Abstract:
A gas reclamation system for use in a beverage dispensing system. The system includes a valve for releasable connection to a used beverage container containing a pressurized gas, the valve allowing release of gas from the container. A filter for removal of particulate matter from the gas and a sterilizer for removal of bacteria from the gas are also provided, together with a compressor to re-pressurize the filtered and sterilized gas for supply to the beverage dispensing system. The system may be used for carbon dioxide recovery from beverage containers, reducing the consumption of carbon dioxide from beverage dispensing systems.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a gas reclamation system, particularly but not exclusively to a gas reclamation system for use in recovering carbon dioxide or other gases from kegs containing pressurized beverages. 
     BACKGROUND 
     Draught beverages such as lager and bitter beers, cider and stout are served in bars using pressurized systems. The beverage is supplied to the bar in kegs and is pressurized with carbon dioxide or a mixture of carbon dioxide and nitrogen. This “top pressure” may be up to 2.81 kg cm −2  (40 p.s.i.) in the case of lager beers. The latest approach to dispensing such beverages has a requirement for even higher top pressures. In order to maintain the pressure in the keg at an approximately constant level, carbon dioxide and optionally nitrogen is pumped into the keg as the beverage is supplied to the consumer. If the pressure in the keg dropped, carbon dioxide would be allowed to escape from the beverage during storage, creating foaming or fobbing of the beverage, which is undesirable. The additional carbon dioxide is supplied from bottles that are attached to the bar&#39;s dispensing system. 
     Kegs that have been emptied of liquid (and are hence full of pressurized gas) are returned to the brewery from the bar, where they are vented to atmosphere before being re-filled with beverage. This venting constitutes a significant source of carbon dioxide emissions, and as CO 2  is a “greenhouse” gas it is therefore desirable to reduce the amount of these emissions to a minimum. In addition, in order to fill the kegs with carbon dioxide, the bar must regularly purchase or lease bottles of CO 2 , which are expensive. There is also in environmental impact from the supply of the bottles to different bars, as there are exhaust emissions from the delivery trucks. 
     It is an object of the present invention to obviate or mitigate these disadvantages with prior art systems, and to provide a gas reclamation system to lessen the need for supplying large quantities of carbon dioxide to run beverage dispensing systems in bars. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a gas reclamation system for use in a beverage dispensing system comprising a coupler for releasable connection to a used beverage container containing a pressurized gas, the coupler allowing release of gas from the container, and a compressor connected to the coupler and arranged to pressurize released gas for supply to the beverage dispensing system. 
     Preferably, a gas sensor, a pressure sensor, a filter, and a sterilizer are provided upstream of the compressor. The sterilizer may comprise an ionizer and a de-ionizer. Optionally a collecting tank may be provided upstream of the compressor, or one or a plurality of collecting tanks may be provided downstream of the compressor. A separator may also be provided to separate different gases, one of which is passed to the compressor. This may be used if the gas in the container is a mixture of gases such as nitrogen and carbon dioxide. Alternatively different gases/gas mixtures may be selectively delivered to different collection tanks. 
     One or more of the above components may be under the control of a central processing unit. In this way collection of the gas being reclaimed may be automatically regulated (e.g. delivered to an appropriate collection vessel). 
     The gas to be reclaimed may be carbon dioxide. The gas reclamation system according to the present invention reduces the amount of carbon dioxide that is used in beverage dispensing systems, and thus reduces harmful CO 2  emissions to the atmosphere. The reduction in consumption of CO 2  also means that the cost of running a beverage dispensing system is substantially reduced. 
     According to a second aspect of the present invention there is provided a beverage dispensing system comprising a gas reclamation system according to any preceding claim, a dispensing coupler for connection to a container from which a beverage is to be dispensed, and a gas supply line connected to the dispensing coupler to supply pressurised gas to the container, the compressor being connected to supply pressurised gas to the gas supply line. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic illustration of a prior art beverage dispensing system; 
         FIG. 2  is a schematic illustration of a gas reclamation system according to the present invention; 
         FIG. 3  is a schematic illustration of a beverage dispensing system incorporating the gas reclamation system of  FIG. 2 ; and 
         FIG. 4  is a schematic illustration of a second embodiment of a gas reclamation system according to the present invention 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1  of the accompanying drawings, there is illustrated a prior beverage dispensing system comprising a plurality of kegs  1 , each connected to a keg coupler  2  provided with two valves  3 ,  4 . One of the valves  3  of each keg coupler  2  is attached to a line  5 . Each line  5  is attached at its other end to a dispense head gas pump  6  which is powered using compressed air, which is typically provided on a bar to dispense draught beverages, and may be provided some distance from the remainder of the beverage dispensing system, including the kegs, which may typically be placed in a cellar of the bar. 
