dunphy TD - Oil Operating System Air; Steam Atomising

Operating Instructions For TD/TAD4 Dual Fuel Burner
June 13 50 of 165 TD/TAD4 Manual Rev 4
4.3.7 Oil Operating System Air / Steam Atomising
The ‘TA’ principle of operation is that oil, carrying both heat and hydraulic energy, enters a mixing
chamber in the nozzle where it is mixed with the streams of the atomising fluid (compressed air or
steam), carrying kinetic energy and in the case of steam, heat energy.
The combination of forces resulting from the directional differences between the oil flow, steam
flow and the kinetic and heat energy forces cause an emulsification process to take place.
The oil/steam or oil/air mixture then impinges on the nozzle pintle plate which gives secondary
atomisation, and finally passes out of the nozzle orifice which imparts a swirling motion into the
finely atomised spray. The emerging angle of the spray can vary according to the type of nozzle
fitted.
The oil supply from the pump passes through the pump discharge valve, the pre-heater the metering
valve and the nozzle line and goes back to the pump return via the V1 main oil valve and a non-
return valve. When the burner is switched on, the oil pre-heater (When fitted) is energised and the
oil temperature is raised to the required level. When the oil reaches the required temperature the
burner motor/pump is started and the oil is allowed to circulate through the burner pipework until
the correct temperature is attained throughout the system.
The check stat then sends a signal to the control box which starts the firing cycle by opening the air
damper to the high fire position. When the control box reaches the firing stage, the air damper
drives to low fire position and the ignition spark is switched on.
Both V1 normally open and V1N normally closed nozzle line solenoids are energised together
releasing oil through the nozzle, and the atomising medium solenoid (PV) opens to allow air or
steam into the nozzle mixing chamber.
The resulting mixture is ignited by the spark from the ignition electrode or by a pilot gas ignition
system.
The main oil pressure is set, by means of the pump pressure regulating screw and the atomising oil
pressure adjusted at the metering valve to give the correct low and high fire oil throughputs. The
atomising medium pressure must be adjusted at the pressure regulator (RG) in conjunction with the
oil pressure to ensure smooth light up and optimum combustion throughout the firing range.
The air shutter is adjusted to give optimum combustion efficiency throughout the firing range.