The Australian paper industry has been steadily improving its energy efficiency and environmental performance over recent years. Since 2014-15, direct emissions of greenhouse gases have been reduced by 5.1% and energy intensity of production fell by 5.3% (National Pulp and Paper Sustainability Report 2018).
Opportunities to save
Improve the efficiency of raw materials preparation
Proven energy-saving strategies include the use of cradle debarking, belt conveyors instead of pneumatic chip conveyors, automating chip handling and thickness screening, and using bar-type chip screens.
Energy can also be saved by increasing the percentage of recycled fibres in the papermaking process, which reduces the need for raw material preparation. Recycled inputs have increased substantially over the last decade as paper recovery rates continually improve.
Increase the efficiency of chemical pulping
Chemical pulping is a widely used process that can be made more efficient. For example, Investing in heat recovery for the pulping digester and the chemical bleaching process can save substantial energy costs.
Implement efficiency improvements in chemical recovery
There are numerous methods and technologies to improve the energy efficiency of chemical recovery, such as black liquor solids concentration, improved composite tubes in recovery furnaces, and utilising extended delignification and oxygen delignification.
Optimising the pulp washing process can help maximise chemical recovery while minimising the black liquor dilution factor. This saves energy by reducing the amount of water to be evaporated.
Enhance the efficiency of paper pressing
It is possible to save energy in paper pressing through using shoe (extended nip) press and gap formers, while optimising the paper machine's vacuum system.
Improve techniques for paper drying
Significant energy savings can be achieved through investing in better dryer control, heat recovery technologies and system optimisation. Traditional air-to-air heat recovery systems typically recover about 15% of the energy contained in the hood exhaust air, but this could be increased to 70%.
Upgrade and optimise technology
Paper and pulp mill energy efficiency can be further improved by plant wide opportunities, such as attention to optimising steam production, insulating pipework, improving compressed air systems, lighting replacement, equipment reliability improvements, and process rationalisation. Ensuring there are effective shut down procedures to reduce unnecessary energy overheads when production is stopped is also important.
For more information, see Pulp and paper opportunities to save.
New sensor and control systems
Allows access to real time data for optimisation of production systems and decisions, better cost and quality control, and reduction of waste.
Alternatives to fossil fuel can reduce costs and emissions. For example, greater use of biomass wastes, electrification of steam driven processes, and integration of renewable process heat (heat pumps and solar heating), are increasingly being adopted by innovative companies.
National Pulp and Paper Sustainability Report 2018 Industry Edge
Pulp and Paper Manufacturing Australian Industry and Skills Committee
Tracking Progress: Pulp and paper International Energy Agency