2.5.10
Draft Controller
a.
Draft controller shall match other controllers in system and shall
have capability of PI control of furnace draft in response to
changing furnace pressure and feed forward signal of boiler load.
b.
flame safeguard system so as to insure that prepurge, postpurge,
lightoff and burner modulate cycles are handled correctly and in
accordance with local regulations.
c.
Controller shall have characterizable setpoint curves for feed
forward signal based on load.
d.
respective engineering units:
1.
Controller output.
2.
Furnace draft.
3.
Furnace draft setpoint.
e.
Controller inputs shall be:
1.
Jackshaft output (Analog)
2.
Furnace draft (Analog).
3.
Purge from flame safeguard system (Contact).
4.
Auto from flame safeguard system (Contact).
5.
Remote alarm silence (Contact).
f.
Controller outputs shall be:
1.
Flue gas damper actuator (Analog).
2.
Remote audible alarm (Contact).
g.
Controller shall be provided with protocol converter/gateways with
controller LAN network interconnection to field panel controllers
[and to supervisory computer workstation.].
2.5.11
Oxygen Trim Controller
a.
Oxygen trim controllers shall match other controllers in the
system and shall have the capability of PID control of fuel/air
ratio in response to flue gas oxygen content.
b.
Controller shall be capable of calculating and displaying boiler
efficiency using ASME "By Losses" method.
c.
flame safeguard system so as to ensure the prepurge, postpurge,
lightoff and burner modulation cycles are handled correctly and in
accordance with local regulations.
SECTION 15561A
Page 48