CleaverBrooks CBEX Elite Operation And Maintenance
CBEX Elite
Packaged Boiler
100-1200 HP
Operation and Maintenance
Manual Part No. 750-368 11/2013
!
WARNING
DANGER
DO NOT OPERATE, SERVICE, OR REPAIR THIS EQUIPMENT UNLESS YOU FULLY UNDERSTAND ALL
APPLICABLE SECTIONS OF THIS MANUAL.
DO NOT ALLOW OTHERS TO OPERA TE, SERVICE, OR REP AIR THIS EQUIPMENT UNLESS THEY FULL Y
UNDERSTAND ALL APPLICABLE SECTIONS OF THIS MANUAL.
FAILURE TO FOLLOW ALL APPLICABLE WARNINGS AND INSTRUCTIONS MAY RESULT IN SEVERE
PERSONAL INJURY OR DEATH.
TO: Owners, Operators and/or Maintenance Personnel
This operating manual presents information that will help to properly operate and care for the equipment. Study its contents carefully. The unit will provide good service and continued operation if proper operating and maintenance instructions are followed. No attempt should be made to operate the unit until the principles of operation and all of the
components are thoroughly understood. Failure to follow all applicable instructions and warnings may result in severe
personal injury or death.
It is the responsibility of the owner to train and advise not only his or her personnel, but the contractors' personnel who
are servicing, repairing or operating the equipment, in all safety aspects.
Cleaver-Brooks equipment is designed and engineered to give long life and excellent service on the job. The electrical
and mechanical devices supplied as part of the unit were chosen because of their known ability to perform; however,
proper operating techniques and maintenance procedures must be followed at all times. Although these components afford a high degree of protection and safety, operation of equipment is not to be considered free from all dangers and
hazards inherent in handling and firing of fuel.
Any "automatic" features included in the design do not relieve the attendant of any responsibility. Such features merely
alleviate certain repetitive chores, allowing more time for proper upkeep of the equipment.
It is solely the operator’s responsibility to properly operate and maintain the equipment. No amount of written instructions
can replace intelligent thinking and reasoning and this manual is not intended to relieve the operating personnel of the
responsibility for proper operation. On the other hand, a thorough understanding of this manual is required before attempting to operate, maintain, service, or repair this equipment.
Because of state, local, or other applicable codes, there are a variety of electric controls and safety devices which vary
considerably from one boiler to another. This manual contains information designed to show how a basic burner operates.
Operating controls will normally function for long periods of time and we have found that some operators become lax in
their daily or monthly testing, assuming that normal operation will continue indefinitely. Malfunctions of controls lead to
uneconomical operation and damage and, in most cases, these conditions can be traced directly to carelessness and
deficiencies in testing and maintenance.
It is recommended that a boiler room log or record be maintained. Recording of daily, weekly, monthly and yearly maintenance activities and recording of any unusual operation will serve as a valuable guide to any necessary investigation.
Most instances of major boiler damage are the result of operation with low water. We cannot emphasize too strongly the
need for the operator to periodically check the low water controls and to follow good maintenance and testing practices.
Cross-connecting piping to low water devices must be internally inspected periodically to guard against any stoppages
which could obstruct the free flow of water to the low water devices. Float bowls of these controls must be inspected
frequently to check for the presence of foreign substances that would impede float ball movement.
The waterside condition of the pressure vessel is of extreme importance. Waterside surfaces should be inspected frequently to check for the presence of any mud, sludge, scale or corrosion.
It is essential to obtain the services of a qualified water treating company or a water consultant to recommend the proper
boiler water treating practices.
The operation of this equipment must comply with all requirements or regulations of the owner ’s insurance company
and/or other authority having jurisdiction. In the event of any conflict or inconsistency between such requirements and
the warnings or instructions contained herein, please contact Cleaver-Brooks before proceeding.
CHAPTER 1 Basics 1-1
1.1 — Overview 1-1
1.2 — The Boiler 1-2
1.3 — Construction 1-3
1.4 — Steam Controls (all fuels) 1-3
1.5 — Hot Water Controls (all fuels) 1-6
1.6 — IFGR Components 1-7
1.7 — Fan/Motor Cassette 1-7
CONTENTS
CHAPTER 2
CHAPTER 3
Burner and Fuel System 2-1
2.1 — The Burner 2-1
2.2 — Front Head and Panel 2-2
2.3 — Gas System 2-3
2.4 — Oil System 2-5
2.5 — Controls for Combination Burners 2-6
2.6 — Combustion Air 2-6
2.7 — Automatic Ignition 2-7
2.8 — Atomizing Air 2-7
2.9 — Oil Fuel Flow 2-8
2.10 — Gas Fuel Flow 2-9
2.11 — Modulating Firing 2-9
2.12 — Ultra Low NOx Systems 2-10
Waterside Care 3-1
3.1 — Overview 3-1
3.2 — Water Requirements 3-1
3.3 — Water Treatment 3-5
3.4 — Cleaning 3-6
3.5 — Boil-Out of a New Unit 3-7
3.6 — Washing Out 3-9
3.7 — Blowdown: Steam Boiler 3-10
3.8 — Periodic Inspection 3-12
3.9 — Preparation for Extended Layup 3-13
CHAPTER 4 Sequence of Operation 4-1
4.1 — Overview 4-1
4.2 — Circuits and Interlocks 4-2
4.3 — Firing Rate Controls 4-3
4.4 — Sequence of Operation: Gas or Oil 4-3
4.5 — Flame Loss Sequence 4-5
