The work carried out consists in recovering the heat contained in the fumes leaving the kilns for baking biscuits and crackers in service at the factory of a leading multinational company operating in the bakery products sector. More precisely, the project concerns the fumes from four firing furnaces for a total of forty fireplaces. The recovery of thermal energy is carried out by means of two successive stages of heat exchange, specially dimensioned, designed and implemented. The first stage allows the temperature of superheated water to be raised from 115°C to 130°C. The superheated water is used for all the plant's process requirements (e.g. oil silos heating, diathermic oil heating, domestic hot water, water for washing, water for winter heating, etc.). The water is drawn from the return circuit before it reaches the central heating plant and after being heated it is fed back into the same circuit. The second stage of heat exchange was used to heat diathermic water at 70°C, which was used to integrate the microclimatic winter needs of some production departments. Under ex-ante conditions, all the heat required for the processes described was produced through natural gas boilers.
Results obtained:
- Thermal energy saving: 5.044.000 kWh/year
- Primary energy saving: 484 Toe/year
- Saving of natural gas: 578.560 scm/year
- CO2 not released into the atmosphere: 1.128 tons/year
- Payback intervention: about 18 months
The system has been equipped with a monitoring system able to measure and historicize the post-intervention consumption. This is essential for taking stock of and verifying the energy savings achieved.
The intervention has been analysed, designed and implemented by RENOVIS.
