Six-second pints of stout, electronic beer-saving and 140 metres of a draw from keg to tap… John Smee looks behind the scenes at the state-of-the-art beer dispensing system in the revamped Páirc Uí Chaoimh
Mech

Frank Maher is technical services manager for Heineken Ireland and was assigned the role of site project manager for the Páirc Uí Chaoimh redevelopment project. Heineken Ireland was awarded the contract for pouring rights in the redeveloped stadium and Maher’s role was to implement Heineken’s plan for designing, installing and operating the dispense system which would be used to sell their products (Orchard Thieves cider, Murphy’s stout and, of course, Heineken lager) to tens of thousands of concert goers or GAA fans.

The south stand of the stadium is where most of the bars are located – there are kiosks across three floors (Fig 1). The premium level has three conventional bars with their own dedicated keg store, but the majority of the stand is serviced by one large, centralised keg store and a series of kiosk bars on every level above.

CLICK TO ENLARGE Fig 1: Kiosk bar in Pairc ui Chaoimh’s south stand

It is from these bars that the vast majority of beer is sold and so a great deal of consideration was given to their design and specification to ensure that despite the high volumes, the product quality and ‘customer experience’ was to a very high standard.

The kiosk bars are equipped with electronic beer dispense taps manufactured by Qualflow Systems and these can dispense a pint of beer in just six seconds (including stout – in a single pour!). There are ten taps in each bar, meaning that each bar has a theoretical capacity of one hundred pints per minute.

Of course, the reality is that it would not be possible to process this volume of customers in such a short space of time. However, this rate of pint pouring is very much deliberate on the part of Heineken.

“The beer pouring is never going to be the bottleneck when it comes to selling drinks at the bar,” explained Maher. “With this system, you’ll always be able to pour beer faster than the people at the till can sell it, and that’s intentional. We strongly discourage pre-pouring of beer at these bars.

“This system gives the confidence to the bar staff that they have as much capacity as they need, on demand, so that they can pour beer to order. They don’t have to rely on old technology, which would mean pouring twenty or thirty pints in advance and hoping that they are sold. That was a really big part of it for us at Heineken.”

Improving the customer experience with technology


CLICK TO ENLARGE Fig 2: A kiosk bar on Páirc Uí Chaoimh’s south stand with electronic taps

Another major element was the ‘recalibration’ of the bar staff who might be inclined to pour extra beer when it is quiet in anticipation of a rush. Maher addressed this with some of the younger staff on a match day, when the bar first opened.

“I said to them: ‘In six months’ time, you’ll be on the other side of the bar – buying yourself a pint at the Ed Sheeran gig! If you come up to the counter and order a Heineken, and there’s twenty pints sitting there getting warm and there’s no head on any of them, how would you feel about it? Wouldn’t you prefer if it was freshly poured to order?’

“We’re constantly trying to improve the customer experience to make sure that the beer is freshly poured, cold and hasn’t been sitting there. I can tell you, it works. On our opening day, we were pouring six-second pints at 1°C continuously. That’s in the top kiosk – 140m away from the keg cold room with a 30m vertical lift.”

Achieving this dispense temperature despite such a long draw from the keg storage room to the tap is mainly due to the fact that the bar designers broke with tradition and located each draught beer cooler in the bar itself – as opposed to down in the keg store, where it would typically be located in a pub.

The reason for this is simply because it gets the cooling process closer to the point of dispense, for the lowest possible serving temperature. In a normal pub, this is typically never more than about twenty or thirty metres and the cooler is almost always located in the cellar for convenience. But in the south stand in Páirc Uí Chaoimh, the draw exceeds 140m for some bars, so getting the draught beer-cooler close to the taps makes a very significant difference.

CLICK TO ENLARGE Fig 3: Behind the scenes: draught beer cooler (foreground) adjacent to electronic taps (background). In a regular pub, this cooler would be located in the cellar, but having it closer to the point of dispense is best to achieve the lowest serving temperatures

A draught beer cooler is an insulated tank of water at 1°C. Stainless-steel coils are submerged in this tank. Beer enters the tank at 8°C, flows through the product coils and leaves the tank at the correct serving temperature. Thus, heat exchange takes place and the beer is cooled.