CHAPTER 5
CHAPTER 6
Starting and Operating Instructions 5-1
5.1 — General Preparation for Startup: All Fuels 5-1
5.2 — Control Settings: Steam and Hot Water 5-2
5.3 — Gas Pilot 5-3
5.4 — Atomizing Air 5-3
5.5 — Firing Preparations for No. 2 Oil (Series 100-200) 5-4
5.6 — Firing Preparations for Gas (Series 200-700) 5-6
5.7 — Startup, Operating, and Shutdown: All Fuels 5-8
5.8 — Control Operational Checks 5-10
Adjustment Procedures 6-1
6.1 — Overview 6-1
6.2 — Burner Operating Controls: General 6-1
6.3 — Operating Limit Pressure Control 6-4
6.4 — High Limit Pressure Control 6-4
6.5 — Operating Limit Temperature Control: Hot Water 6-5
6.6 — High Limit Temperature Control: Hot Water 6-5
6.7 — Low Water Cutoff Devices: Steam and Hot Water 6-5
6.8 — Combustion Air Proving Switch 6-5
6.9 — Atomizing Air Proving Switch 6-6
6.10 — Gas Pilot Flame Adjustment 6-6
6.11 — Gas Pressure and Flow Information 6-8
6.12 — Adjusting Combustion 6-11
6.13 — Low Gas Pressure Switch 6-12
6.14 — High Gas Pressure Switch 6-12
6.15 — Burner Drawer Adjustment 6-13
6.16 — Oil Drawer Switch 6-13
CHAPTER 7
Troubleshooting 7-1
7.1 — Problem-Cause Suggestions 7-2
CHAPTER 8 Inspection and Maintenance 8-1
8.1 — Overview 8-1
8.2 — Fireside Cleaning 8-3
8.3 — Water Level Controls 8-3
8.4 — Water Gauge Glass 8-5
8.5 — Electrical Controls 8-5
8.6 — Flame Safety Control 8-7
8.7 — Oil Burner Maintenance 8-9
8.8 — Gas Burner Maintenance 8-11
8.9 — Motorized Gas Valve 8-12
8.10 — Solenoid Valves 8-12
8.11 — Air Control Damper 8-13
8.12 — Fan/Motor Cassette Removal 8-14
8.13 — IFGR Inspection and Adjustment 8-15
8.14 — Fan/Motor Cassette Installation 8-16
8.15 — Safety Valves 8-16
8.16 — Fuel Oil Metering Valve 8-17
8.17 — Air Pump and Lubricating System 8-19
8.18 — Refractory 8-24
8.19 — Front Door and Rear Access Plug 8-27
8.20 — Lubrication 8-28
8.21 — Combustion Adjustments 8-29
8.22 — EPA Compliance 8-29
CHAPTER 9
Parts 9-1
Arch Brick & Liner Tiles 9-2
Blower Cassette 9-3
Main Gas Train 9-7
Starter Gas Train 9-8
Pilot Gas Train 9-9
Actuator Assembly, Fuel Oil 9-10
Actuator Assembly, Air Damper 9-11
Actuator Assembly, IFGR Valve 9-11
Actuator Assembly, Gas Butterfly Valve 9-12
Pressure Controls 9-13
Water Column, LWCO 9-14
Auxiliary Low Water Cutoff 9-15
Blower Davit: 55” & 60” 9-16
Front Head Hinge: 55” & 60” 9-17
Front Davit Assembly 9-18
Front Head Assembly 9-19
Burner Installation 9-24
Fireside Gaskets 9-29
CHAPTER 1 Basics
1.1 — Overview
CBEX Elite boilers are available for steam or hot water (100-800 HP only) applications. Basic construction consists of a cylindrical vessel with horizontal tubes passing through and connected to the front and rear tube
sheets. The vessel contains the water and absorbs the energy generated from the flame.
The flame originates in the furnace. As the combustion gases travel down the furnace and through the various
firetube channels, heat from the flame and combustion gases is transferred to the water.
Transferred energy develops into the required steam or hot water. The primary purpose of the boiler is to supply
energy to the facility’s operations — for heat, manufacturing processes, laundry, kitchen, etc. The nature of the
facility’s operation will dictate whether a steam or hot water boiler should be used.
This manual covers CBEX Elite boilers ranging from 100 through 1200 boiler horsepower for the following fuels:
Series 100 Light Oil (No. 2)
Series 200 Light Oil (No. 2) or Gas
Series 700 Gas
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CBEX Elite 100-1200 HP
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Basics
The low emission option for the CBEX Elite line of Firetube Boilers reduces Nitrogen
Oxide (NOx) emissions, a major contributor to ozone pollution (smog). Carbon Monoxide
(CO) emissions also tend to be lower as increased turbulence caused by the addition of
the flue gases into the combustion air stream results in improved combustion.
The CBEX Elite Firetube Boiler line is designed to incorporate Induced Flue Gas Recirculation (IFGR) when firing either natural gas and/or light oil, and is compatible with both
hot water and steam systems.
The IFGR system mixes a portion of the relatively cool flue gas from the exit of the second-pass tubes with the incoming combustion air to reduce the furnace flame temperature, thereby reducing NOx emissions. In this approach, the combustion air fan handles
both the combustion air and the recirculated flue gases.
FIGURE 1-1. Induced Flue Gas Recirculation (IFGR)
The low emission design can affect the selection of the combustion air fan, motor, burner, and other components.
Several different system configurations are available, depending on the requirements for NOx emissions and the
fuels used. All systems use similar primary components, but may have different IFGR damper fan and motor
sizes.
The boiler and related equipment installation should conform to state and local codes governing such equipment.
Prior to installation, the proper authorities having jurisdiction are to be consulted, permits obtained, etc.
All CBEX Elite boilers in the series comply, when equipped with optional equipment, to Industrial Risk Insurers
(IRI), Factory Mutual (FM), or other insuring underwriters requirements.
1.2 — The Boiler
The CBEX Elite boiler is a packaged firetube boiler of welded steel construction and consists of a pressure vessel,
burner, burner controls, forced draft fan, damper, air pump, refractory, and appropriate boiler trim.
The horsepower rating of the boiler is indicated by the numbers following the fuel series. For example, CBEX
700-600 indicates a gas-fired 600 hp boiler.
