The 55-acre site, which makes canned baked beans, pasta, soup and puddings, is the largest food production facility in Europe.
Efficiencies have been achieved across the board through working closely with the Carbon Trust, utility manager Barry Aspey told FoodManufacture.co.uk.
However, the biggest savings have come from capturing and recycling waste heat from blanching (heating water to rehydrate dried beans) and steam-heating (sterilising) the beans in their cans, plus improved boiler efficiency.
During blanching, dust and debris from the beans accumulate in the water, which needs to be periodically drained off and replaced with ‘fresh’ hot water.
Heinz now uses the hot ‘blowdown’ water to heat new water for blanching via a heat exchanger. By opting for a plate system protected by a self-cleaning rotary filter, it has been able to prevent the debris removed during blanching from clogging up the system, said Aspey.
“This reduces the heat requirement by about three-quarters and largely removes the need to cool the effluent blowdown water before discharge. The heat exchanger has delivered impressive results and it gave us a return on investment in just two years.”
Meanwhile, the factory’s hydrostatic operator Peter Gwinnet has halved steam consumption in the factory’s hydrostatic (vertical) sterilisers by identifying a way to keep their two water streams – hot water at 80°C and cooler water at 40°C – separate.
Previously, the two streams were mixed and then sent for storage. When new water was required it was then heated back up to 80°C. Today, the cooler water is recovered to another water system.
Further work has focused on the rotary sterilisers, in which water is also segregated into high and low temperature streams, meaning heat from the ‘hot’ stream can be recovered and used to preheat other process water systems.
Further efficiency savings were generated by reducing the size of ‘bleed holes’ on sterilisers after discovering they were bigger than the legal 3mm minimum and were releasing more steam than necessary.
More efficient boilers
Separately, Heinz has improved the efficiency of its boilers through including a condensing economiser in its new energy centre, said head engineer Phil Crompton.
“Heinz is seeing a consistent overall thermal efficiency of over 90%, around 15% more efficient than the previous boiler house. The project gave a simple payback of 18-19 months, and the new energy centre has reduced emissions by 9,000t of carbon dioxide a year.”
Heinz is also exploring opportunities to produce power from waste and use more renewable energy (wind, solar) in a bid to meet its company-wide goal of reducing carbon emissions by 20% by 2015 (compared with 2005 levels), added Crompton.
“We are exploring the possibility of introducing anaerobic digestion. Reducing waste and increasing the use of renewable energy, this would help the factory achieve two of the company-wide sustainability goals. It could also save almost 3,200t of carbon dioxide a year at Kitt Green.”