A more sustainable future for wood drying

A more sustainable future for wood drying

The operating costs and environmental impacts of sawmills can be reduced with advanced technological solutions.

In spring 2020, the Finnish Sawmills Association started to develop a road map for low-carbon operations in the industry. It will be implemented in cooperation with Natural Resources Institute Finland. The roadmap is the industry’s way of meeting and committing to the Finnish government’s goal of achieving a carbon-neutral Finland.

Potential for significant savings

The carbon footprint of the sawmill industry is in itself relatively small, with more than 9 million tonnes of CO2 being absorbed annually into the products of the industry. This is about 20 times more than the CO2 emissions from production. However, according to the low-carbon road map estimate, with investments in sawmills it would be possible to further reduce their carbon footprint by as much as 82 % of the current level by 2040. Most of the emissions from the sawmill industry result from logistics, but other areas are also relevant to the overall situation.

Harsh conditions sets requirements for motors

There are almost 80 industrial sawmills in Finland. Kilns are the largest energy consumer in sawmills, and their operating conditions are highly demanding. The drying temperature is usually below 90 °C, but sometimes even higher, up to 120 °C. Such environments demand a great deal from motors, and standard industrial motors are not even suitable for use under such conditions.

The motors rotate fans that circulate the air inside the kiln. The reliable operation of motors is critically important, as motor breakdowns would result in long delays in production. Motors can also have an impact on the operating costs and environmental impacts of sawmills. Energy efficiency in kilns, which are highly energy-intensive, can be improved with technological solutions that comply with current requirements.

ABB SynRM motors for wood drying kilns 

ABB has over 100 years of experience in engines for demanding environments. We were one of the first manufacturers of synchronous reluctance (SynRM) motors, starting in 2011. These motors have a coil temperature of up to 30 °C and bearings up to 15 °C lower in temperature than those of induction motors. This makes them an excellent solution for the harsh conditions of drying plants: due to the lower temperature, the winding insulation lasts four to eight times longer, and the lifespan of the bearing lubricant doubles. The motors are manufactured in an environmentally friendly manner without the use of components such as permanent magnets that require the use of rare earth materials. That is why they are also easy to maintain, as the simple design does not require specialist workshops.

SynRM IE5 motors have excellent partial load efficiency, and if the drying process permits energy consumption can also be significantly lowered by controlling the blowing power with a drive. ABB motors used in wood kilns also have a special coating that protects the motor from the effects of the hot, humid and corrosive environment.

SynRM synchronous motors can therefore bring many benefits for kilns. As the life span of the motors is extended and the need for downtime and maintenance is reduced, the operating costs and environmental impact of the sawmills are reduced.

The energy saved could be used to power electric cars, for example. Compared to IE2-class 30 kW motors, 7,500 hours of use of 30 kW IE5 motors save enough energy to charge a hybrid car more than 60,000 times (assuming a 13.5 kWh battery with 90% charging efficiency), and would enable driving a distance of more than 4 million kilometers per year using electricity alone. In practice, this could also mean charging more than 60 hybrid cars during a shift year after year, which could make carbon-free commuting possible for staff.

Compared to lower-efficiency motors, the payback period for synchronous reluctance motors is very short – even less than a year – and the difference in the cost of electricity consumption for a pair of continuous kilns could be a six-figure sum over the lifespan of the motors. They are also mechanically compatible with older motors, so only a partial modernization of the plant is also possible.

SynRM motors for kiln conditions are manufactured at ABB’s Motors and Generators factory in Vaasa. Energy-efficient ABB IE5 SynRM motors are suited to many purposes in other industries as well.

IE5 SynRM motors offer increased energy efficiency, improved sustainability and enhanced reliability.
IE5 SynRM motors offer increased energy efficiency, improved sustainability and enhanced reliability.

Text: Olli-Petteri Karjalainen, Key Account Manager, ABB Finland

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