The firetube construction provides some characteristics that differentiate it from other boiler types. Because of its
vessel size, the firetube boiler contains a large amount of water, allowing it to respond to load changes with minimum variation in steam pressure.
Firetube boilers are rated in boiler horsepower (BHP), which should not be confused with other horsepower measurements.
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CBEX Elite 100-1200 HP
1.3 — Construction
Hot water is commonly used in heating applications with boiler supplied water to the system at 180º F to 220º
F. The operating pressure for hot water heating systems usually is 30 psig to 125 psig.
Steam and hot water boilers are defined according to design pressure and operating pressure.
Design pressure is the maximum pressure used in the design of the boiler for the purpose of calculating the minimum permissible thickness or physical characteristics of the pressure vessel parts of the boiler. Typically, the
safety valves are set at or below design pressure.
Operating pressure is the pressure at which the boiler normally operates. The operating pressure usually is maintained at a suitable level below the setting of the pressure relieving valve(s) to prevent frequent valve opening
during normal operation.
The type of service that your boiler is required to provide has an important bearing on the amount of waterside
care it will require.
Feedwater equipment should be thoroughly checked before use. Be sure that all valves, piping, boiler feed
pumps, and receivers are installed in accordance with prevailing codes and practices.
The close observance of water requirements for both steam and hot water boilers is essential to boiler life and
length of service. Constant attention to water requirements will pay dividends in the form of longer life, less
downtime, and prevention of costly repairs.
Care taken in placing the pressure vessel into initial service is vital. The waterside of new boilers and new or
remodeled steam or hot water systems may contain oil, grease, or other foreign matter. A method of boiling out
the vessel to remove accumulations is described in Chapter 3.
1.3 — Construction
Steam boilers designed for 15 psig and hot water boilers designed for 250º F at 125 psi or less are constructed
in accordance with Section IV, Heating Boilers, of ASME Code.*
Steam boilers designed for operating pressures exceeding 15 psig are constructed in accordance with Section I,
Power Boilers, of the ASME Code. Hot water boilers designed for operating temperatures above 250º F or 125
psi are likewise built to Section I of the ASME Code.
*CBEX Elite steam boilers are high pressure steam only.
1.4 — Steam Controls (all fuels)
1.4.1 — Controls
1. Pressure Gauge: Indicates boiler internal pressure.
2. Operating Limit Pressure Control: Breaks a circuit to stop burner operation on a rise of boiler pressure at a
selected setting. It is adjusted to stop or start the burner at a preselected pressure setting.
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CBEX Elite 100-1200 HP
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Basics
3. High Limit Pressure Control: Breaks a circuit to stop burner operation on a rise of pressure above a selected
setting. It is adjusted to stop the burner at a preselected pressure above the operating limit control setting.
The high limit pressure control is normally equipped with a manual reset.
FIGURE 1-2. Steam Controls
1.4.2 — Low Water Cutoff
FIGURE 1-3. Low Water Cutoff
The style of Low Water Cutoff is determined by the design pressure of
the vessel or by customer preference. The CB Level Master (for operation and maintenance information, consult the Level Master manual
that accompanied the boiler) is used on all steam boilers 150 psig to
250 psig.
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CBEX Elite 100-1200 HP
1.4 — Steam Controls (all fuels)
1. Low Water Cutoff and Pump Control: Float-operated control responds to the water level in the boiler. It per-
forms two distinct functions:
•Stops firing of the burner if water level lowers below the safe operating point. Energizes the low-water light in
the control panel; also causes low-water alarm bell (optional equipment) to ring. Code requirements of some
models require a manual reset type of low water cutoff.
•Starts and stops the feedwater pump (if used) to maintain water at the proper operating level.
2. Water Gauge Glass Drain Valve: Provided to flush the gauge glass.
3. Vent Valve: Allows the boiler to be vented during filling and facilitates routine boiler inspection as required by
ASME Code.
4. Water Column Drain Valve: Provided so that the LWCO and its piping can be flushed regularly to assist in
maintaining cross-connecting piping and in keeping the float bowl clean and free of sediment. A similar drain
valve is furnished with auxiliary low water cutoff for the same purpose.
1.4.3 — Safety Valve(s)
Safety Valves: Prevent buildup over the design pressure of the pressure vessel. The size, rating, and number of
valves on a boiler is determined by the ASME Boiler Code. The safety valves and the discharge piping are to be
installed to conform to the ASME Code requirements. The installation of a valve is of primary importance to its
service life. A valve must be mounted in a vertical position so that discharge piping and code-required drains can
be properly piped to prevent buildup of back pressure and accumulation of foreign material around the valve seat
area. Apply a moderate amount of pipe compound to male threads and avoid over-tightening, which can distort
the seats. Use only flat-jawed wrenches on the flats provided. When installing a flange connected valve, use a
new gasket and draw the mounting bolts down evenly. Do not install or remove side outlet valves by using a pipe
or wrench in the outlet.
FIGURE 1-4. Safety Valve Piping and Safety Valves
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CBEX Elite 100-1200 HP
1-5
Only properly certified personnel such as the safety valve manufacturer ’s certified representative can adjust or repair
!
Warning
the boiler safety valves. Failure to follow these instructions could result in serious injury or death.
1.5 — Hot Water Controls (all fuels) 100-800 HP only
1.5.1 — Pressure and Temperature Gauges
1. Water Pressure Gauge: Indicates the boiler internal water pressure.
2. Water Temperature Gauge: Indicates the boiler water temperature.
Basics
1.5.2 — Controls
1. Modulating Temperature Control: Senses changing boiler water temperature and transmits the information to
change the burner firing rate when the manual-automatic switch is set on “automatic.”
2. High Limit Temperature Control: Breaks a circuit to stop burner operation on a rise of temperature at a
selected setting. It is adjusted to stop the burner at a preselected temperature above the operating control setting. The high limit temperature control normally is equipped with a manual reset.
