Aeration blowers have an important task in wastewater treatment, but their handicap is high energy consumption. Houston, Texas based company, HSI, introduced in early 2008 the air bearing HT series blower, which can reduce energy costs by 20-40 %. VACON AC drives are used for speed control.

1. Reference Story
turbo blowers save energy
in water treatment
HSI* offers tomorrow’s technology today
Aeration blowers have an important task in wastewater treat- Matching the blower speed to the aeration require-
ment, but their handicap is high energy consumption. Hous- ment
ton, Texas based company, HSI, introduced in early 2008 the
air bearing HT series blower, which can reduce energy costs In the light of the current economic situation across the globe,
by 20-40 %. Vacon AC drives are used for speed control. municipalities are exploring all avenues to minimize operat-
ing costs and make their facilities more energy efficient. One
Sewage, or domestic wastewater, treatment is the process of the largest consumers of energy at the plant is the aeration
of removing contaminants from wastewater and household blowers. These blowers are typically variable torque applica-
sewage, including surface runoff water. It includes physical, tions that benefit from ‘affinity laws’, which state that ‘power
chemical and biological processes to remove these contami- varies with the cube of the speed’. In laymen’s terms, slow-
nants. Its primary goal is to produce a waste stream of liquid ing the speed down 20 % will reduce power by 50 %. So the
and solid waste (sludge) that is suitable for discharge back objective is to match the blower speed to the actual aeration
into the environment. requirement, and this is also true with any centrifugal pump
application throughout the plant.
One of the most important parts of the process is aeration.
HSI Multistage blowers and High Speed Turbo blowers are HSI has been able to help municipalities in this quest to be
used to shake up the sewage and expose it to the air. This more “green”, introducing the air bearing HT series blower to
causes some of the dissolved gases, such as hydrogen sulfide replace the old positive displacement or centrifugal blowers
with its foul taste and smell, to be released from the water. used for their aeration systems.
The wastewater then enters a series of long, parallel concrete
tanks that are divided into two sections. In the first section, The City of Louisville, Colorado is one of many such munici-
air is pumped through the water. As organic matter decays, palities that have joined the “green” technology movement
it uses up oxygen, and aeration replenishes the oxygen. Bub- and purchased HSI High Speed Turbo blowers for its waste-
bling oxygen through the water also keeps the organic mate- water treatment facility. The decision to purchase the High
rial suspended, while it forces grit such as coffee grounds, Speed Turbo from HSI was based on quality and the annual
sand and other small dense particles to settle at the bottom energy savings.
of the tank, from where it is removed and taken to landfills.

2. “The wastewater treatment facility is saving 25-30 % in ener-
gy and that will pay off the equipment within 5-6 years,” says-
Paul Bremser, Wastewater Facility Superintendent “HSI was
not the lowest in price amongst the competitors but I knew
they stood behind their equipment. When I visited the opera-
tion in Houston, TX, I saw their Quality Center and that put my
worries to rest.”
Energy costs reduced by 20-40 %
Using a HT series blower can result in a 20-40 % reduction in
energy costs. Additional benefits include lower maintenance
costs, since there are no belts, gears or couplings and no lu-
brication, with the only scheduled maintenance being routine
inlet filter changes. The HT series is quiet, less than 80 dB(A)
and complying with OSHA standards. In addition, the HSI HT HSI High Speed Turbo blower HT-300 unit with the liquid-
series can operate in parallel with other types of blowers with cooled Vacon NXP drive. The liquid-cooled drive has only
a smaller footprint than traditional blowers. minimal power losses to the air, which reduces the need
for drive cabinet ventilation.
The HSI HT series are shipped as a pre-engineered working
system with integrated controls, Vacon variable frequency Photos: Courtesy of HSI
drive, filter inlet, and electrical disconnect to keep installa-
tion costs to a minimum.
Further energy savings are possible when utilizing the HT HSI is also a leading manufacturer of Multistage blowers that
blowers’ “plug and play” control system. This can be connect- use a standard induction motor. HSI’s choice of drive is the
ed directly to a dissolved oxygen probe via a 4-20 mA connec- air-cooled Vacon NXS drive. One item that separates Vacon
tion or via Ethernet to a plant SCADA for remote monitoring from other drive companies is their built-in AC line choke in
and operation, or HSI can add process control panels to au- the air-cooled Vacon NXS drives. There are many ways to re-
tomate the existing basin control valves, maintaining effluent duce the negative effects of harmonics generated back to the
quality while minimizing the total energy consumption of the line, and the standard AC choke on the air-cooled Vacon NXS
blowers. drive automatically reduces harmonics by an average 40 %.
It also helps with high voltage spikes or disturbances on the
line and protects the drive from possible damage.
Vacon liquid-cooled and air-cooled drives preferred
choices of HSI
“HSI offers a closed loop liquid cooling system or can use the
HSI has chosen the Vacon NXP liquid-cooled drive to vary discharge effluent if available; this makes a perfect marriage
the speed on their High Speed Turbo blower. There are many between the HSI High Speed Turbo blower and the liquid-
reasons for selecting the liquid-cooled Vacon NXP drive. It cooled Vacon NXP drive,” says Jim Pearsall, Vice President,
has the capability to control the speed on a special perma- HSI. “For our Multistage blowers, the air-cooled Vacon NXS
nent magnet 2 pole motor that can exceed speeds of 520 Hz or drive is the preferred choice.”
more than 30,000 RPM in this application. These PM motors
can sometimes run in open loop but may also require encod- “Two key advantages with the Vacon drive are continuity be-
ers and/or resolvers that are used to close the loop for more tween the programming for the liquid-cooled and the air-
precise speed control. Another major benefit from specifying cooled NXS drives and the possibility to use 10 kHz output
the Vacon liquid-cooled drive is the small footprint, typically carrier frequency that results in reduced audible noise,” says
33 % that of an air-cooled drive. This allows the drive to be in- Andrew Balberg, Vice President, Sales and Marketing, HSI.
stalled in the blower enclosure, maintaining the compact size
and low noise features of the High Speed Turbo blower. HSI is an ISO 9001-2008 certified manufacturer of high speed
turbo blowers, centrifugal blowers, exhausters and control sys-
tems with representatives worldwide. HSI offers blower equip-
ment performance ranges up to 25 PSI (1.7 bar) pressure or 18
inHg (457 mmHg) vacuum and flows from 100 CFM (3 m^3/hr) to
40,000 CFM (1130 m^3/hr). All engineering, manufacturing and
testing is located in Houston, Texas, USA.
Vacon, Inc.
1500 Nitterhouse Drive
RS000130A
Chambersburg, PA 17201, USA
Tel. +1 717-261-5000
Fax. +1 717-264-3115
www.vacon.com