The Fundamentals of Combined Heat and Power
(CHP)
Modules 1 & 2
Presented to:
Wilbur Wright College
November 5th, 2009
Presented By:
John Cuttica
University of Illinois at Chicago
Midwest CHP Application Center
1
Topics to be Covered
ƒ Module #1: DG/CHP Concept Characteristics
ƒ Module #2: CHP Technology Building Blocks
ƒ Module #3: CHP Example Market Applications
ƒ Module #4: Preliminary Site Analysis
2
Conventional Energy System
70 units thermal
rejected / lost
100 units
fuel input
Central
Station
30 units electric
• Customer purchases power
from grid (central station)
• Power plant economy of scale
• 100 units input = 30 units of power
• Remainder of energy (70%) lost (heat)
3
Conventional Energy System
70 units thermal
rejected / lost
100 units
fuel input
Central
Station
30 units electric
20 units thermal
rejected / lost
100 units
fuel input
Boiler
80 units thermal
• Customer purchases power
from grid (central station)
• Power plant economy of scale
• 100 units input = 30 units of power
• Remainder of energy (70%) lost (heat)
• On-site generation of steam/hot
water/hot air (boilers/furnaces)
• 100 units input = 60 to 80 units of heat
4
Conventional Energy System
70 units thermal
rejected / lost
100 units
fuel input
Central
Station
30 units electric
20 units thermal
rejected / lost
100 units
fuel input
Boiler
80 units thermal
• Customer purchases power
from grid (central station)
• Power plant economy of scale
• 100 units input = 30 units of power
• Remainder of energy lost (heat)
• On-site generation of steam/hot
water (boilers/furnaces)
• 100 units input = 60 to 80 units of heat
• Typical grid power + onsite heat
• Efficiency depends on heat/power ratio
• 40% to 55% combined efficiency is
common
5
Distributed Generation
DG is …
DG Technologies …..
• An Electric Generator
• Solar Photovoltaic
• Located At a Substation or
Near a Building / Facility
• Wind Turbines
• Generates at least a
portion of the Electric Load
• Turbine Generator Sets
• Combustion Turbines
• Micro-Turbines
• Steam Turbines
• Engine Generator Sets
• Fuel Cells
6
Combined Heat & Power (CHP)
A Form of Distributed Generation
CHP is …
ƒ An Integrated System
ƒ Located At or Near a
Building/Facility
ƒ Provides at Least a Portion of the
Electrical Load and
ƒ Recycles the Thermal Energy for
– Space Heating / Cooling
– Process Heating / Cooling
– Dehumidification
Picture Courtesy of UIC
7
Combined Heat and Power
15 - 30 units thermal rejected / lost
100 units
fuel input
Natural Gas
Propane
Digester Gas
Landfill Gas
Coal
Steam
Waste Products
Others
30 -35 units electric
Prime Mover
Generator
Heat Exchanger
40 – 50 units thermal recovered
Thermal System
Key Attribute: Coincidence of Electric and Thermal
Needs
8
Energy Efficiency Benefits of
CHP
9
CO2 Emissions Benefits of
CHP
10
Normal CHP Configuration
ƒ CHP Systems are Normally Installed in Parallel with
the Electric Grid (CHP does not replace the grid)
ƒ Both the CHP and Grid Supply Electricity to the
Customer
ƒ Recycled Heat From the Prime Mover Used for:
–
–
–
–
Space Heating (Steam or Hot Water Loop)
Space Cooling (Absorption Chiller)
Process Heating and/or Cooling
Dehumidification (Desiccant Regeneration)
11
Basic CHP Components
ƒ Prime Mover that generates mechanical energy
– Reciprocating Engine
– Turbine (Gas, Micro, Steam)
– Fuel Cell
ƒ Generator converts the mechanical energy into electrical
energy
ƒ Waste Heat Recovery is one or more heat exchangers that
capture and recycle the heat from the prime mover
ƒ Thermal Utilization equipment converts the recycled heat
into useful heating, cooling, and/or dehumidification
ƒ Operating Control Systems insure the CHP components
