Device and method for enriching a liquid stream with a gas

Abstract

Device for enriching a liquid stream with a gas, comprising: a) a continuous mixer (28) with a connection for the liquid flow (12), a connection for the gas (14) and a withdrawal connection for the enriched liquid flow (16), and b) a device for adjusting the differential pressure between the gas and the supplied liquid flow, characterized by c) a flow restrictor arranged between the differential pressure adjustment device and the continuous mixer (28) for the gas flow supplied to the continuous mixer (28), wherein the flow restrictor is adjustable, wherein the differential pressure adjustment device between the gas and the liquid flow is designed as a differential pressure regulator (50) which regulates the gas supply pressure such that the pressure difference between the supplied liquid flow and the supplied gas is largely constant.

Description

Technical area

[0001] The present invention generally relates to a method and a device for enriching a liquid stream with a gas. It particularly relates to a method and a device for enriching a drinking water stream with carbon dioxide. When carbonation of a liquid is mentioned in the context of the present invention, this generally refers to the enrichment of the liquid with a gas. The enrichment of a liquid, in particular water, with gaseous carbon dioxide is to be considered a special case encompassed by the generally understood term. State of the art

[0002] Devices for enriching drinking water with carbon dioxide (also known as carbonation of drinking water) have been known for a long time. In most of these devices, the carbonation of the drinking water takes place in a storage tank, usually called a carbonator vessel. Carbonator vessels are equipped with sensors that are regularly maintained and replaced. Furthermore, they usually contain several solenoid valves. Maintenance costs over their lifetime are often higher than the initial purchase price. In addition, hygiene problems are common due to the number of components in the water supply system and the low flow of the storage tank itself.

[0003] Recently, however, devices have also been developed to enrich tap water in private households or restaurants with carbon dioxide using a flow-through process. In this flow-through process, carbonation takes place in a flow-through mixer that is directly connected to the drinking water pipe. Compared to classic devices with a storage tank, flow-through carbonation without a storage tank has the advantage of being significantly more compact, cost-effective, and also more hygienic. A disadvantage of flow-through carbonation, however, is that it is very complex to achieve perfect and even carbonation when pressure fluctuations in the drinking water pipe occur. Venturi and water jet nozzles have generally been used as mixing systems. In these cases, the gas only enters the water after mixing in the tap pipe.The long tap lines required cause hygiene problems and are usually subject to complex cleaning and maintenance.

[0004] A device for enriching drinking water with carbon dioxide using a continuous flow process is described, for example, in WO 2004 / 024306. This document proposes keeping the pressure in the continuous flow mixer constant by means of an overflow valve in the tap line and an additional pressure stabilizer in the continuous flow mixer itself. A flow rate valve is also arranged in the gas supply line to keep the amount of gas fed into the continuous flow mixer per unit of time constant. The control system also includes a solenoid valve in the water connection and a solenoid valve in the gas connection of the continuous flow mixer. Both solenoid valves are closed if a pressure switch in the tap line detects a pressure increase above the working pressure. This involves a relatively complex control technology whose coordination is also relatively complicated.

[0005] PCT / DE01 / 04128 generally deals with a feed component for a tubular flow mixer with sieve inserts. Understandably, this document also seems to propose regulating the gas feed pressure into the flow mixer as a function of the water pressure. A relatively complex gas pressure control valve is presented for this purpose. However, in practice, it has been shown that such regulation of the gas feed pressure as a function of the water pressure does not guarantee satisfactory carbonation in the case of strong water pressure fluctuations or small draw-off volumes.

