Dynamic Earth HAC Design

For us, the natural progression from Baby HAC was building a pre-commercial demonstrator hydraulic air compressor. We found a home for the technology, thanks to our friends at Science North‘s Dynamic Earth, which is also the home of Sudbury’s famous Big Nickel. DE HAC will be part of the exhibit at Dynamic Earth. A rendering of the facility – naked – is shown below. It is around 30m high from top to bottom, and the way it works is a bit like an inverted syphon. Water passes between 2 atmospheric tanks held aloft, inducting, compressing and drying air as it goes. Yes: the compressed air that comes out of a HAC, which uses water to compress the air, is drier than mechanically compressed air – it’s just one of the strange but true facts about Hydraulic Air Compressors!

dynamic-earth-model
A 3D Solidworks rendering of the Dynamic Earth HAC Demonstrator prepared by our project engineers, Black Rock Engineering, of Lively, Sudbury. The blue ‘blob’ at the bottom is the compressed air – water separator.

The design of DE was based on the design of the HAC that Charles Havelock Taylor prepared for Peterborough Lift Lock. The Lift Lock itself is an amazing piece of engineering in its own right. But we think that the hidden secret in the mass concrete abutments of the lock (which, incidentally, we know to be the first mass concrete structure to be built in Canada) is even more amazing. Our friends in the Federal Ministry of Environment’s Parks Canada allowed us to pass a sewer camera through what is left of the jewel inside. This video will undoubtedly be of interest to purveyors of industrial heritage.

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The cover plate over the Hydraulic Air Compressor installed within Peterborough Lift Lock. This HAC is in plain view and has been trodden on by the thousands of people that visit the attraction every year. Check out the cast credentials: “The Taylor Hydraulic Air Compressing Company Limited, Montreal”. They did exactly what they said on the lid and we think this is a good model to follow.

The first air-water mixing head that we will use in the Dynamic Earth HAC, will be an exact clone of the one installed in Peterborough Lift Lock. That way, we know our head will definitely work; Taylor’s head operated in the lift lock from circa 1905 to 1967. The image below is a photo of a photo on an information board at the visitor centre at Peterborough Lift Lock, showing the air-water mixing head in a packaging frame, before installation. Somebody obviously knew they were creating engineering history with this device: they had the foresight to include a measuring scale on the left hand side of the frame to help engineers of future generations reverse engineer the head geometry!

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Taylor’s air-water mixing head at the Peterborough Lift Lock HAC

Alex has several interesting ideas of how to improve on Taylor’s head design, including adopting an ‘inside out’ in-pipe eductor system. What amazes us is that engineers 100 years ago were able to design workable systems without the benefit of the modern day computational fluid dynamics systems that we rely on. No wonder engineers back then have a reputation for being in love with their slide rules: they had to use them! We like to think that the modern tools allow us to exercise our creativity, but the truth is that frequently, after all the pretty pictures have been made, the HAC Pack’s optimisation efforts frequently converge back towards geometries that Taylor and his contemporaries established a century ago.

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