Abstract: An incinerator (20) for disposing of boil-off gas on an LNG carrier comprises a combustion section (40) wherein the boil-off gas admitted at (42) is burned in the presence of combustion air admitted at (44), producing a flame (46) and combustion products (C). Dilution air (A) is delivered into the combustion section (40) and mixed with the combustion products (C) to produce a diluted mixture (M). The combustion section (40) has an inner wall (48) and an outer wall (50) together defining a first passage (52) through which the dilution air (A) is passed before being mixed with the combustion products (C), whereby the dilution air A cools the combustion section (40). The dilution air A in the first passage (52) also provides a thermally insulting layer limiting radial heat transmission from the combustion section (40). A proportion (AP) of the dilution air is mixed directly with the combustion products (C).

Abstract: A flare stack comprises an upwardly extending gas discharge duct 10 and a pilot burner 16 operative at an burner location near the open top end of the duct 10 to ignite gas discharged by way of the duct. Atmospheric samples from the burner location are delivered to a monitoring station 20 remote from the duct 10 and at ground level 12. A sensor at the monitoring station 20 is responsive to a parameter of the sample indicative of combustion at the burner location such as increased CO2 or NOx or decreased O2. An igniter is operatively associated with the sensor and arranged to light the pilot burner 16 automatically if the sensor does not detect said parameter in the sample.