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POTW Energy Use and Waste to Energy- Solution to Environmental Challenges

Chris Tippery, Symbiont

Energy Savings Made Easy | 2017 Business Symposium

AERATION & ENERGY

» Utility costs are expected to increase in the future

» U.S. WTPs & WWTPs account for roughly 100 billion kWh

annually (Electric Power Research Institute)

» Aeration system power requirements are often 40% to

60% of an activated sludge plant’s total energy demand

» Electricity is produced from mostly non-renewable

resources


Example POTW – 5.5 MGD

» Aeration energy cost is approximately $260,000/yr at

$0.05/kWh

» Normalized aeration energy use:

• 1,710 kWh/MG

• 538 kWh/1,000 lb BOD (raw influent)


Aeration System Review

Basins (4) Buried Concrete Tanks, Each with Anoxic and Oxic

Zones

Diffuser Type Fine Bubble Ceramic Diffusers

Blowers

(3) 600 HP and (2) 400 HP Multistage Centrifugal

Blowers

Installed in 1989

Controls

Soft Starts, DO Control of Air Flow, Surge Protection,

Time Delays

Installed in 1989


DESIGN FOR ENERGY REDUCTION

o Air flow rate should be varied according to wastewater

oxygen demand

o Dissolved oxygen measurements used to vary air flow in

real time

o Blower surge control considerations



» Potential aeration flow control methods:

• Flow blow-off

• Inlet throttling

• Adjustable discharge diffuser

• Variable speed drive

• Parallel operation of multiple units

Best choice



» The two 400 HP blowers provide sufficient air flow (max.

11,260 cfm) for normal operations

» Control Modifications

Set 400 HP blowers to Lead and Lag 1

Set 600 HP blowers to Lag 2, Lag 3 & Backup



• Two 18 pulse, IEEE 519, 460V, 400HP VFD units


AERATION SYSTEM ELECTRICAL USAGE IMPACT

Before VFD Upgrade After VFD Upgrade Energy Reduction

45.2% of facility 39.7% of facility 12.2%

(percent change)

8,570 kWh/d 7,300 kWh/d 14.8%

1,710 kWh/MG 1,569 kWh/MG 8.2%

538 kWh/1000lb BOD 473 kWh/1000lb BOD 12.1%


FINANCIAL IMPACT REVIEW

o Construction cost of approximately $115,000

o Annual utility savings of $14,800 at $.05/kWh

o Received a State Energy grant of $46,500

o Payback Period:

o 4.6 years with grant

o 7.8 years without grant

o Grant required application and justification submittals


Food Production Creates Waste

Examples of food processing by-products

Peels

Shells

Float

Whey

Oils

Paunch

Spent Yeast

Non-Saleable Product


Issues With Waste Disposal


Characteristics of Optimal Waste Feedstock

» Easily biodegradable

» COD > 10,000 mg/L (higher the better)

» No heavy metals

» Low levels of toxic cleaning compounds

• Peracetic acid

• Quaternary ammonium

» Reasonable levels of N, P, and Chlorides


Waste-to-Energy: The Process


General Biogas Properties

50-70% CH4 / 30-50% CO2 / saturated with water / traces

of H2S and other gases

Heating value (dry) = 500 to 800 BTU/cf


Surge

Tank

Engine

Relief

Valve

Exhaust

Heat

Recovery

Unit

Mixing

Valve

External

Radiator

Circulating

Pump

Heat

Exchanger

Process

Bypass Valve

Loop Warm up

Biogas Use - IC ENGINE HEAT RECOVERY SYSTEM


Green Whey Energy

Turtle Lake, Wisconsin

Challenge: » Develop a regional, sustainable process to dispose of

cheese making wastes that were overloading local

POTW

» Reduce/eliminate land application

Solution: » Regional processing center for waste using anaerobic

digestion


Green Whey Energy

Turtle Lake, Wisconsin

Results: » Converts cheese making waste into electricity

» Uses Upflow Anaerobic Contact process

» Processes about 300,000 gpd of waste with average

COD of 35,000 mg/L

» Produces 1.25 million cubic feet per day biogas

» Generates 3.2 MW of electricity using engines

» Heat recovery

» Discharges pretreated effluent without overloading

POTW


Forest County Potawatomi Community

Milwaukee, Wisconsin

Challenge: » In accordance with tribal culture and tradition, develop

a means to protect and enhance the environment and

become energy independent

Solution: » Construct a high strength waste processing center using

anaerobic digestion to create renewable energy


Forest County Potawatomi Community

Milwaukee, Wisconsin

Results:

» Flexible to receive various industrial high

strength wastes

» Anaerobic Membrane Bioreactor process

» Processes 120,000 gpd with COD of 95,000 mg/L

» Produces 778,000 cubic feet per day biogas

» Generates 2 MW of electricity plus heat

recovery for buildings, casino, and process

» Discharge to city sewer

Questions?

