Unigas HTP2000 Installation Manual page 26

PART III: OPERATION
Light oil operation
The fan motor starts and the pre-purge phase as well. Since the pre-purge phase must be carried out at the maximum air rate, the
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control box drives the actuator opening and when the maximum opening position is reached, the pre-purge time counting starts.
At the end of the pre-purge time, the actuator is in the light oil ignition position: the ignition transformer is energised (lamp B4 on);
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the ignitor gas valves (if provided) and the light oil valves open. Few seconds after the valves opening, the transformer is de-ener-
gised and lamp B4 turns off.
The burner is now operating, meanwhile the actuator goes to the high flame position; after some seconds, the two-stage operation
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begins; the burner is driven automatically to high flame or low flame, according to the plant requirements.Operation in high or low
flame is signalled by LED B2 on the burner control panel.
AIR FLOW AND FUEL ADJUSTMENT
WARNING! During commissioning operations, do not let the burner operate with insufficient air flow (danger of
formation of carbon monoxide); if this should happen, make the fuel decrease slowly until the normal combustion
values are achieved.
WARNING! the combustion air excess must be adjusted according to the values in the following chart.
Adjustments - brief description
The air and fuel rates adjustments must be performed at the maximum ouptput first ("high flame"): see the LMV5.. related manual..
Check that the combustion parameters are in the suggested limits.
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Check the flow rate measuring it on the counter or, if it was not possible, verifying the combustion head pressure by means of a dif-
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ferential pressure gauge, as described on par. "Measuring the gas pressure in the combustion head".
Then, adjust the combustion values by setting the "gas/air" ratio" curvepoints (see the LMV5.. related manual).
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Set, now, the low flame output, in order to avoid the low flame output increasing too much or that the flues temperature gets too low
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to cause condensation in the chimney.
Adjusting procedure
Go on adjusting the burner.
Users can set only the LMV parameters that can be accessed without password: (see "Adjusting the temperature set-point").
The Siemens AZL User Interface allows programming the Siemens LMV system and monitoring the system data.
The user interface is made of:
1. display: it showes menus and parameters
2. ESC key (previous level): it goes back to the prevoius level menu or exits the programming mode without changing data.
3. ENTER key (next level): it confirms the data changing and jumps to the next menu/parameter.
4. SELECT keys: they select a menu item and change the parameter values.
As far as the settings, see the LMV5 related manual.
By following the "air/gas ratio" curvepoints setting procedure on the LMV5.. manual, adjusting the air and gas flow rates: check, conti-
nuosly, the flue gas analisys, as to avoid combustion with little air; dose the air according to the gas flow rate change following the steps
quoted below.
Recommended combustion parameters
Recommended (%) CO
Fuel
Natural gas
Light oil
1
2
/
Recommended (%) O
2
9 ÷ 10
11.5 ÷ 13
4
3
26
2
3 ÷ 4.8
2.9 ÷ 4.9