Central heat recovery system in an industrial laundry

The study assessed changes in energy, temporal, technological, environmental, and washing-quality parameters after introducing a central heat recovery system in an industrial laundry. Instrumental measurements, gravimetric and microbiological methods, textile mechanical testing, and calculations of energy-efficiency and carbon dioxide (CO2)-emission indicators were applied. Specific heat energy consumption decreased from 7.8 to 4.6 kWh/kg, while heat energy use for 100 t of laundry fell from 780 to 460 MWh. Recovered heat supplied 42% of the total heat demand, reducing steam-boiler load from 100% to 72% and shortening the washing cycle from 35 to 30 min. Washing-tunnel performance increased from 1000 to 1200 kg/h, and completed cycles per shift increased from 13 to 16. Annual natural gas consumption decreased from 430 to 300 thousand m³, and specific carbon dioxide emissions from 62 to 42 kg/t. Average moisture after drying declined from 6.5% to 4.8%, while laundry ready for folding increased from 78% to 92%. Protein- and fat-contaminant removal and whiteness also improved. A separate ozonation test increased microbial reduction but was not attributed to heat recovery. The integral energy efficiency index increased from 1.00 to 2.03.