function properly together
12
Typical Industrial CHP System
13
Terminology / Conversion Factors
Power
ƒ Power = Rate of Energy (Power ≠ Energy)
System Capacity or Output at a Point in Time
Electric Demand (kW) or Thermal Demand (Btu/hr)
Engine/
Gen Set
Boiler/
Furnace
500 kW system or
1.7 million Btu/hr (e)
80,000 Btu/hr system or
31.4 hp
Conversion Factors:
1 kW = 3,413 Btu/hr
1 hp = 2,545 Btu/hr
14
Terminology / Conversion Factors
Energy
ƒ Energy = Power X Time
Use of the Power ---- Power Delivered Over Time
Engine/
Gen Set
Boiler/
Furnace
500 kW generator operating for 1 hour
delivers 500kWh of electricity or 1.7 million
Btus(e)
80,000 Btu/hr boiler operating for 1 hour
delivers 80,000 Btus of heat
Conversion Factors:
1 kWh = 3,413 Btus
15
Energy Versus Power
ƒ The Power required if you want to light 10 – 100 Watt light
Bulbs = 1,000 Watts = 1 kW (capacity required)
ƒ Turn the lights on for 1 hour ---- Use the Power ---- Power
Delivered Over Time ---- the Energy required to light the bulbs
for 1 hour is 1kW X 1 hour = 1 kWh
Conversion Factors:
Power: 1 kW = 3,413 Btu/hr
Energy: 1 kWh = 3,413 Btus
16
Power versus Energy
Energy
POWER
Rate of Energy
Power X Time
kWh/h = kW
kWh
Btu/h
Btu/h X h = Btu
Conversion Factors:
1 kW = 3413 Btu/h
1 kWh = 3413 Btu
17
What Makes A Good CHP Application?
• Good Coincidence Between Electric and Thermal
Loads
• Large Cost Differential Between Electricity (Grid)
and CHP Fuel --- “Spark Spread”
• Fair / Favorable Regulatory Environment
• Long Operating Hours
• Economic Value of Power Reliability is High
• Installed Cost Differential Between a Conventional
and a CHP System (smaller is better)
18
Candidate Applications for CHP
ƒ Hospitals
ƒ Food Processing Waste
ƒ Colleges / Universities
ƒ Farm Livestock Waste
ƒ High Schools
ƒ Waste Water Treatment
ƒ Residential
Residential Confinement
Confinement
ƒ Landfill Sites
ƒ High Rise Hotels
ƒ Pulp & Paper Mills
ƒ Fitness Centers
ƒ Ethanol / Biodiesel Plants
Anaerobic
Digesters
Other
Biomass
ƒ Chemicals Manufacturing
ƒ Metal Fabrication
19
CHP System Sizes (Terminology)
System
Designation
Size Range
Comments
Mega
50 to 100+ MWe
Very Large Industrial
Usually Multiple Smaller Units
Custom Engineered Systems
Large
10’s of MWe
Industrial & Large Commercial
Usually Multiple Smaller Units
Custom Engineered Systems
Mid
10’s of kWe to
Several MWe
Commercial & Light Industrial
Single to Multiple Units
Potential Packaged Units
Micro
<60 kWe
Small Commercial & Residential
Appliance Like
20
Installed CHP - 2008
ƒ 85,184 MW at approx. 3,364 sites (Nationally)
ƒ Represents approx. 9% of total US generating
capacity
ƒ Saves an estimated 1.9 Quads of fuel per year
ƒ Eliminates over 248 million metric tons of CO2
emissions annually
(equivalent of removing approx. 45 million cars from the road)
21
Over 32 GW of New Capacity
Has Been Installed Since 1995
Capacity Additions, 1995 to Present
Cumulative Capacity Additions (GW)
100
90
80
70
60
50
40
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Source: CHP Installation Database – ORNL/DOE
22
But Growth Has Slowed Since
2005, and Some Existing Capacity
Has Been Retired
Net Capacity Growth, 1995 to Present
Cumulative Capacity Additions (GW)
100
90
80
70
60
50
40
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Source: CHP Installation Database – ORNL/DOE
23
Current Market Conditions
(Midwest)
ƒ Poor spark spread (but getting better)
ƒ Continued fuel price uncertainty
ƒ Utility attitudes
– Tariff structures
– Standby rates
– Deferral rates
ƒ Developing sales/service infrastructure for small CHP
ƒ CHP is a discretionary investment for the user
24
Emerging Market Trends – a Change on the
Horizon?