     The valves  4  of the keg couplers  2  are each connected to a line  7  that is attached at its other end to a valve  8  provided on a gas ring main  9 . A carbon dioxide supply bottle  10  is also attached to the gas ring main  9 . 
     A compressor  11  is attached to an air ring main  12 , and supplies pressurized air to the air ring main  12  via valves  13  and  14  in order to drive the dispense heads  6 . The gas bottle  10  is also connected to the valve  13  via line  15 , the valve  13  being arranged to supply carbon dioxide to the dispense heads from the gas bottle  10  in the event that the air compressor fails. 
     As beer or another beverage is dispensed from dispense heads  6 , carbon dioxide from supply bottle  10  is used to maintain a roughly constant top pressure in the kegs  1 . As a result, once all the beverage within a keg has been dispensed, the keg is full of pressurized carbon dioxide. The bottle  10  must be changed frequently as the carbon dioxide is used up. 
     Referring now to  FIG. 2 , a gas reclamation system according to the present invention is illustrated which can be used to recover carbon dioxide from a keg taken from a system such as that shown in FIG.  1 . It comprises an input line attached to a keg coupler  2  for connection to a gas-filled keg  1 , the line feeding to, in sequence, a filter  16 , a steriliser  17 , a separator  18 , a first collection tank  19   a , a food quality compressor  20  and finally to an outlet line  21 . The collection tank  19   a  serves to limit the pressure applied to the inlet of the compressor  20  from the keg  1 . The outlet line  21  could be connected to, for example, a gas storage bottle such as the bottle  10  of  FIG. 1 , but is preferably connected to the gas ring main of the beverage dispense system, as shown in FIG.  3 . 
     The same reference numerals are used where appropriate in  FIGS. 1 ,  2  and  3 . The compressor  20  is provided in a compressor station  22  which also includes a second collection tank  19   b  to receive gas compressed by the compressor  20 . The compressor outlet line  21  is connected to the gas ring main  9  via pressure regulator valve  13 . The gas bottle  10  is also connected to the gas ring main  9  through the valve  13  such that gas is supplied from the bottle  10  only when the compressor  20  and the associated collection tank  19   b  are unable to maintain the required top pressure within the kegs  1  connected to the gas ring main  9 . 
     In the embodiment shown in  FIG. 3 , the pressure required to work the dispense heads  6  is drawn from a separate air ring main (not shown) with its own compressor. A one-way valve (not shown) could be provided from the gas ring main  9  to the air ring main in order to supply carbon dioxide from the gas ring main in the event that there is not enough pressure in the air ring main to power the dispense heads. 
     The use of the system is as follows: 
     Full kegs  1  are connected to the keg couplers  2  that are attached to the dispensing lines  5  and the beverage is dispensed from the heads  6 . As the pressure in a keg  1  falls due to the beverage being dispensed, the valves  4  open to introduce carbon dioxide into the keg  1  from the gas ring main  9  in order to keep the pressure within the keg within predetermined levels. 
     Once all the beer or other beverage has been dispensed from the keg, and the keg is full of carbon dioxide, the keg  1  is disconnected from the dispensing system by removal of keg coupler  2 . A valve (not shown) on the keg prevents any egress of the contents during movanent thereof. The keg is then moved to the reclamation system, and attached to the keg coupler  2  that is connected to the inlet line that is coupled to the filter  16 , which releases the pressurized gas from the keg into the reclamation system. The gas is first passed through filter  16 . The filtration process removes any fluid contents from the gas, together with particulate matter. The gas is then passed into sterilizer  17  to remove any bacteria therefrom. After sterilization, separator  18  separates any nitrogen from the carbon dioxide and thereby assists in the recovery of the CO 2 . The nitrogen may be vented to atmosphere, or may be collected separately from the CO 2 . If the system does not include nitrogen gas, the separator  18  may be omitted. 
     The resultant CO 2  is then collected in collection tank  19  before being re-pressurized by the compressor  20  in order to be supplied to the gas ring main  9 . A collection rate of approximately 80% of reusable gas is obtainable by this process. A higher collection rate is not thought to be optimal because a large amount of particulate matter and bacteria remain in the final 20 of the gas left in the keg, which would require more sophisticated cleaning and filtration steps, and hence would be more expensive to operate. In addition, the remaining contents of the keg may have to be removed under a reduced pressure rather than at atmospheric pressure. However, collection of the final portion of CO 2  may be desirable in some circumstances. 
