Beer dispenser

Details Beer dispenser Beer dispenser

2001-09-26

2004-12-07

Derakshani, Philippe (Department: 3754)

Dispensing

Plural sources, compartment, containers and/or spaced jacket

Cabinet-type dispenser for single mixed drinks

C222S547000

Reexamination Certificate

active

06827238

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for dispensing beverages, for example, beer, and in particular, but not exclusively, to a beer tap for dispensing draught beer.
When dispensing beer in a bar or other point-of-sale location, the beer is commonly stored in a keg at a remote location from the point of dispense. A gas cylinder which contains carbon dioxide, or a mixture of nitrogen and carbon dioxide is connected with the keg and serves to keep the dissolved gasses in solution and can drive beer from the keg to the dispense tap.
In order to ensure that the beer is in the correct condition as it is supplied to the tap, it is common to pass it through a cooler and a pressure restrictor before it is delivered to the tap. In some installations, a pump is provided between the keg and the tap.
In conventional beer dispense systems, the tap is a simple on-off tap which is spring biased into its on and off positions. Prior to use, the dispense system is set up with the intention that the beer is dispensed at the correct rate and in the correct condition when the tap is fully open. Conventional taps have a simple plug valve member which is moved into and out of engagement with a valve seat through which the beer flows. Downstream of the valve is a nozzle normally of uniform internal bore to bring the flow into a continuous stream. The intrinsic design of these valves does not readily allow controlled break out of gas from beer and, hence the extent of beer head formation may be variable.
A generic tap of the type described above which is used by pubs and bars for dispensing draught beer is (schematically illustrated in the schematic representation) shown in
FIGS. 1 and 2
. The tap comprises an inlet pipe
1
which opens into a cylindrical chamber
2
. A valve head
3
is centrally located in the chamber and is arranged to close against a valve seat
4
which is formed on the upper end of a depending dispensing spout
5
. The diameter of the valve head
3
is significantly less than the internal diameter of the chamber
2
so that beer may flow around all sides of the valve head to reach the dispensing spout
5
. Thus, in use the beer flows into the tap through the inlet pipe, flows against the valve head
3
and then down through the dispensing spout. As can be seen from
FIGS. 1 and 2
, on impacting the valve head, some beer will flow in either direction around the head.
The inventors have recognized that this flow pattern gives rise to turbulence and stagnation points within the chamber
2
, particularly in the region opposite the inlet pipe. This causes flow energy to be used up and thus a relatively large pressure drop is produced across the tap.
Thus, the beer in the kegs must be provided at a sufficiently high pressure to allow for this pressure drop.
In addition, the flow through the taps may have a detrimental effect on the quality of the beer being dispensed because the transition of the beer from an unsaturated to a supersaturated state may occur within the tap itself.
It is often important that beer be dispensed with an attractive head of foam. The head on draught beer is known to be produced from the breakout or separation of gas in the beer to produce bubbles and a “tight” creamy head formed of small bubbles is usually considered most desirable.
Beers currently marketed are generally of one of two types; ales typically containing 1.1-1.7% vol/vol of dissolved carbon dioxide and often 15-55 mg.l
−1
of dissolved nitrogen, or lagers containing 2.0-2.8% vol/vol of dissolved carbon dioxide. In either case, the beer enters the glass as a supersaturated solution which means that the dissolved gas it contains has the potential to break out of solution. The extent to which this occurs depends on a number of factors. These include the level of supersaturation, the flow conditions and the existence of nucleation sites to initiate bubble growth. During beer dispense, the generation of gas bubbles in solution originates predominantly by heterogeneous bubble nucleation. This means that bubbles are either nucleated at a surface containing pre-existing nucleation sites or in solution as a consequence of air being entrained in the beer as it flows into the glass.
2. Discussion of the Related Art
Many different methods have been tried in the past to produce a high quality head on draught beer. For example, nitrogen may be added to the beer and also a flow restrictor is usually provided in the base of the dispensing tap.
Such flow restrictors traditionally are flat discs containing five holes each having a diameter of from 0.5 to 1 mm. The decreased flow aperture provided by the holes causes a pressure drop across the flow restrictor producing gas breakout and the formation of a head on the beer.
However, the problem with these known taps having flow restrictors is that a high pressure drop occurs across the flow restrictor itself which can lead to a loss of control of head formation.
OBJECTS AND SUMMARY OF THE INVENTION
Viewed from a first aspect, the present invention provides a beverage dispensing apparatus, the apparatus being formed so as in use to provide a vortexial motion in the mass of beverage flowing through the apparatus.
The vortexial motion of the invention in the mass (i.e. the bulk) of the beverage is to be distinguished from the existence of localised vortices or eddies which occur in the turbulent-flow in disperse taps. However, it should be understood that the flow within the vortex will itself typically be turbulent.
In the vortexial flow of the invention, a low pressure area is produced at the center of the vortex so that the pressure in that region falls below equilibrium pressure and thus results in gas separating out from the liquid beverage. Since the gas breakout is achieved without the need for a flow restrictor, the pressure drop associated with these devices does not occur. Consequently the beverage may enter the apparatus at a lower pressure. Moreover it has been found that a high quality head is formed on the draught beverage dispensed from the apparatus of the invention.
It has been found particularly effective to provide the apparatus with a flow chamber having a substantially circular cross section in which the vortexial motion is induced together with an inlet leading to that chamber and an outlet leading therefrom.
A particularly effective way to induce the vortexial motion in such a chamber is for the inlet to extend substantially at a tangent to the circular cross section of the flow chamber. In this way, beverage flowing into the apparatus flows into the chamber from the inlet and along the inner face of its side wall. Thus the beverage flows around the chamber and thereby sets up a vortexial flow.
While it is possible to vary the direction of the flow of beverage relative to the flow chamber, preferably the beverage inlet comprises a conduit which extends substantially perpendicular to the longitudinal axis of the flow chamber so that the flow path of the beverage forms a tangent to the flow chamber, as previously discussed. Preferably the inlet conduct is also substantially horizontal.
Although the action of the beverage flowing around the walls of the flow chamber is sufficient to cause a vortex motion, it is significantly essential to have a vortex finder within the flow chamber aligned in relation to the beverage inlet such that, in use, beverage flowing into the flow chamber is guided in a circular path between the outer surface of the vortex finder and the inner wall of the flow chamber. Thus, with a vortex finder provided as described above, the beer flowing through the apparatus is encouraged to flow cyclically around the flow chamber.
The vortex finder could be of any form which provides the required flow pattern. Preferably however, the vortex finder comprises a portion in the form of a cylinder.
Still more preferably, the vortex finder further comprises a conic or frusto-conic part provided at the downstream end thereof (i.e. the end closer to the outlet). This further e

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