3. Operating Limit Temperature Control: Breaks a circuit to stop burner operation on a rise of boiler temperature
at a selected setting. It is adjusted to stop or start the burner at a preselected operating temperature.
FIGURE 1-5. Temperature Gauge and Hot Water Controls
1.5.3 — Low Water Cutoff and ALWCO
1. Low Water Cutoff: Breaks the circuit to stop burner operation if the water level in the boiler drops below a
safe operating point, activating the low-water light and the optional alarm bell.
2. Auxiliary Low Water Cutoff (optional): Breaks the circuit to stop burner operation if the water level in the
boiler drops below the master low-water cutoff point.
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CBEX Elite 100-1200 HP
1.6 — IFGR Components
1.5.4 — Safety Valve(s)
Relieves the boiler of pressure higher than the design pressure or a lower pressure, if designated. Relief valves
and their discharge piping are to be installed to conform to ASME Code requirements.
1.6 — IFGR Components
1. Flue Gas Transfer Port, IFGR Damper, Flange Collar: The flue gas transfer port is a tube that allows the flue
gases to travel from the exit of the second-pass tubes to the entrance of the combustion air fan.
The IFGR damper controls the volume of flue gas induced into the combustion air stream. The damper is
located in the flue gas transfer port and is positioned by the control linkage.
2. Burner Drawer: The gas spudding pattern for the IFGR system may be different than that of a non-IFGR,
High-Turndown CB burner of the same horsepower (HP) model designation.
3. Combustion Air Inlet: The combustion air inlets are located at the top of the front door. Air enters from the
rear of the air inlet shrouds, which reduces the sound level and captures heat from the boiler and stack flue
outlet.
4. Front Door Insulation: If NOx emissions are below 60 ppm, the front door is insulated inside to control tem-
perature buildup. The insulation is held in place with wire mesh.
1.7 — Fan/Motor Cassette
The fan and motor assemblies are designed as a cassette so that they can be removed from the front of the boiler
without opening the front door. The front door davit arm can be used to remove the assembly (100-200 HP have
a hinged front door and a davit specifically for blower use). When removing the cassette use the lifting lugs provided (3-point rigging recommended for 350-1200 HP).
FIGURE 1-6. Fan/Motor Cassette
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CBEX Elite 100-1200 HP
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Basics
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CBEX Elite 100-1200 HP
CHAPTER 2 Burner and Fuel System
2.1 — The Burner
The oil burner is of the low pressure, air atomizing (nozzle) type. The gas burner is of the non-premix orifice type.
The burners are ignited by a spark ignited interrupted type gas pilot. The pilot is extinguished after the main
flame is established.
Burners equipped to burn oil and gas (combination burners) include equipment for each fuel. Since the burner
uses only one type of fuel at a time, a gas/oil selector switch is incorporated.
Regardless of which fuel is used, the burner operates with full modulation (within its rated operating range). The
burner returns to minimum firing position for ignition.
A flame detector is present to supervise both oil and gas flames, and to shut the burner down in the event of loss
of flame.
The control sequence provides a pre-purging period, proving of the pilot and main flame, and a period of continued blower operation to post-purge the boiler of all unburned fuel vapor. Other safety controls shut down the
burner under low-water conditions or excess steam pressure (water temperature).
Safety interlock controls include combustion and atomizing air proving switches and, depending upon the fuel
and insurance carrier requirements, controls that prove the presence of adequate fuel pressure.
The sequence of burner operation from startup through shutdown is governed by the Hawk controls in conjunction with the operating, limit, and interlock devices. The devices are wired into the circuitry to provide safe operation and protect against incorrect operating techniques.
All CBEX Elite boilers have the burner assembly integral with the front head. The entire head may be swung open
for inspection and maintenance.
Combustion air is provided by a centrifugal blower located in the front head. Combustion air delivery to the
burner is under the control of the damper actuator.
Filtered primary air for atomizing fuel oil is furnished independently of combustion air by an air pump.
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CBEX Elite 100-1200 HP
2-1
Burner and Fuel System
1
2
3
4
5
6
7
8
9
10
3
3
3
The burner control circuit operates on 115 volt, single-phase 60 Hz (or 50 Hz when equipped) alternating current. The forced draft fan motor is generally operated on 3-phase service at the available main power supply voltage.
2.2 — Front Head and Panel
Front head, control/entrance panel, and additional components associated with the combustion process are
described below. Boilers with optional features may have components not listed here.
FIGURE 2-1. CBEX Steam Boiler
Component Description
1. Forced Draft Fan Motor Drives forced draft fan directly to provide combustion air. Also referred to as a
blower motor.
2. Forced Draft Impeller Provides all air, under pressure, for combustion of pilot fuel and main fuel, and for
purging.
3. Actuators Independent actuators for fuel, air, and FGR operate to provide proper air/fuel
ratios under all boiler load conditions.
4. Ignition Transformer Provides high voltage spark for ignition of gas pilot or light oil pilot.
5. Flame Detector Monitors gas or oil pilot and energizes the programmer flame relay in response to
6. Stack Thermometer Indicates temperature of vented flue gases.
a flame signal. It continues to monitor main flame (oil or gas) after expiration of
pilot providing period. A standard equipped boiler has a lead sulfide (infrared sensitive) detector.
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CBEX Elite 100-1200 HP
2.3 — Gas System
1
2
3
4
Component Description
7. Control panel Houses the touchscreen HMI and boiler control system. Controller automatically
programs each starting, operating, and shutdown period in conjunction with operating limit and interlock devices. Includes, in a timed and proper sequence, the
operation of the blower motor, ignition system, fuel valve(s), damper, and FGR.
The sequence includes air purge periods prior to ignition and upon burner shutdown.
8. Entrance box Houses high voltage equipment including motor starters and fuses.
9. Gas train See 2.3
10. Oil system See 2.4
The flame detector portion of the control monitors both oil and gas flames and provides protection in the event of
loss of a flame signal.
