|Energy efficiency in the swedish
pulp and paper industry
By Göran Bryntse, PhD in Paper Technology
Potential electricity savings in the swedish paper industry
More efficient mechanical pulp refining 3 TWh
Motivated consumption, 22 – 7 TWh = 15 TWh
Increased power generation potential
Black liquor gasification +10 TWh
Power generated 2006:
Back-pressure turbines 5,5 TWh
Total potential ca 20 TWh
Efficient thermo-mechanical pulp
Holmen and Metso is now reconstructing the TMP-plant in printing
paper mill Braviken.
There are three parts in the new technology:
1) Pretreatment of the chips
2) Control of the pressure in the refiner
3) Combination of HC- and LC-refining
If this technology is introduced in all printing paper mills the total
savings would be 2,25 TWh according to the Swedish Energy Authority
Efficient CTMP manufacturing
CTMP manufacturing for board and tissue qualities only needs about 500 kWh/ton according to results in Östrand CTMP mill outside Sundsvall.
Fors board mill in Dalarna needed 2005 about 1300 kWh/ton CTMP.
Soon they are down to about 600 kWh/ton.
Higher rotational speed in the refiner saves energy
Andritz delivers refiners with 2300 rpm instead of the conventional
1500 rpm technology. A reduction of more than 300 kWh/ton electric energy
was observed with no change in pulp quality.
More efficient pumping
According to an international survey from 2001, ”Pump life cycle costs: A Guide to LCC Analysis for pumping systems”, do pumps consume 17-20 % of all electricity produced. 30-50 % savings are possible.
Sulzer and Scanpump have recently developed more efficient pumps than
before, i.e. Sulzer Enersave and Scanpump BE serries, launched 2005.
Frequency controlled pumps are now cheaper than ever and profitable for almost all pumps in a pulp or paper mill.
About 8 TWh are consumed yearly by pumps in the Swedish pulp and paper
industry. 2 -3 TWh can be saved by introducing more efficient
Energy efficient fans
Fans in Europe consume more than 200 TWh/year electric energy. By using efficient fans with drive control 20 % of this energy can be saved.
Fans in the Swedish pulp and paper industry consumes about 2,5 TWh/year.
A new Swedish invention, the so called spiral fan, constructed in order
to use the so called Archimedes Spiral Principle, saves at least 15 % of
what a conventional fan consumes. Also, the fan is more quiet because it
does not generate any turbulent flow. A demo version is now operating at
Hallsta newsprint mill in Sweden.
More efficient motors
Motors are classified in different categories. The highest efficiency class among standard motors are Eff 1. Quite a noticeable saving could be reached by using these motors consequently in the pulp and paper industry.
However, due to a Demand Side Management program of IEA, where I participated, ABB developed their motors, called ” High performance” or ”Eff 1 plus”. These motors, who won the IEA competition in the beginning of this century, has about 15 % less losses than Eff 1 –motors.
The Swedish pulp and paper industry could save about 0,5 TWh by
consequent usage of ABBs High Performance motors.
The usage of pressurized air and vacuum should be optimized in the paper industry, thus decreasing energy demand.
Aspa Mill at lake Vättern only needs about 580 kWh/ ton softwood
kraft pulp. This can be compared with the KAM2 model mill, presented by
the industry, ending up in 712 kWh/ton.
Beating energy of the pulp can be decreased substantially. Yearly about 1 TWh is consumed in Sweden while beating the pulp.
By the so called Finebar method, allowing lower specific edge power in the beating equipment, combined with other optimized control, about 30 % of the beating energy can be saved.
The Swedish pulp and paper industry can be completely self sufficient in energy supply. This industry as a whole thus does not need any external electricity supply from the grid.
The Swedish and the Finnish pulp and paper industry are similar to a
large extent. Therefore, the Finnish pulp and paper industry, as well as
the Swedish, does not need nuclear power.