The specific serving temperature is determined by the length of the product coil. Longer coils give a longer residence time in the ice water. Longer exposure to ice water means colder beer. Stout and ale are served warmer than lager and cider.

The temperature of the ice water tank is maintained though the presence of a wall of ice around the perimeter of the tank, which builds on a copper evaporator through which refrigerant is circulating. Beer cooling is achieved using latent heat, i.e. as the system is loaded, ice melts away but temperature of the coolant (i.e. the ice-water) does not change. This stability is key to beer temperature and quality/consistency.

Accommodating spikes in demand


CLICK TO ENLARGE Fig 4: Draught beer cooler cutaway view, with product coils shown on right

Another advantage of applying the principle of latent heat to cool the product is that the draught beer-cooling system can accommodate enormous spikes in demand over a very short period (such as half time at a sports match or the interval between acts at a music festival) without a loss of cooling performance. The cooler simply melts more ice when it is loaded and recovers when the bar gets quiet again.

Glycol-based cooling systems use sensible heat for cooling (they do not have an ice reserve) and thus do not have this advantage. They must be fitted with very powerful refrigeration units specified for the ‘worst case scenario’ demand at the bar, or they will struggle when it gets busy.

A glycol system in this application is therefore over-powered for the majority of its working life. This can lead to excessive power consumption and refrigeration unit short-cycling, which carries with it a whole host of other problems. Cooling using sensible heat is much more suited to applications with steady and predictable demands.

The coolers for Páirc Uí Chaoimh were built to-order by Kilkenny Cooling Systems to an ‘event specification’, with a larger ice reserve than standard to handle longer demand peaks. The pumps were also upgraded to provide sufficient coolant flow in the 140m insulated python run back to the keg store.

The keg store is located on the ground floor of the stadium and is the heart of the beer-dispense system. Typically, installers aim to store kegs relatively close to the point of dispense (i.e. the bar). However, this plan was quickly dismissed for the Páirc Uí Chaoimh project, as it would mean bringing hundreds of full kegs up through the lift systems to the bars throughout the stand, and then bringing all the empties back down again after the event. This is impractical.

Instead, a plan for a centralised keg store in the south stand was devised. This large insulated room is capable of storing up to four hundred kegs and maintaining them at 8°C. Kegs are delivered in the days preceding an event, to allow time to be brought down to temperature.

During events, staff work in the keg room continuously, changing kegs when required and removing the empties to a storage area outside. A full keg might only last ten minutes during busy periods, so kegs are being changed constantly.

Maintaining correct keg pressure


CLICK TO ENLARGE Fig 5: The main tunnel under the south stand with the door to the keg storage area on the left. The insulated beer line python can be seen fixed to the ceiling. The beer is distributed through this python throughout the stand to all kiosk bars. The coolers in the bars pump icewater back through this python to chill the beer as it is pumped from the keg store to the bar

Nominal keg pressure is 38PSI (2.62 Bar). Beer is propelled from the keg using a mix of CO2 and nitrogen through the lines for serving. For a normal pub, this pressure would be sufficient to achieve pouring beer at the tap. However, given the length of the python runs and the elevation of the bars in Páirc Uí Chaoimh, standard pouring pressure is not sufficient. Increasing the gas pressure is not an option either, because a higher pressure would affect the CO2 absorption of the product affecting the quality.

So, if the propellant gas pressure cannot be increased, how is it possible to overcome the 30m elevation to the bars from the central keg store? The solution is a series of diaphragm pumps which drive the beer up to the taps. Each tap requires one beer pump – or two pumps in series for the highest bars (tandem pump).

The diaphragm pumps are powered by air compressors, with each compressor driving five pumps. The compressors are each connected to a ring main, with one ring main per kiosk. It is the ring main pressure that determines the flow rate of the product at the taps.

The pressure is carefully calibrated to achieve six-second pouring of pints at each bar. The beer pump is set to maintain the calibrated pressure in the beer line. When the tap opens above in the kiosk, the pressure in the line drops and the beer pump engages.

When the tap closes, the pressure reaches its set point and the pump disengages. This is a system which is a lot more common in the UK, where the propellant gas mix does not contain nitrogen and thus must operate at lower pressures, limiting its application potential.

