capstone micro turbine & orc

Organic Rankine Cycle (ORC)Waste Heat Generator (WHG)

Technical Information providedby Greenvironment plc

confidential

1

Waste Heat Generator (WHG)

• Converts waste heat into electricity– Capable of using ‘low grade’ waste heat

•Waste Heat Generator (WHG)

2

Turbines

• Devices that converts fluidflow into work– Gas turbine

• Working fluid is combustionproducts and air

– Water turbine (hydro)• Working fluid is water

– Steam turbine• Rankine Cycle – water is boiled

to vapor before passing throughturbine

– Working fluid is water vapor(steam)

3

Rankine Cycle• Thermodynamic cycle which converts

heat into work– Working fluid is often steam

• Requires high temperatures to vaporize water• 80% of all power in the world is produced with this

technology

•Water

•CONDENSER

• Low Temperatureheat sources producelittle useable steam

• Inherit problem ishigh latent heat ofwater in liquid-vaporphase change

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Organic Rankine Cycle• For many (low temperature) waste heat applications, we

need a fluid that boils at a lower temperature than water– Historically, such fluids have been hydrocarbons - hence

the name Organic– Modern Working Fluids include: Propane / Pentane /

Toluene / HFC-R245fa• These Working Fluids allow use of Lower-Temperature

Heat Sources because the liquid-vapor phase change, orboiling point, occurs at a lower temperature than the water-steam phase change

Water R245fa

1 bar (0 psig) 100°C (212°F) 15,6°C (60°F)

19,6 bar (270 psig) 212°C (413°F) 121°C (250°F)

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Waste Heat Sources

• Waste heat is any source of otherwise unusedheat – that is why ‘fuel’ is free– Waste heat from MicroTurbine exhaust– Waste heat from industrial processes

• Process stacks from drying or heating processes– Heat from waste fuel

• Biomass or Biogas is burns to produce heat directly– Not waste heat

• A boiler creates heat for vaporization in a closed loopsystem – not free fuel

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The Complete System•Integrated

PowerModule

•EvaporativeCondenser•Evaporator

•HeatSource

•375F (190C)

•3 MBTU/H

•Generate

•125 kW •R245fa

•Pump

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How it Works - 1•Integrated

PowerModule

•Evaporativ

e Condenser

•Receiver

•Economizer

•Evaporator •Liquid

•85F (29C)

•230psig(16bar)

•Heat Source

•375F (190C)

•3 MBTU/H

•Generate

•125 kW

•Liquid

•85F (29C)

•26psig(1.8bar)

•R245fa

•Pump

The working fluid is in the receiver as a liquid at the condensing pressure and temperature. Itenters the pump where the working fluid’s pressure is raised to the evaporating pressure.

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How it Works - 2

•EvaporativeCondenser

•Receiver

•Economizer

•Evaporator

•Heat Source

•375F (190C)

•3 MBTU/H•Liquid

•118F(48C)

•220psig(15bar)

•R245fa

•Pump

The working fluid passes through a heat exchanger (Economizer) to take heat out of the gasleaving the Integrated Power Module. This improves system efficiency. The working fluid is now

a warmer, high pressure liquid.

•IntegratedPowerModule

•Generate

•125 kW

•Liquid

•85F (29C)

•230psig(16bar)

•Liquid

•85F (29C)

•26psig(1.8bar)

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How it Works - 3

•9


•Receiver

•Economizer

•Evaporator

•Vapor

•240F(115C)

•220psig(15bar)

•HeatSource

•375F(190C)

•3 MBTU/H

•R245fa

•Pump

The working fluid enters the Evaporator, where the working fluid is exposed to waste heat whichevaporates the fluid to a high pressure vapor.


•Generate

•125 kW

•Liquid

•118F(48C)

•220psig(15bar)

•Liquid

•85F (29C)

•230psig(16bar)

•Liquid

•85F (29C)

•26psig(1.8bar)


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How it Works - 4


•Receiver

•Economizer

•Evaporator

•Heat Source

•375F (190C)

•3 MBTU/H

•Vapor

•145F(63C)

•26psig(1.8bar)

•R245fa

•Pump

The working fluid (now a vapor) enters the turbine of the IPM. The working fluid’s pressure dropsacross the turbine to the condensing pressure, spinning the turbine (which is connected to the

generator) in the process. The driving force is the pressure difference across the turbine.