[0006] Finally, EP 1 926 548 A1 discloses a device and a method for enriching a liquid with a gas, which are based on a continuous-flow mixer with a connection for the liquid flow, a connection for the gas, and a discharge connection for the enriched liquid flow. Furthermore, a differential pressure regulator is provided for regulating the gas pressure as a function of the liquid pressure, wherein the differential pressure regulator keeps the pressure difference between the liquid flow and the fed-in gas largely constant. Finally, a flow rate regulator is provided downstream of the continuous-flow mixer for keeping the flow rate of the liquid flow constant, largely independent of pressure fluctuations on the inlet side. If the operating conditions remain within a predetermined range during operation of this device, the device and method proposed here deliverthe proposed process achieves satisfactory to good carbonation results. However, if the operating conditions deviate from the specified range, for example because the inlet pressure in the liquid to be enriched increases, under unfavorable circumstances the gas fed to the continuous mixer can "break through" through the continuous mixer to a tapping point, resulting in "stuttering" or splashing during the tapping process. The reason for this is that the solubility of the gas in the liquid to be enriched generally depends on both the gas and the liquid pressure. If the inlet gas pressure becomes too high, the gas is no longer fully dissolved in the continuous mixer, so that the undissolved gas escapes from the continuous mixer in the form of bubbles in the liquid and subsequently from the tapping point, causing the "stuttering" or splashing phenomena mentioned above.This problem can occur particularly when the gas pressure is regulated to the inlet liquid pressure by means of a differential pressure regulator and this pressure is subject to strong fluctuations. Object of the invention

[0007] The object of the present invention is to provide a device for enriching a liquid stream with a gas that avoids the aforementioned problems. Furthermore, the object of the invention is to provide a method for enriching a liquid stream with a gas that avoids the aforementioned problems.

[0008] These objects are achieved by a device according to claim 1 and by a method according to claim 9. Advantageous embodiments are described in the subclaims. General description of the invention

[0009] A device according to the invention is provided for enriching a liquid stream (e.g., drinking water from a freshwater pipe or a storage tank) with a gas (e.g., CO2 or O2). It comprises, on the one hand, a flow mixer having (at least) one connection for the liquid stream, (at least) one connection for the gas, and a discharge connection for the enriched liquid stream. On the other hand, the device comprises a device for adjusting the differential pressure between the gas and the supplied liquid stream.

[0010] According to the invention, the device now further comprises a flow limiter for the gas flow supplied to the flow mixer, arranged between the device for adjusting the differential pressure and the flow mixer.

[0011] Surprisingly, it has been shown that a flow restrictor arranged in this way, with a suitable design, reliably prevents gas not dissolved in the liquid flow from "breaking through" to a dispensing point for the gas-enriched liquid located downstream of the continuous mixer, even under adverse operating conditions. This results in a previously unattainable level of trouble-free dispensing – especially under adverse operating conditions, which will be discussed in more detail below.

[0012] For particularly good adaptation to fluctuating operating conditions, in particular to fluctuating pressure in the liquid to be enriched with gas, the device for adjusting the differential pressure between the gas and the liquid flow is designed as a differential pressure regulator. The differential pressure regulator can be designed, in particular, as a control valve that regulates the gas feed pressure such that the pressure difference between the supplied liquid flow and the injected gas remains largely constant. Such a differential pressure regulator can, for example, comprise a mechanical actuator actuated by the liquid pressure.

[0013] Valves allow the independent adjustment of the gas pressure and the pressure in the liquid supply, whereby in addition to the respective absolute pressures, the (average) pressure difference between the gas and the liquid to be enriched is also determined by the respective valve positions. The (average) pressure difference between the gas and the liquid to be enriched, among other factors, essentially determines the result of the gas enrichment of the liquid in the continuous mixer. The ability of an operator to adjust the pressure difference therefore represents a significant improvement in the ease of use of the device according to the invention, regardless of whether the gas feed pressure is suitably regulated such that the pressure difference between the supplied liquid stream and the fed gas remains largely constant.

[0014] In a particularly preferred embodiment of the device according to the invention, the flow limiter has a nominal diameter DN of maximum 3.0, preferably of maximum 2.5 and particularly preferably of 2.0.

[0015] A nominal diameter DN of not less than 0.1, preferably not less than 0.15 and particularly preferably not less than 0.2 has proven to be an advantageous lower limit.

