GB2157963A - Apparatus for dissolving gases in liquids - Google Patents

Abstract

An apparatus for dissolving a gas in a liquid and repeatedly dispensing a fixed volume of the resulting solution is provided comprising: a vessel (4) for mixing the liquid and gas, means (5, 6, 7, 8) for supplying the liquid to the vessel (4), means (2, 3) for supplying the gas to the vessel (4), means for determining the liquid level in the vessel (16), means (19) connected to the liquid level determining means and responsive thereto for activating liquid supply to the vessel (4) if the liquid level is below a first predetermined level (17) so as to raise the liquid level to the first predetermined level (17) but no higher, means (14, 12, 11, 13, 22) for dispensing the resulting solution from the vessel (4) including an outlet valve (14) having open and closed positions, and means (20) connected to the liquid level determining means (16) for adjusting the outlet valve (14) to the open position when the vessel liquid level is at the first predetermined level (17) and for adjusting the outlet valve to the closed position when the vessel liquid level reaches a lower and second predetermined level (18), the volume of the vessel (4) between the first and second predetermined levels being the fixed volume. The invention includes a novel form of carbonator or vessel (4). <IMAGE>

Description

SPECIFICATION Apparatus for dissolving gases in liquids This invention relates to an apparatus for dissolving gases in liquids which is adapted to dispense predetermined volumes of the resulting solution on a repetitive basis. Although the apparatus has application to a wide number of gas/ liquid combinations, the preferred application of the invention is to the carbonation of wine. A new design of gas/liquid dissolving vessel (e.g. a carbonator) is also included.

In the past, the carbonation of still wine has involved the storage and distribution of wine under carbonation in pressurised containers, Carbonated wine was simply dispensed from these containers into the glass at the point of sale. The actual carbonation of the wine was carried out by the supplier inside a bonded warehouse. Such a system has not been commercially successful as a result of high costs involved in pressurised containers and their transportation. In addition to this it is, of course, known to produce carbonated soft drinks using post-mix dispense systems. In such cases, a flavour concentrate is mixed with carbonated water in the required proportions, either by the consumer in the glass or in a dispense valve system.

The development of the present gas/liquid dissolution system was stimulated by a desire to provide an apparatus which would be capable of carbonating a still wine at the sale outlet, wherever that might be, in an accurate manner. Such an apparatus would avoid the necessity for expensive storage vessels and their transport. Such carbonated wine falls under the category of aerated sparkling wine and used to be subject to certain EEC regulations. In particular, these regulations (see Official Journal of the European Communities, 5th March 1979, L54 Volume 22 page No. L54/32) used to stipulate that the carbon dioxide content of the dispensed carbonated wine must not exceed a level which corresponds to the wine having an excess carbon dioxide pressure of 3 bar when at a temperature of 20"C in a closed container.However, maximum customer appeal dictates that a carbonated wine when dispensed should have a relatively high carbon dioxide content. In any event, there is a need for a system which will dispense carbonated wine from a source of still wine but which at the same time ensures that the carbon dioxide content of the dispensed wine is high and accurately determined. Furthermore, there is, however, no known drinks dispense system in which uncarbonated wine passes through e.g. a spray injection type carbonator for the purpose of being carbonated.

The present invention provides an apparatus for dissolving a gas in a liquid and repeatedly dispensing a fixed volume of the resulting solution, comprising a vessel for mixing the liquid and gas, means for supplying the liquid to the vessel, means for supplying the gas to the vessel, means for determining the liquid level in the vessel, means connected to the liquid level determining means and responsive thereto for activating liquid supply to the vessel if the liquid level is below a first predetermined level so as to raise the liquid level to the first predetermined level but no higher, means for dispensing the resulting solution from the vessel including an outlet valve having open and closed positions, arid means connected to the liquid level determining means for adjusting the outlet valve to the open position when the vessel liquid level is at the first predetermined level and for adjusting the outlet valve to the closed position when the vessel liquid level reaches a lower and second predetermined level, the volume of the vessel between the first and second predetermined levels being the fixed volume.

The factors which affect the level of carbonation in any conventional carbonating system are: Carbonation Temperature:- The temperature of the liquid when it is contacted with carbon dioxide in the carbonator. As temperature decreases the level of dissolved carbon dioxide increases.

Carbonation Pressure:-- The pressure of carbon dioxide in contact with the liquid in the carbonator.

At any temperature, as carbonation pressure increases the level of dissolved carbon dioxide increases.

