HOW ONE OEM INNOVATED

Lots Of Energy Austrian Firm Has It

For more than 55 years, the Lower Austria-based company Polytechnik has been specializing in power generation from biomass. With more than 3,300 installations worldwide, the company has evolved into a global player and leading supplier of customized solutions for any application, whether it’s warm water, thermal oil or steam, from cogeneration plants to process heat generators and municipal heating networks.

The Polytechnik Group has 240 employees and, along with its main factory in Weissenbach, Austria, and its subsidiary in Auenwald, Germany, it has branch offices in Hungary, Switzerland, France, Poland, Russia, Romania, Belarus, China and Australia/New Zealand.

With its independent subsidiary, Polytechnik has been active in Australia and New Zealand for more than 10 years and now has a multitude of installations there.

New Zealand’s forests cover 10.1 million ha and 38% of its total area. In 2019, around 37 million m³ of timber was harvested. One important local consumer is the sawmill industry, which produced 4.4 million m3 of sawn timber in 2019. Despite the great distances and restrictions caused by the pandemic, Polytechnik successfully completed projects in New Zealand, which adapted an extremely rigid containment strategy.

WET Gisborne

Gisborne has become the center of a potential “revolution” in timber processing and housing construction in New Zealand. The plant of WET (wood engineering technology) produces OEL (optimized engineered lumber), which is 40% stronger than comparable standard constructional lumber. OEL is made from thin lumber strips that are fingerjointed and laminated together. By laminating, its stiffness and strength are improved and therefore timber of lower quality and with smaller diameters can be used for a highquality construction product.

WET’s technology turns untreated round timber, which otherwise would be sent abroad, into an innovative, high-quality product.

With the start of the construction of a second line, which will more than double the site’s capacity, a decision was made for the installation of a Polytechnik thermal oil plant. The plant, which is currently being built, will supply the site’s drying chambers as well as other consumers with 235°C thermal oil.

With this installation, the company achieves independence from the neighboring sawmill, which currently supplies heat to the drying chambers, and emissions are reduced by more than 90% compared to the existing plant due to the highly efficient combustion system combined with an electrostatic precipitator.

Residual materials from the sawmill, mainly very wet wood shavings, as well as waste material from the production, like wood chips, are used as fuel.

In order to keep the efficiency for the operational time of 50 weeks per year at an optimal value, Polytechnik employs a patented cleaning system which keeps the thermal oil boiler’s heating surfaces free of fly ash and thereby reduces the operating cost and increases the service life of the thermal oil boiler.

24 Wood Bioenergy / December 2021 Pan Pac

In 2017, the Japanese company Pan Pac Forest Products finished a $24 million refurbishment of its sawmill in Milburn, NZ. Production was doubled from 50,000 m3 to 100,000 m3 of sawn timber per year.

The plant in Milburn, south of Dunedin, close to Milton, is using some of the newest and most environmentally friendly equipment, from the fuel source to the biomass heating plant with exhaust gas cleaning and the wood drying plant with cutting-edge technology.

In Milburn, 100% pine trees are processed into lumber, which currently is intended exclusively for export to Asian customers. The pine is sourced from the surrounding area of Otago, from small forest properties as well as from City Forests, Matariki and Wenita.

The lumber is used for furniture, housings or boxes, including fingerjointed and edge-glued products. Most

sales go to Vietnam, Taiwan, China and Indonesia, while the wood chips are supplied to Dongwha’s MDF plant south of Gore. Polytechnik’s plant, which is specifically designed for the operation with wet waste material from pine trees with up to 65% water content from the sawmill, is fueled almost exclusively with wood shavings and bark in order to heat the water in the boiler up to 165°C, which then in turn is used to heat up the 60 m long continuous drying chamber to 95°C. Here, up to 90 m3 of wet wood shavings and bark are used as energy source every day.

The installation of the hot water plant with the adiabatic low-NOX combustion chamber and electrostatic precipitator from Polytechnik set new standards for efficiency and emissions for the New Zealand sawmill industry in 2017.

Nelson Forests

Nelson Forests was acquired in 2018 by OneFortyOne, a trans-Tasman business operating forests and mills in Australia and New Zealand. OneFortyOne manages 80,000 hectares of sustainable forest plantations in Nelson Tasman and Marlborough in New Zealand and operates a modern sawmill in Kaituna near Blenheim, where the pine logs are processed. Additionally, timber from certified sustainable plantations is processed in the Jubilee sawmill in Mt. Gambier, Australia.

The combined sales of round logs from Australia and New Zealand amount to more than 2 million m3/year, with the majority of the round logs being sold within the country in order to support jobs and local processing. Lumber sales from the plant in Kaituna amount to over 400,000 m3. The produced goods are mainly used for houses, sun decks, fences and furniture.

Since 2017, the site’s drying chambers needed for drying the lumber are supplied with saturated steam by a Polytechnik biomass plant, which heats up the ambient air to 95°C for the operation of the drying chambers.

The installation of an innovative combustion chamber and heat exchanger concept, which allows the staging and targeted insertion of the combustion air necessary for the combustion of very wet wood shavings, made it possible to decommission two of the site’s old boiler plants, which in turn led to a significant increase in availability and a dramatic reduction of emissions.

After almost 30 years, the site’s four boiler operators were finally able to tend to other tasks, as the Polytechnik boiler plant, which was installed in 2016, can be monitored and operated mainly remotely and without permanent supervision. The necessary tests of the steam boiler plant are carried out at least every 72 hours in accordance with the applicable regulations.

Christchurch

The successful experience with Polytechnik plants in the wood industry have also opened doors to other wood energy applications in New Zealand. For example, Polytechnik was able to win the tender for the heating supply of a large hospital.

In Christchurch, the second-largest city in New Zealand, where Polytechnik has installed six boiler plants in past years, a 15.6 MW heating supply system for the hospital is being constructed which will use otherwise unused wood residues from the forestry sector and the surrounding sawmills as fuel. Here, Polytechnik’s engineers have to fulfil special requirements. The plant has to meet the country’s strict requirements regarding earthquakes in order to reliably supply the hospital with heat and steam even after a strong earthquake.

According to the Minister for Climate Change, James Shaw, “The new biomass heating plant will help to significantly reduce CO2 emissions and to decommission the current coal boilers.” The plant will be put in operation in early 2022.

Article and photos submitted by Polytechnik.

December 2021 / Wood Bioenergy 25