[0016] The flow restrictor is adjustable, e.g., by an operator of the device, particularly within the aforementioned limits. Mechanically adjustable flow restrictors are particularly advantageous. However, electromechanical adjustment, for example, is also possible and may be advantageous under certain circumstances. It has been proven that adjusting the flow restrictor—in addition to adjusting the differential pressure between the gas and the liquid being added—allows for particularly precise adjustment of the degree of enrichment of the liquid with the gas, e.g., the degree of carbonation in the case of CO2 and water.

[0017] In a particularly advantageous embodiment, the flow restrictor is designed as a throttle or orifice. In both cases, the throttle or orifice can be adjustable.

[0018] If a differential pressure regulator is actually arranged upstream of the continuous mixer in the device according to the invention, particular advantages arise if it is adjustable. As already mentioned above, adjusting the pressure difference between the gas and the liquid to be enriched allows the degree of enrichment of the liquid to be influenced.

[0019] A particularly precise adjustment of the degree of enrichment of the liquid with the gas is achieved when both the inlet pressure differential between gas and liquid and the flow restrictor are adjustable. However, the advantage of the invention, coupled with high operating convenience, is also achieved when only the flow restrictor is adjustable.

[0020] In principle, the gas feed pressure can be greater than, less than, or equal to the pressure of the liquid to be enriched. However, it has been found that the device according to the invention delivers particularly good results when the gas feed pressure into the continuous mixer is less than or equal to the pressure of the supplied liquid stream, but in particular, is less than the pressure of the supplied liquid stream.

[0021] In a preferred embodiment, the continuous mixer of a device according to the invention comprises a nozzle head and an adjoining mixing chamber. The nozzle head advantageously has a nozzle ring gap and a gas injection nozzle arranged centrally to the nozzle ring gap. In this configuration, the connection for the liquid flow is advantageously connected to the nozzle ring gap, and the connection for the gas is connected to the gas injection nozzle. If the nozzle ring gap is adjustable, the degree of enrichment of the liquid with the gas can be (additionally) influenced by changing the nozzle ring gap.

[0022] Advantageously, in a device according to the invention, the connection for the liquid flow is configured to be connected to a fresh water line, and the connection for the gas is configured to be connected to a gas supply, e.g., an external gas cylinder or one integrated into the device itself. Finally, the tap connection of the continuous mixer is connected to a tap valve.

[0023] According to a further advantageous development of the present invention, the device further comprises a flow rate regulator connected downstream of the continuous mixer (ie downstream of the continuous mixer) for keeping the flow rate of the liquid stream constant per unit of time largely independent of pressure fluctuations in its inlet, ie both in the feed line of the liquid which is to be enriched with a gas and on the outlet side of the continuous mixer.

[0024] In this particular configuration, the proposed combination of: • maintaining a constant pressure difference between the liquid flow (mainly drinking water) and the injected gas (mainly carbon dioxide) by regulating the gas feed pressure, and • By maintaining a constant flow rate of the liquid stream using a flow rate regulator downstream of the continuous mixer, a very uniform gas enrichment can be achieved without major control effort, independent of pressure fluctuations. Due to its flow rate and water flow, the device is largely maintenance-free and hygienic. In particular, the gas-enriched liquid produces a very uniform dispensing pattern. Even with strong pressure fluctuations in the liquid stream, especially during short dispensing cycles, the gas enrichment functions optimally without any readjustment. The device—like the designs and advantageous developments discussed above—is particularly suitable for household use, primarily due to its straightforward operation and maintenance characteristics.

[0025] The result of the gas enrichment can be influenced or fixedly regulated via the differential pressure between the liquid flow and the fed-in gas and / or the flow rate of the liquid flow and / or the properties of the continuous mixer, in particular the variation of the gap width in a continuous mixer with a nozzle chamber described below (e.g. according to the teaching of WO 2004 / 024306 A1).

[0026] In a preferred embodiment, the invention thus relates to a method for enriching a liquid with a gas, wherein the degree of enrichment is variable. A preferred flow regulator comprises a throttle body arranged in a flow cross-section of the flow regulator in such a way that it reduces the flow cross-section if the pressure in the liquid flowing through it increases, and increases it if the pressure in the liquid flowing through it decreases. Such a flow regulator does not require any separate sensors or a power supply. It can simply be installed in a dispensing line or a dispensing tap. A fixed or adjustable flow regulator can be used. With an adjustable flow regulator, it is also possible to influence the result of the gas enrichment by readjusting the flow rate.

