Flame spraying head with chamber and cooled spray tube

摘要

Main (4,5) and ancillary fuel (6) infeeds combine in a vaporising flame for the main fuel components, possibly using several ancillary feeds round the main feed plus a secondary combustion chamber (12) downstream of the main chamber (2) followed by an expansion nozzle (3a). The wall of both chambers and that of the nozzle are provided with cooling (11). Powder is fed in via ports (10) set downstream of the main combustion chamber, preferably sited in the secondary chamber ahead of the nozzle. The casing cooling gas enters via feeds (8,13). The area ratio of the main chamber (D1) to that (D2) of the secondary chamber ranges between 1:10 and 1:2 as compared with the ratio between main chamber diameter (D1) and the maximum diameter (D3) of the secondary combustion chamber which varies between 1:16 and 1:2.5. The energy of the main flame is provided by a mixture of fuel oil and oxygen, using the main flame to heat the fuel oil in the nozzle, and the vaporising flame to preheat the oil and oxygen mixture.