Why does we have so many ammonia refrigeration plants?
With dairy, meat and other agricultural products making up a significant proportion of our food chain, it’s no surprise that we have a large number of ammonia refrigeration plants operating around the world.
Why do we use Ammonia, why not something safer?
Refrigeration plants can use a variety of motive fluids, with the one of the most common materials for large scale plants being anhydrous ammonia. Ammonia is commonly used as a motive fluid for several reasons:
Ammonia is a non-ozone depleting material
Anhydrous ammonia is relatively cheap in comparison to other synthetic refrigerants.
Although it can be ignited, anhydrous ammonia is far less flammable than alternatives such as propane
Ammonias properties make it a very efficient refrigerant for use in the meat and dairy processing industries
All of these points make ammonia a great option for use in large scale refrigeration plants, however unfortunately, ammonia also has a few properties that make its use rather hazardous:
Ammonia is acutely toxic – inhaling anhydrous ammonia can lead to serious injury or death
Anhydrous ammonia can behave as a dense gas – this makes it tend to travel as a concentrated cloud along the ground instead of dispersing up into the air. A significant leak of ammonia can form a very toxic gas cloud that can stick around for a long time
What are we doing wrong?
With the sheer number and scale of ammonia refrigeration plants being operated across the world, one might expect that operators would have a good understanding and appreciation for the hazards involved with anhydrous ammonia. However, evidence from severalincidents, some very recent, have shown that there are still some serious shortfalls in how some facilities are being operated.
There are several factors that appear to have contributed to the frequency of incidents at ammonia refrigeration facilities. Here are some of the more prevalent ones.
Operators lack process safety knowledge
An ongoing theme I have observed while working with companies operating ammonia refrigeration facilities has been the lack of in-house expertise when it comes to the hazards of working with anhydrous ammonia. Many operators will outsource their ammonia operations to external contractors while making the assumption that they will handle the process safety requirements of their site, however this not sufficient to effectively manage process safety at their facility.
Operating companies need to have goodprocess safety knowledgefor their business across the board, this is not just a recommendation but a legal requirement in many countries.
Many refrigeration plants operating in Australia and NZ are several decades old. Over time, these facilities have been upgraded and expanded to keep up with our growing industry. It’s not uncommon to find several separate ammonia refrigeration loops at one site, or systems that have clearly had significant changes tacked-on over the years to the point the site resembles something like the Frankenstein monster. Having several semi-separate systems increases a facilities complexity and therefore significantly increases the risk for something to go wrong.
Refrigeration doesn’t get the attention it deserves
With refrigeration being a utility process for the meat and dairy industry, it is rare to find an operator where refrigeration is their primary business. All to often this part of the process comes second to production and food safety, and the required attention for working with such a hazardous substance is not always as good as it ought to be.
It’s not all bad news, things are getting better
It’s worth noting the significant efforts many businesses have been making to improve process safety within their facilities.
Several companies operating ammonia refrigeration facilities have taken significant strides in improving process safety at their plants. Businesses have taken up in-house expertise on process safety, engaged with consultants, and invested significant time and money into identifying the hazards at their facilities and improving safeguards to manage their risk.
What do we need to do?
Below are a few points that an operator of a refrigeration facility must understand before they can effectively manage the risk at their site:
What can go wrong – what are the hazards and how are they caused
What are the control measures that protect against the hazards, how suitable are they for the specific hazard
How likely is the risk and how severe is the harm that might result
Is there enough control measures and are they effective enough to manage the risk, can we do more to reduce risk at our site?