[0027] The following describes exemplary concepts for the carbonation of water, i.e., the enrichment of water with dissolved CO2. These concepts can be directly applied to the enrichment of any liquid with a gas. Accordingly, the term "carbonization" used below should also be understood as an example for gas enrichment in general.

[0028] It has already been discussed above that the result of the gas enrichment, i.e., the degree of carbonation, can also be influenced by adjusting the differential pressure between the liquid flow and the injected gas and / or the properties of the continuous mixer, in particular by varying the gap width in a continuous mixer with a nozzle chamber described below (e.g., according to the teaching of WO 2004 / 024 306 A1). This is particularly advantageous compared to the carbonators known from the prior art, in which a variation in the degree of carbonation is achieved by simply adding non-carbonated water to the carbonated water in a variable mixing ratio.This is usually achieved through the use of a control system with solenoid valves, which, depending on the carbonation level setting, allow different amounts of still water to flow from a parallel line to the carbonated water into the outlet. This is preferably done using a control system with a timer. The cycle rate determines the carbonation level in the beverage. Carbonators of this type therefore require a high level of technical complexity, which is associated with high maintenance costs. The complex construction and the required maintenance inevitably result in cost disadvantages. On the other hand, there are hygienic disadvantages, as there is a risk that the pipe network for non-carbonated water (still water) is exposed to a high risk of contamination via the tap.The carbonator according to the present invention, however, does not have such an additional supply line for still water, thus fundamentally avoiding the disadvantage of increased technical complexity. Furthermore, virtually all of the water remaining in the lines of the carbonator according to the invention when not in use is carbonated and thus has a significantly reduced tendency to germ formation.

[0029] In combination with a variable flow rate regulator, which can also be manufactured using plastic injection molding technology, continuously adjustable carbonation results can be achieved at minimal production costs. Finally, the differential pressure valve optionally arranged in the inlet of the continuous mixer, i.e. the gas pressure regulator for regulating the gas pressure as a function of the liquid pressure, can also be manufactured using plastic injection molding technology, which leads to a further reduction in production costs. Finally, it should be noted that because the pressures that occur when carrying out the method according to the invention, e.g. in a device according to the invention, are not too high, even the liquid or gas-carrying lines can be made entirely or partially of plastic, in particular can be manufactured using plastic injection molding technology.

[0030] If as many of the aforementioned components as possible—differential pressure valve, flow mixer, (fixed or variable) flow regulator (downstream of the flow mixer), (fixed or variable) flow restrictor (upstream of the flow mixer), liquid or gas-carrying lines, and connectors—are made of plastic, this allows for a very high level of integration of several components into a single component, while also minimizing connection problems at the connection points between individual components and lines. An example of this would be the integration of a differential pressure valve, flow restrictor, and flow mixer into a single component, or alternatively, a flow mixer and flow regulator or variable throttle, particularly including the necessary connecting lines.

[0031] Furthermore, it is also possible to design the flow mixer and the flow rate regulator or throttle as fixed—i.e., non-adjustable—parts, and to configure the differential pressure regulator as a variable one. In this configuration, a user can adjust the degree of carbonation by varying the flow restrictor located upstream of the flow mixer in the gas stream and / or the differential pressure between the liquid and the incoming gas.

[0032] Particular advantages of the method and device according to the invention arise when the pressure difference between the fed-in gas and the liquid is set to approximately zero. In this way, the formation of gas bubbles in the lines / components downstream of the continuous mixer can be reliably prevented, thereby ensuring a very homogeneous dispensing pattern. This is possible, for example, with the continuous mixer with a fixed nozzle chamber and annular gap described in the following exemplary embodiment. Furthermore, operation with an essentially negligible differential pressure is possible with a continuous mixer according to WO 2005 / 105 279 A1, the teaching of which, like the teaching of WO 2004 / 024 306 A1, is fully incorporated into the teaching of this application by this reference. It should be noted, however, that operation of the device and implementation of the method are also possible with a pressure difference other than zero.

