CleaverBrooks CBEX Elite, Эксплуатация и обслуживание

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Adjustment Procedures
6-2 750-368
CBEX Elite 100-1200 HP
1.
Operating Limit Control : Senses pressure or temperature and automatically turns the burner on to initiate the
startup sequence when required and turns the burner off to initiate the shutdown sequence when the demand
is satisfied. The control must be set to initiate startup only at the low-fire position.
2.
High Limit Control : Senses the steam pressure or hot water temperature. It is used as a safety limit to turn
the burner off in the event the operating limit control fails. The high limit control should be set sufficiently
above the operating limit control to avoid nuisance shutdowns, because it has a manual reset feature
When adjusting or setting controls, first be sure all control devices are securely mounted and level. With the tem-
perature sensing control, make sure the sensing bulb is properly bottomed in its well and is secured against
movement. Be sure the connecting tubing is not kinked.
The dial settings are generally accurate, although it is not unusual to have a slight variation between a scale set-
ting and an actual pressure gauge or thermometer reading. Always adjust control settings to agree with pressure
gauge or thermometer readings. Accurate instrument readings are required. When necessary use auxiliary test
equipment to set controls.
Burner controls correctly set to match load demands will provide operational advantages and achieve the follow-
ing desirable objectives:
•
The burner will be operating in low-fire position prior to shutdown.
•
The burner will operate at low-fire for a brief period on each start during normal operation.
•
Eliminates frequent burner on-off cycling.
The Hawk system modulates the boiler firing rate according to stored combustion curves. The Firing Graph (Fig-
ure 6-1) depicts a typical setting relationship of the operating limit control, modulating control, and the high limit
control.
The burner will be “on” whenever the pressure or temperature is less than point B and “off” whenever pressure
or temperature is greater than point A . The distance between points A and B represents the “on-off” differential
of the operating limit control.
NOTE: Adjustments to the boiler operating controls should be made by an authorized Cleaver-Brooks Service Techni-
cian. Refer to the appropriate boiler Operation and Maintenance manual for specific information on boiler startup and
operation.