ƒ Spark spread getting better
ƒ Interest in alternative fuels
ƒ Interest in power reliability and energy
security benefits
ƒ Recognition of CHP by policymakers
– National
– State
ƒ Greenhouse Gas Legislation
25
Module #2
CHP – Technology Building Blocks
26
Combined Heat and Power
15 - 30 units thermal rejected / lost
100 units
fuel input
•Reciprocating Engines
•Industrial Gas Turbines
•Steam Turbines
•Micro-turbines
•Fuel Cells
30 -35 units electric
Prime Mover
Generator
Heat Exchanger
40 – 50 units thermal recovered
Thermal System
27
CHP Prime Movers
ƒ
ƒ
ƒ
ƒ
ƒ
Reciprocating Engines
Industrial Gas Turbines
Steam Turbines
Micro-turbines
Fuel Cells
28
Two Types of Reciprocating Internal
Combustion Engines
ƒ Spark Ignited – Otto Cycle Engines
–Utilizes Gaseous or Easily Vaporized Liquid
Fuels (most common in CHP systems)
ƒ Self Ignited – Compression Ignited – Diesel Cycle
Engines (common in emergency generator sets)
–Utilizes the Full Range of Liquid Petroleum Fuels
–(Distillate through Residual)
29
Four Stroke Spark Ignited Reciprocating
Engine
ƒ Power Generated Thru a Series of 4 Combustion
Stages
– Air / Fuel Intake
– Compression
– Power
– Exhaust
ƒ Two Crankshaft Revolutions per Power Stroke
30
Four Stroke Reciprocating Engine
Spark Plug
Intake Valve
Exhaust Valve
Cylinder
Piston
Connecting Rod
Crankshaft
31
Reciprocating Engines - Spark Ignited
Four-Stroke Engine
Source: GTI Textbook ( Natural Gas-Fueled Cooling
Technologies and Economics )
32
- Thermodynamics
Reciprocating Engines - Spark Ignited
Four-Stroke Engine Operation
1. INTAKE
STROKE:
As piston moves down, a vacuum occurs in the cylinder. The crankshaft
opens the intake valve. Atmospheric pressure pushes the air fuel
mixture through the open intake valve into the cylinder above the
pistons. At the bottom of the stroke the intake valve closes. The
exhaust valve stays closed.
2. COMPRESSION
STROKE
As the piston moves up with both valves closed, the air fuel mixture
becomes highly compressed in the space left between the top of the
pistons and the cylinder head.
3. POWER
STROKE:
Just before the compression stroke ends, a high voltage arc across the
spark plug gap ignites the air fuel mixture. The rapidly burning mixture
produces very high pressure to push the piston down.
4. EXHAUST
STROKE:
As the piston begins to go back up, the crankshaft opens the exhaust
valve and the piston pushes out the burned gases completing the cycle.
