The baking of 800-gram loaves of bread typically consumes 1600 kWh of energy for 8000 loaves an hour. Whilst most of the energy is transferred into the product there is a significant amount of energy wasted into atmosphere in the flue gases.
Benchmarking – To understand the scope of the project, an initial energy survey was undertaken. A survey of the oven was completed to understand performance, with waste heat potential from exhaust ducts measured.
Measurements and calculations were also taken across the site to understand where heat was required. It was identified that a large amount of hot water was required, currently supplied by a gas boiler.
Process Optimisation – In consultation with the customer, it was proposed to firstly tune and optimise the existing equipment to ensure it was giving the best performance. It was then proposed to recover energy from the hot waste gases.
The first stage of this was to take heat from the flues and use the energy to pre-heat the Burner Combustion air. This provided a saving of around 7.5% of the gas consumption and had a value of £30,000*.
Heat Recovery – The second phase was to recover further energy from the waste gases and transfer the energy into hot water which could be reused throughout the factory. In total around 350 kWh of energy could be recovered and reused within the factory saving the customer more than £100,000 per year in fuel cost as well as the associated benefit of reducing carbon emissions.
The Energy Optimisation and Heat Recovery approach enabled the existing equipment to be operated to its best efficiency then our heat recovery solution was able to recover significant amounts of energy from a dirty process waste stream and return clean usable energy to the process and factory.
*UK Energy Costs 2021.