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|
Design
Tips - Building and Site Requirements
This
section describes the requirements involved in interfacing
modular integrated energy systems (IES) with conventional
building systems. This document is not intended to be a design
guide for these building and site interfaces (which is the
responsibility of the cognizant design engineer who is applying
a Reference Design to a particular building). The Reference
Designs are based on 2MW to 5MW Solar gas/diesel turbine generators,
heat recovery boiler(s) with duct firing, and Broad USA heater/chiller(s)
serving a variety of load scenarios and generic facilities.
As such, the focus of this document is on identifying the
kinds of conventional systems that are compatible with the
Reference Designs, and provides a list of design resources
that practitioners can use in applying modular IES technology.
An illustration of key building interfaces is shown below.
Additional discussion is presented in each section.
Background
Introduction
The
information presented here is the results of technical work
being performed for developing packaged system designs for
large (2 to 5 MW) building cooling, heating, and power (BCHP)
Systems, also known as Integrated Energy Systems (IES). This
work is funded by the U.S. Department of Energy and is being
administered by Oak Ridge National Laboratory (ORNL Subcontract
4000011476). Honeywell and its team members, Broad USA, I.C.
Thomasson, and the Chelsea Group, are developing a set of
CAD-based packaged IES system designs and a supervisory control
and optimization capability for these systems. This section
covers the work performed under Task 2.1: Building & Site
Requirements.
Project
Overview
The
objective of the program that developed the information in
this section was to develop large (2 to 5 MW) BCHP packaging
technologies and field-test a prototype system. These technologies
include a set of “reference” CAD designs and an
optimizing supervisory control system. Installation scenarios
for these systems can vary widely, so packaging is dependent
on modularity, namely, the ability to construct a system by
choosing from a selection of compatible components with standardized
interfaces. This is especially important for larger BCHP systems,
where the physical size of the equipment prohibits the manufacture
and shipment of the entire system in one enclosure. Packaging
in this way still simplifies the design and installation process
by reducing the amount of site-specific engineering and site
preparation required.
This project was focused on BCHP packaged systems in the 2-
to 5-MW size range, with 500 to 2000 tons of cooling, intended
for central plant and district energy applications serving
multiple buildings. The major modules are a turbine-generator,
a heat recovery steam generator, and an absorption chiller.
The set of “reference” packaged designs to be
developed will allow these modules to be applied to a variety
of customer sites.
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To Top
Codes
and Standards
| The
purpose of this section is to provide the reader with
a overview of the codes and standards that will generally
apply to a CHP plant. By no means is this list comprehensive. |
| 1. |
Building
Codes |
| |
| • |
International
Building Code (IBC), developed as a model code for
model code organizations:BOCA, UBC, SBC |
| • |
State
& local codes |
|
| 2. |
Mechanical
Codes & Standards |
| |
2.1 |
ANSI
Standards |
| |
|
| • |
Flanges
and piping B16.5, B16.1, B16.47, etc. |
|
| |
2.2 |
ASHRAE
Standards |
| |
|
| • |
Guideline
1-1996 The HVAC Commissioning Process |
| • |
Std
15-2001 Safety Standard for Refrigeration Systems |
| • |
Std
62-2001 Ventilation for Acceptable Indoor Air Quality |
| • |
Std
114-1986 Energy Management Control Systems Instrumentation |
| • |
Std
135-2001 BACnet - A Data Communication Protocol
for Building Automation and Control Networks |
| • |
Std
147-2002 Reducing the Release of Halogenated Refrigerants
from Refrigerating and Air-Conditioning Equipment
and Systems |
|
| |
2.3 |
ASME Standards |
| |
|
| • |
Boiler
Power Piping 31.1 |
| • |
Chemical
Process Piping 31.3 |
| • |
Boiler
and Pressure Vessel Code |
| • |
Pipe
Flanges and Flange Fittings B16.5 |
|
| |
2.4 |
ASTM
Standards |
| |
|
These
are generally equipment standards and pertain to individual
components of the CHP system |
| |
2.5 |
UL
Standards |
| |
2.6 |
State
& Local Code |
| |
|
A
number of large municipalities (Chicago, New York City)
maintain their own codes |
| 3. |
Electrical
Codes & Standards |
| |
3.1 |
IEEE |
| |
|
| • |
Interconnection
Standard 1547 |
| • |
DG
Standard 1589 |
| • |
IEEE
Standards 519-1992, 929-2000, 84 (Harmonic Limits
and Voltage Fluctuations, Waveform) |
|
| |
3.2 |
National
Electric Code (NEC) |
| |
3.3 |
ASTM
Standards |
| |
|
These
are generally equipment standards and pertain to individual
components of the CHP system |
| |
3.4 |
UL
Standards |
| |
3.5 |
State
& Local Codes |
| |
|
A
number of large municipalities (Chicago, New York City)
maintain their own codes |
| |
3.6 |
State
& Local Codes |
| 4. |
National
Fire Protection Agency (NFPA) Codes |
| |
| • |
Gas-Fired
Equipment Code 8501 |
| • |
Oil/Diesel-Fired
Eqipment Code 31 |
| • |
National
Gas Fuel Code (NFPA 54) |
| • |
Liquid
Fuel Storage Tanks Code (NFPA 30) |
|
Back
To Top
Electrical
Interconnections
| The
electrical equipment of the CHP facility, though not the
most expensive part of the construction, is vital in the
operating success of the facility, and is probably the
most complicated and diverse part of the design. In most
facilities there are two major areas of focus, the utility
interface point and the CHP construction itself. We will
consider these two points as separate parts of the design
and in many cases may be remote from each other by a substantial
distance. |
1. |
Utility Interface Point |
|
The
interface point is usually located close to or within
the distribution substation for the facility. The following
upgrades are usually considered in the design of this
point of intersection. |
2. |
Low-Med
Voltage/Station Power Capacity |
|
The
CHP facility consumes power itself to operate. Although
supplied by the CHP equipment itself through transformers,
often an additional feed is used to provide this power
from the utility during startup. A new standby generator
may also be used. |
3. |
High
Voltage-Substation |
|
The
CHP plant connects to the grid at the substation; sufficient
space must be present for the switchgear and transformers
required. |
|
3.1 |
Over
/ Under Voltage Protection |
|
|
It
is usually critical for the cogeneration facility. The
utility normal mode of design is to avoid voltage drop
so they operate their distribution system at a higher
than nominal level so that nominal levels can be maintained
on the extended reaches of the distribution system. Cogeneration
