Safe Ammonia System Design in Large Applications
Against the backdrop of the ongoing climate change debate, Alexander Cohr Pachai, Technology Manager, Sabroe Factory in Johnson Controls Denmark, focused his presentation on the potential of ammonia refrigeration to help achieve climate targets.
He underlined that:
- NH3 is efficient and safe in practical use
- Strong track records exist in many industries
- NH3 s cheap and has no GWP
- Well educated workforce is found on all levels
- All components are available in the market
- Industry has more than 100 years experience with NH3
- Full product range of components and units NH3 exists
Mr Cohr Pachai also referred to a report by Global Industry Analytics predicting the global ammonia market would reach 174 million metric tons by 2015, including fertilizers and industrial applications.
With regards to the safe design of ammonia systems, he gave some clear and simple advice:
- Components have to comply with code of good practice and standards
- Valves need to be placed in way that allows for proper servicing
- Installation should avoid un-necessary stress on any part of the system
- Bridges over pipes should enable crossing to avoid stress on pipes, cladding and insulation
- When pipes pass through walls and sealing, the humidity membrane must be healthy
- A good maintenance programme is key
Cohr Pachai concluded: “From experience visiting sites in the US it is found that with good code of practice ammonia is a viable solution in large industrial refrigeration systems provided code of good practice. Training is required to have a good efficiency and a well-maintained and safe plant regardless the refrigerant. It is sometimes a bit underestimated what impact damaged insulation has on the total performance especially on low temperature systems.”
Industrial Ammonia Heat Pumps in Food Processing
Sam Gladis, Business Director – Heat Pumps at Emerson Climate Technologies, Vilter Manufacturing LLC, presented a case study of Kraft Foods installing an ammonia heat pump in their Oscar Mayer Plant in Davenport, Iowa, US.
Food processing necessitates considerable refrigeration and hot water loads. Ammonia is the refrigerant of predilection thanks to its “exceptional refrigerant characteristics paired with low cost,” said Mr Gladis.
The objective of Kraft Foods was to find a sustainable alternative to the use of fossil fuels as a means to heat water for sanitation as well as to realise energy savings. The installation of the industrial ammonia heat pump enabled the use of waste heat from the ammonia refrigeration system, to reduce heating energy costs by 61% and on site energy consumption for heating by 79%. In numbers, this translates into $268,875 in annual energy savings and a return on investment of 35%. Further benefits are a reduction in water consumption of 15 million gallons per year, by avoiding water evaporation or blow down from the evaporative condenser, in addition to operational and maintenance savings. The COP of the system in summertime is 6.5.
Previously the limitation for ammonia heat pumps was the lack of suitable high-pressure compressors (40 bar max). However, Vilter manufacturing has introduced single screw compressors that are suitable for high-pressure ammonia heat pump applications thanks to balanced internal forces.
As the energy saving utilization of ammonia’s heat of rejection was enabled via a retrofit to an existing system, design and build contractors, engineers and end users can all benefit from the application of this innovative technology in both new and existing systems.