53,492 ~038345 This invention relates to a process and apparatus for preparing and dispensing carbonated liquids by mixing a given quantity of cooled carbon dioxide-containing water and a pre-determined quantity of a fluid flavouring substance such as syrup or concentrate.
Drinking liquid containing flavouring or aroma sub-stances are to a large extent factory-produced and packed in containers such as cans and bottles, and transported in large bundles to the place of distribution or sale. This is costly in terms of packing material, storage and transportation space, and moreover the final user has to carry large quantities of water home with the drinksO There is also the attendant problem of eliminating or returning and re-processing empty containers.
Automatic dispensing machines are known which dispense drinks packed in containers on inserting a coin or pressing a button. The volumetric capacity of such automatic machines is limited, and the problem remains of disposing the empty con-tainers.
It is also known to keep lemonade or other drinking liquid in large storage tanks under corresponding cooling in automatic drink machines, and to dispense individual predeter-mined quantities from these tanks into drinking cups placed in readiness on inserting a coin, by means of pumps or gas pressure.
For hygienic reasons such equipment must be cleaned before refilling, and the liquid must be prevented from decaying by corresponding cooling systems and/or chemical additives.
Similar problems also exist in automatically operating dispensing devices in which carbonated water and a fluid flavouring substance such as syrup or concentrate, are held separated in tanks in the automatic machine and on inserting a coin or the like, respective individual portions are fed simultaneously to a drinking cup, possibly by way of a mixing zone. A difficulty of these dispensing devices is that uniform quality of the dispensed drink cannot be always guaranteed, and as the flavouring substances are intended for immediate use, hygiene requirements cannot always be guaranteed, so that pre-serving agents must be added. As such preserving agents aregenerally carriers of flavour, the taste of the finished drink is thereby considerably influenced. Such automatically operat-ing dispensing devices have therefore had only a limited success in practice.
Such known automatic drink machines or automatically operating dispensing machines comprise relatively heavy, voluminous equipment of high costly technical content. For household needs, such equipment is unsuitable.
The object of the present invention is to provide a process of the initially described type which may be installed economically in bars, factories, administrative buildings and particularly in private households, and which provides drinks of particularly high and uniform ~uality satisfying all hygienic requirements and offering a relatively large choice of drinks of different tastes in a small space.
~ his object is attained in accordance with the inven-tion, in that -the predetermined quantity of the cooled carbon dioxide-containing water is allowed to flow in the form of a weak stream under the normal pressure of the surrounding atmos-phere through a mixing zone to a dispensing point, and the pre-determined quantity of syrup or concentrate is fed under its own static pressure into the water stream in the mixing zone, and the mixing of the two components and dispensing of the finished drink under the static pressure of the mixed liquid are so conducted that a ready-to-drink, cold, C02-containing drink is prepared and dispensed whereby all stages are pressure-less.
Alternatively, but preferably, the invention provides for the predetermined quantity of flavouring substance to be fed at a temperature appreciably above a predetermined tempera-ture of preferably 5C into the C02-containing water stream which is cooled to appreciably below the predetermined tempera-ture, a part of the carbon dioxide being liberated in a sudden burst simultaneously with the addition of the flavouring substance and the two components becoming mixed and homogenised with the aid of the liberated gas~
The flavouring substance may be added in the form of a lemonade syrup of fruit juice concentrate. In this case the flavouring substance is desirably held in store with a sugar content sufficiently high for its self-preservation at ambient temperature, and the predetermined quantity is fed into the water stream in the region of the mixing zone at ambient temperature.
The predetermined quantity of cooled carbon dioxide-containing water is taken from a water main in the normal manner. The water is then finely impregnated in the preparation zone at a temperature near its freezing point with carbon dioxide to approximately maximum solubility, and the predeter-mined quantity is conveyed from the preparation zone to the mixing zone after reducing the pressure to ambient pressure.
In the previous automatic preparation of carbon dioxide-containing drinks, such as drinks of the cola type, orange drinks, and lemonade drinks, the aromatic flavouring substance in fluid form, e.g. as a syrup or concentrate, was fed into the carbon-dioxide-containing water under a determined pressure through a delivery metering valve in an attempt to generate a homogeneous mixing effect with the li~ewise pressur-ised carbon dioxide-containing water by the pressure of the two components. The present invention however takes a different path.