equipment removes load or may even export power removing
voltage drop or creating voltage rise thereby driving
the site into higher than normal voltage levels. Some
utilities take an unrealistic, bureaucratic approach with
mandatory trip requirements while operating at very high
voltage levels. To avoid nuisance tripping of the interface
breaker a fast acting, over voltage relay (ANSI Device
59) is required. |
|
3.2 |
Under
Voltage Relaying |
|
|
Under
voltage relaying (ANSI Device 27) also required is usually
not as critical as over voltage control. |
|
3.3 |
Out
of Frequency - Over/Under Frequency Protection |
|
|
Out
of frequency / over/under frequency protection (ANSI Device
81 O/U) is also important. The first signs of system instability
occur in the system operating frequency. For a cogeneration
plant operating in parallel the frequency is set by the
utility. The system frequency protection should be set
outside the utility trip points and set for on site equipment
protection only. In the unlikely event of utility grid
instability the cogeneration equipment should stay on
line to avoid placing the facility load on a utility tending
toward instability. Utility guidelines may be obtained
to assist in making these determinations. |
|
3.4 |
Out
of Step Protection |
|
|
Normally
any breaker interfacing between the utility and the cogeneration
must be equipped with a Sync-check relay, (ANSI Device
25). This relay will be capable of monitoring the voltage
via potential transformers (PT) on the line and load side
of the device. The protective relay will prevent closing
the breaker unless the voltages levels are the same and
the both systems are in phase. If the co generation plant
were accidentally connected to the utility out of phase,
the two systems would attempt to instantly align themselves
with other. This would cause major stress on the mechanical
and electrical equipment operating on the site. |
|
3.5 |
Reverse
Power Protection |
|
|
Reverse
power protection may be required on facilities, which
have not negotiated a power sell agreement with the utility.
The reverse power relay (ANSI Device 32) monitors the
direction of power flow and will, after a time delay,
initiate a trip when power flows from the site to the
utility grid. There is an option to either trip the site-interconnecting
breaker or trip the generating equipment causing the reverse
power. It is usually less disruptive to trip the generating
equipment and suffering the impact of the increased power
use penalties from the utility than to take the entire
site off line. This however is not always the case, and
must be analyzed for each site. |
| |
3.6 |
Detecting
Unintentional Island Operation |
|
|
The
condition of unintentional island operation may occur
when the facility load is approximately equal to the output
of the cogeneration equipment. Under this condition, if
a utility breaker upstream opens it may be difficult for
the relaying at the interface point to detect that the
utility is no longer connected. As long as the load is
closely matched to the generators output the facility
will continue to operate until a load change pushed the
generator voltage or frequency out of the protection zone
provided by the interconnecting relaying. Under this condition
the facility may remain energized for several minutes
creating the possibility of the upstream breaker reclosing
on the facility out of phase or a possibly unsafe condition
for utility maintenance workers. This condition does not
occur during a fault since the fault energy would pull
the generation equipment down, taking the CHP off line.
|
|
3.7 |
Power
Import / Export Power Control |
|
|
One
feature that becomes vital in cogeneration facilities
is the use of feed back control to limit the amount of
power purchased from the utility. This is accomplished
by sending a signal from the utility interface breaker
to the CHP. Based on this feed back signal the turbine
controls continually adjust the governor to maintain a
fixed amount of power flowing through the utility interconnect
breaker. This is modified only by the limits of the CHP
generator. |
|
3.8 |
Reactive
Power Import / Export Power Control |
|
|
A
similar control function may be accomplished by monitoring
the amount of reactive power purchased from the utility.
The feed back signal from the interface breaker to the
CHP allows the voltage regulator to be continuously adjusted
to maintain a constant power factor across the utility
main breaker. Protective features must be supplied for
the generator controls to prevent over exciting the generator.
The additional cost for this control feature may be recovered
from utility charges against reactive power purchases. |
4. |
The
CHP Electrical Design Considerations |
|
4.1 |
Distribution
System Configuration |
|
|
The
first consideration for a new CHP is the configuration
of the distribution system to which it is connected. The
presence or absence of a neutral in the distribution system
will determine how the cogeneration equipment is connected
to the system. Another consideration is to whether the
system will be operated as an island or not. The presence
of a neutral indicated that transformers are connected
wye on the primary side. If this is the case an Isolating
transformer will be required since the generator is not
a good source for generating neutral currents. |
|
4.2 |
The
Isolating Transformer |
|
|
The
isolating transformer for the CHP cogeneration equipment
allows an exact match between the site distribution and
the generator output. It also provides a level of isolation
between the generator and exposed distribution. Typically
the wye connection faces the distribution system to supply
ground faults and neutral currents, and the delta faces
the generators to provide isolation. The generator is
typically connected wye and grounded through a reactor
or resistor that establishes the ground reference on the
generator side. |
|
4.3 |
Generator
Bus |
|
|
The
generator can operate on an electrically isolated bus
or can supply auxiliary CHP loads. If the generator bus
is used to supply other loads a grounding bank to establish
the generator bus ground reference must be installed for
those situations when the CHP auxiliary loads are operating
and the turbine generator is not in operation. |
|
4.4 |
Underground
Distribution System |
|
|
If
the cogeneration equipment is connected to an underground
distribution system, not exposed to lightning flash over
events, and the system has no neutral the turbine generator
can be connected to the distribution system without an
isolating transformer. When this is the design care must
be taken to properly ground the generator or specify the
proper generator construction to avoid harmonic currents
circulating between the distribution system and the utility
distribution system. The pitch of the generator windings
must match those of the utility system, typically 2/3.