[0033] Depending on the continuous mixer used, the gas pressure can generally be either above or below the liquid pressure. In particular, the use of a continuous mixer according to the teaching of WO 2004 / 024306 A1 allows the setting of a gas pressure that is also below the liquid pressure. In this case, particularly efficient gas enrichment with minimal bubble formation can be achieved.

[0034] A device according to the invention is particularly suitable for carbonating drinking water. In this case, the connection for the liquid flow is usually connected to a drinking water pipe or to a storage tank and a downstream booster pump. The connection for the gas is connected to a carbon dioxide cylinder via the differential pressure regulator, and the tap connection is connected to a tap valve via the flow rate regulator.

[0035] The process according to the invention for enriching a liquid stream with a gas is based on the following process steps: a) the liquid stream is passed through a continuous mixer, b) the gas is fed into this continuous mixer so that it mixes with the liquid stream, whereby a setpoint for the pressure difference between the liquid stream and the fed gas is specified.

[0036] The invention is essentially based on limiting the flow rate of the gas fed into the continuous mixer, for example, by means of a flow restrictor. Suitable devices for carrying out the process are given above by way of example.

[0037] Particularly high interference immunity, particularly under changing operating conditions, can be achieved by keeping the pressure difference between the liquid flow and the injected gas constant in a suitable manner. Details of this have already been discussed in connection with preferred embodiments of the device according to the invention; reference is made to these. In particular, a differential pressure regulator can be used to keep the pressure difference constant. In this case, it has been proven that the setpoint of the pressure difference can be adjusted particularly easily if an adjustable differential pressure regulator is used that is suitably adjusted.

[0038] Alternatively, an adjustable flow restrictor, e.g. an adjustable throttle or an adjustable orifice, can be used to adjust the setpoint of the pressure difference, which is set appropriately.

[0039] Depending on the device used to carry out the process, the process according to the invention allows for a sensitive adjustment of the degree of enrichment of the liquid stream. This can be influenced, in particular—provided the appropriate technical equipment is available—by performing the following process steps: a) Setting the setpoint for the pressure difference between the liquid flow and the injected gas, b) Adjusting the nominal diameter of the flow restrictor, c) Introducing the liquid stream to be enriched into a tubular continuous mixer with a nozzle head having a nozzle ring gap with variable gap width, and adjusting the gap width of the nozzle ring gap.

[0040] Below, several exemplary embodiments of devices according to the invention are described with reference to the figures. These exemplary embodiments are to be understood as examples, meaning that the invention is not limited to these specific embodiments. In particular, features or groups of features of the exemplary embodiments can also be combined—to the extent technically possible—with the above-described embodiments of the invention. Short description of the characters Fig. 1 shows a simplified circuit diagram of an example of a device for enriching a liquid stream with a gas. Fig. 2 shows a simplified circuit diagram of an embodiment of a device according to the invention for enriching a liquid stream with a gas Fig. 3 shows a simplified circuit diagram of an example of a device for enriching a liquid stream with a gas.

[0041] The Fig. 1 and Fig. 3 examples shown do not fall within the scope of protection.

[0042] The Fig. The device 10 shown in Figure 1 was developed specifically for the continuous carbonation of drinking water at the end user or in restaurants. It comprises a water-side connection 12, a gas-side connection 14, and a tap connection 16. The water-side connection 12 is connected to a drinking water line 18 via a drinking water filter 120, a backflow preventer 140, and a shut-off valve 160. The gas-side connection 14 is connected to a carbon dioxide container 22 via a shut-off valve 20, wherein reference numeral 24 denotes a gas-side safety valve. The tap connection 16 is equipped with a tap 26.