In known cases the carbon dioxide-containing water is led through pressure lines into the mixing head, where the water is mixed with the given quantity of pressurised flavouring sub-stance to form the finished drink, which is then delivered from the mixing head into a drinking cup. In this case the syrup or concentrate has a relatively high water content. This water content leads to considerable dilution of the carbonated water so that the carbon dioxide content of the finished drink is limited.
Furthermore, in mixing the two portions by way of pressurised feeding, a larger proportion of the carbon dioxide escapes unused because of enforced turbulence, i.e. it is no longer contained in the finished drink.
io~8345 Furthermore, in known processes and equipment, difficulties arise because externally determined intensive mixing takes place due to the specific construction of the mixing zone. The resultant high turbulence favours the escape of unusable carbon dioxideO Because of the high water content of the syrup or concentrate, in order to attain a desired relatively low temperature of the finished drink the concen-trate or syrup must to a large extent be cooled, if the drink temperature is not to be too high after mixing. In order to obtain good mutual mixing of the flavouring substance and eater in the mixing zone by means of the enforced mixing, the flavour-ing substance has until now been sufficiently fluid, and for this reason the water content of the flavouring substances has been relatively high.
In contrast, the presently disclosed process is based on the concept of feeding the flavouring substances at the highest possible concentration, iOe. with the smallest possible water content, into a substantially calm flowing stream of cooled carbonated water and into a zone which is in contact with the surrounding atmosphere, i.e. which is under atmospheric pressure. The new process expressly avoids the enforced mixing of the flavouring substances and water. Instead of this, the water is impregnated previously with carbon dioxide to the maximum possible primary degree of carbon dioxide saturation as determined by the water temperature, and is brought together with the flavouring substance which has a higher temperature than the water. Hence when the fed quantity of flavouring substance enters a bounded region at the flavouring substance feed point, an explosiVe liberation of part of the carbon dioxide contained in the water occurs because of the sudden rise in temperature in this region. This produces such a turbulence in this locally bounded region that, as determined in practice, a very intensive mixing of the flavouring sub-stances and water occurs. As also shown in practice, the liberation of carbon dioxide is thereby limited to an extent determined by the rise in water temperature to the mix tempera-ture after mixing. The finished drink is therefore under the present process, impregnated with carbon dioxide to the degree of saturation determined by the mix temperature of the drink.
It can therefore be shown in practice that in spite of the use of carbon dioxide for mixing the flavouring substances and water, the carbon dioxide content of the finished drink delivered into a drinking cup is in practically all cases higher than the corresponding drink previously mixed in bulk and drawn off under the pressure in the storage tank. The fine impregnation of the water with carbon dioxide according to the disclosed process gives the advantage that the carbon dioxide remains in the finished drink contained in the drinking cup longer on standing than is usual with comparative drinks. In spite of the use of flavouring substances of higher concentra-tion than in the normal system, i.e. with a smaller water content and lower fluidity, the new process leads to complete homogenization of the components by the time of their delivery into the drinking cup. The lower water content of the flavour-ing substances also leads to an increase in the ratio of car-bonated water to flavouring substance in the finished drink.
Hence even if the flavouring substances are fed into the carbonated water at ambient temperature, the temperature of the finished drink is lower than in the case of other auto-matic drink machines, in which the components are mixed during delivery.
The smaller water content of the flavouring sub-stances makes it practically possible to use a syrup with a sugar content sufficiently high to guarantee self-preservation.
whereas in known automatic drink machines a syrup generally with a maximum sugar content of up to 54%, i.e. approximately 54 Brix, may be used, in the new process a self-preserving syrup with a Brix value of substantially more than 60, and indeed up to Brix values of over 71, may be used. The self-preservation of the syrup makes the addition of preservation agents, the cooling of the syrup supply or frequent cleaning of the equipment unnecessary. As the carbon dioxide-containing water in the process according to the invention satisfies all hygienic requirements, only the mixing zone exposed to atmos-pheric pressure need be cleaned. Thus both the component cost and maintenance cost of the equipment is considerably reduced.
