Transcript Boiler Efficiency and Combustion Control

Preferred Utilities Manufacturing Corp.
Burner
Management Systems
A Technical Discussion
Preferred Utilities Manufacturing Corp.
 Introduction
 Burner
Management System Objectives
 BMS Design Standards and Definitions
 BMS Logic
 BMS Strategies and Hardware

Types of Burner Management Systems
 BMS
Interface to SCADA Systems
 Summary
Introduction
Burner Management
Systems..
..a starting point.
Introduction
What is a BMS?
 A Burner
Management System is defined as
the following:

A Control System that is dedicated to boiler
safety, operator assistance in the starting and
stopping of fuel preparation and burning
equipment, and the prevention of mis-operation
of and damage to fuel preparation and fuel
burning equipment. 1
1. From NFPA 8501 “Standard for Single Burner Boiler Operation”
Burner Management Objectives
 Sequence
burner through safe start-up
 Insure a complete pre-purge of boiler
 Supervise safety limits during operation
 Supervise the flame presence during
operation
 Sequence a safe shutdown at end of cycle
 Integrate with combustion control system
for proper fuel and air flows
BMS Design Standards

Each Burner Management System should be
designed in accordance with the below listed
guidelines to control and monitor all sequences of
the start-up and shutdown of the burner




National Fire Protection Association (NFPA 8501
/8502 or others)
Industrial Risk Insurers (IRI)
Factory Mutual loss prevention guidelines
Each burner management system should be
designed to accomplish a safety shutdown in the
event of an unsafe condition. (FAIL SAFE)
BMS Design Standards
 U.S.
National Fire Protection Association
(NFPA)

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
Governs safety system design on virtually all boilers
(regardless of the process to be used to combust the
fuel)
Requires the separation of the Burner Management
System from any other control system
Requires the use of a hardwired backup tripping scheme
for microprocessor based systems
Requires that a single failure NOT prevent an
appropriate shutdown
Factory Mutual loss prevention guidelines.
NFPA 8501
 NFPA 8501
Standard for Single Burner
Boiler Operation



Single Burner Boilers with fuel input greater than 12.5
mBTU/Hr (Approx. 250 BHP)
Single Fuel or Combination of Fuels (Common being
Natural Gas / No.2 Oil / No. 6 Oil)
Simultaneous Firing
NFPA 8502
 NFPA 8502
Standard for Prevention of
Furnace Explosions / Implosions in Multiple
Burner Boilers



Multiple Burner Boilers with fuel input greater than
12.5 mBTU/Hr
Single Fuel or Combination of Fuels including
Pulverized Coal
Emphasis on implosion protection (larger boilers with
induced draft systems)
BMS Definitions
 Furnace


Explosions
“Ignition of accumulated combustible mixture within
the confined space of a furnace or associated boiler
passes, ducts, and fans that convey gases of combustion
to the stack”1
Magnitude and intensity of explosion depends on
relative quantity of combustibles and the proportion of
air at the time of ignition
1. From NFPA 8502 “Prevention of Furnace Explosions / Implosions in Multiple Burner Boilers”
BMS Definitions
 Furnace
Explosions can occur with any or a
combination of the following:1

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Momentary loss of flame followed by delayed reignition
Fuel leakage into an idle furnace ignited by source of
ignition (such as a welding spark)
Repeated Light-off attempts without proper purging
Loss of Flame on one Burner while others are in
operation
Complete Furnace Flame-out followed by an attempt to
light a burner
1. From NFPA 8502 “Prevention of Furnace Explosions / Implosions in Multiple Burner Boilers”
BMS Definitions
 Furnace


Implosions
More common in large Utility Boilers
Caused by any of the following:
» Malfunction of equipment regulating boiler gas flow
resulting in furnace exposure to excessive induced
draft fan head capability
» Rapid decay for furnace gas temperature and
pressure due to furnace trip
1. From NFPA 8502 “Prevention of Furnace Explosions / Implosions in Multiple Burner Boilers”
BMS Basic Definitions
 Common Terminology

Supervised Manual
» Manual Burner Lightoff with Interlocks

Automatic Recycling (Single Burner Only)
» Automatic Burner Start and Stop based on preset
operating range (ie.. Drum pressure)

Automatic Non Recycling (Single Burner Only)
» Automatic Burner Start and Stop based on Manual
command to start.
Types of Flame Scanners
 Infrared


(IR) Detectors
Single Burner Applications
More Suitable with Oil Burning Flames
 Ultra-Violet


Multiple Burner Applications
More Suitable for Gas Burners and
Combination Gas / Oil Burners
 Self

