Bioenergi started producing wood pellets in 1998 and today is one of Sweden’s largest wood pellet manufacturers. The company has one of the most modern production facilities in Europe. The factory with 17 employees is located in Luleå, Sweden.
Production process of wood pellets
In the past, Bioenergi used a decanter centrifuge to separate the wood fibres. This process has some drawbacks such as high energy consumption and frequent maintenance. A further increase in maintenance costs, prompted Bioenergi to look for a better solution. A company visit allowed him to learn about the Läckeby Roto-Sieve model RS24. Läntmannen Agroenergi had installed it to replace a Rotapass sieve. The Roto-Sieve model RS24 proved to be very reliable and simple. A round of checking references later, Bioenergi decided to proceed with the purchase of a Läckeby Roto-Sieve® drum sieve, with a conveyor screw.
Separation and dewatering of wood chips for further reuse
A process gas pipeline leaves from the nearby SSAB steel plant, which first passes through the Lulekraft energy plant, where a lot of energy is recovered. When leaving the Lulekraft energy plant, the process gas still has a temperature of 450 °C and is piped directly to the large drying drum at the Bioenergi plant, where wood pellets are dried using this hot gas. After passing through the drying drum, the gas goes to the cooling tower, where the temperature is reduced from 450 to 90 °C. During the drying process of the wood pellets in the large drum, a lot of wood dust and wood particles enter the cooling water via the gas.
High-performance drum screen in a demanding production process
The process is a closed system, so these dust and wood particles must be filtered out of the water again. The Läckeby Roto-Sieve® drum sieve takes care of sieving out this wood dust and wood particles. The temperature of the water is around 60 °C after passing through the drum sieve. The sieved water then returns to the closed system. The Läckeby conveyor screw SCP 220 then takes care of further dewatering of the removed wood particles. The filtered and dewatered wood particles return to the production process, to end up as wood pellets.
Success story
After 1 year in operation, manager Fredrik Nilsson can look back with satisfaction: the decision to install the Läckeby drum screen was a success. “In the beginning, we used a drum with a 1.25 mm perforation, only to switch to a drum with a 1.0 mm perforation after some time. That’s how we arrived at an optimal result,” says Fredrik. As an operations manager, Fredrik can really appreciate the simple and easily accessible design of the Roto-Sieve drum screen. Moreover, the Läckeby solution consumes 80% less energy compared to the previous centrifuge.
Working together for an optimal solution
The deployment of a Läckeby Roto-Sieve® drum screen on such an installation had never been tested before. Läckeby has been manufacturing drum screens since the 1960s and has successfully operated more than 5300 drum screens. But never before in wood pellet production. At first stage, some problems therefore surfaced, but soon some special modifications could be made. This to fully meet the special requirements of wood pellet production. More specifically, this concerns high temperatures and filter material with a high content of sticky subtances, such as resin. This led to the development of a special version of the drum screen. This special version of the Roto-Sieve drum screen is meanwhile achieving good results at both Bioenergi in Luleå and Scandbio’s wood pellet plant in Kammarp.
“Our goal is to continuously improve our production system and steadily expand our production. Implementing Läckeby’s solution is quite a step in the right direction. It was definitely a good decision to replace our old centrifuge with a Roto-Sieve drum screen.” says Conny Holmberg, director of Bioenergi i Luleå A.
Focus on the result
Task and Läckeby not only supply equipment, we like to think along with the customer to provide a tailor-made solution. Together, we come to a result that allows you to produce efficiently and cost-effectively, so you don’t have to spend time on faltering equipment on your production lines and endless servicing.
You focus on your product, we focus on the waste and process water!