[0043] The actual carbonation, i.e. enrichment of the drinking water with carbon dioxide, preferably takes place in a tubular continuous mixer 28 with a nozzle head 30, a mixing chamber 32 and a settling chamber 34. The nozzle head 30 is advantageously designed as described in WO 2004 / 024 306 A1. It accordingly comprises a nozzle ring gap 36, which is connected to the water-side connection 12 via a water supply line 38, and a gas injection nozzle 40, which is arranged in a central core 41 and is connected to the gas-side connection 14 via a gas supply line 42. The width of the nozzle ring gap 36 can be advantageously adjusted; in the mixing chamber 32, the centrally injected gas mixes extremely efficiently with the surrounding water flow to form a water-gas mixture. This mixture then advantageously flows via micro sieves 44 into the settling chamber 34.The microsieves 44 ensure more homogeneous bubble formation in the liquid stream. The mesh size of the microsieves 44 can also be used to control the size of the gas bubbles in the water stream.

[0044] In contrast to the design of the continuous mixer described in WO 2004 / 024306, the design described in Fig. The design of the continuous mixer 20 shown in Figure 1 does not have a pressure stabilizer at the outlet of the settling chamber 34. Instead, the gas-water mixture flows directly into a tapping line 48 via an outlet opening 46 of the settling chamber 34.

[0045] An adjustable pressure control valve 50 and a backflow preventer 52 are arranged in the gas supply line 42. The adjustable pressure control valve 50 regulates the pressure difference between the gas in the gas supply line 42 and the water in the water supply line 38 to an adjustable, constant setpoint, which can in particular be zero. The setpoint essentially determines the achieved degree of carbonation. During operation of the pressure control valve 50, an actuator 54 (piston or diaphragm) of the pressure control valve 50 is subjected to the water pressure in the water supply line 38 and the gas pressure in the gas supply line 42. If the difference between the gas and water pressures exceeds a predetermined setpoint, the gas flow in the gas supply line 42 is throttled via a gas valve 56 connected to the actuator 54. If the difference between the gas and water pressures falls below the predetermined setpoint, the gas valve 56 is opened again accordingly.A constant setpoint for the pressure difference can be specified, for example, via a spring 58. By selecting the preload of the spring 58, the specified setpoint for the pressure difference can be adjusted. Depending on the arrangement of the spring 58, the gas pressure can be higher or lower than the water pressure. In principle, however, it is also possible to dispense with the spring entirely, since springs often exhibit considerable variation due to manufacturing processes, can fatigue or break prematurely, and can result in hygiene disadvantages.

[0046] A special case here is a pressure regulator with a pressure control piston that has a transmission ratio of 1:1 and no spring means to specify a pressure difference. Such a pressure regulator then ensures that the gas pressure in the gas supply line 42 is approximately equal to the water pressure in the water supply line 38. It also offers hygienic advantages over pressure regulators that use spring means, since in these cases the spring means frequently comes into contact with liquid and can thus be a source of germ formation.

[0047] If, with this special pressure regulator, it is desired to set a (dynamic) water pressure in the flow mixer 28 that is lower than the gas pressure in the flow mixer 28, the width of the nozzle ring gap 36 can be reduced, for example, or an (adjustable) throttle valve (not shown) can be installed in the water supply line 38 between the pressure regulator 50 and the flow mixer 28.

[0048] In the example according to Fig. 1, however, the water pressure in the flow-through mixer should be higher than the gas pressure in the flow-through mixer, as can be advantageous, for example, with a Venturi mixer. Here, a non-adjustable throttle 62, adapted to the typical operating conditions, is inserted as a flow limiter in the gas line 42 between the pressure regulator 50 and the flow-through mixer 28. In the example shown, this throttle 62 is integrated into the housing of the pressure control valve 50. In principle, the flow limiter, i.e. here the throttle 62, can also be designed as a separate component. An example of another suitable flow limiter is a fixed orifice plate.

[0049] Reference numeral 52 indicates a backflow preventer, which ensures that no water enters the gas supply line 42 if, for example, the gas pressure in the gas supply line 42 falls below the water pressure in the flow mixer 28. This is the case, for example, if the gas container is largely empty. Of course, the puncture of the backflow preventer 52 can also be integrated into the pressure control valve 50. The latter also applies to the safety function of the safety valve 24 described above.