The process may thus be effected in a much cheaper manner from the equipment point of view.
The carbonated water is fed to the mixing zone at a temperature preferably between approximately 0 and 2C. In relation to the correspondingly considerably smaller quantity of higher temperature flavouring substance, a drink temperature, i.e. a mix temperature, is attained of about 5C.
As enforced mixing may be dispensed with, it is also 1~38345 possible to purge the mixing zone with pure carbon dioxide-containing water before and after adding t~e flavouring sub-stance when producing a drink portion, so that no flavouring substance residues can build up in the mixing zone. Any such residues have such a high sugar content that they in any case do not cause hygienic difficulties.
The preparation of the water for its portion-wise delivery is a further important factor of the new process.
According to the new process, a water supply in a preparation zone is surrounded by an evaporation surface cooled to a temperature of less than 0C, and a weak convective stream is compulsorily maintained in the water supply along this surface.
The carbon dioxide gas is fed under pressure through a finely porous surface into the convective stream under the fresh water which is sprayed on to the top surface of the water supplyO In this manner cooling of the water to a temperature between 0C
and 2C is guaranteed. The occasional make-up fresh water requirements are covered by feeding the fresh water in the form of a fine cloud or spray into the headspace above the water supply, so that the water addition in no way produces turbulence or disturbance in the water supply.
The pressurised feed of carbon dioxide gas is done in a manner which guarantees very fine impregnation of the water supply up to its maximum degree of saturation as determined by the temperature. This is done by feeding the gas in very fine bubbles which are taken up by the weak and practically laminar stream in the water supply and are distributed in the water supply so quickly and uniformly that no larger bubbles can form, and which would lead to carbon dioxide loss. The weal convec-tive stream also ensures completely uniform cooling of the water to the required lower temperature.
The operation is thereby carried out with very low water temperature and simultaneous impregnation in such a manner that the water is impregnated to the high saturation level corresponding to the very low water temperature. The delivery of the metered quantity of water consequently takes place from the water supply which is always in practice fully homogeneous both with regard to carbon dioxide content and temperature.
The relatively low water temperature is obtained in the new process in such a manner that with the aid of the con-vective stream only a very thin layer of ice is allowed to form on the side of the cold surface facing the convective stream, so that direct heat transfer from the water to the cooling surface occurs without being hindered by the heat-resistant ice layer. However the new process can also be operated using an ice layer as a cold store.
This is attained by a correspondingly guided convec-tive stream and a corresponding arrangement of the cooling surface in the water store. According to the new process, the convective stream may be guided along the cooling surface in the water store in such a manner that only a very small thickness of ice layer forms on that side of the cooling surface facing the stream, and does not hinder the heat trans-fer, while in that part of the water store on the other side of the cooling surface, any current is hindered or so reduced that relative to the flowing part of the water store an ice layer can build up behind the cooling surface of sufficient thickness to serve as a cold reservoir.
The larger bubbles of carbon dioxide which to a limited extent form in the carbonating device are added to the delivered water quantity from the store in the region of the mixing zone, and assure better mixing of the water with the flavouring substances.
In carrying out the new process, there is provided a drink preparation and delivery apparatus with devices for the metered dispensing of flavouring substances in the form of syrup or concentrate and of cooled carbon dioxide-containing water, and a device for mixing water and flavoring substances and at least one dispensing point for the finished mixed drink.
Accordlng to a further characteristic of the inven-tion, in this apparatus the mixing device comprises a flow channel slightly inclined to the horizontal between the dis-pensing device for the water and the dispensing point for the drink, this channel being under atmospheric pressure, and the dispensing device for flavouring substances being so associated with the flow channel that the metered quantity of flavouring substances flows directly into the water stream in the flow channelO
Preferably a device for very finely impregnating the water with carbon dioxide to the maximum saturation degree determined by the temperature of the cooled water is connected in series with the water dispensing device, while a storage device which holds the flavouring substance at a temperature 1~8345 .
above the temperature of the cooled water, preferably at ambient temperature, is associated with the dispensing device for the flavouring substance.