Gas-Liquid Contact Time:- The time that the liquid and carbon dioxide are in contact with each other in the carbonator. This is the carbonator residence time. When a spray injection type carbonator is operating with a continuous liquid feed in and out of the unit, the level of carbonation achieved is between 50% and 75% of the equilibrium value at the carbonation temperature and pressure being used. When this type of carbonator is used to feed liquid directly to a dispense system the flow through the carbonator will be intermittent. In this case liquid is carbonated to between 50% and 75% of the equilibrium value while liquid is being dispensed, but during the time interval between one dispense and the next, when there is no flow, the liquid which is resident in the carbonator continues to absorb carbon dioxide and approaches the equilibrium value.The carbon dioxide level of the liquid which is dispensed from a conventional carbonation system is therefore variable, and dependent on the time interval between one dispense and the next.

In addition, on dispensing the carbonated liquid to a glass the liquid undergoes a rapid reduction in pressure. The effect of this pressure reduction is for the dissolved carbon dioxide to leave the liquid phase and return to its gaseous state.

The apparatus of the present invention is designed particularly to deal with variable carbonation levels (or levels of solution of the gas in the liquid) and, in some embodiments, to deal with the problem of rapid reduction in pressure as the carbonated liquid passes from the apparatus to a glass (in the case of carbonated wine). As indicated the amount of gas which passes into solution depends upon a number of factors. In the case of the carbonation of still wine, pressure, temperature, alcohol content, sugar content and pH of the wine are most important.A typical carbonation pressure for still wine might be from 2 to 5 bar, the carbonation temperature might be from 2"C to 1 5;C and the resulting carbonation level might be from 2 gllitreto 8 g/litre, all depending upon the nature of the original still wine product which is being carbonated.

The Official Journal ofthe European Communities of 14th May 1982, No. L133/78, deals with the question of carbonation of wines and the measurement of degree of carbonation. This reference also sets out the relationship between the various factors, e.g. the quantity of carbon dioxide contained in a sparkling wine, in grams of carbon dioxide per litre of wine, is given by the expression 1.977(1 + 0.987 P) (0.86 - 0.01 A) (1 - 0.00144 S); where: P = the excess pressure of carbon dioxide in the vessel expressed in bars at 20"C, A = the alcoholometric titre at 200C of the wine, and S = the sugar content of the wine in grams per litre.

In the present apparatus, a suitable outlet valve would be a solenoid controlled valve. In addition, a manually operated dispensing valve may be incorporated downstream of the outlet valve, which dispensing valve can optionally be contained within a cowl together with a dispense signalling switch.

Usually, a conduit is provided for carrying gas/ liquid solution to the dispensing valve from the vessel where the solution is formed. This conduit may be provided with a flow regulating device and, downstream of the flow regulating device, means for cooling material passing through the conduit before it reaches the dispensing valve. The advantage of this system is that it avoids the problem noted above of substantial pressure reduction in dispensing a carbonated wine to the glass. Thus, in conventional carbonated drinks dispense systems, a flow regulating valve, which is necessary to control the rate at which a glass is filled, is incorporated into the actual dispense valve.

under these circumstances the carbonated liquid expereiences a rapid reduction of pressure as it flows into the glass. The combination of rapid pressure reduction and turbulence as the liquid flows through the valve, causes dissolved carbon dioxide to be released in the form of small bubbles.

This results in the loss of a large proportion of the carbon dioxide which was dissolved in the carbonator. In contrast, the preferred embodiments of the present invention use a flow regulating device which is separate from the dispense valve and located in pipe work between the vessel carbonator and the means for cooling material passing through the conduit to the dispensing valve. Thus, carbon dioxide released as a result of the reduction in pressure as the liquid flows through the regulating device is maintained in contact with the liquid as it passes through the cooling means. This allows a large proportion of released carbon dioxide to redissolve and thus the overall loss of carbon dioxide during the dispensing operation is considerably reduced compared to prior art systems. The flow regulating device may be a length of smooth small bore tubing built into the conduit.

This is a very efficient means of regulating flow with minimum loss of gas. Alternatively, the device may be a valve.

The cooling means in the dispensing conduit may comprise a portion of the conduit formed as a cooling coil and passing through a refrigerated enclosure. When the flow regulating device is smooth small bore tubing this may form part or all of the cooling coil. If course, it is also preferred that the means for supplying liquid to the vessel for producing the gas-liquid solution includes means for cooling the liquid and this latter means may also be a cooling coil passing through the same refrigerated enclosure. The refrigerated enclosure is preferably thermostatically controlled and, ideally, has a temperature sensor positioned therein associated with means for preventing operation of the apparatus or for switching off power supply to the refrigeration unit of the enclosure when the temperature in the enclosure drops below a preset value.It is preferred that the means for preventing operation of apparatus includes means for preventing the supply of liquid to the vessel if dispensing of solution has not yet started and for preventing the outlet valve from adopting the open position or for closing the outlet valve if dispensing of solution has started. Preferably, the means for supplying liquid to the vessel includes a pump, the operation of which pump is prevented by operation of the means for preventing the supply of liquid to the vessel. Such a temperature monitoring system is a means by which carbonation may be strictly controlled and no such system is in operation in any existing apparatus or is suggested in the art.

