DEMM Engineering & Manufacturing
Energy efficiency
Ashburton Meat Processors is not only saving more than $250,000 a year, it’s also done away with light fuel oil, which has halved its CO2 emissions thanks to heat pump technology.
Recovered heat from refrigeration means Ashburton Meat Processors is getting more hot water than it needs, production is more reliable and there’s ample room for future growth.
The firm, owned by Verkerks, processes around 250,000 animals a year, equating to 10,000 tonnes of meat products.
Already operating at the limits of what the plant could handle, the site needed to expand in mid-2012, due to winning a major contract with Porkcorp NZ.
The expansion was a perfect opportunity to re-think production and ‘future proof’ the plant.
Several small refrigeration units were to be replaced with an efficient centralised system – it was ideal timing to revisit the plant’s water heating. With a focus on environmental performance, the firm opted for a new generation high-temperature heat pump, thought to be the first installation in New Zealand.
The heat pump uses ‘free energy’ from refrigeration condensers to generate 70°C hot water – much hotter than is achievable with standard heat recovery systems on refrigeration.
With the addition of a small LPG burner, the heat pump has replaced the light fuel oil boiler, cutting CO2 emissions by 1,160 tonnes a year. All told, the project has cut energy use by 27 per cent, worth $235,000 a year.
Previously, the refrigeration units across the site were inefficient and expensive to maintain. The new, centralised ammonia-glycol system has reduced energy use by 424 MWh a year, saving $ 63,800. It’s also eliminated the need to use costly (and soon to be banned) Freon.
With ageing pipes and constant vibration, Freon leaks had been common, and weren’t always detected until plant failed – and finding the source could be tricky. The new system has less pipe work, , fewer valves, better monitoring and better control than the units it replaced.
It’s not only less prone to leaks, it’s easier to spot them thanks to the glycol used. The company estimates its maintenance savings at $20,000 per year.
Although there’s a perception that ammonia is less safe than Freon, the ammonia is only within a closed-loop system in the control room, with glycol running out to the plant.
The meat-processing firm is typical of most industrialscale refrigeration systems. With a large amount of refrigeration, comes a large amount of heat to dump – which is usually done via a cooling tower or evaporative condenser.
Standard heat recovery systems can recover 35-45°C water for use in the plant, but that’s not terribly useful as most processes need water at much hotter temperatures.
By contrast, the high temperature heat pump uses ‘free energy’ from the condensing section of the refrigeration system, as the evaporating section of the heat pump. This recovers all the heat and uses it to generate 70°C hot water – far more useful, as it needs only a small energy boost to reach the necessary 90°C.
Energy savings from the heat pump are calculated at 1,544 MWh a year, worth $171,200.
Hot water generation from a heat pump has always been technically feasible, but this is the first application of its kind in New Zealand that we’re aware of.
The firm is now installing tanks to store hot water overnight, and maximise its energy savings. This should save a further $ 60,000 in energy a year – on top of the $235,000 already saved.
Dave Graham, operations manager at the firm says: “This project solved all our capacity issues. Before we were running at the limit of our refrigeration plant and we were struggling to get enough hot water. Now we have an abundance of both chilling and hot water. We even have room for future expansion.
“The high temperature heat pump is a potential game changer for New Zealand Inc. Hot water generation from a heat pump has always been technically feasible, but this is the first application of its kind in New Zealand that we’re aware of.
“If we’re serious about moving away from coal and other fossil fuels, then this is the technology that we need. It’s reliable and proven. You can have confidence that it will work well and make significant cost savings.”