The apparatus may be easily constructed to associate one or more storage and metering devices for various flavour-ing substances with the flow channel for the carbonated water, so that with the same apparatus by simply operating a selection device, drinks of the most varied flavour, including pure cold flavourless carbonated water, can be dispensed. The apparatus can be produced at such low constructional cost and with such low space requirements that the apparatus is installable not only in bars, factories or public buildings, but also in private households, to dispense drinks cheaper than previously possible.
All transportation problems with the exception of the transpor-tation of carbon dioxide cylinders or storage containers for the flavouring substances are eliminated. Equally, a household is liberated therewith from all previous problems connected with the transportation containers, such as bottles. The appara-tus operates hygienically, absolutely trouble-free and requires only small maintenanceO The energy requirement is no more than with a normal household refrigerator.
The invention will now be described by way of examples with reference to the drawings in which:
Figure 1 is a side view of a drink dispensing appara-tus;
Figure 2 is a vertical section through a carbonating device of traditional construction;
Figure 3 shows a carbonating device according to the invention;
Figure 4 shows a storage and metering device of traditional construction for fluid flavouring substances;
Figure 5 shows a storage and metering device for flavouring substances according to the invention;
Figure 6 i5 a drink mixing head of traditional type depicting the dispensing of a drink;
Figure 7 shows the mixing zone of the drink dispens-ing apparatus, at the beginning of the dispensing operation;
Figures 8 and 9 are views similar to Figure 7 of the mixing zone during and immediately at the end of a dispensing operation;
Figure 10 is a vertical section through a preferred embodiment of a processing device for the carbonated water be.fore start-up; and Figure 11 is a view similar to Figure 10 of the processing device during normal operationO
The apparatus shown in Figure l provides drinks of different tastes as desired.
The apparatus comprises, in a housing A, a bank of storage containers lO_ to lOd for different flavouring sub-stances, the flavouring substances being in the form of a syrup of high concentration, iOe. they have a value appreciably above 60 srix.
In Figure 1 the storage containers lOa to lOd are closed containers, a metering device 13 being connected to each lower end thereof for delivering a predetermined quantity of syrup from the syrup store 9. The liquid level in the storage container lOa is indicated by 14, and the head room above the liquid level by 15.
The necessary air for delivery is fed through a tube 11 to a point well below the liquid level 14 and just above the delivery device 13. Further details are described in connection with Figure 5.
In the housing A there is also a preparation device for the carbon dioxide-containing water. The preparation device comprises a pressure-tight tank 26 in which a store of cooled water 27 is contained. The fresh water is fed by way of a control valve 30 through a spray device 31 and the carbon dioxide gas is fed by way of a control valve 28 through a distribution head 290 while the carbonated prepared water is removed from the store through a line 32 and through a control valve 33 and pressure balancing device 34 to a mixing zone. The preparation device will be described in more detail in connection with Figure 3 and Figures 10 and llo The water under pressure in the store 27 leaves the device 34; suffering pressure drop, and flows into a flow channel in the form of an open trough 38. This trough 38 is open to show that the flow channel is connected to atmosphere to allow pressure equalisation. In practice the flow channel or trough 38 is hygienically isolated from the atmosphere.
The trough floor is slightly inclined to the hori-zontal, towards a drink dispensing point 40. The device 34 and dispensing point 40 are at opposite ends of the trough, so that the carbon dioxide-containing cooled water flows in a weak current over the total length of the trough.
Figure 1 shows that the metered quantity of flavour-ing substance flows directly into the water stream flowing in ~138345 the trough 38 irrespective of the choice of flavouring sub-stance. The dispensing point 40 has a relatively large outlet cross-section so that the finished drink can enter a cup disposed under the dispensing position with relatively low flow velocity and turbulence.
Figure 2 shows a carbonating apparatus of traditional type. The apparatus comprises a pressure-tight tank 16 in which a water store 17 is contained under the formation of a headspace 16a. Carbon dioxide gas from a corresponding pressurised source is fed through the line 18 and control valve 19 and through the pipe 20 extending into the tank 16 and nozzle 21 into the water store in the form of bubblesO The fresh water reaches the water store from a pressurised water source through the control valve 23 and an outlet nozzle 22 in the tank, as shown in Figure 2.
