Oil Burners
Usually the oil burners are required to be used for small capacity boilers for industrial use. The purpose of an oil burner is to receive supply of oil, meter it according to the load on the plant, atomise and vapourise the oil completely. The mixing of oil with air is so provided that the oil could be burnt with minimum excess air for achieving the maximum temperatures.
Classification of Oil Burners :
1. Vapourising burners :
These are used for domestic and industrial applications c.g. in blow torches, gasoline stoves etc. These burners are not used for steam generation in boilers since the oil used is heavy.
2. Atomising burners :
The purpose of these burners is to atomise the fuel into fine particles and mix with air. These burners are used for oil fired furnaces and in case of furnaces for boilers. The atomisation of fuel can be accomplished by following methods :
(a) High pressure air or steam atomising burners :
- In this oil is forced through an orifice under a steam or air pressure. It is called blast atomisation.
- Its principle of working is shown in Figure A. This method of atomisation of oil is simple and cheap.
- The high velocity of steam or air divides the oil into very fine particles which are sprayed into the furnace.
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| Figure A |
(b) Mechanical burners :
- In these burners the atomisation of oil is not due to the fluid injected under pressure.
- These are further classified into spray nozzle burners and rotary burners.
- In case of spray nozzle burners the oil is injected under high pressure of about 20 to 30 bar pressure and at a temperature of 40° C to 150° C through small nozzles.
- The oil leaves the nozzles in atomised form.
- In case of rotary burners, the oil is passed under pressure into conical chamber with an orifice at its apex and due to centrifugal action the oil leaves the orifice in the form of a hollow cone of fine particles. Its principle of working is shown in Figure B.
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| Figure B |