flow rate, preferably in the range of 20 to 55 liters per minute, is fed into the mixing tank via the water inlet, and an amount of the composition, preferably between 2 and 80 grams per liter of process water, adapted to the flow rate or volume of the mixing tank, is fed into the process water via the composition inlet. This enables optimal dosing by material-saving adaptation of the supplied amount of calcium hypochlorite composition to the required dosage and the amount of aqueous calcium hypochlorite solution or suspension required per unit of time.For example, the dosage required for disinfecting swimming pool water ranges from 2 to 80 grams of calcium hypochlorite composition per liter of process water.

[0033] The dosing system according to the invention comprises a mixing tank for producing an aqueous calcium hypochlorite solution or suspension by adding a solid composition containing calcium hypochlorite to process water. The mixing tank has a water inlet for supplying the process water and a composition inlet for adding the calcium hypochlorite composition to the process water. For pretreating the process water, in particular according to the method, a tank containing granules of a medium is arranged in the water inlet. The medium causes catalytic precipitation of hardness-forming ions dissolved in the process water by forming seed crystals, in particular calcium carbonate and / or magnesium carbonate crystals, in the process water introduced into the tank through the water inlet.

[0034] In a preferred embodiment of the dosing system, the container, which is particularly designed as a pressure vessel, has a predetermined container volume, which is preferably in the range of 5 liters to 50 liters and particularly preferably between 10 liters and 40 liters. To enable fluidization of the granules of the medium when the process water is introduced into the container, only a portion of the container volume, for example, 5% to 70%, preferably 10% to 50%, and in particular between 10% and 30% of the container volume, is filled with the granules of the medium. This enables complete fluidization of the granules of the medium in the process water.At the same time, the process water flow, which flows through the tank at a predetermined flow rate, promotes the detachment of the seed crystals from the surface of the medium's granulate particles, and the detached seed crystals are efficiently flushed out of the tank with the water flow. Fluidization is improved at a smaller fill level, for example, 50% of the tank volume or less. However, at very small fill levels of less than 10% of the tank volume, the amount of medium in the tank is too small to generate a sufficient number or concentration of seed crystals in the process water to bind the high proportion of calcium ions in the process water into crystals.Therefore, preferably a proportion of the container volume of 10% to 70%, in particular of 10% to 50% and particularly preferably of 10% to 30% and in particular between 15% and 30% of the container volume is filled with the granules of the medium.

[0035] The process water is expediently fed into the tank through an inlet (inlet) connected to the water inlet and discharged from the tank through an outlet (outlet) connected to the mixing tank. The process water flows through the tank, preferably against gravity, from bottom to top. This promotes fluidization of the medium granules within the tank volume, ensuring homogeneous mixing of the formed seed crystals throughout the tank volume and efficient removal of the seed crystals that have detached from the surface of the medium granules from the tank via the flow of process water.

[0036] The process water preferably has a minimum content of hardness-forming agents in order to be able to produce a sufficient quantity of seed crystals. The more hardness-forming agents there are in the process water - assuming a sufficient quantity of granulate of the medium in the tank - the more seed crystals can be produced and the greater the depot effect. The water in the water system that has already been disinfected with the calcium hypochlorite solution or suspension is therefore particularly suitable due to its high Ca content (enrichment of Ca ions via the addition of the calcium hypochlorite composition). Optimization can be achieved through targeted hardening (i.e., increasing the total / carbonate hardness of the process water), which is particularly the case when using drinking water from the public drinking water supply in soft water regions.

[0037] The medium, which is filled into the container in granular form, is, for example, a polymer, in particular polyacrylate or polystyrene. Specifically, the medium is a granular, modified ion exchange material, in particular a weakly acidic ion exchange material, in which a carboxylate group of the ion exchange material is reacted with cations of sparingly soluble salts, in particular with Ca 2+ - ions and / or Mg 2+ - ions. The ion exchange material is then in the cation form, e.g. in the Ca 2+ -form. Due to the electrostatic and stereochemical properties of the modified ion exchange material, this conditioning of the ion exchange material allows calcium and magnesium ions, as well as carbonate ions, to recombine on the surface of the granulate particles to form calcium and / or magnesium carbonate through a catalytic reaction, thereby forming seed crystals.

