DEEP

The paper industry still relies heavily on fossil fuels, especially natural gas, to generate steam used in various processes, mainly for paper drying. To decarbonise paper production, several alternative energy sources and technologies are either already available or are currently under development. Among these, high-temperature heat pumps appear particularly promising with respect to energy- and cost-efficient decarbonisation.

Industrial heat pumps capable of supplying temperatures significantly above 100 °C are still relatively novel, and the heating capacities implemented in the sector to date are well below of those required at the Heinzel Group's paper production site. Higher heating capacities necessitate the development of customised heat pump integration concepts.

The aim of DEEP project is to develop an efficient and flexible steam supply concept for a paper machine, by recovering a large share of the moist exhaust air and converting it into steam via a high-temperature heat pump system, which then will be used to heat the drying cylinders. In addition, the project is investigating potential for efficiency and flexibility improvements in steam supply and waste heat utilisation.

Project Progress

In an initial phase, key parameters, boundary conditions, and potentials for enhanced waste heat recovery are identified. A comprehensive database established, documenting steam demand and available waste heat for various paper grades.

Subsequently, multiple technical options for integration of a high-temperature heat pump system into the existing paper production infrastructure are systematically analysed. Emphasis is placed on different heat recovery strategies, the flexibility requirements of the drying unit, and the specific operational demands associated to different paper grades. These integration options are evaluated with respect to environmental impact and economic viability.

Models of paper drying and heat pump systems are developed, validated and applied. Based on these models, an optimised operating strategy is formulated and the concept for a large-scale implementation is developed.

(Expected) Results

The DEEP project should lead to the following results:

• Comprehensive knowledge of usable waste heat and efficiency improvement potentials across the production of various paper grades
• Techno-economic concept for the implementation of a steam-generating high-temperature heat pump, that leads to a medium-term CO₂ reduction of more than 50,000 tons per year
• Dissemination of the conducted work and achieved results among scientific and industrial stakeholders