The control recycles automatically during normal operation, or following a power interruption. It must be manually reset following a safety shutdown caused by a loss of flame. An internal checking circuit, effective on every
start, prevents burner operation in the event anything causes the flame relay to hold in during this period.
2.3 — Gas System
Depending upon the requirements of the insurance carrier or other governing agencies, the gas flow control system, or gas train, may consist of some, or all, of the following items. Refer to the Dimension Diagram (DD) prepared by Cleaver-Brooks for the installation.
Item numbers refer to the table following the illustrations.
FIGURE 2-2. Pilot Gas Train
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CBEX Elite 100-1200 HP
2-3
FIGURE 2-3. Main Gas Train
55
9
9
6
7
8
10
11
Burner and Fuel System
Component Description
1. Pilot Gas Shutoff Cock For manually opening or closing the pilot gas supply.
2. Pilot Gas Pressure Regulator Reduces incoming gas pressure to suit the pilot.
3. Pilot Gas Pressure Gauge Indicates gas pressure to pilot.
4. Pilot Gas Valve A solenoid valve that opens during the ignition period to admit fuel to the pilot. It
closes after main flame is established. The sequence of energizing and de-energizing is controlled by the programming relay. A second gas pilot valve may be
required by insurance regulations.
5. Gas Shutoff Cock The upstream gas cock manually opens and closes the main fuel gas supply. A
second shutoff cock, downstream of the main gas valve(s), is installed to provide
a means of shutting off the gas line whenever a test is made for leakage across the
main gas valve.
6. Low Gas Pressure Switch A pressure actuated switch that is closed whenever main gas line pressure is
above a preselected pressure. Should the pressure drop below the setting, the
switch contacts open a circuit causing the main gas valve(s) to close, or prevent
the burner from starting. The switch is usually equipped with a device that must
be manually reset after being tripped.
7. Main Gas Valves Electrically actuated shutoff valves that open simultaneously to admit gas to the
burner. The downstream valve is equipped with a “proof of closure” switch that is
connected into the pre-ignition interlock circuit.
8. Gas Valve Actuator w/o POC Dual-body gas valve includes regulating valve with POC (see below) and second
motorized safety shutoff valve.
9. Leakage Connection The body of the gas valve has a plugged opening that is used whenever it is necessary to conduct a test for possible leakage across the closed valve.
10. Gas Regulating Actuator w/
POC
Regulates gas pressure to the pressure range required by the burner. Includes
proof-of-closure switch.
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CBEX Elite 100-1200 HP
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2.4 — Oil System
Component Description
11. High Gas Pressure Switch A pressure actuated switch that is closed whenever main gas line pressure is
below a preselected pressure. Should the pressure rise above the setting, the
switch contacts will open a circuit causing the main gas valve(s) to close, or prevent the burner from starting. The switch is usually equipped with a device that
must be manually reset after being tripped.
12. Butterfly Gas Valve (not
shown)
The pivoted disc in the valve is actuated by connecting linkage from the gas modulating cam to regulate the rate of gas flow to the burner.
2.4 — Oil System
The following items are applicable to all oil fired or combination fired boilers.
Component Description
Oil Drawer Switch Opens the limit circuit if the oil drawer burner gun is not latched in the forward
position required for burning oil.
Atomizing Air Proving Switch Pressure actuated switch whose contacts are closed when sufficient atomizing air
pressure from the air pump is present for oil firing. Oil valve(s) will not open, or
will not remain open, unless switch contacts are closed.
Atomizing Air Pressure Gauge Indicates the atomizing air pressure at the burner gun.
Oil Solenoid Valves Opens when energized through contacts in the programmer and allows fuel oil to
flow from the oil metering valve to the burner nozzle. A light oil fired burner uses
two valves operating simultaneously.
Fuel Oil Controller An assembly combining into a single unit the gauges, regulators, and valves
required for regulating the flow of fuel oil. All controllers have the following integral parts.
A. Oil Metering Valve: Valve metering stem moves to increase or decrease the
orifice area to regulate the supply of fuel oil to the burner nozzle in accordance with boiler load variances. Stem movement is controlled by the oil
fuel actuator.
B. Oil Burner Pressure Gauge: Indicates pressure of the fuel oil at the metering
valve.
C. Oil Pressure Regulator: For adjustment of the pressure of oil at the metering
valve.
Oil Relief Valve Maintains a constant oil supply pressure to the fuel oil controller by bypassing
excess fuel oil.
Terminal Block Provides connections for fuel oil supply piping.
Fuel Oil Strainer Prevents foreign matter from entering the burner system.
Back Pressure Orifice A restriction located in the oil return line immediately downstream of the fuel oil
controller to create back pressure (100 and 200 series only).
Low Oil Pressure Switch
(optional)
Switch contacts open when the fuel oil pressure drops below selected pressure.
Switch will interrupt the limit circuit upon loss of sufficient fuel oil pressure for
correct combustion.
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CBEX Elite 100-1200 HP
2-5
Burner and Fuel System
Component Description
Fuel Oil Pump Transfers fuel oil from the storage tank and delivers it under pressure to the burner
system.
Air Pump Module Assembly Provides the compressed air required to atomize the fuel oil for proper combus-
tion. It is started automatically by the programmer’s sequence.
2.5 — Controls for Combination Burners Only
Gas-Oil Switch: Burners equipped to burn either oil or gas include equipment for each fuel. The selector switch
engages the appropriate interlocks and controls for gas or oil operation. Chapter 4 details the required functions
of each fuel system.
2.6 — Combustion Air
Air for combustion of fuel (referred to as “secondary” air) is furnished by the forced draft fan mounted in the
boiler head. In operation, air pressure is built up in the entire head and is forced through a diffuser plate for a
thorough mixture with the fuel for proper combustion. The supply of secondary air to the burner is governed by
automatically throttling the output of the fan by regulating the rotary air damper. The damper provides the proper
amount of air for correct ratio of air to fuel for efficient combustion at all firing rates.