[0038] The granules of the medium in particular comprise granules with a particle size distribution in which more than 66% of the granules have a diameter between 0.5 mm and 1.5 mm and / or in which the average particle size is between 0.5 mm and 1.5 mm. In order to retain the granules in the container, a filter with a mesh size adapted to the size of the granule particles of the medium is therefore preferably arranged, in particular downstream of the container in the water inlet and / or at an outlet of the container. A filter sieve is preferably arranged in the water inlet, in particular downstream of the container, and / or at an outlet of the container, wherein the filter sieve retains particles with a diameter of more than 0.1 mm or preferably more than 0.2 mm in the container.

[0039] To be able to direct water from the water system via the tank into the mixing tank of the dosing system as process water, the water inlet is preferably connected to the water system. This allows water from the water system to be fed into the dosing system for treatment as process water.

[0040] The dosing system conveniently contains a withdrawal device with a supply line, with which the solution or suspension produced in the mixing container can be fed into the water system via the supply line in order to disinfect the water contained therein with the chlorine-containing solution or suspension.

[0041] In the system and dosing device according to the invention, the conversion of the hardness formers in the process water by means of seed crystal formation, which is known from the prior art, is not primarily used, but rather a secondary effect of the seed crystals, which, when a calcium hypochlorite composition is added to the process water, binds the massive Ca 2+ -excess to the already formed seed crystals. Due to the manufacturing process, when a solution or suspension is prepared by adding a calcium hypochlorite composition to water, large amounts of calcium ions and very large amounts of calcium carbonate (lime) are introduced into the aqueous solution or suspension. These unavoidable additives are present due to the calcium hypochlorite production process.

[0042] The pretreatment of the process water according to the invention creates a depot effect by creating an additional capacity in the process water (in addition to the absorption capacity of the water within the scope of the solubility product) through the formation of seed crystals, which is able to bind the hardness excessively introduced via the dosed addition of the calcium hypochlorite composition (in particular with regard to carbonate ions and calcium ions, which have a concentration 5 - 50 times higher than in the process water used) in crystals (in particular calcium carbonate crystals).

[0043] The greater the number of seed crystals formed, the greater the binding effect. The advantage of this effect is particularly noticeable when water from the water system that has already been disinfected with the calcium hypochlorite solution or suspension is used as process water, since this water already contains an excess of Ca ions. If necessary, the (depot) effect can be enhanced by further hardening the process water. This is particularly advantageous when (soft) drinking water from the public drinking water supply is used as process water.

[0044] Due to the very high concentration of calcium ions in the process water, the seed crystals on the granulate particles of the medium can grow to such a size that precipitation is unavoidable. The altered crystal structure of the precipitates resulting from the addition of the calcium hypochlorite composition to the process water means that they no longer tend to adhere and grow in the pipes and on the tank walls of the dosing system, thus preventing blockages in the system and its components.

[0045] The effect is further improved if, in addition to the use of seed crystals, further measures are taken to hydromechanically remove the precipitates. While dosing of the calcium hypochlorite solution or suspension via a Venturi nozzle directly mixes the solution or suspension into the motive water of the water system, dosing via peristaltic pumps results in concentrated transport via sometimes very long dosing lines with small diameters. In both variants, rinsing with the process water pretreated in accordance with the invention is preferably carried out automatically or manually at rinsing intervals on the system side, which creates an additional effect because the seed crystals present in the process water prevent deposits.

[0046] These and other advantages, as well as useful and preferred features of the invention, will become apparent from the exemplary embodiments described below with reference to the drawings, which each show, by way of example only, preferred embodiments of the dosing system according to the invention and the system according to the invention for dosing calcium hypochlorite into a water system. In the drawings: Fig. 1: Schematic representation of a system for treating water from a water system with a dosing system according to the invention of a first embodiment; Fig. 2: Schematic representation of a system for treating water from a water system with a dosing system according to the invention of a second embodiment; Fig. 3 Sectional view of a container filled with a granulate of a medium, which is used in the dosing systems of the Fig. 1 and Fig. 2 is used.

