مصرف انرژی جهانی به علت اصطکاک در دستگاه های کاغذی

Calculations on the global energy consumption used to overcome friction in paper machines in terms of friction in motors, transmissions, pumps, blowers, agitators, pipes and the roll systems are presented. The following was concluded: – The energy consumed to overcome friction in a paper mill is in the range 15–25%. – Globally there were 8525 paper and paperboard machines in operation in 2012. One paper machine uses on an average 140 TJ of electrical energy per year. Of this 32% is consumed to overcome friction, 36% is used for the paper production and mass transportation and 32% is other losses. – The friction losses in an average paper machine are in total 44.8 TJ per year, and they are distributed as 32% due to friction in water-lubricated sliding in seals, doctor blades and fabric/support contacts, 23% due to friction in elastohydrodynamic rolling contacts, 22% due to friction in elastohydrodynamic rolling–sliding contacts, 15% due to friction in oil-lubricated seals and 8% due to friction in hydrodynamically lubricated contacts. – Worldwide 105,000 GWh electrical power was used in 2009 to overcome friction in paper machines. This equals to 381,000 TJ of annual energy consumption. – By taking advantage of new technology for friction reduction in paper machines, friction losses could be reduced by 11% in the short term (about 10 years), and by 23.6% in the long term (20–25 years). This would equal to annual worldwide economic savings of 2000 million euros and 4200 million euros; electricity savings of 36,000 and 78,000 GWh; and CO2 emission reduction of 10.6 million and 22.7 million tonnes. Potential mechanisms to reduce friction in paper machines include the use of low-friction and highly durable coatings, surface engineering including texturing, low-viscosity and low-shear lubricants and fluids, novel additives, new materials in seals, doctorblades and fabrics, as well as new designs.

Improving energy efficiency has become a global megatrend within all industrial sectors as well as in the entire society. The overall aim is to minimise the greenhouse gas emissions, ensure the energy security and improve the industrial output and competitiveness. In the end part of the production chain, the conscious customers in the industrialised countries have woken up by the threats of global warming, changed their consuming habits and started to demand green and sustainable products and services. The uncertainty about global fossil energy reserves and their availability in the long run is increasing the awareness for the development of clean and renewable energy resources and optimised energy use to prevent waste. Furthermore, the increasing energy prices in recent years have created a greater demand for improved energy efficiency to reduce operating costs and support sustainable competitiveness. The current energy landscape, research opportunities and pathways that can lead to a prosperous, sustainable and secure energy future for the world were recently reviewed by Chu and Majumdar [1]. They consider that solar and water-based energy generation and engineering of microbes to produce biofuels represent good examples of the major renewable alternatives. In a recent study Holmberg et al. [2] reviewed the economic and environmental impact of friction on energy consumption at global scale. They analysed in detail the energy loss sources and potential improvements in passenger cars and found that significant reductions in energy losses due to friction are possible. Advances in cost-effective technologies, such as tribological design, coatings, surface engineering, lubricant chemistry, tyres, braking and waste heat energy recovery, could potentially lead to fuel efficiency improvements of 20% in the short term (5–10 years) and more than 60% over the long term (15–25 years). In the present article we have chosen to focus on the energy losses due to friction in large, industrial process machines; here represented by the paper machine. We specifically focus on the electrical energy flow in a paper machine as this is largely used to overcome friction, whereas the heating in the paper making process relies on thermal energy from combustion processes.

We have studied the global energy consumption due to friction in paper machines and the following can be concluded: – Our study shows that 32% of the electrical energy and 9.6% of the total energy consumption in a paper machine goes to overcome friction. The energy consumed to overcome friction in the whole paper mill is in the range of 15–25%. – Globally there were 8525 paper and paperboard machines in operation 2012. One paper machine uses on average 140 TJ of electrical energy per year, of which 32% is consumed to overcome friction, 14% by viscous flow resistance, 12% by electrical losses, and 36% is used for the paper production, including 5% for paper formation by water removal, 3% for the slice jet acceleration in the head box, 23% for mass transportation and 5% for mixing. – The friction losses for the average paper machine are in total 44.8 TJ per year, and they are distributed as 32% from friction in water-lubricated sliding in seals, doctor blades and fabric/support contacts, 23% from friction in elastohydrodynamic rolling contacts, 22% from friction in elastohydrodynamic rolling–sliding contacts, 15% from friction in oil-lubricated seals and 8% from friction in hydrodynamically lubricated contacts. – Worldwide 105,000 GWh electrical power was used in 2009 to overcome friction in paper machines. This equals to 381,000 TJ/a of energy consumption. – By taking advantage of new technology for friction reduction in paper machines, friction losses could be reduced by 11% in the short term (about 10 years), and by 23.6% in the long term (20–25 years). This would equal to worldwide economic savings of 2000 million euros and 4200 million euros, respectively; electricity savings of 36,000 and 78,000 GWh, respectively; and CO2 emission reduction of 10.6 million and 22.7 million tonnes, respectively.