The use of a Variable Speed Drive (VSD), optional, works in conjunction with the air damper actuator. When high
fire is not required the VSD reduces amperage to the fan motor, reducing energy consumption and the corresponding air flow simultaneously.
FIGURE 2-4. Secondary Air Flow Diagram
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CBEX Elite 100-1200 HP
2.7 — Automatic Ignition
2.7 — Automatic Ignition
Oil or gas burners are ignited by an interrupted type pilot. The pilot flame is ignited automatically by an electric
spark.
Burners are equipped with a gas burning pilot. In the case of a combination burner, the gas pilot is used to ignite
either the main gas flame or the oil flame.
At the beginning of the ignition cycle, and governed by the program relay and the Hawk control system, the pilot
solenoid valve and ignition transformer are simultaneously energized.
The ignition transformer supplies high voltage current for the igniting spark. A gas pilot has a single electrode and
a spark arcs between the tip of the electrode and the wall of the tube surrounding it. A light oil pilot has two electrodes and the arc is between their tips. The pilot solenoid valve and the transformer are de-energized after main
flame is ignited and established.
Fuel for the gas pilot is supplied from the utility’s main, or from a tank (bottle) supply. Secondary air flows into
and mixes with the pilot gas stream to provide an adequate fuel and air mixture for combustion.
Insurance regulations may require two gas pilot solenoid valves with a normally open vent valve between them.
The vent valve closes when the gas pilot valves open, and opens when the gas pilot valves shut to vent gas,
should any be present in the pilot line during the de-energized period of the gas pilot valves.
2.8 — Atomizing Air
Air for atomizing the fuel oil (referred to as “primary” air) is pumped by the air pump into the air-oil receiver tank
and delivered under pressure through a manifold block to the oil burner nozzle.
The atomizing air mixes with the fuel oil just prior to the oil leaving the nozzle.
Atomizing air pressure is indicated by the air pressure gauge on the burner gun.
Air pressure from the pump also forces sufficient oil from the tank to the pump bearings to lubricate them and
also to provide a seal and lubrication for the pump vanes. As a result, the air delivered to the tank contains some
lube oil; however, most of it is recovered through baffles and filters in the tank before the air passes to the burner.
Some of the primary air is also used to assist the oil pressure regulators of the fuel oil controller. Further explanation is given in Chapter 5.
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2.9 — Oil Fuel Flow
In Figure 2-9 the oil flow is indicated by arrows and the pertinent controls are identified.
Burner and Fuel System
FIGURE 2-5. Diagram for Light Oil Flow
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2.10 — Gas Fuel Flow
Fuel oil is delivered into the system by a supply pump which delivers part of its discharge to the oil burner.
Excess oil is returned to the oil storage tank through the fuel oil relief valve and oil return line. Normally, the
pump operates only while the burner is in operation, although a positioning switch is often provided so that either
continuous or automatic pump operation can be obtained.
The oil flows through a fuel oil strainer to prevent any foreign material from flowing through the control valves
and nozzle. The fuel oil controller contains in a single unit a metering valve, a regulator, and a gauge required to
regulate the pressure and flow of oil to the burner. The adjustable regulator controls the pressure. To assist in the
regulations, back pressure is created by an orifice nozzle located in the oil return line immediately downstream of
the fuel oil controller.
The programming relay energizes or de-energizes the solenoid oil valves to permit or cut off oil flow to the burner.
Two valves, operating simultaneously, are used. The valves are closed when de-energized. They cannot be
opened (energized) unless the combustion air proving switch and the atomizing air proving switch are closed.
The two switches are satisfied, respectively, by sufficient combustion air pressure from the forced draft fan and
pressurized air from the air pump.
The oil flow to the burner is controlled by the movement of the metering stem in the oil metering valve, which
varies the flow to meet load demands. The metering valve and the air damper are controlled simultaneously at all
times by independent actuators to proportion combustion air and fuel for changes in load demand.
2.10 — Gas Fuel Flow
Metered gas from the utility flows through the pressure regulator at a reduced pressure suitable to burner requirements, through the main gas shutoff cock, main gas valve(s), and modulating butterfly gas valve to the nonpremix orifice-type burner.
The main gas valve is of the normally closed type, and is opened (energized) in proper sequence by the programming relay.
The butterfly gas valve modulates the flow of gas from low through high fire settings. The position of the butterfly
valve disc is governed by the gas valve actuator. The butterfly gas valve and the air control damper are controlled
simultaneously by independent actuators to proportion combustion air and fuel for changes in load demand.
The gas flow rate required for rated burner input depends upon the heating valve (Btu/cubic foot) of the gas supplied. The gas pressure regulator adjusts the gas pressure (flow rate) to the entrance of the gas train. The regulator is not always supplied with the burner, but may be provided by others.
The main gas valves cannot be energized (opened) unless the combustion air proving switch is closed to indicate
a sufficient supply of combustion air. The low gas pressure and high gas pressure switches must be closed to
prove sufficient, but not excessive, gas fuel pressure.
2.11 — Modulating Firing
A combustion curve for each fuel is programmed into the Hawk controls during boiler commissioning. The combustion curve settings will determine how the butterfly gas valve (or the oil metering valve), air damper, and FGR
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Burner and Fuel System
damper are positioned throughout the boiler’s firing range. When properly adjusted, the combustion settings will
maintain the correct air/fuel ratio while responding to changing load conditions.
During burner operation, the process variable (steam pressure or water temperature) is compared to the setpoint
to determine the control signal sent to the actuators.
Manual burner operation is possible through the Hawk control system. Manual mode is used primarily for initial
setting or subsequent checking of fuel input. Normal operation should be with the manual-automatic selector in
the “automatic” position.
A feature designed into the control program maintains the boiler in the low-fire position during ignition and keeps
it there until the main flame is established.