[0047] In Fig. 1 shows a system for treating water from a water system with a first embodiment of a dosing system for dosing calcium hypochlorite into the water system. The dosing system serves to produce and dose an aqueous calcium hypochlorite solution or suspension and to feed the solution or suspension into the water system and for this purpose comprises a mixing system M and a dosing device 5. The water system can, for example, be, as in the example of Fig. 1, a swimming pool 10 filled with bathing water is shown. The swimming pool 10 is connected to a raw water tank 12 via a drain line 11. The raw water tank 12 has a fill water connection 13 for filling and refilling water, in particular service or drinking water. The fill water connection 13 can, for example, be connected to a drinking water line. To introduce water from the raw water tank 12 into the swimming pool 10, an inlet line 16 is connected to the raw water tank 12 and the swimming pool 10. A circulation pump 14 for pumping the water from the raw water tank 12 into the swimming pool 10 is arranged in the inlet line 16. Furthermore, a filter system 15 is arranged in the inlet line 16 to filter the water introduced into the swimming pool 10.

[0048] To treat the water from the raw water tank 12, the Fig. 1 Dosing system, labeled D, is integrated into the water cycle. Filtrate (i.e., water taken between the filter and the disinfection injection point) is used as process water.

[0049] The dosing system D comprises a mixing system M with a mixing container 1, which is connected to the inlet line 16 via a water inlet 2, and a dosing device 5 with a supply line 6 for supplying a calcium hypochlorite solution or suspension S produced in the mixing system M into the inlet line 16. To convey the calcium hypochlorite solution or suspension S into the inlet line 16, the dosing device 5 comprises a pump 9 (e.g., a jet pump and / or one or more peristaltic pumps), which sucks the solution or suspension from the mixing container 1. Details and further features of the dosing and mixing system can be found in patent specification DE 10 2020 108 167 B4, which is incorporated herein by reference.

[0050] A valve for opening and closing the water inlet 2 is provided in the water inlet 2. Furthermore, a motive water pump 8 is arranged in the water inlet 2, with which process water can be pumped from the inlet line 16 into the mixing tank 1 of the mixing system M and, if necessary, the jet pump 9 can be operated.

[0051] Furthermore, a container 4 is arranged in the water inlet 2, in which a granulate of a medium is contained, which causes a catalytic precipitation of the hardness-forming ions dissolved in the process water introduced into the container 4 through the water inlet 2 by forming seed crystals.

[0052] The following commercially available products can be contained, for example, as a medium in granulate form in container 4: Limescale protection Maicat® from Woegerbauer, AquonPure® from AQON Water Solutions, BIOCAT® KLS from Watercryst, EagleSorb® ES3 Anti-Scale, OneFlow®, Next-ScaleStop™ or Filtersorb® SP3 from WatchWater.

[0053] The mixing tank 1 of the mixing system M further contains a composition inlet 3 for adding a composition containing calcium hypochlorite. The calcium hypochlorite composition is preferably in powder or granular form and stored in a composition tank 7. The composition tank 7 can, for example, be a container containing calcium hypochlorite granules.

[0054] To produce an aqueous calcium hypochlorite solution or suspension, a stream of process water is fed via water inlet 2 at a preferred flow rate of, for example, 40 to 55 liters per minute through tank 4 into mixing tank 1. Simultaneously or subsequently, the calcium hypochlorite composition is sucked from composition tank 7 via a suction device and fed via composition inlet 3 into mixing tank 1 and introduced into the process water contained therein. The calcium hypochlorite composition is added to the process water at a predetermined dosage, for example, in a dose of 2 grams per liter to 20 grams per liter of process water. In mixing tank 1, the calcium hypochlorite composition is added to the process water and converted to an aqueous calcium hypochlorite suspension, preferably dissolved by means of an agitator.In this way, a solution or suspension of calcium hypochlorite in water in a defined concentration is produced in the mixing container 1.

[0055] Using the dosing device 5 of the dosing system D, the calcium hypochlorite solution or suspension can be fed from the mixing tank 1 into the feed line 16. For this purpose, the solution or suspension is sucked from the mixing tank 1 using the pump 9 (jet pump) and transferred via the feed line 6 into the feed line 16. For this purpose, the feed line 6 opens into the feed line 16 at a so-called injection point with a check valve. When using peristaltic pumps, the suspension can also be dosed directly from the mixing tank 1.

[0056] In the inlet line 16, a heating device is preferably provided for heating the process water, which can be designed, for example, as a heat exchanger 17.

