Step by Step

Article by Stephen Drew FIChemE

Imma Gambardella/

Why classic pinch technology used in the NZ food industry is just as valid today as it’s ever been

IN 1969, I was about to embark on my chemical engineering education at the UK’s University of Leeds. It was a big year for music, with many classic songs foretelling the future ahead of us. But did we listen to those famous George Harrison lyrics in “Here Comes the Sun” and John Fogerty’s omen telling us about a “Bad Moon Rising”? Fifty years on, “Sun, Sun, Sun here it comes” and “Looks like we are in for nasty weather” could easily sum up where we are today all around the world.

Twenty years on, in 1989, I was working in the food sector in New Zealand and trying for the first time to understand how process heating and cooling could be better integrated on our large dairy and meat processing sites. I still remember IChemE’s contribution with its publication about process integration, which changed my world and got me involved with those pioneering days of pinch technology with Linnhoff March.

We did indeed show that step-change reductions in both hot (coal and gas in boilers) and cold utilities (grid renewable electricity in New Zealand) could be made. Many of these sites are still producing dairy and meat products today with the same steam boilers running now at times at low fuel efficiencies, with huge standing losses and of course with high carbon emissions. This is one of many contributing reasons as to why New Zealand’s energy productivity and greenhouse gas profile hasn’t gone down.

But we could have had more fossil boilers built if it wasn’t for the start of electrification and what we called electro-technologies in the electricity industry. We had an alliance called UIE to promote knowledge about industrial electro-technologies. Sadly, this international collaboration in RD&D all came to an end in 1996 as electricity companies became privatised. Pioneering work was done with many of the technologies that have become common place in modern dairy plants in New Zealand, like mechanical vapour recompression (MVR) milk evaporators, our biggest untold energy efficiency success story for industrial heat pumping.

Some of this past electricity industry RD&D work paved the way for new materials for thermal storage like iron oxide sintered into blocks which can be heated up to 1,000°C. Feolite is one of those storage materials developed by the UK electricity industry in the 1960s to keep coal-fired power stations working efficiently at nights. I like telling people that the Feolite material in my home daytime-charged (from solar) storage heaters came from nationally-funded RD&D completed 50 years ago.

Article by Stephen Drew FIChemE

Consultant, SRD Consulting

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