Waste-heat-based district heating network
Back in 2000, Getzner Textil started preparing to implement the use of waste heat: a sustainable project which today is said to provide the environment, consumers and Getzner Textil as the energy supplier with a three-way win-win situation.
In 2001, a district heating network was constructed to supply numerous public buildings in the immediate vicinity of the company headquarters. Getzner Textil bore the costs of connecting the consumers to the existing heating systems, which it was decided to retain in case of emergencies.
Today, the network comprises approx. 2000 metres of pipework that supplies seven consumers, each with a demand of 80 to 1000 kWh of heat. Getzner Textil has two sources of waste heat: compressors and exhaust gas heat exchangers on the steam boiler systems. At peak times, any heat shortfall is covered by the internal stream mains with the aid of a steam to water heat exchanger. Of the entire heat input, 3.7 GWh are used internally each year, and the rest is made available to public building.
Key district heating figures
- Annual heat input into the district heating network of 8.2 GWh
- A total of 4.5 GWh for the district heating of public buildings per annum
- A total of 3.7 GWh per annum for internal use
- Investment costs of 1,400,000 euros, of which 320,000 euros came from funding
We set a good example
The targeted measures used in our energy-saving project reduced the electricity consumption of the compressed air system by a quarter, a saving of around 1,2 GWh per year.
The operation uses compressed air for compressed air weaving machines and this must be guaranteed 365 days a year. The compressed air supply is classed as a “key machine” and its operation must be 100 % guaranteed.
Its annual electricity consumption is approx. 7.2 GWh, and the compressors operate for approx. 30,500 hours each year. The pressure of the entire network is 7 bar, whereby a pressure of 5.5 bar is sufficient for the weaving mill and a pressure of 6.5 bar for the boiler house. The average compressed air requirement is 85 Nm³ per minute. The system is fed by two compressed air stations. There are five compressors in the weaving mill station, all of which are controlled by an “Air Manager” and equipped with a heat recovery function. The waste heat is fed into the heating network. Two reserve compressors in the boiler house station are not fitted with a heat recovery function, as they are only used during maintenance or in the event of a fault, or to cover weekends and public holidays.
The network that had previously been supplied by both compressed air stations was disconnected and the pressure level of the weaving mill station adjusted to 5.5 bar and that of the boiler house station to 6.5 bar. The existing controller was optimised.
A new, efficient compressor with a heat recovery function was installed in the weaving mill station. The existing compressors were retained for redundancy purposes to safeguard the compressed air supply and to cover peak loads. The weaving mill station no longer contributes to the compressed air supply of the high-pressure network, which is now covered entirely by the boiler house station. Since this section also has to be fail-safe, these compressors have also been upgraded and equipped with a heat recovery function. The controller for the new compressors has been installed and adjusted for the existing compressors.
All compressors have been integrated into the heating system to make use of the waste heat.
- Specific energy use has been reduced by 17 %.
- Annual energy saving of more than 1,200,000 kWh.
- Annual cost saving of more than 110,000 euros.