Tissue Paper Manufacturing
Waste heat recovery at paper and tissue mill.
A paper and tissue mill had a dryer oven exhaust in excess of 400°C with high water content and some fibres, so Operational was approached to recover waste heat energy.
Vast amounts of energy and water are used in the manufacture of tissue paper. Once a fibrous substrate has been formed from the pulp stock, it is passed over a Yankee cylinder for drying. These cylinders are heated internally to a temperature of around 180°C using 10 bar steam. Around the Yankee, hot air impingement hoods are arranged to further accelerate the drying process. These dryers typically operate at a temperature in excess of 400°C. Exhaust air is then drawn away from the dryer hood.
Some of the waste energy from this exhaust flow is used to heat pre – combustion air prior to the Yankee hood burners. In some installations there is further heat recovery into the process water stream. Many of the existing heat recovery systems are inefficient and in poor condition.
Based upon numerous detailed surveys, Operational has identified that more energy can be recovered more efficiently to replace live steam and other process hot water within the mill. Detailed analysis of the process and applying Operational’s experience in heat recovery brings focus to the best heat recovery technology and targets the highest ROI.
Solutions include utilization of waste heat steam generator; heat to combustion air; hot gas to water and water to water heat recovery. All solutions have process by- passes and excellent cleaning and access features.
- Industry: Paper and Tissue Mills
- Initial Situation: Dryer oven exhaust in excess of 400°C with high water content and some fibres
- Solutions: Steam generation plant installed between Yankee and existing heat exchangers with condensing heat exchanger replacing existing under-performing installation
- Benefits Achieved for Clients: 1300 kWh of steam generated at 12 bar. 1000 kWh of hot water produced at 70°C. Value of energy recovered = £ 420,000 per year. Return on Investment in less than 2 years.