This type of construction is more expensive for this size
alternator. Another option is to purchase a standard alternator
and mitigate the harmonic currents that can result by
increasing the impedance in the generator neutral connection.
This should be carefully considered since the installation
can impact the performance of lightning arresters in the
distribution system. |
|
4.5 |
Synchronizing
Switchgear Requirements |
|
|
4.5.1 |
Synchronizing
Switchgear |
|
|
|
Synchronizing
switchgear is a piece of electrical switchgear constructed
in such a manner to interface the generation equipment
to the electrical distribution system. This gear contains
the synchronizing breaker and all of the protective relaying
required for protecting the alternator from electrical
disturbances that occur on the distribution system. The
location of this equipment in the electrical configuration
for the CHP is between the generator and the first distribution
bus upstream. In some cases the isolating transformer
cam be placed between the synchronizing breaker and the
alternator. |
|
|
4.5.2 |
Synchronizing |
|
|
|
Synchronizing
is the operation of adjusting the generator voltage to
match the line voltage, aligning the generator phase angle
to match the utility and closing the synchronizing breaker.
The turbine control equipment performs this operation
automatically. Provision is also provided for manual override
in the event that the automatic system fails. The manual
system consist of volt meters with selection for line
and generator voltage comparison; sync-scope for monitoring
each system phase relationship; sync-lights which are
not illuminated when the two systems are in phase; manual
voltage and speed switches, raise and lower; and a manual
switch to close the synchronizing breaker. |
|
|
4.5.3 |
Protective
Relaying |
|
|
|
Protective
relaying for the typical generator protection package
may consist of the following. Presently many of these
functions are housed in a multifunction, microprocessor
protective relay. |
|
|
|
4.5.3.1 |
Sync-check
relay |
|
|
|
|
Sync-check
relay, (ANSI Device 25). This relay will be capable of
monitoring the voltage on the line and load side of the
device. The protective relay will prevent closing the
breaker unless the voltages levels are the same and the
both systems are in phase. |
|
|
|
4.5.3.2 |
Voltage
restrained overcurrent (ANSI Device 50/51V) |
|
|
|
|
This
feature protects against generator overload and faults
in the generator and the distribution system. If the voltage
in the generator collapses during a fault the voltage
restrained feature decreases the trip point value by seventy
five percent. |
|
|
|
4.5.3.3 |
Ground
overcurrent (ANSI Device 50/51G) |
|
|
|
|
This
feature protects against ground faults in the generator
and the distribution system. |
|
|
|
4.5.3.4 |
Differential
overcurrent protection (ANSI Device 87) |
|
|
|
|
Current
transformers (CT) monitor the currents entering and leaving
the zone of protection and trips if the values differ
more than the set point value. CTs are located on the
load side of the synchronizing breaker and the neutral
side of the alternator. |
|
|
|
4.5.3.5 |
Reverse
power (ANSI Device 32) |
|
|
|
|
This
device monitors the direction of power flow and will,
after a time delay, initiate a trip when power flows from
the distribution system to the generator. |
|
|
|
4.5.3.6 |
Over
/ under frequency protection (ANSI Device 81 O/U) |
|
|
|
|
This
function trips if the generator frequency is outside the
relay set point range of protection. |
|
|
|
4.5.3.7 |
Over
under voltage protection (ANSI Device 27 / 59) |
|
|
|
|
This
function trips if the generator voltage is outside the
relay set point range of protection. |
|
|
|
4.5.3.8 |
Loss
of excitation (ANSI Device 40) |
|
|
|
|
This
function trips if the generator power factor is outside
the relay set point range of protection. |
|
|
|
4.5.3.9 |
Volts
/ hertz protection (ANSI Device 24) and inadvertent generator
energization (ANSI Device 50 / 27) |
|
|
|
|
These
features provide off line protection features that protect
against generator voltage regulator malfunction with the
generator running but not synchronized to the utility. |
5. |
Possible
Utility Power Requirements |
| |
| • |
IEEE
519-1992, 929-2000, 84 (Harmonic Limits and Voltage
Fluctuations, Waveform) |
| • |
Power
Factor, Voltage, Frequency, Harmonic Distortion,
Voltage Flicker, Waveform Distortion, Phase Imbalance
Limitations |
| • |
IEEE
1547 Standards for DC Injection, Immunity Protection,
Surge Capability |
|
6. |
Island
Mode |
|
The
installation of an on-site electric generating facility
requires an interconnection agreement between the facility
operator and the local electric utility before a generator
can be connected with the electrical service. When electric
power from the on-site facility is substantial enough,
the interconnection facility and supporting agreement
may enable the operator to function in “island mode,”
delivering a number of significant advantages. Island
mode involves removing a piece of equipment or the entire
facility’s electrical load from the electrical grid
and serving it directly from the engine-generator, with
no interconnection or ability to take power from the electric
utility. This is vital when the industrial facility or
commercial/institutional operation cannot afford even
momentary outages, or when it requires exceptionally high-quality
electric power. Firms engaged in high-quality electro-plating,
for example, may require an hour or more downtime before
production can resume after a power outage of just a few
seconds duration. For them, island operation represents
insurance against unforeseen and expensive production
downtime. At its most basic, island mode requires no interconnection
equipment or switchgear to access the power grid. This
is rarely a practical option, however, since power from
the utility must be available when the engine generator
is down for maintenance or when the facility’s load
exceeds that produced by the generator. An improperly
sized engine-generator, for example, may be unable to
handle demand spikes caused by certain types of equipment
such as motors that can draw three times their rated electrical
demand during startup. While reliability and power quality
are primary drivers in selecting a natural gas-fueled
electric generating or CHP (Combined Heat & Power)