[0057] In the swimming pool 10, a further drain line 20 is expediently provided, which is connected to a measuring and control system 18. A pump 19 is provided in the further drain line 20 for pumping water from the swimming pool 10 into the measuring and control system 18. The measuring and control system 18 serves to analyze the water from the water system (swimming pool 10). The measuring and control system 18 is connected via a control line 21 to a control system of the mixing system M in order to transmit the current control level for regulating the target value (chlorine content) to the dosing system.

[0058] In the dosing system D, the water from the water system (swimming pool 10) is used to produce the calcium hypochlorite solution or suspension. Fig. 1, the water from the water system (swimming pool 10) is used as process water and is used in the dosing system D to produce a calcium hypochlorite solution or suspension. According to the invention, the process water used to produce the calcium hypochlorite solution or suspension is subjected to pretreatment before being introduced into the mixing tank 1 of the mixing system M. The process water is passed through the tank 4 filled with the granules of the medium via the water inlet 2. Due to catalytic precipitation, which is triggered by the granular medium in the tank 4, the hardness-forming ions dissolved in the process water are precipitated by the formation of seed crystals, in particular in the form of calcium carbonate and / or magnesium carbonate crystals. The seed crystals formed on the granule particles of the medium dissolve after a certain time orAfter reaching a certain size of the seed crystals, they detach from the surface of the granulate particles of the medium and are washed out with the water flow of the process water, which is led via the water inlet 2 through the container 4 to the mixing container 1.

[0059] There, the seed crystals formed in the process water bind the amount of hardness-forming substances (mainly Ca) that is introduced via the calcium hypochlorite composition during production and which is many times (factor 5 to 50) higher than in the process water. 2+ -ions), and convert the precipitates into a non-adherent or at least less adherent lime crystal form.

[0060] In Fig. 2 shows a system for treating water from a water system with a second embodiment of a dosing system for dosing calcium hypochlorite into the water system.

[0061] In the second embodiment of the dosing system according to the invention - unlike in the first embodiment of Fig. 1 - instead of water from the water system (swimming pool 10), drinking or service water from the filling water connection 13 is used to produce a calcium hypochlorite solution or suspension. Except for this difference and a different dosage of the calcium hypochlorite solution or suspension, the Fig. 2 shown embodiment with the embodiment of Fig. 1. In Fig. 2, the same reference numerals are used for corresponding components of the system as in Fig. 1. As far as components of the dosing system are Fig. 1 in Fig. 2 are not explicitly shown, they are not visibly integrated in the dosing system. The composition inlet 3 of the mixing system M is in the embodiment of Fig. 2 manually filled with the calcium hypochlorite composition using a suction station or a measuring cup.

[0062] In the embodiment of Fig. 2, drinking or service water from the filling water connection 13 is used as process water for the production of the calcium hypochlorite solution or suspension. For this purpose, the filling water connection 13 is connected via a system separator BA to the water inlet 2, via which the process water, e.g. drinking water from the public drinking water supply, is fed to the mixing plant M and in particular to the mixing tank 1, preferably at a flow rate of 20 to 45 liters per minute. As in the embodiment of Fig. 1 is also in the embodiment of Fig. 2 in the water inlet 2, a container 4 is arranged, which is at least partially filled with a granulate of a medium, which causes a catalytic precipitation of the hardness-forming ions by forming seed crystals in the process water introduced into the container 4 through the water inlet 2. The process water treated by the catalytic precipitation of the hardness-forming ions in the container 4 is - as in the embodiment of Fig. 1 - into the mixing tank 1 and via a filling dosing device with a composition inlet 3, a powdered or granular calcium hypochlorite composition is manually fed into the mixing tank 1 via a suction station or with a measuring cup to form a calcium hypochlorite solution or suspension. In the mixing tank, the calcium hypochlorite composition is hydromechanically dissolved by means of a turbulator, whereby a calcium hypochlorite solution or suspension, for example in a concentration of 10 to 80 grams of calcium hypochlorite per liter of process water, is produced. The solution or suspension produced in the mixing tank 1 is, as in the embodiment of Fig. 1, is conveyed into the feed line 16 by means of a dosing device 5 with a feed line 6 and a pump 9 (in particular one or more peristaltic pumps).

[0063] Since in the example of Fig. 2 If drinking or service water is used as process water for producing the calcium hypochlorite solution or suspension, the water hardness may not be sufficient depending on the quality of the drinking or service water. It is therefore advantageous if the process water is preconditioned by hardening before being introduced into tank 4, in particular to generate an excess of calcium ions. The hardening can be achieved, for example, by adding calcium carbonate.