Source: GTI Textbook ( Natural Gas-Fueled Cooling Technologies and Economics )
33
Component
Recognition
Picture Courtesy of Caterpillar
34
- Component Recognition
Recognition
Carburetion
Cylinder Heads
Air Intake
Generator
Mounting Rails
Picture Courtesy of Caterpillar
35
Reciprocating Engine - Heat Balance
36
Reciprocating Engines Rules of Thumb
100 – 500
500 – 2,000
24 – 28
28 – 38+
14,000 – 12,000
12,000 – 9,000
4,000 – 5,000
4,000 – 5,000
Steam (@ 15 psig), lbs/h per kW
4–5
4–5
Steam @125 psig, lbs/h per kW
3-4
3-4
(with Heat Recovery)
1,800 – 1,400
1,400 – 1,000
O&M Costs, $/kWh
0.015 – 0.012
0.012 – 0.010
Rich Burn w/3-way catalyst
≈0.5 (30-40)
≈0.5 (30-40)
Lean Burn w/SCR treatment
≈0.5 (2-6)
≈0.5 (2-6)
Capacity Rage (kW)
Electric Generation Efficiency
% of LHV of Fuel
Heat Rate, Btu/kWh
Recoverable Useful Heat
Hot Water (@ 160oF), Btu/h per kW
Installed Cost, $/kW
NOx Emission Levels, lbs/MWH
37
For More Information
Wartzila
ƒ Caterpillar
ƒ Waukesha
ƒ Cummins
ƒ Wartzila
Caterpillar
Waukesha
ƒ Jenbacher
ƒ Fairbanks-Morse
Jenbacher
Fairbanks-Morse
38
CHP Prime Movers
ƒ
ƒ
ƒ
ƒ
ƒ
Reciprocating Engines
Industrial Gas Turbines
Steam Turbines
Micro-turbines
Fuel Cells
39
Gas Turbine - Uses
ƒ Aircraft
ƒ Power Generation
– Electric Power Plants
– Marine Power Applications
– CHP
• Second Most Commonly Used CHP Prime Mover
• Generally Used in Larger Systems (>4 MW)
• Used When High Quality Waste Heat Required
(High Pressure Steam)
40
How a Gas Turbine Works
1. Intake Air
2. Compress Air
3
3. Heat Up the Air
by Burning Fuel
4. Re-Expand the
Hot Air
2
Compressor
4
1
41
How Can That Work?
• As the Hot Gas Expands Thru the
Turbine – The Gas Pushes the Turbine
Around
• This Develops Power
• Drives BOTH
– the Compressor and
– the Load
42
Some Peculiarities
ƒ Turbine Run at VERY High Speeds
ƒ 15,000 to 20,000 RPM Not Unusual
Power = Torque X Speed
ƒ Torque is the Twisting Force on a Shaft
ƒ The Higher the Torque, the Heavier the Shaft and All the Rotating
Parts Have to Be.
ƒ High Speed Means Only Low Torque is Needed
– High Power Output Thru Very Small Lightweight
Shafts and Components
ƒ Result High Power from Small Lightweight Engine
43
Small Packages
ƒ Turbine Here is Roughly 2 feet in Diameter
ƒ Output is 7 MW (~10,000 HP)
Solar Turbine
44
Small Packages (cont.)
45
Example: Solar Gas Turbine
46
Gas Turbine Rules of Thumb
1,000 – 10,000
10,000 – 50,000
24 – 28
31 – 36
14,000 – 12,000
11,000 – 9,500
5,000 – 6,000
5,000 – 6,000
Steam (@15 psig, lbs/h per kW
5–6
5–6
Steam @125 psig, lbs/h per kW
4-5
4-5
(with Heat Recovery)
1,500 – 1,000
1,000 – 800
O&M Costs, $/kWh
0.008 – 0.007
0.008 – 0.005
Without Treatment
1.18
1.18
With SCR
0.47
0.47
With SCR and Oxidation Catalyst
0.073
0.073
Capacity Rage, kW
Electric Generation Efficiency
% of LHV of Fuel
Heat Rate, Btu/kWh
Recoverable Useful Heat
Hot Water (@ 160oF), Btu/h per kW
Installed Cost, $/kW
NOx Emission Levels, lbs/MWh
47
Efficiency of Gas Turbines
Efficiency is stated either in:
Percent
Or
Btu/kWh (referred to as “Heat Rate”)
To Convert:
% Efficiency = 3413 Btu/kWh / Heat Rate (Btu/kWh)
Heat Rate (Btu/kWh) = 3413 Btu/kWh / Efficiency (%)
48
Micro-turbines
ƒ Consist of a compressor, combustor, and turbine
49
Microturbine Basics
ƒ Microturbines are very small combustion turbines.