installation, sufficient bottom-line savings may add to
the appeal and reduce the payback time |
7. |
Black
Start |
|
Black
start is the procedure for recovery from total or partial
shutdown of electrical supplies throughout the country’s
national transmission system or supplier distribution
network. A little additional outlay on capital cost to
ensure back-up for potential systems failure can prove
to be a time and money-saving option. All power stations,
with the possible exception of small hydro-electric generating
stations, need an electrical supply to start up. To be
able to black start, a station must have some form of
independent auxiliary supply with sufficient capacity
to supply the unit auxiliaries while a main generator
is prepared for operation. This additional power source
is usually provided by a smaller peripheral black start
generating plant, which is started from a battery or other
energy storage device. Once operational, the power plant
can then be used to energize part of its local network,
providing supplies for other plant within the area to
enable them to start-up. For partial or total shutdown
of the transmission system, the general principle of recovery
includes re-establishment of isolated power stations to
provide ‘power islands’; these are then integrated
into larger sub-systems eventually allowing the re-instatement
of the whole national grid system. By having this capability
at a number of strategically located sites, electrical
supplies can be rapidly restored. Back-up diesel or turbine
sets for black starting the main generating plant used
to be a common occurrence at power stations. The reasons
for the lack of these facilities at most modern plants
can be technical, but more often than not they are commercial
- the extra capital costs for black starting can be prohibitive.
Plant and grid failures are few but power companies and
plant managers need to bear in mind that accidents and
systems failures do occur. Without black starting, re-establishing
the supply system can be difficult, severely delayed and
therefore costly. Investing in a secure back-up is essential
to minimize the consequences of system failure. |
8.
|
Meeting
Local Utility Standards |
| |
Every
local power utility has their own set of interconnection
requirements which must be researched and met. While utilities
are currently developing uniform standards to guide CHP
interconnection (California rule 21 for example), facilities
currently must design unique equipment scenarios for each
plant. Major power utility requirements include grid connection,
condition of power, switchgear and transformer access,
and meter access. |
Back
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Instrumentation
1. |
Supervisory
Control |
| |
Evaluate
existing control system for ability to expand and supervise
new equipment packages. Data links may be established
to new controls furnished with packaged system for data
acquisition and supervisory set points. |
2. |
Possible
New Plant Steam Master for Brownfield Sites |
| |
For
plants with existing steam producing boilers, consider
integrating the new HRSG into existing coordinated boiler
control strategies. Coordination of some type will be
required to allow the units to share steam loads without
causing instability between the units. |
| |
|
Option
No. 1 – Expand existing controls to include new
requirements including steam master and new balance of
plant (BOP) auxiliaries |
| |
|
Option
No. 2 – Replace all plant controls if outdated |
| |
|
Option
No. 3 – Relatively few interconnect points required
for coordinated control. Hardwire necessary interconnections. |
| |
|
Option
No. 4 – For coordinated control and more extensive
data acquisition, investigate options and implement communication
interface. |
3. |
Major
Control Components |
| |
Major
equipment is normally furnished with controls
as part of the package including: |
| • |
Burner
Management (NFPA required compliance) if supplemental
firing |
| • |
Gas
turbine and generator control |
| • |
Gas
Compressor (if required) |
| • |
Chiller |
HRSG,
Chiller, and BOP equipment controls |
| • |
Feed
water control to HRSG |
| • |
Management
of Diverter (if equipped) |
| • |
Supplemental
firing rate of HRSG (if burner equipped) |
| • |
Chiller
start/stop operation |
| • |
Chilled
water set point and load management |
| • |
Operation
of various pumps, makeup water systems, cooling
towers and other plant auxiliaries |
| • |
Plant
water chemistry measurement and control for cooling
tower and boiler system |
|
4. |
Remote
Monitoring |
5. |
Safety |
| |
| • |
Gas
Leak Detection Interrupt |
| • |
Start
building exhaust fans |
| • |
Provide
visual and audible alarms in building and at every
entrance |
|
6. |
Emission
and Environmental Monitoring |
|
| • |
CEM
as required by local or federal regulation.
Blowdown monitoring as required by local authority |
| • |
Blowdown
monitoring as required by local authority |
|
Back
To Top
Mechanical
Interconnections
| Mechanical
interfaces represent the bulk of the connections required
with turbine generator-based CHP systems. |
1. |
Natural
Gas |
|
Turbine
generators may operate on a variety of fuels: natural
gas, diesel or distillate oil, landfill or waste gas,
hybrid fuels, bio-fuel and high hydrocarbon fuel, are
among the most prevalent. |
|
1.1 |
Natural
Gas Specification |
| |
|
Many
CHP equipment manufactures provide a natural gas specification.
Performance may only be guaranteed if the specification
criteria are met. A gas analysis, usually obtained from
the natural gas utility, should be compared with the specification.
Additional equipment may be required to meet the utility’s
gas specification requirements. For example, a pressure
reducing station may be required to lower the gas pressure,
and heaters may be required to remove any non-condensable
particulate formed by this temperature drop and pressure
reduction |
| |
1.2 |
Gas
Compressors |
| |
|
Turbine
generator sets in the size range between 2 MW and 5 MW
typically require medium to high pressure gas (175 psi
to 325 psi) for operation. If proper gas pressure is not
available locally, a new high pressure line(s) may be
run from the gas utility. If this new gas line is cost
prohibitive, gas compressor(s) may be installed. Redundant
gas compressors and associated maintenance may be a costly
item, and should be evaluated on a site by site basis.