The water store is mixed with the carbon dioxide bubbles and fresh water by turbulence which is generated both by the in-flowing water and by the rising gas bubbles. Metered quantities of carbonated water are removed from the store through the pressure line 25 and control valve 24, and fed to a mixing head.
The fresh water arrives cooled in the tank 16. It is evident that the carbon dioxide enters the water store in relatively large bubbles, the bubbles being able to combine during their upward movement because of the turbulence. The carbon dioxide gas which remains in the water store is present in relatively coarse bubblesO As the in-flowing fresh water has to contribute substantially to the mixing operation, it flows with relatively high velocity into the water store and aids turbulence, which for its part aids the formation of larger carbon dioxide bubbles ~ 03834s ~
and a maximum impregnation is not attained because of the relatively high water temperatures. The metered water quanti-ties removed through the pressure line 22 have therefore only a relatively low degree of carbon dioxide saturation.
In the preparation device shown in Figure 3, a pressure tank 26 with a water store 27 and headspace 26a are likewise provided. The cooled fresh water is fed under pressure through the valve 30 to a spray head 31 and enters the head-space 26 as a fine water mist or spray, which deposits on the upper surface of the water store 27 slowly and without produc-ing turbulence.
The carbon dioxide is fed under pressure through the control valve 28 to a porous body 29, which allows the gas to emerge only in very fine bubbles, which have only a small buoyancy and therefore a correspondingLy larger residence time in the water store 27, than the correspondingly larger bubbles in the known device. The very fine bubbles can therefore dis-perse substantially more easily and completely over the total cross-section of the water store 27 immediately at the level of the porous body 29, so that the total water store 27 is impregnated with the carbon dioxide gas substantially more uniformly and quickly. The bubbles have only a small tendency to combine, as they are dispersed constantly and smoothly in the water store and are therefore exposed to no noticeable turbulence.
If it is assumed that in both the compared devices of Figures 2 and 3 the water store is at the same temperature after cooling, then with the device as shown in Figure 3 the water store 27 is impregnated with carbon dioxide gas to a substan-tially higher degree of saturation. The impregnated water removed through the line 32 under pressure has also a con-siderably higher carbon dioxide content than in the known case.
In the illustrated example of each case, the gauge pressure in the headspace of the tank is about 6 bars. While in the known case the withdrawn water quantitv flows under pres~ure to the mixing head through the pressure reducing cone, in the device according to this embodiment of the invention the withdrawn water reaches a pressure reducing device 34 by way of a control valve 33 and is then exposed exclusively to atmospheric pressure for its further transportation.
Figures 4 and 5 show storage and metering devices of known type and according to an embodiment of t~e invention respectively, for a flavouring substance of syrup type.
In the traditional device as shown in Figure 4, a store 1 of syrup is present in a storage container 2, the upper surface of the syrup being indicated by 8. The headspace 7 is connected through a pressure line 3 and pressure valve 4 to a pressurised carbon dioxide source. The increased pressure in the headspace serves for the withdrawal of determined quantities of syrup through the rising pipe 6 and metering valve 5. It is evident that in this known device the syrup must possess a relatively high fluidity and therefore a relatively high water content. In practice a syrup is used with a concentration of up to a maximum of 54 degrees Brix. This means that the syrup must be made to last by additional means, by cooling or preser~
vation agents. In addition streaks and incrustations build up on the inner surfaces of the tank, and make it necessary to properly clean the tank 2 before re-filling for hygienic reasons.
In contrast, the storage device shown in Figure 5 comprises a storage container 10 which is closed and has its withdrawal opening disposed at the bottom. In this case the metering valve 13 is connected directly to the delivery opening of the container. The metering valve comprises a movable valve body 13 which can be lifted from the indicated closed position by an electromagnet 13a into an open position.