•Generate

•125 kW

•Vapor

•240F(115C)

•220psig(15bar)

•Liquid

•118F(48C)

•220psig(15bar)

•Liquid

•85F (29C)

•230psig(16bar)

•Liquid

•85F (29C)

•26psig(1.8bar)

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How it Works - 5

•11


•Receiver

•Economizer

•Evaporator

•Heat Source

•375F (190C)

•3 MBTU/H

•R245fa

•Vapor

•85F(29C)

•26psig(1.8bar)

•Pump

The working fluid still has an enormous amount of heat, some of which is transferred to thepumped liquid in the economizer. This helps in two ways: 1) this heat would have otherwise

been extracted in the condenser and; 2) there is less heat required at the evaporator due to theliquid being pre-warmed.

•Vapor

•145F(63C)

•26psig(1.8bar)

•Vapor

•240F(115C)

•220psig(15bar)

•Liquid

•118F(48C)

•220psig(15bar)

•Liquid

•85F (29C)

•230psig(16bar)

•Liquid

•85F (29C)

•26psig(1.8bar)

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How it Works - 6


•Receiver

•Economizer

•Evaporator

•HeatSource

•375F(190C)

•3 MBTU/H

•AmbientAir 75F(24C)

•Wet Bulb

•R245fa•Vapor

•85F (29C)

•26psig(1.8bar)

•Pump

The working fluid (still a vapor) then flows to the condenser where heat is extracted and theworking fluid condenses to a liquid.

•Vapor

•85F(29C)

•26psig(1.8bar)

•Vapor

•145F(63C)

•26psig(1.8bar)

•Vapor

•240F(115C)

•220psig(15bar)

•Liquid

•118F(48C)

•220psig(15bar)

•Liquid

•85F (29C)

•230psig(16bar)

•Liquid

•85F (29C)

•26psig(1.8bar)

13

How it Works - 7


•Receiver

•Economizer

•Evaporator

•R245fa

•Pump

The low pressure, liquid working fluid drains back to the receiver and is ready to be pumped tohigh pressure and flow towards the integrated power module.

•Heat Source

•375F (190C)

•3 MBTU/H

•AmbientAir 75F(24C)

•Wet Bulb

•Vapor

•85F (29C)

•26psig(1.8bar)

•Vapor

•85F(29C)

•26psig(1.8bar)

•Vapor

•145F(63C)

•26psig(1.8bar)

•Vapor

•240F(115C)

•220psig(15bar)

•Liquid

•118F(48C)

•220psig(15bar)

•Liquid

•85F (29C)

•230psig(16bar)

•Liquid

•85F (29C)

•26psig(1.8bar)

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Applications

• Turbines Exhaust– Waste heat from exhaust

• Industrial Stack Gas– Refineries– Incinerators– Drying processes

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Applications

• Geothermal– Water or Steam

• Solar Thermal– After steam process– Indirect evap source

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The ORC Power Skid• Capstone supplies the ORC ‘Power Skid’

– Includes electronics, receiver, economizer, power module andvarious pumps

– Needs external evaporator and condenser

Power Skid Fluid Connections

•Warm Liquid toEvaporator

•Cool Liquid fromCondenser

•Hot Vapor fromEvaporator

•Warm Vapor toCondenser

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Power Skid Components

•Receiver

•Pump

•FieldConnections


•Power

•Electronics

•ProgrammableLogic Controller

(PLC) & MagneticBearing Controller

(MBC)

•VFD for Pump

•Separator •Inlet ControlValve

•BypassValve•Economizer

•SeparatorDrain Valve

•SlamValve

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Power Skid Specs

• Turbine Expander and Generator– Hermetically sealed power module – no leaks– Magnetic Bearings – no lubricants– 26,500 rpm – no vibration

• Power electronics – 125 kW– Grid Connect only– 380-480V, 3 phase, 3 wire 50/60 Hz