A further preferred feature of the invention is that the means for supplying the gas (carbon dioxide, for example) to the vessel includes means for venting gas in the vessel to atmosphere. Thus, it is preferred that the apparatus of the present invention includes means for ensuring that if the volume of solution dispensed is less that the volume of the vessel between the first and second predetermined levels, the supply of gas to the vessel is ended and the gas in the vessel is vented to atmosphere via the venting means following a pre-set period of time.

Furthermore, the vessel may be equipped with a pressure release valve adapted to open if gas pressure therein exceeds a predetermined value.

The gas venting means and the pressure release means valve may, of course, be the same structure.

Thus, in the most preferred embodiments of the invention, the invention provides an apparatus in which the volume of liquid (e.g. still wine) is strictly controlled and fixed volumes repeatedly dispensible, the temperature and pressure in the solution-forming vessel are strictly controlled, and the unusual position of the flow regulating device before a secondary cooling means such as a cooling coil, ensures the minimum loss of gas from solution at the point of dispensing. The present apparatus permits the sequencing of carbonation and dispensing operations in a wine carbonation system to be such that only a small and consistent volume of liquid remains in the vessel/carbonator between use of the equipment. This achievement is entirely dependent upon the linking of the predetermined levels in the vessel (high and low levels) to the opening and closing of the vessel outlet valve.

The invention also includes a vessel suitable for use in the present apparatus comprising an upper chamber provided both with means for supplying the gas thereto and a spray nozzle inlet for supplying the liquid thereto, and a lower chamber opening upwardly into the bottom of the upper chamber through an aperture which is appreciably smaller than the cross-sectional size of the upper chamber.

In another aspect the invention provides a vessel for dissolving a gas in a liquid comprising an upper chamber provided both with means for supplying the gas thereto and a spray nozzle inlet for supplying the liquid thereto, and a lower chamber opening upwardly into the bottom of the upper chamber and having a cross-sectional size appreciably smaller than the cross-sectional size of the upper chamber, The aforesaid two aspects of the invention provide a wholly new concept in, for example, carbonator.

Of course, although the present invention is described with reference to a wine carbonation system, it is envisaged that the apparatus can be applied, with such consequential modifications as are apparent to the skilled man, to any gas/liquid dissolving system. Thus, one possible use of the apparatus of the present invention is for chlorinating and dispensing water, i.e. as a water purification unit.

The invention will now be further described and illustrated (but not necessarily limited) by reference to the accompanying drawings, in which: FIGURE lisa schematic diagram of a wine carbonation and dispense system in accordance with the invention; FIGURES 2A, 2B, 2C and 2D are curcuit diagrams forthecontrol of a system as shown in FIGURE 1; FIGURE 3 is a flow sequence showing the operation of a system as illustrated in FIGURE 1; and FIGURE 4 shows a new carbonator in accordance with the invention.

The apparatus in accordance with the invention shown generally by reference numeral (1), comprises a supply of carbon dioxide (2) leading via a valve (3) to a carbonator or gas/liquid mixing vessel (4). Also leading into vessel (4) is a conduit (5) conveying still wine from a supply (6). In its passage from supply (6) to vessel (4), the still wine passes through a feed pump (7) and a primary cooling coil (8). Coil (8) is immersed in a cooling bath (9) which is powered by a conventional regrigeration unit (10).

Leading from vessel (4) via an outlet solenoid valve (14) is a dispensing conduit (11 ) which incorporates a flow regulating device (12).

Downstream of device (12) is a secondary cooling coil (13) which is immersed in the same cooling bath (9) as coil (8). Conduit (11 ) then leads to a manuallyoperated dispensing valve (22) for dispensing of carbonated liquid into receiver (15) (e.g. a glass).

Vessel (4) is associated with a sensing means (16) which is preset to determine a high liquid level (17) and a low liquid level (18) in the vessel. The volume of the vessel (4) between the high and low levels is the desired volume of carbonated wine for dispensing purposes during a single dispensing operation. Sensing means (16) feeds back information to a control module (19) which is provided with a control connection (20) to outlet valve (14).

Control module (19) also receives information from a temperature sensor (21) in cooling bath (9) and can, if desired, automatically switch off refrigeration unit (10) when the temperature of cooling bath (9) measured by sensor (21) is below a preset value. Alternatively, or in addition, a control connection (23) can switch off pump (7) or control connection (20) closes valve (14) or inhibits its opening when the temperature of cooling bath (9) measured by sensor (21) is below a preset value.

This temperature monitoring function thus can, if desired, inhibit the carbonation and dispense operation entirely if temperature goes below a certain preset value. This is a useful way of preventing over-carbonation of wine.

Gas supply valve (3) includes a vent to atmosphere which provides a pathway for excess gas pressure to leave vessel (4) to the atmosphere if necessary.