[0050] In the tap line 48, downstream of the flow mixer 28, a simple flow rate regulator 60 is arranged, which keeps the flow rate of the drinking water stream in the tap line constant largely independent of pressure fluctuations, e.g. in the fresh water supply.

[0051] By combining a constant pressure difference between the gas in the gas supply line 42 and the water at the water supply line 38 by regulating the gas feed pressure, on the one hand, with a limiting of the gas flow rate in the gas supply line 42 by means of a flow restrictor 62, on the other hand, a very uniform and stable, fixed carbonation can be achieved. Even with strong pressure fluctuations in the drinking water line, especially during short dispensing cycles, carbonation always functions optimally without any readjustment.

[0052] A further (optional) improvement of the dispensing pattern is achieved by the simple flow rate regulator 60 arranged in the dispensing line 48. If the flow rate regulator 60 is also adjustable, the user can also select the degree of carbonation by adjusting it. Amazingly, it was also found that even with very simple flow rate regulators, such as those used as standard inserts in sanitary fittings under the name "water saver", surprisingly good results can be achieved. The results achieved were even better than with complex water-side pressure controls, which have previously been used to try to regulate a constant water pressure and / or gas pressure in the flow mixer. Such simple flow rate regulators are based, for example, onThe functional principle is that an O-ring is arranged in a through-channel around a central control body with longitudinal grooves in such a way that it is deformed by the pressure difference between the water inlet and outlet sides and pressed into the longitudinal grooves of the control body. As the flow pressure increases (i.e., increasing flow rate or volume), the O-ring reduces the free flow cross-section of the longitudinal grooves in the central control body. As the flow pressure decreases (i.e., decreasing flow rate or volume), the O-ring returns to its original shape, whereby the free flow cross-section of the longitudinal grooves increases again. Such "water-saving inserts" are not only extremely cost-effective, but have also been tried and tested as standard inserts in sanitary fittings. Furthermore, these inserts can be easily installed in the tap line 48 or the tap valve 26. Adjustable flow rate regulators are also available.In the latter case, the central control body with the longitudinal grooves is conical and adjustable relative to the O-ring.

[0053] It is also possible to use a non-adjustable pressure regulator 50, ie a pressure regulator 50 with a fixed pressure difference setpoint, as shown in Fig. 2. The reference numerals not explicitly described here in Fig. 2 correspond to the identical reference numerals in Fig. 1. In this exemplary embodiment, an adjustable throttle 64 is inserted as an (adjustable) flow limiter in the gas line 42 between the control valve 50 and the continuous mixer 28. Depending on the design of the pressure regulator 50, the differential pressure between gas and the liquid to be enriched can be positive, negative, or zero. Here, for example, a constant, fixed preload can be generated by means of a spring element in the pressure regulator 50. Due to the adjustable throttle 64, the gas pressure will generally be lower than the liquid pressure. This is not absolutely necessary, however; depending on the application and the continuous mixer used, it can also be equal to or higher than the liquid pressure. The degree of carbonation can basically be adjusted here by adjusting the adjustable throttle 64, the flow rate regulator 60, and the gap width of the nozzle ring gap 36. These influencing variables can be adjusted individually or jointly if necessary.can also be adjusted jointly.

[0054] With the continuous mixers according to Fig. 1 and Fig. 2. In extensive tests, exceptionally good carbonation results were achieved with the combined differential pressure / gas flow rate control. However, it can be assumed that with other continuous mixers, such as venturi mixers or continuous mixers with sieve inserts, a significant improvement can be achieved by combining a constant pressure difference between the gas in the gas supply line 42 and the water in the water supply line 38 by regulating the gas feed pressure on the one hand with a constant gas flow rate in the gas feed line 38 by means of a flow limiter on the other hand. 16 of the carbonation result can be achieved. The degree of carbonation (the carbonation output) is adjusted in an extremely simple, reliable, and stable manner by the pressure difference between the gas and the water in the flow mixer 28 and by the gas flow rate specified by the flow limiter. Furthermore, this embodiment also offers the possibility of influencing the carbonation via an adjustable flow limiter 60 in the dispensing line 48.

