A great deal of energy is required to process 5,000 tonnes of slaughterhouse by-products and food residues every week. Maple Leaf’s Rothsay plant located in Dundas, Ontario, accomplishes this feat very efficiently. The plant consumes about 43 m3 of natural gas/tonne of product, compared to 60 m3/tonne consumed at other plants. The plant's annual energy bill is about $7 million, of which $4.5 million is spent for the purchase of natural gas.
Despite doing well energy-wise, the Rothsay team nevertheless decided to perform a global analysis of its plant through process integration, in a bid to identify new energy-saving opportunities. Process integration goes well beyond traditional energy audits by taking a systematic look at all the ways in which energy is used throughout a facility and how its various systems interact with one another, allowing to determine the true energy balance and the most important aspects to improve in order to save energy.
Several Million $ in Savings
The process integration study conducted at the Rothsay plant identified a set of measures representing $1.1 million in savings, with a payback period of less than 2 years. Projects totaling about 30% of these savings were quickly implemented by the plant. Moreover, measures representing an additional $1.5 million in savings, with a longer payback period, were also identified. They will be reviewed as soon as there is talk of replacing or upgrading important pieces of equipment.
More precisely, the process integration study showed that reject heat in the evaporator could be used to heat:
- Process hot water
- Boiler combustion air
- Boiler make-up water
- Buildings during wintertime
The study also highlighted other more traditional energy-saving opportunities, such as installing an economizer on the steam boiler to preheat domestic water while lowering combustion gas temperatures.
The process integration study was conducted jointly, in 2005, by CanmetENERGY and Maple Leaf staff. Financial assistance for the study was provided by Natural Resources Canada’s Office of Energy Efficiency (OEE).
To learn more about this project or for additional information about process integration and Pinch analysis, see the:
CanmetENERGY experts also conducted process integration studies in other Canadian food and drink plants. For more information, see the list of success stories for that industrial sector.
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