To beer or not to beer- that is the question

Two miles of beer in an underground pipeline #Shakesbeer

To beer or not to beer

Historically, the idea of a beer pipeline has been confined to university dorm rooms in the early hours of the morning, a nonsense solution for a lack of booze that’s hardly a problem on most university campuses.

Enter Xavier Vannestenot an enterprising student, but the director and heir to De Halve Maan – Bruges’ only, continuously working, old brewery.

Being a brewery in the city centre space is quite a premium, so the bottling plant had to be moved out of the city, which means millions of gallons of beer a year has to be moved by porter into trucks and transported onto the next stage of the journey.

This is a mild problem in a small 11th century Flemish town with its impossibly quaint, cobblestoned, and tiny streets, it is home to some of the worst traffic in Europe and putting increasing pressure upon the council.

If you can supply an entire city with fibre broadband and waste water amenities, what’s one pipe to get hundreds if not thousands of lorries off the street?

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Xavier took the idea to the local council to get approval and the request did not fall on flat ears and was approved, and so work began on the pipeline, transforming the streets of Bruges into a work zone and drawing large crowds in the process.

The pipeline spans a short hop of 3.2km from the brewery to the bottling plant and can transport 1,060 gallons of beer an hour (or as known in the UK as the amount of rain falling on Glastonbury weekend) to be processed and shipped off to customers.

It is buried mostly around 10 foot deep (however dipping under the concert hall it will reach 150 ft deep) and made of extra stout food
grade polyethylene pipeline to appease the healthcare authorities and to deter the beer loving locals from having their own private tap.
The idea was floating around the office as to how this marvel was accomplished, so why not analyse the concept in Simcenter FlomasterTM software as it has a strong pedigree in modelling pipeline systems?

Using the reports of 1,060 gallons of beer per hour, the 2,000L storage tank will take roughly 30 mins to drain from the brewer, there is no need for pumps, instead it is only being driven by the pressure head from the storage tank and a handy elevation drop.

Using a flow regulation valve, made from a PID, a near constant flow rate through the pipe was achieved regardless of the level of fluid in the tank, leading to a smooth profile, as shown in figure 2.

As soon as the tank at the receiving end is full then the valve is closed, this causes a pressure wave through the beer which causes shockwaves and column separation within the fluid. In figure 3, shown in red is the pressure wave and in blue the volume of the cavity formed.

We can see, as the pressure in the pipe drops below the vapour pressure, cavities form and then collapse as the pressure increases again.

This is the main cause of such large pressure spikes in the fluid within the pipe. With these spikes in pressure comes hydrodynamic forces transferred to the polyethylene pipe which will cause stresses and strains that would have to be calculated by hand in other programs. However, in Simcenter Flomaster the hydrodynamic force is calculated within the simulation, which can then be exported to FEA programs through a native import.

The lowest grade polyethylene pipe of nominal bore of 75mm can withstand a total pressure of 5.0MPa. So at under 4 bar there is little chance of losing any of the amber nectar due to closing the valves too quickly.

Although I feel this kind of column separation needs investigating to see if there is a negative effect on the taste, a job I’d be far too eager to volunteer for, but they simply haven’t got back to me.

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Engineering simulation for the development of fluid systems.

FloMASTER is a powerful one-dimensional fluid-dynamic simulation tool for complex thermal-hydraulic systems.
FloMASTER is made by Mentor (now part of Siemens Industry) and distributed by BSim Engineering.

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