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

Presented by Grant Terzer and Marc Rouse

2010 Regional Distributor Review & Conference

Americas

June 14-17, 2010

2

Waste Heat Generator (WHG)• Converts waste heat into electricity

– Capable of using ‘low grade’ waste heat

• Waste Heat Generator (WHG)

3

Turbines• Devices that convert fluid

flow into work– Gas turbine

• Working fluid is combustion products and air

– Water turbine (hydro)• Working fluid is water

– Steam turbine• Rankine Cycle – water is boiled

to vapor before passing through turbine

– Working fluid is water vapor (steam)

4

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 Temperature

heat sources produce

little useable steam

• Inherent problem is

high latent heat of

water in liquid-vapor

phase change

5

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, or boiling 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)

6

Waste Heat Sources

• Waste heat is any source of otherwise unused heat – 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 burned to produce heat directly

– Not waste heat• A boiler creates heat for vaporization in a closed loop

system – not free fuel

7

The Complete System• Integrated

Power

Module

• Evaporati

ve

Condense

r

• Evaporat

or

• Heat

Source

• 375F

(190C)

• 3 MBTU/H

• Genera

te

• 125 kW

• R245fa

• Pump

8

How it Works - 1• Integrate

d Power

Module

• Evaporat

ive

Condens

er• Receiver

• Economi

zer

• Evaporat

or

• Liquid

• 85F

(29C)

• 230psig

(16bar)

• Heat

Source

• 375F

(190C)

• 3 MBTU/H

• Generat

e

• 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. It enters the pump where the working fluid’s pressure is raised to the evaporating pressure.

9

How it Works - 2

• Evaporati

ve

Condense

r• Receiver

• Economi

zer

• Evaporat

or

• 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 gas leaving the Integrated Power Module. This improves system efficiency. The working fluid is now

a warmer, high pressure liquid.

• Integrate

d Power

Module

• Generat

e

• 125 kW

• Liquid

• 85F

(29C)

• 230psig

(16bar)

• Liquid

• 85F

(29C)

• 26psig

(1.8bar)

10

How it Works - 3

• Evaporati

ve

Condense

r• Receiver

• Economiz

er

• Evaporat

or

• Vapor

• 240F

(115C)

• 220psig

(15bar)

• Heat

Source

• 375F

(190C)

• 3

MBTU/H

• R245fa

• Pump

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

• Integrate

d Power

Module

• Generat

e

• 125 kW

• Liquid

• 118F

(48C)

• 220psig

(15bar)

• Liquid

• 85F

(29C)

• 230psig

(16bar)

• Liquid

• 85F

(29C)

• 26psig

(1.8bar)

• Integrate

d Power

Module

11

How it Works - 4

• Evaporati

ve

Condense

r• Receiver

• Economiz

er

• Evaporat

or

• 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 drops across 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.

• Generat

e

• 125 kW

• Vapor

• 240F

(115C)

• 220psig

(15bar)

• Liquid

• 118F

(48C)

• 220psig

(15bar)

• Liquid

• 85F

(29C)

• 230psig

(16bar)

• Liquid

• 85F

(29C)

• 26psig

(1.8bar)

12

How it Works - 5

• Evaporati

ve

Condense

r• Receiver

• Economiz

er

• Evaporat

or

• 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 the pumped 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 the liquid 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)

13

How it Works - 6

• Evaporati

ve

Condense

r• Receiver

• Economiz

er

• Evaporat

or

• Heat

Source

• 375F

(190C)

• 3

MBTU/H

• Ambient

Air 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 the working 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)

14

How it Works - 7

• Evaporati

ve

Condense

r• Receiver

• Economiz

er

• Evaporat

or

• R245fa

• Pump

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

• Heat

Source

• 375F

(190C)

• 3 MBTU/H

• Ambient

Air 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)

15

Applications• Turbines Exhaust

– Waste heat from exhaust

• Industrial Stack Gas– Refineries– Incinerators– Drying processes

16

Applications• Geothermal

– Water or Steam

• Solar Thermal– After steam process– Indirect evap source

17

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

– Includes electronics, receiver, economizer, power module and various pumps

– Needs external evaporator and condenser

Power Skid Fluid Connections

• Warm Liquid to

Evaporator

• Cool Liquid from

Condenser

• Hot Vapor from

Evaporator

• Warm Vapor to

Condenser

19

Power Skid Components

• Receiver

• Pump

• Field

Connection

s

• Integrated

Power

Module

• Power

• Electronics

• Programmable

Logic Controller

(PLC) &

Magnetic

Bearing

Controller

(MBC)

• VFD for Pump

• Separator • Inlet

Control

Valve

• Bypass

Valve• Economiz

er• Separator

Drain

Valve

• Slam

Valve

20

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

21

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 the heat source and the working fluid (e.g. thermal oil, hot water, steam)• Requires more ancillary equipment• Less efficient overall• Good fit if heat source is far from ORC

22

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 the working fluid. The medium then transfers the heat somewhere else.

– Cooling towers, air cooled condenser (Dry Cooler), ground water, evaporative condenser• Cooling towers (if already existing) and direct evaporative

condensers are likely the best match for MicroTurbine applications

23

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

24

Complete Installation

25

Heating, Cooling, Power• Cycle effectiveness is determined by the

heat source and condensing source– Determine total heat and temperature available– Determine total cooling available

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

26

Available Power Output• More heat is

required for a given power production as condensing temp increases.

• Size heat source and condenser for ambient conditions.

• 125kW nominal is at generator terminals (inverter loss approx. 8 kW)

27

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.

28

Free Electricity?• Or, how to build a ORC WHG value

proposition– 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

29

Calculating New Efficiency• Using waste heat to generate electric power

increases 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

– Assume net output is 110kW (due to system losses, heat source and condensing source.

• 500kW is produced, using no added fuel• new efficiency is

– (New power/old power)*old Efficiency = 37%• The ORC increases electric efficiency to over 37%

30

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

31

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

32

Technology Advantages• Very similar to those of Capstone MicroTurbines

High Speed Generator Increased Efficiency, Reliability, no gear box

Magnetic Bearings Increased Efficiency, Reliability, Reduced losses

Power Electronics Efficient variable speed operation

No lubrication or lubrication system Increased Reliability, Reduced parasitic losses, No contamination of process fluid

No coupling Increased reliability, fewer components

Variable speed operation Optimized cycle efficiency operating point

Hermetically sealed Higher reliability, fewer wear components

Single moving part Increased reliability

Modular Design Simple Integration into system (like standard piping)

33

For More Information• Contact Capstone Applications or Sales

Question & Answer