One of the World’s First High-Availability Wood Gasification Plants

Solution

Together with Rockwell Automation, Schiefer built a wood gasification plant which – along with producing energy – has attracted a lot of attention abroad. And with 8,300 productive hours of operation per year it's hardly surprising – that's an unusually high level of availability. It's almost 95 per cent of the plant's total capacity and a performance most other wood gasification operators can only dream of. This success prompted Schiefer to think about diversifying his farming business by developing wood gasification plants for other companies.

“We developed the entire system ourselves, from the reactor down to the last filter for gas cleaning,” says Schiefer, visibly proud of a system that produces up to 200 kilowatts electrical and up to 400 kilowatts thermal energy per hour. The farmer can more or less leave the combined heat and power plant to get on with its job, thanks to the Allen-Bradley® CompactLogix™ system that manages the automation, including the heating technology, wood and maize drying and energy supply to the grid.

According to Schiefer, the key to achieving high availability in a wood gasification plant is accurate zone control within the reactor. “The reactor's ventilation is located in the oxidation zone,” he explains. “That's where CompactLogix makes sure that the zone, which is the hottest, does not rise due to variations in materials or humidity. It does that by adjusting the ventilation levels accordingly.”

He believes that as long as the ventilation is right and there's perfect coordination between the four reactor zones – drying, pyrolysis (carbonisation), oxidation and reduction – the stability issue can solve itself.

Fine-Tuning Makes All the Difference

The system requires precise fine-tuning, which is handled by the Allen-Bradley control system and by the Walking Floor based drying technique, which was developed by Schiefer. “The higher the humidity of the chopped wood, the more water will evaporate from it, so the dryer is adjusted to move forward more slowly.” This procedure contributes to better safety and reliability and is so effective that it's being talked about throughout Europe.

In the meantime, more modular wood gasification power plants in Germany, Italy and Slovakia have been installed. Also, there were very high expectations placed on the technology and with the brand Xylogas® found. The advice, support and expertise of Mr. Schiefer is another important aspect for customers, who can rely on his experience and thus save a lot of time and money.

Meanwhile, the Xylogas brand has established itself in the market and is especially known for quality and performance far beyond the borders of Austria. Additional product lines are developed and adapted to the new segment requirements. As there are still millions of people worldwide who have no access to electric power. Xylogas want to develop technology for these areas and so become a global player in the alternate segment.

Results

A plant in Sterzing/South Tyrol is delivering on its promises: After overall completion 900kW electrical power shall be supplied to the official power grid in Italy. 1570kW of thermal energy to the local grid.

Within this plant, the order of command is clear – the Allen-Bradley components call the shots. They're headed up by a CompactLogix controller from the 1768 series with a L43 CPU. This manages the flow of material from the silo to the reactor as well as the particle filtering and the drying systems. It also monitors the critical gas cleaning and production processes and fine-tunes all the action based on data provided by 1734 Point I/O™.

Erwin Schiefer is particularly impressed with the Allen-Bradley PowerFlex® 40 and 70 AC drives that manage a variety of pumps, drives and compressors, and with the Factory Talk View Studio visualisation system. He and his team can take a closer look at the system via a secure VPN connection whenever necessary, carrying out remote diagnostics and maintenance via EtherNet/IP. But that's something that is rarely needed, thanks to sophisticated automation technology from Rockwell Automation.