[0055] Fig. Finally, Figure 3 shows an example of a device that has a simplified structure and can be used in particular when the operating conditions are essentially constant. The reference numerals not explicitly described here correspond to the identical reference numerals in Fig.1. The control valve 50 is replaced by two adjustable valves 66, 68, which individually, i.e. independently, control the gas feed pressure into the gas feed line 38 and the liquid pressure in the liquid feed line 42. By appropriately adjusting the valves 66 and 68, it is possible to specify a fixed differential pressure between the gas and the liquid to be enriched, which can be considered essentially constant due to the only slightly changing operating conditions. The device for adjusting the differential pressure between the gas and the supplied liquid flow is therefore implemented here by the two valves 66, 68.

Claims

[1] Device for enriching a liquid stream with a gas, comprising: a) a continuous mixer (28) with a connection for the liquid stream (12), a connection for the gas (14) and a discharge connection for the enriched liquid stream (16), and b) a device for adjusting the differential pressure between the gas and the supplied liquid stream, characterized by c) a flow limiter arranged between the device for adjusting the differential pressure and the continuous mixer (28) for the gas flow supplied to the continuous mixer (28), wherein the flow limiter is adjustable, wherein the device for adjusting the differential pressure between the gas and the liquid flow is designed as a differential pressure regulator (50) which regulates the feed pressure of the gas in such a way that the pressure difference between the supplied liquid flow and the fed-in gas is largely constant. [2] Device according to claim 1, characterized by that the flow restrictor has an inner diameter of maximum 2.0 mm. [3] Device according to claim 1, characterized by that the flow restrictor has an internal diameter of at least 0.2 mm. [4] Device according to claim 1, characterized by that the flow limiter is designed as a throttle (52) or as an orifice. [5] Device according to claim 1, characterized by that the differential pressure regulator (50) is adjustable. [6] Device according to one of claims 1 to 5, wherein the continuous mixer (28) comprises a nozzle head (30) and a mixing chamber (32) adjoining thereto, and the nozzle head (30) has a nozzle ring gap (36) and a gas injection nozzle (40) arranged centrally to the nozzle ring gap (36), wherein the connection for the liquid flow (12) is connected to the nozzle ring gap (36) and the connection for the gas (14) is connected to the gas injection nozzle (40). [7] Device according to claim 6, wherein the width of the nozzle ring gap (36) is adjustable. [8] Device according to one of claims 1 to 7, wherein a) the connection for the liquid flow (12) is connected to a drinking water pipe (18) and the connection for the gas (14) is connected to a carbon dioxide bottle (22), and b) the dispensing connection (16) is connected to a dispensing valve (26). [9] A process for enriching a liquid stream with a gas, wherein a) the liquid stream is passed through a continuous mixer (28) b) the gas is fed into this continuous mixer (28) so that it mixes with the liquid stream; and c) whereby a setpoint value for the pressure difference between the liquid flow and the injected gas is set, characterized by , that d) the flow rate of the gas fed into the continuous mixer (28) is limited by means of an adjustable flow limiter, wherein the pressure difference between the liquid flow and the fed-in gas is kept constant and a differential pressure regulator is used to keep the pressure difference constant. [10] Method according to claim 9, characterized by that the differential pressure controller is adjusted to set the setpoint of the pressure difference. [11] Method according to claim 9, characterized by that the flow limiter is adjusted to set the setpoint of the pressure difference. [12] Process for the variable enrichment of a liquid with a gas, characterized by the process steps according to claim 9, wherein the degree of enrichment is adjusted by one or more of the following process steps: a) Setting the setpoint for the pressure difference between the liquid flow and the injected gas, b) Adjusting the nominal diameter of the flow restrictor, c) introducing the liquid stream to be enriched into a tubular continuous mixer (28) with a nozzle head (30) having a nozzle ring gap (36) with a variable gap width, and adjusting the gap width of the nozzle ring gap (36). [13] Method according to one of claims 9 to 12, characterized by that the feed pressure of the gas is less than or equal to the pressure of the supplied liquid stream, preferably less than the pressure of the supplied liquid stream.

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