2.12 — Ultra Low NOx Systems
For Ultra low NOx (<15 PPM) operation refer to the NTI burner manual 750-220.
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CHAPTER 3 Waterside Care
3.1 — Overview
The operator should be familiar with this chapter before attempting to place the unit into operation.
Although it is of prime importance, the subject of water supply and treatment cannot adequately be covered in
this manual. For specific information or assistance with your water treatment requirements, contact your CleaverBrooks service and parts representative.
Feedwater equipment should be checked and ready for use. Be sure that all valves, piping, boiler feed pumps,
and receivers are installed in accordance with prevailing codes and practices.
Water requirements for both steam and hot water boilers are essential to boiler life and length of service. It is
vital care be taken in placing the pressure vessel into initial service. The waterside of new boilers and new or
remodeled steam or hot water systems may contain oil, grease or other foreign matter. A method of boiling out
the vessel to remove the accumulations is described later in this chapter.
Boilers require proper water circulation. The system must be operated as intended by its designer in order to
avoid thermal shock or severe, possibly damaging, stresses from occurring to the pressure vessel.
NOTE: For purposes of this manual, ‘hot water boiler’ covers boilers using water. Glycol solutions have different
operating requirements, circulation rates, temperatures, etc.
3.2 — Water Requirements
3.2.1 — Hot Water Boilers (100-800 HP only)
Air Removal
The hot water outlet includes a dip tube which extends 2 to 3 inches into the boiler. Oxygen or air released in the
boiler will collect or be trapped at the top of the boiler shell. The dip tube reduces the possibility of air, which
may be trapped at the top of the shell, from entering into the system.
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Waterside Care
FIGURE 3-1. Dip Tube
The air vent tapping on the top center line of the boiler should be piped into the expansion or compression tank.
Air trapped at the top of the boiler will find its way out of the boiler through the tapping.
Minimum Water Temperature
The minimum recommended boiler water temperature is 170º F. When water temperatures lower than 170º F
are used, the combustion gases are reduced in temperature to a point where water vapor condenses, which can
cause corrosion in the boiler and stack.
Condensation is more severe on a unit that operates intermittently and which is greatly oversized for the actual
load. Condensation can be minimized by maintaining boiler water temperatures above 170º F.
Rapid Replacement of Boiler Water
The system layout and controls should be arranged to prevent the possibility of pumping large quantities of cold
water into a hot boiler, which will cause shock or thermal stresses. Water temperature in a boiler of 200° F or
240° F cannot be completely replaced with 80° F water in a few minutes time without causing thermal stress.
The same fact applies to periods of normal operation, as well as during initial startup.
When individual zone circulating pumps are used, it is recommended that they be kept running-even though the
heat users do not require hot water. The relief device or bypass valve will thus allow continuous circulation
through the boiler and can help prevent rapid replacement of boiler water with cold zone water.
Continuous Flow Through the Boiler
The system should be piped and the controls arranged to allow water circulation through the boiler under all
operating conditions. The operation of three-way valves and system controls should be checked to be sure that
the boiler will not be by-passed. Constant circulation through the boiler mitigates the possibility of stratification
within the boiler and results in more even water temperatures to the system.
A rule of thumb of 3/4 to 1 gpm per boiler horsepower can be used to determine the minimum continuous flow
rate through the boiler under all operating conditions. The operator should determine that water flow exists
through the boiler before initial firing or refiring after boiler has been drained.
NOTE: If the operating water temperature going to the system must be lower than 170º F, the operating boiler water
temperature should be a minimum of 170º F and mixing valves should be used to avoid damage to the equipment.
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3.2 — Water Requirements
BHP
Boiler Output
MBTU/hr
System Temperature Drop - Degrees F
10 20 30 40 50 60 70 80 90 100
Maximum Circulating Rate - GPM
100 3,350 670 335 223 168 134 112 96 84 75 67
125 4,185 836 418 279 209 168 140 120 105 93 84
150 5,025 1,005 503 335 251 201 168 144 126 112 100
200 6,695 1,340 670 447 335 268 224 192 168 149 134
250 8,370 1.675 838 558 419 335 280 240 210 186 167
300 10,045 2,010 1,005 670 503 402 335 287 251 223 201
350 11,720 2,350 1,175 784 587 470 392 336 294 261 235
400 13,400 2,680 1,340 895 670 535 447 383 335 298 268
500 16,740 3,350 1,675 1,120 838 670 558 479 419 372 335
600 20,080 4,020 2,010 1,340 1,005 805 670 575 502 448 402
700 23,430 4,690 2,345 1.565 1,175 940 785 670 585 520 470
800 26,780 5,360 2,680 1,785 1,340 1,075 895 765 670 595 535
NOTE: The circulating pumps should be interlocked with the burner so that the burner cannot operate unless the cir-
culating pump is running in order to avoid damage to the equipment.
Wat er Circulation
The Maximum Circulating Rate Chart, Figure 3-2, shows the maximum gpm circulation rate of boiler water in
relation to full boiler output and system temperature drop.
FIGURE 3-2. Maximum Circulating Rate Chart
Multiple Boiler Installations
When multiple boilers are used, care must be taken to ensure adequate or proportional flow through the boilers.
Proportional flow can best be accomplished by use of balancing valves and gauges in the supply line from each
boiler. If balancing valves or orifice plates are used, a significant pressure drop (e.g., 3-5 psi) must be taken
across the balancing device to accomplish the purpose.
If care is not taken to ensure adequate or proportional flow through the boilers, wide variations in firing rates
between the boilers can result.
In extreme cases, one boiler may be in the high-fire position while the other boiler or boilers may be at low fire.
The net result would be that the common header water temperature to the system would not be up to the desired
point.
Pump Location
It is recommended that the system circulating pumps take suction from the outlet connection on the boiler, and
that they discharge to the system load. The suction side is preferred because it decreases air entry into the system and does not impose the system head on the boiler.
