Large Bubble Vertical Mixing – Energy Savings and Performance Enhancement

LARGE BUBBLE VERTICAL MIXING

Energy Savings and Performance Enhancement

LARRY L. BELL

V.P. SALES PULSED HYDRAULICS INC.

Aeration is 54% of the Total Power Consumed

Aeration 54%Return SludgePumping 0.46%

Gravity Thickening 0.06%

AnaerobicDigestion 14.24%

Belt Press 3.91%

ChlorinationLighting &Buildings 8.14%

WastewaterPumping 14.26%

Screens 0.02%

Grit 1.26%

Clarifiers 3.15%

Electrical Usage in WWTPs

AERATION BASIN MIXING

• PERHAPS THE MOST OVERLOOKED ASPECT OF PROCESS TREATMENT !

• IF YOU ASK 10 PEOPLE WHAT IT IS, YOU WILL PROBABLY GET 10 DIFFERENT ANSWERS !

HORIZONTAL MIXING

• ANY MIXING SYSTEM THAT MOVES THE LIQUID IN A HORIZONTAL PLANE IS NOT REALLY MIXING……IT IS STIRRING !

• SOLIDS TEND TO ACCUMULATE ON THE BOTTOM, IN THE CORNERS AND IN THE MIDDLE OF THE STIRRING VORTEX !

HORIZONTAL MIXERS STIR … NOT MIX!

VERTICAL MIXING

• MIXING SYSTEMS THAT MOVE THE LIQUID IN A VERTICAL PLANE TEND TO INVOLVE THE ENTIRE VOLUME OF THE TANK !

• LIFTING SOLIDS VERTICALLY USES THE FORCES OF BUOYANCY AND GRAVITY TO DISPERSE TANK CONTENTS MORE EVENLY WITHIN THE TANK !

LARGE BUBBLE VERTICAL MIXERS USE BUOYANCY AND GRAVITY TO EVENLY

DISBURSE SOLIDS

TYPES OF VERTICAL MIXERS

• 1. MECHANICAL

• 2. AIR

A. Continuous Flow

i. Fine Bubble

ii. Course Bubble

B. Pulsed

i. LARGE BUBBLE

ii. Small Bubble

MECHANICAL VERTICAL MIXER

1. MOVING PARTS IN THE TANK NEED MAINTENANCE

2. FLUID IS PULLED DOWN THE MIDDLE OF A MIXING ZONE

AND UP THE OUTSIDE THE MIXING ZONE EDGES.

3. ALL ENERGY USED HAS TO BE SUPPLIED EXTERNALLY.

Aeration Enhancement

Improving Nutrient Removal and Energy Efficiency

The ultimate goal:

A. Lower Energy Costs

B. Improved Treatment Efficiencies

These can be achieved via an integrated solution:

1. Variable-speed high-efficiency blowers.

2. High efficiency diffusers.

3. Large bubble, vertical mixing system.

4. On-line instrumentation (automate the

blowers and mixing system)

TANK VOLUME RECOVERY BY LARGE BUBBLE MIXING

SEOUL, SOUTH KOREA

• One Bubble Forming Plate per 30 foot square zone = 1-2 HP

• Achieved complete mixing in each zone (< 2% TSS variation from top to bottom)

• D.O. increased allowing blower scfm to be lowered

• BOD / NH3 removal efficiency improved allowing increased loadings

• Final pilot plant paper due out in February 2013

AERATION ENHANCEMENT & ANOXIC MIXING

Innovative Equalization Tank and Mixing System Eliminates SSOs, Improves Plant Performance,

and Saves Money

Project: Shelby County Lake Loramie WWTP Wet Weather Flow Equalization Improvements

Presented by: Jeremy M. Cook, PE

URS Corporation – Columbus, Ohio

Mixing Systems Evaluated • Coarse Bubble Diffusers Submersible Propeller Mixers

Submersible Jet Pumps

Pulsed Air System

Submersible Propellor and Jet Pumps

Simple Installation and No Blower Building

Large Horsepower Requirements (approx. 120 HP) created by large tank diameter (greater Thrust)

Capital Costs: $150,000

Electrical Cost: 120 HP @ $0.08/kwh for 90 days, 24 hr/day = $15,500

Coarse Bubble Mixing System

2,500 scfm Centrifugal Blower (approx. 80 HP)

200 SS Wide Band Diffusers

Large tank diameter would have required a lot of SS pipe and diffusers

Need a Blower Building or Enclosure

Estimated Capital Cost: $300,000

Electrical Cost: 80 HP @ $0.08/kwh for 90 days, 24 hr/day = $10,400

Small Precast Building to house 20 HP Compressor, 240 gal. Receiver, Solenoid Valves & PLC Controller.

1”SS Piping and 40 Bubble Forming Plates

Capital Costs: $100,000 (with building); saving $50,000

Electrical Cost: 20 HP @ $0.08/kwh for 90 days, 24 hr/day = $2,600; saving $12,900 /yr

Manufacturer: Pulsed Hydraulics, Inc. (PHI)

Lake Loramie (OH) Sanitary District

EQ Tank

45 FOOT DIAMETER SLUDGE

STORAGE TANK

POWER COST FORMULA

Cost = (bhp) x (0.746) x (hours) x (power

rate) / motor efficiency

Where: bhp (brake horsepower

power rate ($ per kilowatt hour)

Hours (operating hours)

motor efficiency (%)

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

EXISTING BLOWERS AND COURSE AIR

DIFFUSERS :

75 HP operating 24 hours / 7 days per

week

Power Rate is $0.07 and Motor Efficiency

is estimated at 93%

(75) x (0.746) x (24) x ($0.07) / 0.93 =

$101.07 / Day ($36,890.90 per year)

LARGE BUBBLE VERTICAL MIXING

SYSTEM:

10 HP operating 24 hours / 7 days per

week

Power Rate is $0.07 and Motor Efficiency

System pulls 7 kw when operating on load

(not 7.46 kw if calculated 10 x 0.746 as in

above formula).

(7 kw) x (24) x ($0.07) / 0.93 = $12.65 /

Day ($4,617.25 per year)

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

ANNUAL ENERGY SAVINGS =

$32,273.65

The above calculation for the large bubble

vertical mixing system was computed on

the basis of the mixing system operating

on load 24 hours per day / 7 days per week

utilizing the full 10 HP capacity of the

compressor. Actual operating HP has

been estimated to be 4.5 to 6 HP.

What are the mixing applications?

• Aeration / anoxic basins in WWTPs

• Sludge

• Polymer & Hypochlorite Chemical Storage Tanks

• Lift Station Wet Wells

• Flow Equalization Basins

• Elevated & Ground Level Water Storage Tanks

• Petroleum Storage Tanks (Vented)

• Foods and Beverages (Wine – Whiskey)

• Any Liquid In A Vented Vessel or Tank

OTHER APPLICATIONS & VIDEOS

•GO TO WWW.PHIWATER.COM

•SELECT THE APPLICATION TAB

•SELECT THE APPLICATION OF INTEREST

•WATCH A VIDEO OF MIXING OCCUR OR DOWNLOAD THE APPLICATION LITERATURE

Duration

Pulses Per

Minute

CFM

Required Input kW

CFM

Per Pulse

.3 seconds 2 times 3.4 CFM 0.97 kW 1.7 CFM

.4 seconds 2 times 4.9 CFM 1.42 kW 2.5 CFM

.5 seconds 2 times 5.5 CFM 1.57 kW 2.8 CFM

How much air is used ?