     It should be appreciated that, although a CO 2  bottle  10  is provided in this system as a back-up to the reclamation system, the amount of additional CO 2  that needs to be added to the drinks dispensing system is greatly reduced in comparison with prior art systems. The bottle  10  should therefore only need to be replaced infrequently. 
     Referring to  FIG. 4  a second embodiment of a gas reclamation system according to the present invention is illustrated which can be used to recover carbon dioxide and other gases and gas mixtures such as nitrogen and nitrogen/CO 2  from a keg. 
     The system comprises an input line attached to a keg coupler  2  for connection to gas filled keg. The keg coupler  2  will be of modified form as compared with a keg coupler used for dispensing beverage. In particular, the modified keg coupler  2  has a capped-off product port and a modified gas input port. In a conventional keg coupler used for dispensing beverage, the gas input port has a one way valve permitting gas flow only into the keg. In the modified keg coupler, the one way valve is reversed so as to allow gas flow only out of the keg. The modified gas port is used to recover gas from the keg so as to reduce the risk of product contamination from any beverage that may still be in the keg. If the conventional product port was used, this port connects to a lance that extends to the bottom of the keg so as to enable top pressure to force beverage out of the keg. That lance could readily be contaminated by residual beverage in the port and therefore it is advantageous to recover gas from a port open only into the top of the keg. The modified input port provides such a connection. 
     The coupler  2  is connected in series to a moisture remover  23 , an anti-vacuum valve  24 , a gas sensor  25 , a pressure sensor  26  mounted on a solenoid valve  27 , a sterilizer comprising an ionizer  28  and a de-ionizer  29 , and a compressor  20 . In this embodiment, there is no equivalent component to the collection tank  19   a  upstream of the compressor  20  in FIG.  3 . Four gas collection or storage tanks  19   a ,  19   b ,  19   c ,  19   d  are however connected downstream of the compressor  20  via collection lines  30  and respective valves  31   a ,  31   b ,  31   c  and  31   d , each of those valves incorporating a respective pressure sensor  32 . The collection tank  19   a  is connected by a valve  33  incorporating a pressure sensor  34  to the inlet to the compressor  20 , and the lines  30  are connected by a valve  35  incorporating a pressure sensor  36  to an outlet  37 . A central processing unit (CPU)  38  is connected to each valve, each pressure sensor, the compressor  20 , the anti-vacuum valve  24  and the gas sensor  25 . 
     On initial installation, the CPU  38  performs a series of pressure checks. This is carried out by opening valve  27  and operating compressor  20  with all the valves  31   a, b, c  and  d  open. The tanks  19   a, b, c , and  d  are thus pressurised to a preset pressure. The valves  31   a, b, c , and  d  are then closed and the gas pressure in each of the tanks is monitored by the pressure sensors  32 . This is to ensure that the tank pressures are maintained as will be the case if the tanks are not leaking, If the tanks are shown to be gas tight, the system is then ready for use. Before use however the tanks are emptied by opening valves  31   a, b, c  and  d  and opening valve  35  so that the tanks are vented to atmosphere. The system is now fill of air at atmospheric pressure. 
     Before a keg is connected to the coupler  2 , the system is evacuated to remove most of the air. The coupler  2  incorporates a valve (not shown) which is closed until the coupler is connected to a keg During the evacuation process, the valve  35  is opened, the compressor  20  is turned on, and the valves  33  and  27  are opened. After a predetermined period the valve  27  will be closed (at which point a partial vacuum has been established in the line between the coupler  2  and the valve  27 ). Thereafter the compressor continues to operate until a full vacuum is established in tank  19   a  and all the lines between the tank  19   a  via valve  33  to valve  27 . This reduces the amount of air in the system which could contaminate subsequently collected gas. The tanks  19   b ,  19   c  and  19   d  will however still be full of air at atmospheric pressure as will the lines  30  downstream of the compressor. 
