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Eclipse ThermJet Self-Recuperative, V5, Design Guide 208, 9/16/2011
Step 3: Ignition System
Ignition Transformer
For the ignition system, use a transformer with:
• 6000 VAC transformer
• full-wave spark
• one transformer per burner
DO NOT USE
the following:
• 10000 VAC transformer
• twin outlet transformer
• distributor type transformer
• half-wave transformer
Eclipse recommends a low fire start be used. However,
ThermJet Self-Recuperative burners are capable of direct
spark ignition anywhere within the operating range. See
the Installation Guide for detailed start information.
NOTE:
You must follow the control circuits described in
the previous section, “Control Methodology”, to obtain
reliable ignition.
Local safety and insurance require limits on the maximum
trail for ignition time. These time limits vary from country
to country.
The time it takes for a burner to ignite depends on:
• the distance between the gas shut-off valve and the
burner
• the air/gas ratio
• the gas flow at start conditions
It is possible to have the low fire too low to ignite within the
trail for ignition period. Under these circumstances you
must consider the following options:
• start at higher input levels
• resize and/or relocate the gas controls
• use bypass start gas
Step 4: Flame Monitoring Control System
The flame monitoring control system consists of two main
components:
• flame sensor
• flame monitoring control
Flame Sensor
UV Scanners can be used on ThermJet Self-Recuperative
burners.
The UV scanner must be compatible to the flame
monitoring control that is used. Refer to the manual of
your selected control for proper selection of the scanner.
Flame Monitoring Control
The flame monitoring control processes the signal from
the flame sensor and controls the start-up and shut-down
sequences.
Eclipse recommends the following flame monitoring
controls:
• Trilogy series T400 (Instruction Manual 830)
• Veri-Flame series 5600 (Instruction Manual 818)
• Bi-Flame series 6500 (Instruction Manual 826)
• Multi-Flame series 6000 (Instruction Manual 820)
If other controls are considered, contact Eclipse to
determine how burner performance may be affected.
Flame monitoring controls that have lower sensitivity
flame detecting circuits may limit burner turndown and
change the requirements for ignition.
Flame monitoring controls that stop the spark as soon as
a signal is detected may prevent establishment of flame,
particularly when using UV scanners. The flame
monitoring control must maintain the spark for a fixed time
interval that is long enough for ignition.
Step 5: Combustion Air System
Blower Motor Type
Effects of Atmospheric Conditions
The blower data is based on the International Standard
Atmosphere (ISA) at Mean Sea Level (MSL), which
means that it is valid for:
• sea level
• 29.92" Hg (1013 mbar)
• 70°F (21°C)
The makeup of the air is different above sea level or in a
hot environment. The density of the air decreases, and as
a result, the outlet pressure and the flow of the blower
decrease. An accurate description of these effects is in the
Eclipse Combustion Engineering Guide (EFE 825). The
guide contains tables to calculate the effect of pressure,
altitude and temperature on air.
Blower
The rating of the blower must match the system
requirements. You can find all the blower data in Bulletin/
Info Guide 610.
1. Calculate the Outlet Pressure
When calculating the required outlet pressure of the
blower, the total of these pressures must be calculated.
• the static air pressure required at the burner
• the total pressure drop in the piping
• the total of the pressure drops across the valves
• a minimum safety margin of 10%