ƒ Based on engine turbocharger technology with
recuperator (to increase efficiency)
ƒ In most configurations the microturbine and generator
are connected on the same shaft and spin at high
speeds (up to 100,000 rpm). This requires the
generator output to be rectified first to direct current and
then converted to 60 Hz.
ƒ They can burn a variety of fuels but generally the
source is natural gas or landfill gas.
ƒ As inlet air temperature rises above 59o F, the output
capacity is derated and the efficiency decreases
50
Microturbine Performance
51
Microturbine Examples
ƒ Capstone Turbine Corporation
– 30 kW & 60 kW, larger units in development
– Special biogas capable models available
ƒ Ingersoll Rand Energy Systems
– 250 kW
– Uses gaseous fuels with wide range of energy
content (350 to 2500 Btu/scf)
ƒ Elliott Energy Systems
– 80 kW
ƒ Bowman Power Systems
– 80 kW
ƒ Turbec
– 100 kW
52
53
Adding Heat Recovery
ƒ Most equipment compatible for use with heat recovery
Capstone
Capstone microturbines
microturbines with
with aa Unifin
Unifin
heat
heat recovery
recovery unit
unit for
for water
water heating
heating
custom
custom built
built for
for application.
application.
54
Rule of Thumb Micro-turbines
Capacity Rage, kW
100 – 400
Electric Generation Efficiency
% of LHV of Fuel
Heat Rate, Btu/kWh)
25 – 30
13,700 – 11,400
Recoverable Useful Heat
Hot Water (@ 160oF), Btu/h per kW
6,000– 7,000
Steam (@ 15psig), lbs/h per kW
N/A
Steam @125 psig, lbs/h per kW
N/A
Installed Cost, $/kW
(with Heat Recovery)
2,000 – 1,000
O&M Costs, $/kWh
0.015 – 0.01
NOx Emission Levels, lbs/MWh
< 0.49
55
- Cogeneration Technology for the Industrial Sector
Industrial Steam Systems
56
Steam Turbine
ƒ Steam turbines operate differently than other CHP prime
movers. Fuel is not combusted in the turbine, rather in a
boiler that produces the steam.
ƒ The turbine extracts heat from the steam and transforms the
heat into mechanical work by:
– Expanding the steam from high pressure to low pressure
57
Steam Turbine Characteristics
ƒ High pressure steam flows thru the turbine blades
ƒ Turbine shaft is connected to an electric generator
ƒ Power output is proportional to the steam pressure drop in
the turbine
ƒ No emissions from the turbine (emissions may occur from
the boilers that produce the steam)
58
Steam Turbines
Two Classes of Steam
Turbines of Interest to CHP
Systems:
¾ Condensing Turbines
¾ Non-Condensing
(Backpressure) Turbines
59
Condensing Steam Turbine Types
ƒ Simple Condensing (Straight Through)
– Steam exhausts at sub-atmospheric pressure to
condenser
– Produces maximum useful work (electrical or mechanical)
per pound of steam input
60
Backpressure Steam Turbines
ƒ Steam exhausts at above atmospheric pressures suitable for other
steam applications
ƒ Produces less useful work than a condensing turbine