     When a keg is delivered filled with pressurised gas, it is connected to the coupler  2 , such connection automatically opening the valve incorporated in the coupler  2  so that the line upstream of the valve  27  is in communication with the interior of the keg. Gas from the keg passes through the moisture  23  which drives the gas. The incoming gas pressure is monitored by the pressure sensor  26  associated with the valve  27 . The gas sensor  25  detects the identity of the incoming gas. If the incoming gas is carbon dioxide, that gas is to be delivered to the tank  19   a  (which is evacuated as a result of the earlier action of the compressor  20 ). Assuming that the detected gas is carbon dioxide, the valve  27  is opened, the valve  31   a  is opened, and the compressor  20  is turned on so as to deliver carbon dioxide from the coupler  2  into the tank  19   a . If on the other hand the gas detected by the sensor  25  is air, this gas should be delivered to the tank  19   b  and therefore the valve  31   b  is open rather than the valve  31   a . The delivered air will be mixed with the air already in the tank  19   b  but this does not result in any cross-contamination. Similarly, gas may be delivered to the tanks  19   c  and  19   d  by appropriate control of the valves  31   c  and  31   d . If some cross-contamination between the air originally in these tanks and the delivered gas is not a problem then the illustrated arrangement is sufficient. If however the delivered gas is for example nitrogen and cross-contamination with air is not acceptable, it would be necessary to provide an additional purge valve corresponding to the valve  33  connected by a T-junction to the pipe linking the tank to the associated valve  31   c  or  31   d  to enable evacuation of that tank before delivery of recovered gas. 
     As soon as the valve  27  is opened, the ionizer  28  and de-ionizer/filter  29  are turned on and compressor  20  is started. The processor  38  will then monitor the inlet pressure detected by a pressure sensor  26  and will also monitor the gas storage pressure of the tank to which the gas is being delivered via pressure sensor  32 . If the storage pressure exceeds a preset level the compressor  20  will stop and the valve  31   a, b, c  or  4  will be closed. 
     After the gas pressure within the keg connected to the coupler  2  as sensed by the pressure sensor  26  indicates that the keg has been evacuated the valve  27  will be closed. The coupler to is then disconnected from the keg, thereby closing the automatic valve embodied within the coupler  2  and the process can be repeated, that is the valve  35  will be opened, the compressor  20  will be started, and the system will be evacuated until a predetermined low pressure is established upstream of the valve  27 , whereupon that valve is closed. Further evacuation continues until the system is fully evacuated. The process can be repeated thereafter by connecting a new keg to the coupler  2 . 
     The CPU  38  performs various additional functions. For example, once a keg has been connected to the coupler  2  the processor  38  will check to see that the pressure within the keg is within preset limits. In addition, the processor  38  will monitor the pressure within the appropriate tank  19   a  to  d  to see if there is enough space in that tank to receive the keg contents. If either the keg pressure is inadequate or the tank pressure is too high the processor  38  will abort the cycle and indicate to the user that the selected storage tank is full. If on the other hand the tank does provide enough space to receive the keg contents, the processor  38  may vent a small amount of its contents into the system by opening the associated valve  31   a  to  31   d  to flush gas out of the pipes  30  via the valve  35 . This again reduces the risk of cross-contamination. 
     The ionizer  28  uses a high voltage negative ion to purify any contaminations found within the gas stream. The ionizer  28  is turned on once the processor  38  has indicated initiation of a valid gas recovery cycle. Incoming gas passed by the valve  27  will be totally ionized, thereby killing any bacterial or other contaminations found with it. After purification, de-ionization and filtering, the gas is drawn by the compressor  20  into the appropriate tank. Filtering will remove any biomass or airborne matter before the gas reaches the storage tank. 
     After completion of a recovery cycle, the processor  38  will indicate to the user that the cycle has been completed. Once the processor  38  has checked that the inlet system has been cleared, that is the keg coupler  2  has been disconnected and the line upstream of the valve  27  is at normal atmospheric pressure, the system will automatically start the process described above to clear gas from the system in anticipation of the next gas reclamation cycle. 
     The anti-vacuum valve  24  may be operated in the event that the compressor  20  stalls on start-up. Fault diagnostics may also be provided to ensure that the compressor  20  is functional by monitoring the pressure rise on starting. If no rise is detected when the compressor  20  starts, then a fault situation will be displayed on a control panel. 
     The gas sensor  25  may be set up to detect the presence of three gas types, for example carbon dioxide, nitrogen and oxygen A standard sensor can be used which relies on the principle of infra-red absorption. This process can accurately determine the identity of a gas present in a sampling chamber which is part of the sensor. The sensor can be calibrated using pure sample gas as references, the processor  38  thereafter storing this reference data for use in identifying the presence of particular gases within the system. Such IR absorption sensors are very low maintenance and do not require permanent stored sample gas to maintain their accuracy. 
     In the arrangement shown in  FIG. 4 , no connections have been shown for delivering pressurised gas from the tanks  19   a  to  19   d . Any convenient arrangements may be provided for such gas delivery. For example, in the case of tank  19   a , a simple T-junction (not shown) on the inlet to the tank  19   a  may be connected through a one way valve system to a beverage dispensing line such as the line  9  shown in FIG.  3 . Gas would therefore be delivered from tank  19   a  as necessary providing the pressure within the tank  19   a  was sufficiently high.