The sequencing of carbonating and dispensing operations with respect to the present apparatus for the carbonation of a still wine allows the achievement of the maximum level of dissolved carbon dioxide in the wine whilst eliminating the possibility of carbonating above the maximum allowable level. The sequence of events leading to dispensing of a single glass of carbonated wine may be carried out automatically under the control of module (19) and is initiated by an electrical signal originating from the point of dispense, e.g. the pressing of a button (not shown).

The sequence of operation begins by an examination of the actual liquid level in vessel (4) using sensing means (16). If this is below high level (17) carbonatorfeed pump (7) is started and continues to run until the level of liquid in vessel (4) reaches high level (17) when the pump is automatically stopped. As the feed pump stops, there is (as described with reference to Figure 2D) automatic activation of the solenoid outlet valve (14) by connection (20) putting the valve in the open position and allowing carbonated wine to flow to the dispensing valve (22) and into glass (15). Outlet valve (14) closes again once the liquid level in vessel (4) has returned to low level position (18). This completes the carbonation and dispensing sequence. During this sequence a supply of carbon dioxide (2) is maintained to vessel (4) through control valve (3).

In the event of the above sequence being interrupted for any reason whatsoever the supply of carbon dioxide (2) to vessel (4) is shut off by the closing of valve (3) and carbon dioxide in vessel (4) may be vented to the atmosphere through valve (3).

The normal condition at the start of a carbonation dispensing sequence is that residual liquid in vessel (4) is at the low level position (18). This level is predetermined to correspond to a liquid volume in the vessel (4) which is only a very small proportion of the volume that is actually dispensed into a glass.

Naturally, during the period of time since the previous dispensing of a glass of carbonated wine, the residual liquid in vessel (4) will have absorbed carbon dioxide and will in fact have achieved a higher carbon dioxide content. When carbonator feed pump (7) commences its operation, freshly carbonated wine at a lower carbon dioxide content mixes with this. When the high level (17) in vessel (4) is reached, pump (7) stops as described with reference to Figure 2A. The contents of vessel (4) may be emptied by the means already described into a receiving glass (15). Carbonation conditions, i.e. temperature and pressure, are such that the resulting carbon dioxide content of the dispensed wine does not exceed the maximum legal or desired value.This is adjusted to be the case even allowing for residual liquid in vessel (4) to reach its equilibrium carbon dioxide content.

Of course, the system described allows for automatic volume dispensing of carbonated wine since the outlet valve (14) is opened and closed at the high and low level positions (17, 18) in vessel (4) as described with reference to Figure 2D. The relative positions of these levels are set to correspond to the average volume of a wine glass or other desired vessel for receipt of the dispensed wine.

If, for any reason, the volume of wine dispensed from vessel (4) is less than the volume between high level (17) and low level (18), overcarbonation of the resulting larger than usual residual volume of liquid in vessel (4) is avoided by the termination of the supply of carbon dioxide (2) to the vessel and the venting of carbon dioxide in vessel (4) to the atmosphere through valve (3). This will occur automatically if the low level position (18) is not reached within a specified period of time, and is achieved by the use of timers, as described with reference to Figure 2C.

In operation of the apparatus, the actual carbon dioxide content of the dispensed carbonated wine may be chosen to allow for maximum control variations in temperature and pressure for the components of the apparatus. As further safeguards, the temperature monitoring system involving the use of sensor (21) referred to above (preferably as a back up for a standard cooling bath thermostat control, not shown in FIGURE 1) allows the temperature of carbonation to be controlled and a pressure release may be provided by fitting vessel (4) with a pressure release valve (not shown) set to open if the pressure in the vessel exceeds a predetermined value.

Furthermore, the positioning of flow regulating device (12) upstream of cooling coil (13) ensures, in the manner previously described, that the carbonated wine passing through dispensing valve (14) retains the maximum possible amount of carbon dioxide and minimises loss of carbon dioxide during the dispensing into the glass.

In a typical operation, the filling time for vessel (4) might be three to four seconds and the dispensing time ten seconds. A typical period of time for the overall carbonation and dispensing operation would be twenty seconds from the activation of the system. This is in effect the "residence time" of wine in contact with the carbon dioxide and is, of course, of importance in determining the carbonation level.

The contact time between gas and liquid in vessel (4) is limited to a maximum value such that overcarbonation cannot occur. This is achieved using a timer (Figure 2D) which causes gas to be automatically vented if a pre-set period of time is exceeded between initiation of the dispense operation and sensing of the low level (18).

The individual items of equipment used in producing an apparatus as shown in FIGURE 1 may be conventional items well known in the art, e.g.

items used extensively in soft drink or still wine dispensing.

Figures 2A to 2D are schematic diagrams of circuits for controlling the system shown in Figure 1.