Chris Tippery Symbiont

Variable Refrigerant Flow (VRF)

Christopher Swallow – Thermal Mechanics, INC


Development of VRF

» 1973 – Global oil crises

» 1979 – New energy efficiency laws passes in Japan

» 1980 – Chiller design engineers challenged with making a higher

efficiency chiller

» 1982 – The worlds first VRF System is launched

» MOVE REFRIGERANT THROUGH PIPE NETWORK IN LIEU OF WATER

Water

2.6 watts/lb

25 watts/lb

Refrigerant

Air

0.14 watts/lb

VAV VWV VRF


Reduced Space Requirements

7 Ton Ductwork

28 Tons of Refrigerant Pipes


VRF in the Global Market

~16%

~12%

31% 53%

45%

70%

~53%

33%

54%

~40%

23%


VRF Concept

Think of a VRF system as a chiller / boiler that circulates refrigerant to each zone instead of water

A heat pump system is equivalent to a 2 pipe chiller

Major benefit is smaller heat/cool changeover zones due to the modular build up

A heat recovery system is equivalent to a 4 pipe chiller system

6 Ton

6 Ton

Heat recovery

Cooling Cooling Heating

12 Ton

Heat Pump


Parts and Pieces


Heat Pump


Heat Recovery


How Does the VRV Inverter Control the System

52~210Hz

Applied frequency

37 Applied Capacity Steps

Condenser Control

COOL Operation

HEAT Operation

14%

100%

Inverter control Adjusts

compressor speed (capacity) up or down to

correct deviation from the target pressure

values (system load)

Sets Target low & high pressure

values at the Condenser

Sets the Target evap. & cond.

Temps in the indoor Fan Coils

Local Remote Controllers initiate a

system Thermo-ON with a 1°

deviation from set point

Local Remote Controllers initiate a

system Thermo-OFF when all set

points are reached

Control System

Detects the system operating suction

pressure at Condenser once every 20

seconds

Detects the system operating high

pressure at Condenser once every 20

seconds


Average VRV System Performance

0.02.04.06.08.0

10.012.014.016.018.020.022.024.026.0

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

EER

Load

Partial Load Performance (VRV)

75%

595

340

680

340

170

425

510

255

85

System Operation

Hours

75% of total operation

hours- less than 70% of full load

Questions?

Chris Swallow Thermal Mechanics

Combined Heat and Power

Charlie Mayer Clarke Energy


Combined heat and power (CHP) is a high

efficiency technology for generating power

in the form of electricity and heat, on site

and from a single fuel source

Recip Engine-Generator Sets in CHP


Why CHP?

Fuel

(100%)

Electricity for

transmission

(35%)

Generation/heat

losses (65%)

Conventional

Power Plant

Gas-fuelled

CHP plant

90%

Efficiency

Generation/heat losses

(10%)

Fuel

(100%)

Electricity

(45%)

Useful Heat

(45%)

Transmission

Losses (1.5%)

Supplied

electricity

(efficiency)

33.5%


CHP solutions are applicable in a wide variety of

energy-intensive facilities

Combined heat and

power plant

Industrial manufacturers,

institutions, commercial

buildings

Residential communities, municipalities

• Industrial manufacturers - chemical,

refining, pulp and paper, food

processing, glass manufacturing,

cement, steel mills

• Institutions - colleges and universities,

hospitals, prisons, military bases

• Commercial buildings - hotels and

casinos, airports, high-tech

campuses, large office buildings,

nursing homes

• Municipal - district heating systems,

wastewater treatment facilities

• Residential - multi-family housing,

planned communities


US CHP Installation Data


Combined heat and power


Combined heat power and cooling


Combined heat, power and CO2 recovery

Combined heat, power and CO2 recovery


Gas Engine Module Basics


Fuel Flexibility

Landfill gas Sewage gas

Associated

petroleum gas

Special gases

Biogas

Greenhouse

applications

Cogeneration

(Natural gas)

Coal mine gas

Island mode


Flexible Delivery Model

» Genset • Gas engine

• Generator

• Base frame

• Fuel gas train

• Genset control panel

• Design and Documentation

• Options



» Power module • Item 1 plus

• Ventilation system

• Acoustic/weatherproof enclosure

• Silencer

• Radiators

• Fire and gas detection

• Electrical and I&C

• Further options

• Co/tri-generation



» Power plant • Item 2 plus

• Civil work

• Gas conditioning plant

• Lube oil system

• HV/LV switch room, control room, electrical sub-stations , metering

and reticulation

• Black-start diesel generators

• Storage / workshops

• Further options


CHP is an application…not a product

Design must accommodate system complexity

• Balance fluctuations in seasonal thermal load demand

• Complete understanding of application requirements dictates plant size

• Systems integration of components and configuration to drive resiliency, flexible and reliable operation

• Optimize around financial returns and policy incentives


End to End Service

Contact

Clarke Energy USA Inc.

2100 Pewaukee Road,

Waukesha, WI 53188

Tel: +1 (262) 565 5020

www.clarke-energy.com

Questions?

Charlie Mayer-Clarke Energy

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