Multiple smaller gas turbine generator units which require
lower gas pressure may indeed be a better investment in
place of a new high pressure gas line or installing several
gas compressors. |
| |
1.3 |
Leak
Detection |
| |
|
Many
regulations, and good engineering practice, dictate that
natural gas leak detection be utilized when working with
high pressure gas systems. The leak detection system is
typically tied in with the plant control system, and will
automatically close the gas shut off valve in the event
that gas is detected. |
2. |
Diesel |
|
Diesel
and natural gas are by far the two most common fuels for
turbine generator CHP systems. Higher emissions and diesel
fuel cost usually prescribe natural gas as the fuel of
choice, but diesel burning capability may allow a facility
to leverage natural gas by buying from cheaper interruptible
tariffs. A second fuel capability will further provide
a solid back up fuel option incase a primary fuel is unavailable
or not economical. On site diesel fuel will require storage
tanks and any associated air/groundwater permitting. Secondary
containment will been to be addressed if required, as
well as the filing of any storm water pollution prevention
plan (SWP3) or spill prevention control and countermeasure
(SPCC) plans required by the regulator. Proper siting
is required for filling access by the diesel supplier.
Many turbine manufactures require an additional air compressor
to start a turbine on diesel. |
3. |
Chilled
/ Hot Water |
|
The
Broad USA unit converts hot gas exhaust from the gas turbine
into chilled or hot water. The interface to these systems
is typically a simple welded pipe connection. Hot tapping
may be utilized to avoid interruption of an existing system.
Additional control devices may be required if the new
CHP equipment works alongside existing chilling and/or
heating equipment. Chilled water systems will require
cooling water systems, which include cooling towers, city
water makeup, chemical treatment, blowdown, and freeze
protection. Hot water systems also have simple chemical
treatment. |
4. |
Steam |
|
CHP
equipment can often be integrated into an existing plant
with no additional requirement for steam auxiliaries.
Typical steam auxiliaries include condensate storage tanks,
condensate return pumps, water treatment equipment, deaerator,
blowdown and boiler feed pumps. If the CHP steam production
is similar to the existing plant’s steam production,
most of these auxiliaries may continue to be used. |
5. |
City
Water |
| |
Existing
heating plants probably use city water for makeup, and
treat the water with additional chemicals and equipment
accordingly. Turbine compressor blades foul after a certain
operational time, and require washing at regular intervals.
Washing may be on-line or offline, and requires a specific
water quality. Additional equipment may be required to
remove impurities and/or hardness of the city water supply,
and additional pumps may be required to increase water
pressure. |
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Siting
| 1. |
Permiting |
| |
Permits
for construction and operation of a CHP facility will
be required from federal, state, and local jurisdictions.
The following list (adopted from Spiewak) represents a
good starting point. |
| |
1.1 |
Federal |
| |
|
| • |
Federal
Aviation Administration Notification of Proposed
Construction |
| • |
NEPA
Certification |
| • |
U.S.
Army Corps of Engineers Section 10 Permit |
| • |
U.S.
Army Corps of Engineers Section 404 Permit |
| • |
U.S.
EPA NPDES Permit |
|
| |
1.2 |
State |
| |
|
| • |
Coastal
zone management certificate of consistency |
| • |
Cross
connection permit |
| • |
Environmental
impact statement |
| • |
Floodplain
development |
| • |
Gas
pipeline approval |
| • |
Groundwater
discharge permit |
| • |
Historical
Commission approval |
| • |
Industrial
user discharge permit |
| • |
Oil
storage tank construction permit |
| • |
PSD/air
plans review |
| • |
Sewer
extension/connection permit |
| • |
Siting
approval |
| • |
Solid
waste facility operating permit |
| • |
Solid
waste facility site assignment |
| • |
Surface
water discharge permit (with NPDES) |
| • |
Water
quality certification |
| • |
Water
withdrawal permit |
| • |
Wetlands
approval of local order of conditions |
|
| |
1.3 |
Local |
| |
|
| • |
Board
of Health |
| • |
Building
Inspector |
| • |
Conservation
Commission |
| • |
Department
of Public Works |
| • |
Fire
Department |
| • |
Historical
Society |
| • |
Planning
Board |
| • |
Water
Department/Sewer Commission |
| • |
Zoning
Board of Appeals |
|
| 2. |
Utility
Tie-ins |
| |
Ideally,
the the new CHP plant is close to the existing powerhouse,
switchgear, site distribution systems, and fuel supply
lines. This allows for easy integration with existing
utilities. The turbine/generator set of the Reference
Designs can be located next to the existing power plant
in a weatherized enclosure. |
| 3. |
Interior
Siting |
| |
If
the new CHP plant is integrated into an existing
plant structure, the older structure may need
to undergo a number of modifications including |
| • |
Overcoming
space limitations that may limit access to all components
of the CHP plant |
| • |
Upgrade
of the existing chilled or hot water or steam piping |
| • |
Upgrade
of the existing power lines |
| • |
Structural
upgrades to accommodate the weight of the new equipment |
| • |
Upgrade
of the existing ventilation system |
|
| |
Independently
if the CHP plant is located in an existing or
a new building, at a minimum consideration should
be given to the following. |
| • |
Access
to equipment |
| • |
Fire
code requirements |
| • |
Maintenance
access |
| • |
Structural
Consideration |
| • |
Ventilation |
| • |
Vibration
isolation |
|
| 4. |
Exterior
Siting |
| |
Considerations
with regard to the exterior siting of an CHP system
are very similar to that of the interior siting.