[0064] In Fig. 3, the container 4 of the dosing system D is shown in detail in a sectional view. The container 4 comprises a pressure vessel 46, which is designed, for example, in the form of a cartridge or cartridge and is arranged replaceably in a base 48. On an upper side of the container 4, a connection and valve head 42 is inserted into an opening of the pressure vessel 46. The connection and valve head 42 comprises a vent valve 41 as well as an inlet 4a (inlet) and an outlet 4b (outlet), a downpipe 44 connected to the inlet 4a and an annular channel 43 extending around the downpipe 44 in the area of ​​the connection and valve head 42 and communicating with the outlet 4b. For connecting the container 4 in the water inlet 2 of the dosing systems D of the Fig. 1 and Fig. 2, the connection and valve head 2 is connected to the water inlet 2 in such a way that the process water for producing the calcium hypochlorite solution or suspension flows into the container 4 through the inlet 4a (inlet) and flows out of the container 4 to the mixing container 1 of the mixing device M through the outlet 4b (outlet).

[0065] At the lower end of the downpipe 44, which extends substantially over the entire height of the container volume 45, an inlet filter 49 is arranged, which is located just above the bottom of the container 4. A granulate G of the medium is filled into the container 4 at a predetermined filling height h. The filling height h of the media granulate G is preferably selected such that between 10% and 70%, particularly preferably between 10 and 30%, of the total filling volume of the container 4 (container volume 45) is filled with the granular medium.

[0066] In Fig. 3a shows the container 4 with the granulate G of the medium filled therein in a state without water flowing through it, whereby the filling level h is shown.

[0067] The process water supplied to the tank 4 via the inlet 4a for pretreatment flows through the inlet 4a into the downpipe 44 and at the lower end of the downpipe 44 from the inlet filter 49 into the granulate bed G of the medium. In Fig. 3b shows the container 4 with the granulate G of the medium filled therein in a state through which water flows. This inflow of process water fluidizes the granulate G of the medium in the container volume of the container 4, as shown in Fig. 3b. Due to the water pressure with which the process water is pumped through the inlet 4a of the container 4, the process water flows upwards in the container 4 against gravity, as shown by the arrows 47 in Fig.3b. The upwardly flowing process water flows through the annular channel 43 of the connection and valve head 2 to the outlet 4b of the container 4. A filter screen is expediently arranged in the annular channel 43, the mesh size of which is designed such that the granulate particles of the medium are retained in the container volume 45 of the container 4. The process water flowing through the annular channel 43 to the outlet 4b (outlet) of the container 4 is finally directed into the mixing container 1 via the water inlet 2 connected to the outlet 4b. 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] DE 10 2020 108 167 B4 [0002, 0049] DE 10 2006 045 109 A1

[0006] DE 10 2013 111 150 A1

[0007] EP 0 957 066 B1

[0021] EP 3 581 273 A1

[0021] WO 2023 / 205558 A1

[0021] EP 3 888 775 B1

[0021] EP 3 500 532 B1

[0021] WO 2021 / 155110 A1

[0021] Cited non-patent literature

[0000] DIN 19643-1:2023-06, No. 11.1

[0006]

