Environmentally friendly and energy-efficient

20.08.2009 A new, fully automatic Buhler pelleting system enables the Polish company Stelmet S.A. to utilize the wood remainders from its production process in an environmentally friendly and energy-efficient way. The Polish Stelmet company is one of Europe’s largest producers of garden architecture items made of pinewood and spruce. The term “garden architecture” refers to wood products for fencing, installing, and decorating gardens, garden plots, terraces, balconies, parks, and recreational areas. Such products include lattices, noise-abatement walls, pergola constructions, flower boxes, platforms, and entire garden sheds. They are retailed through do-it-yourself specialty stores and shopping malls under the trading chains’ own brand names or under the “Stelmet” brand. Stelmet holds a strong position in the markets of the EU member countries, especially France, Germany, Holland, the United Kingdom, Norway, and Turkey. The activities of Stelmet comprise all the processing stages from wood purchasing to packing of the finished wood products.

Keen environmental awareness
One of the priorities of the company Stelmet S.A. is being an environmentally aware company. Stelmet is dedicated to sustainable use of forest resources, protection of nature and respecting the rights of the people associated with the forest areas. In the Stelmet factories, the only raw material processed is therefore wood with the certification “Forest Stewardship Council FSC.” The FSC label guarantees that the wood comes from forests which are managed on the basis of precisely defined principles. The Forest Stewardship Council was established in 1993. It is committed to environmentally beneficial, socially responsible, and commercially sustainable forest management and promotes the marketing of wood that has been produced in an ecological and socially correct manner. The FSC label is subject to rigorous checks and also covers the processing chain. But the Stelmet factories do more than just process FSC-certified wood. Special attention is also paid to the direct envi- ronment by using chemical wood impregnation agents in a closed circuit.

Utilization of wood remainders
Stelmet S.A. made another step in its long-term development strategy in 2008, when it started up a completely new wood factory for processing garden wood and construction timber in the industrial park of Zielona Gora, a mid-size city in the western part of Poland. Stelmet S.A. invested some 35 million euros in the new factory, which at the same time became the company’s new headquarters. With its new factory, Stelmet is now capable of processing almost 150,000 cubic meters of wood in Zielona Gora.
Concurrently with its investment in the new production facility, Stelmet S.A. spent another 20 million euros on a pellet manufacturing plant. “With this, we are pursuing two goals,” says founder and managing director Stanislaw Bienkowski. “On the one hand, our goal is to utilize the wood remainders obtained during the production process in an environmentally friendly and energy-efficient way. Beside that, we of course also hope to generate a commercial benefit by creating a new business with the sale of pellets for heating and for industrial energy production.” The Stelmet boss is convinced that the new product will be a success.

Tight project schedule
Stelmet chose Buhler as a partner for constructing its new wood pellet factory. “We opted for Buhler because we wanted a partner for this novel technology that is thoroughly familiar with the processes involved and capable of developing adjustments on its own should the need arise,” explains deputy general manager Przemyslaw Bienkowski. “In addition, the Buhler engineering team guaranteed that the turnkey plant project would be completed within a tight schedule.”
The Buhler team started plant engineering work in July 2007. Despite the winter time that slowed down the construction of the new building, the plant was ready in March 2008. On May 12, 2008, start-up began. Everything was ready by the end of May 2008, when the first pellets were produced. Günter Lorenz, who coached the project as the area manager in charge for Buhler, remembers: “The project was a true challenge for us especially because of the tight schedule. But thanks to the good partnership with Stelmet and two partner companies we managed to meet all the defined deadlines.” Since the final commissioning of the plant in November 2008, pellet production has been humming smoothly and with a very high quality.

Energy from the cogeneration plant
The new wood pellet factory was built adjacent to the new production plant of Zielona Gora. The fully automated pellet production plant is generously sized so that a subsequent expansion will be easily pos- sible. The new facility is linked through a modern, dust-free conveying system directly with the main factory. This conveying system moves the wood remainders continuously from the production plant to the pellet factory.
The new pellet factory of Stelmet S.A. is made up of a number of indivi- dual systems. The conveying system transfers the moist wood chips into large intermediate storage bins. Then the wood chips are screened and coarsely ground in order to efficiently utilize the state-of-the-art downstream drying technology. The material is dried on a low-temperature belttype dryer, which ensures a reliable and energy-efficient process. The required drying energy, which is a significant cost factor in other such factories, is a “byproduct” from the new bark-fired cogeneration plant of the factory of Stelmet S.A. This system provides most of the electric power used in the pellet factory and thus decisively improves the total energy efficiency of the facility.

18 tons of pellets per hour
The heart of the new pellet factory of Stelmet S.A. is its dry fine-grinding system and pelleting plant. The dry wood chips are finely ground on large Buhler hammer mills. Special-purpose pellet mills then transform this “wood mash” into the finished wood pellets.
In the core unit of its new pellet factory, Stelmet S.A. can produce 18 metric tons of high-grade wood pellets an hour. For deliveries to households and for export, the pellets are packed into bags on a fully automatic bagging line. The bags are then also automatically palleted. Large customers are supplied in bulk with pellets shipped by special “tankers” and kippers.
The entire Stelmet pellet factory is controlled from a centralized loca- tion. The application of programmable logic controllers in conjunction with centralized monitoring enables the factory to be operated with little manpower.

The new pellet factory of Stelmet S.A. in Zielona Gora, Poland. The new pellet factory of Stelmet S.A. in Zielona Gora, Poland.