Of particular concern are: |
| • |
Access
to equipment |
| • |
Aesthetics
of the overall installation |
| • |
Maintenance
access |
| • |
Noise |
| • |
Soil
&Structural Consideration |
|
| 5. |
Noise
|
| |
By
their very design, combustion turbines are relatively
quiet and vibration free. In general, they produce
noise at high frequencies that easily can be attenuated.
Following points may be considered to control
the noise emissions of the CHP plant. |
| • |
Attenuated
turbine enclosure |
| • |
Gas
compressor noise suppression |
| • |
Gas
turbine exhaust stack muffler |
| • |
Intake
air attenuation |
| • |
Plant
wall soundproffing |
| • |
Sound
proof roll up doors and windows |
| • |
Turbine
enclosure ventilation |
|
Back
To Top
Utility
Loads
| Utility
loads are patterns of usage of electrical and thermal
energy requirements by the facility. They vary with
the time of day and the seasons. The sucess of a CHP
installation depends on the ability of the CHP plant
to have all of its electrical and thermal
output be continuously used by the facility, i.e., the
CHP plant energy output profile should closely match
the utility loads of the facility.
The
CHP system is commonly used to baseload a facility’s
thermal and electrical utility loads; small portions
of utilities continue to be purchased through existing
means. CHP may also be used to peak shave a facility’s
electrical load; however total cycle performance decreases
as heat recovery may not be fully utilized. |
| 1. |
Electrical
Demand/Usage |
| |
A
large portion of the cost-of-energy savings recovered
by a CHP project is produced by generating electric power
with the CHP equipment and offsetting electrical power
normally purchased from the local utility. In some instances
a CHP facility may be designed to also sell excess power
to the utility grid. This, however, is rare in CHP facilities
of this size. |
| |
1.1 |
Site
Load Control |
| |
|
Site
load control is normally accomplished by operating the
generator equipment in parallel with the utility grid
and the existing site distribution system. |
| |
1.2 |
Electrical
Generator Sizing |
| |
|
The
CHP electrical generator is normally sized to produce
approximately enough electrical power to offset the minimum
electrical demand that the facility consumes. A major
focus on the initial CHP study is to determine the minimum
electrical loading. This is often difficult to determine
since most facilities record the maximum electrical demand
and not the minimum. If the CHP electrical generation
equipment is too large the facility will export power
to the utility during minimum demand times. For the normal
CHP facility of this magnitude this is usually not desirable. |
| |
1.3 |
Utility
Buy-Back |
| |
|
CHP
facilities can sell power to the utility. This may be
to dispose of large amounts of excess power produced at
low usage times or may be negotiated so that large variations
in the steam distribution system can be managed without
loosing the turbine. The reason that selling power to
the utility is usually not feasible is due to the discrepancy
between the utilities sell price and their purchase price.
Normally what utilities are willing to pay for power will
not offset the cost of operation for the CHP equipment. |
| 2. |
Utility
Tariffs |
| |
Charges
levied against the CHP are as varied as the number of
utilities involved. To date there is no standard formula
for determining the cost of utility charges so each case
must be analyzed on its own merits. Charges from the utilities
that may be anticipated are outlined below. |
| |
2.1 |
Cost
of Utility Interconnection |
| |
|
Most
utilities will expect the CHP budget to pay for the cost
of inter connect. This usually will encompass the following. |
| |
|
2.1.1 |
Interconnect
Study |
| |
|
|
The
first step in utility negotiations is to obtain a copy
of their interconnect requirements. Some utilities require
that an interconnect study be performed to set forth the
specifications for the specific interconnect site. The
cost of this study will be paid for by the CHP budget. |
| |
|
2.1.2 |
Substation
Cost |
| |
|
|
If
the site substation is owned by the utility, it is commonly
expected that the substation be purchased from the utility. |
| |
|
2.1.3 |
Metering
Cost |
| |
|
|
Since
the average CHP site is not metered to accommodate cogeneration
most utility interconnect agreements will include this
charge. |
| |
|
2.1.4 |
System
Control and Data Acquisition (SCADA) Installation |
| |
|
|
Some
utilities require the installation of SCADA equipment.
SCADA will definitely be required in those facilities
selling power to the utility. If required, this installation
will be paid by the CHP budget. |
| |
|
2.1.5 |
Protective
Relaying Improvements |
| |
|
|
Cost
of protective relaying improvements required to protect
the cogeneration equipment will be paid by the CHP budget. |
| |
|
2.1.6 |
Standby
Charges |
| |
|
|
Utilities
will usually have some method or recouping the cost of
standby power. Standby power is the power that is required
when the CHP facility is down for maintenance or for the
excess power purchased from the utility above that produced
by the CHP. This tariff can be a negotiated firm demand
with severe penalties for exceeding the negotiated amount,
or it could also be a ratcheting demand where the facility
pays a demand charge based on the largest demand set over
the past twelve months. This charge is also different
for each utility. |
| |
2.2 |
Other
Charges |
| |
|
Other
charges to be expected is a service charge for each metering
point, a cost of energy charge, a cost of demand charge |
| |
|
2.2.1 |
Demand
Charges |
| |
|
|
Demand
charges are based on the largest demand measured in kilowatts
or kilovolt-amperes required by the site during a fifteen-minute,
or thirty-minute period of time depending on the utility. |
| |
|
2.2.2 |
Power
Factor |
| |
|
|
A
penalty for poor power factor or excess reactive power
purchased is usually levied against the facility. |
| |
|
2.2.3 |
Energy
Charge |
| |
|
|
A
cost of energy charge for each kilowatt-hour consumed
by the site will also be levied. |
| |
|
2.2.4 |
Time
of Day / Time of Year Charges |
| |
|
|
These
rates may differ for times of the year or even times of
the day in which the energy is purchased. These billing
rated are usually on peak and off peak with the on peak
being the more expensive. For this reason maintenance
on the CHP should be scheduled during off peak hours.