ƒ Useful work produced is inversely proportional to the exhaust
pressure
ƒ Focus on CHP applications
Low Pressure Steam
(above atmospheric)
Low Pressure Steam Load
61
- Cogeneration Technology for the Industrial Sector
Industrial – Steam Systems
62
Backpressure Steam Applications
63
BACKPRESSURE
CONDENSING
Rules of Thumb - Steam Turbines
Electric Generation Efficiency, %
Steam Exhaust Pressure
Steam Required, lbm/hr per kW
Installed Cost*, $/kW
O&M Costs, $/kWh
NOx Emission Levels, lbs/MWH
Electric Generation Efficiency, %
Steam Required, lbm/hr per kW
Installed Cost*, $/kW
O&M Costs, $/kWh
30-40
Below atmosheric
7-10
$500-$700
0.0015-0.0035
Not Applicable
15-35
At or above
atmospheric
See Figure 2-6
$300-$400
0.0015-0.0035
NOx Emission Levels, lbs/MWH
Not Applicable
Steam Exhaust Pressure
64
CHP Prime Movers
ƒ
ƒ
ƒ
ƒ
ƒ
Reciprocating Engines
Industrial Gas Turbines
Steam Turbines
Micro-turbines
Fuel Cells
65
Fuel Cells
HEAT AND
WATER
CLEAN
EXHAUST
Natural
Gas
Fuel
Reformer
Hydrogen
Rich Fuel
Power
Section
Air
Source: Midwest CHP Application Center
DC Power
Power
Conditioner
AC
Power
Standard Power:
480 Volts, 3 phase,
3 wire, 60Hertz
66
Fuel Cells
Key Components
OUTPUT
ELECTRICITY
Load
Oxygen
H
+
O2
Hydrogen
H2
H
+
O2
H2O
H2
Electrolyte
Membrane
Anode (-)
Source: GTI
H2O
Exhaust
Cathode (+)
67
Fuel Cells
Key Components (Physical Arrangement)
Source: DOD Website: www.dodfuelcell.com
68
Fuel Cell Stack
Internal fuel cell stack (similar in most systems)
Individual fuel cells comprise a fuel cell stack
69
Fuel Cell Types
ƒ Phosphoric Acid
ƒ Molten Carbonate
ƒ Solid Oxide
ƒ Proton Exchange Membrane (PEM)
70
Fuel Cells
Rules-of-Thumb
F u e l C e ll
Type
A v a ila b ility
E ffic ie n c y
O p e ra tin g
T e m p e ra tu re
H eat
U tiliz a tio n
P h o s p h o ric
A c id
(P A F C )
C o m m e r c ia l
> $ 3 ,5 0 0 /k W
38 – 45%
4 80 °F
H o t W a te r
S o lid O x id e
(S O F C )
D e m o n s tr a tio n
40 – 45%
1 ,8 0 0 ° F
M o lte n
C a rb o n a te
(M C F C )
D e m o n s tr a tio n
50 – 60%
1 ,2 0 0 ° F
P ro to n
Exchange
M e m b ra n e
(P E M )
D e m o n s tr a tio n
33 –45%
175°F
Source: DOE CHP Resource Guide (September 2003)
H ig h
P re s s u re
S te a m
M e d iu m to
H ig h
P re s s u re
S te a m
H o t W a te r
71
Which Prime Mover to Use
ƒ Recip. Engine --- Provides Hot Water / Low Pressure Steam
--- 5 kW to 10 MW in Capacity
ƒ Industrial Gas Turbines --- Provides High Pressure Steam,
Usually over 3 to 4 MW in Capacity --- 10s of MW for CHP
Applications
ƒ Steam Turbines --- Large Industrials with Waste Streams,
Large Pressure Drop Requirements --- Up to 500 MW
Capacity
ƒ Micro-Turbines --- Provides Hot Water (≈ 500o F Exhaust),
Fuel Flexibility, Compact Size --- 25 kW to 400 kW in
Capacity
ƒ Fuel Cells --- Extremely Clean, Very Expensive, --- 250 kW
modules integrated into systems delivering 10s of MW.