These circuits are, in this particular embodiment, based on the use of standard type 555 integrated circuits (as made by, for example, Signetics Corporation), the type 555 circuits having their external pins appropriately connected (in accordance with normal practice) to provide the particular mode of operation required.

Figure 2A is a diagram of the circuit for controlling the motor of the feed pump 7. The circuit has two type 555 circuits 100 and 101. The circuit 100 has a control input 102 which is enabled on operation of the dispense push button to provide a three second delay, adjustable by means of a potentiometer 103.

The second type 555 circuit 101 provides energisation of a relay coil 104 which controls two sets 105 and 106 of relay contacts. Each set of contacts has a central movable contact and two fixed contacts. The set 105 of contacts normally provides an open circuit between a line 107 to a terminal of a motorforthe pump 7 and a power supply line 108, the lines 107 and 108 being connected, to cause energisation of the pump motor, when the relay coil 104 is energised. The contact set 106 operates in correspondence with the set 105 and is operative to couple either the green light emitting diode 109 (when the pump is operating) orthe red light emitting diode 110 (when the relay is de-energised) to the supply line 111. A further control input 112 from the sensor which senses the high level of liquid in the carbonator 4 controls pin 4 of the pump driver circuit 101.The connection between the pump driver and the relay coil 104 extends through a pair of terminals 113 which are rendered open circuit by the operation of the pump protection circuit shown in Figure 2B, which will be described later.

As mentioned earlier, the purpose of the pump control circuit is to start the pump when the dispense button is pressed and to stop the pump when the liquid has reached the predetermined level associated with the high level probe in the carbonator 4.

When the dispense button is pressed, a logic signal from input 102 is supplied to pin 2 of the circuit 100. The timer in this circuit is started and after a delay of approximately three seconds, which may be adjusted by the potentiometer 103, a pulse from pin 3 of circuit 100 is routed to pin 2 of the pump driver circuit 101, which energises the relay coil 104. The closure of the left hand pair of contacts in the set 105 energises the pump motor so that the pump starts and liquid is pumped to the carbonator until the level of liquid in the carbonator reaches the level associated with the high level sensor.

Thereupon a signal from that sensor appears on pin 4 of the pump driver circuit 101, which de-energises relay coil 104 to open the connection between lines 107 and 108 and thereby stops the pump. If the signal on pin 4 of the pump driver circuit 101 is already present when the dispense button is pressed, the pump will not start, since the existence of this signal indicates that the liquid in the carbonator 4 is already at the high level.

Figure 2B is a diagram of the pump protection circuit. This includes a 555 type circuit connected as a one shot with a thirty second timing period (adjustable by means of a potentiometer 123). The circuit 120 enables a second type 555 circuit 121 which drives a relay coil 124. This relay coil controls two sets of contracts 125 and 126. The contacts 125 provide, on closure of the left hand pair in the set connection of the terminals 113 between the pump driver 101 and the relay of the coil 104 in Figure 2A.

In the set of contacts 126 the right hand pair are normally closed to energise a red light emitting diode 130. This diode is off while the pump is operating and comes on when it stops.

A line 102a enabled on operation of the dispense button is connected to pin 2 of the circuit 120 and lines 112a and 112b are coupled to pins 4 of the circuits 120 and 121 respectively; these lines 112a and 11 2b are enabled when the respective sensor senses liquid at the high level in carbonator 4.

The pump protection circuit is provided to inhibit the operation of the pump as a safeguard against the emptying of the wine container 6 and thereby to prevent the pump from running dry.

When the dispense button is pressed, the signal on line 102a is applied to pin 2 of circuit 120. Circuit 120 enables the driver 121 to energise relay 124, thereby to close terminals 113. After the adjustable delay (approximately thirty seconds) of the delay circuit 120, the timer therein will time out to disable driver 121, which will de-energise coil 124 and open circuit terminals 113, thereby preventing further operation of the pump. This occurs if a signal from the high level probe has not been received at pin 4 of the driver circuit 121. Under normal operation however a signal from the high level sensor is received within approximately ten seconds of the starting of the pump and the signal on line 1 12a is applied to pin 4 of circuit 120 in order to reset the timer therein to zero ready for the next start signal.

Figure 2C is a diagram of the circuit for controlling the gas control valve that controls the flow of carbon dioxide into the carbonator 4. The circuit includes a type 555 circuit constituting a relay driver 131, arranged when enabled to energise relay coil 134 that controls two contact sets 135 and 136. The set 135 has the right hand pair of contacts normally closed and the left hand pair normally open; on closure of the left hand pair in response to energisation of coil 134 a line 137 to a solenoid for the gas control valve is connected to supply line 138 in order to energise the solenoid and to open the valve. When the valve is closed (to stop the supply of carbon dioxide to the carbonator 4), the valve vents the carbonator 4 to atmosphere. The (normally open) left hand pair of contacts of set 136 energise, when closed, a light emitting diode 139 from a supply line 141.Normally, the right hand pair of contacts couple light emitting diode 140 to the supply line 141. Light emitting diode 139 illuminates when carbon dioxide is being supplied through the valve whereas light emitting diode 140 illuminates when the supply of carbon dioxide is cut off.

