Vast amounts of energy and water are used in the manufacture of tissue paper.
The fibrous substrate formed from pulp stock is passed over a Yankee cylinder, operating at 180°C for drying. The hot air impingement hoods, operating at up to 400°C, accelerate the drying process with the exhaust air vented to atmosphere.
Waste energy is presently used to heat pre – combustion air for the Yankee hood burners and the pre-heating of process water streams. However, many of the existing heat recovery systems are inefficient and Operational’s detailed surveys have identified energy can be more efficiently recovered to replace live steam and other process hot water uses within the mill, including:-
-The utilization of a waste heat steam generator; hot water to pre-heat combustion air; hot gas to water and water to water heat recovery.
-Steam generation plant installed between the Yankee dryer and the existing heat exchangers with a condensing heat exchanger replacing the existing under-performing installation
Benefits – 1300 kWh of steam generated at 12 bar and 1000 kWh of hot water at 70°C. Potential Energy savings of £ 420,000 per annum with a Return on Investment of approximately 2 years.