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Waterside Care
Pump Operation
Pumps are normally started and stopped by manual switches. It is also desirable to interlock the pump with the
burner so that the burner cannot operate unless the circulating pump is running.
Pressure
The design of the system and usage requirements often dictate the pressure exerted upon the boiler. Some systems are pressurized with air, or with an inert gas such as nitrogen. Caution must be exercised to ensure that the
proper relationship of pressure-to-temperature exists within the boiler so that all of the boiler’s internal surfaces
are fully wetted at all times. For this reason, the internal boiler pressure, as indicated on the water pressure
gauge, must be held to the level shown in the Internal Boiler Pressure graph below.
FIGURE 3-3. Internal Boiler Pressure
When initially firing a newly installed boiler, or when cutting an existing boiler into an operating system, the
boiler or boilers to be cut into operation MUST be pressurized equal to the system and/or other boilers prior to
opening the header valves.
It is advisable to have a thermometer installed in the return line to indicate return water temperature. Knowing
the supply water temperature, the boiler system differential can be established. With knowledge of the pumping
rate, the operator can easily detect any excessive load condition and take appropriate corrective action.
Special caution must be taken to guard against any condition, or combination of conditions, that might lead to
the transfer of cold water to a hot boiler or hot water to a cold boiler. It cannot be over-emphasized that rapid
changes in temperature within the boiler can, and sometimes do, cause damage.
3.2.2 — Steam Boilers
Feed Pump Operation
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CBEX Elite 100-1200 HP
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3.3 — Water Treatment
!
Warning
2
1
3
3
4
5
6
Globe Valve
Check Valve
ITEM
2
1
DESCRIPTION
Globe Valve
Gate Valve
3
4
Feedwater Valve 5
Strainer 6
Before turning on the pump motor be certain that all valves in the water feed line are open to prevent possible
damage to the feed pump mechanism. After opening the valves, momentarily energize the feed pump motor to
establish correct pump rotation. With the correct rotation established, close the boiler feed pump entrance
switch. The pump should shut down when the water level reaches the proper level.
Feedwater pumps must have adequate capacity to maintain required water level under all operating conditions.
Check the feedwater pumps periodically and maintain as necessary to prevent unexpected breakdowns.
NOTE: Prior to operating the pump, carefully check the alignment of the flexible coupling, if one is used. A properly
aligned coupling will last a long time and provide trouble-free mechanical operation.
NOTE: In the event that water column isolation valves are provided, it must be established that the valves are open
and sealed or locked in the open position. If the valves are installed, it is illegal to operate the boiler with closed or
unsealed open valves.
The isolation valves and the water column piping must be locked open during operation. Failure to do so may result
in a low water condition. Failure to follow these instructions could result in serious injury or death.
FIGURE 3-4. Feed piping, typical
3.3 — Water Treatment
Properly treated boiler feed water, coupled with good engineering and operating practices, lead to maximum
effectiveness and long trouble-free life of pressure vessels. Contact your local Cleaver-Brooks authorized representative for information on how to prevent the presence of unwanted solids and corrosive gases.
Objectives of water treatment are:
1. Prevent hard scale deposits or soft sludge deposits, which reduce heat transfer and can lead to overheated
metal and costly downtime and repairs.
2. Eliminate corrosive gases in the supply or boiler water.
3. Prevent inter-crystalline cracking or caustic embrittlement of boiler metal.
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Waterside Care
4. Prevent carryover and foaming.
Accomplishment of the above objectives generally requires proper feedwater treatment before and after introduction of the water into the boiler. The selection of pre-treatment processes depends upon the water source, its
chemical characteristics, amount of makeup water needed, plant operating practices, etc. Treating methods
include filtering, softening, de-mineralizing, deaerating, and preheating. After-treatment involves chemical treatment of the boiler water.
Because of the variables involved, no single boiler compound can be considered a “cure-all” nor is it advisable to
experiment with homemade treating methods. Sound recommendations and their employment should be augmented by a periodic analysis of the feedwater, boiler water, and condensate.
The internal or waterside surfaces of the pressure vessel should be inspected with enough frequency to determine the presence of any contamination, accumulations of foreign matter, or corrosion, and/or pitting. If any of
the conditions are detected, contact your local Cleaver-Brooks authorized representative for advice on corrective
action.
A properly sized water meter should be installed in the raw water make-up line in order to accurately determine
the amount of raw water admitted to the boiler (steam or hot water) and to aid in maintaining proper waterside
conditions.
3.4 — Cleaning
3.4.1 — Hot Water and Steam Piping
Steam and water piping systems connected to the boiler may contain oil, grease, or foreign matter. The impurities must be removed in order to prevent damage to pressure vessel heating surfaces. On a steam system, the
condensate should be wasted until tests show the elimination of undesirable impurities. During the period that
condensate is wasted, attention must be given to the treatment of the raw water used as make-up so that an
accumulation of unwanted materials or corrosion does not occur. For more information, contact your local
Cleaver- Brooks authorized representative.
On a hot water system, chemical cleaning is generally necessary and the entire system should be drained after
treatment. Consult your local Cleaver-Brooks authorized representative for recommendations, cleaning compounds, and application procedures.
3.4.2 — Pressure Vessel
The waterside of the pressure vessel must be kept clean from grease, sludge, and foreign material. Such deposits, if present, will shorten the life of the pressure vessel, will interfere with efficient operation and functioning of
control and safety devices, and quite possibly cause unnecessary and expensive rework, repairs, and downtime.
The installation and operating conditions that the boiler will be subjected to should be considered and cleaning
of the waterside of the pressure vessel should be provided during the course of initial start-up.
The pressure vessel and the steam and return lines or hot water piping represent, in effect, a closed system.
Although the steam and return (condensate) lines or the hot water piping system may have been previously
cleaned, it is possible that:
1. Cleaning has been inadequate.
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