Fuel / Air Ratio Control System; Burner Control Section - Siemens LMV51 Series Basic Documentation

Fuel / air ratio control
system

Burner control section

Siemens Building Technologies
HVAC Products
The following parameters are of particular importance:
The setting values (curve parameters) for the actuating devices, the types of fuel and
the combustion air across the burner's load range must be stored in adequate num-
bers.
While considering the combustion chamber pressure, fuel pressure as well as tempera-
ture and pressure of the combustion air, assignment of the selected setting values of
fuel and combustion air must be made such that correct operation with sufficient
amounts of excess air is ensured across the entire burner load range.
Proof of this must be delivered by the burner / boiler manufacturer by measuring the
combustion characteristics. When using a VSD, the fan will be run to the steady-state
condition. Hence, the burner's nominal load refers to the fan speed acquired with speed
standardization.
Fuel train parameterization (G, Gp1, Gp2, LO, HO, LOgp, HOgp, refer to chapter 3 Fuel
train applications (examples) must be checked prior to commissioning to ensure it
agrees with the fuel trains implemented on the burner and to make certain the valves
are correctly assigned to the valve outputs on the LMV5... .
The correct setting of the time parameters, especially the safety and prepurge times
(separately for oil and gas), must be checked.
It must also be checked if, in the case of plants with continuous operation, flame detec-
tor type QRI... (or the ionization probe) is used, because only these are suited for con-
tinuous operation.
Further, the function of the flame detector in the event of loss of flame during operation
and with extraneous light during the prepurge time, or in the case there is no establish-
ment of flame at the end of the safety time, must be checked.
(With the QRI... flame detector, generation of an extraneous light signal is achieved by
simulating a flickering flame with an artificial light source).
The functions of all available or required input messages must be checked, for exam-
ple:
• Air pressure
• Minimum gas pressure
• Maximum gas pressure
• Gas valve proving or CPI
• Minimum oil pressure
• Maximum oil pressure
• Safety loop (e.g. SLT)
• Fan contactor contact in at least 2 phases (e.g. prepurge and operation)
It is to be checked whether gas valve proving is activated if required by the application.
If yes, the correct leakage rate is to be checked. For details, refer to chapter «Gas
valve proving».
In the case of dual-fuel burners, short preignition_Oil (from Phase 38) must be param-
eterized when firing on oil, and the oil pump must be equipped with a magnetic clutch,
for example, ensuring that the oil pressure will be increased in Phase 38 before ignition
takes place. In addition, parameter «OilPumpCoupling» must be set to «Magnetcoupl».
Pure oil burners do not require a magnetic clutch, in which case long preignition_Oil
(from Phase 22) is to be parameterized, or parameter «OilPumpCoupling» is to be set
to «Directcoupl».
Basic Documentation LMV5...
13 Duties of the authorized inspector
199/301
CC1P7550en
13.08.2004