In 2013, Australia’s largest water
utility, Sydney Water, purchased three GE Turbo
blowers to
upgrade their PD blowers at Warriewood WWTP. Warriewood Wastewater Treatment
Plant serves an area of 25 square kilometres or over 63 000 people. The local
population is expected to grow by around 11,000 over the next two decades and
the upgrade was performed to cater for the population growth.
Sydney Water is committed to energy efficiency. They run a number of energy
efficiency programs, providing savings over 15,000 MWh per year. One of the
programs is to minimize power used in the aeration process at wastewater
treatment plants. GE Turbo blowers were purchased in line with this program
because of their high efficiency and turndown. Also, Sydney Water requires all
equipment to be supplied with standard off the shelf hardware, that is, they
have a no ‘black box’ controller policy. One other feature Sydney Water required
was for the ability of the turbo blowers to run together with existing PD
blowers. The GE TurboMax blowers met all these criteria.
After a competitive tender process between turbo blower supply companies meeting
Sydney Water’s requirements, three GE Energy Turbo Blower Packages model
RH-07506SSAA rated for 75 HP, were ordered.
The blowers were installed in May 2013 and Sydney Water retained a PD blower at
Warriewood to allow for direct efficiency comparisons. Actual measurements shown
in the table below confirmed energy savings of 16% to 24% were achieved
depending on flow rate. The retained PD blower was completely rebuilt to new
blower tolerances. As such the turbo versus PD blower comparison is a true
comparison, not one where the PD is well worn.
[Sydney Water control specialists state that they value ease of installation (Modbus
communications require no hard wire back up and deliver all necessary values and
control parameters, allowing savings on installation costs). Their service
technicians appreciate the low maintenance, low noise and virtually no vibration
and the fact that GE turbo blowers can be installed in parallel with PD blower
on a common manifold.
Sydney Water is now looking at retiring all its continuous operation PD blowers
and replacing them with high-speed turbo blowers.
Depending on the requirements, return on investment on the Turbo blowers’
installation maybe less than 2 years and longevity is predicted to be at least
20 years, while energy savings reach up to 30%.
In addition to the energy savings, turbo blowers offer other advantages. They
are compact, lightweight and have minimal installation requirements. In contrast
to PD blowers, no civil works such as plinths and foundation bolts are required
and the comparatively smaller footprint means direct replacements are often
straightforward. Low noise and vibration levels mean comfort both for workers
and for people living in the surrounding area. Turbo units are durable,
reliable, and require minimum maintenance - apart from monthly checks and
clean-ups of filters and replenishing of water (water cooling on 200 HP and
above models) they require no attention and no dedicated personnel. Controls on
Turbo Blowers are of Allen Bradley or KEB manufacture which means spares and
technicians are available worldwide. For harsh Australian conditions,
environmental durability is also of importance; GE Turbo Blowers are capable of
withstanding weather extremes and are rated for duty at 55°C.
Bump-type air foil bearing design ensures the blower delivers greater stability
and load bearing capacity compared to leaf-type air foil bearings and can
provide instant stop start operation. In case of a soft failure (if a bearing
failure occurs, the bearing foils restrain the shaft assembly from excessive
movement), only bearings and shaft surfaces are affected, and they are
inexpensive to replace. They also do not require lubrication.
The last question remains – with the initial asset price of turbo units somewhat
higher than that of a standard PD blower, can you afford it? With the
installation and energy savings to be made and major maintenance costs
eliminated, life cycle costs are often significantly lower.