The beer flows through an electronic fob, which contains a float-switch that communicates the with fast-pour tap in the kiosk above. When the keg is empty, the float drops. This deactivates the tap above meaning that it cannot be opened for pouring – as to do so would fill the line with foam/gas. Thus, the line remains primed with product at all times.

Minimising beer waste


CLICK TO ENLARGE Fig 6: Central keg store (almost empty!) with board containing beer pumps and fobs

A significant challenge to be overcome with the central keg-room plan was the potential for beer waste resulting from the long python run from the keg store to some of the furthermost bars. A python is an insulated bundle of ten half-inch product lines and four coolant recirculation lines.

It was calculated that each of the product lines contains up to 14 pints of beer or cider in some of the most distant bars. Multiply this by ten product lines means well over a keg of beer waste per bar at the end of an event or when the lines are being cleaned. This is not acceptable.

The solution to this is twofold. It is achieved through a clever system that tap manufacturers Qualflow call ‘beersave mode’, combined with careful staff training and what Heineken’s Frank Maher calls a ‘controlled shutdown’. The beersave function on the tap bypasses the signal from the electronic fob, which under normal operation shuts down the tap operation in anticipation of a fresh keg – keeping the whole system primed with product. With beersave, the tap stays running until the line is clear of beer. Maher describes how it works:

CLICK TO ENLARGE Fig 7: Tandem beer pump (top) and fob (bottom)

“As part of the commissioning, we identified how much beer was in each line. For example, on the top floor we know that there’s 14 pints in each line,” said Maher. “When a keg is empty, the two choices are: couple up another keg and keep serving, or they could decide not to couple up another keg.

“If that’s the decision that’s made up at the bar, the keg-room staff connect the keg coupler to a beersave socket instead of connecting it to the fresh keg. This connects the propellant gas directly to the beer line – bypassing the keg – allowing the gas to directly propel the beer to the tap. The gas chases the beer all the way up along to the tap, and the bar staff keep pouring until the tap stops. They’ve now emptied the line. They do this with each of the taps in turn as the gig comes to a finish.

“Staff training is a big aspect of this, because you wouldn’t have this procedure in a regular bar. There’s a learning curve that they’re going through now where people are making key decisions at different stages during an event. We’re looking at what we call a ‘controlled shutdown’.”

Equally, at the beginning of the event, there is a controlled start up. The staff may not want to prime all of the taps. They can prime your taps as quickly as they want, of course (depending on the crowd), but the caterer needs to make the call.

CLICK TO ENLARGE Fig 8: Pythons (left) run from the keg room to bars throughout the south stand. A bank of compressors (right) power the diaphragm pumps. There are two beer pumps for each python

“Even well before the end of the event, the caterer might make the call to start shutting down taps,” Maher continued. “So as you get to the end of any gig, instead of having ten taps pouring in the bar, you might be down to just one or two. They’ve made the decision based on looking at the crowd – they don’t want beer sitting in all the lines which may be run to waste, so they blow them through one by one. The goal is to be down to just one tap operating in the kiosk at the end of the event.”

Páirc Uí Chaoimh had its grand opening in early July, with back-to-back football and hurling games, and the beer-dispense system performed admirably with sub-2°C serving temperatures throughout the stadium. But the real test of the dispense system will be concerts, where there are a lot more people and fewer families, and that means more demand for beer. Ed Sheeran hits the Cork stage in May 2018, so it will be the best part of a year before there is a real opportunity for the beer-dispense system to prove it can operate as designed.

http://www.engineersjournal.ie/wp-content/uploads/2017/10/Pairc-Ui-Chaoimh-1024x580.jpghttp://www.engineersjournal.ie/wp-content/uploads/2017/10/Pairc-Ui-Chaoimh-300x300.jpgMary Anne CarriganMechCork,machinery,mechanical
Frank Maher is technical services manager for Heineken Ireland and was assigned the role of site project manager for the Páirc Uí Chaoimh redevelopment project. Heineken Ireland was awarded the contract for pouring rights in the redeveloped stadium and Maher’s role was to implement Heineken’s plan for designing, installing...