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German Efficiency: Sawmill Produces Little Waste, Powers Success with Biomass Energy
German Efficiency: HMS-HOLZ sawmill powers facility and sells energy back to the grid using innovative biomass plant design, company works to limit waste and improve log yield.
By Chaille Brindley
Date Posted: 8/1/2014
German Sawmill Relies on Biomass for Energy
HMS-HOLZ powers its facility and sells energy back to the grid using innovative biomass plant design.
HAGENOW, Germany – Waste nothing, use everything is the mantra for HMS-HOLZ in its Hagenow sawmill facility. With operations in Germany and Bavaria, HMS-HOLZ processes mostly pine, spruce, larch and Douglas fir into lumber and planed wood.
A key to the success of the company is its sustainability strategy to efficiently use every part of the log to produce products, waste material or energy.
“We have a small power generation facility. In Germany, we must create 10% of our energy from renewable energy,” said Martin Henne – senior controller for the Hagenow sawmill. “Wood is a good source to meet renewable energy targets.”
Unique Biomass Facility Design
In 2007, the Hagenow facility installed a Turboden T1500 biomass system. It uses primarily bark to fuel the burner which produces power that runs the facility as well as provides extra energy to sell back to the electricity grid. It also produces heat for use in the heat treatment chambers.
The Turboden system uses the principal of Organic Rankine Cycle (ORC). Instead of water steam, the ORC system vaporizes an organic fluid, characterized by a molecular mass higher than water. This leads to a slower rotation of the turbine and lower pressure and erosion of the metallic parts and blades.
Here is how the process works in detail. A heat source heats thermal oil to a high temperature, typically about 300°C, in a closed circuit. The hot thermal oil is drawn to and from the ORC module in closed circuit. In the ORC it evaporates the organic working fluid (silicone oil) of the ORC in a suitable heat exchanger system (pre-heater and evaporator). Then organic vapor expands in the turbine, producing mechanical energy, further transformed into electric energy through a generator. This vapor is then cooled by a fluid in a closed circuit and condensed. The water warms up at about 80 - 90°C, and it is used for different applications requiring heat. Finally, the condensed organic fluid is pumped back into the regenerator to close the circuit and restart the cycle.
The ORC approach has a number of advantages including: high turbine/thermodynamic cycle efficiency, turbine low mechanical stress, absence of moisture during the vapor expansion reducing blade erosion, simple start up procedures, automatic and continuous operation, simple maintenance procedure, no operator attendance required, long life of the plant (greater than 20 years) and no need to demineralize water.
These advantages are one reason that power plants based on ORC technology are quickly spreading around the world, according to Turboden.
Most of the newer mills in Germany have power plants because of the cost associated with transporting waste wood for energy production. Getting the right material consistency can be difficult at first. Henne commented, “Biomass plants are complicated; you need a really good burning material.”
Henne added, “The market has grown up very fast in Germany. Now everybody is looking to the best material, and you have to be aware of moisture, minerals and wood type. For example, too much sand in the mixture can cause the heating room to get hot on the inside, which makes for less efficient burning.”
While it is not an exact science, the staff at HMS-HOLZ has worked with Turboden to build a biomass plant that can run for 8,000 hours per year without stopping for maintenance.
Step-by-Step Process Eliminates Waste, Cuts to Order
The Hagenow sawmill processes softwood into a wide range of products – up to 600 different cutting patterns. Everything is produced to fulfill a specific order. Henne said, “We produce only after a product is ordered. We only cut what is needed, which minimizes waste and operational efficiency.”
Logs are debarked at the log yard to detect quality, look for insect problems and sort for specific requirements. Where a log is stored on the yard depends on the quality of the material. Logs are loaded onto a conveyor that feeds into the sawmill. Each log is measured (diameter and circumference) and turned to the correct position for optimum yield. The calculations are done using ALFHA software (http://www.alfha.de) designed to figure out the best cutting pattern for small and medium-sized sawmills. The system can trace the work order status through the entire operation to track production and ensure on-time orders.
Henne explained, “The ALFHA software helps the company fulfill orders and get the maximum yield out of each log. It can react to changing demand issues. It is very efficient and helps target the right production from each log.”
The plant uses circular saw technology because you don’t need a board edger like is common in many bandsaw facilities in the United States, explained Henne. He added, “In Germany bandsaw technology is very complicated. You need a good saw doctor, which tends to be very expensive. Circular technology is cheaper and produces tighter tolerances.”
More than 95% of sawmills in Germany use circular saw technology. This HMS-HOLZ plant processes about 1,000 cubic meters of round logs per day on a 10-hour shift.
The Hagenow facility uses a four sawhead SAB sawmill that can handle logs up to six meters in length. The sawhead moves from log to log to execute the best possible cut. At the last sawhead station a vertical circular saw makes one big cut through the center and four vertical cuts. Sideboards are sorted to quality at the end of the
main saw lines. Good center boards go out for further processing. An ALFHA scanner at the edger scans sideboards to control wane. The scanner decides which boards to put in various bins for storage.
About 50% of the material is kiln dried while the remainder is processed green. The plant has a complete Vecoplan transportation, sorting and screening system for sawdust and chips. Henne stated, “The Vecoplan system has run well without any problems. Its reliability is why the company chose to install a bigger system when the facility was upgraded.”
Chips are used for paper production while sawdust is sold to produce chip boards and presswood pellets.
Just like in the United States, one of the biggest problems is sourcing logs to feed the voracious appetite of the sawmill. Henne explained, “Private forest owners can’t bring enough wood out of the forests. They are waiting for prices to go up before harvesting more material.”
The capacity of this sawmill is too high compared to current supply levels. With about 60% of forests privately owned in Germany and restrictions on logging public land, the market is limited on how much can be harvested. Trees that are processed at HMS-HOLZ do exclusively come from sustainably cultivated forests.
A Strong Family Tradition
The history of HMS-HOLZ goes back to 1899 when Heinrich Martin Seuffert founded a sawmill in Kleinwallstadt/Main, Bavaria. His pioneering work as well as his initials are the basis for the family-owned company HMS-HOLZ.
The company’s history of the second generation was affected by the confusion of World War II. As a young man Adam Anton Seuffert had to leave his home and did not return to Kleinwallstadt until years after the end of the war. During this time, his wife Barbara Seuffert carried on the fate of the company as well as provided for her two children Anne Rose and Heinrich Anton.
At the end of the sixties Heinrich Anton Seuffert relocated the sawmill to a newly set up nearby industrial area. At the same time they specialized in softwood and significantly extended their capacity. Years later the Seuffert family bought the land where the Hagenow facility resides today.
The Hagenow plant currently has 64 staff and 15 office/administration personnel. This fourth generation family business has made a name for itself thanks to its focus on quality, custom dimension cutting and timely delivery. Its efficient power plant has the company poised to continue this tradition by adding sustainable energy production to its public reputation.