On the operation of the dispense button, line 102c is energised to enable pin 2 of the relay driver 131, which energises coil 134 and causes opening of the carbon dioxide supply valve. The internal timer of the relay driver is started; the timing period of the timer is adjustable by means of potentiometer 132.

The valve will stay open while the equipment is in operation and does not require resetting each time the dispense button is pressed, unless the timer is circuit 131 times out. The timer is incorporated to ensure that if liquid remains in the carbonator for a set time, for example, five minutes, the supply of carbon dioxide is cut off and any remaining carbon dioxide in the carbonator is vented to a predetermined pressure, for example 1 psi.

The low level sensor controls line 133 which is coupled to pins 6 and 7 of the relay driver circuit 131.

If a signal from the low level sensor has not been received on those pins to signify that the liquid has been dispensed after the set time (five minutes) the timer times out and the relay coil 134 is deenergised, to close the supply valve and to vent the carbon dioxide in carbonator 4. The signal on line 133 resets the timer to zero so that the relay driver is not enabled again until the dispense button is pressed.

Figure 2D is a diagram of the circuit for controlling the outlet valve 14 of Figure 1. In the circuit of Figure 2D, a type 555 circuit 142 constitutes a driver for a relay coil 144 which controls two sets of contacts 145 and 146. The contacts 145 provide normally an open circuit between an electrical supply line 148 and a line 147 to a solenoid controlling the valve 14.

The contact sets 146 provide for energisation of either the light emitting diode 149 (when the dispense valve solenoid is energised) or the light emitting diode 150 (when the dispense solenoid is de-energised). The low level sensor enables line 133a which is connected to pin 4 of the driver circuit 142.

The circuit of Figure 2D is provided to ensure the outlet valve 14 only opens when liquid has reached a predetermined level in the carbonator 4. While the liquid is at the low level, the relay coil 144 is deenergised because a signal is present on pin 4 of circuit 142. As the pump 7 raises the liquid level in the carbonator the high level sensor is activated, to provide a signal on line 112c, enabling pin 2 of driver 142 so as to energise coil 144 and thereby to open the outlet valve 14. As liquid is dispensed, the level of liquid in carbonator 4 falls. When the liquid level reaches the predetermined low level, the line 133a controlled by the low level sensor is activated and the driver (constituting in this circuit a bi-stable) de-energises relay coil 144 to close the valve.

Accordingly, the circuit provides, in combination with the sensors for the high level and low level of liquid a means for dispensing a predetermined volume of liquid.

The particular construction of the sensors is not essential to the present invention but it is convenient to provide a pair of probes, which act as electrodes in the liquid and are of the resistive type.

For example, an electrode may be common to both the high level probe and the low level probe so that if no liquid is present between the common electrode and the high level or low level probe a high resistance is seen by an associated control circuit; if liquid is present a low resistance is seen by the control circuit. The control circuit (not shown) provides the signals on the various lines 112 to 11 2c and lines 113 and 113a.

Naturally, a control module based upon solid state components and circuit boards is preferred.

The control sequence is, of course, ideally designed with a maximum running time for operation of feed pump (7) and foroutletvalve (14) to be opened.

The manner of operation and control of the apparatus of the present invention shown in Figure 3 is largely self-explanatory. It will, however, be noticed that the apparatus of the invention desirably incorporates a manual reset facility as an additional precaution against faulty operation. Furthermore, the use of preset running times for the feed pump (7) and the operation of outlet valve (14) provide additional precautions to prevent over-carbonation.

The design of vessel or carbonator (4) is quite important and the carbonator (27) illustrated in Figure 4 has been designed specifically for use with the wine carbonation and dispense system as described above. Carbonator (27) may be made from stainless steel or other suitable material. Wine or other liquid to be carbonated (represented by arrow A) is injected via a spray nozzle (24) into an upper, preferably cylindrical, carbonating chamber (25) where it absorbs carbon dioxide. The resulting carbonated wine collects in the lower, preferably cylindrical, carbonated liquid chamber (26) via aperture (28) from where it is fed to the point of dispense via conduit (11) as described above.The carbonator (27) is also fitted with a connection (2) by which carbon dioxide gas under pressure (represented by arrow B) enters the carbonator, and a safety valve (29) for the purpose of relieving excess gas pressure from the carbonator. The carbonator (27) is fitted with a level probe (30) or other means for the purpose of controlling the level of carbonated liquid in the lower chamber between a lower fixed level (18) and an upper fixed level (17).