The syrup is withdrawn from the store 9 by gravity. The head-space 15 of the container 10 is in direct connection neither with the atmosphere nor with a pressurised gas source. When a predetermined quantity of syrup is withdrawn from the storage container a relative lowering of pressure occurs in the head-space. In order to equalise the pressure on withdrawal, a vent point 12 is provided in the container, its boundary sur-face between the syrup and air lying at a considerable distance under the level 14 in the store 9 and only a small distance from the delivery opening of the container. In the illustrated example the boundary surface 12 is in the form of the lower end of a vent pipe 11 leading upwards through the container and container cover to the surrounding atmosphere. The syrup ~uantity under the boundary surface 12 is therefore under a low static pressure. when syrup is withdrawn, air in the form of small bubbles can rise from the boundary surface 12 through the syrup store 9 and into the headspace 15. Evidently the vent pipe may also be connected to the lower part of the con-tainer 1~. what is important is that an underpressure is present throughout the closed headspace 15 which does not allow the store 9 to come into contact with the air. On the way through the syrup store, the bubbles take up considerable moisture, so that the headspace 15 is saturated with moisture.
This means that no streaks or incrustations can form on the container walls.
The new device can operate with a substantially higher concentration, and particularly in the self-preservation concentration range, i.e. with Brix values far over 60 - and in practice up to 71 - so that preservation agents or cooling can be completely dispensed with. In addition, with reference to the high syrup concentration, all hygiene requirements are satisfied, even over long storage and operation periods.
Further details of the new process and the storage and metering device used therein may be obtained from US-PS 3 258 166, in which the control of the metering device is described in greater detailO
In known automatically operating drink preparation apparatus, the carbonated water is fed from the rising pipe 25 of the device shown in Figure 2 and the syrup is fed through the rising pipe 6 of the device shown in Figure 4 each under pressure to a mixing and dispensing head, one embodiment of which is shown diagrammatically in Figure 6.
The mixing and dispensing head H shown in Figure 6 comprises two separated pressure lines which end directly under the head in a mixing zone in the form of nozzles, namely S' for the syrup and S'~ for the carbonated water, which converge 1~38345 towards each other in the exit direction. By means of a con-trol device, not shown, the water and syrup emerge simultane-ously through the converging nozzles under pressure, so that the mutually meeting streams produce a strong turbulence and corresponding mixing. The strongly agitated drink enters the drinking cup 35 disposed under the dispensing head H, a large part of the carbon dioxide escaping into the headspace 36 in the form of foam, as shown by the arrow. As the drink is usually only coarsely impregnated, a large part of the remain-ing carbon dioxide gas escapes quickly after the initial calm-down, so that the drink quickly loses its drinking quality.
In the process according to the invention, which may be carried out in a device as shown in Figures 7 to 9, the carbon dioxide-containing water emerges into the device 34 at one end of the shallow inclined trough 38 with simultaneous pressure reduction in the device 34. Any larger bubbles which may be contained in the water are liberated by the pressure reduction and can rise in the water stream flowing in the direction of the arrow 38c on the floor 38b of the trough.
The water stream 38d covers practically the whole length of the trough along its way and emerges at 40 from a relatively wide exit, and thus practically without any nozzle or jet effect, in the direction of the arrow 40a into a drinking cup 42. The space 38a above the water stream is in pressure equilibrium with the surrounding atmosphere. This means that with a gauze-type closure of the exit 40, the trough is satisfactorily screened hygienically against the surrounding atmosphere. The outlet port of the metering device 13 of the storage container 10 for the highly concentrated syrup lies directly above the water stream 38d. The syrup has a suffic-ient sugar content for its self-preservation, so that cooling of the syrup in the storage container 10 is neither necessary nor desirable. on actuating the metering device 13 the syrup emerges with low static pressure from its lower port, which is indicated in Figure 8 by 13a.