Claims

[1] System for dosing calcium hypochlorite into a water system, in particular into swimming pool water, comprising a mixing plant (M) in which an aqueous calcium hypochlorite solution or suspension is prepared by adding a solid composition containing calcium hypochlorite to process water, and a dosing device (5) for the metered introduction of the aqueous calcium hypochlorite solution or suspension into the water system, characterized by that the process water, before the addition of the composition, is passed through a container (4) or a flow-through fitting in which a granulate of a medium is contained which causes a catalytic precipitation of hardness-forming ions dissolved in the process water by forming seed crystals, in particular calcium carbonate and / or magnesium carbonate crystals. [2] System according to claim 1, wherein, due to a catalytic effect of the medium, calcium and / or magnesium ions as well as carbonate and / or bicarbonate ions attach to the surface of particles of the medium to form calcium carbonate and / or magnesium carbonate crystals and act as a nucleation site for further precipitation of calcium, magnesium, carbonate and bicarbonate ions dissolved in the process water, in particular in excess, by calcium carbonate and / or magnesium carbonate crystals attaching to or growing on the seed crystals. [3] System according to claim 1 or 2, wherein the process water is passed through the container (4) or the flow fitting in a water stream with a predetermined flow rate. [4] System according to claim 3, wherein the seed crystals formed in the container or the flow fitting are carried out of the container (4) or the flow fitting with the water flow. [5] System according to one of the preceding claims, wherein the granules of the medium in the container (4) or the flow fitting are fluidized by the introduction of the process water. [6] System according to one of the preceding claims, wherein the addition of the composition to the process water takes place in a predetermined dosage, in particular in a dose of 2 grams per liter to 80 grams per liter of process water. [7] System according to one of the preceding claims, wherein the process water is taken from the water system. [8] System according to one of the preceding claims, wherein the preparation of the aqueous solution or suspension takes place in a mixing container (1) to which the process water is fed through a water inlet (2) and the solid composition is fed through a composition inlet (3), wherein a stream of process water with a predetermined flow rate, which is preferably in the range of 20 liters per minute to 55 liters per minute, is fed into the mixing container via the water inlet (2) and an amount of the composition adapted to the flow rate, which is preferably between 2 and 80 grams per liter of process water, is fed into the process water via the composition inlet (3). [9] Dosing system for dosing calcium hypochlorite into a water system, comprising a mixing container (1) for producing an aqueous solution or suspension by adding a solid composition containing calcium hypochlorite to a process water, wherein the mixing container (1) has a water inlet (2) for supplying the process water and a composition inlet (3) for adding the composition to the process water, characterized by that a container (4) or a flow-through fitting is arranged in the water inlet (2), in which a granulate of a medium is contained, wherein the medium in the process water introduced through the water inlet (2) into the container (4) or the flow-through fitting causes a catalytic precipitation of hardness-forming ions dissolved in the process water by forming seed crystals, in particular calcium carbonate and / or magnesium carbonate crystals. [10] Dosing system according to claim 9, characterized bythat the container (4) has a predetermined container volume, which is preferably in the range from 5 liters to 50 liters and particularly preferably between 10 liters and 40 liters, wherein a proportion of the container volume of 5% to 70%, preferably from 10% to 50% and in particular between 10% and 30% of the container volume is filled with the granulate of the medium. [11] Dosing system according to claim 9 or 10, characterized by that the process water is led into the container (4) or the flow fitting through an inlet (4a) connected to the water inlet (2) and is discharged from the container (4) or the flow fitting through an outlet (4b) connected to the mixing container (1), wherein the process water flows through the container (4) or the flow fitting preferably at least partially against gravity from bottom to top. [12] Dosing system according to one of claims 9 to 11, characterized bythat the medium is a polymer, in particular polyacrylate or polystyrene. [13] Dosing system according to one of claims 9 to 12, characterized by that the medium is a modified ion exchange material, in particular a weakly acidic ion exchange material, in which in particular a carboxylate group of the ion exchange material is reacted with cations of poorly soluble salts, in particular with Ca 2+ - ions and / or Mg 2+ - ions, is loaded. [14] Dosing system according to one of claims 9 to 13, characterized by that the granules of the medium have granules with a grain size distribution in which more than 66% of the granules have a diameter between 0.5 mm and 1.5 mm and / or in which the mean grain size is between 0.5 mm and 1.5 mm. [15] Dosing system according to claim 14, characterized bythat a filter is arranged in the water inlet (2), in particular downstream of the container (4) or the flow fitting, and / or at an outlet (4b) of the container (4) or the flow fitting, which filter retains the granules in the container (4). [16] Dosing system according to one of claims 9 to 14, characterized by that a filter screen is arranged in the water inlet (2), in particular downstream of the container (4) or the flow fitting and / or at an outlet (4b) of the container (4) or the flow fitting, wherein the filter screen retains particles with a diameter of more than 0.1 mm or preferably more than 0.2 mm in the container (4) or the flow fitting. [17] Dosing system according to one of claims 9 to 16, characterized by that the water inlet (2) is connected to the water system in order to direct water from the water system via the container (4) or the flow fitting into the mixing container (1) of the dosing system. [18] Dosing system according to one of claims 9 to 17, characterized by that the dosing system comprises a dosing device (5) with a supply line (6) with which the solution or suspension produced in the mixing container (1) can be fed into the water system via the supply line (6).

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