Burner Management Systems - A Technical Discussion

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

..a starting point.

Burner Management Systems..

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)

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

Momentary loss of flame followed by delayed re-ignition 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 burner1. 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 (UV) Detectors Multiple Burner Applications More Suitable for Gas Burners and Combination

Gas / Oil Burners Self Check Scanners

Flame Signal is interrupted at set intervals to verify proper operation of scanner

Single Burner BMS Inputs

OIL

GAS

STEAM

FEEDWATER

PSL

TSLTSH

PSL

High Steam Pressure (D)

Low Low Drum Level (D)

PSL PSH

PSL

ATOMIZINGMEDIUM

FuelGas

PressLow

(D)

FuelGas

PressHigh

(D)

FT

FT

AtomizingMediumPress Low (D)

Fuel Oil Flow (A)

Fuel Oil Temp High (D)

Fuel Oil Temp Low (D)

Atomizing Medium Flow > Min (D)

Fuel Oil Press Low (D)

PSH

PSL

FT

PSHPT

LSLL

LSLL

Purge Purge Air Flow (D)

Minimum Air Flow (D)

AE TE

(D) - Descrete Signal Used By Flame Safeguard System

Common Alarm Output (D)

Remote Annunciator(By Others)

Safety Shut Off &Vent Valves

Control Valve &Shut Off Valve

Safety Shut OffValves

ControlValve

ControlValve

Safety Shut Off& Vent Valves

IGNITERGAS

Flame / No Flame (D)

FS

F D F ANHAND OF F AUT O

Li m i t s M adeHol d t o Pur ge

S C R L M O D ER E S E T

F UEL SEL ECTGAS OIL

BURNEROF F ON

BMS Logic

Burner Management Systems can be broken down into “Interlock Groups”

Typical BMS Interlock Groups: Boiler Purge Igniter Header Valve Management Main Fuel Header Valve Management MFT (Master Fuel Trip) Logic

Purge InterlocksBOILER TRIPPED

A ND PURGE / RESET PB

S TA RT F D FA N

A ND

PERMISSIVES SATISFIED: - M A IN FUE L V A LV E S CLO S E D - NO FLA M E P RE S E NT - FD FA N RUNNING - M INIM UM A IR FLO W S W ITCH M A DE - W A TE R LE V E L S A TIS FA CTO RY - A TO M IZING M E DIUM O N - FUE L S UP P LY P RE S S URE NO T LO W

E NE RGIZE FUE L RE LA Y

P URGE S IGNA L TO C C S

NOT A ND

S TA RT-UPTIM E R

A NDP URGE A IR

FLOW S W ITC HM A D E

F D D A M P E R INFULL OP E NP OS ITION

P URGE TIM E R S E T

P URGE C OMP LE TE

RE MOV E P URGE TO C C S SYSTEM TRIP

Y E SNO

Igniter Interlocks

A ND

E NE RGIZE IGNITE R A NDIGNITE R HE A D E R V A LV E S

NOT

SYSTEM TRIP

P URGE C OMP LE TE

A IR D A M P E R IN LOW F IREP OS ITION

FUE L V A LV E IN LOW F IREP OS ITION

10 S E C OND D E LA Y

F LA MEP ROV E N

10 S E C P ILOT TRIA LF OR IGNITION

TIM E R C OMP LE TE

A ND

P E RMIT F OR M A INF LA ME

Main Flame Interlocks

A ND

NOT

SYSTEM TRIP

IGNITE R TIM E RC OM P LE TE

F LA MEP ROV E N

10 S E C M A IN F LA M ETRIA L

TIM E R C OM P LE TE

A ND

RE LE A S E TOM OD ULA TE TO C C S

E NE RGIZE M A INF UE L V A LV E S

D E -E NE RGIZEIGNITION

C OM P ONE NTS

Single Burner Main Fuel TripFOR OIL: - LOW FUEL PRESSURE - LOW TEMPERATURE (HEATED OILS) - LOSS OF COMBUSTION AIR - LOSS OF FLAME OR FAIL TO ESTABLISH - LOSS OF CONTROL SYSTEM ENERGY - POWER FAILURE - LOW WATER LEVEL (AUX LEVEL CONTACT) - LOSS OF ATOMIZING MEDIUM - EXCESSIVE STEAM DRUM PRESSURE - HIGH OIL TEMPERATURE (HEATED OILS)

TRIP BOILER

FOR GAS: - LOW FUEL GAS PRESSURE - HIGH GAS PRESSURE - LOSS OF COMBUSTION AIR - LOSS OF FLAME OR FAIL TO ESTABLISH - LOSS OF CONTROL SYSTEM ENERGY - POWER FAILURE - LOW WATER LEVEL (AUX LEVEL CONTACT) - EXCESSIVE STEAM DRUM PRESSURE

OR

OR

TRIP IGNITER,IGNITER VALVES,

OPEN IGNITERVENT

TRIP MAIN FUELVALVES, OPEN

VENT VALVE(GAS ONLY)

FUEL CONTROLVALVE TOCLOSED

POSITION

TRIP MFT RELAY

BMS System Types

Early Burner Management Systems Hardwired Systems Solid State Systems

Microprocessor Based Systems Fireye E110 / Honeywell 7800 series with fixed

Logic. PLC Based Systems

Programmable Logic Controller (PLC) Based Powerful, versatile, expandable, more reliable.

Early Burner Management Systems

Hardwired Systems Relay and Timer Driven. Found on older

installations Typical of Late 50’s, 60’s

Solid 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 Based System providing: Burner Sequencing Ignition Flame Monitoring

Fixed Program with Limited Configuration Changes

Components Selected Based on Requirements Programmers, Flame Amplifiers, Message Displays

FLA M ES C A N N E R

FIE LD W IR IN G

Fireye™ BMS Layout

A U T O M A T IC P R IM A R Y S A F E T Y C O N T R O L

A M P LIF IE RE P P R O G R A M M E R

FIE LD W IR IN G

MicroProcessor Capabilities

Simple, Cost Effective Features

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” 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 NFPA 8501, 8502 Watchdog timer UL 508 Certification

Redundant Scanners Logic+ Message Center

Shows program status Displays alarms Prompts operator

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:

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 System Basic Design Features

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 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)

Logic+ M essageD isplay

S W IT C H S IL E N C E L IG H T

D oor M ounted L ights / P ushbuttons

FLA M E A M P LIF IE R(S IN G LE /

R E D U N D A N T)

FIE LD D E V IC E S

PLC CPU I/O I/O I/O I/O

I/O EXPANSION I/O

C O M B U S TIO NC O N TR O L S Y S TE M

Benefits of PLC Based Systems

Flexibility / Reliability Programming Software allows changes to

system Choice of PLCs

GE / Modicon / Allen Bradley / Koyo Choice of Flame Scanners

PPC / Fireye / Honeywell / Iris / Coen Application Specific Quantity of Burners / Fuels is not restricted

When to Use PLC Based Systems

“Complex” 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 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:

PLC CPU I/O I/O I/O I/O

C om m unicationIn terface

(If N ecessary)

M O D B U SC O M M U N IC A TIO N

P R O TO C O L

M O D B U SC O M M U N IC A TIO N

P R O TO C O L

B M S LO G IC + S Y S TE M

S C A D A P C

FIR E Y E E 110 S Y S TE M

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 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 Corporation31-35 South St. • Danbury • CT

T: (203) 743-6741 • F: (203) 798-7313www.preferred-mfg.com