The metered syrup quantity drops into the water stream and produces therein a sudden liberation of part of the carbon dioxide because of the large temperature difference between the syrup and the cooled carbon dioxide-containing water, this having an explosion-type action at the syrup inlet polnt indicated by 39a, and which mixes the syrup with the water almost instantaneously and in spite of its high viscosity, without the syrup being able to deposit on the flat inclined floor 38b of the trough 38. Simultaneously the mixed temperature of the syrup and water mixture rises, e.g. from a temperature of between 0 and 2C of the cooled water to a drinking temperature of about 5C of the finished drink. As the water is enriched with carbon dioxide to its saturation level because of the low temperature, a part of the carbon dioxide is automatically liberated by the temperature rise as the saturation level at the higher drinking temperature is correspondingly lower. The intensive and homogeneous mixing of the water and flavouring substance is attained almost exclusively by the liberation of a determined portion o~ the carbon dioxide. Moreover as the water is finely impregnated with carbon dioxide, there is no danger of more than that portion of carbon dioxide determined by the temperature rise being liberated from the water. This means that the finished drink is nearly at its maximum posible degree of saturation with carbon dioxide corresponding to the drinking temperature of the drink, i.e. to a temperature of approximately 5C.
As the mixed drink flows from the trough 38 at 40 through a relatively large gauze-type opening, only small tur-bulence arises during the outflow. Thus only a small amount of carbon dioxide is liberated during the outflow. As the drink is very finely impregnated with carbon dioxide and almost saturated, it still possesses excellent drinking qualities even after standing for a long period, this also being due to its relatively low temperature. The relatively low temperature is the result of the small water content of the syrup, and thus the relatively low proportion of syrup in comparison with the proportion of carbonated cooled water.
The given values are naturally only examples, typical of a preferred embodiment of the new process. The quantities of carbon dioxide-containing water illustrated in Figures 7 to 9 are obviously shown exaggerated in order to make the illus-tration clearer. In any case it is however desirable to dispose or control the different devices such that the floor 38b ot the trough 38 is covered before and after the addition of syrup with syrup-free water, so that the floor is reliably cleaned with pure water. The floor 38 is in practice the only part of the device which requires occasional cleaning. On this account the trough is desirably transparent and easy to take out. The trough also desirably consists of a material of low thermal conductivity, so that on contact of the cooled water with the warmer floor 38b of the trough, the water warms up only a small amount, with a correspondingly small liberation of carbon dioxide. If syrup residues deposit on the trough floor, no hygiene problems arise as the syrup is practically water-free and therefore self-preserving. In the described explosion-type liberation of carbon dioxide at the point 39a where the syrup drips in, with the given values about 10% of the impregnated carbon dioxide gas is liberated over a period of one second and is limited to the dropping-in region 39a.
As the syrup delivery operation and the mixing take place practically pressureless, large outlet cross-sections may be used for all openings, so that in spite of the pressureless mixing the delivery operation takes place quicker than in systems operating under pressure. The necessary drink volume for de-livery is therefore available after a few seconds.
A preferred embodiment of the water preparation device is shown in Figures 10 and 11. This preparation device consists of a pressure~tight tank 50, in which a water volume 52 is con-tained. The level of the water surface 53 in the tank 50 iscontrolled by a corresponding level detecting element 72 by way of a central control instrument, not shown. The control instru-ment controls a solenoid valve 66 through which water is fed under pressure through the line 67 into the headspace 51 of the tank. The feed takes place under pressure in such a manner that the fed water creates no turbulence. For this purpose, the feed pipe 67 ends in an atomising head 58, which atomises the fed water, the mist or spray depositing on the water surface. The ; 1a38345 low temperature of the water store 52, which i9 between 0 and 2C, preferably a maximum of 1C, is produced in the tank 50 by means of a refrigeration system. This is in the form of a helical evaporator coil 54, connected by its two connectors 55 and 56 to an external cold producer.
The Figures show that the cylindrical evaporator coil 54, which extends over practically the complete height of the water store 52, divides the interior of the tank into two con-centric zones, namely a zone 59 within the evaporator coil and an annular zone 58 outside the evaporator coil. The significance of this form will be discussed further hereinafter.
The interior of the tank 50 is under a predetermined pressure. This pressure is at the same pressure as the carbon dioxide gas, which is fed from a corresponding source through a solenoid control valve 69 to the water store 52. A feed pipe 70 is used for this purpose, which reaches into the water store close to the tank floor 60, its lower end being connected to a ceramic plug or other porous body, through which the carbon dioxide emerges into the water store 52 in very fine bubbles.