(UV) Detectors
Check Scanners
Flame Signal is interrupted at set intervals to
verify proper operation of scanner
Single Burner BMS Inputs
Low Low Drum Level
(D)
High Steam Pressure
(D)
Purge Purge Air Flow
Minimum Air Flow
Flame / No Flame
Li m i t s M ade
Hol d t o Pur ge
S C R L
O
BURNER
FF
R E S E T M
F UEL
OGNA S
O
(D)
D E
SELECT
O
I L
FD
HAND
F AN
O FF
AUT O
Fuel Oil Temp Low
(D)
Fuel Oil Temp High
(D)
Fuel Oil Press Low
(D)
Fuel Oil Flow (A)
Atomizing Medium Flow > Min
Common Alarm Output
(D)
(D)
Atomizing
Medium
Press Low
(D)
(D)
AE
TE
(D)
Remote Annunciator
(By Others)
FEEDWATER
PSH
STEAM
PSL
PT
PSH
FT
IGNITER
GAS
Safety Shut Off
& Vent Valves
LS LL
LS LL
Fuel
Gas
Press
Low
Fuel
Gas
Press
High
(D)
(D)
FT
PSL
ATOMIZING
MEDIUM
FT
GAS
PSL
PSL
OIL
PSL
TSH
TSL
FS
Safety Shut Off
Valves
Control
Valve
Control Valve &
Shut Off Valve
(D) - Descrete Signal Used By Flame Safeguard System
PSH
Safety Shut Off &
Vent Valves
Control
Valve
BMS Logic
 Burner
Management Systems can be broken
down into “Interlock Groups”
 Typical BMS Interlock Groups:

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Boiler Purge
Igniter Header Valve Management
Main Fuel Header Valve Management
MFT (Master Fuel Trip) Logic
Purge Interlocks
BOILER TRIPPED
AND
PURGE / RESET PB
START-UP
TIMER
START FD FAN
PERMISSIVES SATISFIED:
- MAIN FUEL VALVES CLOSED
- NO FLAME PRESENT
- FD FAN RUNNING
- MINIMUM AIR FLOW SWITCH MADE
- WATER LEVEL SATISFACTORY
- ATOMIZING MEDIUM ON
- FUEL SUPPLY PRESSURE NOT LOW
AND
ENERGIZE FUEL RELAY
NOT
AND
PURGE SIGNAL TO CCS
PURGE AIR
FLOW SWITCH
MADE
AND
FD DAMPER IN
FULL OPEN
POSITION
PURGE TIMER SET
PURGE COMPLETE
YES
REMOVE PURGE TO CCS
NO
SYSTEM TRIP
Igniter Interlocks
PURGE COMPLETE
AIR DAMPER IN LOW FIRE
POSITION
AND
FUEL VALVE IN LOW FIRE
POSITION
ENERGIZE IGNITER AND
IGNITER HEADER VALVES
10 SECOND DELAY
10 SEC PILOT TRIAL
FOR IGNITION
TIMER COMPLETE
FLAME
PROVEN
NOT
AND
SYSTEM TRIP
PERMIT FOR MAIN
FLAME
Main Flame Interlocks
IGNITER TIMER
COMPLETE
FLAME
PROVEN
AND
ENERGIZE MAIN
FUEL VALVES
10 SEC MAIN FLAME
TRIAL
TIMER COMPLETE
NOT
AND
DE-ENERGIZE
IGNITION
COMPONENTS
RELEASE TO
MODULATE TO CCS
SYSTEM TRIP
Single Burner Main Fuel Trip
FOR OIL:
FOR GAS:
- LOWFUEL PRESSURE
- LOW TEMPERATURE (HEATED OILS)
- LOSS OF COMBUSTION AIR
- LOSS OF FLAME OR FAIL TO ESTABLISH
- LOSS OF CONTROL SYSTEMENERGY
- POWER FAILURE
- LOWWATER LEVEL (AUXLEVEL CONTACT)
- LOSS OF ATOMIZING MEDIUM
- EXCESSIVE STEAMDRUMPRESSURE
- HIGH OIL TEMPERATURE (HEATED OILS)
- LOW FUEL GAS PRESSURE
- HIGH GAS PRESSURE
- LOSS OF COMBUSTION AIR
- LOSS OF FLAME OR FAIL TO ESTABLISH
- LOSS OF CONTROL SYSTEMENERGY
- POWER FAILURE
- LOWWATER LEVEL (AUXLEVEL CONTACT)
- EXCESSIVE STEAMDRUMPRESSURE
OR
OR
TRIP BOILER
TRIP IGNITER,
IGNITER VALVES,
OPEN IGNITER
VENT
TRIP MAIN FUEL
VALVES, OPEN
VENT VALVE
(GAS ONLY)
FUEL CONTROL
VALVE TO
CLOSED
POSITION
TRIP MFT RELAY
BMS System Types
 Early