Off peak hours are determined from the utility rate structure. |
| 3. |
Thermal
Demand/Usage |
| |
Turbine
exhaust energy is converted or extracted through heat
recovery equipment. |
| |
3.1 |
Steam |
| |
|
Steam
is probably the most common method of thermal energy produced
by a CHP system. A heat recovery boiler is typically used
to generate steam with the turbine exhaust. Supplemental
gas may be consumed in a duct burner to increase the amount
of steam generated. The upper limit of steam production
is related to the amount of free oxygen (O2) in the turbine
exhaust stream. |
| |
3.2 |
Chilled/Hot
Water |
| |
|
Chilled
water typically peaks in the warmer summer months, and
hot water (if used primarily for heating) peaks in the
winter months. A portion of hot water may be used year
round for domestic purposes. The Broad USA unit is able
to produce chilled water and hot water simultaneously,
recovering energy in the turbine exhaust continuously. |
| |
3.3 |
Process
Heating |
| |
|
There
are a variety of process heating uses: drying operations,
kilns, stripping, direct heating, etc. The exhaust ductwork
may be directly tied into such a system, but typically
requires a healthy bit of additional engineering effort.
Care must be taken to not exceed the turbine manufacturer's
exhaust static pressure limitation. |
| |
3.4 |
Desiccant
Dehumdification |
| |
|
Recovered
heat can also be used to regenerate an active desiccant
systems. This may particularly be beneficial in facilities
that require tight humidity control, are located in a
hot and humid climate, or require high outdoor air intakes.
Pretreating the outdoor air with actively regenerated
desiccant systems can also reduce the required chiller
capacity. |
Back
To Top
Waste
Several
waste products are generated from a CHP facility, some of
which require treatment before disposal through sanitary or
storm sewers. Most facilities choose to use an off site disposal
service in place of installing, operating, and maintaining
waste treatment equipment.
Typical
sources of waste requiring disposal may include:
- Blowdown
coolers
- Gas
compressors
- Additives
and chemicals used for treatment
- Lube
oil
Back
To Top
Additional
Information Resources
| Codes
& Standards |
| |
Building
Codes |
| |
|
First
Source maintains detailed information on building
codes for all 50 states, major cities, and some counties.
The site offfers information on codes and amendments as
well as contact information for up to 17 authorities having
jurisdiction (AHJs) in each market. |
| |
|
The
International
Code Council has developed a single set of comprehensive
and coordinated national model construction codes. The
ICC website offers information on which states and jurisdictions
have adopted one or all of the international model codes.
|
| |
Mechanical
Codes & Standards |
| |
|
ANSI
- American National Standards Institute |
| |
|
ASHRAE
- American Society of Heating, Refrigerating and Air-Conditioning
Engineers |
| |
|
ASME
- American Society of Mechanical Engineers |
| |
|
ASTM |
| |
|
UL
- Underwriters Laboratories |
| |
Electrical
Codes & Standards |
| |
|
IEEE |
| |
|
Pacific
Gas & Electric -- This site provides information
on Rule 21 generators |
| Online
Journals |
| |
|
Cogeneration
and Competitive Power Journal |
| |
|
Energy
Engineering |
| Publications |
| |
|
Alderfer,
B.; Eldridge, M., Starrs, T., 2000. Making connections:
Case studies of interconnection barriers and their impact
on distributed power projects, National Renewable
Energy Laboratory Report NREL/SR-200-28053. |
| |
|
American
Society of Heating, Refrigerating and Air-Conditioning
Engineers, 2003. Handbook - HVAC Applications. |
| |
|
American
Society of Heating, Refrigerating and Air-Conditioning
Engineers, 2000. Handbook - HVAC Systems and Equipment. |
| |
|
American
Society of Heating, Refrigerating and Air-Conditioning
Engineers, 2003. Practical Guide to Noise and Vibration
Control for HVAC Systems |
| |
|
Andrepont,
J.S., 2001. Combustion Turbine Inlet Air Cooling (CTIAC):
Benefits, Technology Options, and Applications for District
Energy, Energy Engineering, Vol. 98, No. 3, pp52-69. |
| |
|
Arthur
D. Little, 1999. Distributed Generation: System Interfaces. |
| |
|
Atkins,
R.S., 2002. Environmental Permitting for Cogeneration
and Merchant Power Plants, Cogeneration and Competitive
Power Journal, Vol. 17, No. 1 (Winter 2001-2002), pp 54-70 |
| |
|
Bloomquist,
R.G., F.S. Hazard, 2001. Integrating CHP into An Existing
District Energy System A Cogeneration Case Study,
Cogeneration and Competitive Power Journal, Vol. 16, No.1
(Winter 2000-2001), pp59-79. |
| |
|
Chalifoux,
A.T., B.L. Lynn, A.R. McNamee Jr., B.A. Deal, 1996. The
Model Energy Installation Program: Progress and Lessons
Learned, ASHRAE Transaction
Vol 102, Pt. 2. |
| |
|
Chambers,
A., B. Schnoor, S. Hamilton, 2001. Distributed Generation:
A Nontechnical Guide. Pennwell
Corp. |
| |
|
Czachorski,
M., W. Ryan, J. Kelly, 2002. Building Load Profiles and
Optimal CHP Systems, ASHRAE
Transaction Vol 108, Pt. 2. |
| |
|
ETSU
1999. Good practice guide 43: Introduction to large-scale
combined heat and power |
| |
|
Hamilton,
S. 2003. Microturbine Generator Handbook, Pennwell
Corp. |
| |
|
Harrell,
G., R. Jendrucko, 2003. Steam Turbine Versus Presuure
Reducing Valve Operation, Cogeneration and Competitive
Power Journal, Vol. 18, No. 2 (Spring 2003) pp25-36 |
| |
|
Lenssen,
N. 2000. A Critical Technology: Interconnecting Distributed
Generation to the Grid, Cogeneration and Competitive
Power Journal, Vol. 15, No.3 (Summer 2000) pp. 18-25 |
| |
|
Maratan,
A., P. Popovic, R. Radermacher, 2002. The Potential of
CHP Technology in Commercial Buildings— Characterizing
the CHP Demonstration Building, ASHRAE
Transaction Vol 108, Pt. 1. |
| |
|
Onsite
Sycom Energy Corporation, 2000. The
Market and Technical Potential for Combined Heat and Power
in the Commercial/Institutional Sector, (Revision
1, January 2000) (PDF 359 KB) |
| |
|
Orlando,
J.A., 1996. Cogeneration Design Guide, American
Society of Heating, Refrigerating and Air-Conditioning
Engineers, Inc. |
| |
|
Petchers,
N., 2002. Combined Heating, Cooling & Power Handbook:
Technologies & Applications, The
Fairmont Press Inc. |
| |
|
Spiewak,
S., L. Weiss, L, 1997 . Cogeneration & Small
Power & Production Manual, Fifth Edition, The
Fairmont Press Inc. |
| |
|
The
Chartered Institution of Building Service Engineers, 1999.