This is an important prerequisite for fine impregnation of the water by carbon dioxide.
To prevent the accumulation of clouds of carbon dioxide bubbles, which could both detract from the quality of the soda water and cause formation of larger bubbles and there-with a considerable loss of carbon dioxide in the water, a de-vice is provided to compel practically laminar slow convective flow to take place in the tank. To this end a rotor 61 is supported at the deepest point in the floor 60 of the tank, drawing the water into its center and throwing it outwards in a radial direction over the upward sloping floor. In the illustrated example, the drive is provided externally in a contact-free manner by an external rotatably supported magnet wheel 63, which is driven by the motor 62 and drags the rotor 61 magnetically.
The prepared water may be withdrawn through the line 64 by way of the solenoid control valve 65 and fed to the mixing zone.
When the tank is full and the cooling device in operation, an increasing ice layer forms in the region of the evaporator coil 55, first bridging the interspace between the neighboring pipe turns, so that the evaporator coil 54 together with the forming ice in the tank forms in practice an approxi-mately cylindrical separation wall, which separates the water volume within the evaporator coil 54 flow-wise from the water in the annular zone 58. The convective stream in the water, shown in Figure 11 by the arrow 78, is thus limited to the inner water volume, the stream flows over the floor 60 of the tank and then upwards on the inside of the forming ice wall, and then again to the middle of the water store in the upper region.
The convective stream has several purposes. It prevents the carbon dioxide from forming clouds in the water~ It also assures uniform cooling of the water store, i.e. gives a cer-tain mixing effect. The convective stream also simultaneously serves for controlling the ice wall growing on the cooling coil 54, in that the water stream continuously gives up heat to the ice layer 80 at the inwardly facing ice surface 80c of the forming ice layer 80, and therefore limits the radially inward growth of the ice layer. AS the water is calm in the outer annular zone 58, i.e. there is no convective stream, the ice can grow unhindered in the annular space, i.e. radially outwards, so that a thick layer 80_ forms on the outer circum-ferential surface of the pipe coil 54, while on the inner side of the pipe coil there is only a very thin ice layer 80a. This has the advantage that the thick ice layer 80_ serves as a cold store, while the pipe coil 54 is covered on its inner side with only a thin ice layer, which cannot noticeably hinder the rapid transfer of heat from the water to the pipe coil.
The growth of the ice layer must evidently be con-trolled from the point of view of energy saving and protection of the tank. This is done by corresponding sensors 73, 74, connected into the central control circuit. The evaporator coil 54 can then also be used as an electrode, to form a sens-ing circuit with each of the other electrodes 73 and 74. The outer sensing circuit with the electrode 73 prevents the ice layer growing as far as the tank wall and exerting an unallow-able pressure on the tank. The inner sensing circuit with theelectrode 74 controls, together with the convective stream, the growth of the ice layer 80a on the inner side of the cool-ing coil. In this manner a direct and very effective cooling of the water is obtained, whereby the water assumes a very uniform low temperature. With this arrangement, there is no need to renounce the advantages of an ice layer as a cold store in favor of direct heat transfer from the water to the cooling coil. The arrangement operates particularly economically and may be installed in a very small space. The system operates with practically no maintenance. The produced soda water is constantly of the highest quality and may be directly with-drawn for drinking without any mixing of flavouring substances, giving a previously unknown high C02 content.
As stated, the arrangement also allows the drink to be dispensed through a delivegry opening of large cross-section.
The homogenisation of the dr~nk can therefore be advantageously aided, without producing any other hindering effects, by associating with the delivery opening a gauze through which the drink flows out. The fineness of the gauze is determined inter alia by the actual size of the dispensing opening. It can be easily determined empirically by observing the degree of homo-genisation of the dispensed drink.
The gauze also prevents entry of foreign bodies such as insects into the dispensing opening.
As the control of automatic machines is known as such, and the control functions are clear for the expert from the present description, the illustration and detailed description of the control circuit may be dispensed with.