72
Rule of Thumb
Which Prime Mover to Use – T/P Ratio
1. Determine Thermal Use
a. Sum # of therms purchased over last 12 months of bills
Therms
b. Multiply a by 100,000 to get thermal Btus purchased
Btus
c. Multiply Btus purchased by Boiler Eff. (typical 80%) – Btus
used
Btus
2. Determine Electric Power Use
d. Sum # of kWh used over last 12 months of bills
kWh
e. Multiply by 3,413 Btu/kWh to get Btus purchased / used
Btus
3. Determine T/P Ratio
f. Divide total thermal (c) by total electric (e)
T/P
73
Rule of Thumb
T/P Ratio
If T/P =
0.5 to 1.5
Consider Engines
1 to 10
Consider Gas Turbines
3 to 20
Consider Steam Turbines
- If T/P is between 1 and 10 & generator capacity > 1,000kW,
choose industrial gas turbine
- If T/P is between 1 and 10 & generator capacity < 1,000kW,
choose micro-turbine
74
Combined Heat and Power
15 - 30 units thermal rejected / lost
100 units
fuel input
30 -35 units electric
Prime Mover
Generator
Heat Exchanger
40 – 50 units thermal recovered
Thermal System
75
Normal CHP Configuration
ƒ CHP Systems are Normally Installed in Parallel with
the Electric Grid (CHP does not replace the grid)
ƒ Both the CHP and Grid Supply Electricity to the
Customer
ƒ Recycled Heat From the Prime Mover Used for:
–
–
–
–
Space Heating (Steam or Hot Water Loop)
Space Cooling (Absorption Chiller)
Process Heating and/or Cooling
Dehumidification (Desiccant Regeneration)
76
Generators
ƒ CHP systems utilizing recip. engines, gas turbines, or
steam turbines convert mechanical shaft power to
electricity thru the use of an electric generator
ƒ Generators produce AC power on the principle that voltage
is induced in a wire held in a rotating magnetic field
ƒ The amount of voltage induced is proportional to
– Strength of the magnetic field
– Speed of the rotation of the wire relative to the magnetic field
ƒ Frequency of the Power is Proportional to the Speed of the
Generator (rpm)
77
Two Types of Generators
Induction
Synchronous
• Requires External Power
Source to Operate (Grid)
• Self Excited (Does Not Need
Grid to Operate)
• When Grid Goes Down,
CHP System Goes Down
• CHP System can Continue to
Operate thru Grid Outages
• Less Complicated & Less
Costly to Interconnect
• More Complicated & Costly
to Interconnect (Safety)
• Preferred by Utilities
• Preferred by CHP Customers
78
Inverters
ƒ CHP systems that utilize fuel cells, or microturbines employ inverter technology to produce
utility grade power
ƒ Devices that convert DC power to AC power
ƒ Inverter voltage & frequency automatically
synchronize with the utility grid
ƒ When the grid goes down, the inverter based CHP
system goes down
79
Grid Interconnection
ƒ Any CHP Interconnection Must
Address:
– Safety of customers, line
workers, general public
– Integrity of the grid & quality
of service
– Protection of equipment
– System Control by the utility
80
ƒ Interconnection – Not a Technical Issue
– Technology exists to safely connect to any type
grid
– Most utilities provide example “tie ins”
ƒ Interconnect – Cost & Utility Acceptance Issue
– True cost varies with interconnect complexity
– Utility resistance can add significant cost
• Studies
• Hardware
81
Grid Interconnection Standards
ƒ Institute of Electrical and Electronic Engineers
(IEEE) has developed standardized technical
interconnection protocols (IEEE 1547)
ƒ States are adopting IEEE 1547 and developing
rules for implementation within their state
Source: USEPA CHP Partnership (May 2007)
82
Combined Heat and Power
15 - 30 units thermal rejected / lost
100 units
fuel input
30 -35 units electric