CISBE
Application Manual AM12, Small-scale combined heat
and power for buildings. |
| CHP
Information Sources |
| |
|
Combined
Heat and Power (CHP) Program -- The Department of
Energy's Office of Energy Efficiency and Renewable Energy
is working on a number of fronts to support increased
use of CHP technologies. This site provides information
about the CHP Initiative, BCHP Initiative, Combustion
Program, Steam Challenge Program, and the Federal Energy
Management Program. |
| |
|
DOE
BCHP Initiative -- The objective of this site is to
provide you with information on CHP systems to facilitate
your decisions relating to these systems. |
| |
|
EPA's
CHP Partnership -- The CHP Partnership is a voluntary
program that seeks to reduce the environmental impact
of power generation by fostering the use of CHP. The Partnership
works closely with the CHP industry, state and local governments,
and other stakeholders to develop tools and services to
support the development of new projects and promote their
energy, environmental, and economic benefits. |
| |
|
California
Distributed Energy Resources Guide -- The California
Distributed Energy Resources Guide is a public benefit
site containing a wealth of information regarding distributed
energy resources (DER). |
| |
|
Midwest
CHP Information Center -- The Midwest CHP Application
Center was established in March 2001 for the U.S. Department
of Energy (DOE) at the University of Illinois at Chicago
(UIC) Energy Resources Center (ERC). The Center is a partnership
between UIC/ERC and the Gas Technology Institute (GTI).
Its mission is to provide application assistance, technology
information, and educational support in the eight Midwest
states of Illinois, Indiana, Iowa, Michigan, Minnesota,
Missouri, Ohio, and Wisconsin. |
| |
|
The
Midwest Cogeneration Association (MCA) promotes a
greater public understanding of cogeneration, independent
power production, and distributed generation. In addition,
MCA works to improve general business conditions of the
industry. The non-profit organization provides pertinent
information for its members to conduct research, publish
reports, and hold various seminars and workshops with
the goal to advance the concept of cogeneration throughout
the Midwest |
| |
|
The
U.S. Combined Heat and Power Association (USCHPA)
brings together diverse market interests to promote the
growth of clean, efficient CHP in the United States. It
is a private, non-profit association, formed in 1999 to
promote the merits of CHP and achieve public policy support. |
| |
|
California
Alliance for Distributed Energy Resources (CADER)
is a voluntary collaborative committed to facilitating
the successful deployment of highly efficient and environmentally
responsible distributed energy resources into competitive
energy markets. |
| |
|
CHP
-- This site gives you information about combined heat
and power production (CHP) and district heating and
cooling (DHC). The website provides you with information
on combined heat and power (CHP) and district heating
and cooling (DHC)from a technical, market and political
point of view. The web site includes both general and
country specific information about CHP and DHC in Europe. |
| |
|
The
Combined Heat and Power Association (of Great Britain)
works to promote the wider use of combined heat and power
and community heating |
| |
|
Cogen
Europe is the European Trade Association for the promotion
of cogeneration. Its principal goal is to work towards
the wider use of cogeneration in Europe for a sustainable
energy future. |
| |
Honeywell
BCHP Project |
| |
Honeywell |
| |
|
Honeywell
T.E.A.M. Services (for the Federal Government)
This site contains a link to the Ft. Bragg BCHP project. |
| |
|
Honeywell Enterprise Building Integrator (EBI). This
site prodes information the EBI technology, a scaleable
system that pulls together all core building systems and
integrates information from many different enterprise
subsystems, including environmental controls. |
| |
BCHP
Team Members |
| |
|
Broad
USA -- Broad Air Conditioning is the world’s
largest manufacturer of two-stage absorbers, selling approximately
500,000 tons of absorption cooling annually. Broad USA
provided the absorption chiller for the project. |
| |
|
Chelsea
Group Ltd -- Chelsea Group. is a leading consultant
to the indoor environment industry headquartered in Itasca,
IL. With a specific focus on indoor air quality, Chelsea
Group, provides strategic, technical, and marketing consulting
to businesses that create products and provide services
used to create resilient, productive indoor environments
and to maximize asset value. |
| |
|
I.C.
Thomasson (ICT). ICT is a multidisciplinary engineering
and consulting firm established in 1942 in Nashville,
TN and currently has branch offices in Knoxville, TN,
Tampa, FL, and an affiliated office in Brookhaven, MS.
The company is licensed in 43 states and has completed
more than 12,000 projects valued in excess of $18 billion.
ICT provides engineering services to sports, medical,
commercial, industrial, institutional, and military facilities
throughout the United States and abroad. |
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|
