Fishbeck, Thompson, Carr & Huber, Inc.

Application of High-Speed Turbocompressors at Municipal WWTPs in Michigan

Jim Flamming, P.E. , Senior Process Engineer,Fishbeck, Thompson, Carr & Huber, Inc.

Aeration Blowers

Aeration consumes 40-70% of energy used in activated sludge plants (WEF MOP OM-9)

For supplying diffused aeration grids, 2 types: Positive Displacement

Approx. 60% efficient Typically smaller (<100 hp) Output varies with speed,

not pressure Factory or OEM packages available Widely applied, low capital costs

Aeration Blowers

Multistage Centrifugal: Approx. 65-75% efficient Wide range of sizes, typ. >50 hp Output varies with pressure Widely applied for over 100 yrs. Can be more expensive initially

than positive displacement PD and multistage blowers are the workhorses

of the industry.

But Times Are Changing!

With renewed emphasis on energy efficiency, new styles of blowers are starting to be applied.

High speed turbocompressors offer several potential advantages over traditional blowers: Higher efficiencies Lower maintenance costs Variable output Quiet operation

High Speed Turbocompressors

Operate at very high speeds:25,000 to 45,000 rpm

No contact bearing surface: magnetic or airfoil bearings

No contact = no friction = no wear parts Oil free operation; no lubrication required

or bearings to service Very low maintenance

High Speed Turbocompressors

10-20% improvement in efficiency Operate on VFDs; maintaining best efficiency at

turndowns of up to 50% of max output No contact – very low vibrations – low noise

(<70 dB at operating speed) Factory supplied package units with controls Typically small footprints

High Speed Turbocompressors

Different styles from different manufacturers Magnetic Bearings – ABS/HST, Hoffman

Revolution, Atlas Copco ZB-VSD; Spencer AyrJet Air Foil Bearings – HIS HT; K-Turbo; APG-Neuros;

Turblex Magnetic bearings prevent any contact during

operation, but typically cost more upfront Most are direct drive units; Turblex also provides

a separately geared unit with additional control capability

ABS/HST

Of the direct drive units, so far ABS/HST has the most installations in the U.S. at municipal WWTPs (61 units at 21 WWTPs, and 1300 units worldwide)

Built in Sweden Only one with direct drive installations so far in

Michigan, at three sites, which we will review as case studies

ABS/HST

Five models 93-536 HP 600-10,400 scfm 5.5 – 18.2 psig

discharge pressure

ABS/HST

Fishbeck, Thompson, Carr & Huber, Inc.

Case StudiesMichigan WWTPs

Marquette WWTP

Replaced RBCs with three plug

flow 500,000-gallon nitr. basins;

plus one 500,000-gallon WAS tank 1 50-hp and 1 75-hp blower to

three 200-hp turbocompressors

(ABS HST SP6000-1-L-5) each

4,337 scfm at 8 psig Start up July 2008

Coldwater WWTP

Trickling filter-solids

contact plant NH3 violations, May 2007 Installed new IFAS, which

required added aeration

(presented in Session 1) Existing plant had two

75-hp, 900-scfm blowers

Coldwater WWTP

Installed two 93-hp ABS/HST

S2500-2-A-5; each 1,257

scfm at 8 psig Placed in new building;

existing blowers remain as

backup units City doesn’t have historical

flow and hp draw data for

blowers; difficult to compare

Reed City WWTP

Three basin SBR plant Industrial/municipal WW Utilized three 150-hp PD

blowers which had

HIGH rates of failure Replaced units with four

111-hp HST S2500-1-H-5;each 1,969-scfm at 8 psig innew blower building

Reed City WWTP

Reed City WWTP

After installation, plant measured output: Old blowers rated for 3,000 scfm with

two blowers running New HSTs – 3,600

scfm at 80 hp DO’s higher in SBRs

Low noise Virtually no vibration Still in start-up;

addressing electrical

issues at site

Some Things To Consider…

HSTs may not be suitable for every plant Relatively high initial capital costs; need to do

a life cycle cost analysis; magnetic vs. air-foil Not cost-effective at lower HP requirements Would not want to parallel with PD blowers Sophisticated electronics, need to review

existing electrical service and power quality Faults happen during start-up

Conclusions

The world of wastewater treatment is changing New PLC-based controls open up the

possibility for new kinds of technologies Offer better efficiencies and less maintenance While not for every application, HSTs offer

some intriguing advantages that are worth consideration .

Fishbeck, Thompson, Carr & Huber, Inc.

Any Questions?

Thank you