Facts worth knowing about Oil nozzles - Danfoss.com

Can the nozzle cause too low a flue-gas temperature?When the flue-gas temperature is too low, for example 170-180°C, it isusually a sign of good operating economy. However, since there is a dangerthat water vapour in the gas (1 litre water vapour per kg oil) will condenseand cause damage inside the chimney and draught pipe, te reason for the lowtemperature ought to be established. The following causes should beinvestigated:• Too small an oil nozzle has been chosen in relation to boiler capacity. Seesection “How is the correct oil nozzle chosen?”• Too low an oil pressure. Although this will most often give rise to poorcombustion with soot formation.• Perhaps the boiber baffle plates are too effective for the plant. This canreveal that the relation between nozzle size and boiler capacity isincorrect.• Cold air entry into the flue pipe cools the gas down so that its temperatureappears to be low. This condition can be checked by taking CO 2 %measurements in the pipe. If the CO 2 % is low, 4-5% for example, whilethat measured in the combustion chamber is up on 10-12%, it is a suresign of air penetration through the boiler casing or through the jointbetween boiler casing and flue pipe.Note!A lower flue-gas temperature to gain better operating economy is moredefensible on a plant with a well-lined chimney than on one with a poorchimney lining (and, without doubt, internal chimney dimensions which arealtogether too large).33