The liquid which is required to be carbonated enters the upper chamber under pressure via the spray nozzle (24) in the form of a fine spray. As the sprayed liquid falls through the atmosphere of carbon dioxide in the upper chamber (25) it dissolves carbon dioxide and thereby becomes carbonated. The carbonated liquid passes into the lower chamber (26) where it accumulates. When the carbonated liquid has accumulated to the point where the level of liquid has reached the upper fixed level (17) as detected by the level probe (30), the supply of liquid to the carbonator (27) is automatically cut-off.

The carbonator (27) design has the following features which are important to satisfactory operation. First, carbonation takes place in upper chamber (25) and carbonated liquid collects in lower chamber (26). Secondly, as a result of the relatively small diameter of the lower chamber (26) in which the carbonated wine collects, the accuracy and repeatability of the dispensed liquid volume is high.

This is because of the relationship between the level variation and volume variation. In the lower chamber (26) a large variation in liquid level results in a relatively small variation in liquid volume.

Consequently, the normal inaccuracies which are associated with various available means of liquid level sensing result in very small variations in liquid volume. The equipment can be made to function with a dispense volume accuracy and repeatability of better than 150 ml t 2 ml. In a conventional carbonator, having a single diameter of say 10 cm, the volume change for a 1 mm change in liquid level would be 7.85 ml. The corresponding volume change for a 1 mm change in liquid level in the lower chamber (26) of the present carbonator (27) where the diameter would typically be 3 cm is 0.71 ml. This meansthatthevolumeofcarbonated liquid between the high and low level positions can be more accurately controlled than in a conventional carbonator fitted with a level sensing device similar to level probe (30).Thirdly, as a result of the relatively small surface area of liquid in the lower chamber (26) which is in contact with the gas during its residence in the carbonator (27), the rate at which carbon dioxide continues to be absorbed is extremely slow. This further avoids the risk of wine being carbonated above a maximum desired level.

No known previous carbonator design embodies the above considerations and the invention includes the new design.

Preferably, the diameter of aperture (28) is 1/3 or less the diameter of the diameter of upper chamber (25). Similarly, it is preferred that the diameter of lower chamber (26) is 1/3 or less of that of upper chamber (25).

It will be appreciated that the present inventive concept includes as a further aspect a method for dissolving gas in a liquid and repeatedly dispensing a fixed volume of the resulting solution comprising supplying the liquid and gas to a vessel so that the liquid level in the vessel reaches a first predetermined level but no higher, permitting the gas to dissolve in the liquid, and dispensing the resulting solution from the vessel until the liquid level reaches a second and lower predetermined value but no lower, the volume of the vessel between the first and second predetermined levels being the fixed volume, and the supply of liquid to the vessel and dispensing of the resulting solution being operationally linked to the vessel liquid level so that supply of liquid to the vessel occurs when dispensing is initiated if the vessel liquid level is below the first predetermined level and dispensing ceases when the vessel liquid level has decreased to the second predetermined level.

The skilled man will readily appreciate that the present invention may be embodied in many different ways and adapted to suit particular circumstances or modified for special purposes.

Such apparent adaptations and modifications are, of course, included within the scope of the invention.

Claims (29)

1. An apparatus for dissolving a gas in a liquid and repeatedly dispensing a fixed volume of the resulting solution, comprising a vessel for mixing the liquid and gas, means for supplying the liquid to the vessel, means for supplying the gas to the vessel, means for determining the liquid level in the vessel, means connected to the liquid level determining means and responsive thereto for activating liquid supply to the vessel if the liquid level is below a first predetermined level so as to raise the liquid level to the first predetermined level but no higher, means for dispensing the resulting solution from the vessel including an outlet valve having open and closed positions, and means connected to the liquid level determining means for adjusting the outlet valve to the open position when the vessel liquid level is at the first predetermined level and for adjusting the outlet valve to the closed position when the vessel liquid level reaches a lower and second predetermined level, the volume of the vessel between the first and second predetermined levels being the fixed volume.

2. An apparatus as claimed in claim 1, wherein the outlet valve is solenoid-controlled.

3. An apparatus as claimed in claim 1 or claim 2, wherein the solution dispensing means also includes a manually operated dispensing valve positioned downstream of the vessel outlet valve.

4. An apparatus as claimed in claim 3, wherein a conduit is provided for carrying gas/liquid solution to the dispensing valve from the vessel, the conduit being provided with a flow regulating device and downstream of the flow regulating device means for cooling material passing through the conduit before it reaches the dispensing valve.

5. An apparatus as claimed in claim 4, wherein the cooling means comprises a portion of the conduit formed as a cooling coil and passing through a refrigerated enclosure.

6. An apparatus as claimed in any one of claims 1 to 5, wherein the means for supplying the liquid to the vessel includes means for cooling the liquid.

