One of the leading low-charge ammonia systems suppliers Down Under, Scantec, has so far completed six installations of its Low Charge NH3
systems, mostly for cold store/food processing facilities, but is now looking into low-charge plate freezers and carcass chilling.
“We have just received firm orders for two more; we are currently signing a contract for a job in China and we have verbals for two (perhaps three) more in Australia,” says the company’s managing director, Stefan Jensen.
Like a few companies in the US, Scantec develops central low-charge NH3
plants, where the operating charge in the evaporators is so low that in a typical cold store with three evaporators, loss of charge in one coil will not increase the NH3
concentration in the freezer beyond ~200 ppm. It takes 5000 ppm to pose a significant safety risk to humans. The systems typically contain between 7.69-9.2kg per ton of refrigeration (TR).
systems can be applied in much smaller applications than conventional NH3
‘liquid overfeed’ systems, typically for most semi-industrial applications of 30-50 kW and above, according to Jensen, who asserts that low-charge NH3
can deliver 3-4 times as much cooling capacity per kilogramme of charge compared with liquid overfeed systems.
Other local players on the ammonia technology front (Australia and New Zealand) include Gordon Brothers Industries, Mayekawa Australia, Tritech, Oomiak and Cold Logic.
John Mott, general manager at Gordon Brothers, a Melbourne-based specialist in ammonia and hydrocarbon refrigeration technology, said the company has supplied around 15-20 of its low-charge NH3
‘Enviropack’ systems in Australia, and an additional three in New Zealand.
The units are designed especially for domestic and business air conditioning and contain level 3, secondary containment housing and a very low charge amounting to roughly 0.8 lbs or 0.36kg/TR, some 12 times less than the maximum US charge to be defined as 'low charge'.
Mott, who worked in the US ammonia refrigeration industry in the midwest before returning to Australia, pointed out the differences.
"They (the US) use 15 million tonnes of anhydrous ammonia liquid per annum. There are 45 ammonia storage depots located across the midwest with about 10,000 tonnes of liquid in each and they are all connected by 5000 km of ammonia liquid pipelines fed from tanker terminals in the Gulf of Mexico. In Australia we use about 100,000 Tonnes per year so only about 0.6% of that."Regulation in Australia still favouring traditional ammonia systems
Scantec is currently designing a larger central plant for a client with a capacity of 2.5MW, containing around 1700 kg of ammonia refrigeration or 5.38kg/TR.
In some countries like France, safety requirements become very difficult to comply with for charges of 1500 kg and upwards. Similarly in the US, the regulations are more stringent than in Australia but Jensen believes it is only a matter of time before this changes.
“When that happens, the market for low-charge NH3
systems in Australia will grow significantly simply because systems with large NH3
inventories will attract significant compliance costs. The new the ISO5149 already has a 4500kg ammonia charge limit, but it is not yet known what this triggers.”
Jensen estimates that there are currently around 100,000 refrigerated warehouses in Australia, the vast majority of which are using HFC systems and in need of conversion.
“Around 3,000-5,000 are candidates for low-charge NH3 and they all stand to save 40-70% on their power bills if they convert,” Jensen says. “These systems will all range in capital cost from $0.5 to $2 million and all conversions will need to be completed over the next two decades. This gives you an idea of market size just in that sector.”
It is true that low-charge ammonia systems are now becoming popular in the US, where, similar to Australia, there already existed a strong tradition of conventional ammonia refrigeration systems.
Companies like LA Cold Storage (NXTCOLD systems), Star Refrigeration (through its Azane subsidiary) and Evapco (Evapcold systems), who also distribute in Australia, are driving the market. The 10,000 lbs (4,500kg) NH3
inventory limit that triggers the US Occupational Safety and Health Administration’s Process safety management regulation is also forcing many end users to opt for systems with smaller charges in the US, Jensen says.
In some US states this has been reduced even lower to 5000 lbs (2,268kg) amounting to even greater compliance costs for end users. Below 100 lbs (45kg) charge, end users are left alone and this is why there is a big push to sell multiple smaller units each with under 100 lbs of ammonia charge. But this jeopardises energy performance and affordability, according to Jensen.
For example the NXTCOLD systems (single stage systems with electric defrost) contain 0.77-1.5kg/TR but in doing so sacrifice energy efficiency for reduced ammonia charge. Meanwhile, Evapco’s units contain around 1.13-1.36kg/TR.
Jensen has spoken with his US counterparts and believes installing multiple low-charge units in large warehouses is simply not cost effective. But he said he had spoken to a number of industry figures who believe low-charge NH3
to be the “only future” for ammonia in the US, and that the technology would continue to spread worldwide from there.
Gordon Brothers experimented with ‘ammonia dry’ low-charge systems during the 1990s but despite how “efficient, reliable and cost effective” they had proven to be, the technology did not take off at the time. The systems, originally developed by Mycom (Mayekawa) in Japan to try to cope with tight restrictions on ammonia use imposed by the Japanese government make Japan “world leaders” in the technology and its safe containment, according to Mott. “They even have Level 4 safety containment systems which are not available for export outside of Japan.”