• Working fluid HFC-R245fa• Dry weight 7,000 lbs• 46” w x 112” l x 79.5” h

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Evaporator• Transfers waste heat energy to refrigerant,

resulting in vaporization– Direct, heat transfers directly from the waste heat source

to the working fluid• Likely choice for a Microturbine application where waste

temperatures are low and exhaust stream is clean• Heat source needs to be near ORC

– Indirect, thermal transfer medium is used between theheat source and the working fluid (e.g. thermal oil, hotwater, steam)

• Requires more ancillary equipment• Less efficient overall• Good fit if heat source is far from ORC

21

Condenser• Rejects latent heat of working fluid, resulting in

condensation– Direct – The working fluid passes through a heat

exchanger that rejects heat directly to the environment.– Indirect – A medium such as water is passed through a

heat exchanger and takes the rejected heat out of theworking fluid. The medium then transfers the heatsomewhere else.

– Cooling towers, air cooled condenser (Dry Cooler),ground water, evaporative condenser

• Cooling towers (if already existing) and direct evaporativecondensers are likely the best match for MicroTurbineapplications

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Installation Considerations• Evaporator & Condenser must be within 50ft of the

ORC power skid– Minimize refrigerant run length

• Minimize heat loss / absorption• Minimize amount of R245fa used

• Condenser must be elevated (flow to receiver)• Qualified technician required to handle R245fa• Internal cleanliness (of R245fa loop) important

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Complete Installation

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Heating, Cooling, Power

• Cycle effectiveness is determined by theheat source and condensing source– Determine total heat and temperature available– Determine total cooling available

• Power available is determined by multiplyingthe heat available by the cycle effectiveness– More heat available => less cooling required– Less heat available => more cooling required

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Available Power Output• More heat is

required for agiven powerproduction ascondensingtemp increases.

• Size heatsource andcondenser forambientconditions.

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ORC with MicroTurbines• Typical MicroTurbine implementation

– 6 to 8 Capstone C65 MicroTurbines– One ORC WHG Power Skid– One direct MT exhaust to refrigerant heat

exchanger– One direct evaporative cooling tower or

piggyback on existing cooling tower.

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Free Electricity?

• Or, how to build a ORC WHG valueproposition– System uses low grade heat that is usually

wasted – no other good use– Increase overall efficiency of systems– Consumes no additional fuel– Produces no additional emissions– Wasted energy into electric power may

• Reduce demand charges• Capture carbon credits• Qualify for renewable energy incentives

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Calculating New Efficiency

• Using waste heat to generate electric powerincreases overall system efficiency– Low grade waste heat is used, so assume it can

not be used for any other purpose– Example, 6 Capstone C65s

• Produce 390kW at 29% Electric Eff• A 125kW ORC WHG is added• 515kW is produced, using no added fuel• new efficiency is

– (New power/old power)*old Efficiency = 38%

• The ORC increases electric efficiency to over 38%

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Case Study• Biomass boiler test site in the south east USA.

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Case Study Payback• Free fuel and low Maintenance Cost provide

payback

Annual Run Hours 8,400

Net Electrical Output 107kWe

Annual Production 8,400 x 107 = 898,800 kWh

Gross Revenue 898,800 x $0.18 = $161,784

Maintenance Cost 898,800 x $0.0075 = $6,741

Net Annual Revenue $155,043

Cost of Project $298,000

Simple Payback < 2 years

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Technology Advantages• Very similar to those of Capstone MicroTurbines

High Speed Generator Increased Efficiency, Reliability, no gear box

Magne<c BearingsIncreased Efficiency, Reliability, Reducedlosses

Power Electronics Efficient variable speed opera<on

No lubrica<on or lubrica<on systemIncreased Reliability, Reduced parasi<c losses,No contamina<on of process fluid

No coupling Increased reliability, fewer components

Variable speed opera<on Op<mized cycle efficiency opera<ng point

Herme<cally sealed Higher reliability, fewer wear components

Single moving part Increased reliability

Modular DesignSimple Integra<on into system (like standardpiping)

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