7. An apparatus as claimed in claim 6 when dependent upon claim 5, wheein the means for cooling the liquid comprises a cooling coil passing through the said refrigerated enclosure.

8. An apparatus as claimed in claim 5 or claim 7, wherein the refrigerated enclosure is thermostatically controlled.

9. An apparatus as claimed in any one of claims 5, 7 or 8, wherein the refrigerated enclosure has a temperature sensor positioned therein and is associated with means for preventing operation of the apparatus if the temperature in the enclosure sensed by the sensor drops below a predetermined value.

10. An apparatus as claimed in claim 9, wherein the means for preventing operation of the apparatus includes means for preventing the supply of liquid to the vessel if dispensing of solution has not yet started and for preventing the outlet valve from adopting the open position or for closing the outlet valve if dispensing of solution has started.

11. An apparatus as claimed in claim 10, wherein the means for supplying liquid to the vessel includes a pump, the operation of which pump is prevented by operation of the means for preventing the supply of liquid to the vessel.

12. An apparatus as claimed in claim 5 or in any one of claims 7 to 11, wherein the refrigerated enclosure has a temperature sensor positioned therein and is associated with means for switching off power supply to the refrigerated unit of the refrigerated enclosure if the temperature in the enclosure sensed by the sensor drops below a predetermined value.

13. An apparatus as claimed in any one of claims 1 to 12, wherein the means for supplying the gas to the vessel includes means for venting gas in the vessel to atmosphere.

14. An apparatus as claimed in claim 13 including means for ensuring that if the volume of solution dispensed is less than the volume of the vessel between the first and second predetermined levels the supply of gas to the vessel is terminated and gas in the vessel is vented to atmosphere via said venting means.

15. An apparatus as claimed in any one of claims 1 to 14, wherein the vessel is equipped with the pressure release valve adapted to open if gas pressure therein exceeds a predetermined value.

16. A vessel for dissolving a gas in a liquid comprising an upper chamber provided both with means for supplying the gas thereto and a spray nozzle inlet for supplying the liquid thereto, and a lower chamber opening upwardly into the bottom of the upper chamber through an aperture which is appreciably smaller than the cross-sectional size of the upper chamber.

17. A vessel as claimed in claim 16, wherein the aperture and the cross-section of the upper chamber are substantially circular, the ratio of the diameter of the aperture to the diameter of the upper chamber being a maximum 1:3.

18. A vessel for dissolving a gas in a liquid comprising an upper chamber provided both with means for supplying the gas thereto and a spray nozzle inlet for supplying the liquid thereto, and a lower chamber opening upwardly into the bottom of the upper chamber and having a cross-sectional size appreciably smaller than the cross-sectional size of the upper chamber.

19. A vessel as claimed in claim 18, wherein the upper and lower chambers are substantially circular in cross-section, the ratio of upper to lower chamber diameter being a minimum of 3:1.

20. A vessel as claimed in any one of claims 16 to 19 which is a carbonator.

21. A vessel for dissolving a gas in a liquid substantially as hereinbefore described with reference to and as illustrated in Figure 4 of the accompanying drawings.

22. An apparatus as claimed in any one of claims 1 to 15, wherein the vessel is a vessel as claimed in any one of claims 16 to 21.

23. An apparatus as claimed in claim 1 and substantially as hereinbefore described.

24. An apparatus for dissolving a gas in a liquid and repeatedly dispensing a fixed volume of the resulting solution substantially as hereinbefore described with reference to and as illustrated in Figure 1 or Figure 1 as modified by any one or more of Figures 2(a), 2(b), 2(c), 2(d) or 4 of the accompanying drawings.

25. A method for dissolving a gas in a liquid and repeatedly dispensing a fixed volume of the resulting solution comprising supplying the liquid and gas to a vessel so that the liquid level in the vessel reaches a first predetermined level but no higher, permitting the gas to dissolve in the liquid, and dispensing the resulting solution from the vessel until the liquid level reaches a second and lower predetermined value but no lower, the volume of the vessel between the first and second predetermined levels being the fixed volume, and the supply of liquid to the vessel and dispensing of the resulting solution being operationally linked to the vessel liquid level so that supply of liquid to the vessel occurs when dispensing is initiated if the vessel liquid level is below the first predetermined level and dispensing ceases when the vessel liquid level has decreased to the second predetermined level.

26. A method as claimed in claim 25, wherein the gas is carbon dioxide.

27. A method as claimed in claim 25 and substantially as hereinbefore described.

28. A method as claimed in claim 25 and substantially as hereinbefore described with reference to the accompanying drawings, FIGURE 3 in particular.

29. A carbonated beverage, e.g. carbonated wine, which has been produced by the use of an apparatus as claimed in any one of claims 1 to 15 or 22 to 24 or a method as claimed in any one of claims 26 to 28.