Prime Mover
Generator
Heat Exchanger
40 – 50 units thermal recovered
Thermal System
•Space & Process Heating
•Absorption Chillers
•Desiccant Dehumidifiers
83
Heat Recovery (Recycled Energy)
ƒ Hot Exhaust Gases
– Direct
– Steam, Hot Water, Air
84
Thermally Activated Machines
ƒ Space and Process Heat Systems
ƒ Absorption Chillers / Refrigeration Systems
ƒ Desiccant Dehumidifiers
85
Space and Process Heating
ƒ Reject / Recycled Heat From the CHP System:
– Heat the Feed Water to a Boiler
– Hot Water Used Directly for Process Heating
– Steam Injected into a Steam Loop
– Steam Used Directly for Process Heat, Steam
Turbine Drive, etc
86
Electric Vapor Compression Cycle
ƒ Compressor Raises Pressure of Refrigerant Vapor
ƒ Refrigerant Liquefies in Condenser
ƒ Refrigerant Boils in Evaporator – Cooling Chilled Water
Chilled Water
Actual Chiller
Components
88
Electric Chiller System
89
Recognition - Typical Cooling Tower
90
Electric Chiller System
91
How It Fits in the Building
ƒ Typical Chilled Water System
– Chiller Sends Cold Water to Cooling Coils
– Coils Cool Air as Needed for Each Space
– Chiller Rejects Heat to Cooling Tower
92
Absorption Chillers
ƒ CHP Systems Can Provide Chilled Water Through
Absorption Chiller Technology
ƒ Refrigeration Cycle Is the Same as Electric Chillers
ƒ Major Differences are:
– Electric/Mechanical Compressor Replaced with
an Absorber/ Generator
– Refrigerants are Different
ƒ Absorption Chillers can be Direct Fired or Indirect
Fired (Indirect Fired are Used in CHP Systems)
93
Schematic Diagram
Basic Absorption Cycle Components
Condenser
Generator
Cooling
Tower
Water
(Inlet)
(Refrig. Vapor)
Heat
Input
(Refrig. Liquid)
(Weak
Solution)
Heat
Exchanger
(Strong
Solution)
Expansion
Valve
Refrigerant
Pump
(Refrig. Vapor)
Cooling
Tower
Water
(Inlet)
Absorber
Evaporator
Chilled
Water
94
New Single-Stage
ASME Rated
Generator
Stainless Steel Mist
Eliminators
Condenser
Fixed & Floating Tube
Supports
Low Temp.
Generator
Evaporator
Absorber
Solution Heat
Exchanger
Source: Trane Co.
Distribution Spray
95
How It Fits in the Building
ƒ Absorption Chiller Chilled Water System
– This is the Type of Large Commercial Systems
Suited to Absorbers
– Absorber Replaces Electric Chiller
96
More Modern Hybrid Design
ƒ Absorption/Electric Hybrid System
– Absorber Does the Bulk of the Cooling
– Electric Chiller Only for Peak Days
97
Desiccant Dehumidification
ƒ Humidity control is important in many applications:
– Manufacturing
– Space Cooling
– Minimizing Mildew, Mold, Fungus
ƒ Desiccants remove humidity (latent load) from air
ƒ Two types of desiccant dehumidifiers are
commercially available:
– Solid Desiccants
– Liquid Desiccants
98
Desiccant Dehumidification
Active Desiccant Wheels
Desorption
Reactivation Air
Exiting
Desiccant Heater or
CHP Reject Heat
Reactivation Air
Entering
exhausted after passing
through wheel
wetter, cooler
Process Air
Exiting
Process Air
Entering
drier, warmer
humid
Sorption
99
Desiccant Dehumidification
Liquid Desiccant System
Drier Air to
Building
Conditioner
Regenerator
Coolant
Humid
Outside
Air
Hot and
Humid Air
to Outside
Heat
Outside Air
100
CHP Equipment, What Have We Covered?
ƒ Prime Movers
– Recip. Engines, Turbines, Fuel Cells
ƒ Generators
– Synchronous, Induction, Inverters
ƒ Heat Recovery
– Steam, Water, Air
ƒ Thermal Equipment
– Space/Process Heat, Absorption Chillers,
Desiccant Dehumidifiers
101
Contact Information
John Cuttica
University of Illinois at Chicago
Midwest CHP Application Center
312/996-4382
[email protected]
www.chpcentermw.org
102
103