.

Sägewerk Echtle GmbH & Co. KG

Overall planning

Nordrach (Black Forest), Germany

Operational since 12/2006

.

The plant

The Sägewerk Echtle GmbH & Co. KG operates a sawmill with processing of the produced lumber in Nordrach (Black Forest). The annual volume of roundwood (without bark) is approximately 45.000 fm/a. The demand for dried lumber has significantly increased in recent years, necessitating the company to expand its drying kiln capacity. Furthermore, heat is required for heating a new production hall. Therefore, an ORC cogeneration plant has been installed, which is intended for the energetic utilization of the sawmill’s own by-products and equipped with a thermal oil heater and an ORC system. The generated electricity is fed into the public grid based on the Renewable Energy Sources Act (EEG).

The technology

The facility is designed for the use of processed and unprocessed, untreated wood (total wood volume 16,000 t/a, such as sawmill residues like bark, planer shavings, sawdust, wood chips, as well as green and shrub trimmings). The newly constructed push floor is centrally located and allows for optimal filling with both internal and external fuels. The power plant building includes the combustion and boiler installation room, the machinery room for the ORC system, and the associated auxiliary rooms. The wood is combusted in the combustion and thermal oil heating system. An ORC system is used for electricity generation, which captures the heat energy generated in the thermal oil boiler through a heat exchanger. The silicone oil used in the ORC process requires less vaporization energy than, for example, water. Overall, the ORC process operates at a lower temperature level than the conventional water-steam process. The generated silicone oil vapor is passed through a turbine with a downstream generator for electricity generation. In a condensing heat exchanger, the silicone vapor is liquefied and returned for re-evaporation.

Technical data

Firing

Grate Combustion

Combustion heat capacity

5,2 MW

Fuel

Sawmill by-products, bark, green and landscape trimmings

Thermal oil heater

Rated power

4,4 MW

Boiler

Type

Three-pass boiler with vertical cylindrical radiation heating surfaces

Operating temperature

290 °C

Operating pressure

10 bar

Cogeneration plant

ORC process based on silicone oil with turbine and downstream generator

Operating temperature

270 °C

Electrical power

900 kW

Heat recovery

Steam condenser

Rated power

3,7 MW

Operating temperature

85 °C

Flue gas dedusting

Multicyclone, electrostatic precipitator