Burner Management Systems
Hardwired Systems
Solid State Systems
 Microprocessor

Fireye E110 / Honeywell 7800 series with fixed
Logic.
 PLC


Based Systems
Based Systems
Programmable Logic Controller (PLC) Based
Powerful, versatile, expandable, more reliable.
Early Burner Management Systems
 Hardwired
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Relay and Timer Driven. Found on older
installations
Typical of Late 50’s, 60’s
 Solid
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Systems
State Systems
Solid State Processors and Relays
Found on Systems provided in the 70’s and 80’s
Proprietary Hardware (ie.. Forney and Peabody)
Spare Parts are extremely hard to find.
MicroProcessor Based Systems
 Microprocessor
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Based System providing:
Burner Sequencing
Ignition
Flame Monitoring
 Fixed
Program with Limited Configuration
Changes
 Components Selected Based on Requirements

Programmers, Flame Amplifiers, Message Displays
Fireye™ BMS Layout
AMPLIFIER
EP PROGRAMMER
AUTOMATIC PRIMARY SAFETY CONTROL
FIELD WIRING
FLAME
SCANNER
FIELD WIRING
MicroProcessor Capabilities
 Simple,
Cost Effective
 Features

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Selectable Flame Amplifiers / Scanners
Remote Display
Remote Data Communications via Modbus Port
Modernization kits are available to integrate with older
systems
Spare Parts Normally Readily Available
When These Systems are Used
 “Simple”
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Boiler Installations
Packaged Firetube / Watertube Boilers (Steam /
Hot Water)
Single Burner
One Fuel at a Time
No Flue Gas Re-Circulation
Upgrades from Previous MicroProcessor Based
Systems
PLC Based Burner Management Systems

PLC Based Features
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NFPA 8501, 8502
Watchdog timer
UL 508 Certification
Redundant Scanners
 Logic+ Message Center
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Shows program status
Displays alarms
Prompts operator
PLC System Basic Design Features

Each PLC based burner management system should
incorporate a number of design techniques which
help detect and act upon unsafe failure modes which
can occur in any microprocessor based system.
These design features include the following:
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Critical Input Checking
Critical output channel monitoring
Electro-mechanical Master Fuel Trip (MFT) Relay
Redundant Watchdog Timers
Low Water Cut-out Monitoring During Blow Down
PLC Based System Capabilities
 Provision



for Multiple Fuel Firing
Capped gas input during curtailment
Changeover from gas to oil at any load
Simultaneous firing of waste and fossil fuels
 Redundant
Scanners, change scanner with fuel
 Single or Multiple Burner Applications
 Integration of BMS with SCADA
PLC Based Operator Interfaces
 Features

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Clear Written Messages to indicate status, required
operator interaction, trip/alarm indication
High Visibility through two lines of display
Messages reduce time consuming troubleshooting
Prioritizes Messages
» First Out Alarms
» Warning / Alarm Messages
» Status Messages / Prompts Operator
PLC System Layout (Typical)
Door Mounted Lights / Pushbuttons
Logic+ Message
Display
SW ITCH
PLC CPU
I/O
I/O
I/O
SILENCE
LIGHT
I/O
COMBUSTION
CONTROL SYSTEM
FLAME AMPLIFIER
(SINGLE /
REDUNDANT)
I/O EXPANSION
I/O
FIELD DEVICES
Benefits of PLC Based Systems
 Flexibility

Programming Software allows changes to
system
 Choice

of PLCs
GE / Modicon / Allen Bradley / Koyo
 Choice

/ Reliability
of Flame Scanners
PPC / Fireye / Honeywell / Iris / Coen
 Application
Specific
 Quantity of Burners / Fuels is not restricted
When to Use PLC Based Systems
 “Complex”

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Boiler Installations
Larger Packaged Units / Field Erected Units
Multiple Burners
Multiple Fuels, On-line Fuel Changeovers
Flue Gas Re-Circulation
Replace Existing Relay Logic Systems
Requirement to maintain consistent control
platform (spare parts, etc..)
BMS SCADA Interface
 BMS
Systems can be integrated into a
SCADA System
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Allows Remote Monitoring of Flame Status
Allows Remote Control of BMS
Events (ie.. Burner trip) can be routed to
Historical Portion of SCADA for fault
evaluation
Burner Operation can be trended over time
BMS SCADA Interface
 Interface
Methods:
SCADA PC
MODBUS
COMMUNICATION
PROTOCOL
MODBUS
COMMUNICATION
PROTOCOL
Communication
Interface
(If Necessary)
PLC CPU
I/O
I/O
I/O
I/O
BMS LOGIC+ SYSTEM
FIREYE E110 SYSTEM
BMS SCADA Interface
Summary
 Benefits Associated
with New Burner
Management Systems



Help Improve plant safety
Help qualify for reduced insurance cost
Reduce Startup and Down Time with
comprehensive alarming and diagnostics
Summary
 Review

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

of Topics Discussed
Objectives of Burner Management Systems
BMS Design Considerations
Basic BMS Logic
Types of Burner Management Systems
How BMS Systems can be integrated with
Plant Wide SCADA Systems
Preferred Utilities Manufacturing Corp
For further information, contact...
Preferred Utilities Manufacturing Corporation
31-35 South St. • Danbury • CT
T: (203) 743-6741 • F: (203) 798-7313
www.preferred-mfg.com