The 900 square kilometer catchment area contains the regional capital Linz, 39 neighboring municipalities and a number of Austria’s major industrial companies. The search for a solution for new compressor had been ongoing for some time, but plans accelerated when the plant’s operations teams heard positive reports on the performance of Sulzer’s HST turbocompressors recently installed 130 km away at Salzburg’s main wastewater treatment facility.
Until the middle of last year, aging blowers were a constant headache for the operations team at the Linz-Asten sewage treatment works. The site’s integrally-geared, single-stage centrifugal blowers were temperamental and failure-prone, with absorbing around €40,000 a year in maintenance costs. The 20-year old blowers were noisy too; so loud that one could not work in this area without powerful hearing protection.
After a competitive tender process, the contract to replace the blowers was awarded to Sulzer. To allow operation of the plant to continue uninterrupted during the upgrade process, the new Sulzer’s HST40 compressors were installed in a purpose-built above-ground, single story compressor house. This approach was made possible by the low operating noise of the Sulzer compressors, which produce only 70 dB(A), compared to the 100 dB(A) generated by the old units.
The new blower house and pipework were designed to accommodate six HST40 units, with four installed during the initial phase of the project, to be operated in parallel with two of the existing blowers. That approach was chosen to enable a smooth transition to HST technology. To accommodate for the old blowers, which were slower to reach full speed, some smart adaptations to the control systems were made to ensure that they would operate in sync with the fast-starting HST turbo compressors.
The installation proceeded according to schedule and the four HST compressors were brought into operation with the changeover from the old blowers taking just 10 hours. Following on from this, the two final turbo compressors have also been installed and commissioned.
The greater energy efficiency of the HST units has had a significant impact on energy costs. Energy consumption at the site is on track to fall by more than 6,200 kWh per day. Combined with the maintenance cost reductions, that should save the facility around €175,000 per year, while reducing annual carbon emissions by more than 580 tonnes.